SFRP4 Knockdown Attenuates Dsg2-Deficient Arrhythmogenic Cardiomyopathy by Down-Regulating TGF-β and Smad3

Although secreted frizzled-related protein 4 (SFRP4) has been linked to the development of cardiovascular diseases; it is yet unknown how exactly it functions in arrhythmogenic cardiomyopathy (ACM) remains unclear. Data from the Gene Expression Omnibus (GEO) were used to identify genes that were differentially expressed and linked to ACM. A mouse model known as desmoglein 2 (Dsg2) knockout (Dsg2-/-) was employed to investigate ACM. Myocardial fibrosis was evaluated by histological analysis, while heart function was evaluated by echocardiography. Angiotensin II (Ang II) was used to stimulate cardiac fibroblasts (CFs) and cause a fibrotic phenotype. The ability of CFs to migrate was evaluate using a wound healing assay. Gene Set Enrichment Analysis (GSEA) was used to do an enrichment study of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. The levels of SFRP4, transforming growth factor beta receptor 2 (TGFBR2), TGF-beta 2, and Smad family member 3 (Smad3) were assessed using quantitative real-time PCR and Western blot. Our findings show that SFRP4 is highly expressed in Dsg2-/- mice. SFRP4 knockdown markedly reduced myocardial fibrosis, ventricular compliance, and cardiac dilation in Dsg2-/- mice. The level of SFRP4 was higher in CFs treated with Ang II, andSFRP4 inhibition markedly decreased the migration of Ang II-induced CFs. Moreover, SFRP4 activates the TGF-beta signaling pathway, with SFRP4 knockdown resulting in a significant decrease in the expression levels of TGF-beta 2, TGFBR2, and Smad3 in Dsg2-/- mice. In summary, SFRP4 knockdown reduced cardiac fibrosis in ACM by inhibiting the TGF-beta signaling pathway.