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.

项目摘要/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事件 2型糖尿病（T2DM）中高血糖的发展。最近的证据表明失去 糖尿病中的GSIS与代谢重编程有关，以降低线粒体功能。然而 这些观察结果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 人类β细胞的SLC4A4是在T2DMβ细胞中高度表达的少数独特基因之一 在非糖尿病β细胞中被抑制。 SLC4A4编码Na+-NHCO3-胰腺中的NBCE1B，胰腺和 在控制细胞内pH（PHI）中起关键作用。重要的是，NBCE1的激活增加已经 与增强的细胞内糖酵解和线粒体功能受损相关，表明它可能 有助于GSIS的丧失和随之而来的T2DM发展。初步论文研究支持这一点 假设并证明β细胞中NBCE1b活性的抑制可改善GSIS的体外GSIS并增强 体内葡萄糖耐受性。这些累积观察导致我们发展了博士学位论点 总体目标是表征NBCE1b作为β细胞代谢的新调节剂的作用 T2DM中的功能障碍。彼此之间，特定的目标1（F99）将检验以下假设：T2DM中的β细胞功能障碍 由通过激活NBCE1b激活细胞碱化介导的代谢重编程驱动。给出 NBCE1在维持全身性pH稳态的关键作用，F99独特地定位了我 在K00期间，肾脏中酸碱平衡失调相关的新型机制。 具体而言，NBCE1（NBCE1A）的A-异型成型是HCO3-在 肾。 NBCE1A的缺失与收集管中的代谢性酸中毒和皮质囊肿有关 （光盘）。可溶性腺苷循环（SAC）已被鉴定为CD中的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 信号。有趣的是，CD中的持续营地/PKA激活也已被证明是关键 多囊性肾脏疾病（PKD）中囊肿发育和增殖的介体。因此，主要 我提出的博士后研究方向的目的是表征NBCE1A作为新颖的作用 具体目标2 （k00）将检验以下假设，即NBCE1A介导的HCO3-重吸收会激活可溶性腺苷酸 在收集管道中促进增殖和囊这模型中的循环酶训练酶/PKA信号级联 PKD。 F99和K00在一起将促使我实现我的长期目标，以领导独立 肾脏科研究计划。