Romo1 is a negative-feedback regulator of Myc

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Myc protein degradation is primarily mediated by E3 ubiquitin ligases like SCF(Fbw7) and SCF(Skp2).
• The precise mechanism of S-phase kinase-associated protein (Skp2)-mediated Myc degradation remains incompletely understood.
• Understanding Myc regulation is crucial for comprehending cell cycle control and growth signaling.

Purpose of the Study:

• To elucidate the mechanism of Skp2-mediated Myc degradation.
• To investigate the role of reactive oxygen species modulator 1 (Romo1) in Myc regulation.
• To explore the interplay between Myc, Romo1, and reactive oxygen species (ROS) in cell cycle progression.

Main Methods:

• Investigated Myc protein expression and degradation in normal lung fibroblasts.
• Assessed the induction of Romo1 expression by upregulated Myc.
• Examined the role of Romo1 in Skp2-mediated ubiquitylation and degradation of Myc.
• Analyzed the requirement of ROS from Romo1 for cell cycle entry and Myc induction.

Main Results:

• Upregulated Myc induces Romo1 expression, which facilitates Skp2-mediated Myc ubiquitylation and degradation.
• Steady-state Romo1 expression generates ROS necessary for quiescent cell cycle entry.
• Pre-existing Romo1-derived ROS are required for Myc induction.
• Myc-induced Romo1 expression triggers Skp2-mediated Myc degradation, establishing a negative feedback loop.

Conclusions:

• Romo1 plays a dual role in Myc regulation: promoting its degradation via Skp2 and facilitating its induction through ROS generation.
• This study reveals a novel feedback mechanism where Myc induces Romo1, which in turn promotes Myc degradation, thereby fine-tuning cell cycle progression.
• The findings highlight the critical involvement of Romo1 and ROS in the dynamic regulation of Myc protein levels during cell cycle control.