Rapid response of cardiac obscurin gene cluster to aortic stenosis: differential activation of Rho-GEF and MLCK and involvement in hypertrophic growth
Rapid response of cardiac obscurin gene cluster to aortic stenosis: differential activation of Rho-GEF and MLCK and involvement in hypertrophic growth
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DOI：
10.1016/j.bbrc.2003.09.035
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发表时间：
2003-10-24
影响因子：
3.1
通讯作者：
Russell, MW
中科院分区：
文献类型：
--
作者：
Borisov, AB;Raekera, MO;Russell, MW
肌球蛋白轻链蛋白激酶(MLCK)是最近发现的两种肌球蛋白轻链蛋白，由同一基因簇编码。这些新基因可能参与了控制心脏适应性和代偿性反应的信号转导级联反应。本研究的目的是研究Darcurin基因簇对小鼠主动脉缩窄引起的心肌肥厚的转录反应。用逆转录酶引发的定量聚合酶链式反应检测黑素基因的转录活性。我们发现，主动脉缩窄后，Oblcurin Rho-Egf和Oblcurin-MLCK内部丝氨酸-苏氨酸激酶II(SK II)结构域的转录显著上调。在肥大生长的不同阶段，含有Rho-gef的转录本的表达水平比对照高2-6倍。在诱导肥大后，SK II基因转录本的数量在24 h和48 h分别增加了10倍和16倍，然后在第7天下降，到第56天恢复到对照水平。编码SK I的羧基末端Oblcurin-MLCK转录本的数量在第2天增加了2倍，并在后期恢复到对照水平。在体外药物诱导的心肌肥大生长过程中，含有Rho-gef结构域的bloscurin在心肌细胞中的免疫定位表明，这种表达与肌原纤维的生长以及肌浆外围肌纤维形成的起始和发展位置有关。这表明在心肌肥厚过程中，暗蛋白合成的上调与额外数量的收缩结构的形成有关。因此，Oblcurin基因簇代表了操纵子的一个新例子，该操纵子编码差异调节的结构和信号蛋白，参与控制正常和肥大生长过程中肌原纤维的组装和适应性重塑。(C)2003 Elsevier Inc.保留所有权利。
Obscurin and obscurin myosin light chain kinase (MLCK) are two recently identified muscle proteins encoded by the same gene cluster. The production of obscurin, which contains a Rho-guanine exchange factor (GEF)-like sequence, and obscurin-MLCK by this cluster suggests that these novel genes may be involved in signal transduction cascades that control adaptive and compensatory responses of the heart. The goal of the present study was to investigate the transcriptional response of the obscurin gene cluster to the initiation of myocardial hypertrophy induced in mice by aortic constriction. The transcriptional activity of the obscurin genes was examined using reverse-transcriptase primed quantitative PCR. We found that the transcripts encoding the obscurin Rho-GEF and the obscurin-MLCK internal serine-threonine kinase II (SK II) domains were significantly upregulated following aortic constriction. The expression of Rho-GEF-containing transcripts at different stages of the hypertrophic growth exceeded the control levels by 2- to 6-fold. Following the induction of hypertrophy, the quantity of the SK II-encoding transcripts increased 10-fold by 24 h and 16-fold by 48 h, then decreased by day 7, and returned to the control level by day 56. The quantity of the carboxy terminal obscurin-MLCK transcripts encoding for SK I increased 2-fold by day 2 and returned to the control values at later stages. Immunolocalization of obscurin, which contains Rho-GEF domain, in cardiomyocytes during pharmacologically induced hypertrophic growth in vitro demonstrated that the expression was topographically associated with the growing myofibrils and with the sites of initiation and progression of myofibrillogenesis at the periphery of the sarcoplasm. This suggests that upregulation of obscurin synthesis is associated with the formation of additional amounts of contractile structures during cardiac hypertrophy. Thus, the obscurin gene cluster represents a new example of an operon that encodes differentially regulated structural and signaling proteins implicated in the control of assembly and adaptive remodeling of myofibrils during normal and hypertrophic growth. (C) 2003 Elsevier Inc. All rights reserved.