UHRF2 accumulates in early G₁-phase after serum stimulation or mitotic exit to extend G₁ and total cell cycle length

ABSTRACT

Ubiquitin like with PHD and ring finger domains 2 (UHRF2) regulates the cell cycle and epigenetics as a multi-domain protein sharing homology with UHRF1. UHRF1 functions with DNMT1 to coordinate daughter strand methylation during DNA replication, but UHRF2 can’t perform this function, and its roles during cell cycle progression are not well defined. UHRF2 role as an oncogene vs. tumor suppressor differs in distinct cell types. UHRF2 interacts with E2F1 to control Cyclin E1 (CCNE1) transcription. UHRF2 also functions in a reciprocal loop with Cyclin E/CDK2 during G₁, first as a direct target of CDK2 phosphorylation, but also as an E3-ligase with direct activity toward both Cyclin E and Cyclin D. In this study, we demonstrate that UHRF2 is expressed in early G₁ following either serum stimulation out of quiescence or in cells transiting directly out of M-phase, where UHRF2 protein is lost. Further, UHRF2 depletion in G2/M is reversed with a CDK1 specific inhibitor. UHRF2 controls expression levels of cyclins and CDK inhibitors and controls its own transcription in a negative-feedback loop. Deletion of UHRF2 using CRISPR/Cas9 caused a delay in passage through each cell cycle phase. UHRF2 loss culminated in elevated levels of cyclins but also the CDK inhibitor p27^KIP1, which regulates G₁ passage, to reduce retinoblastoma phosphorylation and increase the amount of time required to reach G₁/S passage. Our data indicate that UHRF2 is a central regulator of cell-cycle pacing through its complex regulation of cell cycle gene expression and protein stability.

KEYWORDS:

• UHRF2
• cell cycle
• cyclin/Cdk
• FUCCI

Acknowledgements

We thank Dr. Xiaochun Yu for providing the ΔRing Uhrf2 plasmid. We thank Dr. Catriona Jamieson for providing the Fucci2BL plasmid (24). We also thank the University of Minnesota Flow cytometry resource core facility for assisting with cell sorting and flow cytometry. We thank Brian Ruis in the Genome Engineering Shared Resource for assisting with CRISPR/Cas9 reagent design and use.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15384101.2024.2353553

Author contributions

X.W. and T.C.H. designed and supervised this study, interpreted data, and wrote the paper. X.W. H.L. and G.S. performed experiments, collected and analyzed data.

Additional information

Funding

This work was funded by grants to T.C.H. from N.I.H. [R01CA168622], Children’s Cancer Research Fund, Minneapolis, MN, and Minnesota Masonic Charities.