Screening with a Novel Cell-Based Assay for TAZ Activators Identifies a Compound That Enhances Myogenesis in C2C12 Cells and Facilitates Muscle Repair in a Muscle Injury Model

Abstract

The transcriptional coactivator with a PDZ-binding motif (TAZ) cooperates with various transcriptional factors and plays various roles. Immortalized human mammalian epithelial MCF10A cells form spheres when TAZ is overexpressed and activated. We developed a cell-based assay using sphere formation by TAZ-expressing MCF10A cells as a readout to screen 18,458 chemical compounds for TAZ activators. Fifty compounds were obtained, and 47 were confirmed to activate the TAZ-dependent TEAD-responsive reporter activity in HEK293 cells. We used the derived subset of compounds as a TAZ activator candidate minilibrary and searched for compounds that promote myogenesis in mouse C2C12 myoblast cells. In this study, we focused on one compound, IBS008738. IBS008738 stabilizes TAZ, increases the unphosphorylated TAZ level, enhances the association of MyoD with the myogenin promoter, upregulates MyoD-dependent gene transcription, and competes with myostatin in C2C12 cells. TAZ knockdown verifies that the effect of IBS008738 depends on endogenous TAZ in C2C12 cells. IBS008738 facilitates muscle repair in cardiotoxin-induced muscle injury and prevents dexamethasone-induced muscle atrophy. Thus, this cell-based assay is useful to identify TAZ activators with a variety of cellular outputs. Our findings also support the idea that TAZ is a potential therapeutic target for muscle atrophy.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://dx.doi.org/10.1128/MCB.01346-13.

ACKNOWLEDGMENTS

We are grateful for Hiroshi Asahara (Tokyo Medical and Dental University), Yasutomi Kamei (Kyoto Prefectural University), Hiroki Kurihara (The University of Tokyo), Yoshihiro Ogawa (Tokyo Medical and Dental University), Hiroshi Sasaki (Kumamoto University), Kenji Miyazawa (Yamanashi University), Kohei Miyazono (The University of Tokyo), Hiroshi Takayanagi (The University of Tokyo), and Sumiko Watanabe (The University of Tokyo) for materials and advice.

This work was supported by research grants from the Ministry of Education, Sports, Science, and Technology (17081008), the Japan Society for the Promotion of Science (22790275 and 22590267), the Suzuken Memorial Foundation, the Nakatomi Foundation, the Uehara Memorial Foundation, and the Naito Foundation. Z.Y. was supported by a Japanese Government (Monbukagakusho) (MEXT) scholarship.