钙调神经磷酸酶信号通路与心肌细胞肥大

目的　探讨不同来源的细胞内Ca2 (Ca2 ]i)在钙调神经磷酸酶 (CaN) 活化T细胞核因子 3 (NFAT3 )介导的心肌肥大中的作用。方法　分别用血管紧张素Ⅱ (AngⅡ )或雷尼丁刺激培养的大鼠心肌细胞外Ca2 跨膜内流或细胞内Ca2 释放 ,检测CaN、NFAT3、锌指转录因子 (GATA4)蛋白量、NFAT3定位以及氚 亮氨酸 (3H Leu)掺入量 ,环孢素A作为CaN特异抑制剂。结果　AngⅡ、雷尼丁刺激 1、3d ,心肌细胞CaN、NFAT3、GATA4蛋白表达及3H Leu掺入量较对照组明显增高(P值 <0 0 5或 <0 0 1)。AngⅡ和雷尼丁刺激第 1天 ,心肌细胞NFAT3表达由胞质转入胞核表达为主。环孢素A可抑制上述作用 ,与刺激组相比差异有显著性 (P <0 0 5或 <0 0 1)。结论　刺激心肌细胞Ca2 内流及Ca2 释放 ,均可激活CaN NFAT3信号通路。CaN NFAT3信号通路的激活与Ca2 ]i增加有关 ,而与 Ca2 ]i的来源无关。环孢素A能够抑制AngⅡ和雷尼丁介导的CaN NFAT 3 GATA 4表达的增加和蛋白质合成

CaN-NFAT3 signal pathway: a crucial hinge relates Ca2+ signal with cardiomyocyte hypertrophy

OBJECTIVE: To investigate the role of Ca2+]i from different origins in the course of myocardial hypertrophy mediated by CaN-NFAT3 signal transduction. METHODS: The primarily cultured cardiomyocyte were irritated with angiotensin (Ang) II and ryanodine (RY) which cause Ca2+ inflow and release respectively. Then to observe the changes of CaN-NFAT3 pathway were then observed. Western blotting was employed to semi-quantify CaN, NFAT3 and GATA4. The distribution of NFAT3 was shown with immunocytochemistry, (3)H-Leu incorporation was used as an index of myocyte hypertrophy. Cyclosporin A (CsA) was applied to restrain CaN-NFAT3 pathway as a kind of CaN-selective antagonist. RESULTS: CaN, NFAT3, GATA4 expression significantly increased 1 and 3 days after the stimulation of cardiomyocytes with Ang II and RY (10(-7) mol/L) as compared with that of a control group (P > 0.05) and (3)H-Leu incorporation distinctly increased after Ang II and RY (10(-7) mol/L) stimulation (P > 0.05 versus control group). On the first day of Ang II and RY stimulation, NFAT3 was shown mainly as intra-nuclear expression rather than cytoplasmic expression as seen in the control group. All of the above effects were suppressed by CsA administration, but they were rarely suppressed if CsA was not administered (P > 0.05). CONCLUSIONS: It is shown that both Ca2+ inflow and release may activate CaN-NFAT3 signal pathway, which responds to increase of Ca2+]i and is independent of its origin, indicating the augment of Ca2+]i may trigger CaN-NFAT3 signal transduction and consequently induce myocyte hypertrophy. Moreover, CsA may restrain the expression and activation of CaN-NFAT3 and protein synthesis of myocytes in response to Ang II and RY stimulation.