The endolysosomal adaptor PLEKHM1 is a direct target for both mTOR and MAPK pathways

Abstract

The lysosome is a cellular signalling hub at the point of convergence of endocytic and autophagic pathways, where the contents are degraded and recycled. Pleckstrin homology domain‐containing family member 1 (PLEKHM1) acts as an adaptor to facilitate the fusion of endocytic and autophagic vesicles with the lysosome. However, it is unclear how PLEKHM1 function at the lysosome is controlled. Herein, we show that PLEKHM1 coprecipitates with, and is directly phosphorylated by, mTOR. Using a phosphospecific antibody against Ser432/S435 of PLEKHM1, we show that the same motif is a direct target for ERK2‐mediated phosphorylation in a growth factor‐dependent manner. This dual regulation of PLEKHM1 at a highly conserved region points to a convergence of both growth factor‐ and amino acid‐sensing pathways, placing PLEKHM1 at a critical juncture of cellular metabolism.

TMEM55B links autophagy flux, lysosomal repair, and TFE3 activation in response to oxidative stress

“…Recent evidence has suggested that PLEKHM1 is directly phosphorylated by mTOR and Erk2 MAPK 17 at Ser432/Ser435, while TMEM55B undergoes Erk-dependent phosphorylation in RAW 264.7 macrophages treated with Toll-like receptor ligands 8 . In addition, it is well-established that p38, JNK and Erk1/2 MAPK get strongly activated in response to oxidative stress 18 .…”