The evi5 oncogene regulates cyclin accumulation by stabilizing the anaphase-promoting complex inhibitor emi1

Area of Science:

• Cell Biology
• Molecular Biology
• Oncogenes

Background:

• The anaphase-promoting complex/cyclosome (APC/C) is crucial for cell-cycle progression.
• Emi1 is a key inhibitor of the APC/C, regulating entry into mitosis.
• Maintaining proper Emi1 levels is essential for preventing cell-cycle errors.

Purpose of the Study:

• To identify regulators of Emi1 accumulation.
• To elucidate the mechanism by which Evi5 controls Emi1 stability.
• To understand the role of Evi5 in maintaining cell-cycle fidelity.

Main Methods:

• Co-immunoprecipitation to identify Emi1 binding proteins.
• Analysis of protein degradation pathways.
• Cell-cycle analysis and centrosome duplication assays.

Main Results:

• Evi5 was identified as an Emi1-binding protein that stabilizes Emi1.
• Evi5 antagonizes SCF(betaTrCP)-mediated Emi1 ubiquitination and degradation.
• Evi5 ablation leads to precocious APC/C activation, cell-cycle arrest, and mitotic catastrophe.

Conclusions:

• Evi5 acts as a crucial stabilizing factor for Emi1 during the S/G2 phase.
• The balance between Evi5 and Polo-like kinase activities regulates Emi1 and cyclin levels.
• This balance is critical for ensuring accurate cell-cycle progression and mitotic fidelity.