MOLECULAR BASIS OF ANTIDIABETOGENIC HORMONE ACTION

抗糖尿病激素作用的分子基础

• 批准号: 2451845
• 负责人: GEORGE G HOLZ
• 金额: $ 18.13万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-05-01 至 1998-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2451845
• 关键词: calcium channel; calcium flux; drug receptors; endocrine pharmacology; glyburide; hormone regulation /control mechanism; incretin hormone; laboratory rat; microspectrophotometry; pancreatic islets; phosphoproteins; voltage /patch clamp

Glucagon-like peptide-1 (GLP-1) is a potent blood glucose-lowering hormone that stimulates the secretion of insulin from pancreatic beta- cells and which is under clinical investigation for use in treatment of non-insulin-dependent diabetes mellitus (NIDDM). This proposal seeks funding to support studies of a newly discovered intracellular Ca2+ signaling system that is activated by GLP-1 in primary culture of rat pancratic beta-cells. Preliminary studies are presented demonstrating that GLP-1 stimulates a large rise of [Ca2+]i that consists of transient and sustained components, and which is triggered by activation of a cAMP-dependent second messenger system. This is noteworthy because a cAMP-mediated rise of [Ca2+]i is known to be a powerful stimulus for secretion of insulin. A first Specific Aim of this proposal is to determine if the transient rise of [Ca2+]i measured in response to GLP-1 results from mobilization of Ca2+ stores as a consequence of protein kinase A-mediated phosphorylation of ryanodine receptor (RYR) intracellular Ca2+ release channels. A second Specific Aim is to determine if the sustained rise of [Ca2+]i results from influx of Ca2+, and if so, to determine what type(s) of ion channels are responsible. Here it is proposed that influx of Ca2+ results from the opening of Ca- NS nonselective cation channels that generate the inward membrane current IcAMP. Surprisingly, these channels open not only in response to GLP-1, but also in response to oral hypoglycemic sulfonylureas such as glyburide that are prescribed for treatment of NIDDM. Therefore, a third Specific Aim is to determine if this action of sulfonylureas is mediated by a high affinity sulfonylurea receptor (SUR) acting as a transmembrane conductance regulator of CA-NS channels. To achieve these Specific Aims, measurements of [Ca2+]i and membrane current will be obtained from rat beta-cells using fura-2 spectrofluorimetry in combination with patch clamp electrophysiology. Our immediate goal is to delineate the signal transduction pathways by which GLP-1 influence intracellular Ca2+ homeostasis in the beta-cell. Our long term goal is to determine if activation of this Ca2+ signaling system explains the therapeutic efficacy of GLP-1 for treatment of NIDDM.

胰高血糖素样肽-1 (GLP-1) 是一种有效的降血糖药物 刺激胰岛β-胰岛素分泌的激素 细胞，目前正在临床研究中用于治疗 非胰岛素依赖型糖尿病（NIDDM）。 该提案寻求 资助新发现的细胞内 Ca2+ 的研究 原代培养大鼠中 GLP-1 激活的信号系统 胰腺β细胞。 初步研究表明 GLP-1 刺激 [Ca2+]i 大幅升高，其中包括短暂的 和持续的组件，并且它是通过激活一个 cAMP 依赖性第二信使系统。 这是值得注意的，因为 众所周知，cAMP 介导的 [Ca2+]i 升高对 胰岛素的分泌。 该提案的第一个具体目标是 确定 [Ca2+]i 的瞬时升高是否响应 GLP-1 由于蛋白质而导致 Ca2+ 储存动员的结果 激酶 A 介导的兰尼碱受体 (RYR) 磷酸化 细胞内Ca2+释放通道。 第二个具体目标是 确定 [Ca2+]i 的持续升高是否是由于 Ca2+ 流入所致， 如果是这样，确定负责的离子通道类型。 这里提出 Ca2+ 的流入是由于 Ca- 的开放造成的。 产生内膜的 NS 非选择性阳离子通道 当前 IcAMP。 令人惊讶的是，这些渠道的开放不仅是为了响应 不仅针对 GLP-1，而且还针对口服降糖磺酰脲类药物的反应 格列本脲，用于治疗 NIDDM。 因此，一个 第三个具体目标是确定磺酰脲类药物的这种作用是否有效 由高亲和力磺酰脲受体 (SUR) 介导 CA-NS 通道的跨膜电导调节剂。 为了实现这些 具体目标是 [Ca2+]i 和膜电流的测量 使用 fura-2 荧光光谱法从大鼠 β 细胞中获得 与膜片钳电生理学相结合。 我们的近期目标是 描绘 GLP-1 影响的信号转导途径 β 细胞中的细胞内 Ca2+ 稳态。 我们的长期目标是 以确定该 Ca2+ 信号系统的激活是否可以解释 GLP-1治疗NIDDM的疗效。