Effects of TGFBR1 on Proliferation of Dermal Papilla Cells in Fine-Wool Sheep

Dermal papilla cells (DPCs) serve as the signaling hub regulating hair follicle (HF) development and cyclical growth. This study aims to investigate the biological function and molecular mechanisms of TGFBR1 (transforming growth factor β receptor 1), a differentially expressed gene identified through single-cell transcriptomic sequencing (scRNA-seq) in the DPCs from fine-wool sheep. Primary DPCs were isolated and purified using a combination of enzymatic digestion and mechanical dissociation, followed by immunofluorescence identification (α-SMA and SOX2-positive). Following successful transfection with constructed TGFBR1 overexpression plasmids and siRNA interference vectors, cell proliferation was assessed via EDU staining and CCK-8 assays. mRNA expression of key genes in Wnt/β-catenin, BMP, and Notch signaling pathways (PCNA, CCND1, CTNNB1, SFRP2, BMP2, NOTCH3, SMAD4, etc.) was validated by RT-qPCR. Single-cell transcriptomics revealed significant downregulation of TGFBR1 in DPCs from fine-wool sheep. Functional validation demonstrated that TGFBR1 overexpression markedly suppressed DPC proliferation, whereas knockdown of TGFBR1 expression promoted DPC proliferation. Molecular mechanism studies showed that TGFBR1 overexpression significantly downregulated PCNA, CCND1, CTNNB1, NOTCH3, and SMAD4 while upregulating SFRP2, BMP2, and TGFB1 expression. These findings demonstrate that TGFBR1 acts as a negative regulator of DPCs proliferation by modulating the activity of multiple signaling pathways, including Wnt/β-catenin, BMP, and Notch, thereby suppressing the proliferative capacity of DPCs. This study not only provides new theoretical support for elucidating the role of the TGF-β signaling pathway in H development but also offers theoretical reference for in-depth research on molecular breeding in ultra -fine-wool sheep and the molecular mechanisms underlying HF development.