PRKAA/AMPKα phosphorylation switches the role of RASAL2 from a suppressor to an activator of autophagy

Yong Bao; Christopher Qian; Meng-Yue Liu; Fei Jiang; Xiaoxiao Jiang; Huijuan Liu; Zhuqing Zhang; Fanghui Sun; Ningwei Fu; Zhaoyuan Hou; Ya Ke; Yan Li; Zhong-Ming Qian

doi:10.1080/15548627.2021.1886767

PRKAA/AMPKα phosphorylation switches the role of RASAL2 from a suppressor to an activator of autophagy

Autophagy. 2021 Nov;17(11):3607-3621. doi: 10.1080/15548627.2021.1886767. Epub 2021 Feb 24.

Authors

Yong Bao^{1

2}, Christopher Qian³, Meng-Yue Liu¹, Fei Jiang¹, Xiaoxiao Jiang², Huijuan Liu², Zhuqing Zhang², Fanghui Sun², Ningwei Fu⁴, Zhaoyuan Hou⁵, Ya Ke³, Yan Li⁵, Zhong-Ming Qian¹

Affiliations

¹ Institute of Translational and Precision Medicine, Nantong University, Nantong, China.
² Department of Pharmacology and Biochemistry, Fudan University School of Pharmacy, Shanghai, China.
³ School of Biomedical Sciences and Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Shatin, Hong Kong.
⁴ Department of Anatomy and Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China.
⁵ Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Department of Biochemistry & Molecular Cellular Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China.

Abstract

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.

Keywords: Autophagy; PP1MB; PRKAA; RASAL2; breast cancer.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

AMP-Activated Protein Kinases / metabolism*
Autophagy*
Binding Sites
Breast Neoplasms / metabolism
Breast Neoplasms / pathology
Cell Line, Tumor
Female
GTPase-Activating Proteins / metabolism*
GTPase-Activating Proteins / physiology
Glucose / deficiency
Humans
Phosphorylation
Protein Phosphatase 2C / metabolism

Substances

GTPase-Activating Proteins
RASAL2 protein, human
AMP-Activated Protein Kinases
PPM1B protein, human
Protein Phosphatase 2C
Glucose

Grants and funding

The studies in our laboratories were supported by grants from the National Natural Science Foundation of China [31571195-ZMQ], Hong Kong Research Grants Council (HKRGC)—General Research Fund [14110418,14167817-YK] and Hong Kong Health Medical Research Fund [HMRF_05162236, 06171036-KY].