期刊
MOLECULAR REPRODUCTION AND DEVELOPMENT
卷 65, 期 2, 页码 148-156出版社
WILEY-LISS
DOI: 10.1002/mrd.10276
关键词
spermatid; spermatogenesis; retroposition; transgenic mouse
The Tact1 and Tact2 genes, each of which encodes an actin-like protein, are exclusively expressed and translated in haploid germ cells in testis. To characterize the haploid germ cell-specific gene structure, a mouse genomic library was screened with a Tact1 cDNA as a probe, and four independent phage clones containing the Tact1 gene were isolated. Southern hybridization and sequencing analyses revealed that Tact1 and Tact2 were single copy genes contained on a common fragment in a head-to-head orientation, and that the distance between these genes was less than 2 kb. Comparison of the nucleotide sequences of genomic. DNA and cDNA demonstrated that Tact1 and Tact2 lack introns, although all known actin or actin-related genes in mammals contain introns. Human Tact orthologues also lack introns and are located within 6.4 kb in a head-to-head orientation. These findings indicate that Tact1 and Tact2 or one of these genes arose by retroposition of a spliced mRNA transcribed from an actin progenitor gene prior to the divergence of rodents and primates. The Tact1 and Tact2 genes are unusual retroposons in that they have retained an open reading frame and are expressed in testicular germ cells, because almost all retroposons become pseudogenes. It was revealed that a 2kb sequence between the two genes bidirectionally controls haploid germ-cell specific expression by analyzing transgenic mice. Comparison of the murine Tact genes with their human orthologues showed a high level of identity between the two species in the 5'-upstream and non-coding sequences as well as in the coding region, indicating that conserved elements in these regions may be involved in the regulation of haploid germ cell-specific expression. The promoter region contains no TATA-, CCAAT- or GC-boxes, although there are potential cAMP response element (CRE)-like motifs in the 5'-upstream region and the 5'-untranslated region in Tact1 and Tact2, respectively. Transient promoter analyses indicate that CREMtau may activate Tact1 and Tact2 expression in germ cells. Mol. (C) 2003 Wiley-Liss, Inc.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据