alpha1(I) collagen gene expression in quail epiphyseal chondrocytes

We examined alpha1(I) collagen expression by using primary cultures of quail epiphyseal chondrocytes which exhibit high levels of synthesis of cartilage-specific collagens and do not undergo phenotypic modulation when replated onto collagens I and II or fibronectin. These cells also synthesize proalpha1(I) collagen chain, however, alpha1(I) mRNA fails to be detected by Northern blot and RNase protection analysis. Nuclear transcription rate with a 5-end specific probe is detected in suspension quail chondrocytes and RT-PCR analysis shows the presence of low levels of alpha1(I) mRNA in these cells. The lack of correspondence between procollagen mRNA levels and the rate of collagen synthesis is consistent with previous reports describing the regulation of this transcript in chondrocytes and in collagen I-producing cells.