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- Balhuizen, Alexander, et al.
(författare)
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Activation of G protein-coupled receptor 30 modulates hormone secretion and counteracts cytokine-induced apoptosis in pancreatic islets of female mice.
- 2010
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Ingår i: Molecular and Cellular Endocrinology. - : Elsevier BV. - 1872-8057 .- 0303-7207. ; 320, s. 16-24
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Tidskriftsartikel (refereegranskat)abstract
- The role of the newly discovered estrogen receptor GPR30 in islet physiology and pathophysiology is unclear. We examined GPR30 expression in relation to hormone secretion and possible anti-apoptotic effects in isolated mouse islets using the synthetic GPR30 ligand G-1. The mRNA and protein expression of GPR30 was analyzed by qPCR, Western blot and confocal microscopy. Hormone secretion and cAMP content were determined with RIA and apoptosis in islet cells with the Annexin-V method. GPR30 mRNA and protein expression was markedly higher in islets from females compared to male. This gender difference was not found for the genomic estrogen receptors ERalpha and ERbeta, the ERalpha expression being 10-fold higher than ERbeta in both genders. Confocal microscopy revealed abounden GPR30 expression in insulin, glucagon and somatostatin cells. Dose-response studies of G-1 vs 17beta-estradiol in isolated islets at 1 or 12mM glucose showed an almost identical pattern in that both compounds increased insulin and inhibited glucagon and somatostatin secretion. ICI-182,780 and EM-652, potent antagonists of the 17beta-estradiol receptors (ERalpha and ERbeta) did not influence the amplifying effect of G-1 or 17beta-estradiol on cAMP content or insulin secretion from isolated islets. Cytokine-induced (IL-1beta+TNFalpha+INFgamma) apoptosis in islets, cultured for 24h at 5mM glucose, was almost abolished by G-1 or 17beta-estradiol treatment. Addition of ICI-182,780 or EM-652 did not affect this beneficial effect of G-1 or 17beta-estradiol. Taken together, our findings show that GPR30 is expressed in most islet endocrine cells. The synthetic GPR30 ligand G-1 mimics the non-genomic effects of 17beta-estradiol on islet hormone secretion, cAMP content in islets and its anti-apoptotic effects. G-1 or analogs thereof might be new potential candidates in the therapeutic strategy for type 2 diabetes in women.
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- Kalis, Martins, et al.
(författare)
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α 1-antitrypsin enhances insulin secretion and prevents cytokine-mediated apoptosis in pancreatic β-cells.
- 2010
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Ingår i: Islets. - : Informa UK Limited. - 1938-2022 .- 1938-2014. ; 2:3, s. 185-189
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Tidskriftsartikel (refereegranskat)abstract
- α1-antitrypsin (AAT) is a serine protease inhibitor, which recently has been shown to prevent type 1 diabetes (T1D) development, to prolong islet allograft survival and to inhibit β-cell apoptosis in vivo. It has also been reported that T1D patients have significantly lower plasma concentrations of AAT suggesting the potential role of AAT in the pathogenesis of T1D. We have investigated whether plasma-purified AAT can affect β-cell function in vitro. INS-1E cells or primary rat pancreatic islets were used to study the effect of AAT on insulin secretion after glucose, glucagon-like peptide-1 (GLP-1) and forskolin stimulation and on cytokine-mediated apoptosis. The secreted insulin and total cyclic AMP (cAMP) were determined using radioimmunoassay and apoptosis was evaluated by propidium iodide staining followed by FACS analysis. We found that AAT increases insulin secretion in a glucose-dependent manner, potentiates the effect of GLP-1 and forskolin and neutralizes the inhibitory effect of clonidine on insulin secretion. The effect of AAT on insulin secretion was accompanied by an increase in cAMP levels. In addition, AAT protected INS-1E cells from cytokine-induced apoptosis. Our findings show that AAT stimulates insulin secretion and protects β-cells against cytokine-induced apoptosis, and these effects of AAT seem to be mediated through the cAMP pathway. In view of these novel findings we suggest that AAT may represent a novel anti-inflammatory compound to protect β-cells under the immunological attack in T1D but also therapeutic strategy to potentiate insulin secretion in type 2 diabetes (T2D).
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- Kumar, Rajesh, et al.
(författare)
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Insulinotropic and Antidiabetic Effects of 17{beta}-Estradiol and the GPR30 Agonist G-1 on Human Pancreatic Islets.
- 2011
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Ingår i: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 152:7, s. 2568-2579
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Tidskriftsartikel (refereegranskat)abstract
- We have recently shown that 17β-estradiol (E2) and the synthetic G protein-coupled receptor 30 (GPR30) ligand G-1 have antiapoptotic actions in mouse pancreatic islets, raising the prospect that they might exert beneficial effects also in human islets. The objective of the present study was to identify the expression of GPR30 in human islets and clarify the role of GPR30 in islet hormone secretion and β-cell survival. GPR30 expression was analyzed by confocal microscopy, Western blot, and quantitative PCR in islets from female and male donors. Hormone secretion, phosphatidylinositol hydrolysis, cAMP content, and caspase-3 activity in female islets were determined with conventional methods and apoptosis with the annexin-V method. Confocal microscopy revealed GPR30 expression in islet insulin, glucagon, and somatostatin cells. GPR30 mRNA and protein expression was markedly higher in female vs. male islets. An amplifying effect of G-1 or E2 on cAMP content and insulin secretion from isolated female islets was not influenced by the E2 genomic receptor (ERα and ERβ) antagonists ICI 182,780 and EM-652. Cytokine-induced (IL-1β plus TNFα plus interferon-γ) apoptosis in islets cultured for 24 h at 5 mmol/liter glucose was almost abolished by G-1 or E2 treatment and was not affected by the nuclear estrogen receptor antagonists. Concentration-response studies on female islets from healthy controls and type 2 diabetic subjects showed that both E2 and G-1 displayed important antidiabetic actions by improving glucose-stimulated insulin release while suppressing glucagon and somatostatin secretion. In view of these findings, we propose that small molecules activating GPR30 could be promising in the therapy of diabetes mellitus.
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