An In Vitro Culture System for Long-Term Expansion of Epithelial and Mesenchymal Salivary Gland Cells: Role of TGF-1 in Salivary Gland Epithelial and Mesenchymal Differentiation
Figure 6
Confocal microscopy allows clear visualization of the differential protein expression of TGF-1 ligand and receptors in Col1a1-GFP derived submandibular salivary gland tissues and cultured cells. (a)–(c) Salivary gland epithelium, in particular ductal epithelium, strongly expressed TGF-1 (in cytoplasm) (a), TGF- receptor 1 (TGF-R1) (in nuclei and membrane) (b), and TGF- receptor 2 (TGF-R2) (in nuclei and membrane) (in red) (c). GFP-positive salivary gland mesenchyme (in green) did not seem to highly express either TGF-1 or TGF-R1 in normal salivary gland tissues. However, some GFP+ mesenchymal cells were strongly positive for membranous TGF-R2 staining in normal salivary gland tissues (c and inset). (d)–(f) Both cultured salivary gland epithelial and mesenchymal cells in late cultures (passage 9) showed the expression of TGF-1, TGF-R1, TGF-R2. The salivary gland mesenchymal cells increased the expression of TGF-1 (d), TGF-R1 (e, inset), and TGF-R2 (f) after late culture. The staining pattern of TGF-1 was seen in cytoplasm (d) whereas those of TGF-R1 and TGF-R2 were shown in both membrane and nuclei (e, inset, and f). AC = salivary gland acini, D = salivary gland duct. Scale bars = 50 μm.
