Role of H11 kinase in cardiac cell growth

描述（由申请人提供）：H11激酶是ICP10蛋白激酶的真核同源物，ICP10蛋白激酶是来自单纯疱疹病毒生长所需的Ras-GAP激酶。在正常组织中，H11激酶的表达仅限于心脏和骨骼肌。虽然其功能尚不清楚，但H11激酶可能参与细胞生长机制，因为它在非肌肉细胞中的诱导促进了向癌细胞的转化。推测的相互作用包括核酪蛋白激酶II (NUCKS II)，一种细胞生长的刺激物，蛋白HSP27，一种细胞存活的刺激物，以及核小体组装蛋白1 (nap -1)，一种细胞增殖的刺激物。通过减法杂交，我们意外地发现H11激酶转录物和蛋白在可逆性缺血/再灌注和慢性左心室肥厚的大型哺乳动物模型中上调。我们的初步数据表明，在分离的心肌细胞中，H11激酶的过表达促进了细胞的生长。已经产生了心脏特异性转基因小鼠，证实了H11激酶的过表达可诱导心肌肥大，并在体内保护缺血/再灌注过程中的细胞死亡。基于这些观察结果，本研究的总体目标是确定H11激酶在心肌中的生理作用、信号机制和功能重要性。第一个具体目的是在心脏特异性转基因小鼠模型中确定H11激酶过表达的体内功能和基因组效应，该模型呈主动脉横带或缺血/再灌注。我们假设转基因小鼠的H11激酶过表达会减少肥壮和缺血心脏的不可逆细胞损伤。第二个目的是确定H11激酶整合的信号通路。我们假设H11激酶通过刺激NUCKS II、HSP27和nap - 1来促进心脏生长和存活，但其他意想不到的蛋白也可能相互作用。第三个目的是在体外显性阴性和体内敲除模型中证明H11激酶是心脏生长和存活的重要途径。我们假设H11激酶的组织限制性表达是一个特定的信号通路的基础，这对于正常的心脏细胞生长是不可缺少的。这些实验将揭示心脏生长的新机制和信号通路，这可能为缺血性心脏病和心力衰竭提供新的治疗途径。

DESCRIPTION (provided by applicant): H11 kinase is the eukaryotic homologue of ICP10 protein kinase, a Ras-GAP kinase from Herpes Simplex required for virus growth. In normal tissues, H11 kinase expression is restricted to the heart and skeletal muscle. Although its function remains unknown, H11 kinase probably participates in mechanisms of cell growth because its induction in non-muscular cells promotes transformation into cancer cells. Putative interactions include the nuclear casein kinase II (NUCKS II), a stimulator of cell growth, the protein HSP27, a stimulator of cell survival, and the nucleosome assembly protein-1 (NAP-l), a stimulator of cell proliferation. By subtractive hybridization, we unexpectedly found that H11 kinase transcript and protein are upregulated in large mammalian models of reversible ischemia/reperfusion and chronic left ventricular hypertrophy. Our preliminary data show that overexpression of H11 kinase in isolated cardiac myocytes promotes cell growth. A cardiac-specific transgenic mouse has been generated, which confirms that overexpression of H11 kinase induces cardiac hypertrophy and protects against cell death during ischemia/reperfusion in vivo. Based on these observations, the overall goal of this proposal is to determine the physiological role, signaling mechanisms and functional importance of H11 kinase in the myocardium. The first specific aim is to determine in vivo the functional and genomic effects of H11 kinase overexpression in a cardiac-specific transgenic mouse model submitted to transverse aortic banding or ischemia/reperfusion. We hypothesize that H11 kinase overexpression in transgenic mice will decrease irreversible cellular damage in hypertrophied and ischemic hearts. The second aim is to determine the signaling pathways in which H11 kinase is integrated. We hypothesize that H11 kinase promotes cardiac growth and survival by stimulating NUCKS II, HSP27 and NAP-l, but that other unexpected proteins might interact as well. The third aim is to show, both in vitro with a dominant negative and in vivo in a knock-out model, that H11 kinase represents an essential pathway of cardiac growth and survival. We hypothesize that the tissue-restricted expression of H11 kinase underlies a specific signaling pathway that is not dispensable for normal cardiac cell growth. These experiments will unravel novel mechanisms and signaling pathways of cardiac growth, which may result in new therapeutic avenues for both ischemic heart disease and heart failure.