The vacuole/lysosome is required for cell-cycle progression.

Area of Science:

• Cell Biology
• Molecular Biology

Background:

• Organelles are typically distributed to daughter cells through inheritance pathways.
• The existence of alternative mechanisms ensuring organelle presence in all cells remains largely unexplored.

Purpose of the Study:

• To investigate alternative mechanisms for ensuring organelle presence beyond inheritance.
• To elucidate the role of the yeast vacuole in cell-cycle initiation and progression.

Main Methods:

• Investigated vacuole generation when inheritance pathways fail.
• Analyzed cell-cycle progression under conditions of impaired vacuole inheritance and biogenesis.
• Examined the involvement of the TORC1-SCH9 pathway in vacuole-mediated cell-cycle control.

Main Results:

• The yeast vacuole plays a critical role in initiating the cell cycle.
• A new vacuole is generated via an alternative pathway when inheritance fails, preceding the next cell cycle.
• Combined defects in vacuole inheritance and biogenesis lead to cell-cycle arrest in early G1 phase.
• Vacuole's role in cell-cycle progression depends on the TORC1-SCH9 pathway, which signals from a mature vacuole.

Conclusions:

• The yeast vacuole is essential for cell-cycle initiation, independent of inheritance.
• An alternative vacuole generation pathway ensures cell viability.
• These findings suggest a checkpoint mechanism for vacuole/lysosome presence, involving the TORC1-SCH9 pathway.