Autophagy prevents runaway meiotic divisions

Area of Science:

• Cell Biology
• Genetics
• Molecular Biology

Background:

• Macroautophagy (autophagy) is essential for entry into meiotic divisions in budding yeast.
• Previous work demonstrated autophagy's requirement for meiotic exit.

Purpose of the Study:

• To investigate the role of autophagy in meiotic exit.
• To elucidate the molecular mechanisms by which autophagy controls meiotic exit.

Main Methods:

• Inhibition of autophagy during meiotic entry in budding yeast.
• Analysis of spindle formation, chromosome segregation, and cell viability.
• Assessment of cyclin Clb3 levels and anaphase-promoting complex/cyclosome (APC/C) substrate degradation.
• Identification of autophagy substrates, including the translational repressor Rim4.

Main Results:

• Autophagy inhibition leads to aberrant spindle formation, chromosome segregation, and cell death.
• Meiosis II-specific cyclin Clb3 is absent, and APC/C substrates persist when autophagy is inhibited.
• The translational repressor Rim4 is identified as a substrate of autophagy.
• Rim4's known function in repressing Clb3 synthesis and Ama1 activity explains the observed phenotypes.

Conclusions:

• Autophagy controls meiotic exit by regulating the degradation of key proteins.
• Timed autophagic degradation of Rim4, a master regulator of gene expression, is critical for proper meiotic exit.
• These findings provide new mechanistic insights into the control of meiotic progression.