MAP4K3 mediates amino acid-dependent regulation of autophagy via phosphorylation of TFEB

Cynthia L Hsu,Tony Hunter,Kohta Ohnishi,Albert R La Spada,Jill Meisenhelder,Wen-Chuan Shen,Elian X Lee,Edwin A Paz,Kara L Gordon

doi:10.1038/s41467-018-03340-7

Abstract

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.

Highlights

Autophagy is the major cellular pathway by which macromolecules are degraded, and amino acid depletion powerfully activates autophagy
In response to amino acid stimulation, mechanistic target of rapamycin complex 1 (mTORC1) is recruited to the cytosolic surface of lysosomes via a physical interaction between Raptor, a set of membrane-bound lysosomal proteins known as the Ragulator complex, and the Rag GTPases, which function as heterodimers wherein the active complex consists of GTP-bound RagA or B complexed with GDP-bound RagC or D16, 17
As transcription factor EB (TFEB) entry into the nucleus is required for transactivation of its target genes and inhibition of TFEB by mTORC1 phosphorylation restricts TFEB to the cytosol, we examined the effect of MAP4K3 loss-of-function on TFEB subcellular localization

Summary

Introduction

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. Autophagy refers to a set of three cellular processes, i.e., macroautophagy, chaperone-mediated autophagy, and microautophagy, each of which achieve the sequestration and delivery of cytosolic cargoes to the lysosome for degradation. We recently discovered that knock-down of MAP4K3 is sufficient to induce autophagy[15] and so considered the current model of amino-acid-dependent autophagy regulation According to this model, in response to amino acid stimulation, mTORC1 is recruited to the cytosolic surface of lysosomes via a physical interaction between Raptor, a set of membrane-bound lysosomal proteins known as the Ragulator complex, and the Rag GTPases, which function as heterodimers wherein the active complex consists of GTP-bound RagA or B complexed with GDP-bound RagC or D16, 17. Arginine is sensed in the cytosol by CASTOR1, which binds to and inhibits

Methods

Results

Conclusion