title: Bax-/- bak-/- cells exhibit p27 Thr198 phosphorylation and autophagy.
abstract: Cell cycle arrest in G(0) and autophagy share features in common. The Bcl-2 family exerts cell cycle effects in addition to regulating apoptosis. Bcl-2 and Bcl-x(L) upregulate p27 and promote G(0) arrest. Recently, we asked whether autophagy was involved in Bcl-2 and Bcl-x(L)-mediated cell cycle arrest, and found that autophagy was activated, but not required, for G(0) arrest. We also discovered that the cell cycle function of Bcl-2 and Bcl-x(L) was dependent on Bax and Bak, and in bax(-/-) bak(-/-) double knockout cells, features of G(0) quiesecence were already present and p27 was constitutively elevated. Here, we queried the presence of autophagy in bax(-/-) bak(-/-) double knockout cells, and report the phosphorylation of p27 at Thr198, which is known to occur in autophagy, as well as constitutive Atg5 induction and LC3-I to -II conversion. These findings in bax(-/-) bak(-/-) cells suggest that a physiological role of Bax and Bak may be the suppression of autophagy.
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Cui
authors.forename: Mayda
authors.initials: M
authors.lastname: Valentin
authors.forename: Yelena
authors.initials: Y
authors.lastname: Janumyan
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Yang
mesh_terms: D000818:Animals; D001343:Autophagy; D015153:Blotting, Western; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D010766:Phosphorylation; D010769:Phosphothreonine / Q000378:metabolism*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000172:deficiency* / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000172:deficiency* / Q000378:metabolism
chemical_list: D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D010769:Phosphothreonine; D050760:Cyclin-Dependent Kinase Inhibitor p27