Endolysosomal-nuclear communication mediated through V-ATPase and NHE9 dependent epigenetic signaling

肿瘤暴露在不断变化的营养环境中，从而产生新陈代谢压力，从而损害 它们的生长和扩散。因此，癌细胞进化出表型适应来与之抗衡。 需要表观遗传和转录重编程的营养通量。这些表型适应也可以 影响肿瘤细胞对化疗药物的敏感性。细胞质细胞器如何参与营养 信号在核表观基因组上发挥作用仍然是一个需要定义的基本问题，因为 通路是抗癌药物开发的候选治疗靶点。V-ATPase是一种 进化上保守的多聚体质子泵，使内溶酶体隔室酸化以调节 细胞内的pH和激活必需的营养信号通路。Na+/H+交换器(NHE)因子， 具体地说，NHE9拮抗依赖于V-ATPase的内体酸化。NHE9在许多情况下过度表达 肿瘤，最近的研究表明，NHE9在胶质母细胞瘤(GBM)中过表达有助于 直接导致肿瘤的发生。耐人寻味的是，萌芽酵母中的基因筛查发现了V-ATPase和 酵母NHE9同源基因Nhx1通过未知途径调节组蛋白H3和H4(H3/H4)乙酰化 机械装置。我们的初步数据表明，人GBM细胞中的V-ATPase信号也调节 H3/H4乙酰化，从而证明V-ATPase是一个进化保守的表观遗传调节因子。 该项目将检验V-ATPase和Nhx1/NHE9调节内溶酶体的创新假设。 表观遗传适应改变的营养状态所需的核通讯。使用酵母和人类 对于GBM模型，我们将执行以下具体目标。在目标I中，我们将确定关键的营养信号 V-ATPase下游控制全球H3/H4乙酰化的途径，然后我们将确定这是否 涉及对sirtuin脱乙酰酶家族的抑制，或者如果它涉及非sirtuin机制。我们将测试 具体地说，如果依赖V-ATPase的H3/H4乙酰化调节依赖于ATP的染色质的结合 对代谢基因转录很重要的重塑酶。在AIM II中，我们将确定V-ATPase是否 依赖的H3/H4乙酰化控制DNA对烷化剂的损伤反应，包括GBM 标准护理化疗药物替莫唑胺(TMZ)，通过锚定ATP依赖的核小体 将酶重塑为染色质。在项目完成后，我们将通过以下方式定义一个新的范例 内溶酶体间隔调控对代谢基因至关重要的核表观遗传途径 表达和对基因毒性应激的敏感性。

Tumors are exposed to constantly changing nutrient environments which creates metabolic stress that impairs their growth and proliferation. Consequently, cancer cells evolve phenotypic adaptations to contend with this nutrient flux that require epigenetic and transcriptional reprogramming. These phenotypic adaptations also can affect tumor cell sensitivity to chemotherapeutic agents. How cytoplasmic organelles involved in nutrient signaling exert their effects on the nuclear epigenome remains a fundamental problem to define since these pathways are candidate therapeutic targets for anticancer drug development. The V-ATPase is an evolutionarily conserved multimeric proton pump that acidifies the endolysosomal compartment to regulate intracellular pH and activate essential nutrient signaling pathways. Na+/H+ exchanger (NHE) factors, specifically NHE9, antagonize V-ATPase dependent endosomal acidification. NHE9 is overexpressed in many tumors, and recent studies have demonstrated that NHE9 overexpression in glioblastoma (GBM) contributes directly to tumorigenesis. Intriguingly, genetic screens in budding yeast identified both the V-ATPase and the yeast NHE9 ortholog, Nhx1, as regulators of histone H3 and H4 (H3/H4) acetylation through unknown mechanisms. Our preliminary data demonstrate that V-ATPase signaling in human GBM cells also regulates H3/H4 acetylation, thus demonstrating that the V-ATPase is an evolutionarily conserved epigenetic regulator. This project will test the innovative hypothesis that the V-ATPase and Nhx1/NHE9 regulate the endolysosomal- nuclear communication required for epigenetic adaptation to altered nutrient states. Using yeast and human GBM models, we will perform the following Specific Aims. In Aim I, we will identify the key nutrient signaling pathways downstream of the V-ATPase controlling global H3/H4 acetylation, and then we will determine if this involves repression of the sirtuin family of deacetylases or if it involves non-sirtuin mechanisms. We will test specifically if V-ATPase dependent H3/H4 acetylation regulates the binding of ATP-dependent chromatin remodeling enzymes important for transcription of metabolic genes. In Aim II, we will determine if V-ATPase dependent H3/H4 acetylation controls the DNA damage response to alkylating agents, including the GBM standard of care chemotherapeutic agent temozolomide (TMZ), by anchoring ATP-dependent nucleosome remodeling enzymes onto chromatin. Upon the project's completion, we will have defined a novel paradigm by which the endolysosomal compartment regulates nuclear epigenetic pathways critical for metabolic gene expression and sensitivity to genotoxic stress.