血管紧张素Ⅱ和血小板源生长因子对心肌细胞周期素和p27蛋白表达量的调节

Angiotensin Ⅱ and platelet derived growth factor regulate the expression of cyclins and cyclin dependent kinase inhibitor p27 in cardiac myocytes

目的：细胞周期素（ｃｙｃｌｉｎ）和ＣＤＫ抑制蛋白（ＣＫＩ）是对细胞周期起正性和负性调节作用的两类物质。ｐ２７蛋白是ＣＫＩ的一种，主要对细胞外部促进或抑制增殖的信号起反应。本文观察血管紧张素Ⅱ（ＡｎｇⅡ）和血小板源生长因子（ＰＤＧＦ）对心肌细胞细胞周期素和ｐ２７蛋白表达量的影响。方法：培养的心肌细胞除血清２４ｈ使其处于静止状态，加入ＡｎｇⅡ１０－６ｍｏｌ／Ｌ、ＰＤＧＦ－ＢＢ２０ｎｇ／ｍＬ后不同时间收集细胞，用碘化丙啶（ＰＩ）标记细胞ＤＮＡ，以确定细胞所处的周期。用细胞周期素或ｐ２７蛋白的单抗和标记ＦＩＴＣ的二抗标记细胞，用流式细胞仪测定被激发出的荧光量来测定细胞周期素和ｐ２７蛋白表达的相对量。结果：ＡｎｇⅡ可促进细胞周期素的表达，但对ｐ２７蛋白的表达没有影响，不能促进心肌细胞增殖；ＰＤＧＦ明显促进心肌细胞细胞周期素的表达，也不能明显抑制ｐ２７的表达，也不能促进心肌细胞增殖。结论：细胞周期素的表达增加与心肌细胞能否进入细胞周期并不一致，ｐ２７蛋白是心肌细胞能否进入细胞周期并进行有丝分裂的重要调节因子。

AIM: To investigate cell cycle distribution of cardiac myocytes(CM) and expression of cyclins and p27 (one of cyclin dependent kinase inhibitors) caused by angiotensin Ⅱ(AngⅡ) and platelet derived growth factor BB(PDGF-BB). METHODS: Cultured CMs were deprived of fetal calf serum for 24 hours to make quiescent. CMs were collected at different times after stimulation of AngⅡand PDGF-BB. Cell cycle distribution and expression of cyclins and p27 were determined with flow cytometer. RESULTS: AngⅡincreased expression of cyclins, but had no effects on expression of p27. PDGF could enhanced expression of cyclins significantly, but did not inhibit p27 expression. Both could not promote CM proliferation. CONCLUSION: Enhanced expression of cyclins was not correlated to progression of CM cell cycle. p27 inhibits CM progression through G 1 to S phase and thus inhibited CM proliferation.