Mutual regulation between cell cycle and transcription termination factor TTF2.

Area of Science:

• Molecular Biology
• Cell Biology
• Cancer Biology

Background:

• Transcriptional activity is typically silenced during mitosis and reactivated upon mitotic exit.
• The precise mechanisms governing this transcriptional regulation during the cell cycle remain largely unknown.

Purpose of the Study:

• To elucidate the role of transcription termination factor TTF2 in cell cycle regulation.
• To investigate the interplay between TTF2, the anaphase-promoting complex/cyclosome (APC/C), and the mitotic checkpoint complex (MCC).

Main Methods:

• Protein level analysis of TTF2 during cell cycle progression.
• Knockdown and overexpression studies of TTF2.
• Ubiquitination assays to study TTF2 degradation by APC/C^CDH1.
• Analysis of TTF2 binding to CDC20 and MCC formation.

Main Results:

• TTF2 protein levels oscillate, increasing in S and G2/M phases and decreasing in late mitosis and G1.
• TTF2 knockdown causes G2/M arrest; TTF2 overexpression accelerates M/G1 transition and promotes proliferation.
• TTF2 is ubiquitinated by APC/C^CDH1 and degraded by the proteasome.
• TTF2 inhibits MCC formation by binding CDC20 during normal mitosis.
• During G2/M arrest, TTF2 degradation by APC/C^CDH1 releases CDC20, promoting MCC assembly.
• TTF2 is overexpressed in solid tumors and correlates with poor patient survival.

Conclusions:

• TTF2 acts as a crucial link between transcription termination and cell cycle regulation.
• TTF2 plays dual roles in mitosis by modulating APC/C and MCC activity.
• TTF2 dysregulation contributes to tumorigenesis and poor prognosis in solid tumors.