Novel Roles of Mitochondrial Angiotensin II in The Proximal Tubule of The Kidney

在美国，每三个成年人中就有一个会患上高血压，需要在#年进行降压治疗。 他们的一生。然而，只有1/2的高血压患者对当前的降压药有反应，1/3的患者有反应。 高血压患者将继续发展为心血管和肾脏并发症。其作用机制 对当前降压治疗反应的潜在控制不良的高血压仍然存在 不完全理解。在NIDDK赠款的支持下，我们已经建立了：1)循环和组织和 Ii由近端小管(PT)通过AT1a受体、内吞受体Megalin或小窝蛋白1-来摄取。 依赖机制：2)内化的Ang II和AT1(AT1a)受体定位于内体和 3)细胞内微量注射Ang II可增加[Ca]i，而暴露于新鲜的 2. 血管紧张素Ⅱ诱导肾皮质核转录转化生长因子-β-1、单核细胞趋化蛋白-1和钠/氢交换器3 (NHE3)通过AT1a受体的反应；4)体外或肾内腺病毒介导的An过表达 血管紧张素Ⅱ与AT1a受体在PT细胞内的融合蛋白诱导NHE3的表达，促进 NA重吸收，并增加血压，以及5)全局或肾脏选择性缺失NHE3可减弱 血管紧张素Ⅱ诱导的高血压。这些研究有力地表明，细胞内Ang II可能在 钠转运在调节PT和血压动态平衡中的作用。在这份A1修订提案中， 我们将检验一个新的假设，即在肾脏的PT中，Ang II和AT1(AT1a)内化到 线粒体，其中mito-Ang II通过激活线粒体对线粒体功能起双重作用 AT1a/Ca~(2+)/NADPH氧化酶/O_2和AT2/eNOS/NO/cGMP信号通路。激活AT1a/ CA2/NADPH氧化酶/O2-途径诱导线粒体呼吸和糖酵解应激，损害 压力排钠反应，升高血压，而线粒体的激活 血管紧张素Ⅱ通过AT2/eNOS/NO/cGMP途径促进血压升高，降低血压。在……里面 目标1，我们将使用高分辨率电子显微镜放射自显影和活体多光子成像来 确定AT1(AT1a)和AT2受体是否定位于甲状旁腺线粒体，以及[125I]- Ang II或Alexa 488®-Ang II内化到小鼠甲状旁腺的线粒体中。在AIM II中，我们将确定 线粒体靶向MITO-Ang II在PT细胞中的过表达是否通过 激活AT1a/Ca~(2+)/NADPH氧化酶/O_2~-信号通路，而MITO-AT2R过表达 通过激活AT2/eNOS/NO/cGMP信号来保护线粒体功能。PT特异性SGLT2启动子 线粒体靶向序列将用于驱动mito-Ang II、mito-AT1aR或 在PT细胞中表达Mito-AT2R。在AIM III中，我们将确定在PT中，mito-Ang II是否激活mito-AT1aR 诱导线粒体呼吸和糖酵解应激，削弱压力钠尿反应，并增加 分别使用特定的PT-AT1a-KO、PT-AT2-KO、PT-NHE3-KO或PT-SIRT3-KO小鼠进行血压测定。

In the United States, one in three adults will develop hypertension and require antihypertensive treatments in their lifetime. Yet only 1/2 of hypertensive patients respond to current antihypertensive drugs, and 1/3 of hypertensive patients will continue to develop cardiovascular and renal complications. The mechanisms underlying poorly controlled hypertension in response to current antihypertensive therapies remain incompletely understood. Supported by NIDDK grants, we have established that: 1) circulating and tissue ANG II is taken up by the proximal tubule (PT) via AT1a receptor-, the endocytic receptor megalin-, or caveolin 1- dependent mechanisms; 2) internalized ANG II and AT1 (AT1a) receptors are localized in the endosomes and nuclei of PT cells; 3) intracellular microinjection of ANG II increases [Ca ]i, whereas exposure of freshly 2+ isolated renal cortical nuclei with ANG II induces transcriptional TGF-β1, MCP-1, and the Na+/H+ exchanger 3 (NHE3) responses via AT1a receptors; 4) in vitro or intrarenal adenovirus-mediated overexpression of an intracellular ANG II fusion protein with AT1a receptors selectively in the PT induces NHE3 expression, promotes Na+ reabsorption, and increases blood pressure, and 5) global- or kidney-selective deletion of NHE3 attenuates ANG II-induced hypertension. These studies strongly suggest that intracellular ANG II may play an important role in the regulation of Na+ transport in the PT and blood pressure homeostasis. In this A1 revised proposal, we will test a new hypothesis that in the PT of the kidney, ANG II and AT1 (AT1a) are internalized into the mitochondria, where mito-ANG II exerts dual roles on the mitochondrial function via activation of the AT1a/Ca2+/NADPH oxidase/O2.- and the AT2/eNOS/NO/cGMP signaling pathways. Activation of the AT1a/ Ca2+/NADPH oxidase/O2.- pathway induces mitochondrial respiratory and glycolysis stress, impairs pressure natriuresis response, and increases blood pressure, whereas activation of the mitochondrial AT2/eNOS/NO/cGMP pathway by ANG II promotes pressure natriuresis and lowers blood pressure. In Aim 1, we will use high resolution electron microscopic autoradiography and intravital multiphoton imaging to determine whether AT1 (AT1a) and AT2 receptors are localized in the mitochondria of the PT, and whether [125I]- ANG II or Alexa 488®-ANG II is internalized into the mitochondria of the PT in mice. In Aim II, we will determine whether overexpression of a mitochondria-targeting mito-ANG II in PT cells impairs mitochondrial function by activating the AT1a/Ca2+/NADPH oxidase/O2.- signaling pathways, whereas overexpression of mito-AT2R protects mitochondrial function by activating the AT2/eNOS/NO/cGMP signaling. The PT-specific sglt2 promoter and the mitochondria-targeting sequence will be used to drive the overexpression of mito-ANG II, mito-AT1aR or mito-AT2R in PT cells. In Aim III, we will determine whether activation of mito-AT1aR by mito-ANG II in the PT induces mitochondrial respiratory and glycolysis stress, impairs pressure natriuresis responses, and increases blood pressure using specific PT-AT1a-KO, PT-AT2-KO, PT-NHE3-KO, or PT-SIRT3-KO mice, respectively.