Inhibitory cardiac transcription factor, SRF-N, is generated by caspase 3 cleavage in human heart failure and attenuated by ventricular unloading
Inhibitory cardiac transcription factor, SRF-N, is generated by caspase 3 cleavage in human heart failure and attenuated by ventricular unloading
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DOI：
10.1161/01.cir.0000084502.02147.83
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发表时间：
2003-07-29
期刊：
影响因子：
37.8
通讯作者：
Schwartz, RJ
中科院分区：
文献类型：
--
作者：
Chang, J;Wei, L;Schwartz, RJ
背景-关于导致心力衰竭的分子机制的知识仍然有限，但是基因活性降低和半胱天冬酶3的适度激活是终末期心力衰竭的标志。我们推测，血清反应因子（SRF），一个中央心脏转录因子，可能是一个裂解目标为温和的活化半胱天冬酶3，这种裂解的SRF可能发挥主导的抑制作用，在推动心脏走向failure.Methods和结果，我们研究了SRF蛋白水平从心脏移植时采取的13例终末期心力衰竭和7个正常心脏样本。全长SRF显着减少，并加工成55-和32-kDa的亚片段在所有失败的心脏。SRF在正常样本中是完整的。相比之下，10名左心室辅助装置患者的心脏显示出最小的SRF碎片。N-和C-末端SRF序列的特异性抗体和定点突变揭示了2个可供选择的半胱天冬酶3切割位点，因此检测到2个片段，每个片段含有N-或C-末端SRF。SRF-N，32-kDa的片段，在肌原细胞中的表达抑制α-肌动蛋白基因启动子的转录活性的50%至60%，这表明，截短的SRF功能作为一个显性负性transcriptionfactor. Conclusions-Caspase 3激活心力衰竭依次裂解SRF和产生一个显性负性的转录因子，这可以解释抑郁症的心脏特异性基因。此外，半胱天冬酶3的激活可能是可逆的，在衰竭的心脏与心室卸载。
Background-Knowledge about molecular mechanisms leading to heart failure is still limited, but reduced gene activities and modest activation of caspase 3 are hallmarks of end-stage heart failure. We postulated that serum response factor (SRF), a central cardiac transcription factor, might be a cleavage target for modest activated caspase 3, and this cleavage of SRF may play a dominant inhibitory role in propelling hearts toward failure.Methods and Results-We examined SRF protein levels from cardiac samples taken at the time of transplantation in 13 patients with end-stage heart failure and 7 normal hearts. Full-length SRF was markedly reduced and processed into 55- and 32-kDa subfragments in all failing hearts. SRF was intact in normal samples. In contrast, the hearts of 10 patients with left ventricular assist devices showed minimal SRF fragmentation. Specific antibodies to N- and C-terminal SRF sequences and site-directed mutagenesis revealed 2 alternative caspase 3 cleavage sites, so that 2 fragments were detected of each containing either the N- or C-terminal SRF. Expression of SRF-N, the 32-kDa fragment, in myogenic cells inhibited the transcriptional activity of alpha-actin gene promoters by 50% to 60%, which suggests that truncated SRF functioned as a dominant-negative transcription factor.Conclusions-Caspase 3 activation in heart failure sequentially cleaved SRF and generated a dominant-negative transcription factor, which may explain the depression of cardiac-specific genes. Moreover, caspase 3 activation may be reversible in the failing heart with ventricular unloading.