Hsu Cynthia L, Lee Elian X, Gordon Kara L, Paz Edwin A, Shen Wen-Chuan, Ohnishi Kohta, Meisenhelder Jill, Hunter Tony, La Spada Albert R
Department of Pediatrics, University of California, San Diego, La Jolla, CA, 92093, USA.
Departments of Neurology, Neurobiology, and Cell Biology, Duke Center for Neurodegeneration and Neurotherapeutics, Duke University School of Medicine, Durham, NC, 27710, USA.
Nat Commun. 2018 Mar 5;9(1):942. doi: 10.1038/s41467-018-03340-7.
Autophagy is the major cellular pathway by which macromolecules are degraded, and amino acid depletion powerfully activates autophagy. MAP4K3, or germinal-center kinase-like kinase, is required for robust cell growth in response to amino acids, but the basis for MAP4K3 regulation of cellular metabolic disposition remains unknown. Here we identify MAP4K3 as an amino acid-dependent regulator of autophagy through its phosphorylation of transcription factor EB (TFEB), a transcriptional activator of autophagy, and through amino acid starvation-dependent lysosomal localization of MAP4K3. We document that MAP4K3 physically interacts with TFEB and MAP4K3 inhibition is sufficient for TFEB nuclear localization, target gene transactivation, and autophagy, even when mTORC1 is activated. Moreover, MAP4K3 serine 3 phosphorylation of TFEB is required for TFEB interaction with mTORC1-Rag GTPase-Ragulator complex and TFEB cytosolic sequestration. Our results uncover a role for MAP4K3 in the control of autophagy and reveal MAP4K3 as a central node in nutrient-sensing regulation.
自噬是大分子降解的主要细胞途径，氨基酸耗竭可有力地激活自噬。丝裂原活化蛋白激酶4激酶3（MAP4K3），即生发中心激酶样激酶，是细胞对氨基酸作出反应实现强劲生长所必需的，但MAP4K3调节细胞代谢状态的基础仍不清楚。在此，我们通过转录因子EB（TFEB，一种自噬转录激活因子）的磷酸化以及MAP4K3在氨基酸饥饿依赖的溶酶体定位，确定MAP4K3是自噬的氨基酸依赖性调节因子。我们证明，即使在mTORC1被激活的情况下，MAP4K3与TFEB发生物理相互作用，且抑制MAP4K3足以实现TFEB核定位、靶基因反式激活和自噬。此外，TFEB与mTORC1-Rag GTP酶-Ragulator复合物相互作用以及TFEB胞质隔离需要MAP4K3对TFEB的丝氨酸3进行磷酸化。我们的结果揭示了MAP4K3在自噬控制中的作用，并表明MAP4K3是营养感应调节中的一个中心节点。
