Investigation of a novel protein complex that couples regulation of lysosomal function to intracellular nutrient availability

 描述（由申请人提供）：细胞通过调节生长和生物合成活动来响应营养物质可用性的变化。营养丰富的条件促进合成代谢过程，如蛋白质和脂质合成，而营养贫乏的条件促进分解代谢过程，如溶酶体内大分子的降解。此外，溶酶体还作为一个信号平台，帮助细胞协调它们对营养物质可用性变化的反应。例如，mTORC 1（细胞生长和代谢的中心协调者）的激活受其营养调节的溶酶体表面募集的调节，随后可通过生长因子信号激活。考虑到mTORC 1在健康和疾病中作为细胞生长调节剂的主要作用，目前对直接感测和/或鉴定溶酶体蛋白的鉴定和功能表征存在强烈兴趣。 对养分有效性的变化作出反应。我们的实验室最近确定了一个关键的溶酶体定位的作用，卵泡素（FLCN），Birt-Hogg-Dubé综合征的肿瘤抑制因子，在激活mTORC 1的细胞内氨基酸。该提案的目标是定义一种新型蛋白质复合物的作用，该蛋白质复合物由预测在基于溶酶体的营养感测和信号传导途径中与FLCN结构同源的蛋白质组成。我将通过使用生物化学，遗传和基于细胞的测定来研究这些蛋白质的功能，以验证我的假设，即这些蛋白质有助于溶酶体感知和响应营养物质可用性持续变化的能力。拟议的研究与NIH的使命广泛相关，因为在癌症中经常观察到营养对细胞生长的限制失调。这一点在mTORC 1信号在超过一半的肿瘤中被过度激活的报道中得到了最好的强调。异常mTORC 1信号传导也与神经系统疾病有关。这些例子说明了定义允许溶酶体响应细胞内营养物质可用性的分子机制对人类健康的重要性。

 DESCRIPTION (provided by applicant): Cells respond to changes in nutrient availability by adjusting growth and biosynthetic activities. Nutrient rich conditions promote anabolic processes such as protein and lipid synthesis, while nutrient poor conditions promote catabolic processes such as the degradation of macromolecules within lysosomes. Lysosomes furthermore serve as a signaling platform that helps cells to coordinate their responses to changes in nutrient availability. For example, the activation of mTORC1, a central coordinator of cell growth and metabolism, is regulated by its nutrient-regulated recruitment to the surface of lysosomes where it can subsequently be activated by growth factor signals. Given the major role for mTORC1 as a regulator of cell growth in both health and disease, there is currently intense interest in the identification and functional characterization of the lysosomal proteins that directly sense and/or respond to changes in nutrient availability. Our lab recently identified a critical lysosome-localized role for folliculin (FLCN), the Birt-Hogg-Dubé syndrome tumor suppressor, in the activation of mTORC1 by intracellular amino acids. The goal of this proposal is to define the role of a novel protein complex made up of proteins that are predicted to be structurally homologous to FLCN in lysosome-based nutrient sensing and signaling pathways. I will investigate the function of these proteins by using biochemical, genetic and cell-based assays to test my hypothesis that these proteins contribute to the ability of lysosomes to sense and respond to ongoing changes in nutrient availability. The proposed research is broadly relevant to the NIH mission as dysregulation of nutrient-imposed constraints on cell growth are frequently observed in cancer. This is best highlighted by reports that mTORC1 signaling is hyperactivated in more than half of all tumors. Aberrant mTORC1 signaling has also been linked to neurological disease. These examples illustrate how defining the molecular mechanisms that allow lysosomes to respond to intracellular nutrient availability is of importance to human health.