MTOR kinase and the regulatory subunit of protein kinase A (PRKAR1A) Spatially and functionally interact during autophagosome maturation

Abstract

The regulatory subunit 1-alpha (RIα) of protein kinase A (PKA) and the mTOR kinase are involved in a common pathway regulating mammalian autophagy. RIα was found to localize on Rab7-positive late endosomes and on LC3-positive autophagosomal membranes in cultured cells. RIα was also shown to physically interact with mTOR kinase and affect its phosphorylation and activity. In this addendum, we further explore the subcellular distribution of mTOR related to RIα and LC3. We present experiments showing that mTOR colocalizes with RIα-, Rab7- and LC3-positive membranes in cultured cells. Because RIα regulates the phosphorylation and activity of mTOR kinase, which we now show localizes on autophagosomal membranes, the possibility emerges that the RIα-mTOR complex acts at the level of autophagosome maturation. ©2007 Landes Bioscience.