Expression of a novel HsMCAK mRNA splice variant, tsMCAK gene, in human testis

Identification of specifically expressed genes in the adult or fetal testis is very important for the study of genes related to the development and function of the testis. In this study, a human adult testis cDNA microarray was constructed and hybridized with 33P-labeled human adult and embryo testis cDNA probes, respectively. After differential display analyzing, a number of new genes related to the development of testis and spermatogenesis had been identified. One of these new genes is tsMCAK. tsMCAK was expressed 2.62 folds more in human adult testis than fetal testis. The full length of tsMCAK is 2401 bp and contains a 2013 bp open reading frame, encoding a 671-amino-acid protein. Sequence analysis showed that it has a central kinesin motor domain and is homologous to HsMCAK gene of the somatic cells. Blasting human genome database localized tsMCAK to human chromosome 1P34 and further investigation showed that it is a splice variant of HsMCAK. The tissue distribution of tsMCAK was determined by RT-PCR and it is expressed highly and specifically in the testis. Southern blot studies of its expression in patients with infertility indicated its specific expression in spermatogenic cells and its correlation with male infertility. The above results suggested that tsMCAK is a candidate gene for the testis-specific KRPs and its specific expression in the testis was correlated with spermatogenesis and may be correlated with male infertility.