Fibi M, Zink B, Kessel M, Colberg-Poley A M, Labeit S, Lehrach H, Gruss P
Max-Planck-Institut für biophysikalische Chemie, Göttingen, FRG.
Development. 1988 Feb;102(2):349-59. doi: 10.1242/dev.102.2.349.
We have characterized Hox 1.3 (previously described as m2), a murine homeobox-containing gene, which is a member of the Hox 1 cluster located on chromosome 6. A cloned cDNA was isolated from an Okayama-Berg library generated from the chemically transformed cell line MB66 MCA ACL6. The protein sequence of 270 amino acids was deduced from the nucleotide sequence of an open reading frame containing the homeobox. The open reading frame is interrupted at the genomic level by a 960 bp intron and is organized in two exons. The Hox 1.3 protein was found to contain extensive sequence homology with the murine homeodomain protein Hox 2.1, which is encoded on chromosome 11. There are two homology with the regions in the first exon, i.e. a hexapeptide conserved in many homeobox-containing genes and the N-terminal domain, which was found to be homologous only to Hox 2.1. Furthermore, in exon 2 the homologies of the homeodomain regions are extended up to the carboxy terminus of Hox 1.3 and Hox 2.1. During prenatal murine development, maximal expression of Hox 1.3 is observed in 12-day embryonic tissue. The two transcripts carrying the Hox 1.3 homeobox are 1.9 kb and about 4 kb in length. An abundant Hox 1.3-specific 1.9 kb RNA is also found in F9 cells which were induced for parietal endoderm differentiation, whereas F9 teratocarcinoma stem cells do not stably express this specific RNA. Induction of the transcript occurs immediately after retinoic acid/cAMP treatment and the RNA level remains high for 5 days. Thus, the kinetics are different from the previously described homeobox transcripts Hox 1.1 and Hox 3.1. Interestingly, by analogy to the F9 cell system a negative correlation between transformation and Hox 1.3 expression is observed in 3T3 fibroblasts also. Untransformed 3T3 cells carry abundant 1.9 kb Hox 1.3 RNA, whereas the methylcholanthrene-transformed MB66 and LTK- cells or 3T3 cells transformed by the oncogenes src, fos or SV40 T antigen express only low levels.
我们已经对Hox 1.3（先前称为m2）进行了特征描述，它是一个含小鼠同源异型框的基因，是位于6号染色体上的Hox 1基因簇的成员。从由化学转化细胞系MB66 MCA ACL6构建的冈山县-伯格文库中分离出一个克隆的cDNA。从包含同源异型框的开放阅读框的核苷酸序列推导得出270个氨基酸的蛋白质序列。该开放阅读框在基因组水平上被一个960 bp的内含子打断，并由两个外显子组成。发现Hox 1.3蛋白与在11号染色体上编码的小鼠同源结构域蛋白Hox 2.1具有广泛的序列同源性。在第一个外显子区域有两个同源性区域，即许多含同源异型框基因中保守的六肽和N端结构域，后者仅与Hox 2.1同源。此外，在外显子2中，同源结构域区域的同源性延伸至Hox 1.3和Hox 2.1的羧基末端。在小鼠产前发育过程中，在12天胚胎组织中观察到Hox 1.3的最大表达。携带Hox 1.3同源异型框的两种转录本长度分别为1.9 kb和约4 kb。在诱导为壁内胚层分化的F9细胞中也发现了丰富的Hox 特有的1.9 kb RNA，而F9畸胎瘤干细胞不稳定表达这种特异性RNA。转录本的诱导在视黄酸/cAMP处理后立即发生，并且RNA水平在5天内保持较高。因此，其动力学与先前描述的同源异型框转录本Hox 1.1和Hox 3.1不同。有趣的是，类似于F9细胞系统，在3T3成纤维细胞中也观察到转化与Hox 1.3表达之间呈负相关。未转化的3T3细胞携带丰富的1.9 kb Hox 1.3 RNA，而经甲基胆蒽转化的MB66和LTK - 细胞或由癌基因src、fos或SV40 T抗原转化的3T3细胞仅表达低水平。
