Here, we studied the subpopulation differentiation and function of Treg cells in the myocardium of DCM and explored the role of DBC1 in Treg cell differentiation.<h4>Methods</h4>DBC1<sup>fl/fl</sup>, DBC1<sup>fl/fl</sup>-Fxop3<sup>Cre</sup>, HIF-1α<sup>fl/fl</sup>-Fxop3<sup>Cre</sup>, PPAR-γ<sup>fl/fl</sup>-Fxop3<sup>Cre</sup> DCM mouse models were established to evaluate the effects of DBC, HIF-1α, and PPAR-γ on cardiac fibrosis and function. The gene discussed is CCAR2; the disease is familial dilated cardiomyopathy.