A Chemogenetic CRISPR Knock-out Screen Uncovers Synergy Between Ubiquitin Signaling and C16orf72/HAPSTR1 for S-phase Entry

ABSTRACT: Cell cycle progression is orchestrated by complex interplay between post-translational modifications (PTMs) controlling activation (phosphorylation) and degradation (ubiquitination) of key cell cycle regulators. To comprehensively identify ubiquitin signalling components critical for cell proliferation, we employed a chemical-genetic CRISPR knock-out screen exploiting the first-in-class ubiquitin E1 inhibitor TAK243. We identified 239 genes, including C16orf72/HAPSTR1, whose mutation rendered cells sensitive and 55 genes conferring resistance to diminished ubiquitin signaling, providing a systems view of key protein networks underpinning cell cycle progression. Proteome-wide alterations in the ubiquitin signaling landscape as a function of HAPSTR1 expression, revealed increased ubiquitination of the cell cycle regulator CDK6. Mechanistically, we find that HAPSTR1 controls the timing of S-phase entry via RB-E2F1 pathway activation by CDK6. Strikingly, the HAPSTR1/CDK6 axis is finetuned by the ubiquitin proteasome system (UPS), enforcing cell cycle-dependent turnover of both proteins. Although CDKs have long been thought of as stable elements of the cell cycle machinery, this conventional notion is challenged by our present findings, demonstrating UPS-dependent fluctuations in CDK6 expression. Altogether, we provide a valuable resource on the interplay between the ubiquitin system and cell proliferation and uncover HAPSTR1 as a regulator of CDK6 levels to orchestrate G1/S transition.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell

SUBMITTER: Vyacheslav Akimov  

LAB HEAD: Dr. Blagoy Blagoev

PROVIDER: PXD050046 | Pride | 2026-09-07

REPOSITORIES: Pride