Barsh G S, Roush C L, Gelinas R E
J Biol Chem. 1984 Dec 10;259(23):14906-13.
The human alpha 1 (I) collagen gene and 48 kilobase pairs of flanking DNA have been isolated on two overlapping cosmids. The alpha 1 (I) gene is 18 kilobase pairs long and contains a single repetitive element of the Alu family; at least 15 repetitive elements are present in the flanking DNA. Analysis of chromatin structure in nuclei isolated from cultured fibroblasts demonstrated a single chromatin domain greater than 65 kilobase pairs in length that contained 9 DNase I-hypersensitive sites. The pattern of hypersensitive sites was also determined in nuclei derived from placental tissue. Five of the DNase I-hypersensitive sites were observed in both placental and fibroblast chromatin including one site near the 5' end and another near the 3' end of alpha 1 (I). An additional two sites located near the 3' end of the alpha 1 (I) gene in fibroblast chromatin are associated with the tissue-specific use of different polyadenylation sites. Two DNase I-hypersensitive sites found only in fibroblast chromatin and one site found only in placental chromatin were located more than 10 kilobase pairs away from the alpha 1 (I) gene and may be related to tissue-specific expression of other genes in the domain. However, the only abundant placental mRNAs from the 65-kilobase pair domain were those transcribed from the alpha 1 (I) gene. These findings suggest that physical linkage does not play a predominant role in controlling coordinate expression of collagen genes.
人类α1（I）型胶原蛋白基因及48千碱基对的侧翼DNA已在两个重叠的黏粒上分离出来。α1（I）基因长18千碱基对，包含一个Alu家族的单一重复元件；侧翼DNA中至少存在15个重复元件。对从培养的成纤维细胞中分离出的细胞核中的染色质结构分析表明，存在一个长度大于65千碱基对的单一染色质结构域，其中包含9个对DNase I敏感的位点。还确定了来自胎盘组织的细胞核中敏感位点的模式。在胎盘和成纤维细胞染色质中均观察到5个对DNase I敏感的位点，其中一个位点靠近α1（I）的5'端，另一个靠近3'端。在成纤维细胞染色质中位于α1（I）基因3'端附近的另外两个位点与不同聚腺苷酸化位点的组织特异性使用有关。仅在成纤维细胞染色质中发现的两个对DNase I敏感的位点和仅在胎盘染色质中发现的一个位点距离α1（I）基因超过10千碱基对，可能与该结构域中其他基因的组织特异性表达有关。然而，来自65千碱基对结构域的唯一丰富的胎盘mRNA是那些从α1（I）基因转录而来的。这些发现表明，物理连接在控制胶原蛋白基因的协同表达中并不起主要作用。
