Epigenetic regulation of myocardial ischemia/reperfusion injury by X chromosome

 描述（由申请人提供）：在所有心血管相关疾病中，冠状动脉疾病仍然是西方国家的主要死亡原因。心脏病的发病率和进展在男性和女性中是不同的，这表明某些保护因素在一种性别中得到增强。该项目的长期目标是确定影响心血管疾病的性染色体和性腺激素调节的细胞和遗传机制，以提高对疾病内源性机制的理解，并确定可能成为治疗目标的性别偏见保护因素。我们实验室以前的研究表明，X染色体的数量导致XX和XY小鼠对心肌缺血/再灌注损伤的反应存在显著差异，与小鼠的性腺性别无关。相对于XY小鼠，XX小鼠显示出对缺血/再灌注（I/R）损伤的显著更大的易感性，以及较低的缺血后心脏收缩功能。XX与XY的差异可归因于X染色体的数量，而不是Y染色体的存在/不存在。Kdm 6a是一种X染色体基因，它能逃脱失活，在XX细胞中的表达高于XY细胞，并且该基因的两个拷贝（如XX细胞中所发生的）比一个拷贝（如XY细胞中所发生的）引起更大的I/R损伤。中心假设是Kdm 6a通过表观遗传调节促进X染色体依赖的me /R损伤。此外，由于雌二醇是一种保护I/R损伤的女性增强因子，一种假设是雌二醇调节KDM 6A的基因靶点。目的1将通过测量具有不同拷贝数的Kdm 6a的小鼠中的梗死面积和心脏功能恢复（从XX小鼠中删除一个拷贝的Kdm 6a，并向XO小鼠添加Kdm 6a）来测试KDM 6A是否负责I/R损伤中的XX与XY差异。目的2寻找组蛋白去甲基化酶KDM 6A的直接作用靶点，并检测KDM 6A剂量对基因表达的影响。这些研究将确定KDM 6A下游基因的短列表，可以测试这些基因以确定它们是否介导KDM 6A对me /R损伤的影响。目的3将比较两个女性特异性因素的影响，卵巢分泌的雌二醇和第二个X染色体的存在，以确定每个因素如何影响另一个因素的影响。将测试由KDM 6A调节的基因，以确定它们是否也受雌二醇调节。这些研究的目的是提供一个更复杂的机械理解的差异，在I/R损伤的女性和男性，着眼于发现新的保护机制，可能成为治疗的目标，在两种性别。

 DESCRIPTION (provided by applicant): Among all cardiovascular-related diseases, coronary artery disease remains the leading cause of death in western countries. The incidence and progression of heart disease is different in males and females, indicating that some protective factors are enhanced in one sex. The long term objectives of this project are to identify cellular and genetic mechanisms, regulated by sex chromosomes and gonadal hormones that affect cardiovascular disease, to improve the understanding of endogenous mechanisms of disease, and to identify sex-biased protective factors that may become targets for therapies. Previous research from our labs indicated that the number of X chromosomes causes striking differences in the response of XX and XY mice to myocardial ischemia/reperfusion injury, independent of the gonadal sex of the mice. XX mice show dramatically greater susceptibility to ischemia/reperfusion (I/R) injury, relative to XY mice, and lower post-ischemic heart contractile function. The XX vs. XY difference is attributable to the number of X chromosomes, not the presence/absence of the Y chromosome. Kdm6a is an X chromosome gene that escapes inactivation and is expressed higher in XX than XY cells, and two copies of this gene (as occurs in XX cells) cause greater I/R injury than one copy (as occurs in XY cells). The central hypothesis is that Kdm6a contributes to X chromosome dependent me /R injury via epigenetic regulation. Moreover, because estradiol is a female-enhanced factor that protects from I/R injury, one hypothesis is that estradiol regulates gene targets of KDM6A. Aim 1 will test whether KDM6A is responsible for the XX vs. XY difference in I/R injury by measuring infarct size and heart functional recovery in mice with different copy numbers of Kdm6a (deleting one copy of Kdm6a from XX mice, and adding Kdm6a to XO mice). Aim 2 will discover direct targets of histone demethylase KDM6A, and measure the changes in expression of genes regulated by KDM6A dosage. These studies will define a short list of genes downstream of KDM6A that can be tested to determine if they mediate KDM6A's effects on me /R injury. Aim 3 will compare the effects of two female-specific factors, estradiol secreted from the ovary, and the presence of a second X chromosome, to establish how each factor influences the effect of the other. Genes regulated by KDM6A will be tested to determine if they are also regulated by estradiol. These studies are intended to provide a more sophisticated mechanistic understanding of the differences in I/R injury in females and males, with an eye towards discovering novel protective mechanisms that could become targets for therapy in both sexes.