Leptin signaling in the carotid body: mechanisms and consequences

肥胖会导致多种并发症，包括高血压、2型糖尿病和睡眠呼吸障碍 (SDB)，这导致心血管疾病的发病率和死亡率。肥胖及其并发症与 交感神经系统(SNS)活动增加。颈动脉小体(Cb)调节传入信息 SNS和已被确定为潜在的治疗靶点。CB去神经治疗消除了高血压和 高血糖症。强健的CB缺氧性化学反射与呼吸不稳定有关，并增加了 环路增益是SDB的基本特性之一。我们的长期目标是开发新的疗法，这将 通过调节CB活性治疗高血压、糖尿病和肥胖中的SDB。在第一次资助期间 在获奖期间，我们发现了一条独特的途径，脂肪组织产生的激素瘦素通过它在 CB可增加缺氧性化学反射，诱发高血压。瘦素与瘦素的长亚型相互作用 受体，LEPRb，以激活瞬时受体电位黑素7(TRPM7)阳离子通道。 这种机制增加了颈动脉窦神经(CSN)的活性和化学反射，最终导致 空腹血糖、高血压和糖代谢紊乱。我们开发了新的分子方法来 询问针对Leprb基因表达的CB Leptin-TRPM7通路，通过JAK/STAT3和 PI3K与细胞因子信号转导抑制因子SOCS3和蛋白酪氨酸诱导的靶向性瘦素抵抗 磷酸酶1B(PTP1B)。这一提议的首要假设是，在DIO中，瘦素通过 TRPM7在CB-I细胞中增加低氧化学反射和CSN活性导致SNS 激活、高血压、糖尿病和SDB，所有这些都可以用我们新型的TRPM7阻滞剂治疗。 我们将研究瘦素-TRPM7轴在肥胖引起的高血压、糖尿病(特异型)中的作用。 目的1)和SDB(特异性目的2)在饮食诱导肥胖(DIO)小鼠中的作用。我们认为瘦素通过CB发挥作用 TRPM7增加诱发高血压和高血糖的SNS活性并增强化学反射 引起SDB，将通过(A)Leprb shRNA和(B)应用于CB的Trpm7 shRNA来废除；(C)TRPM7 新型缓释制剂给药的阻滞剂FTY720；和(D)LEPRb阻滞剂 CB注射Allo-acA和TRPM7阻滞剂FTY720可降低CSN、膈、内脏和肾脏 交感神经活动。特异靶3将研究LEPRb-TRPM7的细胞和分子调控 DIO小鼠CB中的信号转导。我们认为在DIO中，高水平的瘦素增加了CB球体中TRPM7的活性 细胞(A)急性地通过JAK2/PI3K信号转导；(B)慢性通过增加Leprb和Trpm7基因的表达 JAK2/STAT3途径。我们将使用最先进的技术，包括体内的基因操作 病毒载体在CB中的表达、FTY720水凝胶分子组装、遥测记录、睡眠研究 呼吸定量分析、CB-I型细胞膜片钳和交感神经记录。我们的 翻译提案将确定高血压、糖尿病和肥胖的SDB的潜在新疗法。

Obesity causes multiple complications including hypertension, type 2 diabetes and sleep disordered breathing (SDB), which contribute to cardiovascular morbidity and mortality. Obesity and its complications are linked to increased activity of the sympathetic nervous system (SNS). The carotid bodies (CB) modulate afferent input to the SNS and have been identified as a potential therapeutic target. CB denervation abolished hypertension and hyperglycemia. The robust CB hypoxic chemoreflex has been implicated in respiratory instability and increased loop gain, one of the cardinal traits of SDB. Our long-term goal is to develop novel therapeutics, which will treat hypertension, diabetes and SDB in obesity by modulating the CB activity. During the first funding period of the award, we discovered a unique pathway by which adipose-tissue-produced hormone leptin acts in CB to increase the hypoxic chemoreflex and induce hypertension. Leptin interacts with the long isoform of leptin receptor, LEPRb, on CB type I cells to activate transient receptor potential melastatin 7 (TRPM7) cation channel. This mechanism increases carotid sinus nerve (CSN) activity and the chemoreflex, which ultimately leads to SDB, hypertension and perturbations of glucose metabolism. We developed novel molecular approaches to interrogate the CB leptin-TRPM7 pathway targeting Leprb gene expression, signaling via the JAK/STAT3 and PI3K and targeting leptin resistance induced by suppressor of cytokine signaling-3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B). The overarching hypothesis of this proposal is that, in DIO, leptin acts via TRPM7 in the CB type I cells to increase the hypoxic chemoreflex and CSN activity leading to SNS activation, hypertension, diabetes, and SDB, all of which can be treated by our novel TRPM7 blocker. We will examine the role of the leptin-TRPM7 axis in CB in obesity-induced hypertension, diabetes (Specific Aim 1) and SDB (Specific Aim 2) in mice with diet-induced obesity (DIO). We propose that leptin acts via CB TRPM7 to increase SNS activity inducing hypertension and hyperglycemia and to augment the chemoreflex causing SDB, which will be abolished by (A) Leprb shRNA and (B) Trpm7 shRNA applied to CB; (C) TRPM7 blocker FTY720 in a novel extended release formulation administered to the CB; and that (D) LEPRb blocker Allo-aca and TRPM7 blocker FTY720 administered to CB will decrease CSN, phrenic, splanchnic and renal sympathetic nerve activity. Specific Aim 3 will examine the cellular and molecular regulation of LEPRb-TRPM7 signaling in CB of DIO mice. We propose that in DIO, high leptin levels increase TRPM7 activity in CB glomus cells (A) acutely via JAK2/PI3K signaling; (B) chronically by increasing Leprb and Trpm7 gene expression via the JAK2/STAT3 pathway. We will employ state-of-the-art techniques including in vivo manipulation of gene expression in CB with viral vectors, FTY720 hydrogel molecular assembly, telemetry recording, sleep studies with quantified analysis of breathing, CB type I cell patch clamping and sympathetic nerve recording. Our translational proposal will identify potential novel treatment of hypertension, diabetes and SDB in obesity.