The ER-mitochondria interface in astrocytes during METH exposure and HIV-1 infection

星形胶质细胞是中枢神经系统健康和神经功能的关键调节因子。星形胶质细胞线粒体功能障碍， 例如由HIV-1和METH引起的，威胁到提供必要的代谢和抗氧化剂支持， 神经元因此，描绘可以靶向防止异常线粒体的调节途径， 星形胶质细胞中的稳态对于确保神经元适应性/存活对抗CNS病理是必要的。 内质网（ER）和线粒体之间的直接接触部位，称为线粒体 相关膜（MAMs）是调节细胞增殖所需的几种细胞过程的中心枢纽。 稳态，包括线粒体代谢活性。事实上，Ca 2+从内质网向线粒体的转移 对线粒体生物能量学至关重要。最近的调查还发现了独特的，但不明确的 三个未折叠蛋白反应（UPR）臂在调节MAM系链和/或信号传导中的贡献。 简单地说，蛋白激酶RNA样内质网激酶（PERK）已被确定为一个关键的调节因子， 对于MAM栓系，肌醇需要激酶1（IRE 1 α）参与调节MAM介导的Ca 2+转移， 转录激活因子6（ATF 6）被怀疑参与MAM的形成，因为已知它介导 ER延长和脂质稳态。然而，这些调控机制尚未完全阐明。 此外，虽然MAM系链和信号传递中的修改已经涉及到许多领域， 在神经退行性病理学中，它们的存在和在星形胶质细胞生物学中的参与仍有待确定。 我们假设内质网-线粒体界面是星形胶质细胞线粒体功能障碍的关键介质 在HIV-1和METH发病过程中通过Ca 2+和非经典UPR信号传导。 拟议的研究将检查星形胶质细胞线粒体功能，UPR诱导，Ca 2 + 信号传导和MAM的形成，以响应METH暴露和HIV-1感染，然后描绘 ER相关机制调节星形胶质细胞线粒体功能，从而代谢和抗氧化 容量目的1将评估METH暴露和HIV-1感染如何改变星形胶质细胞的代谢和抗氧化 容量目的2研究内质网-线粒体界面对HIV-1/MET介导的星形胶质细胞的调控作用 线粒体功能障碍根据我们的初步研究结果，我们建议优先调查以下方面的作用： PERK和IRE 1 α分别在调节MAM束缚和MAM介导的Ca 2+转移中的作用， 功能改变星形胶质细胞线粒体的能力。这些研究将实施药理学抑制剂，具体 沉默（si）RNA和过表达载体以确定UPR诱导、Ca 2+信号传导和MAM如何 在HIV-1/METH发病过程中，系留调节星形胶质细胞线粒体健康。这些发现将有助于 确定介导星形胶质细胞线粒体功能障碍的潜在机制， 有针对性地优化星形胶质细胞和神经元之间的代谢和抗氧化剂偶联，以促进神经元 在神经退行性病变期间存活。

Astrocytes are key regulators of CNS health and neuronal function. Astrocyte mitochondrial dysfunction, such as induced by HIV-1 and METH, threatens the provision of essential metabolic and antioxidant support to neurons. Thus, delineating regulatory pathways that can be targeted to prevent aberrant mitochondria homeostasis in astrocytes will be imperative for ensuring neuronal fitness/survival against CNS pathologies. Direct contact sites between the endoplasmic reticulum (ER) and the mitochondria, termed mitochondrial associated membranes (MAMs), are central hubs for regulating several cellular processes required for homeostasis, including mitochondrial metabolic activity. In fact, the transfer of Ca2+ from the ER to mitochondria is essential for mitochondrial bioenergetics. Recent investigations have also identified unique, yet ill-defined contributions of the three unfolded protein response (UPR) arms in regulating MAM tethering and/or signaling. Briefly, protein kinase RNA-like endoplasmic reticulum kinase (PERK) has been determined as a key regulator for MAM tethering, inositol-requiring kinase 1 (IRE1α) is implicated in regulating MAM-mediated Ca2+ transfer, and activating transcription factor 6 (ATF6) is suspected to participate in MAM formation as it is known to mediate ER elongation and lipid homeostasis. However, these regulatory mechanisms have not yet been fully elucidated. Moreover, while modifications in MAM tethering and signaling have been involved in a number of neurodegenerative pathologies, their presence and participation in astrocyte biology remains to be determined. We hypothesize the ER-mitochondria interface is a key mediator of astrocyte mitochondrial dysfunction via Ca2+ and non-canonical UPR signaling during HIV-1 and METH pathogenesis. The proposed studies will examine changes in astrocyte mitochondrial function, UPR induction, Ca2+ signaling, and MAM formation in response to METH exposure and HIV-1 infection, followed by the delineation of ER-associated mechanisms regulating astrocyte mitochondrial function, and thus metabolic and antioxidant capacity. Aim 1 will evaluate how METH exposure and HIV-1 infection alter astrocyte metabolic and antioxidant capacity. Aim 2 will investigate how the ER-mitochondria interface regulates HIV-1/METH-mediated astrocyte mitochondrial dysfunction. Based on our preliminary findings, we propose to prioritize investigating the roles of PERK and IRE1α in regulating MAM tethering and MAM-mediated Ca2+ transfer, respectively, and how these functions alter astrocyte mitochondrial capacity. These studies will implement pharmacological inhibitors, specific silencing (si)RNAs and overexpression vectors to determine how UPR induction, Ca2+ signaling, and MAM tethering regulate astrocyte mitochondrial health during HIV-1/METH pathogenesis. These findings will help identify underlying mechanisms mediating astrocyte mitochondria dysfunction, which can be therapeutically targeted to optimize the metabolic and antioxidant coupling between astrocytes and neurons to promote neuronal survival during neurodegenerative pathologies.