Role of the Androgen Receptor in Insulin Secretion in the Male

这项更新申请的目的是进一步阐明睾酮对人外周血淋巴细胞的作用机制。 雄激素受体（AR）在男性胰岛素分泌胰腺β细胞增强胰岛素分泌，通过放大 胰高血糖素样肽-1（GLP-1）的作用。睾酮缺乏在胰腺β细胞病变中的作用 男性中易患2型糖尿病（T2 D）的功能障碍的研究很少。虽然已经确定， 睾酮的作用是通过AR介导的，AR是一种配体激活的转录因子，AR在β-细胞中的作用是 功能仍然知之甚少。由这次优异奖I 01 BX 003725资助，新的和最近出版的 我们实验室研究AR在β细胞功能中的作用的深远的初步数据提供了 以下信息：1）β细胞中AR条件性缺失（βARKO）的雄性小鼠表现出降低的 葡萄糖刺激的胰岛素分泌（GSIS）和发展β细胞无法产生足够的胰岛素，导致 T2 D; 2）AR的促胰岛素功能在来自具有T2 D的男性人类供体的胰岛中重现， 将循环睾酮转化为有效AR激动剂二氢睾酮（DHT）的酶机制; 3)DHT激活小鼠和人类β细胞中的一种胞核AR，通过扩增GSIS来增强GSIS。 胰高血糖素样肽-1（GLP-1）对GLP-1受体的作用，增加血浆中cAMP的产生 4）DHT选择性地增强GLP-1介导的cAMP产生和GSIS，但不 葡萄糖-促胰岛素多肽（GIP）或胰高血糖素（GCN）的扩增; 5）来自胰岛的GSIS的DHT扩增 需要酪氨酸激酶SRC，即雷帕霉素复合物2的哺乳动物靶蛋白（mTORC 2）， 跨膜（tmAC）和可溶性（sAC）腺苷酸环化酶。根据这些广泛的初步数据， 在申请中提出的先前研究的科学严谨性，我们的首要假设是，在男性中， β细胞，DHT作用于质膜附近的AR，结合SRC和磷酸肌醇3-激酶 （PI 3 K），从而募集mTORC 2并增加质膜上tmAC和sAC的活性， 核内体这增强了cAMP和GSIS的GLP-1受体（GLP-1 R）产生。DHT激活的AR是 选择性偏向GLP-1 R，因为AR和GLP-1 R独特地会聚于mTORC 2信号传导， 激活tmAC和sAC以在相似的微区中产生cAMP。这项工作利用基因， 在转基因小鼠以及人类胰岛和β细胞中的生理学和药理学工具。 这项工作是特别相关的对老化和雄激素缺乏的男性退伍军人和T2 D 流行病，因为AR是一个很好的药物靶点。本申请中提出的工作目标 目的是阐明DHT激活的AR刺激cAMP产生并增强cAMP生成的分子基础。 GLP-1在质膜和核内体上发出信号，增加男性的胰岛素分泌。因此，委员会认为， 本申请的具体目的是：1）检验人β细胞中的AR激活增强了 与SRC对接后的GLP-1促胰岛素作用、mTORC 2的募集和tmAC的激活， sAC，其增加质膜和核内体处的cAMP产生; 2）揭示新的雄激素 通过绘制人β细胞中AR相互作用组和功能信号网络对胰岛素分泌的作用; 3)用雄激素在小鼠体内翻译雄激素刺激胰岛素分泌的结果 选择性激活AR膜/细胞核作用的树枝状聚合物缀合物。拟议的工作将填补 我们对b细胞功能的基本机制的理解存在关键差距， 科学的影响和开放的临床相关途径雄激素缺乏男性退伍军人糖尿病。

The goal of this renewal application is to further elucidate the mechanisms by which testosterone action on the androgen receptor (AR) in male insulin-producing pancreatic β-cells enhances insulin secretion by amplifying glucagon-like peptide-1 (GLP-1) actions. The role of testosterone deficiency as a cause of pancreatic β–cell dysfunction predisposing to type 2 diabetes (T2D) in men is poorly studied. While it is established that testosterone action is mediated via the AR, a ligand-activated transcription factor, the role of the AR in β-cell function is still poorly understood. Funded by this Merit Award I01BX003725, the new and recently published far-reaching preliminary data from our laboratory investigating the role of the AR in β-cell function provides the following information: 1) male mice with conditional deletion of the AR in β-cells (βARKO) exhibit decreased glucose-stimulated insulin secretion (GSIS) and develop β-cell failure to produce enough insulin, leading to T2D; 2) the insulinotropic function of AR is recapitulated in islets from male human donors that have the enzymatic machinery to convert circulating testosterone to the potent AR agonist dihydrotestosterone (DHT); 3) DHT activates an extranuclear AR in mouse and human β-cells that enhances GSIS by amplifying the actions of glucagon-like peptide-1 (GLP-1) on the GLP-1 receptor, increasing cAMP production at the plasma membrane and endosomes; 4) DHT selectively enhances GLP-1-mediated cAMP production and GSIS but not that of glucose-insulinotropic polypeptide (GIP) or glucagon (GCN); 5) DHT amplification of GSIS from islets requires the tyrosine kinase SRC, the mammalian target of rapamycin complex 2 (mTORC2), and the activities of transmembrane (tmAC) and soluble (sAC) adenylate cyclases. Based on this extensive preliminary data and the scientific rigor of previous research presented in the application, our overarching hypothesis is that in male β-cells, DHT action on AR in the vicinity of the plasma membrane binds SRC and phosphoinositide 3-kinase (PI3K), thus recruiting mTORC2 and increasing the activities of tmAC and sAC at the plasma membrane and endosomes. This enhances GLP-1 receptor (GLP-1R) production of cAMP and GSIS. DHT-activated AR is selectively biased toward the GLP-1R, because AR and GLP-1R uniquely converge on mTORC2 signaling to activate tmAC and sAC to produce cAMP in similar microdomains. The proposed work uses genetic, physiological and pharmacological tools in genetically modified mice, as well as in human islets and β-cells. This work is particularly relevant against to the aging and androgen-deficient male Veterans and the T2D epidemic, because the AR is a well-characterized drug target. The goal of the work proposed in this application is to elucidate the molecular bases by which DHT-activated AR stimulates cAMP production and enhances GLP-1 signaling at the plasma membrane and endosomes to increase insulin secretion in males. Accordingly, the specific aims of this application are to 1) Test the hypothesis that AR activation in human β cells enhances GLP-1 insulinotropic action following docking to SRC, recruitment of mTORC2, and activation of tmAC and sAC, which increases cAMP production at the plasma membrane and endosomes; 2) Unmask novel androgen actions on insulin secretion by mapping the AR interactome and functional signaling network in human β cells; 3) Translate the findings of androgen stimulation of insulin secretion in vivo in mice using an androgen dendrimer conjugate that selectively activates AR membrane/extranuclear actions. The proposed work will fill key gaps in our understanding of the fundamental mechanisms of b-cell function and will have a lasting scientific impact and open clinically relevant avenues for androgen-deficient male Veterans with diabetes.