Sawhney R S, Wood L S, Vogeli G
Department of Medicine, Medical College of Ohio, Toledo 43699, USA.
Cell Biol Int. 1997 Aug;21(8):501-10. doi: 10.1006/cbir.1997.0186.
This report is the first to describe the isolation of a 400 base pair cDNA clone encoding part of the bovine alpha 1(IV) procollagen. Using the polymerase chain reaction (PCR), we have amplified a sequence of approximately 400 bp from this gene within the recombinant phage DNA. The cloned sequence encodes 94 amino acids that form part of the protein's helical region. The sequence contains one interruption in the Gly-Xaa-Yaa repeat unit. The third base of the codon for glycine at several sites differs from those seen in murine and human genes, as does the third base of proline codons. The bovine cDNA also contains fewer thymine residues. Northern blot hybridization has shown that the mRNA for bovine procollagen to be 6.2 kb in size. We have used the cDNA clone to investigate the effect of all-trans retinoic acid (RA) on the gene expression of alpha 1(IV) procollagen in cultured bovine lens epithelial (LE) cells. We have also observed that RA decreases total protein production and concomitantly increases type IV procollagen in a concentration dependent manner. An increase in alpha 1(IV)mRNA as well as increase in type IV procollagen suggest that the regulation of alpha 1(IV) gene by RA in the LE cells is at the transcriptional level. Further, our results support the hypothesis that RA inhibition of lens epithelium transformation to fibroblast-like cells may be due to the ability of RA to stimulate the production of basement membrane components by epithelia.
本报告首次描述了编码牛α1(IV)前胶原部分序列的400个碱基对cDNA克隆的分离。利用聚合酶链反应(PCR)，我们从重组噬菌体DNA中的该基因扩增出了一段约400 bp的序列。克隆的序列编码94个氨基酸，这些氨基酸构成了该蛋白质螺旋区域的一部分。该序列在甘氨酸-Xaa-Yaa重复单元中有一个中断。几个位点的甘氨酸密码子的第三个碱基与小鼠和人类基因中的不同，脯氨酸密码子的第三个碱基也是如此。牛cDNA中的胸腺嘧啶残基也较少。Northern印迹杂交显示牛前胶原的mRNA大小为6.2 kb。我们利用该cDNA克隆研究了全反式视黄酸(RA)对培养的牛晶状体上皮(LE)细胞中α1(IV)前胶原基因表达的影响。我们还观察到RA以浓度依赖的方式降低总蛋白产量，并同时增加IV型前胶原。α1(IV)mRNA的增加以及IV型前胶原的增加表明RA在LE细胞中对α1(IV)基因的调节处于转录水平。此外，我们的结果支持这样的假说，即RA抑制晶状体上皮细胞向成纤维细胞样细胞的转化可能是由于RA刺激上皮细胞产生基底膜成分的能力。
