Troponin T3 regulates nuclear localization of the calcium channel Cav[beta]1a subunit in skeletal muscle

• Published in: Experimental cell research 2015-08, Vol.336 (2), p.276
• Main Authors: Zhang, Tan, Taylor, Jackson, Jiang, Yang, Pereyra, Andrea S, Messi, Maria Laura, Wang, Zhong-Min, Hereñú, Claudia, Delbono, Osvaldo
• Format: Article
• Language: English
• Subjects: Calcium; Musculoskeletal system; Proteins
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2015.05.005

The voltage-gated calcium channel (Cav) [beta]1a subunit (Cav[beta]1a) plays an important role in excitation-contraction coupling (ECC), a process in the myoplasm that leads to muscle-force generation. Recently, we discovered that the Cav[beta]1a subunit travels to the nucleus of skeletal muscle cells where it helps to regulate gene transcription. To determine how it travels to the nucleus, we performed a yeast two-hybrid screening of the mouse fast skeletal muscle cDNA library and identified an interaction with troponin T3 (TnT3), which we subsequently confirmed by co-immunoprecipitation and co-localization assays in mouse skeletal muscle in vivo and in cultured C2C12 muscle cells. Interacting domains were mapped to the leucine zipper domain in TnT3 COOH-terminus (160-244 aa) and Cav[beta]1a NH2-terminus (1-99 aa), respectively. The double fluorescence assay in C2C12 cells co-expressing TnT3/DsRed and Cav[beta]1a/YFP shows that TnT3 facilitates Cav[beta]1a nuclear recruitment, suggesting that the two proteins play a heretofore unknown role during early muscle differentiation in addition to their classical role in ECC regulation. * Previously, we demonstrated that Cav[beta]1a is a gene transcription regulator. * Here, we show that TnT3 interacts with Cav[beta]1a. * We mapped TnT3 and Cav[beta]1a interaction domain. * TnT3 facilitates Cav[beta]1a nuclear enrichment. * The two proteins play a heretofore unknown role during early muscle differentiation.