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RASAL2 (RAS protein activator like 2), a RASGTPase activating protein, can catalyze the hydrolysis of RAS-GTP into RAS-GDP to inactivate the RAS pathway in various types of cancer cells. However, the cellular function of RASAL2 remains elusive. Here we showed that RASAL2 can attenuate PRKAA/AMPKα phosphorylation by recruiting phosphatase PPM1B/pp2cβ, thus inhibiting the initiation of basal autophagy under normal conditions. In addition, we found that glucose starvation could induce dissociation of PPM1B from RASAL2 and then RASAL2 at S351 be phosphorylated by PRKAA, followed by the binding of phosphorylated-RASAL2 with to PIK3C3/VPS34-ATG14-BECN1/Beclin1 complex to increase PIK3C3 activity and autophagy. Furthermore, RASAL2 S351 phosphorylation facilitated breast tumor growth and correlated to poor clinical outcomes in breast cancer patients. Our study demonstrated that the phosphorylation status of RASAL2 S351 can function as a molecular switch to either suppress or promote AMPK-mediated autophagy. Inhibition of RASAL2 S351 phosphorylation might be a potential therapeutic strategy to overcome the resistance of AMPK-activation agents. Abbreviations: AICAR: aminoimidazole carboxamide ribonucleotide; AMPK: adenosine 5'-monophosphate (AMP)-activated protein kinase; ATG14: autophagy related 14; C.C: compound C; CQ: chloroquine; DKO: double-knockout; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PIK3R4/VPS15: phosphoinositide-3-kinase regulatory subunit 4; PPM1B/pp2cβ: protein phosphatase, Mg2+/Mn2+ dependent 1B; PRKAA/AMPKα: protein kinase AMP-activated catalytic subunit alpha; PtdIns: phosphatidylinositol; PtdIns3P: phosphatidylinositol-3-phosphate; RASAL2: RAS protein activator like 2; RasGAPs: RasGTPase activating proteins; SQSTM1/p62: sequestosome 1; TNBC: triple-negative breast cancer. [ABSTRACT FROM AUTHOR]

Macroautophagy/autophagy, a cellular process that sequesters and breaks down cellular components in the lysosome/vacuole, is important in various events where cell composition undergoes changes. Broadly, autophagy is involved in T cell regulation including maintaining cell homeostasis. One process where a cell alters its composition is in the activation of helper T cells in the immune system. When helper (CD4+) T cells are activated by antigens, they both grow and alter their cellular components to become effector T cells. Autophagy is the process that facilitates the breakdown of these cellular components and is therefore hypothesized to have a role in CD4+ T cell activation. Previous research has concluded that CD4+ T cell activation induces autophagy, providing an avenue for further research aimed at examining the ways in which this induced autophagy affects CD4+ T cell proliferation and function. Toward this end, Zhou et al. researched the autophagosomal cargo present within CD4+ T cells and the impact this cargo has on CD4+ T cell proliferation. [ABSTRACT FROM AUTHOR]