Jin Nili, Narasaraju Telugu, Kolliputi Narasaiah, Chen Jiwang, Liu Lin
Department of Physiological Sciences, Oklahoma State University, Stillwater, 74078, USA.
Cell Tissue Res. 2005 Aug;321(2):173-83. doi: 10.1007/s00441-005-1130-8. Epub 2005 May 24.
Although type A gamma-aminobutyric acid (GABA) receptors (ligand-gated Cl(-) channels) have been extensively studied in the central nervous system, no information is available on this receptor in lung cells. We have examined the expression of GABA(A) receptor pi-subunit (GABRP) during the trans-differentiation between rat alveolar epithelial type II cells and type I cells. Rat alveolar type II cells, when cultured on plastic plates, gradually trans-differentiated into type-I-like cells and lost their GABRP mRNA expression. However, the GABRP mRNA was partially retained in the type II cells cultured on Matrigel. Keratinocyte growth factor (a mitogen of type II cells) increased GABRP expression. A detached collagen gel maintained the GABRP mRNA to a level close to that of the freshly isolated type II cells. An air-liquid interface culture system, mimicking in vivo conditions in the lung, significantly up-regulated the expression of GABRP mRNA and protein. mRNAs of the GABA(A) receptor alpha1-, alpha3-, beta2-, gamma2-, and gamma3-subunits were also detected in rat type II cells. These results suggest that GABRP expression is differentially regulated by culture substrata, growth factor, detached gel, and an air-apical surface.
尽管A型γ-氨基丁酸（GABA）受体（配体门控性Cl(-)通道）已在中枢神经系统中得到广泛研究，但关于肺细胞中该受体的信息却尚无报道。我们研究了大鼠肺泡II型上皮细胞向I型细胞转分化过程中GABA(A)受体π亚基（GABRP）的表达情况。大鼠肺泡II型细胞在塑料培养板上培养时，会逐渐转分化为I型样细胞，并失去其GABRP mRNA表达。然而，在基质胶上培养的II型细胞中，GABRP mRNA会部分保留。角质形成细胞生长因子（II型细胞的一种促有丝分裂原）可增加GABRP表达。分离的胶原凝胶可将GABRP mRNA维持在接近新鲜分离的II型细胞的水平。模拟肺内体内条件的气液界面培养系统可显著上调GABRP mRNA和蛋白的表达。在大鼠II型细胞中也检测到了GABA(A)受体α1-、α3-、β2-、γ2-和γ3-亚基的mRNA。这些结果表明，GABRP的表达受到培养底物、生长因子、分离的凝胶和气-顶端表面的差异调节。
