Specifying Control Over Ion Balance and Glucose Homeostasis Through mTORC2

描述（由申请人提供）：本研究提案的总体目标是使用生物化学、电生理学、代谢、遗传和整体动物生理学技术，进一步阐明mTORC 2靶点特异性的分子机制及其在葡萄糖稳态和离子平衡调节中的功能意义。K01辅导职业发展奖的申请人凯瑟琳·E·格里森目前是加州大学旧金山分校大卫皮尔斯博士实验室的博士后研究员。格里森博士的长期研究目标是研究代谢信号通路如何交叉和影响控制各种生物功能的通路，特别是肾脏的离子平衡，以维持生理稳态。格里森博士的长期职业目标是建立一个独立的分子生理学研究计划，作为学术机构的终身研究员。SGK1和Akt是高度相关的蛋白激酶，分别作为控制离子和代谢稳态的信号传导途径的关键介质发挥作用。最近，mTORC2被鉴定为负责通过其疏水基序（HM）中的关键同源残基的磷酸化来激活这些激酶的激酶。由于诱导mTORC2活性的刺激物（如胰岛素和IGF1）触发SGK1和Akt的磷酸化，因此mTORC2如何能够调节这些相关激酶的活性，从而使其介导对电解质平衡和能量代谢的不同影响尚不清楚。值得注意的是，除了其在离子平衡中的公认作用外，肾脏还发挥着重要作用。 由于其显著的促代谢能力，在整个动物能量稳态中起重要作用。目前尚不清楚肾脏如何能够从多个信号传导途径中分选串扰，以允许其代谢和离子平衡功能的适当的上下文依赖性调节。因此，了解mTORC2选择性激活SGK1和Akt的分子动力学，在体外和体内，是开放和重要的研究领域。Gleason博士将以她在代谢生理学和信号转导方面的背景为基础，在离子转运过程的细胞和整个动物研究中进行额外的培训，以解决mTORC 2对SGK 1与Akt的特异性的机制基础，以及它们在细胞和整个动物水平上的功能意义，通过两个具体目标：1）研究调节SGK1相对于Akt的mTORC 2特异性活化的激素刺激和/或细胞条件。2)表征Akt和SGK1对体内肾脏葡萄糖代谢和离子平衡的相对贡献。K01导师职业发展奖提供的培训期将为格里森博士提供一个全面的工具箱，用于她独立的职业生涯，调查代谢与健康和疾病中不同信号通路的交叉点。

DESCRIPTION (provided by applicant): The overall goal of this research proposal is to further elucidate the molecular mechanisms that underlie mTORC2 target specificity and their functional implications in the regulation of glucose homeostasis and ion balance, using biochemical, electrophysiological, metabolic, genetic and whole animal physiology techniques. The applicant for the K01 Mentored Career Development Award, Dr. Catherine E. Gleason, is currently a postdoctoral fellow in Dr. David Pearce's laboratory at UCSF. Dr. Gleason's long-term research goal is to study how metabolic signaling pathways intersect and influence pathways controlling various biological functions, notably ion balance by the kidney, for maintenance of physiological homeostasis. Dr. Gleason's long-term career goal is to establish an independent molecular physiology research program as a tenure-track investigator at an academic institution. SGK1 and Akt are highly related protein kinases that function as key mediators of the signaling pathways that control ion and metabolic homeostasis, respectively. Recently, mTORC2 was identified as the kinase responsible for activation of these kinases by phosphorylation of a critical, homologous residue in their hydrophobic motif (HM). Since, stimuli that induce mTORC2 activity, such as insulin and IGF1, trigger phosphorylation of both SGK1 and Akt, how mTORC2 is able to modulate activity of these related kinases in such a way that allows them to mediate distinct effects on electrolyte balance and energy metabolism is not understood. Notably, in addition to its well-established role in ion balance, the kidney also plays an important role in whole animal energy homeostasis due to its significant gluconeogenic capacity. It is unclear how the kidney is able to sort crosstalk from multiple signaling pathways to allow for appropriate, context-dependent regulation of its metabolic and ion balance functions. Thus, understanding the molecular dynamics surrounding mTORC2 selective activation of SGK1 and Akt, in vitro and in vivo, are open and important areas for investigation. Dr. Gleason will build on her background in metabolic physiology and signal transduction with additional training in the cellular and whole animal study of ion transport processes to address the mechanistic basis for mTORC2 specificity towards SGK1 vs. Akt and their functional implications at the cellular and whole animal levels through two specific aims: 1) Investigate the hormonal stimuli and/or cellular conditions that regulate mTORC2 specific activation of SGK1 vs. Akt. 2) Characterize the relative contributions of Akt and SGK1 towards renal glucose metabolism and ion balance in vivo. The training period provided by the K01 Mentored Career Development Award will provide Dr. Gleason with a comprehensive toolbox for her independent career investigating the intersections of metabolism with diverse signaling pathways in health and disease.