title: E3 ubiquitin ligase, WWP1, interacts with AMPKα2 and down-regulates its expression in skeletal muscle C2C12 cells.
abstract: It is known that the activity of AMP-activated protein kinase (AMPKα2) was depressed under high glucose conditions. However, whether protein expression of AMPKα2 is also down-regulated or not remains unclear. In this study, we showed that the expression of AMPKα2 was down-regulated in cells cultured under high glucose conditions. Treatment of proteasome inhibitor, MG132, blocked high glucose-induced AMPKα2 down-regulation. Endogenous AMPKα2 ubiquitination was detected by immunoprecipitation of AMPKα2 followed by immunoblotting detection of ubiquitin. The yeast-two hybrid (YTH) approach identified WWP1, an E3 ubiquitin ligase, as the AMPKα2-interacting protein in skeletal muscle cells. Interaction between AMPKα2 and WWP1 was validated by co-immunoprecipitation. Knockdown of WWP1 blocked high glucose-induced AMPKα2 down-regulation. The overexpression of WWP1 down-regulated AMPKα2. In addition, the expression of WWP1 is increased under high glucose culture conditions in both mRNA and protein levels. The level of AMPKα2 was down-regulated in the quadriceps muscle of diabetic animal model db/db mice. Expression of WWP1 blocked metformin-induced glucose uptake. Taken together, our results demonstrated that WWP1 down-regulated AMPKα2 under high glucose culture conditions via the ubiquitin-proteasome pathway.
authors.affiliation: Department of Anatomy, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jung Ok
authors.initials: JO
authors.lastname: Lee
authors.forename: Soo Kyung
authors.initials: SK
authors.lastname: Lee
authors.forename: Nami
authors.initials: N
authors.lastname: Kim
authors.forename: Ji Hae
authors.initials: JH
authors.lastname: Kim
authors.forename: Ga Young
authors.initials: GY
authors.lastname: You
authors.forename: Ji Wook
authors.initials: JW
authors.lastname: Moon
authors.forename: Sha
authors.initials: S
authors.lastname: Jie
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Yong Woo
authors.initials: YW
authors.lastname: Lee
authors.forename: Ho Jin
authors.initials: HJ
authors.lastname: Kang
authors.forename: Yongchul
authors.initials: Y
authors.lastname: Lim
authors.forename: Sun Hwa
authors.initials: SH
authors.lastname: Park
authors.forename: Hyeon Soo
authors.initials: HS
authors.lastname: Kim
mesh_terms: D000818:Animals; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit / Q000378:metabolism*; D015536:Down-Regulation; D020868:Gene Silencing; D005947:Glucose / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit; C517819:PRKAR2A protein, human; C517821:Prkar2a protein, mouse; D012333:RNA, Messenger; D025801:Ubiquitin; C471642:WWP1 protein, human; C510836:WWP1 protein, mouse; D044767:Ubiquitin-Protein Ligases; D005982:Glutathione Transferase; D005947:Glucose