Contribution of the X Chromosome to Sex Differences in Stroke

项目摘要 这项提案的总体目标是确定调控缺血性卒中的性染色体基因 敏感性在老年大脑，并探讨其调节作用的机制。已经 越来越多的人认识到中风是一种性二型疾病，然而， 这些性别差异尚不清楚。老年人占中风患者的大多数， 与同龄男子相比，妇女的发病率、发病率和死亡率较高， 并且这些差异不能仅仅通过暴露于性腺激素来解释。先前的工作已经 显示性染色体补体在老年动物中选择性地导致中风敏感性， 当两性之间的性腺激素相等时。我们已经发现， X染色体剂量（一个X或XX）对小胶质细胞活化和免疫反应的影响。一个突出 衰老X染色体的特征是第二条X染色体上的基因沉默 变得不完整，允许基因逃避X染色体失活（XCI）。这导致 在许多组织中，这些X逃逸基因在XX细胞中的表达高于XY细胞。Kdm 6a和Kdm 5c 是两个X逃逸因子，可以调节干扰素调节因子（IRF）的表达， 负责通过表观遗传修饰激活小胶质细胞。最近的研究发现Kdm 6a和 Kdm 5c在来自老年女性与男性缺血脑的小胶质细胞中更高表达。我们 中心假设是，X染色体补体有助于老年人中风的敏感性 在老年人中，X逃逸基因Kdm 6a和Kdm 5c表观遗传修饰IRF 1/3/4/5/8， 小胶质细胞导致性别特异性炎症反应。在目标1中，我们将使用XY* 鼠标模型来 确定X染色体是否有助于老年动物中风的敏感性。目标2将使用 可诱导的条件性敲除（ICKO）动物模型以检验Kdm 6a和Kdm 5c性别 通过表观遗传修饰的机制，即， H3 K27 me 3和H3 K4 me 3标记的去甲基化。目标3将检验X 染色体和Kdm 6a/Kdm 5c通过介导调节小胶质细胞活化和免疫反应 IRF 1/3/4/5/8的表达。这些拟议的研究将调查Kdm 6a/5c- H3 K27 me 3/H3 K4 me 3-IRFs信号轴，一个非常创新和新颖的领域。我们假设这 在老年人脑卒中发病的性别差异中起着重要作用。

PROJECT SUMMARY The overall goal of this proposal is to determine the sex chromosome genes that regulate ischemic stroke sensitivity in the aged brain, and to explore the mechanisms underlying their regulatory role. It has been increasingly recognized that stroke is a sexually dimorphic disease, however, the mechanisms underlying these sex differences are not known. The elderly constitute the majority of stroke victims, and aged women have a higher incidence, higher morbidity and higher mortality compared to age-matched men, and these differences cannot be explained solely by exposure to gonadal hormones. Previous work has shown the sex chromosome complement contributes to stroke sensitivity selectively in aged animals, when gonadal hormones are equivalent between the sexes. We have found that there is an effect of the X chromosome dosage (one X or XX) on microglial activation and immune responses. A prominent feature of the aged X chromosome is that genetic silencing of genes on the second X chromosome becomes incomplete, allowing for genes to escape from X-chromosome inactivation (XCI). This results in higher expression of these X escapee genes in XX vs. XY cells in many tissues. Kdm6a and Kdm5c are two X escapees that can regulate expression of interferon regulatory factors (IRFs) that are responsible for microglial activation through epigenetic modification. Recent work has found Kdm6a and Kdm5c are more highly expressed in microglia derived from aged female vs. male ischemic brain. Our CENTRAL HYPOTHESIS is that X chromosome complement contributes to stroke sensitivity in the aged brain, AND that the X escapee genes Kdm6a and Kdm5c epigenetically modify IRF1/3/4/5/8 in aged microglia leading to sex-specific inflammatory responses. In Aim 1 we will use the XY* mouse model to determine if the X chromosome contributes to stroke sensitivity in aged animals. Aim 2 will use an inducible conditional knock out (ICKO) animal model to test the hypothesis that Kdm6a and Kdm5c sex specifically impact on stroke outcomes through a mechanism of epigenetic modification, i.e. demethylation of H3K27me3 and H3K4me3 marks respectively. Aim 3 will test the hypothesis that X chromosome and Kdm6a/Kdm5c regulate microglial activation and immune responses through mediation of IRF1/3/4/5/8 expression. These proposed studies will investigate the Kdm6a/5c- H3k27me3/H3K4me3-IRFs signaling axes, a very innovative and novel area. We hypothesize that this pathway plays a critical role in inducing sex differences in stroke in the aged.