NBCe1-mediated Regulation of HCO3- is a Novel Mechanism Underlying Metabolic Reprogramming and Cystogenesis

NBCe1 介导的 HCO3 调节是代谢重编程和细胞发生的新机制

• 批准号: 10555519
• 负责人: Matthew Brown
• 金额: $ 8.71万
• 依托单位: BROAD INSTITUTE, INC.
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-03-30 至 2026-03-29
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10555519
• 关键词: Acid-Base Equilibrium; Adenylate Cyclase; Adult; Apical; Basic Science; Beta Cell; Bicarbonates; Buffers; Cell physiology; Cells; Cellular Metabolic Process; Chemosensitization; Clinical Sciences; Code; Complement 3d Receptors; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyst; Depressed mood; Development; Diabetes Mellitus; Distal; Duct (organ) structure; Environment; Etiology; Event; Excretory function; Failure; Functional disorder; Genes; Glucose; Glycolysis; Goals; Human; Hyperglycemia; Impairment; In Vitro; Inflammation; Insulin; Intercalated Cell; Kidney; Kidney Diseases; Lead; MEKs; Maintenance; Mediating; Mediator of activation protein; Metabolic; Metabolic Pathway; Metabolic acidosis; Metabolism; Mitochondria; Modeling; Mus; Nephrology; Nephrons; Non-Insulin-Dependent Diabetes Mellitus; Output; Pancreas; Pathway interactions; Phase; Play; Polycystic Kidney Diseases; Positioning Attribute; Prevalence; Protein Isoforms; Regulation; Research; Role; Signal Pathway; Signal Transduction; Structure of beta Cell of islet; Testing; Work; combat; diabetic; glucose tolerance; improved; in vivo; in vivo Model; insulin secretion; islet; non-diabetic; novel; novel strategies; pH Homeostasis; preservation; prevent; programs; sensor; solute; therapeutic evaluation; transcriptomics; treatment strategy

PROJECT SUMMARY/ABSTRACT The loss of glucose-stimulated insulin secretion (GSIS) is a critical pathophysiological event precipitating development of hyperglycemia in Type 2 diabetes mellitus (T2DM). Recent evidence suggests that loss of GSIS in diabetes is associated with metabolic reprogramming toward reduced mitochondrial function; however mechanisms underlying these observations remain largely unknown. Recent single cell transcriptomics studies of human β-cells identified SLC4A4 as one of few unique genes highly expressed in T2DM β-cells and repressed in non-diabetic β-cells. Slc4a4 encodes for Na+-nHCO3- cotransporter, NBCe1B in the pancreas and plays a key role in regulating intracellular pH (pHi). Importantly, increased activation of NBCe1 has been associated with enhanced intracellular glycolysis and impaired mitochondrial function suggesting it may contribute to loss of GSIS and consequent development of T2DM. Preliminary dissertation studies support this hypothesis and demonstrate that inhibition of NBCe1B activity in β-cells improves GSIS in vitro and enhances glucose tolerance in vivo. These cumulative observations led us to develop a doctoral dissertation direction with an overall objective to characterize the role of NBCe1B as a novel regulator of β-cell metabolism and dysfunction in T2DM. Accordingly, Specific Aim 1 (F99) will test the hypothesis that β-cell dysfunction in T2DM is driven by metabolic reprogramming mediated by cellular alkalization through activation of NBCe1B. Given the critical role of NBCe1 in maintaining systemic pH homeostasis, the F99 uniquely positions me to elucidate novel mechanisms associated with dysregulation of acid-base balance in the kidney during the K00 phase. Specifically, the A-isoform of NBCe1 (NBCe1A) functions as the key mechanism of HCO3- reabsorption in the kidney. Deletion of NBCe1A is associated with metabolic acidosis and cortical cysts within the collecting duct (CD). Soluble adenylyl cyclase (sAC) has been identified as a HCO3- sensor within the CD. Previous work demonstrated that impaired NBCe1A-mediated HCO3- reabsorption activates sAC-cAMP/PKA mediated signaling. Interestingly, persistent cAMP/PKA activation within the CD has also been demonstrated to be a key mediator of cyst development and proliferation in polycystic kidney disease (PKD). Therefore, the main objective of my proposed postdoctoral research direction is to characterize the role of NBCe1A as a novel regulator of cystogenesis through activation of sAC-cAMP/PKA signaling pathway. Accordingly, Specific Aim 2 (K00) will test the hypothesis that impaired NBCe1A-mediated HCO3- reabsorption activates a soluble adenylyl cyclase-cAMP/PKA signaling cascade in the collecting duct promoting proliferation and cystogenesis in models of PKD. Together, the F99 and K00 will propel me to achieve my long-term goal to lead an independent research program in nephrology.

项目概要/摘要 葡萄糖刺激的胰岛素分泌（GSIS）的丧失是一个关键的病理生理学事件，可导致 2 型糖尿病 (T2DM) 中高血糖的发生。最近的证据表明，失去 糖尿病中的 GSIS 与线粒体功能降低的代谢重编程有关；然而 这些观察结果背后的机制在很大程度上仍然未知。最近的单细胞转录组学研究 的人类 β 细胞确定 SLC4A4 是在 T2DM β 细胞中高度表达的少数独特基因之一，并且 在非糖尿病 β 细胞中受到抑制。 Slc4a4 编码 Na+-nHCO3- 协同转运蛋白、胰腺中的 NBCe1B 在调节细胞内 pH (pHi) 中发挥关键作用。重要的是，NBCe1 的激活增加 与细胞内糖酵解增强和线粒体功能受损有关，表明它可能 导致 GSIS 丧失并随后发展为 T2DM。初步论文研究支持了这一点 假设并证明抑制 β 细胞中 NBCe1B 活性可改善体外 GSIS 并增强 体内葡萄糖耐量。这些累积的观察使我们制定了博士论文方向 总体目标是描述 NBCe1B 作为 β 细胞代谢的新型调节剂的作用， T2DM 功能障碍。因此，特定目标 1 (F99) 将检验 T2DM 中 β 细胞功能障碍的假设 是由通过激活 NBCe1B 的细胞碱化介导的代谢重编程驱动的。给定 NBCe1 在维持全身 pH 稳态中的关键作用，F99 使我能够独特地阐明 与 K00 期肾脏酸碱平衡失调相关的新机制。 具体来说，NBCe1 (NBCe1A) 的 A 亚型是 HCO3- 重吸收的关键机制。 肾。 NBCe1A 缺失与代谢性酸中毒和集合管内皮质囊肿有关 （光盘）。可溶性腺苷酸环化酶 (sAC) 已被确定为 CD 内的 HCO3- 传感器。以前的工作 证明 NBCe1A 介导的 HCO3 重吸收受损会激活 sAC-cAMP/PKA 介导的 发信号。有趣的是，CD 内持续的 cAMP/PKA 激活也被证明是关键 多囊肾病 (PKD) 囊肿发育和增殖的介质。因此，主要 我提出的博士后研究方向的目标是描述 NBCe1A 作为一种新型药物的作用 通过激活 sAC-cAMP/PKA 信号通路调节囊肿发生。因此，具体目标 2 (K00) 将检验以下假设：NBCe1A 介导的 HCO3 重吸收受损会激活可溶性腺苷酸 集合管中的环化酶-cAMP/PKA信号级联促进模型中的增殖和囊肿发生 公钥簿。 F99 和 K00 将共同推动我实现领导独立的长期目标 肾脏病学研究计划。