TRPC (transient receptor potential canonical) genes have been implicated in the development of muscular dystrophy.
These transgenic animals overexpress human transient receptor potential canonical 3 (TRPC3) cDNA driven by a modified human ACTA1 (actin, alpha 1, skeletal muscle) promoter. A 6-fold increase in expression can be seen in skeletal muscle, but not other organs or tissues. Immunohistochemistry from the quadriceps confirms that the overexpressed protein is appropriately localized to the sarcolemma. An increase in calcium influx results in a phenotype similar to dystrophin-glycoprotein complex (DGC)-lacking dystrophic disease. Transgenic animals show profound wasting of all skeletal muscles examined at 2 months of age, as determined by direct measurement of muscle weights. Histological analysis of the muscles reveals increased central nucleation of fibers (due to degeneration/regeneration cycles), increased numbers of small myofibers, fibrosis, and infiltration of inflammatory cells. Disease progresses and by 6 months of age, fatty tissue replacement can be seen throughout muscle, along with increased fibrosis and greater variations in fiber area distributions with prominent macrophage infiltration. The heart is unaffected.
