MASS SPECTROMETRIC EVIDENCE AGENTS WHICH CAUSE CA2+ LOSS

导致 CA2 丢失的质谱证据

• 批准号: 6665870
• 负责人: WILLIAM NOWATZKE
• 金额: $ 15.75万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2003-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6665870
• 关键词: biomedical resource; child (0-11); female; male; musculoskeletal system; nutrition; nutrition related tag; proteins; spectrometry

Stimulation of pancreatic islets with glucose induces phospholipid hydrolysis and accumulation of nonesterified arachidonic acid, which may amplify the glucose-induced Ca2+ entry into islet ?-cells that triggers insulin secretion. Ca2+ loss from ?-cell intracellular compartments has been proposed to induce both Ca2+ entry and events dependent on arachidonate metabolism. We examine here effects of inducing Ca2+ loss from intracellular sequestration sites with ionophore A23187 and thapsigargin on arachidonate hydrolysis from islet phospholipids. A23187 induces a decline in islet arachidonate-containing phospholipids and release of nonesterified arachidonate. A23187-induced arachidonate release is of similar magnitude when islets are stimulated in Ca2+-replete or in Ca2+-free media or when islets loaded with the intracellular Ca2+ chelator BAPTA are stimulated in Ca2+-free medium, a condition in which A23187 induces no rise in ?-cell cytosolic [Ca2+]. Thapsigargin also induces i sletarachidonate release under these conditions. A23187-or thapsigargin-induced arachidonate release is prevented by a bromoenol lactone (BEL) inhibitor of a ?-cell phospholipase A2 (iPLA2) which does not require Ca2+ for catalytic activity and which is negatively modulated by and physically interacts with calmodulin by Ca2+-dependent mechanisms. Agents which cause Ca2+ loss from islet intracellular compartments thus induce arachidonate hydrolysis from phospholipids by a BEL-sensitive mechanism that does not require a rise in cytosolic [Ca2+], and a BEL-sensitive enzyme like iPLA2 or a related membranous activity may participate in sensing Ca2+ compartment content.

用葡萄糖刺激胰岛诱导磷脂产生 非酯化花生四烯酸的水解和积累， 可能会放大葡萄糖诱导的 Ca2+ 进入胰岛 β 细胞， 触发胰岛素分泌。 α-细胞胞内 Ca2+ 损失 已提出隔室可诱导 Ca2+ 进入和事件 依赖于花生四烯酸代谢。 我们在这里检查的影响 诱导细胞内隔离位点 Ca2+ 损失 离子载体 A23187 和毒胡萝卜素对花生四烯酸水解的影响 胰岛磷脂。 A23187 诱导胰岛减少 含花生四烯酸的磷脂和非酯化的释放 花生四烯酸。 A23187 诱导的花生四烯酸释放具有相似的 当胰岛在充满 Ca2+ 或无 Ca2+ 的情况下受到刺激时的幅度 培养基或当胰岛负载细胞内 Ca2+ 螯合剂 BAPTA 时 在不含 Ca2+ 的培养基中受到刺激，在这种情况下 A23187 不诱导 β 细胞胞质 [Ca2+] 升高。 毒胡萝卜素也 在这些条件下诱导 sletarachidonate 释放。 A23187-或 溴烯醇可阻止毒胡萝卜素诱导的花生四烯酸释放 β-细胞磷脂酶 A2 (iPLA2) 的内酯 (BEL) 抑制剂， 不需要Ca2+来发挥催化活性，这是负面的 受钙调蛋白调节并与钙调蛋白发生物理相互作用 Ca2+ 依赖性机制。 导致胰岛 Ca2+ 损失的药物 细胞内区室因此诱导花生四烯酸水解 磷脂通过 BEL 敏感机制，不需要 胞质 [Ca2+] 升高，以及 BEL 敏感酶（如 iPLA2 或 相关的膜活性可能参与感知 Ca2+ 隔间内容。