title: A role of DNA-dependent protein kinase for the activation of AMP-activated protein kinase in response to glucose deprivation.
abstract: The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) plays an essential role in double-strand break repair by initially recognizing and binding to DNA breaks. Here, we show that DNA-PKcs interacts with the regulatory γ1 subunit of AMP-activated protein kinase (AMPK), a heterotrimeric enzyme that has been proposed to function as a "fuel gauge" to monitor changes in the energy status of cells and is controlled by the upstream kinases LKB1 and Ca²⁺/calmodulin-dependent kinase kinase (CaMKK). In co-immunoprecipitation analyses, DNA-PKcs and AMPKγ1 interacted physically in DNA-PKcs-proficient M059K cells but not in DNA-PKcs-deficient M059J cells. Glucose deprivation-stimulated phosphorylation of AMPKα on Thr172 and of acetyl-CoA carboxylase (ACC), a downstream target of AMPK, is substantially reduced in M059J cells compared with M059K cells. The inhibition or down-regulation of DNA-PKcs by the DNA-PKcs inhibitors, wortmannin and Nu7441, or by DNA-PKcs siRNA caused a marked reduction in AMPK phosphorylation, AMPK activity, and ACC phosphorylation in response to glucose depletion in M059K, WI38, and IMR90 cells. In addition, DNA-DNA-PKcs(-/-) mouse embryonic fibroblasts (MEFs) exhibited decreased AMPK activation in response to glucose-free conditions. Furthermore, the knockdown of DNA-PKcs led to the suppression of AMPK (Thr172) phosphorylation in LKB1-deficient HeLa cells under glucose deprivation. Taken together, these findings support the positive regulation of AMPK activation by DNA-PKcs under glucose-deprived conditions in mammalian cells.
authors.affiliation: DNA Damage Response Network Center, Chosun University School of Medicine, 375 Seosuk-dong, Gwangju 501-759, South Korea.
authors.forename: Parmeshwar Narayan
authors.initials: PN
authors.lastname: Amatya
authors.forename: Hong-Beum
authors.initials: HB
authors.lastname: Kim
authors.forename: Seon-Joo
authors.initials: SJ
authors.lastname: Park
authors.forename: Cha-Kyung
authors.initials: CK
authors.lastname: Youn
authors.forename: Jin-Won
authors.initials: JW
authors.lastname: Hyun
authors.forename: In-Youb
authors.initials: IY
authors.lastname: Chang
authors.forename: Jung-Hee
authors.initials: JH
authors.lastname: Lee
authors.forename: Ho Jin
authors.initials: HJ
authors.lastname: You
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004260:DNA Repair / Q000235:genetics; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005910:Glioma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005947:Glucose / Q000172:deficiency*; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency; D034741:RNA, Small Interfering / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: D004791:Enzyme Inhibitors; C526224:Prkag1 protein, mouse; D034741:RNA, Small Interfering; D051747:DNA-Activated Protein Kinase; C526222:PRKAG1 protein, human; D017346:Protein Serine-Threonine Kinases; C109790:STK11 protein, human; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; D005947:Glucose