PTEN is both an activator and a substrate of chaperone-mediated autophagy

PTEN is a lipid phosphatase that plays an important role in cancer and aging in mice. Zhang et al. show that PTEN regulates chaperone-mediated autophagy (CMA) and is itself a CMA substrate. Several metabolic changes downstream of PTEN require CMA activity. PTEN is a crucial negative regulator of the INS/PI3K/AKT pathway and is one of the most commonly mutated tumor suppressors in cancer. Global overexpression (OE) of PTEN in mice shifts metabolism to favor oxidative phosphorylation over glycolysis, reduces fat mass, and extends the lifespan of both sexes. We demonstrate that PTEN regulates chaperone-mediated autophagy (CMA). Using cultured cells and mouse models, we show that PTEN OE enhances CMA, dependent upon PTEN's lipid phosphatase activity and AKT inactivation. Reciprocally, PTEN knockdown reduces CMA, which can be rescued by inhibiting class I PI3K or AKT. Both PTEN and CMA are negative regulators of glycolysis and lipid droplet formation. We show that suppression of glycolysis and lipid droplet formation downstream of PTEN OE depends on CMA activity. Finally, we show that PTEN protein levels are sensitive to CMA and that PTEN accumulates in lysosomes with elevated CMA. Collectively, these data suggest that CMA is both an effector and a regulator of PTEN.

Automated summary

PTEN is a lipid phosphatase that plays a crucial role in cancer and aging. It regulates chaperone-mediated autophagy (CMA) and is a CMA substrate. Metabolic changes downstream of PTEN require CMA activity. Overexpression of PTEN enhances CMA, while PTEN knockdown reduces CMA. PTEN and CMA are both negative regulators of glycolysis and lipid droplet formation. The protein levels of PTEN are sensitive to CMA and accumulate in lysosomes with elevated CMA. CMA is both an effector and a regulator of PTEN.