Fig. 4. TGFβsecretion and bioavailability are tightly regulated.
Secretion and activity of TGFβ are tightly regulated. In a basal state, TGFβ is bound to the LTBPs and kept inactive in the extracellular matrix. Upon muscle injury TGFβ is activated and elicits downstream SMAD signaling, to repair the injury and restore muscle function. Dystrophic muscle is characterized by elevated TGFβ activity, which exacerbates the inflammatory response and aggravates the fibrotic response.