Davenport E A, Nettesheim P
Laboratory of Pulmonary Pathobiology, Airway Cell Biology Group, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
Exp Cell Res. 1996 Feb 25;223(1):155-62. doi: 10.1006/excr.1996.0069.
Extracellular matrix (ECM) molecules, including those present in basement membranes, are known to play an important role in morphogenesis and differentiation. Primary rat tracheal epithelial (RTE) cells grown on permeable membranes in air-liquid interface (ALI) cultures differentiate into mucous and ciliated cells. We previously showed that RTE cell differentiation is accelerated and enhanced on type I collagen gel-coated membranes. The purpose of this study was to determine whether type I collagen gel matrix also regulates basement membrane formation by RTE cells and whether this correlates with differentiation. Therefore, we examined the synthesis and deposition of several ECM molecules by RTE cells maintained on uncoated and type I collagen gel-coated permeable membranes in ALI cultures. Fibronectin, thrombospondin-1, and alpha-1 type IV collagen gene expression were down-regulated in cultures maintained on type I collagen gel-coated membranes and in differentiated cultures. Fibronectin and laminin alpha, beta, and gamma protein levels also were decreased slightly in response to type I collagen gel and differentiation. Deposition of fibronectin and laminin were dependent on type I collagen gel substratum. While fibronectin and laminin deposition were evident underlying both undifferentiated and differentiated cultures on type I collagen gel, deposition of these proteins on uncoated membranes was not readily detectable in undifferentiated cultures and was limited to patches of fibronectin deposition beneath differentiated cultures. Evidence suggestive of a discontinuous basal lamina-like structure was most apparent underlying differentiated cultures on type I collagen gel. These date demonstrate that ECM RNA and protein expression by RTE cells in ALI cultures are down-regulated by type I collagen gel whereas differentiation and ECM deposition are accelerated and enhanced on type I collagen gel.
细胞外基质（ECM）分子，包括基底膜中存在的那些分子，已知在形态发生和分化中起重要作用。在气液界面（ALI）培养中生长在可渗透膜上的原代大鼠气管上皮（RTE）细胞分化为黏液细胞和纤毛细胞。我们之前表明，在I型胶原凝胶包被的膜上，RTE细胞的分化会加速并增强。本研究的目的是确定I型胶原凝胶基质是否也调节RTE细胞的基底膜形成，以及这是否与分化相关。因此，我们检测了在ALI培养中维持在未包被和I型胶原凝胶包被的可渗透膜上的RTE细胞对几种ECM分子的合成和沉积情况。在I型胶原凝胶包被的膜上维持的培养物以及分化的培养物中，纤连蛋白、血小板反应蛋白-1和α-1 IV型胶原基因表达下调。纤连蛋白和层粘连蛋白α、β和γ的蛋白水平也因I型胶原凝胶和分化而略有下降。纤连蛋白和层粘连蛋白的沉积依赖于I型胶原凝胶基质。虽然在I型胶原凝胶上未分化和分化的培养物下方都明显有纤连蛋白和层粘连蛋白的沉积，但在未分化培养物中，这些蛋白在未包被膜上的沉积不易检测到，且仅限于分化培养物下方的纤连蛋白沉积斑块。在I型胶原凝胶上分化的培养物下方，最明显的是存在暗示不连续基底膜样结构的证据。这些数据表明，在ALI培养中，I型胶原凝胶会下调RTE细胞的ECM RNA和蛋白表达，而在I型胶原凝胶上，分化和ECM沉积会加速并增强。
