Regulation of IL-6-Type Cytokine Cardioprotective Signaling in the Ischemic Heart

描述（由申请人提供）：转录因子STATS的激活是白细胞介素-6（IL-6）家族细胞因子的定义特征。IL-6和STATS均对心肌细胞具有保护作用，是缺血预处理所必需的。然而，在心肌细胞中调节IL-6细胞因子信号传导的机制在很大程度上未被探索。我们提出，心肌细胞中IL-6细胞因子信号传导的保护特性由3种机制决定：激活STATS的激酶JAK 1的氧化还原调节，S727上STATS的磷酸化，以及终止IL-6细胞因子信号传导的SOCS 3的诱导。此外，我们假设，虽然JAK 1激活和预处理不会发生没有适当的氧化还原状态，不匹配的STATs丝氨酸酪氨酸磷酸化和SOCS 3诱导可能最终证明是有害的。为了研究IL-6家族信号在心肌细胞中的调控机制，我们提出了3个目标。目的1探讨JAK 1氧化还原敏感性在缺血预适应中的作用。我们将评估体内谷胱甘肽耗竭对IL-6家族细胞因子信号传导和预处理的影响。将进行诱变和生化实验以确定JAK 1氧化还原敏感性的机制。我们还将评估体内递送氧化还原不敏感的JAK 1突变体是否增强或恢复预处理保护。目的二是探讨S727磷酸化在预适应和心肌重塑中的作用。我们的工作假设是，S727磷酸化是重要的合作转录，因此哪些基因STATS激活的丝氨酸激酶被激活的影响。我们将通过评估S727磷酸化在预处理诱导的保护性基因表达中的重要性来解决这一假设。我们还将通过微阵列确定哪些STAT诱导的基因不需要S727磷酸化，并确定这些基因是否编码与不良心脏重塑有关的蛋白质。目的3：探讨SOCS 3在缺血预适应中的作用。由于SOCS 3缺陷小鼠在子宫内死亡，我们已经产生了心脏靶向的SOCS 3敲除小鼠。闭胸小鼠心肌缺血-再灌注模型将用于评估SOCS 3缺失对心脏重塑的短期和长期后果。我们认为，了解IL-6细胞因子信号转导是如何调节的，对于开发这些细胞因子的治疗潜力和预适应现象具有重要意义。

DESCRIPTION (provided by applicant): Activation of transcription factor STATS is a defining feature of interleukin-6 (1L-6) family cytokines. Both IL-6 and STATS are protective for cardiomyocytes and necessary for ischemia preconditioning. However, mechanisms regulating IL-6 cytokine signaling in cardiomyocytes are largely unexplored. We propose that the protective character of IL-6 cytokine signaling in cardiomyocytes is determined by 3 mechanisms: redox- regulation of the kinase JAK1 that activates STATS, phosphorylation of STATS on S727, and induction of SOCS3 that terminates IL-6 cytokine signaling. Moreover, we hypothesize that while JAK1 activation and preconditioning will not occur without proper redox status, mismatched STATS serine-tyrosine phosphorylation and SOCS3 induction may ultimately prove detrimental. To investigate regulatory mechanisms of IL-6-family signaling in cardiomyocytes, we propose 3 aims. Aim 1 is to establish the importance of JAK1 redox-sensitivity for ischemic preconditioning. We will assess the impact of glutathione depletion in vivo on IL-6-family cytokine signaling and preconditioning. Mutagenesis and biochemical experiments will be performed to define the mechanism for JAK1 redox-sensitivity. We will also assess if in vivo delivery of a redox-insensitive JAK1 mutant enhances or restores preconditioning protection. Aim 2 is to determine the importance of S727 phosphorylation in preconditioning and cardiac remodeling. Our working hypothesis is that S727 phosphorylation is important for cooperative transcription, and thus which genes STATS activates is affected by which serine kinases are activated. We will address that hypothesis by assessing importance of S727 phosphorylation in preconditioning-induced expression of protective genes. We will also determine by microarray which STATS-induced genes do not require S727 phosphorylation, and establish if those genes encode proteins implicated in adverse cardiac remodeling. Aim 3 is to establish the role of SOCS3 in ischemic preconditioning. Because SOCSS-deficient mice die in utero, we have generated heart-targeted SOCS3 knockout mice. A closed-chest mouse myocardial ischemia-reperfusion model will be used to assess the short- and long-term consequences of SOCS3 deletion on cardiac remodeling. We contend that understanding how IL-6 cytokine signaling is regulated has great significance for exploiting the therapeutic potential of these cytokines and the phenomenon of preconditioning.