Repression of the cardiac myosin light chain-2 gene in skeletal muscle requires site-specific association of antithetic regulator, Nished, and HDACs.
Repression of the cardiac myosin light chain-2 gene in skeletal muscle requires site-specific association of antithetic regulator, Nished, and HDACs.
复制标题
骨骼肌中心肌肌球蛋白轻链 2 基因的抑制需要对立调节因子、Nished 和 HDAC 的位点特异性关联。
DOI：
10.1111/j.1582-4934.2008.00525.x
复制
发表时间：
2009
影响因子：
5.3
通讯作者：
Siddiqui,MAQ
中科院分区：
文献类型：
--
作者：
Mathew,Sumy;Galatioto,Josephine;Mascareno,Eduardo;Siddiqui,MAQ
调控心肌基因组织特异性表达的转录激活机制已被广泛研究，但对非心脏细胞中抑制心脏特异性基因的调控事件知之甚少。我们之前报道过，在肌球蛋白轻链2 （MLC2v）基因中，一种普遍存在的转录因子nied与一个正序列元件内含子调控元件（IRE）以及一个负作用元件心脏特异性序列（CSS）相互作用，分别促进心脏和骨骼肌细胞中该基因的激活和抑制。本研究表明，骨骼肌细胞中心肌MLC2v基因的负调控是通过与组蛋白去乙酰化酶（HDAC）协同抑制因子的相互作用介导的。用HDAC抑制剂Trichostatin A （TSA）处理细胞，以剂量依赖的方式减轻了nishar的抑制活性。在培养的原代肌细胞和表达稳定的骨骼肌细胞系中进行的共转染研究表明，当其仅与CSS相关时，finished下调心肌MLC2基因的表达。染色质免疫沉淀数据表明，CSS介导的骨骼肌细胞心肌MLC2v基因的抑制排除了阳性元素IRE的参与，尽管存在相同的完成结合位点。综上所述，MLC2v转录的负调控似乎基于双重调控模式，一是使IRE无法进入；二是促进在抑制性CSS位点形成转录抑制复合体以沉默骨骼肌细胞中的心脏基因。
The transcriptional activation mechanisms that regulate tissue‐specific expression of cardiac muscle genes have been extensively investigated, but little is known of the regulatory events involved in repression of cardiac‐specific genes in non‐cardiac cells. We have previously reported that Nished, a ubiquitous transcription factor, interacts with a positive sequence element, the Intron Regulatory Element (IRE) as well as a negatively acting element, the Cardiac‐Specific Sequence (CSS), in myosin light chain‐2 (MLC2v) gene to promote activation and repression of the gene in cardiac and skeletal muscle cells respectively. Here, we show that the negative regulation of cardiac MLC2v gene in skeletal muscle cells is mediatedviathe interaction of Nished with histone deacetylase (HDAC) co‐repressor. Treatment of cells with the HDAC inhibitor, Trichostatin A (TSA), alleviates the repressor activity of Nished in a dose‐dependent manner. Co‐transfection studies in primary muscle cells in culture and in Nished expressing stable skeletal muscle cell line demonstrate that Nished down‐regulates the cardiac MLC2 gene expression when its association is restricted to CSS alone. Chromatin immunoprecipitation data suggest that the CSS‐mediated repression of cardiac MLC2v gene in skeletal muscle cells excludes the participation of the positive element IRE despite the presence of an identical Nished binding site. Taken together, it appears that the negative control of MLC2v transcription is based on a dual mode of regulations, one that affords inaccessibility of IRE to Nished and second that promotes the formation of the transcription repression complex at the inhibitory CSS site to silence the cardiac gene in skeletal muscle cell.