绵羊ARHGAP36全长cDNA的克隆及其蛋白在睾丸精细管中的分布检测

Molecular cloning of the sheep ARHGAP36 full length cDNA and the protein distribution in seminiferous tubules

ARHGAP36是Rho GAPs家族的一员,在成神经管细胞瘤中超表达,可能参与调节细胞增殖。为了研究ARHGAP36在羊精子发生过程中的作用,采用RACE(rapid amplification of c DNA ends)技术从绵羊睾丸组织中克隆了SARHGAP36的c DNA全长序列。内部区域c DNA序列与5'RACE和3'RACE扩增的两端序列测序后拼接,得到了2698 bp的绵羊ARHGAP36 c DNA全长,其中包含一个长1593 bp的开放阅读框(ORF),编码530 aa,与Uni Prot中预测的牛ARHGAP36氨基酸序列(A7MB27)同源性为98%,说明我们克隆的c DNA是Rho GAP家族的成员ARHGAP36。对所克隆的绵羊ARHGAP36的氨基酸序列和Uni Prot数据库中所收集的所有其它ARHGAP成员的氨基酸序列比对分析显示,ARHGAP36没有其它ARHGAP成员都有的标志性"精氨酸指"基序,而它的对应基序中的保守精氨酸残基被苏氨酸替代了,暗示ARHGAP36很可能并不依靠酶催化活性发挥其功能。当把所克隆的c DNA与Gen Bank中发布的绵羊arhgap36序列比对时发现绵羊arhgap36基因组测序结果的第一个外显子中缺少一小段DNA,导致如果用该基因组序列预测绵羊ARHGAP36的c DNA,无法得到能编码正确氨基酸的c DNA,因此,实验为进一步研究ARHGAP36这个特殊ARHGAP成员的功能提供了正确的c DNA序列。绵羊睾丸总蛋白Western blot检测发现绵羊睾丸内的ARHGAP36有3种长度,免疫组织化学检测发现ARHGAP36蛋白在绵羊睾丸精细管中的精子发生过程中各类细胞中都有分布。

ARHGAP36, a member of Rho GAP（GTPase-activating proteins） family, is over expressed in medulloblastoma , and thus may be implicated in regulation of cell proliferation .To elucidate its function in sheep spermatogenesis , the full length cDNA of sheep ARHGAP36 was cloned using RACE （ rapid amplification of cDNA ends ） technique from sheep testicular tissue .A cDNA of 2698 bp was obtained after joining the 5′-and 3′RACE fragments with the middle region cloned and sequenced independently .An ORF （ open reading frame） of 1593 bp encoding a peptide of 530 aa with a homology of 98%with the predicted cattle ARHGAP36 （A7MB27） in the UniProt was found in this cDNA .Analysis of the all predicted amino acid sequence of ARHGAP 36 and other ARHGAP members from various animals collected in the UniProt showed that this ARHGAP 36 lacked the conserved arginine residue （ it is replaced with a threonine）in the ＂arginine finger＂, which was a hallmark motif of the Rho GAP family , suggesting the catalytic function may not be required for ARHGAP36.By aligning the cDNA to the predicted sheep Arhgap36 gene sequence （Gene ID：100913153） in GenBank, a criticalshort gap was also found in the first exon which will led to incapability of deducing a correct sheep ARHGAP 36 amino acid se-quence.Thus, the results provided a correct sheep ARHGAP 36 cDNA for the further research on the function of this unique Rho GAP family member .Detection of the total protein of sheep testis by Western blot and tissue sections of sheep testis by Immunohistochemis -try using anti-ARHGAP36 polyclonal antibody as the primary antibody indicated that ARHGAP 36 protein might have three forms of va-rious lengths in testis and exists in nearly all types of the cells during spermatogenesis in sheep seminiferous tubules .