DEHYDROEPIANDROSTERONE SULFATE AND INSULIN SECRETION

硫酸脱氢雄甾酮和胰岛素分泌

• 批准号: 6088525
• 负责人: JOSEPH S DILLON
• 金额: $ 21.55万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-15 至 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6088525
• 关键词: RNase protection assay; acyl coA; acyl coA dehydrogenases; cytoplasm; dehydroepiandrosterone; diabetes mellitus; enzyme activity; enzyme inhibitors; fatty acid metabolism; free fatty acids; gene expression; gene targeting; genetically modified animals; glucose metabolism; hormone regulation /control mechanism; insulin; laboratory mouse; lipid metabolism; messenger RNA; pancreatic islets; peroxisome proliferator activated receptor; polymerase chain reaction; receptor expression; secretion; tissue /cell culture

The long-term objective of this research is to develop an understanding of the role of DHEAS in glucose regulation and its potential therapeutic role in diabetes mellitus. Many authors have demonstrated a beneficial effect of DHEA administration in rodent diabetes of various etiologies, however, the mechanism of this effect is unclear. The preliminary studies show that DHEAS strongly enhances the insulinotropic effect of glucose, implicating an effect of DHEAS at the pancreatic beta-cell as a basis for its anti-diabetic effects. Furthermore, the investigators show that DHEAS alters beta-cell expression of specific genes, acyl CoA synthetase-2 (ACS-2) and acyl CoA oxidase (ACO), involved in the intracellular metabolism of fatty acids. Beta cell lipid stores and free fatty acid (FFA) concentrations strongly modulate glucose-stimulated insulin secretion and cytoplasmic long-chain fatty acyl CoA (LC CoA) has been postulated to be an important signal for insulin secretion. It is proposed to test the hypothesis that DHEAS enhances glucose-stimulated insulin secretion by initially stimulating ACS-2 activity, resulting in increased cytoplasmic LC-CoA levels. In addition to enhancing glucose-stimulated insulin secretion, the investigators postulate that the elevated LC-CoA, or a product of LC-CoA, activates beta-cell peroxisome proliferator-activated receptors (PPARs) and consequently increases the activity of the lipid oxidation enzyme ACO. The following Specific Aims will be addressed: (1) Determine whether changing ACS-2 expression alters glucose-stimulated insulin section, ACS activity, cytoplasmic LC-CoA levels, PPARalpha activation and ACO expression, in a similar manner to incubation with DHEAS. Experiments will include assessing: i) the effect of DHEAS on ACS-2 mRNA expression, and ii) the effect of ACS-2 over-expression on glucose-stimulated insulin secretion. (2) Determine whether modulation of LC-CoA levels alters glucose-stimulated insulin secretion, PPARalpha activation or ACO expression. Modulation of LC-CoA levels will be achieved by beta-cell incubation with FFA, etomoxir (an inhibitor of carnitine palmitoyl transferase-1) and Triacsin C (an inhibitor of ACS). (3) Determine whether PPARalpha knockout alters the effect of DHEAS on glucose-stimulated insulin secretion, ACS activity and ACO mRNA expression. (4) Assess the effects of DHEAS on ACS activity, glucose-stimulated insulin secretion and ACO mRNA expression in human pancreatic islets.

这项研究的长期目标是开发一种 了解DHEAS在葡萄糖调节中的作用及其潜力 治疗糖尿病的作用。许多作者已经证明了一个 DHEA给药在各种啮齿动物糖尿病中的有益作用 病因学，然而，这种影响的机制尚不清楚。初步 研究表明DHEAS强烈增强葡萄糖的促胰岛素作用， 暗示DHEAS对胰腺β细胞的作用是其作用的基础。 抗糖尿病作用。此外，研究人员表明DHEAS会改变 β细胞表达特定基因，酰基辅酶A合成酶-2（ACS-2）和酰基辅酶A合成酶-2（ACS-2）。 辅酶A氧化酶（ACO），参与细胞内脂肪酸的代谢。 β细胞脂质储存和游离脂肪酸（FFA）浓度强烈 调节葡萄糖刺激的胰岛素分泌和细胞质长链脂肪酸 酰基辅酶A（LC CoA）被认为是胰岛素的重要信号 分泌物建议检验DHEAS增强 通过最初刺激ACS-2活性来刺激葡萄糖刺激的胰岛素分泌， 导致细胞质LC-CoA水平增加。除了增强 葡萄糖刺激的胰岛素分泌，研究人员假设， 升高的LC-CoA或LC-CoA产物激活β细胞过氧化物酶体 增殖物激活受体（PPARs），从而增加 脂质氧化酶ACO的活性。以下具体目标将 解决：（1）确定ACS-2表达的改变是否改变了 葡萄糖刺激的胰岛素部分，ACS活性，细胞质LC-CoA水平， PPARalpha激活和ACO表达，以与用 DHEAS。实验将包括评估：i）DHEAS对ACS-2 mRNA的影响， 表达，和ii）ACS-2过表达对葡萄糖刺激的 胰岛素分泌(2)确定LC-CoA水平的调节是否改变 葡萄糖刺激的胰岛素分泌、PPARalpha激活或ACO表达。 将通过与FFA孵育β细胞实现LC-CoA水平的调节， etomoxir（肉毒碱棕榈酰转移酶-1抑制剂）和Triacsin C（ ACS抑制剂）。(3)确定PPARalpha敲除是否改变了 DHEAS对葡萄糖刺激的胰岛素分泌、ACS活性和ACO mRNA的影响 表情(4)评估DHEAS对ACS活动的影响，葡萄糖刺激 人胰岛胰岛素分泌和ACO mRNA表达。