AMPK inhibits ULK1-dependent autophagosome formation and lysosomal acidification via distinct mechanisms

Chinwendu Nwadike, Leon E. Williamson, Laura E. Gallagher, Jun-Lin Guan, Edmond Y.W. Chan

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Autophagy maintains metabolism in response to starvation but each nutrient is sensed distinctly. Amino acid deficiency suppresses mechanistic target of rapamycin complex 1 (MTORC1) while glucose deficiency promotes AMP-activated protein kinase (AMPK). MTORC1 and AMPK signalling pathways converge onto the ULK1/2 autophagy initiation complex. Here, we show that amino acid starvation promoted formation of ULK1- and Sequestosome1/p62-positive early autophagosomes. Autophagosome initiation was controlled by MTORC1 sensing glutamine, leucine and arginine levels together. By contrast, glucose starvation promoted AMPK activity, phosphorylation of ULK1 Ser 555 and LC3-II accumulation, but with dynamics consistent with a block in autophagy flux. We studied the flux pathway and found that starvation of amino acid, but not of glucose, activated lysosomal acidification, which occurred independently of autophagy and ULK1. Further to lack of activation, glucose starvation inhibited the ability of amino acid starvation to activate both autophagosome formation and the lysosome. Activation of AMPK and phosphorylation of ULK1 were determined to specifically inhibit autophagosome formation. AMPK activation also was sufficient to prevent lysosome acidification. These results indicate concerted but distinct AMPK-dependent mechanisms to suppress early and late phases of autophagy.
LanguageEnglish
Article numbere00023-18
Number of pages22
JournalMolecular and Cellular Biology
Volume38
Issue number10
Early online date5 Mar 2018
DOIs
Publication statusPublished - 31 May 2018

Fingerprint

AMP-Activated Protein Kinases
Starvation
Autophagy
Amino Acids
Glucose
Lysosomes
Phosphorylation
Glutamine
Leucine
Arginine
Autophagosomes
Food
mechanistic target of rapamycin complex 1

Keywords

  • autophagy
  • amino acid starvation
  • glucose starvation
  • ULK1
  • MTORC1
  • AMPK
  • leucine
  • glutamine
  • arginine
  • lysosome acidification

Cite this

Nwadike, Chinwendu ; Williamson, Leon E. ; Gallagher, Laura E. ; Guan, Jun-Lin ; Chan, Edmond Y.W. / AMPK inhibits ULK1-dependent autophagosome formation and lysosomal acidification via distinct mechanisms. In: Molecular and Cellular Biology. 2018 ; Vol. 38, No. 10.
@article{981b05f8e9ed4952a89e953c6d8c9666,
title = "AMPK inhibits ULK1-dependent autophagosome formation and lysosomal acidification via distinct mechanisms",
abstract = "Autophagy maintains metabolism in response to starvation but each nutrient is sensed distinctly. Amino acid deficiency suppresses mechanistic target of rapamycin complex 1 (MTORC1) while glucose deficiency promotes AMP-activated protein kinase (AMPK). MTORC1 and AMPK signalling pathways converge onto the ULK1/2 autophagy initiation complex. Here, we show that amino acid starvation promoted formation of ULK1- and Sequestosome1/p62-positive early autophagosomes. Autophagosome initiation was controlled by MTORC1 sensing glutamine, leucine and arginine levels together. By contrast, glucose starvation promoted AMPK activity, phosphorylation of ULK1 Ser 555 and LC3-II accumulation, but with dynamics consistent with a block in autophagy flux. We studied the flux pathway and found that starvation of amino acid, but not of glucose, activated lysosomal acidification, which occurred independently of autophagy and ULK1. Further to lack of activation, glucose starvation inhibited the ability of amino acid starvation to activate both autophagosome formation and the lysosome. Activation of AMPK and phosphorylation of ULK1 were determined to specifically inhibit autophagosome formation. AMPK activation also was sufficient to prevent lysosome acidification. These results indicate concerted but distinct AMPK-dependent mechanisms to suppress early and late phases of autophagy.",
keywords = "autophagy, amino acid starvation, glucose starvation, ULK1, MTORC1, AMPK, leucine, glutamine, arginine, lysosome acidification",
author = "Chinwendu Nwadike and Williamson, {Leon E.} and Gallagher, {Laura E.} and Jun-Lin Guan and Chan, {Edmond Y.W.}",
year = "2018",
month = "5",
day = "31",
doi = "10.1128/MCB.00023-18",
language = "English",
volume = "38",
journal = "Molecular and Cellular Biology",
issn = "0270-7306",
number = "10",

}

AMPK inhibits ULK1-dependent autophagosome formation and lysosomal acidification via distinct mechanisms. / Nwadike, Chinwendu; Williamson, Leon E.; Gallagher, Laura E.; Guan, Jun-Lin; Chan, Edmond Y.W.

In: Molecular and Cellular Biology, Vol. 38, No. 10, e00023-18, 31.05.2018.

Research output: Contribution to journalArticle

TY - JOUR

T1 - AMPK inhibits ULK1-dependent autophagosome formation and lysosomal acidification via distinct mechanisms

AU - Nwadike, Chinwendu

AU - Williamson, Leon E.

AU - Gallagher, Laura E.

AU - Guan, Jun-Lin

AU - Chan, Edmond Y.W.

PY - 2018/5/31

Y1 - 2018/5/31

N2 - Autophagy maintains metabolism in response to starvation but each nutrient is sensed distinctly. Amino acid deficiency suppresses mechanistic target of rapamycin complex 1 (MTORC1) while glucose deficiency promotes AMP-activated protein kinase (AMPK). MTORC1 and AMPK signalling pathways converge onto the ULK1/2 autophagy initiation complex. Here, we show that amino acid starvation promoted formation of ULK1- and Sequestosome1/p62-positive early autophagosomes. Autophagosome initiation was controlled by MTORC1 sensing glutamine, leucine and arginine levels together. By contrast, glucose starvation promoted AMPK activity, phosphorylation of ULK1 Ser 555 and LC3-II accumulation, but with dynamics consistent with a block in autophagy flux. We studied the flux pathway and found that starvation of amino acid, but not of glucose, activated lysosomal acidification, which occurred independently of autophagy and ULK1. Further to lack of activation, glucose starvation inhibited the ability of amino acid starvation to activate both autophagosome formation and the lysosome. Activation of AMPK and phosphorylation of ULK1 were determined to specifically inhibit autophagosome formation. AMPK activation also was sufficient to prevent lysosome acidification. These results indicate concerted but distinct AMPK-dependent mechanisms to suppress early and late phases of autophagy.

AB - Autophagy maintains metabolism in response to starvation but each nutrient is sensed distinctly. Amino acid deficiency suppresses mechanistic target of rapamycin complex 1 (MTORC1) while glucose deficiency promotes AMP-activated protein kinase (AMPK). MTORC1 and AMPK signalling pathways converge onto the ULK1/2 autophagy initiation complex. Here, we show that amino acid starvation promoted formation of ULK1- and Sequestosome1/p62-positive early autophagosomes. Autophagosome initiation was controlled by MTORC1 sensing glutamine, leucine and arginine levels together. By contrast, glucose starvation promoted AMPK activity, phosphorylation of ULK1 Ser 555 and LC3-II accumulation, but with dynamics consistent with a block in autophagy flux. We studied the flux pathway and found that starvation of amino acid, but not of glucose, activated lysosomal acidification, which occurred independently of autophagy and ULK1. Further to lack of activation, glucose starvation inhibited the ability of amino acid starvation to activate both autophagosome formation and the lysosome. Activation of AMPK and phosphorylation of ULK1 were determined to specifically inhibit autophagosome formation. AMPK activation also was sufficient to prevent lysosome acidification. These results indicate concerted but distinct AMPK-dependent mechanisms to suppress early and late phases of autophagy.

KW - autophagy

KW - amino acid starvation

KW - glucose starvation

KW - ULK1

KW - MTORC1

KW - AMPK

KW - leucine

KW - glutamine

KW - arginine

KW - lysosome acidification

UR - http://mcb.asm.org/

U2 - 10.1128/MCB.00023-18

DO - 10.1128/MCB.00023-18

M3 - Article

VL - 38

JO - Molecular and Cellular Biology

T2 - Molecular and Cellular Biology

JF - Molecular and Cellular Biology

SN - 0270-7306

IS - 10

M1 - e00023-18

ER -