| 1. |
- Bennet, Hedvig, et al.
(författare)
-
Serotonin (5-HT) receptor 2b activation augments glucose-stimulated insulin secretion in human and mouse islets of Langerhans.
- 2016
-
Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 59:4, s. 744-754
-
Tidskriftsartikel (refereegranskat)abstract
- The Gq-coupled 5-hydroxytryptamine 2B (5-HT2B) receptor is known to regulate the proliferation of islet beta cells during pregnancy. However, the role of serotonin in the control of insulin release is still controversial. The aim of the present study was to explore the role of the 5-HT2B receptor in the regulation of insulin secretion in mouse and human islets, as well as in clonal INS-1(832/13) cells.
|
|
| 2. |
- Christensen, Gitte L., et al.
(författare)
-
Bone morphogenetic protein 4 inhibits insulin secretion from rodent beta cells through regulation of calbindin1 expression and reduced voltage-dependent calcium currents
- 2015
-
Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 58:6, s. 1282-1290
-
Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis Type 2 diabetes is characterised by progressive loss of pancreatic beta cell mass and function. Therefore, it is of therapeutic interest to identify factors with the potential to improve beta cell proliferation and insulin secretion. Bone morphogenetic protein 4 (BMP4) expression is increased in diabetic animals and BMP4 reduces glucose-stimulated insulin secretion (GSIS). Here, we investigate the molecular mechanism behind this inhibition. Methods BMP4-mediated inhibition of GSIS was investigated in detail using single cell electrophysiological measurements and live cell Ca2+ imaging. BMP4-mediated gene expression changes were investigated by microarray profiling, quantitative PCR and western blotting. Results Prolonged exposure to BMP4 reduced GSIS from rodent pancreatic islets. This inhibition was associated with decreased exocytosis due to a reduced Ca2+ current through voltage-dependent Ca2+ channels. To identify proteins involved in the inhibition of GSIS, we investigated global gene expression changes induced by BMP4 in neonatal rat pancreatic islets. Expression of the Ca2+-binding protein calbindin1 was significantly induced by BMP4. Overexpression of calbindin1 in primary islet cells reduced GSIS, and the effect of BMP4 on GSIS was lost in islets from calbindin1 (Calb1) knockout mice. Conclusions/interpretation We found BMP4 treatment to markedly inhibit GSIS from rodent pancreatic islets in a calbindin1-dependent manner. Calbindin1 is suggested to mediate the effect of BMP4 by buffering Ca2+ and decreasing Ca2+ channel activity, resulting in diminished insulin exocytosis. Both BMP4 and calbindin1 are potential pharmacological targets for the treatment of beta cell dysfunction.
|
|
| 3. |
- Edlund, Anna, et al.
(författare)
-
Defective exocytosis and processing of insulin in a cystic fibrosis mouse model
- 2019
-
Ingår i: Journal of Endocrinology. - 1479-6805. ; 241:1, s. 45-57
-
Tidskriftsartikel (refereegranskat)abstract
- Cystic fibrosis-related diabetes (CFRD) is a common complication for patients with cystic fibrosis (CF), a disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). The cause of CFRD is unclear, but a commonly observed reduction in first-phase insulin secretion suggests defects at the beta cell level. Here we aimed to examine beta- and alpha-cell function in the Cftrtm1EUR/F508del mouse model (C57BL/6J), which carries the most common human mutation in CFTR, the F508del mutation. CFTR expression, beta cell mass, insulin granule distribution, hormone secretion and single cell capacitance changes were evaluated using islets (or beta cells) from F508del mice and age-matched wild-type mice aged 7-10 weeks. Granular pH was measured with DND-189 fluorescence. Serum glucose, insulin and glucagon levels were measured in vivo, and glucose tolerance was assessed using IPGTT. We show increased secretion of proinsulin and concomitant reduced secretion of C-peptide in islets from F508del mice compared to WT mice. Exocytosis and number of docked granules was reduced. We confirmed reduced granular pH by CFTR stimulation. We detected decreased pancreatic beta cell area, but unchanged beta cell number. Moreover, the F508del mutation caused failure to suppress glucagon secretion leading to hyperglucagonemia. In conclusion, F508del mice have beta cell defects resulting in 1) reduced number of docked insulin granules and reduced exocytosis, and 2) potential defective proinsulin cleavage and secretion of immature insulin. These observations provide insight into the functional role of CFTR in pancreatic islets and contribute to increased understanding of the pathogenesis of CFRD.
|
|
| 4. |
- Edsfeldt, Andreas, et al.
(författare)
-
Impaired Fibrous Repair: A Possible Contributor to Atherosclerotic Plaque Vulnerability in Patients With Type II Diabetes.
- 2014
-
Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1524-4636. ; 34:9, s. 2143-2150
-
Tidskriftsartikel (refereegranskat)abstract
- Diabetes mellitus (DM) type II is increasing rapidly worldwide. Patients with DM II have a greater atherosclerotic burden and higher risk of developing cardiovascular complications. Inflammation has been proposed as the main cause for the high risk of atherosclerotic disease in DM II. In this study, we compared markers of inflammation and fibrous repair in plaques from subjects with and without DM II.
|
|
| 5. |
- Edsfeldt, Andreas, et al.
(författare)
-
Proinflammatory Role of Sphingolipids and Glycosphingolipids in the Human Atherosclerotic Plaque
- 2016
-
Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1524-4636. ; 36:6, s. 1132-1140
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Lipids are central to the development of atherosclerotic plaques. Specifically, which lipids are culprits remains controversial, and promising targets have failed in clinical studies. Sphingolipids are bioactive lipids present in atherosclerotic plaques, and they have been suggested to have both proatherogenic and antiatherogenic. However, the biological effects of these lipids remain unknown in the human atherosclerotic plaque. The aim of this study was to assess plaque levels of sphingolipids and investigate their potential association with and contribution to plaque vulnerability.APPROACH AND RESULTS: Glucosylceramide, lactosylceramide, ceramide, dihydroceramide, sphingomyelin, and sphingosine-1-phosphate were analyzed in homogenates from 200 human carotid plaques using mass spectrometry. Inflammatory activity was determined by analyzing plaque levels of cytokines and plaque histology. Caspase-3 was analyzed by ELISA technique. Expression of regulatory enzymes was analyzed with RNA sequencing. Human coronary artery smooth muscle cells were used to analyze the potential role of the 6 sphingolipids as inducers of plaque inflammation and cellular apoptosis in vitro. All sphingolipids were increased in plaques associated with symptoms and correlated with inflammatory cytokines. All sphingolipids, except sphingosine-1-phosphate, also correlated with histological markers of plaque instability. Lactosylceramide, ceramide, sphingomyelin, and sphingosine-1-phosphate correlated with caspase-3 activity. In vitro experiments revealed that glucosylceramide, lactosylceramide, and ceramide induced cellular apoptosis. All analyzed sphingolipids induced an inflammatory response in human coronary artery smooth muscle cells.CONCLUSIONS: This study shows for the first time that sphingolipids and particularly glucosylceramide are associated with and are possible inducers of plaque inflammation and instability, pointing to sphingolipid metabolic pathways as possible novel therapeutic targets.
|
|
| 6. |
- Esguerra, Jonathan, et al.
(författare)
-
Regulation of Pancreatic Beta Cell Stimulus-Secretion Coupling by microRNAs.
- 2014
-
Ingår i: Genes. - : MDPI AG. - 2073-4425. ; 5:4, s. 1018-1031
-
Forskningsöversikt (refereegranskat)abstract
- Increased blood glucose after a meal is countered by the subsequent increased release of the hypoglycemic hormone insulin from the pancreatic beta cells. The cascade of molecular events encompassing the initial sensing and transport of glucose into the beta cell, culminating with the exocytosis of the insulin large dense core granules (LDCVs) is termed "stimulus-secretion coupling." Impairment in any of the relevant processes leads to insufficient insulin release, which contributes to the development of type 2 diabetes (T2D). The fate of the beta cell, when exposed to environmental triggers of the disease, is determined by the possibility to adapt to the new situation by regulation of gene expression. As established factors of post-transcriptional regulation, microRNAs (miRNAs) are well-recognized mediators of beta cell plasticity and adaptation. Here, we put focus on the importance of comprehending the transcriptional regulation of miRNAs, and how miRNAs are implicated in stimulus-secretion coupling, specifically those influencing the late stages of insulin secretion. We suggest that efficient beta cell adaptation requires an optimal balance between transcriptional regulation of miRNAs themselves, and miRNA-dependent gene regulation. The increased knowledge of the beta cell transcriptional network inclusive of non-coding RNAs such as miRNAs is essential in identifying novel targets for the treatment of T2D.
|
|
| 7. |
- Fadista, Joao, et al.
(författare)
-
Global genomic and transcriptomic analysis of human pancreatic islets reveals novel genes influencing glucose metabolism.
- 2014
-
Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 111:38, s. 13924-13929
-
Tidskriftsartikel (refereegranskat)abstract
- Genetic variation can modulate gene expression, and thereby phenotypic variation and susceptibility to complex diseases such as type 2 diabetes (T2D). Here we harnessed the potential of DNA and RNA sequencing in human pancreatic islets from 89 deceased donors to identify genes of potential importance in the pathogenesis of T2D. We present a catalog of genetic variants regulating gene expression (eQTL) and exon use (sQTL), including many long noncoding RNAs, which are enriched in known T2D-associated loci. Of 35 eQTL genes, whose expression differed between normoglycemic and hyperglycemic individuals, siRNA of tetraspanin 33 (TSPAN33), 5'-nucleotidase, ecto (NT5E), transmembrane emp24 protein transport domain containing 6 (TMED6), and p21 protein activated kinase 7 (PAK7) in INS1 cells resulted in reduced glucose-stimulated insulin secretion. In addition, we provide a genome-wide catalog of allelic expression imbalance, which is also enriched in known T2D-associated loci. Notably, allelic imbalance in paternally expressed gene 3 (PEG3) was associated with its promoter methylation and T2D status. Finally, RNA editing events were less common in islets than previously suggested in other tissues. Taken together, this study provides new insights into the complexity of gene regulation in human pancreatic islets and better understanding of how genetic variation can influence glucose metabolism.
|
|
| 8. |
|
|
| 9. |
- Hindy, George, et al.
(författare)
-
Several type 2 diabetes-associated variants in genes annotated to WNT signaling interact with dietary fiber in relation to incidence of type 2 diabetes
- 2016
-
Ingår i: Genes & Nutrition. - : Springer Science and Business Media LLC. - 1555-8932 .- 1865-3499. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: TCF7L2 is a central transcription factor in the canonical wingless-type MMTV integration site (WNT) signaling pathway, and genetic variants in TCF7L2 have been found to interact with dietary fiber intake on type 2 diabetes risk. Here, we investigate whether other type 2 diabetes genes could be involved in the WNT signaling pathway and whether variants in such genes might interact with dietary fiber on type 2 diabetes incidence. Results: We included 26,905 individuals without diabetes from the Malmö Diet and Cancer Study cohort. Diet data was collected at baseline using a food frequency questionnaire, a 7-day food record, and an interview. Altogether, 51 gene loci were analyzed for putative links to WNT signaling. Over a mean follow-up period of 14.7 years, 3132 incident cases of type 2 diabetes were recorded. Seven genes (nine single nucleotide polymorphisms (SNPs)) were annotated as involved in WNT signaling including TCF7L2 (rs7903146 and rs12255372), HHEX (rs1111875), HNF1A (rs7957197), NOTCH2 (rs10923931), TLE4 (rs13292136), ZBED3 (rs4457053), and PPARG (rs1801282 and rs13081389). SNPs in TCF7L2, NOTCH2, and ZBED3 showed significant interactions with fiber intake on type 2 diabetes incidence (Pinteraction = 0.034, 0.005, 0.017, and 0.002, respectively). The magnitude of the association between the TCF7L2 risk allele and incident type 2 diabetes increased from the lowest to the highest quintiles of fiber intake. Higher fiber associated with lower type 2 diabetes risk only among risk allele carriers of the NOTCH2 variant and homozygotes of the risk allele of the ZBED3 variant. Conclusions: Our results suggest that several type 2 diabetes susceptibility SNPs in genes involved in WNT signaling may interact with dietary fiber intake on type 2 diabetes incidence.
|
|
| 10. |
- Kjellqvist, Sanela, et al.
(författare)
-
Identification of Shared and Unique Serum Lipid Profiles in Diabetes Mellitus and Myocardial Infarction
- 2016
-
Ingår i: Journal of the American Heart Association. - 2047-9980. ; 5:12
-
Tidskriftsartikel (refereegranskat)abstract
- Background-Diabetes mellitus (DM) and cardiovascular disease are associated with dyslipidemia, but the detailed lipid molecular pattern in both diseases remains unknown. Methods and Results-We used shotgun mass spectrometry to determine serum levels of 255 molecular lipids in 316 controls, 171 DM, and 99 myocardial infarction (MI) events from a cohort derived from the Malmo Diet and Cancer study. Orthogonal projections to latent structures analyses were conducted between the lipids and clinical parameters describing DM or MI. Fatty acid desaturases (FADS) and elongation of very long chain fatty acid protein 5 (ELOVL5) activities were estimated by calculating product to precursor ratios of polyunsaturated fatty acids in complex lipids. FADS genotypes encoding these desaturases were then tested for association with lipid levels and ratios. Differences in the levels of lipids belonging to the phosphatidylcholine and triacylglyceride (TAG) classes contributed the most to separating DM from controls. TAGs also played a dominating role in discriminating MI from controls. Levels of C18:2 fatty acids in complex lipids were lower both in DM and MI versus controls (DM, P=0.004; MI, P=6.0E-06) at least due to an acceleration in the metabolic flux from C18: 2 to C20:4 (eg, increased estimated ELOVL5: DM, P=0.02; MI, P=0.04, and combined elongase-desaturase activities: DM, P=3.0E-06; MI, P=2.0E-06). Minor allele carriers of FADS genotypes were associated with increased levels of C18: 2 (P <= 0.007) and lower desaturase activity (P <= 0.002). Conclusions-We demonstrate a possible relationship between decreased levels of C18: 2 in complex lipids and DM or MI. We thereby highlight the importance of molecular lipids in the pathogenesis of both diseases.
|
|
