Macroautophagy/autophagy is a cellular process in which cytosolic contents are degraded
by lysosome in response to various stress conditions. Apart from its role in the maintenance
of cellular homeostasis, autophagy also involves in regulation of cell cycle progression
under nutrient-deprivation conditions. However, whether and how autophagy is regulated
by the cell cycle especially during mitosis remains largely undefined. Here we show
that WIPI2/ATG18B (WD repeat domain, phosphoinositide interacting 2), an autophagy-related
(ATG) protein that plays a critical role in autophagosome biogenesis, is a direct
substrate of CUL4-RING ubiquitin ligases (CRL4s). Upon mitosis induction, CRL4s are
activated via neddylation, and recruit WIPI2 via DDB1 (damage specific DNA binding
protein 1), leading to polyubiquitination and proteasomal degradation of WIPI2 and
suppression of autophagy. The WIPI2 protein level and autophagy during mitosis could
be rescued by knockdown of CRL4s or treatment with MLN4924/Pevonedistat, a selective
inhibitor of CRLs, via suppression of NAE1 (NEDD8 activating enzyme E1 subunit 1).
Moreover, restoration of WIPI2 rescues autophagy during mitosis and leads to mitotic
slippage and cell senescence. Our study thus discovers a novel function of CRL4s in
autophagy by targeting WIPI2 for polyubiquitination and proteasomal degradation during
mitosis. Abbreviations : ACTB, actin beta; ATG, autophagy-related; AMPK, AMP-activated
protein kinase; AURKB/ARK2, aurora kinase B; BafA1, bafilomycin A 1 ; CCNB1, cyclin
B1; CDK1, cyclin dependent kinase 1; CHX, cycloheximide; CQ, chloroquine; CRL4s, CUL4-RING
ubiquitin ligases; DDB1, damage specific DNA binding protein 1; GAPDH, glyceraldehyde-3-phosphate
dehydrogenase; GFP, green fluorescent protein; GST, glutathione S-transferase; MAP1LC3B/LC3B,
microtubule associated protein 1 light chain 3 beta; STK11/LKB1,serine/threonine kinase
11; MTORC1/MTOR complex 1, mechanistic target of rapamycin kinase complex 1; NAE1,
NEDD8 activating enzyme E1 subunit 1; NOC, nocodazole; RING, really interesting new
gene; RBX1, ring-box 1; SA-GLB1/β-gal, senescence-associated galactosidase beta 1;
TSC2, TSC complex subunit 2; TUBA, tubulin alpha; WIPI2, WD repeat domain, phosphoinositide
interacting 2