E3 ubiquitin ligase, WWP1, interacts with AMPKα2 and down-regulates its expression in skeletal muscle C2C12 cells.

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.

Citation

Jung Ok Lee, Soo Kyung Lee, Nami Kim, Ji Hae Kim, Ga Young You, Ji Wook Moon, Sha Jie, Su Jin Kim, Yong Woo Lee, Ho Jin Kang, Yongchul Lim, Sun Hwa Park, Hyeon Soo Kim. E3 ubiquitin ligase, WWP1, interacts with AMPKα2 and down-regulates its expression in skeletal muscle C2C12 cells. The Journal of biological chemistry. 2013 Feb 15;288(7):4673-80

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PMID: 23293026

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