FBXL20-mediated Vps34 ubiquitination as a p53 controlled checkpoint in regulating autophagy and receptor degradation

Area of Science:

• Cellular biology
• Molecular mechanisms of DNA damage response
• Autophagy regulation

Background:

• Vacuolar protein-sorting 34 (Vps34) is crucial for phosphatidylinositol 3-phosphate (PtdIns3P) production, regulating autophagy and receptor degradation.
• The signaling pathways controlling Vps34 activity and downstream effects in response to extracellular signals remain incompletely understood.

Purpose of the Study:

• To elucidate the molecular mechanisms by which DNA damage regulates Vps34 complexes.
• To identify the signaling pathways linking DNA damage to Vps34-mediated cellular processes like autophagy and receptor endocytosis.

Main Methods:

• Investigated the role of Vps34 phosphorylation in response to DNA damage-induced mitotic arrest and CDK activation.
• Utilized FBXL20 and Skp1-Cullin1 complex to study Vps34 ubiquitination and proteasomal degradation.
• Examined the transcriptional regulation of FBXL20 by p53.

Main Results:

• DNA damage-activated mitotic arrest and CDK activation induce Vps34 phosphorylation.
• Phosphorylated Vps34 is targeted for ubiquitination and proteasomal degradation by the FBXL20-SCF complex.
• FBXL20 expression is transcriptionally regulated by p53, linking p53 to Vps34 regulation.
• Inhibition of autophagy and receptor endocytosis occurs downstream of Vps34 degradation.

Conclusions:

• A novel molecular pathway is identified where DNA damage regulates Vps34 complexes via SCF-mediated ubiquitination and degradation.
• FBXL20 acts as a key mediator, linking p53-dependent transcription to Vps34 regulation.
• This pathway provides a new checkpoint for p53 in controlling autophagy and receptor degradation during the DNA damage response.