Stimulation of autophagy by the p53 target gene Sestrin2

Area of Science:

• Molecular Biology
• Cell Biology
• Oncology

Background:

• The tumor suppressor protein p53 plays a dual role in regulating autophagy.
• Cytoplasmic p53 inhibits autophagy independently of transcription, while nuclear p53 stimulates it via gene transactivation.

Purpose of the Study:

• To investigate the role of Sestrin2, a novel p53 target gene, in the regulation of autophagy.
• To determine if Sestrin2 functions as an autophagy inducer in p53-proficient cancer cells.

Main Methods:

• RNA interference (RNAi) was used to deplete Sestrin2 in human cancer cell lines.
• Gene knockout strategies were employed for Sestrin2 and Dram.
• Autophagy levels were measured in response to various inducers (nutrient depletion, rapamycin, lithium, thapsigargin).
• Sestrin2 expression was analyzed in p53-proficient and p53-deficient cells.

Main Results:

• Depletion of Sestrin2 significantly reduced autophagy induction in p53-sufficient cancer cells, comparable to Dram depletion.
• Knockout of Sestrin2 or Dram impaired autophagy induced by nutrient deprivation or pharmacological agents.
• Autophagy induction correlated with increased Sestrin2 expression in p53-proficient cells.
• Sestrin2 and Dram depletion did not affect autophagy in p53-deficient cells.

Conclusions:

• Sestrin2 is a novel p53 target gene that acts as a positive regulator of autophagy.
• The function of Sestrin2 in autophagy induction is dependent on the presence of functional p53.