伴性矮小型鸡GH、GHR和IGF-1基因的表达变化

Expression profiling of GH,GHR,and IGF-1 genes in sex-linked dwarf chickens

采用荧光实时定量PCR的方法,从转录水平上分析了伴性矮小型鸡和普通鸡肝脏中GH、GHR和IGF-1基因的表达变化趋势。结果表明:伴性矮小型鸡和普通鸡肝脏组织中GH的mRNA表达量没有明显差异,而GHR在矮小鸡中的表达量明显比普通鸡的高3倍多,但IGF-1基因在矮小鸡肝脏中的表达量却远远低于普通鸡,差异达到2个数量级。这表明,伴性矮小型鸡GHR外显子10和3′非翻译区的长片断缺失并没有降低GHR基因的表达,相反有所增高,这一过程中可能存在相应的功能代偿机制。与此同时,在伴性矮小型鸡肝脏中几乎观察不到IGF-1基因的表达,证明正是由于GHR基因的缺陷影响了GH生理效应的发挥。实验结果印证了伴性矮小表型与GH和GHR的转录水平无关,而可能是GHR编码产物异常阻碍了GH-GHR-IGF信号通路,导致IGF-1表达受阻,不能发挥正常的生理功能。

In this study, quantitative real-time PCR was used to compare the mRNA expression of GH, GHR, and IGF-1 genes in livers of sex-linked dwarf chickens with their normal siblings. The results showed that there was no significant difference between dwarf and normal chickens in GH expression. The expression of GHR gene was more than 3-fold higher in dwarf chickens, compared with that of the normal. However, the transcription level of IGF-1 decreased dramatically in the sex-linked dwarf. These observations suggest that the dwarf phenotype occurs independent of GH action, but is due to a dysfunctional GHR. A 1.7 kb deletion has been reported in exon 10 and the 3′untranslated region （UTR） of the GHR gene in dwarf chickens. This transcript could be translated into a protein that does not retain its normal function, which would account for the absence of GH-binding activity in liver membranes of the dwarf chickens.