Biology subjects

Emanuele, M. J.

Publications and source records attributed to Emanuele, M. J..

3 recordsLinked to original sources

bioRxiv2021

Cyclin F drives proliferation through SCF-dependent degradation of the retinoblastoma-like tumor suppressor p130/RBL2

Cell cycle gene expression programs fuel proliferation and are dysregulated in many cancers. The retinoblastoma-family proteins, RB, p130/RBL2 and p107/RBL1, coordinately repress cell cycle gene expression, inhibiting proliferation and suppressing tumorigenesis. Ubiquitin-dependent protein degradation is essential to cell cycle control, and numerous proliferative regulators, tumor suppressors, and oncoproteins are ubiquitinated. However, little is known about the role of ubiquitin signaling in controlling RB-family proteins. A systems genetics analysis of several hundred CRISPR/Cas9 loss-of-function screens suggested the potential regulation of the RB-network by cyclin F, a substrate recognition receptor for the SCF family of E3 ligases. We demonstrate that RBL2/p130 is a direct substrate of SCFcyclin F. We map a cyclin F regulatory site to a flexible linker in the p130 pocket domain, and show that this site mediates binding, stability, and ubiquitination. Expression of a non-degradable p130 represses cell cycle gene expression and strongly reduces proliferation. These data suggest that SCFcyclin F plays a key role in the CDK-RB network and raises the possibility that aberrant p130 degradation could dysregulate the cell cycle in human cancers.

cell biology↗

bioRxiv2020

In silico APC/C substrate discovery reveals cell cycle degradation of chromatin regulators including UHRF1

The Anaphase-Promoting Complex/Cyclosome (APC/C) is an E3 ubiquitin ligase and critical regulator of cell cycle progression. Despite its vital role, it has remained challenging to globally map APC/C substrates. By combining orthogonal features of known substrates, we predicted APC/C substrates in silico. This analysis identified many known substrates and suggested numerous candidates. Unexpectedly, chromatin regulatory proteins are enriched among putative substrates and we show that several chromatin proteins bind APC/C, oscillate during the cell cycle and are degraded following APC/C activation, consistent with being direct APC/C substrates. Additional analysis revealed detailed mechanisms of ubiquitylation for UHRF1, a key chromatin regulator involved in histone ubiquitylation and DNA methylation maintenance. Disrupting UHRF1 degradation at mitotic exit accelerates G1-phase cell cycle progression and perturbs global DNA methylation patterning in the genome. We conclude that APC/C coordinates crosstalk between cell cycle and chromatin regulatory proteins. This has potential consequences in normal cell physiology, where the chromatin environment changes depending on proliferative state, as well as in disease.

cell biology↗

bioRxiv2019

Cell cycle oscillators underlying orderly proteolysis of E2F8

E2F8 is a transcriptional repressor that antagonizes the canonical cell cycle transcription factor E2F1. Despite the importance of this atypical E2F family member in cell cycle, apoptosis and cancer, we lack a complete description of the mechanisms that control its dynamics. To address this question, we developed a complementary set of static and dynamic cell-free systems of human origin, which recapitulate inter-mitotic and G1 phases, and a full transition from pro-metaphase to G1. This revealed an interlocking molecular switch controlling E2F8 degradation at mitotic exit, involving dephosphorylation of Cdk1 sites in E2F8 and the activation of APC/CCdh1, but not APC/CCdc20. Further, we revealed a differential stability of E2F8, accounting for its accumulation in late G1 while APC/CCdh1 is still active and suggesting a key role for APC/C in controlling G1-S transcription. Finally, we identified SCF-Cyclin F as the ubiquitin ligase controlling E2F8 in G2-phase. Altogether, our data provide new insights into the regulation of E2F8 throughout the cell cycle, illuminating an extensive coordination between phosphorylation, ubiquitination and transcription in promoting orderly cell cycle progression.

cell biology↗