| 1. |
- Åberg, N David, 1970, et al.
(författare)
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Insulin-like growth factor-I increases astrocyte intercellular gap junctional communication and connexin43 expression in vitro.
- 2003
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Ingår i: Journal of neuroscience research. - : Wiley. - 0360-4012. ; 74:1, s. 12-22
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Tidskriftsartikel (refereegranskat)abstract
- Connexin43 (cx43) forms gap junctions in astrocytes, and these gap junctions mediate intercellular communication by providing transport of low-molecular-weight metabolites and ions. We have recently shown that systemic growth hormone increases cx43 in the brain. One possibility was that local brain insulin-like growth factor-I (IGF-I) could mediate the effect by acting directly on astrocytes. In the present study, we examined the effects of direct application of recombinant human IGF-I (rhIGF-I) on astrocytes in primary culture concerning cx43 protein expression and gap junctional communication (GJC). After 24 hr of stimulation with rhIGF-I under serum-free conditions, the GJC and cx43 protein were analyzed. Administration of 30 ng/ml rhIGF-I increased the GJC and the abundance of cx43 protein. Cell proliferation of the astrocytes was not significantly increased by rhIGF-I at this concentration. However, a higher concentration of rhIGF-I (150 ng/ml) had no effect on GJC/cx43 but increased cell proliferation. Because of the important modulatory role of IGF binding proteins (IGFBPs) on IGF-I action, we analyzed IGFBPs in conditioned media. In cultures with a low abundance of IGFBPs (especially IGFBP-2), the GJC response to 30 ng/ml rhIGF-I was 81%, compared with the average of 25%. Finally, as a control, insulin was given in equimolar concentrations. However, GJC was not affected, which suggests that rhIGF-I acted via IGF-I receptors. In summary, the data show that rhIGF-I may increase GJC/cx43, whereas a higher concentration of rhIGF-I--at which stimulation of proliferation occurred--did not affect GJC/cx43. Furthermore, IGFBP-2 appeared to modulate the action of rhIGF-I on GJC in astrocytes by a paracrine mechanism.
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| 2. |
- Johnson, Magnus S.C. 1969, et al.
(författare)
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Interaction of scavenger receptor class B type I with peroxisomal targeting receptor Pex5p.
- 2003
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Ingår i: Biochemical and biophysical research communications. - 0006-291X. ; 312:4, s. 1325-34
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Tidskriftsartikel (refereegranskat)abstract
- Scavenger receptor class B type I (SR-BI) is an HDL receptor that mediates selective HDL lipid uptake. Peroxisomes play an important role in lipid metabolism and peroxisomal targeting signal type 1 (PTS1)-containing proteins are translocated to peroxisomes by the peroxisomal targeting import receptor, Pex5p. We have previously identified a PTS1 motif in the intracellular domain of rat SR-BI. Here, we examine the possible interaction between Pex5p and SR-BI. Expression of a Flag-tagged intracellular domain of SR-BI resulted in translocation to the peroxisome as demonstrated by double labeling with anti-Flag IgG and anti-catalase IgG analyzed by confocal microscopy. Immunoprecipitation experiments with anti-SR-BI antibody showed that Pex5p co-precipitated with SR-BI. However, when an antibody against Pex5p was used for immunoprecipitation, only the 57kDa, non-glycosylated form, of SR-BI co-precipitated. We conclude that the PTS1 domain of SR-BI is functional and can mediate peroxisomal interaction via Pex5p, in vitro.
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| 3. |
- Åberg, Maria A I, 1972, et al.
(författare)
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IGF-I has a direct proliferative effect in adult hippocampal progenitor cells.
- 2003
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Ingår i: Molecular and cellular neurosciences. - 1044-7431. ; 24:1, s. 23-40
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to investigate the potential direct effects of insulin-like growth factor-I (IGF-I) on adult rat hippocampal stem/progenitor cells (AHPs). IGF-I-treated cultures showed a dose-dependent increase in thymidine incorporation, total number of cells, and number of cells entering the mitosis phase. Pretreatment with fibroblast growth factor-2 (FGF-2) increased the IGF-I receptor (IGF-IR) expression, and both FGF-2 and IGF-I were required for maximal proliferation. Time-lapse recordings showed that IGF-I at 100 ng/ml decreased differentiation and increased proliferation of single AHPs. Specific inhibition of mitogen-activated protein kinase kinase (MAPKK), phosphatidylinositol 3-kinase (PI3-K), or the downstream effector of the PI3-K pathway, serine/threonine p70 S6 kinase (p70(S6K)), showed that both the MAPK and the PI3-K pathways participate in IGF-I-induced proliferation but that the MAPK activation is obligatory. These results were confirmed with dominant-negative constructs for these pathways. Stimulation of differentiation was found at a low dose (1 ng/ml) of IGF-I, clonal analysis indicating an instructive component of IGF-I signaling.
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| 4. |
- Carlsson, Peter, 1950-, et al.
(författare)
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Optimization of Drying Schedules Adapted for a Mixture of Bords with Distribution of Sapwood and Heartwood
- 2002
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Ingår i: Drying Technology. - 0737-3937 .- 1532-2300. ; 20:2, s. 403-418
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Tidskriftsartikel (refereegranskat)abstract
- A distributed optimization model for wood drying with several different boards simultaneously is presented. Optimization is performed with a gradient-based program. During optimization, convex subproblems are created and transformed to the dual problem and solved. Arbitrary outtakes and board dimensions are possible, as well as different material data and distribution of sapwood and heartwood. It is also possible to optimize drying schedules where drying of boards with variations in environmental conditions is simulated. A two-dimensional orthotropic drying model is used in the moisture transport and structural analysis, where the variation in radial and tangential directions are considered. The influence of temperature and moisture content on material data and mechanical properties is also taken into account. The drying schedules achieved are optimized to minimize drying time for a representative mixture of boards. A numerical example is presented where the drying schedule is optimized for two boards with different outtakes and distributions of sapwood and heartwood. Optimization is performed with two computers in a network. Drying starts from the fibre saturation point in these simulations.
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| 5. |
- Jaskoll, T., et al.
(författare)
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Sonic hedgehog signaling plays an essential role during embryonic salivary gland epithelial branching morphogenesis
- 2004
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Ingår i: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 229:4, s. 722-732
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Tidskriftsartikel (refereegranskat)abstract
- Gene targeting studies indicate that sonic hedgehog (Shh) signaling plays an essential role during craniofacial development. Because numerous mandibular derivatives (e.g., teeth, tongue, Meckel's cartilage) are absent in Shh null mice and the embryonic submandibular salivary gland (SMG) develops from the mandibular arch, we postulated that Shh signaling is important for embryonic SMG development. To address this question, we first determined the spatiotemporal distribution of Shh; two transmembrane proteins, patched 1 (Ptc) and Smoothened (Smo), which act as a negative or a positive regulator of the Shh signal, respectively; and the Gli 3 transcription factor, which is downstream of the Shh signal. The epithelial localization of Shh, Ptc, Smo, and Gli 3 suggests that Shh signaling may act within the epithelium in a juxtacrine manner. The SMG phenotype in our embryonic day (E) 18.5 Shh null mice can be characterized as "paedomorphic," that is, it fails to progress to ontogenic stages beyond the Early Pseudoglandular (similar toE14). In a complementary set of experiments, we used organ culture to evaluate the effect of enhanced or abrogated Shh signaling on embryonic SMG development in vitro. Paired Ell 3 (Late Initial Bud stage) or E14 (Pseudogiandular stage) SMGs were cultured in the presence or absence of exogenous Shh peptide supplementation; Shh-supplemented explants exhibit a significant stage-dependent increase in branching morphogenesis compared with control explants. Furthermore, by using cyclopamine, a steroidal alkaloid that specifically disrupts the Shh pathway, to abrogate endogenous Shh signaling in vitro, we found a significant decrease in branching in cyclopamine-treated explants compared with controls, as well as a significant decrease in epithelial cell proliferation. Our results indicate that Shh signaling plays an essential role during embryonic SMG branching morphogenesis. Exogenous FGF8 peptide supplementation in vitro, rescues the abnormal SMG phenotype seen in cyclopamine-treated explants, demonstrating that overexpression of a parallel, but related, downstream signaling pathway can compensate for diminished Shh signaling and restore embryonic SMG branching morphogenesis. (C) 2004 Wiley-Liss, Inc.
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| 6. |
- Landgren, Henrik, 1978, et al.
(författare)
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FoxJ3, a novel mammalian forkhead gene expressed in neuroectoderm, neural crest, and myotome
- 2004
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Ingår i: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 231:2, s. 396-401
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Tidskriftsartikel (refereegranskat)abstract
- Forkhead transcription factors are important regulators of animal development. Here, we describe the embryonic expression pattern for one of the novel forkhead genes that were discovered as a result of the mouse and human genome projects. It is most closely related to FoxJ2 and has been assigned the name FoxJ3. The 100-kb, 13-exon mouse Foxj3 gene on chromosome 4 encodes a 623 amino acid (aa) protein from an mRNA of at least 4.8 kb (Human FOXJ3: Chr 1, 627 aa, 5.3-kb mRNA). During the stages of mouse development investigated (embryonic day [E] 8.5-E12.5) Foxj3 is expressed in neuroectoderm, in neural crest, and in many structures derived from neural crest cells, such as facioacoustic, trigeminal, and dorsal root ganglia. Stripes of expression appear at E10.5 in the location of myotomes and expand ventrally in a pattern similar to the developing body wall musculature. Developing limbs have a complex pattern of Foxj3 expression that at E12.5 colocalizes with the condensed mesenchyme of the skeletal primordia. (C) 2004 Wiley-Liss, Inc.
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| 7. |
- Lehmann, Ordan J, et al.
(författare)
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Fox's in development and disease.
- 2003
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Ingår i: Trends in genetics : TIG. - 0168-9525. ; 19:6, s. 339-44
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Forskningsöversikt (refereegranskat)abstract
- Since the first forkhead (Fox) gene was identified, the importance of this family of transcription factors has increased steadily with the discoveries of the diverse range of developmental processes that they regulate in eukaryotes. Among other processes, the Fox factors are important in the establishment of the body axis and the development of tissues from all three germ layers. In this article, we present some of the recent data on this gene family with reference to selected phenotypes observed in patients and model organisms, and the sensitivity of developmental processes to alterations in forkhead gene dosage.
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| 8. |
- Lehmann, O. J., et al.
(författare)
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Novel anterior segment phenotypes resulting from forkhead gene alterations: Evidence for cross-species conservation of function
- 2003
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Ingår i: Investigative Ophthalmology & Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 44:6, s. 2627-2633
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE. Mutations in murine and human Versions of an ancestrally related gene usually result in similar phenotypes. However, interspecics differences exist, and in the case of two forkhead transcription factor genes (FOXC1 and FOXC2), these differences include corneal or anterior segment phenotypes, respectively. This study was undertaken to determine whether such discrepancies provide an opportunity for identifying novel human-murine ocular phenotypes. METHODS. Four pedigrees with early-onset glaucoma phenotypes secondary to segmental chromosomal duplications or deletions encompassing FOXC1 and 18 individuals from 9 FOXC2 mutation pedigrees underwent detailed ocular phenotyping. Subsequently, mice with mutations in Foxc1 or a related forkhead gene, Foxe3, were assessed for features of the human phenotypes. RESULTS. A significant increase in central corneal thickness was present in affected individuals from the segmental duplication pedigrees compared with their unaffected relatives (mean increase 13%, maximum 35%, P < 0.05). Alterations in corneal thickness were present in mice heterozygous and homozygous for Foxe3 mutations but neither in Foxc1 heterozygotes nor the small human segmental deletion pedigree. Mutations in FOXC2 resulted in ocular anterior segment anomalies. These were more severe and prevalent with mutations involving the forkhead domain. CONCLUSIONS. Normal corneal development is dependent on the precise dose and levels of activity of certain forkhead transcription factors. The altered corneal thickness attributable to increased forkhead gene dosage is particularly important, because it may affect the clinical management of certain glaucoma subtypes and lead to excessive treatment. The FOXC1 and Foxe3 data, taken together with the novel ocular phenotypes of FOXC2 mutations, highlight the remarkable cross-species conservation of function among forkhead genes.
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| 9. |
- Ormestad, Mattias, 1974, et al.
(författare)
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Differences in the embryonic expression patterns of mouse Foxf1 and -2 match their distinct mutant phenotypes
- 2004
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Ingår i: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 229:2, s. 328-333
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Tidskriftsartikel (refereegranskat)abstract
- Murine genes encoding the forkhead transcription factors Foxf1 and -2 are both expressed in derivatives of the splanchnic mesoderm, i.e., the mesenchyme of organs derived from the primitive gut. In addition, Foxf2 is also expressed in limbs and the central nervous system. Targeted mutagenesis of Foxf1 and -2 suggests that Foxf1 is the more important of the two mammalian FoxF genes with early embryonic lethality of null embryos and a haploinsufficiency phenotype affecting foregut-derived organs. In contrast, the only reported defect in Foxf2 null embryos is cleft palate. To investigate if the differences in mutant phenotype can be attributed to nonoverlapping expression patterns or if distinct functions of the encoded proteins have to be inferred, we analyzed the early embryonic expression of Foxf2 and compared it with that of the better investigated Foxf1. We find that in the early embryo, Foxf1 is completely dominating-in terms of expression-in extraembryonic and lateral plate mesoderm, consistent with the malformations and early lethality of Foxf1 null mutants. Along the developing gut, Foxf1 is highly expressed throughout, whereas Foxf2 expression is concentrated to the posterior part-fitting the foregut haploinsufficiency phenotypes of Foxf1 mutants. Foxf2, on the other hand, is more prominent than Foxf1 in mesenchyme around the oral cavity, as would be predicted from the cleft palate phenotype. The differences in expression pattern also highlight areas where defects should be sought for in the Foxf2 mutant, for example limbs, the posterior gut, genitalia, and derivatives of the neural crest mesenchyme.
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| 10. |
- Rask, Katarina, 1966, et al.
(författare)
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Wnt-signalling pathway in ovarian epithelial tumours: increased expression of beta-catenin and GSK3 beta
- 2003
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 89:7, s. 1298-1304
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Tidskriftsartikel (refereegranskat)abstract
- Beta-catenin is involved in both cell-cell adhesion and in transcriptional regulation by the Wingless/Wnt signalling pathway. Alterations of components of this pathway have been suggested to play a central role in tumorigenesis. The present study investigated, by immunohistochemistry and immunoblotting, the protein expression and localisation of beta-catenin, adenomatous polyposis coli (APC), glycogen synthase kinase 3beta (GSK3beta) and lymphocyte enhancer factor-1 (Lef-1) in normal human ovaries and in epithelial ovarian tumours in vivo and in vitro. Immortalised human ovarian surface epithelium and ovarian cancer cell cells (OVCAR-3) expressed beta-catenin, APC, GSK3beta and Lef-1. Nuclear staining of beta-catenin and Lef-1 were demonstrated only in OVCAR-3 cells. There were significant increases of beta-catenin and GSK3beta, while APC was reduced in ovarian cancer compared to the normal ovary. Beta-catenin and Lef-1 were coimmunoprecipitated in ovarian tumours, but not in the normal ovary. Nuclear localisation of beta-catenin or Lef-1 could not be demonstrated in the normal ovary or in the ovarian tumours. The absence of nuclear localisation of beta-catenin could be due to an increased binding to the cadherin-alpha-catenin cell adhesion complex. In fact, we have earlier reported an increased expression of E-cadherin in ovarian adenocarcinomas. In summary, this study demonstrates an increase in the expression of components of the Wingless/Wnt pathway in malignant ovarian tumours. The increase suggests a role for this signalling pathway in cell transformation and in tumour progression. However, it remains to be demonstrated whether it is an increased participation of beta-catenin in transcriptional regulation, or in the stabilisation of cellular integrity, or both, that is the crucial event in ovarian tumorigenesis.
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