Selective degradation of
protein aggregates by macroautophagy/autophagy is an essential homeostatic process of safeguarding cells from the effects of proteotoxicity. Among the
ubiquitin-like proteins, NEDD8 conjugation to misfolded
proteins is prominent in stress-induced
protein aggregates, albeit the function of neddylation in autophagy is unclear. Here, we report that polyneddylation functions as a post-translational modification for autophagic degradation of proteotoxic-stress induced
protein aggregates. We also show that HYPK functions as an autophagy receptor in the polyneddylation-dependent aggrephagy. The scaffolding function of HYPK is facilitated by its C-terminal
ubiquitin-associated domain and N-terminal
tyrosine-type LC3-interacting region which bind to NEDD8 and LC3 respectively. Both NEDD8 and HYPK are positive modulators of basal and proteotoxicity-induced autophagy, leading to protection of cells from
protein aggregates, such as aggregates of mutant HTT exon 1. Thus, we propose an indispensable and additive role of neddylation and HYPK in clearance of
protein aggregates by autophagy, resulting in cytoprotective effect during proteotoxic stress.Abbreviations: ATG5, autophagy related 5; ATG12, autophagy related 12; ATG14, autophagy related 14; BECN1,
beclin 1; CBL, casitas B-lineage
lymphoma; CBLB, Cbl proto-oncogene B; GABARAP,
GABA type A receptor-associated
protein; GABARAPL1,
GABA type A receptor associated
protein like 1; GABARAPL2,
GABA type A receptor associated
protein like 2; GFP,
green fluorescent protein; HTT, huntingtin; HTT97Q exon 1, huntingtin 97-glutamine exon 1; HUWE1, HECT, UBA and WWE domain containing E3
ubiquitin protein ligase 1; HYPK, huntingtin interacting
protein K;
IgG,
immunoglobulin G; IMR-32, Institute for Medical Research-32; KD, knockdown; Kd, dissociation constant; LAMP1,
lysosomal associated membrane protein 1; LIR, LC3 interacting region; MAP1LC3/LC3,
microtubule associated protein 1 light chain 3; MAP1LC3A/LC3A,
microtubule associated protein 1 light chain 3 alpha; MAP1LC3B/LC3B,
microtubule associated protein 1 light chain 3 beta; MARK1, microtubule affinity regulating
kinase 1; MARK2, microtubule affinity regulating
kinase 2; MARK3, microtubule affinity regulating
kinase 3; MARK4, microtubule affinity regulating
kinase 4; MCF7, Michigan
Cancer Foundation-7; MTOR, mechanistic target of
rapamycin kinase; NAE1, NEDD8 activating
enzyme E1 subunit 1; NBR1, NBR1 autophagy cargo receptor; NEDD8, NEDD8
ubiquitin like modifier; Ni-NTA,
nickel-nitrilotriacetic acid; NUB1, negative regulator of
ubiquitin like proteins 1; PIK3C3,
phosphatidylinositol 3-kinase catalytic subunit type 3;
PolyQ,
poly-glutamine; PSMD8,
proteasome 26S subunit, non-
ATPase 8; RAD23A, RAD23 homolog A, nucleotide excision repair
protein; RAD23B, RAD23 homolog B, nucleotide excision repair
protein; RFP,
red fluorescent protein; RPS27A,
ribosomal protein S27a; RSC1A1, regulator of solute carriers 1; SNCA,
synuclein alpha; SIK1,
salt inducible
kinase 1;
siRNA, small interfering
ribonucleic acid; SOD1,
superoxide dismutase 1; SPR, surface plasmon resonance; SQSTM1, sequestosome 1; SUMO1, small
ubiquitin like modifier 1; TAX1BP1, Tax1
binding protein 1; TDRD3, tudor domain containing 3; TNRC6C, trinucleotide repeat containing adaptor 6C; TOLLIP, toll interacting
protein; TUBA,
tubulin alpha; TUBB,
tubulin beta class I; UBA,
ubiquitin-associated; UBA1,
ubiquitin like modifier activating
enzyme 1; UBA5,
ubiquitin like modifier activating
enzyme 5; UBAC1, UBA domain containing 1; UBAC2, UBA domain containing 2; UBAP1,
ubiquitin associated
protein 1; UBAP2,
ubiquitin associated
protein 2; UBASH3B,
ubiquitin associated and SH3 domain containing B; UBD/FAT10,
ubiquitin D; UBE2K,
ubiquitin conjugating enzyme E2 K; UBLs,
ubiquitin-like proteins; UBL7,
ubiquitin like 7; UBQLN1, ubiquilin 1; UBQLN2, ubiquilin 2; UBQLN3, ubiquilin 3; UBQLN4, ubiquilin 4; UBXN1, UBX domain protein 1; ULK1,
unc-51 like autophagy activating kinase 1; URM1,
ubiquitin related modifier 1; USP5,
ubiquitin specific peptidase 5; USP13,
ubiquitin specific peptidase 13; VPS13D, vacuolar protein sorting 13 homolog D.