Novel TAZ modulators enhance myogenic differentiation and muscle regeneration.

Background And Purpose: The transcriptional co-activator with PDZ-binding motif (TAZ) is a key controller of mesenchymal stem cell differentiation through its nuclear localization and subsequent interaction with master transcription factors. In particular, TAZ directly associates with myoblast determining protein D (MyoD) and activates MyoD-induced myogenic gene expression, thereby enhancing myogenic differentiation. Here, we have synthesized and characterized low MW compounds modulating myogenic differentiation via induction of TAZ nuclear localization.

Experimental Approach: COS7 cells stably transfected with GFP-TAZ were used in a high content imaging screen for compounds specifically enhancing nuclear localization of TAZ. We then studied the effects of such TAZ modulators on myocyte differentiation of C2C12 cells and myogenic transdifferentiation of mouse embryonic fibroblast cells in vitro and muscle regeneration in vivo.

Key Results: We identified two TAZ modulators, TM-53, and its structural isomer, TM-54. Each compound strongly enhanced nuclear localization of TAZ by reducing S89-phosphorylation and dose-dependently augmented myogenic differentiation and MyoD-mediated myogenic transdifferentiation through an activation of MyoD-TAZ interaction. The myogenic stimulatory effects of TM-53 and TM-54 were impaired in the absence of TAZ, but retrieved by the restoration of TAZ. In addition, administration of TM-53 and TM-54 enhanced injury-induced muscle regeneration in vivo and attenuated myofiber injury in vitro.

Conclusions And Implications: The novel TAZ modulators TM-53 and TM-54 accelerated myogenic differentiation and improved muscle regeneration and function after injury, demonstrating that low MW compounds targeting the nuclear localization of TAZ have beneficial effects in skeletal muscle regeneration and in recovery from muscle degenerative diseases.