Functional analysis reveals that Tinagl1 is required for normal muscle development in mice through the activation of ERK signaling

Tinagl1 (tubulointerstitial nephritis antigen-like 1) is a matricellular protein involved in female infertility and breast cancer tumorigenesis. In this study, we analyzed the function of Tinagl1 in skeletal muscle using knockout mice and cell experiments. Although primary myoblasts isolated from Tinagl1 -decifient ( Tinagl1 −/− ) mice differentiated into normal myotubes, and treatment with recombinant Tinagl1 did not affect the proliferation or differentiation of C2C12 myoblasts, Tinagl1 −/− mice exhibited reduced body mass and calf muscle weights compared to the control group ( Tinagl1 flox/flox ). Furthermore, Tinagl1 −/− mice showed myofibers with centrally located nuclei, which is a morphological marker of regenerating muscle or myopathy. In addition, the capillary density in the soleus muscle of Tinagl1 −/− mice showed a decreasing trend compared to that of the control group. Importantly, si-RNA-mediated knockdown of TINAGL1 resulted in reduced tube formation in human umbilical vein endothelial cells (HUVECs), whereas treatment with Tinagl1 promoted tube formation. Immunoblot analysis revealed that Tinagl1 activates ERK signaling in both HUVECs and C2C12 myoblasts and myotubes, which are involved in the regulation of myogenic differentiation, proliferation, metabolism, and angiogenesis. Our results demonstrate that Tinagl1 may be required for normal muscle and capillary development through the activation of ERK signaling. • Tinagl1 deficiency in mice leads to reduced body and muscle weights and a myopathy-like phenotype. • Tinagl1 deficiency slightly reduced capillary density, but did not affect the fiber-type distribution of the soleus muscle in mice. • Tinagl1 treatment promoted tube formation of HUVECs, but did not affect myogenic differentiation and proliferation of C2C12 myoblasts. • Tinagl1 activates ERK signaling pathway in HUVECs and C2C12 cells.