Testis-specific Expression Of The Nature And Function Of The Protein Spag8

The SPAG8 gene (named by HUGO Gene Nomenclature Committee, also know as HSD-1 gene) was isolated from the human testis cDNA expression library by using the antiserum of an infertile woman. The SPAG8 gene was a new gene and assigned the accession number U12978 by GeneBank. It was located on the 9th chromosome by using FISH assay. There were 7 exons and 6 introns in the SPAG8 gene. Sixteen different mRNAs from human tissues were analyzed by Northern blot, and evidence showed that the SPAG8 mRNA was only present in human testis. After transcription, the SPAG8 mRNA spliced alternatively at several sites, and formed various heterologous segments. The full-length segment encoded the SPAG8 protein with an estimated MW of 55 kD. Using yeast two-hybrid system with the C-terminal sequence of SPAG8 gene as bait to screen the human testis expression library, 3 potential interaction proteins with SPAG8 protein were obtained.In this paper, the character and function of SPAG8 protein had been studied basing on the previous works about SPAG8 protein.SPAG8 protein had been found expressed temporally and spatially. The SPAG8 protein was shuttling between cytoplasm and nucleus not only in CHO cells which express SPAG8 protein stably but also in germ cells. It could be exported from the nucleus into the cytoplasm through the nuclear pole complex with the help of CRM1 receptor. This nuclear export process could be inhibited by LMB, which bound covalently with CRM1 and inhibit the interaction between CRM1 and cargoes. The distribution of SPAG8 protein had been regulated by the development of germ cells. In spermatocyte cells the protein localized between nuclear and cytoplasm, while in sperm cells the protein was expressed exclusively only in acrosome and tail of the mouse sperm cells. One SPAG8 protein which was moving through the nuclear pore complex was captured by using scanning electron microscope. This result showed that the SPAG8 protein was indeed transport between nucleus and cytoplasm in detail.The expression pattern of SPAG8 gene was investigated by using RT-PCR assay...