Srivastava Jyoti, Premi Sanjay, Garg Lalit C, Ali Sher
Molecular Genetics Laboratory, National Institute of Immunology, New Delhi, India.
DNA Cell Biol. 2006 Sep;25(9):501-13. doi: 10.1089/dna.2006.25.501.
Protooncogene c-kit receptor is implicated with spermatogenesis, melanogenesis, and hematopoeisis, and undergoes tissue/stage specific alternate splicing. We have isolated 2973-bp full-length cDNA sequence (CDS) of this gene from testis and other tissues of water buffalo Bubalus bubalis. Upon comparison, the c-kit sequences showed tissue specific nucleotide changes resulting in novel truncated peptides. These peptides lacked intracellular and/or transmembrane domains in all the tissues except testis. Other alternately spliced tissue-specific transcripts were also detected, which are the integral parts of the open reading frame and have been reported in other mammals. Phylogenetic analysis of the sequences revealed unique tyrosine kinase domain in buffalo. Copy number calculation and expressional analysis of c-kit using real-time PCR established its single copy status and highest expression (137-177 folds) in testis compared to that (least) in liver. c-kit expression was detected in semen samples although 10 times lesser compared to that in testis. The highest expression of c-kit in testis and the presence of mRNA transcript in sperms substantiate its predominant role in spermatogenesis. This study establishes unequivocal involvement of an autosomal gene c-kit receptor in testicular function.
原癌基因c-kit受体与精子发生、黑色素生成和造血过程有关，并经历组织/阶段特异性可变剪接。我们从水牛（Bubalus bubalis）的睾丸和其他组织中分离出了该基因2973bp的全长cDNA序列（编码序列）。经比较，c-kit序列显示出组织特异性核苷酸变化，从而产生了新的截短肽。除睾丸外，这些肽在所有组织中均缺乏细胞内和/或跨膜结构域。还检测到了其他可变剪接的组织特异性转录本，它们是开放阅读框的组成部分，并且在其他哺乳动物中也有报道。对这些序列进行系统发育分析揭示了水牛中独特的酪氨酸激酶结构域。使用实时PCR对c-kit进行拷贝数计算和表达分析，确定其为单拷贝状态，并且在睾丸中的表达最高（是肝脏中表达量的137 - 177倍）（肝脏中表达量最少）。在精液样本中检测到了c-kit的表达，尽管其表达量比睾丸中的少10倍。c-kit在睾丸中的高表达以及精子中mRNA转录本的存在证实了其在精子发生中的主要作用。本研究明确证实了常染色体基因c-kit受体在睾丸功能中的作用。
