Impact and mechanism of the TBX-22 gene mutation G874A on the epithelial-mesenchymal transition in medial edge epithelial cells.

Cleft lip and palate (CL/P) are prevalent congenital anomalies with complex genetic causes. The G874A mutation of T-box transcription factor 22 (TBX-22) gene is notably associated with CL/P, while the underlying mechanism remains to be clarified. Studies have shown that the restriction of epithelial-mesenchymal transformation (EMT) process in medial edge epithelial cells (MEEs) is crucial for CL/P development. In our current research, primary MEEs, isolated and cultured from mouse embryos, were genetically introduced the TBX-22 G874A mutation and subsequently treated with TGF-β1. They were then utilized to test the hypothesis that the G874A mutation in TBX22 plays a role in the regulation of the EMT in MEEs. Our findings reveal that TBX22 reduces miR140-5p transcription by binding to its promoter, while miR140-5p downregulates TGFBR1 protein expression by targeting its mRNA 3'-UTR. In other words, TBX22 could indirectly positively regulates TGFBR1 expression post-transcriptionally. Functional cellular assays showed that the G874A mutation of TBX-22 counteracted TGF-β1-induced decrease in proliferation and migration. Western blotting results showed that the G874A mutation of TBX-22 inhibited EMT protein expression (α-SMA and Vimentin) and promoted E-cadherin in TGF-β1-induced MEEs. To summarize, our research reveals that the G874A mutation of TBX22 impedes the progression of EMT in MEEs through the upregulation of miR140-5p and the downregulation of TGFBR1. This highlights TGFBR1 as a viable target for the prevention of CL/P.