Beclin 1 Self-Association Is Independent of Autophagy Induction by Amino Acid Deprivation and Rapamycin Treatment

Autophagy, a process of self-digestion of cellular constituents, regulates the balance between protein synthesis and protein degradation Beclin 1 represents an important component of the autophagic machinery. It interacts with proteins that positively regulate autophagy, such as Vps34. UVRAG. and Ambra1, as well as with anti-apoptotic proteins such as Bcl-2 via its BH3-like domain to negatively regulate autophagy. Thus, Beclin 1 interactions with several proteins may regulate autophagy To identify novel Beclin 1 interacting proteins, we utilized a GST-Beclin 1 fusion protein. Using mass spectroscopic analysis, we identified Beclin 1 as a protein that interacts with GST-Beclin 1. Further examination by cross linking and co-immunoprecipitanon experiments confirmed that Beclin I self-interacts and that the coiled coil and the N-terminal region of Beclin 1 contribute toils oligomerization Importantly, overexpression of vps34, UVRAG, or Bck-x(1). had no effect on Beclin I self-interaction. Moreover, this self-interaction was independent of autophagy induction by amino acid deprivation or rapamycin treatment. These results suggest that full-length Beclin 1 is a stable ohgomer under various conditions Such an oligomer may provide a platform for further protein-protein interactions. J. Cell. Biochem 110. 1262-1271, 2010. (C) 2010 Wiley-Liss, Inc