title: Absence of AMPKα2 accelerates cellular senescence via p16 induction in mouse embryonic fibroblasts.
abstract: Emerging evidence suggests that activation of adenosine monophosphate-activated protein kinase (AMPK), an energy gauge and redox sensor, delays aging process. However, the molecular mechanisms by which AMPKα isoform regulates cellular senescence remain largely unknown. The aim of this study was to determine if AMPKα deletion contributes to the accelerated cell senescence by inducing p16(INK4A) (p16) expression thereby arresting cell cycle. The markers of cellular senescence, cell cycle proteins, and reactive oxygen species (ROS) were monitored in cultured mouse embryonic fibroblasts (MEFs) isolated from wild type (WT, C57BL/6J), AMPKα1, or AMPKα2 homozygous deficient (AMPKα1(-/-), AMPKα2(-/-)) mice by Western blot and cellular immunofluorescence staining, as well as immunohistochemistry (IHC) in skin tissue of young and aged mice. Deletion of AMPKα2, the minor isoform of AMPKα, but not AMPKα1 in high-passaged MEFs led to spontaneous cell senescence demonstrated by accumulation of senescence-associated-β-galactosidase (SA-β-gal) staining and foci formation of heterochromatin protein 1 homolog gamma (HP1γ). It was shown here that AMPKα2 deletion upregulates cyclin-dependent kinase (CDK) inhibitor, p16, which arrests cell cycle. Furthermore, AMPKα2 null cells exhibited elevated ROS production. Interestingly, knockdown of HMG box-containing protein 1 (HBP1) partially blocked the cellular senescence of AMPKα2-deleted MEFs via the reduction of p16. Finally, dermal cells senescence, including fibroblasts senescence evidenced by the staining of p16, HBP1, and Ki-67, in the skin of aged AMPKα2(-/-) mice was enhanced when compared with that in wild type mice. Taken together, our results suggest that AMPKα2 isoform plays a fundamental role in anti-oxidant stress and anti-senescence.
authors.affiliation: Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30303, USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30303, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.affiliation: Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30303, USA.
authors.forename: Imoh Sunday
authors.initials: IS
authors.lastname: Okon
authors.affiliation: Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30303, USA.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Zou
authors.affiliation: Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA 30303, USA. Electronic address: psong@gsu.edu.
authors.forename: Ping
authors.initials: P
authors.lastname: Song
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D016922:Cellular Senescence; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D004622:Embryo, Mammalian / Q000166:cytology*; D005347:Fibroblasts / Q000166:cytology*; D017353:Gene Deletion; D006609:High Mobility Group Proteins / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D017382:Reactive Oxygen Species / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D012867:Skin / Q000166:cytology; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D019941:Cyclin-Dependent Kinase Inhibitor p16; C486329:Hbp1 protein, mouse; D006609:High Mobility Group Proteins; D017382:Reactive Oxygen Species; D012097:Repressor Proteins; C534978:Prkaa2 protein, mouse; D055372:AMP-Activated Protein Kinases
keywords: AMPKα2; Cellular senescence; HBP1; Reactive oxygen species; p16