Dedigama-Arachchige Pavithra M, Acharige Nuwan P N, Zhang Xiangmin, Bremer Hannah J, Yi Zhengping, Pflum Mary Kay H
Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit 48202-3489, Michigan, United States.
Department of Pharmaceutical Sciences, Wayne State University, 259 Mack Ave, Detroit 48201, Michigan, United States.
ACS Omega. 2023 Sep 21;8(39):35628-35637. doi: 10.1021/acsomega.3c01944. eCollection 2023 Oct 3.
Protein phosphatase 1 regulatory subunit 12A (PPP1R12A) interacts with the catalytic subunit of protein phosphatase 1 (PP1c) to form the myosin phosphatase complex. In addition to a well-documented role in muscle contraction, the PP1c-PPP1R12A complex is associated with cytoskeleton organization, cell migration and adhesion, and insulin signaling. Despite the variety of biological functions, only a few substrates of the PP1c-PPP1R12A complex are characterized, which limit a full understanding of PP1c-PPP1R12A activities in muscle contraction and cytoskeleton regulation. Here, the chemoproteomics method Kinase-catalyzed Biotinylation to Identify Phosphatase Substrates (K-BIPS) was used to identify substrates of the PP1c-PPP1R12A complex in L6 skeletal muscle cells. K-BIPS enriched 136 candidate substrates with 14 high confidence hits. One high confidence hit, AKT1 kinase, was validated as a novel PP1c-PPP1R12A substrate. Given the previously documented role of AKT1 in PPP1R12A phosphorylation and cytoskeleton organization, the data suggest that PP1c-PPP1R12A regulates its own phosphatase activity through an AKT1-dependent feedback mechanism to influence cytoskeletal arrangement in muscle cells.
蛋白磷酸酶1调节亚基12A（PPP1R12A）与蛋白磷酸酶1（PP1c）的催化亚基相互作用，形成肌球蛋白磷酸酶复合物。除了在肌肉收缩中具有充分记录的作用外，PP1c-PPP1R12A复合物还与细胞骨架组织、细胞迁移和黏附以及胰岛素信号传导有关。尽管具有多种生物学功能，但PP1c-PPP1R12A复合物的底物只有少数得到了表征，这限制了对其在肌肉收缩和细胞骨架调节中活性的全面理解。在此，采用化学蛋白质组学方法激酶催化生物素化鉴定磷酸酶底物（K-BIPS）来鉴定L6骨骼肌细胞中PP1c-PPP1R12A复合物的底物。K-BIPS富集了136个候选底物，其中有14个高可信度命中蛋白。一个高可信度命中蛋白，即AKT1激酶，被验证为PP1c-PPP1R12A的新底物。鉴于先前记录的AKT1在PPP1R12A磷酸化和细胞骨架组织中的作用，这些数据表明PP1c-PPP1R12A通过一种依赖AKT1的反馈机制调节其自身的磷酸酶活性，从而影响肌肉细胞中的细胞骨架排列。
