The destiny of the neural crest cells where the homeobox gene was ectopically expressed.

从人类基因组文库中分离出2号染色体上的人类同源盒基因HOXD3，并测定其核苷酸序列。为了研究HOXD3基因在红细胞生成中的作用，我们将含有HOXD3基因正反义取向的表达载体导入HEL细胞。过表达HOXD3基因的正义转染比反义转染和亲本HEL细胞更有效地附着在纤维连接蛋白和胶原上。Northern blot分析显示，在过表达HOXD3基因的HEL细胞中，整合素β 3 mRNA水平显著升高，而整合素β 1和alphaIIb mRNA水平与HOXD3 mRNA水平无明显相关性。荧光活化细胞分选分析显示，与亲本HEL细胞和反义转染相比，过表达HOXD3基因的义转染细胞表达的整合素alphaIIbbeta3 （GP IIbIIIa）复合物水平升高。此外，逆转录酶介导的聚合酶链反应（RT-PCR）分析显示，与义转染和亲本HEL细胞相比，在表达极低水平HOXD3 mRNA的反义转染细胞中，R-cadherin mRNA水平显著升高。这些结果提示同源盒基因HOXD3参与了细胞粘附过程的调控。为了验证HOXD3在小鼠胚胎发育中的调控作用，我制作了人类HOXD3基因在神经嵴细胞中特异性表达的转基因小鼠，并分析了细胞的分化和粘附性。

I isolated the human homeobox gene HOXD3 on chromosome 2 from a human genomic library and determined its nucleotide sequence. To study the role of HOXD3 gene in erythropoiesis, expression vectors containing the HOXD3 gene in the sense or antisense orientation were introduced into HEL cells. The sense transfectants overexpressing the HOXD3 gene attached more efficiently to fibronectin and collagen than did the antisense transfectants and parental HEL cells. Northern blot analysis showed that integrin beta3 mRNA levels were significantly increased in the HEL cells overexpressing the HOXD3 gene, whereas the integrin beta1 and alphaIIb mRNA levels did not show a distinct correlation with HOXD3 mRNA levels. Fluorescense-activated cell sorting analysis showed that the sense transfectants overexpressing the HOXD3 gene expressed increased levels of integrin alphaIIbbeta3 (GP IIbIIIa) complex as compared with the parental HEL cells and antisense transfectants. In addition, reverse transcriptase-mediated polymerase chain reaction (RT-PCR) analysis revealed that R-cadherin mRNA Ievels were significantly increased in the antisense transfectants expressing very low levels of the HOXD3 mRNA as compared to the sense transfectants and parental HEL cells. These results implicate the homeobox gene HOXD3 in the regulation of cell adhesion process. To verify the regulation by the HOXD3 also in developing mouse embryos, I made transgenic mice where the human HOXD3 gene was specifically expressed in the neural crest cells and analyzed the differentiation and adhessiveness of the cells.