title: AMPKα1 deficiency promotes cellular proliferation and DNA damage via p21 reduction in mouse embryonic fibroblasts.
abstract: Emerging evidence suggests that activation of adenosine monophosphate-activated protein kinase (AMPK), an energy gauge and redox sensor, controls the cell cycle and protects against DNA damage. However, the molecular mechanisms by which AMPKα isoform regulates DNA damage remain largely unknown. The aim of this study was to determine if AMPKα deletion contributes to cellular hyperproliferation by reducing p21(WAF1/Cip1) (p21) expression thereby leading to accumulated DNA damage. The markers for DNA damage, cell cycle proteins, and apoptosis 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, flow cytometry, and cellular immunofluorescence staining. Deletion of AMPKα1, the predominant AMPKα isoform, but not AMPKα2 in immortalized MEFs led to spontaneous DNA double-strand breaks (DSB) which corresponded to repair protein p53-binding protein 1 (53BP1) foci formation and subsequent apoptosis. Furthermore, AMPKα1 localizes to chromatin and AMPKα1 deletion down-regulates cyclin-dependent kinase inhibitor, p21, an important protein that plays a role in decreasing the incidence of spontaneous DSB via inhibition of cell proliferation. In addition, AMPKα1 null cells exhibited enhanced cell proliferation. Finally, p21 overexpression partially blocked the cellular hyperproliferation of AMPKα1-deleted MEFs via the inhibition of cyclin-dependent kinase 2 (CDK2). Taken together, our results suggest that AMPKα1 plays a fundamental role in controlling the cell cycle thereby affecting DNA damage and cellular apoptosis.
authors.affiliation: Section of Molecular Medicine, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; School of Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China.
authors.forename: Hairong
authors.initials: H
authors.lastname: Xu
authors.affiliation: Section of Molecular Medicine, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Key Laboratory of Hubei Province on Cardio-Cerebral Diseases, Hubei University of Science and Technology, Xianning, Hubei, China.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Section of Molecular Medicine, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Coughlan
authors.affiliation: Section of Molecular Medicine, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Section of Molecular Medicine, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Shaobin
authors.initials: S
authors.lastname: Wang
authors.affiliation: Section of Molecular Medicine, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Section of Molecular Medicine, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA. Electronic address: ping-song@ouhsc.edu.
authors.forename: Ping
authors.initials: P
authors.lastname: Song
authors.affiliation: Section of Molecular Medicine, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Zou
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000502:physiology*; D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D002868:Chromosomal Proteins, Non-Histone / Q000502:physiology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000032:analysis / Q000502:physiology*; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000502:physiology; D005347:Fibroblasts / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: C493957:Cdkn1a protein, mouse; D002868:Chromosomal Proteins, Non-Histone; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; C498302:Trp53bp1 protein, mouse; D000071857:Tumor Suppressor p53-Binding Protein 1; C548179:Prkaa1 protein, mouse; C534978:Prkaa2 protein, mouse; D055372:AMP-Activated Protein Kinases
keywords: 53BP1; AMPKα; Apoptosis; Cell proliferation; DNA damage; p21