HOXA10直接调控人子宫内膜间质细胞中p/CAF启动子的活性

目的：筛选与鉴定转录因子同源框蛋白（HOX）A10下游靶基因。方法：用Ad-HOXA10重组腺病毒感染人子宫内膜间质细胞,通过染色体免疫共沉淀（ChIP）方法,筛选HOXA10的下游靶基因;采用萤光素酶报告基因实验结合腺病毒介导的HOXA10过表达和小干扰RNA介导的基因沉默实验,分析HOXA10对下游靶基因的转录调控作用。结果：ChIP-PCR筛选并鉴定p/CAF（p300/CBP相关因子）为HOXA10直接作用的靶基因;过表达HOXA10抑制p/CAF启动子活性达60%;基因沉默内源性HOXA10的表达可以激活p/CAF启动子活性超过2倍以上。结论：p/CAF是HOXA10新的靶基因,HOXA10可能通过调节p/CAF的表达来调控子宫内膜的发育。     

Isolation of the human MOX2 homeobox gene and localization to chromosome 7p22.1–p21.3

We have isolated and characterized cDNA clones encoding a novel human homeobox gene, MOX2, the homologue of the murine mox-2 gene. The MOX2 protein contains all of the characteristic features of Mox-2 proteins of other vertebrate species, namely the homeobox, the polyhistidine stretch, and a number of potential serine/threonine phosphorylation sites. The homeodomain of MOX2 protein is identical to all other vertebrate species reported so far (rodents and amphibians). Outside the homeodomain, Mox-2 proteins share a high degree of identity, except for a few amino acid differences encountered between the human and the rodent polypeptides. A polyhistidine stretch of 12 amino acids in the N terminal region of the protein is also conserved among humans, rodents, and (only partly) amphibians. The chromosomal position of MOX2 was assigned to 7p22.1–p21.3.     

A novel class of plant proteins containing a homeodomain with a closely linked leucine zipper motif.

The homeobox, a 183 bp DNA sequence element, was originally identified as a region of sequence similarity between many Drosophila homeotic genes. The homeobox codes for a DNA-binding motif known as the homeodomain. Homeobox genes have been found in many animal species, including sea urchins, nematodes, frogs, mice and humans. To isolate homeobox-containing sequences from the plant Arabidopsis thaliana, a cDNA library was screened with a highly degenerate oligonucleotide corresponding to a conserved eight amino acid sequence from the helix-3 region of the homeodomain. Using this strategy two cDNA clones sharing homeobox-related sequences were identified. Interestingly, both of the cDNAs also contain a second element that potentially codes for a leucine zipper motif which is located immediately 3'' to the homeobox. The close proximity of these two domains suggests that the homeodomain-leucine zipper motif could, via dimerization of the leucine zippers, recognize dyad-symmetrical DNA sequences.     

Nucleotides flanking a conserved TAAT core dictate the DNA binding specificity of three murine homeodomain proteins.

Murine homeobox genes play a fundamental role in directing embryogenesis by controlling gene expression during development. The homeobox encodes a DNA binding domain (the homeodomain) which presumably mediates interactions of homeodomain proteins with specific DNA sites in the control regions of target genes. However, the bases for these selective DNA-protein interactions are not well defined. In this report, we have characterized the DNA binding specificities of three murine homeodomain proteins, Hox 7.1, Hox 1.5, and En-1. We have identified optimal DNA binding sites for each of these proteins by using a random oligonucleotide selection strategy. Comparison of the sequences of the selected binding sites predicted a common consensus site that contained the motif (C/G)TAATTG. The TAAT core was essential for DNA binding activity, and the nucleotides flanking this core directed binding specificity. Whereas variations in the nucleotides flanking the 5' side of the TAAT core produced modest alterations in binding activity for all three proteins, perturbations of the nucleotides directly 3' of the core distinguished the binding specificity of Hox 1.5 from those of Hox 7.1 and En-1. These differences in binding activity reflected differences in the dissociation rates rather than the equilibrium constants of the protein-DNA complexes. Differences in DNA binding specificities observed in vitro may contribute to selective interactions of homeodomain proteins with potential binding sites in the control regions of target genes.     

The freshwater planarian Dugesia (G.) tigrina contains a great diversity of homeobox genes

To identify potential pattern control and cell determination and/or differentiation genes in the freshwater planarian Dugesial (G.) tigrina, we searched for homeobox genes of different types in the genome of this primitive metazoan. We applied two basic approaches: 1) Screening the cDNA library with degenerate oligonucleotides corresponding to the most conserved amino acid sequence from helix-3 of the homeodomain of each family; and 2) PCR amplification of genomic DNA or cDNA, using two sets of degenerated oligonucleotides corresponding to helices 1 and 3 of the homeodomain or two specific domains of the POU family. Using the first strategy we have identified and characterized two tissue-specific cell determination and/or differentiation NK-type homeobox genes. Using the second strategy we have identified several homeobox genes that belong to the HOM/Hox, paired (prd) or POU families.