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 <i>TGFBR1</i> (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 <i>TGFBR1</i> 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 (<i>PCNA</i>, <i>CCND1</i>, <i>CTNNB1</i>, <i>SFRP2</i>, <i>BMP2</i>, <i>NOTCH3</i>, <i>SMAD4</i>, etc.) was validated by RT-qPCR. Single-cell transcriptomics revealed significant downregulation of <i>TGFBR1</i> in DPCs from fine-wool sheep. Functional validation demonstrated that <i>TGFBR1</i> overexpression markedly suppressed DPC proliferation, whereas knockdown of <i>TGFBR1</i> expression promoted DPC proliferation. Molecular mechanism studies showed that <i>TGFBR1</i> overexpression significantly downregulated <i>PCNA</i>, <i>CCND1</i>, <i>CTNNB1</i>, <i>NOTCH3</i>, and <i>SMAD4</i> while upregulating <i>SFRP2</i>, <i>BMP2</i>, and <i>TGFB1</i> expression. These findings demonstrate that <i>TGFBR1</i> 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.