Role of protein phosphatase in exocytosis in adrenal chromaffin cells

蛋白磷酸酶在肾上腺嗜铬细胞胞吐作用中的作用

基本信息

批准号：
14570089
负责人：
KIMURA Tomohiko
金额：
$ 2.24万
依托单位：
The Nippon Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Tacrolimus (FK506) and cyclosporin A (CsA) are potent immunosuppressant drugs that have been used in the prophylaxis of allograft rejection in organ transplantation. These compounds inhibit calcineurin, Ca^<2+>/calmodulin-dependent protein phosphatase, thereby resulting in the inhibition of T-lymphocyte activation. Calcineurin is highly conserved and widely distributed in virtually all cell types. Calcineurin has been suggested to regulate the activity of ion channels, neurotransmitter and hormone release. In the present study, the effects of FK506 and CsA on catecholamine (CA) release were examined in cultured bovine adrenal chromaffin cells. The results obtained are as follows.1)In intact cells, FK506 (1-30μM) inhibited CA release stimulated by acetylcholine (ACh ; 100μM), 1,1-dimethyl-4-phenyl-piperadinium iodide (DMPP ; 10μM) or high K^+ (40mM). CsA (1-30μM) had a little inhibitory effect on the ACh- or DMPP-stimulated CA release, whereas it enhanced the high K^+ -stimulated CA release.2)In β-escin-permeabilized cells, FK506 inhibited CA release stimulated by Ca^<2+> (1 and 10μM) in the presence and absence of MgATP (2mM). CsA induced CA release under Ca^<2+> free condition and enhanced the Ca^<2+>-stimulated CA release in the presence and absence of MgATP.It is known that the Ca^<2+>-dependent exocytosis involves at least two distinct steps, ATP-requiring priming stage and ATP-independent fusion step in adrenal chromaffin cells. Therefore, it is suggested that FK506 inhibits the Ca^<2+>-dependent exocytosis probably at the fusion step whereas CsA induces CA release from bovine adrenal chromaffin cells. It is also suggested that their effects on CA release is not related to the inhibitory action of FK506 or CsA on calcineurin.

他克莫司（FK506）和环孢菌素A（CSA）是潜在的免疫抑制药物，在器官移植中的同种异体移植排斥反应中已用于预防。这些化合物抑制钙调蛋白，Ca^<2+>/钙调蛋白依赖性蛋白磷酸酶，从而导致T-淋巴细胞激活的抑制。钙调蛋白是高度保守的，几乎在所有细胞类型中分布。钙调神经酶已被建议调节离子通道，神经递质和雌马释放的活性。在本研究中，在培养的牛肾上腺铬蛋白细胞中检查了FK506和CSA对儿茶酚胺（CA）释放的影响。所获得的结果如下。1）在完整的细胞中，FK506（1-30μM）抑制了乙酰胆碱（ACH;100μM），1,1-二甲基-4-苯基 - 苯基磷脂酰碘化物（DMPP; DMPP;10μm）或高K^+（40mm）刺激的Ca释放。 CSA（1-30μm）对ACH或DMPP刺激的CA释放的抑制作用略有抑制作用，而它增强了在β-埃赛赛 - 渗透性细胞中的高k^+刺激释放。 CSA诱导的CA在CA^<2+>自由状态下释放，并在存在和不存在MGATP的情况下增强了Ca^<2+> - 刺激的CA释放。它众所周知，Ca^<2+> - 依赖性胞吐作用至少涉及至少两个不同的步骤，至少有两个不同的步骤，ATP抗ATP启动阶段启动启动阶段和ATP依赖性型依赖性依赖性型肾上腺肾上腺肾上腺磷酸蛋白细胞。因此，建议FK506抑制Ca^<2+> - 依赖性胞吐作用可能在融合步骤下，而CSA会诱导Ca从牛肾上腺铬脂细胞中释放。还建议它们对CA释放的影响与FK506或CSA对钙调神经酶的抑制作用无关。