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1.
  • Abadpour, Shadab, et al. (författare)
  • Interleukin-22 reverses human islet dysfunction and apoptosis triggered by hyperglycemia and LIGHT
  • 2018
  • Ingår i: Journal of Molecular Endocrinology. - 0952-5041 .- 1479-6813. ; 60:3, s. 171-183
  • Tidskriftsartikel (refereegranskat)abstract
    • Interleukin (IL)-22 has recently been suggested as an anti-inflammatory cytokine that could protect the islet cells from inflammation- and glucose-induced toxicity. We have previously shown that the tumor necrosis factor family member, LIGHT can impair human islet function at least partly via pro-apoptotic effects. Herein, we aimed to investigate the protective role of IL-22 on human islets exposed to the combination of hyperglycemia and LIGHT. First, we found up-regulation of LIGHT receptors (LTβR and HVEM) in engrafted human islets exposed to hyperglycemia (>11 mM) for 17 days post transplantation by using a double islet transplantation mouse model as well as in human islets cultured with high glucose (HG) (20mM glucose) + LIGHT in vitro and this latter effect was attenuated by IL-22. The effect of HG + LIGHT impairing glucose stimulated insulin secretion was reversed by IL-22. The harmful effect of HG + LIGHT on human islet function seemed to involve enhanced endoplasmic reticulum stress evidenced by up-regulation of p-IRE1α and BiP, elevated secretion of pro-inflammatory cytokines (IL-6, IL-8, IP-10 and MCP-1) and the pro-coagulant mediator tissue factor (TF) release and apoptosis in human islets, whereas all these effects were at least partly reversed by IL-22. Our findings suggest that IL-22 could counteract the harmful effects of LIGHT/hyperglycemia on human islet cells and potentially support the strong protective effect of IL-22 on impaired islet function and survival.
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2.
  • Alheim, Katarina, et al. (författare)
  • Identification of a functional glucocorticoid response element in the promoter of the cylcin-dependant kinase inhibitor p57(Kip2)
  • 2003
  • Ingår i: Journal of Molecular Endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 30:3, s. 359-368
  • Tidskriftsartikel (refereegranskat)abstract
    • Glucocorticoids are known regulators of the cell cycle, normally exerting an anti-proliferative effect. We have previously shown that glucocorticoids stimulate expression of p57(Kip2), a member of the Cip/Kip family of cyclin-dependent kinase inhibitors which, in some cell types, may account for the anti-proliferative responses seen after glucocorticoid treatment. The induction of p57(Kip2) involves primary transcriptional effects where no de novo protein synthesis is necessary, suggesting a direct interaction of the glucocorticoid receptor with the p57(Kip2) gene. In this study we have identified a functional glucocorticoid response element (GRE), located 5 kilo bases (kb) upstream of the transcription start site in the human P57(Kip2) promoter. This GRE was functional also when isolated, suggesting a direct transcriptional effect of the glucocorticoid receptor. Furthermore, mutation of this GRE abolished glucocorticoid induction of the reporter gene, whereas mutation of a nearby Sp1 site did not. Using electrophoretic mobility shift assays, we have shown that the -5 kb p57(Kip2) promoter GRE was able to compete with a well-known GRE for glucocorticoid receptor binding. Sequence comparisons with the mouse genome showed that this GRE is highly conserved, further strengthening the biological importance of this site. All these data emphasize the involvement of this GRE in the glucocorticoid-mediated induction of p57(Kip2) expression.
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3.
  • Baryshev, M, et al. (författare)
  • Unfolded protein response is involved in the pathology of human congenital hypothyroid goiter and rat non-goitrous congenital hypothyroidism
  • 2004
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 32:3, s. 903-920
  • Tidskriftsartikel (refereegranskat)abstract
    • The unfolded protein response (UPR) is an intracellular signaling pathway that regulates the protein folding and processing capacity of the endoplasmic reticulum (ER). The UPR is induced by the pharmacological agents that perturb ER functions but is also activated upon excessive accumulation of the mutant secretory proteins that are unable to attain correct three-dimensional structure and are thus retained in the ER. Such defects in intracellular protein transport underlie the development of a number of phenotypically diverse inherited pathologies, termed endoplasmic reticulum storage diseases (ERSD). We have studied UPR development in two similar ERSDs, human congenital goiter caused by the C1264R and C1996S mutations in the thyroglobulin (Tg) gene and non-goitrous congenital hypothyroidism in rdw dwarf rats determined by the G2320R Tg mutation. In both cases, these mutations rendered Tg incapable of leaving the ER. A major ER chaperone immunoglobulin-binding protein (BiP), and a novel putative escort chaperone endoplasmic reticulum protein 29 KDa (ERp29) were found to be associated with Tg, which might be interpreted as the contribution of the quality control machinery to the previously shown retention of Tg in the ER. We have extended our earlier observations of ER chaperone induction with the identification of the additional ER (ERp29, ERp72, calreticulin, protein disulfide isomerase (PDI)), cytoplasmic (heat shock protein (HSP)70, HSP90) and mitochondrial (mtHSP70) upregulated chaperones and folding enzymes. Activation of the transcriptional arm of UPR, as judged by the appearance of the spliced (active) form of X-box binding protein (XBP1) and processed activating transcription factor 6 (ATF6) transcription factors was suggested to contribute to the overexpression of the ER chaperones. The processing of ATF6 was observed in both human and rat tissues with Tg mutations. Whereas, in human tissues, weak splicing of XBP1 mRNA was detected only in the C1264R mutant, all rat thyroids including wild-type contained significant amounts of the spliced form of XBP1 as opposed to human liver and rat brain tissues, implying the existence of a previously unknown tissue-specific regulation of XBP1 processing.
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4.
  • Bjornstrom, L, et al. (författare)
  • Cross-talk between Stat5b and estrogen receptor-alpha and -beta in mammary epithelial cells
  • 2001
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 27:1, s. 93-106
  • Tidskriftsartikel (refereegranskat)abstract
    • Both 17beta-estradiol and prolactin play important roles in the mammary gland, raising the possibility of functional cross-talk between the two signaling pathways. Here, we demonstrate that estrogen receptor-alpha (ERalpha) and -beta (ERbeta) are both able to potentiate transcription from a Stat5-responsive promoter when activated by prolactin. Potentiation was observed not only in the presence of 17beta-estradiol, but also in the presence of anti-estrogens such as tamoxifen and ICI 182,780. The magnitude of the response was dependent on cell-type: in the HC11 mouse mammary epithelial cell line ERbeta potentiates transcription efficiently whereas ERalpha showed low activity. Conversely, in COS-7 cells, both estrogen receptors were active. We show that activation domains in the N-terminus (AF-1) and the C-terminus (AF-2) of the ERs are dispensable for potentiation. The effects are dependent on the presence of an intact DNA-binding/hinge domain, which we show is capable of interacting with Stat5b in vitro and in HC11 cell extracts. We conclude that ERalpha and ERbeta act as coactivators for Stat5b through a mechanism which is independent of AF-1 and AF-2.
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5.
  • Cardoso, Joao C. R., et al. (författare)
  • Corticotropin-releasing hormone family evolution : five ancestral genes remain in some lineages
  • 2016
  • Ingår i: Journal of Molecular Endocrinology. - 0952-5041 .- 1479-6813. ; 57:1, s. 73-86
  • Tidskriftsartikel (refereegranskat)abstract
    • The evolution of the peptide family consisting of corticotropin-releasing hormone ( CRH) and the three urocortins ( UCN1-3) has been puzzling due to uneven evolutionary rates. Distinct gene duplication scenarios have been proposed in relation to the two basal rounds of vertebrate genome doubling ( 2R) and the teleost fish-specific genome doubling ( 3R). By analyses of sequences and chromosomal regions, including many neighboring gene families, we show here that the vertebrate progenitor had two peptide genes that served as the founders of separate subfamilies. Then, 2R resulted in a total of five members: one subfamily consists of CRH1, CRH2, and UCN1. The other subfamily contains UCN2 and UCN3. All five peptide genes are present in the slowly evolving genomes of the coelacanth Latimeria chalumnae ( a lobe-finned fish), the spotted gar Lepisosteus oculatus ( a basal ray-finned fish), and the elephant shark Callorhinchus milii ( a cartilaginous fish). The CRH2 gene has been lost independently in placental mammals and in teleost fish, but is present in birds ( except chicken), anole lizard, and the nonplacental mammals platypus and opossum. Teleost 3R resulted in an additional surviving duplicate only for crh1 in some teleosts including zebrafish ( crh1a and crh1b). We have previously reported that the two vertebrate CRH/UCN receptors arose in 2R and that CRHR1 was duplicated in 3R. Thus, we can now conclude that this peptide-receptor system was quite complex in the ancestor of the jawed vertebrates with five CRH/UCN peptides and two receptors, and that crh and crhr1 were duplicated in the teleost fish tetraploidization.
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6.
  • Cen, Jing, et al. (författare)
  • Mechanisms of beneficial effects of metformin on fatty acid-treated human islets
  • 2018
  • Ingår i: Journal of Molecular Endocrinology. - 0952-5041 .- 1479-6813. ; 61:3, s. 91-99
  • Tidskriftsartikel (refereegranskat)abstract
    • Elevated levels of palmitate accentuate glucose-stimulated insulin secretion (GSIS) after short-term and cause beta-cell dysfunction after prolonged exposure. We investigated whether metformin, the first-line oral drug for treatment of T2DM, has beneficial effects on FFA-treated human islets and the potential mechanisms behind the effects. Insulin secretion, oxygen consumption rate (OCR), AMPK activation, endoplasmic reticulum (ER) stress and apoptosis were examined in isolated human islets after exposure to elevated levels of palmitate in the absence or presence of metformin. Palmitate exposure doubled GSIS after 2 days but halved after 7 days compared with control. Inclusion of metformin during palmitate exposure normalized insulin secretion both after 2 and 7 days. After 2-day exposure to palmitate, OCR and the marker of the adaptive arm of ER stress response (sorcin) were significantly raised, whereas AMPK phosphorylation, markers of pro-apoptotic arm of ER stress response (p-EIF2α and CHOP) and apoptosis (cleaved caspase 3) were not affected. Presence of metformin during 2-day palmitate exposure normalized OCR and sorcin levels. After 7-day exposure to palmitate, OCR and sorcin were not significantly different from control level, p-AMPK was reduced and p-EIF2α, CHOP and cleaved caspase 3 were strongly upregulated. Presence of metformin during 7-day culture with palmitate normalized the level of p-AMPK, p-EIF2α, CHOP and cleaved caspase 3 but significantly increased the level of sorcin. Our study demonstrates that metformin prevents early insulin hypersecretion and later decrease in insulin secretion from palmitate-treated human islets by utilizing different mechanisms.
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9.
  • Chisalita, Ioana Simona, et al. (författare)
  • Human aortic smooth muscle cells are insulin resistant at the receptor level but sensitive to IGF1 and IGF2
  • 2009
  • Ingår i: Journal of Molecular Endocrinology. - 0952-5041 .- 1479-6813. ; 43:5-6, s. 231-239
  • Tidskriftsartikel (refereegranskat)abstract
    • Whether insulin, in physiological concentrations, has direct effects on vascular smooth muscle cells (VSMC) remains controversial. Our aim was to characterize the mechanism for insulin resistance in VSMCs. For comparison, effects of insulin-like growth factor (IGF)-I and IGF-II were also studied. Cultured human aortic smooth muscle cells (HASMC) were used. Receptor mRNA was analysed by quantitative RT-PCR and receptor protein by ELISA and Western Blot. The biological effects were studied by thymidine incorporation and glucose accumulation. In HASMC both mRNA and protein expression of IGF-I receptors (IGF-IR) were 5 fold higher compared to insulin receptor (IR). IR isoform A mRNA was 13 times more expressed than IR isoform B. Immunoprecipitation and Western blot showed co precipitation of IR and IGF-IR indicating the presence of hybrid IR/IGF-IR. Phosphorylation of the IGF-IR β-subunit was obtained by IGF-I 10-9-10-8mol l-1 and IGF-II 10-8mol l-1. IR β-subunit was phosphorylated by IGF-I 10-8mol l-1 but not by insulin. IGF-I stimulated IRS-I at 10-8mol l-1, Akt and Erk 1/2 at 10-9-10-8mol l-1, respectively. IGF-II stimulated Akt at 10-8mol l-1 whereas insulin had no effect. IGF-I and IGF-II at a concentration of 10-8-10-7mol l-1 significantly stimulated 3H-thymidine incorporation, whereas insulin did not. 14C-Glucose accumulation was stimulated by IGF-I or IGF-II 10-8-10-7mol l-1, and also by insulin 10-7mol l-1. Our results suggest that IGF-IR and hybrid IR/IGF-IR are activated by physiological concentrations of IGF-I and IGF-II in HASMC and this causes downstream signaling and biological effects, while insulin has no effect on its receptor or downstream signaling probably due to a preponderance of IGF-IR and incorporation of IR into hybrid IR/IGF-IR.
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10.
  • Dare, E, et al. (författare)
  • Characterization of the phosphatidylinositol-specific phospholipase C isozymes present in the bovine parathyroid and in human kidney HEK293 cells stably transfected with the human parathyroid Ca2+-sensing receptor
  • 1998
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 21:1, s. 7-17
  • Tidskriftsartikel (refereegranskat)abstract
    • The regulation of parathyroid hormone secretion by the chief cells of the parathyroid is mediated by a 7-transmembrane (7-TM) Ca2+-sensing receptor (CaR), which signals via activation of pertussis toxin-insensitive G proteins, causing stimulation of phosphatidylinositol-specific phospholipase C (PI-PLC). We have identified the PI-PLC isoforms expressed in two model systems utilized for studying CaR signal transduction, i.e. dispersed bovine parathyroid cells and a human embryonic kidney cell line (HEK 293) stably transfected with the human parathyroid CaR-cDNA. All of the eight PI-PLC isozymes examined in this study were found to be expressed to varying extents in the bovine parathyroid gland and in the CaR-transfected HEK cells as assessed by immunoblotting. We localized the expression of the more abundant isozymes (beta1, beta2, beta3, gamma1, gamma2, delta2) to the chief cells of the bovine parathyroid by immunocytochemistry, while the two less abundant isozymes (delta1, beta4) were not detectable in parathyroid sections. G proteins activated by 7-TM receptors are known to activate mainly PI-PLC of the beta class. Therefore, beta1, beta2, beta3 and beta4, all expressed in the bovine parathyroid, are candidate isozymes for coupling to the CaR. A comparison of the levels of expression of PI-PLC isozymes between CaR-transfected HEK cells and non-transfected HEK cells suggested that the expression of the CaR in this human cell line does not cause a significant up-regulation of any of the PLCbeta and PLCgamma isozymes. PLCdelta2, showing predominantly nuclear localization in the parathyroid, was the sole PI-PLC isozyme with higher levels of expression in CaR-transfected HEK cells.
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11.
  • Dekker Nitert, Marloes, et al. (författare)
  • CaV1.2 rather than CaV1.3 is coupled to glucose-stimulated insulin secretion in INS-1 832/13 cells.
  • 2008
  • Ingår i: Journal of Molecular Endocrinology. - 1479-6813. ; 41:1, s. 1-11
  • Tidskriftsartikel (refereegranskat)abstract
    • In clonal beta-cell lines and islets from different species, a variety of calcium channels are coupled to glucose-stimulated insulin secretion. The aim of this study was to identify the voltage-gated calcium channels that control insulin secretion in insulinoma (INS)-1 832/13 cells. The mRNA level of Ca(V)1.2 exceeded that of Ca(V)1.3 and Ca(V)2.3 two-fold. Insulin secretion, which rose tenfold in response to 16.7 mM glucose, was completely abolished by 5 microM isradipine that blocks Ca(V)1.2 and Ca(V)1.3. Similarly, the increase in intracellular calcium in response to 15 mM glucose was decreased in the presence of 5 microM isradipine, and the frequency of calcium spikes was decreased to the level seen at 2.8 mM glucose. By contrast, inhibition of Ca(V)2.3 with 100 nM SNX-482 did not significantly affect insulin secretion or intracellular calcium. Using RNA interference, Ca(V)1.2 mRNA and protein levels were knocked down by approximately 65% and approximately 34% respectively, which reduced insulin secretion in response to 16.7 mM glucose by 50%. Similar reductions in calcium currents and cell capacitance were seen in standard whole-cell patch-clamp experiments. The remaining secretion of insulin could be reduced to the basal level by 5 microM isradipine. Calcium influx underlying this residual insulin secretion could result from persisting Ca(V)1.2 expression in transfected cells since knock-down of Ca(V)1.3 did not affect glucose-stimulated insulin secretion. In summary, our results suggest that Ca(V)1.2 is critical for insulin secretion in INS-1 832/13 cells.
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14.
  • Elebring, Erik, 1990, et al. (författare)
  • βHB inhibits glucose-induced GLP-1 secretion in GLUTag and human jejunal enteroids
  • 2023
  • Ingår i: Journal of molecular endocrinology. - 1479-6813. ; 70:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Ingestion of nutrients stimulates incretin secretion from enteroendocrine cells (EECs) of the epithelial layer of the gut. Glucagon-like peptide-1 (GLP-1) is one of these incretins that stimulate postprandial insulin release and signal satiety to the brain. Understanding the regulation of incretin secretion might open up new therapeutic options for obesity and type-2 diabetes mellitus. To investigate the inhibitory effect of the ketone body β-hydroxybutyrate (βHB) on glucose-induced GLP-1 secretion from EECs, in vitro cultures of murine GLUTag cells and differentiated human jejunal enteroid monolayers were stimulated with glucose to induce GLP-1 secretion. The effect of βHB on GLP-1 secretion was studied using ELISA and ECLIA methods. GLUTag cells stimulated with glucose and βHB were analysed using global proteomics focusing on cellular signalling pathways and the results were verified by Western blot. Results demonstrated βHB had a significant inhibitory effect on glucose-induced GLP-1 secretion at a dose of 100 mM in GLUTag cells. In differentiated human jejunal enteroid monolayers, glucose-induced secretion of GLP-1 was inhibited at a much lower dose of 10 mM βHB. The addition of βHB to GLUTag cells resulted in decreased phosphorylation of kinase AKT and transcription factor STAT3 and also influenced the expressions of signalling molecule IRS-2, kinase DGKε and receptor FFAR3. In conclusion, βHB displays an inhibitory effect on glucose-induced GLP-1 secretion in vitro in GLUTag cells and in differentiated human jejunal enteroid monolayers. This effect may be mediated through multiple downstream mediators of G-protein coupled receptor activation, such as PI3K signalling.
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16.
  • Essand, Magnus, et al. (författare)
  • Identification and characterization of a novel splicing variant of vesicular monoamine transporter 1
  • 2005
  • Ingår i: Journal of Molecular Endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 35:3, s. 489-501
  • Tidskriftsartikel (refereegranskat)abstract
    • Vesicular monoamine transporter 1 (VMAT1) is an integral protein in the membrane of secretory vesicles of neuroendocrine and endocrine cells that allows the transport of biogenic monoamines, such as serotonin, from the cytoplasm into the secretory vesicles. The full-length VMAT1 transcript is produced from 16 exons. We have identified and characterized an alternatively spliced form of VMAT1 that lacks exon 15, the next to last exon of VMAT1. The new form was therefore denoted VMAT1Delta15. Exon 15 does not contain an even multiple of three nucleotides. As a consequence, there is a shift of reading frame, and exon 16 is translated in an alternative reading frame, yielding a novel protein with a shorter and unrelated C-terminus compared with the native VMAT1 protein. VMAT1 and VMAT1Delta15 mRNAs are simultaneously expressed in normal and neoplastic neuroendocrine cells of the GI tract. However, VMAT1 expression is always higher than VMAT1Delta15 expression. We prove that VMAT1Delta15 is not localized in large, dense core vesicles as the native form but in the endoplasmic reticulum. Furthermore, while VMAT1 can take up serotonin, VMAT1Delta15 cannot, indicating different functions for the two forms of VMAT1.
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17.
  • Fagman, Henrik, 1975, et al. (författare)
  • Morphogenetics of early thyroid development.
  • 2010
  • Ingår i: Journal of molecular endocrinology. - 1479-6813.
  • Forskningsöversikt (refereegranskat)abstract
    • The thyroid develops from the foregut endoderm. Yet uncharacterized inductive signals specify endoderm progenitors to a thyroid cell fate that assemble in the pharyngeal floor from which the primordium buds and migrates to the final position of the gland. The morphogenetic process is regulated by both cell-autonomous (activated by e.g. Nkx2-1, Foxe1, Pax8 and Hhex) and mesoderm-derived (mediated by e.g. Tbx1 and Fgf) mechanisms acting in concert to promote growth and survival of progenitor cells. The developmental role of thyroid-stimulating hormone is limited to thyroid differentiation set to work after the gross anatomy of the gland is already sculptured. This review summarizes recent advances on the molecular genetics of thyroid morphogenesis put into context of endoderm developmental traits and highlights established and potentially novel mechanisms of thyroid dysgenesis of relevance to congenital hypothyroidism in man.
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18.
  • Fagman, Henrik, 1975, et al. (författare)
  • Morphogenetics of early thyroid development.
  • 2011
  • Ingår i: Journal of molecular endocrinology. - 1479-6813. ; 46:1
  • Forskningsöversikt (refereegranskat)abstract
    • The thyroid develops from the foregut endoderm. Yet uncharacterized inductive signals specify endoderm progenitors to a thyroid cell fate that assembles in the pharyngeal floor from which the primordium buds and migrates to the final position of the gland. The morphogenetic process is regulated by both cell-autonomous (e.g. activated by NKX2-1, FOXE1, PAX8, and HHEX) and mesoderm-derived (e.g. mediated by TBX1 and fibroblast growth factors) mechanisms acting in concert to promote growth and survival of progenitor cells. The developmental role of TSH is limited to thyroid differentiation set to work after the gross anatomy of the gland is already sculptured. This review summarizes recent advances on the molecular genetics of thyroid morphogenesis put into context of endoderm developmental traits and highlights established and novel mechanisms of thyroid dysgenesis of potential relevance to congenital hypothyroidism in man.
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19.
  • Fridmanis, Davids, et al. (författare)
  • Replacement of short segments within transmembrane domains of MC2R disrupts retention signal
  • 2014
  • Ingår i: Journal of Molecular Endocrinology. - 0952-5041 .- 1479-6813. ; 53:2, s. 201-215
  • Tidskriftsartikel (refereegranskat)abstract
    • The proteolysis of the pro-opiomelanocortin precursor results in the formation of melanocortins (MCs), a group of peptides that share the conserved -H-F-R-W- sequence, which acts as a pharmacophore for five subtypes of MC receptors (MCRs). MC type 2 receptor (MC2R; also known as ACTHR) is the most specialized of all the MCRs. It is predominantly expressed in the adrenal cortex and specifically binds ACTH. Unlike other MCRs, it requires melanocortin receptor accessory protein 1 (MRAP) for formation of active receptor and for its transport to the cell membrane. The molecular mechanisms underlying this specificity remain poorly understood. In this study, we used directed mutagenesis to investigate the role of various short MC2R sequence segments in receptor membrane trafficking and specific activation upon stimulation with ligands. The strategy of the study was to replace two to five amino acid residues within one MC2R segment with the corresponding residues of MC4R. In total, 20 recombinant receptors C-terminally fused to enhanced green fluorescent protein were generated and their membrane trafficking efficiencies and cAMP response upon stimulation with α-MSH and ACTH(1-24) were estimated during their stand-alone expression and coexpression with MRAP. Our results indicate that both the motif that determines the ligand-recognition specificity and the intracellular retention signal are formed by a specific extracellular structure, which is supported by the correct alignment of the transmembrane domains. Our results also indicate that the aromatic-residue-rich segment of the second extracellular loop is involved in the effects mediated by the second ACTH pharmacophore (-K-K-R-R-).
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20.
  • Gachkar, Sogol, et al. (författare)
  • Aortic effects of thyroid hormone in male mice
  • 2019
  • Ingår i: Journal of Molecular Endocrinology. - 1479-6813. ; 62:3, s. 91-99
  • Tidskriftsartikel (refereegranskat)abstract
    • It is well established that thyroid hormones are required for cardiovascular functions; however, the molecular mechanisms remain incompletely understood, especially the individual contributions of genomic and non-genomic signalling pathways. In this study, we dissected how thyroid hormones modulate aortic contractility. To test the immediate effects of thyroid hormones on vasocontractility, we used a wire myograph to record the contractile response of dissected mouse aortas to the adrenergic agonist phenylephrine in the presence of different doses of T3 (3,3',5-triiodothyronine). Interestingly, we observed reduced vasoconstriction under low and high T3 concentrations, indicating an inversed U-shaped curve with maximal constrictive capacity at euthyroid conditions. We then tested for possible genomic actions of thyroid hormones on vasocontractility by treating mice for 4 days with 1 mg/L thyroxine in drinking water. The study revealed that in contrast to the non-genomic actions the aortas of these animals were hyperresponsive to the contractile stimulus, an effect not observed in endogenously hyperthyroid TRβ knockout mice. To identify targets of genomic thyroid hormone action, we analysed aortic gene expression by microarray, revealing several altered genes including the well-known thyroid hormone target gene hairless. Taken together, the findings demonstrate that thyroid hormones regulate aortic tone through genomic and non-genomic actions, although genomic actions seem to prevail in vivo. Moreover, we identified several novel thyroid hormone target genes that could provide a better understanding of the molecular changes occurring in the hyperthyroid aorta.
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21.
  • Gardmo, C, et al. (författare)
  • In vivo transfection of rat liver discloses binding sites conveying GH-dependent and female-specific gene expression
  • 2006
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 37:3, s. 433-441
  • Tidskriftsartikel (refereegranskat)abstract
    • The sexually dimorphic mode of GH secretion leads to a sex-differentiated expression of many hepatic target genes. Expression of the a1bg gene in rat liver is specifically induced by the female pattern of GH secretion. In this study, we have used the a1bg promoter in in vivo transfection experiments to investigate molecular mechanisms of GH-mediated female-specific hepatic gene regulation. Rat liver transfection was achieved by rapid tail vein injection of large volumes of plasmid solution. Expression of reporter constructs showed that the 160 bp proximal part of the a1bg promoter contained elements directing sex-specific expression. In vitro footprinting analysis and electromobility shift assays identified binding of hepatic nuclear factor 6 (HNF6), signal transducer and activator of transcriptions (Stat5) and nuclear factor 1 (NF1) in liver nuclear extracts to the 160 bp proximal promoter. Transfection of mutated and/or deletion constructs showed that HNF6 and NF1 binding markedly enhanced expression in female livers, whereas Stat5 reduces the sex difference by enhancing expression more strongly in male than in female rat liver. Based on our present results, we propose that adjacent binding sites for NF1 and HNF6 constitute a gene regulatory unit of importance for transducing the female-specific effect of GH in rat liver.
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23.
  • Giandomenico, Valeria, et al. (författare)
  • Olfactory Receptor 51E1 as a Novel Target for Diagnosis in Somatostatin Receptor Negative Lung Carcinoids
  • 2013
  • Ingår i: Journal of Molecular Endocrinology. - 0952-5041 .- 1479-6813. ; 51, s. 277-286
  • Tidskriftsartikel (refereegranskat)abstract
    • Somatostatin receptors (SSTRs) may be used in lung carcinoids (LCs) for diagnosis and therapy, although additional targets are clearly warranted. This study aimed to investigate whether olfactory receptor 51E1 (OR51E1) may be a potential target for LCs. OR51E1 coding sequence was analyzed in LC cell lines, NCI-H727 and NCI-H720. OR51E1 transcript expression was investigated in LC cell lines and frozen specimens by quantitative real-time PCR. OR51E1, SSTR2, SSTR3, and SSTR5 expression was evaluated by immunohistochemistry on paraffin-embedded sections of 73 typical carcinoids (TCs), 14 atypical carcinoids (ACs) and 11 regional/distant metastases, and compared to OctreoScan data. Immunohistochemistry results were rendered semiquantitatively on a scale from 0 to 3+, taking into account the cellular compartmentalization (membrane vs. cytoplasm) and the percentage of tumor cells (<50% vs. >50%). Our results showed that wild-type OR51E1 transcript was expressed in both LC cell lines. OR51E1 mRNA was expressed in 9/12 TCs and 7/9 ACs (p=NS). Immunohistochemically, OR51E1, SSTR2, SSTR3 and SSTR5 were detected in 85%, 71%, 25% and 39% of TCs, and in 86%, 79%, 43% and 36% of ACs, respectively. OR51E1 immunohistochemical scores were higher or equal compared to SSTRs in 79% of TCs and 86% of ACs. Furthermore, in the LC cases where all SSTR subtypes were lacking, membrane OR51E1 expression was detected in 10/17 TCs and 1/2 ACs. Moreover, higher OR51E1 immunohistochemical scores were detected in 5/6 OctreoScan-negative LC lesions. Therefore, the high expression of OR51E1 in LCs makes it a potential novel diagnostic target in SSTR-negative tumors.
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24.
  • Gormand, Amelie, et al. (författare)
  • LKB1 signalling attenuates early events of adipogenesis and responds to adipogenic cues.
  • 2014
  • Ingår i: Journal of Molecular Endocrinology. - 1479-6813. ; 53:1, s. 117-130
  • Tidskriftsartikel (refereegranskat)abstract
    • cAMP-response element-binding protein (CREB) is required for the induction of adipogenic transcription factors such as CCAAT/enhancer-binding proteins (C/EBPs). Interestingly, it is known from other tissues that LKB1 and its substrates AMP-activated protein kinase (AMPK) and salt-inducible kinases (SIKs), negatively regulate gene expression by phosphorylating the CREB co-activator CRTC2 and class IIa histone deacetylases (HDACs), which results in their exclusion from the nucleus where they co-activate or inhibit their targets. In this study, we show that AMPK/SIK signalling is acutely attenuated during adipogenic differentiation of 3T3-L1 preadipocytes, which coincides with dephosphorylation and nuclear translocation of CRTC2 and HDAC4. When subjected to differentiation, 3T3-L1 preadipocytes in which LKB1 expression was stably reduced using shRNA (LKB1-shRNA), as well as LKB1 knockout mouse embryonic fibroblasts (LKB1-/- MEFs), differentiated more readily into adipocyte-like cells and accumulated more triglycerides compared to scrambled-shRNA 3T3-L1 cells or Wt MEFs. In addition, the phosphorylation of CRTC2 and HDAC4 was reduced, and the mRNA expression of adipogenic transcription factors C/EBPα, peroxisome proliferator-activated receptor γ (PPARγ) and adipocyte-specific proteins such as hormone sensitive lipase (HSL), fatty acid synthase (FAS), aP2, Glut4 and adiponectin was increased in the absence of LKB1. The mRNA and protein expression of CHOP-10, a dominant negative member of the C/EBP family, was reduced in LKB1 shRNA expressing cells, providing a potential mechanism for the up-regulation of Pparg and Cebpa. These results support the hypothesis that LKB1 signalling keeps preadipocytes in their non-differentiated form.
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25.
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26.
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27.
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28.
  • Karger, Stefan, et al. (författare)
  • Distinct pattern of oxidative DNA damage and DNA repair in follicular thyroid tumours.
  • 2012
  • Ingår i: Journal of molecular endocrinology. - 1479-6813. ; 48:3, s. 193-202
  • Tidskriftsartikel (refereegranskat)abstract
    • Increased oxidative stress has been linked to thyroid carcinogenesis. In this paper, we investigate whether oxidative DNA damage and DNA repair differ in follicular adenoma (FA) and follicular thyroid carcinoma (FTC). 7,8-Dihydro-8-oxoguanine (8-OxoG) formation was analysed by immunohistochemistry in 46 FAs, 52 FTCs and 18 normal thyroid tissues (NTs). mRNA expression of DNA repair genes OGG1, Mut Y homologue (MUTYH) and endonuclease III (NTHL1) was analysed by real-time PCR in 19 FAs, 25 FTCs and 19 NTs. Induction and repair of oxidative DNA damage were studied in rat FRTL-5 cells after u.v. irradiation. Moreover, activation of DNA damage checkpoints (ataxia telangiectasia mutated (ATM) and H2A histone family, member X (H2AFX (H2AFX))) and proliferation index (MIB-1) were quantified in 28 non-oxyphilic and 24 oxyphilic FTCs. Increased nuclear and cytosolic 8-OxoG formation was detected in FTC compared with follicular adenoma, whereby cytosolic 8-OxoG formation was found to reflect RNA oxidation. Significant downregulation of DNA repair enzymes was detected in FTC compared with FA. In vitro experiments mirrored the findings in FTC with oxidative stress-induced DNA checkpoint activation and downregulation of OGG1, MUTYH and NTHL1 in FRTL-5 cells, an effect that, however, was reversible after 24  h. Further analysis of FTC variants showed decreased oxidative DNA damage, sustained checkpoint activation and decreased proliferation in oxyphilic vs non-oxyphilic FTC. Our data suggest a pathophysiological scenario of accumulating unrepaired DNA/RNA damage in FTC vs counterbalanced DNA/RNA damage and repair in FA. Furthermore, this study provides the first evidence for differences in oxidative stress defence in FTC variants with possible implications for therapeutic response and prognostic outcome.
  •  
29.
  • Kasper, S, et al. (författare)
  • Selective activation of the probasin androgen-responsive region by steroid hormones
  • 1999
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 22:3, s. 313-325
  • Tidskriftsartikel (refereegranskat)abstract
    • Glucocorticoid and androgen receptors have been shown to function through the same palindromic glucocorticoid response element (GRE) and yet have differential effects on gene transcription. In this study, we examined the functional and structural relationship of the androgen and glucocorticoid receptors with the androgen responsive region (ARR) of the probasin (PB) gene containing two androgen receptor binding sites, ARBS-1 and ARBS-2. Transfection studies indicated that one copy of each cis-acting DNA element was essential for maximal androgen-induced chloramphenicol acetyltransferase (CAT) activity and that androgen selectivity was maintained when multiple copies of the minimal wild type (wt) androgen responsive region containing both ARBS-1 and ARBS-2 (-244 to -96) were subcloned in front of the thymidine kinase promoter. Furthermore, replacing the androgen response region with 1, 2 or 3 copies of either ARBS-1 or ARBS-2 restored less than 4% of the biological activity seen with the wt PB ARR. Multiple copies of either ARBS-1 or ARBS-2 did not result in glucocorticoid-induced CAT gene activity. By comparison, 1 or 2 copies of the tyrosine aminotransferase (TAT) GRE, as well as the mouse mammary tumour virus GRE, were strong inducers of CAT activity in response to both androgen and glucocorticoid treatment. In addition, band shift assays demonstrated that although the synthetic glucocorticoid receptor, GR-DNA binding domain (GR-DBD), and the synthetic androgen receptor, AR2, could interact with the TAT GRE (dissociation constants Kd of 63.9 and 14.1 respectively), only AR2 but not GR-DBD binding could be detected on ARBS-1 and ARBS-2. Our findings provide further evidence that androgen-induced regulation of gene transcription can occur through androgen-specific DNA binding sites that are distinct from the common GRE.
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30.
  • Knuuttila, M., et al. (författare)
  • Applying mass spectrometric methods to study androgen biosynthesis and metabolism in prostate cancer
  • 2019
  • Ingår i: Journal of molecular endocrinology. - 1479-6813. ; 62:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent development of gas chromatography and liquid chromatography-tandem mass spectrometry (GC-MS/MS, LC-MS/MS) has provided novel tools to define sex steroid concentrations. These new methods overcome several of the problems associated with immunoassays for sex steroids. With the novel MS-based applications we are now able to measure small concentrations of the steroid hormones reliably and with high accuracy in both body fluids and tissue homogenates. The sensitivity of the tandem mass spectrometry assays allows us also for the first time to reliably measure picomolar or even femtomolar concentrations of estrogens and androgens. Furthermore, due to a high sensitivity and specificity of MS technology, we are also able to measure low concentrations of steroid hormones of interest in the presence of pharmacological concentration of other steroids and structurally closely related compounds. Both of these features are essential for multiple preclinical models for prostate cancer. The MS assays are also valuable for the simultaneous measurement of multiple steroids and their metabolites in small sample volumes in serum and tissue biopsies of prostate cancer patients before and after drug interventions. As a result, novel information about steroid hormone synthesis and metabolic pathways in prostate cancer has been obtained. In our recent studies, we have extensively applied a GC-MS/MS method to study androgen biosynthesis and metabolism in VCaP prostate cancer xenografts in mice. In the present review, we shortly summarize some of the benefits of the GC-MS/MS and novel LC-MS/MS assays, and provide examples of their use in defining novel mechanisms of androgen action in prostate cancer.
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31.
  • Larsson, Dennis, et al. (författare)
  • Antagonistic effects of 24R,25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3 on L-type Ca2+ channels and Na+/Ca2+ exchange in enterocytes from Atlantic cod (Gadus morhua).
  • 2002
  • Ingår i: Journal of Molecular Endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 28:1, s. 53-68
  • Tidskriftsartikel (refereegranskat)abstract
    • There is mounting evidence that vitamin D and its metabolites play important roles in regulating plasma calcium concentrations in teleost fish as in other vertebrates. The aims of the present study were to elucidate the possible cellular target mechanisms for the rapid actions of 24R,25(OH)(2)D(3), 25(OH)D(3) and 1,25(OH)(2)D(3) in Atlantic cod enterocytes at physiological doses, and to establish the concentration and thus the physiological range of circulating 24R,25(OH)(2)D(3), 25(OH)D(3) and 1,25(OH)(2)D(3) in the Atlantic cod. The plasma concentrations of 25(OH)D(3), 1,25(OH)(2)D(3) and 24R,25(OH)(2)D(3) were 15.3 +/- 2.7nM, 125.1 +/- 12.3pM and 10.1 +/- 23.5nM respectively. Exposure of enterocytes to 10mM calcium (Ca(2+)) evoked an increase in intracellular Ca(2+) concentrations ([Ca(2+)](i)). This increase was suppressed by 24R,25(OH)(2)D(3) dose-dependently, with an EC(50) of 4.9nM and a maximal inhibition of 60%. 24R,25(OH)(2)D(3) (20nM) abolished an increase in [Ca(2+)](i) (approximately 252%) in the control enterocytes exposed to 10microM S(-)-BAYK-8644, suggesting that the hormone acts by inhibiting Ca(2+) entry through L-type voltage-gated Ca(2+) channels. Administration of 20nM 24R,25(OH)(2)D(3) to enterocytes in the absence of extracellular Ca(2+) increased [Ca(2+)](i) by approximately 20%, indicating a release of Ca(2+) from intracellular stores. Administration of 25(OH)D(3) (20nM) resulted in a biphasic change in the enterocyte [Ca(2+)](i): within 1--5s, it decreased to 87 +/- 12nM below its mean basal [Ca(2+)](i) (334 +/- 13nM), followed by a rapid recovery of [Ca(2+)](i) to a new level, 10% lower than the initial [Ca(2+)](i). The rapid decrease, the recovery rate and the final [Ca(2+)](i) were all affected dose-dependently by 25(OH)D(3), with EC(50) values of 8.5, 17.0 and 18.9nM respectively. Furthermore, the effects of 25(OH)D(3) were sensitive to sodium (Na(+)), bepridil (10microM) and nifedipine (5 microM), suggesting that 25(OH)D(3) regulates the activity of both basolateral membrane-associated Na(+)/Ca(2+) exchangers and brush border membrane-associated L-type Ca(2+) channels. Administration of 25(OH)D(3) (10nM) to enterocytes in the absence of extracellular Ca(2+) increased [Ca(2+)](i) by approximately 18%, indicating a release of Ca(2+) from intracellular stores. 1,25(OH)(2)D(3) also affected enterocyte [Ca(2+)](i) in a biphasic manner: the rapid decrease, the recovery rate, and the mean final [Ca(2+)](i) were all affected dose-dependently, with EC(50) values of 8.3, 24.5 and 7.7nM respectively. The high EC(50) values for 1,25(OH)(2)D(3) compared with circulating concentrations of 1,25(OH)(2)D(3) (130pM) suggest that this effect is pharmacological, rather than of physiological relevance in enterocyte Ca(2+) homeostasis of the Atlantic cod. It is concluded that 24R,25(OH)(2)D(3) has a physiological role in decreasing intestinal Ca(2+) uptake via inactivation of L-type Ca(2+) channels, whereas the physiological role of 25(OH)D(3) is to increase enterocyte Ca(2+) transport via activation of Na(+)/Ca(2+) exchangers, concurrent with activation of L-type Ca(2+) channels.
  •  
32.
  • Lenhart, P.M., et al. (författare)
  • G-protein-coupled receptor 30 interacts with receptor activity-modifying protein 3 and confers sex-dependent cardioprotection
  • 2013
  • Ingår i: Journal of Molecular Endocrinology. - 1479-6813. ; 51:1, s. 191-202
  • Tidskriftsartikel (refereegranskat)abstract
    • Abstract Receptor activity-modifying protein 3 (RAMP3) is a single-pass transmembrane protein known to interact with and affect the trafficking of several G-protein-coupled receptors (GPCRs). We sought to determine whether RAMP3 interacts with GPR30, also known as G-protein-coupled estrogen receptor 1. GPR30 is a GPCR that binds estradiol and has important roles in cardiovascular and endocrine physiology. Using bioluminescence resonance energy transfer titration studies, co-immunoprecipitation, and confocal microscopy, we show that GPR30 and RAMP3 interact. Furthermore, the presence of GPR30 leads to increased expression of RAMP3 at the plasma membrane in HEK293 cells. In vivo, there are marked sex differences in the subcellular localization of GPR30 in cardiac cells, and the hearts of Ramp3(-/-) mice also show signs of GPR30 mislocalization. To determine whether this interaction might play a role in cardiovascular disease, we treated Ramp3(+)(/)(+) and Ramp3(-/-) mice on a heart disease-prone genetic background with G-1, a specific agonist for GPR30. Importantly, this in vivo activation of GPR30 resulted in a significant reduction in cardiac hypertrophy and perivascular fibrosis that is both RAMP3 and sex dependent. Our results demonstrate that GPR30-RAMP3 interaction has functional consequences on the localization of these proteins both in vitro and in vivo and that RAMP3 is required for GPR30-mediated cardioprotection.
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33.
  • Liu, Lian, et al. (författare)
  • Phosphorylation and inactivation of glycogen synthase kinase-3 by soluble kit ligand in mouse oocytes during early follicular development.
  • 2007
  • Ingår i: Journal of Molecular Endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 38:1-2, s. 137-146
  • Tidskriftsartikel (refereegranskat)abstract
    • Communication between mammalian oocytes and their surrounding granulosa cells through the Kit-Kit ligand (KL, or stem cell factor, SCF) system has been shown to be crucial for follicular development. Our previous studies (Reddy et al. 2005, Liu et al. 2006) have indicated that the intra-oocyte KL-Kit-PI3 kinase (PI3K)-Akt-Foxo3a cascade may play an important role in follicular activation and early development. In the present study, using in situ hybridization and in vitro culture of growing oocytes from 8-day-old postnatal mice, we have demonstrated that another Akt substrate, glycogen synthase kinase-3 (GSK-3), is expressed in growing oocytes. Also, treatment of cultured mouse oocytes with soluble KL not only leads to increased Akt kinase activity in the oocytes, which can phosphorylate recombinant GSK-3 in vitro, but also leads to phosphorylation of oocyte GSK-3alpha and GSK-3beta, which can result in the inactivation of GSK-3 function in oocytes. In addition, we have shown that the regulation of GSK-3alpha and GSK-3beta in cultured oocytes by soluble KL is accomplished through PI3K, since the PI3K-specific inhibitor LY294002 completely abolished the KL-induced phosphorylation of GSK-3alpha and GSK-3beta. Moreover, blockage of the Kit signaling pathway by a Kit function-blocking antibody, ACK2, resulted in reduced phosphorylation of GSK-3. Taken together, our data suggest that the cascade from granulosa cell-derived KL to Kit-PI3K-Akt-GSK-3 in oocytes may take part in regulation of oocyte growth and early ovarian follicular development.
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34.
  • Lu, Ming, et al. (författare)
  • Expression and association of TRPC subtypes with Orai1 and STIM1 in human parathyroid
  • 2010
  • Ingår i: Journal of Molecular Endocrinology. - 0952-5041 .- 1479-6813. ; 44:5, s. 285-294
  • Tidskriftsartikel (refereegranskat)abstract
    • The mechanism behind Ca2+ entry into the parathyroid cells has been widely debated, and the molecular identities of the responsible ion channels have not been established yet. In this study, we show that the parathyroid cells lack voltage-operated Ca2+ channels. Passive store depletion by thapsigargin, on the other hand, induces a large non-voltage-activated non-selective cation current. The increase in intracellular Ca2+ caused by thapsigargin is attenuated by 2-aminoethoxydiphenyl borate, a blocker of store-operated Ca2+ entry (SOCE). Candidate molecules for non-voltage-operated Ca2+ signaling were investigated. These included members of the transient receptor potential canonical (TRPC) ion channel family, as well as Ca2+ release-activated Ca2+ modulator 1 (Orai1) and stromal interaction molecule 1 (STIM1) that are key proteins in the SOCE pathway. Using RT-PCR screening, quantitative real-time PCR, and western blot, we showed expression of TRPC1, TRPC4, and TRPC6; Orai1; and STIM1 genes and proteins in normal and adenomatous human parathyroid tissues. Furthermore, co-immunoprecipitation experiments demonstrated a ternary complex of TRPC1-Orai1-STIM1, supporting a physical interaction between these molecules in human parathyroid.
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35.
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36.
  • Lundholm, Lovisa, et al. (författare)
  • Gene expression profiling identifies liver X receptor alpha as an estrogen-regulated gene in mouse adipose tissue.
  • 2004
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 32:3, s. 879-92
  • Tidskriftsartikel (refereegranskat)abstract
    • Estrogens reduce adipose tissue mass in both humans and animals. The molecular mechanisms for this effect are, however, not well characterized. We took a gene expression profiling approach to study the direct effects of estrogen on mouse white adipose tissue (WAT). Female ovariectomized mice were treated for 10, 24 and 48 h with 17beta-estradiol or vehicle. RNA was extracted from gonadal fat and hybridized to Affymetrix MG-U74Av2 arrays. 17beta-Estradiol was shown to decrease mRNA expression of liver X receptor (LXR) alpha after 10 h of treatment compared with the vehicle control. The expression of several LXRalpha target genes, such as sterol regulatory element-binding protein 1c, apolipoprotein E, phospholipid transfer protein, ATP-binding cassette A1 and ATP-binding cassette G1, was similarly decreased. We furthermore identified a 1.5 kb LXRalpha promoter fragment that is negatively regulated by estrogen. Several genes involved in lipogenesis and lipolysis were identified as novel targets that could mediate estrogenic effects on adipose tissue. Finally, we show that ERalpha is the main estrogen receptor expressed in mouse white adipose tissue (WAT) with mRNA levels several hundred times higher than those of ERbeta mRNA.
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37.
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38.
  • Nyblom, Hanna K, et al. (författare)
  • AMP-activated protein kinase agonist dose dependently improves function and reduces apoptosis in glucotoxic beta-cells without changing triglyceride levels
  • 2008
  • Ingår i: Journal of molecular endocrinology. - 1479-6813. ; 41:3, s. 187-94
  • Tidskriftsartikel (refereegranskat)abstract
    • Prolonged hyperglycaemia leads to impaired glucose-stimulated insulin secretion (GSIS) and apoptosis in insulin-producing beta-cells. The detrimental effects have been connected with glucose-induced lipid accumulation in the beta-cell. AMP-activated protein kinase (AMPK) agonist, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), promotes utilization of nutrient stores for energy production. It was tested how impaired GSIS and elevated apoptosis observed in insulinoma (INS)-1E cells after prolonged culture at 27 mM glucose were affected by the inclusion of 0.3 or 1 mM AICAR during culture. Glucose-induced impairment of insulin release was reverted by the inclusion of 0.3 but not 1 mM AICAR, which did not affect insulin content. The glucose-induced rise in triglyceride (TG) content observed in the cells cultured at 27 mM glucose was not altered by the inclusion of either 0.3 or 1 mM AICAR. Inclusion of 1 but not 0.3 mM AICAR during culture induced phosphorylation of AMPK and its downstream target acyl-CoA carboxylase. Phosphorylation was paralleled by reduced number of apoptotic cells and lowered expression of pro-apoptotic C/EBP homologous protein (CHOP). In conclusion, AICAR dose dependently improves beta-cell function and reduces apoptosis in beta-cells exposed to prolonged hyperglycaemia without changing TG levels.
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39.
  • Nygard, M, et al. (författare)
  • Thyroid hormone-mediated negative transcriptional regulation of Necdin expression
  • 2006
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 36:3, s. 517-530
  • Tidskriftsartikel (refereegranskat)abstract
    • Unliganded thyroid hormone receptors (apoTRs) repress transcription of hormone-activated genes by recruiting corepressors to the promoters. In contrast, on promoters containing so-called negative thyroid hormone response elements (nTREs), apoTRs activate transcription. A number of different molecular mechanisms have been described as to how apoTRs activate transcription varying with the target gene of the study. Here we demonstrate that thyroid hormone regulates the transcription of the Necdin gene, a developmentally regulated candidate gene for the genomic imprinting-associated neurobehavioural disorder, Prader–Willi syndrome. ApoTRs activate Necdin expression through an nTRE in its promoter, downstream of the transcription start site. The nTRE of the Necdin gene resembles the nTREs of the TSHβ genes of the hypothalamus–pituitary–thyroid axis in the sequence, position in the promoter, and mode of activation. We show that this group of nTRE-driven genes shares the requirements for binding of the retinoic X receptor and nuclear receptor corepressor/silencing mediator of retinoid and thyroid hormone receptors (NCoR/SMRT) for full ligand-independent activation, whereas there is no need for association of the p160 family of coactivators. In accordance with the requirement for corepressors, Necdin expression is influenced by deacetylase activity, suggesting that histone deacetylases and corepressors as well could function as activators of transcription, depending on the promoter context.
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40.
  • Palmieri, C, et al. (författare)
  • The expression of oestrogen receptor (ER)-beta and its variants, but not ERalpha, in adult human mammary fibroblasts
  • 2004
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 33:1, s. 35-50
  • Tidskriftsartikel (refereegranskat)abstract
    • Whilst oestrogen receptor (ER)-alpha and ERbeta have been shown to be important in the development of the mammary gland, the cell-specific expression pattern of these two receptors within the human breast is not clear. Although it is well established that in the developing rodent mammary gland stromal ERalpha mediates the secretion of growth factors which stimulate the proliferation of the ductal epithelium, the expression of ERalpha in human adult breast stromal fibroblasts is controversial, and the expression of ERbeta has not been properly defined. In the present study, we have evaluated the expression of ERalpha and ERbeta by immunohistochemistry in normal tissue samples, and in purified human breast fibroblasts by Western blotting, RT-PCR analysis and ligand-binding sucrose gradient assay. Our data clearly demonstrated that ERbeta variants, including ERbeta1, ERbeta2, ERbeta5, ERbetadelta and ERbetains, but not ERalpha, are expressed in human adult mammary fibroblasts. These results are supported by the findings that an ERbeta-selective ligand, BAG, but not the ERalpha high-affinity ligand oestradiol, can induce fibroblast growth factor-7 release and activate transcription from an oestrogen-responsive element promoter in these adult human mammary fibroblasts. Together, these observations revealed that, in the adult breast and in breast cancer, the proliferative signals derived from the stroma of adult mammary glands in response to oestrogen are not mediated by ERalpha and provide new insights into the nature of stromal-epithelial interactions in the adult mammary gland. In addition, the expression of these ERbeta variants in cells where there is no ERalpha suggested that these ERbeta splice forms may have functions other than that of modulating ERalpha activity.
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41.
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42.
  • Renlund, N, et al. (författare)
  • Induction of steroidogenesis in immature rat Leydig cells by interleukin-1alpha is dependent on extracellular signal-regulated kinases
  • 2006
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 36:2, s. 327-336
  • Tidskriftsartikel (refereegranskat)abstract
    • Interleukin-1α (IL-1α) plays an important role in the regulation of immune responses as well as in non-inflammatory events in different types of cells. Here we have investigated the involvement of the extracellular signal-regulated kinase (ERK) cascade in IL-1α-induced steroidogenesis by primary cultures of immature rat Leydig cells. Our findings indicate that protein kinase C functions as an upstream component of signal transduction from the IL-1 receptor type I (IL-1RI) to the ERK cascade. It was observed that IL-1α upregulated both steroidogenic acute regulatory (StAR) protein expression and its phosphorylation when compared with controls. Selective inhibition of these mitogen-activated protein kinases (MAPKs) by UO126 enhanced both the expression and phosphorylation of the StAR protein, but suppressed androgen production by the immature Leydig cells as well as dissipating the mitochondrial electrochemical potential (Ψm) in these cells. The evidence that water-soluble cholesterol but not 22R-hydroxycholesterol-stimulated steroidogenesis was inhibited by UO126 suggested that an intact Ψm across the inner mitochondrial membrane is required for cholesterol translocation and is positively regulated by the ERK cascade. We propose that activation of ERKs by IL-1α plays a dual role in the regulation of steroidogenesis in immature Leydig cells: these MAPKs downregulate StAR expression and phosphorylation, while at the same time they support an intact Ψm across the inner mitochondrial membrane, thereby promoting translocation of cholesterol into the mitochondria of the Leydig cell.
  •  
43.
  •  
44.
  • Seppänen-Laakso, Tuulikki, et al. (författare)
  • How to study lipidomes
  • 2009
  • Ingår i: Journal of Molecular Endocrinology. - : Society for Endocrinology. - 0952-5041 .- 1479-6813. ; 42:3, s. 185-190
  • Forskningsöversikt (refereegranskat)abstract
    • Lipidome is loosely defined as the entire spectrum of lipids in a biological system. Given the modern lipidomics platforms for the first time empower us with the ability to obtain a snapshot of complete cellular/organismal lipidome, many surprises and discoveries are likely awaiting us in the area of lipids as related to cellular/organismal physiology. The lipidomics approaches can be applied both as the phenotyping platform and for the hypothesis-driven research aiming to elucidate, e.g., a specific pathway or gene function. Modern lipidomics methods combine the latest mass spectrometry technology and bioinformatics methods with traditional methods such as for sample preparation and lipid extraction.
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45.
  •  
46.
  • Shi, Ruifeng, et al. (författare)
  • CLEC11A improves insulin secretion and promotes cell proliferation in human beta-cells
  • 2023
  • Ingår i: Journal of Molecular Endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 71:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Beta-cell dysfunction is a hallmark of disease progression in patients with diabetes. Research has been focused on maintaining and restoring beta-cell function during diabetes development. The aims of this study were to explore th e expression of C-type lectin domain containing 11A (CLEC11A), a secreted sulphated glycoprotein, in human islets and to evaluate the effects of CLEC11A on beta-cell funct ion and proliferation in vitro. To test these hypotheses, human islets and human EndoC-beta H1 cell line were used in this study. We identified that CLEC11A was expressed in beta-cells and alpha-cells in human islets but not in EndoC-beta H1 cells, whereas the receptor of CLEC11A called integrin subunit alpha 11 was found in both human islets and En doC-beta H1 cells. Long-term treatment with exogenous recombinant human CLEC11A (rhCLEC11A) accentuated glucose-stimulated insulin secretion, insulin content, and proliferation from human islets and EndoC-beta H1 cells, which was partially due to the accentuated expression levels of transcription factors MAFA and PDX1. However, the impaired beta-cell function and reduced mRNA expression of INS and MAFA in EndoC-beta H1 cells that were caused by chronic palmitate exposure could only be partially improved by the introduction of rhCLEC11A. Based on these results, we conclude that rhCLEC11A promotes insulin secretion, insulin content, and proliferation in human beta-cells, which are associated with the accentuated expression levels of transcription factors MAFA and PDX1. CLEC11A, therefore, may provide a novel therapeutic target for maintaining beta-cell function in patients with diabetes.
  •  
47.
  • Steffensen, KR, et al. (författare)
  • Genome-wide expression profiling; a panel of mouse tissues discloses novel biological functions of liver X receptors in adrenals
  • 2004
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 33:3, s. 609-622
  • Tidskriftsartikel (refereegranskat)abstract
    • The liver X receptors α and β (LXRα and LXRβ ) are members of the nuclear receptor superfamily of proteins which are highly expressed in metabolically active tissues. They regulate gene expression of critical genes involved in cholesterol catabolism and transport, lipid and triglyceride biosynthesis and carbohydrate metabolism in response to distinct oxysterols and intermediates in the cholesterol metabolic pathway. The biological roles of the LXRs in tissues other than liver, intestine and adipose tissue are poorly elucidated. In this study we used global gene-expression profiling analysis to detect differences in expression patterns in several tissues from mice fed an LXR agonist or vehicle. Our results show that LXR plays an important role in the kidney, lung, adrenals, brain, testis and heart where several putative LXR target genes were found. The effects of the LXRs were further analysed in adrenals where treatment with an LXR agonist induced expression of adrenocorticotrophic hormone receptor, suppressed expression of uncoupling protein (UCP)-1 and UCP-3 as well as several glycolytic enzymes and led to increased serum corticosterone levels. These results indicate novel biological roles of the LXR including regulation of energy metabolism, glycolysis and steroidogenesis in the adrenals via alteration of expression profiles of putative target genes.
  •  
48.
  • Svechnikov, K, et al. (författare)
  • Interleukin-1alpha stimulates steroidogenic acute regulatory protein expression via p38 MAP kinase in immature rat Leydig cells
  • 2003
  • Ingår i: Journal of molecular endocrinology. - : Bioscientifica. - 0952-5041 .- 1479-6813. ; 30:1, s. 59-67
  • Tidskriftsartikel (refereegranskat)abstract
    • We have investigated the involvement of the steroidogenic acute regulatory (StAR) protein in interleukin-1alpha (IL-1alpha)-induced steroidogenesis in immature (40-day-old) and adult Leydig cells in vitro. Further, IL-1alpha-mediated signaling pathway(s) controlling StAR expression in immature Leydig cells were also studied. IL-1alpha stimulated both androgen production and StAR protein expression in a dose- and time-dependent manner in immature but not adult Leydig cells. These effects of IL-1alpha were prevented by pretreatment of the cells with the specific inhibitors of the p38 MAP kinase, SB203580 and PD169316, suggesting that this kinase is an important part of IL-1alpha signaling in the immature Leydig cell. The present results suggest that IL-1alpha, which is constitutively produced by the rat testis from postnatal day 25, is an important paracrine regulator of postnatal Leydig cell maturation. Regulation of StAR protein expression is one of the possible mechanisms by which IL-1alpha contributes to the differentiation of immature Leydig cells into adult cells.
  •  
49.
  • Svensson, C (författare)
  • Effects of growth hormone in vitro on the glucose metabolism of fetal rat islet b-cells.
  • 1996
  • Ingår i: J Mol Endocrinol. - : Bioscientifica. ; 17:2, s. 131-138
  • Tidskriftsartikel (refereegranskat)abstract
    • This study was undertaken to investigate the effects of growth hormone (GH) on the in vitro maturation of the metabolism of fetal rat islets. For this purpose fetal islets were obtained from 21-day-old fetuses by mild collagenase digestion of the pancreas and cultured in RPMI 1640 supplemented with 10% fetal calf serum. After one day the medium was changed and supplemented with 1% fetal calf serum with or without GH (1 μg/ml, human recombinant) and the islets cultured for another two days. Islets were then studied with regard to insulin secretion, (pro)insulin and total protein biosynthesis, glucose utilization and oxidation, thymidine incorporation, insulin and DNA contents and the contents of mRNAs for either insulin, adenine nucleotide translocator or cytochrome b. In addition, the activities of glucose phosphorylating enzymes and succinate-cytochrome c reductase were measured. Islets treated with GH showed increased insulin secretion in response to glucose, increased rates of glucose oxidation and utilization, increased thymidine incorporation and increased activities of succinate cytochrome c reductase and glucose phosphorylation at high glucose concentrations. There were, however, no changes in (pro)insulin and total protein biosynthesis, contents of insulin and DNA or the contents of any of the mRNAs. These combined data show that fetal β-cells are sensitive to growth hormone with respect to glucose metabolism, insulin release and DNA replication. The increased rates of islet glucose phosphorylation may reflect glucokinase activity and explain part of the increased insulin responsiveness to glucose of the fetal rat β-cell. These observations suggest that GH is of physiological significance for the maturation of the fetal β-cell.
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50.
  • Svensson, Johan, 1964, et al. (författare)
  • Stimulation of both estrogen and androgen receptors maintains skeletal muscle mass in gonadectomized male mice but mainly via different pathways.
  • 2010
  • Ingår i: Journal of molecular endocrinology. - 1479-6813. ; 45:1, s. 45-57
  • Tidskriftsartikel (refereegranskat)abstract
    • Testosterone is a major regulator of muscle mass. Little is known whether this is due to a direct stimulation of the androgen receptor (AR) or mediated by aromatization of testosterone to estradiol (E(2)), the ligand for the estrogen receptors (ERs), in peripheral tissues. In this study, we differentiated between the effects mediated by AR and ER by treating orchidectomized (orx) male mice for 5 weeks with E(2) or the non-aromatizable androgen dihydrotestosterone (DHT). Both E(2) and DHT increased muscle weight and lean mass, although the effect was less marked after E(2) treatment. Studies of underlying mechanisms were performed using gene transcript profiling (microarray and real-time PCR) in skeletal muscle, and they demonstrated that E(2) regulated 51 genes and DHT regulated 187 genes, with 13 genes (=25% of E(2)-regulated genes) being regulated by both treatments. Both E(2) and DHT altered the expression of Fbxo32, a gene involved in skeletal muscle atrophy, affected the IGF1 system, and regulated genes involved in angiogenesis and the glutathione metabolic process. Only E(2) affected genes that regulate intermediary glucose and lipid metabolism, and only DHT increased the expression of genes involved in synaptic transmission and heme and polyamine biosynthesis. In summary, ER activation by E(2) treatment maintains skeletal muscle mass after orx. This effect is less marked than that of AR activation by DHT treatment, which completely prevented the effect of orx on muscle mass and was partly, but not fully, mediated via alternative pathways.
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