SPERMATID-SPECIFIC OVEREXPRESSION OF THE TATA-BINDING PROTEIN GENE INVOLVES RECRUITMENT OF 2 POTENT TESTIS-SPECIFIC PROMOTERS

Citation
Ee. Schmidt et al., SPERMATID-SPECIFIC OVEREXPRESSION OF THE TATA-BINDING PROTEIN GENE INVOLVES RECRUITMENT OF 2 POTENT TESTIS-SPECIFIC PROMOTERS, The Journal of biological chemistry, 272(8), 1997, pp. 5326-5334
Citations number
25
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology
ISSN journal
0021-9258
Volume
272
Issue
8
Year of publication
1997
Pages
5326 - 5334
Database
ISI
SICI code
0021-9258(1997)272:8<5326:SOOTTP>2.0.ZU;2-2
Abstract
The gene encoding the TATA-binding protein, TBP, is highly overexpress ed during the haploid stages of spermatogenesis in rodents, RNase prot ection analyses for mRNAs containing the previously identified first, second, and eighth exons suggested that most TBP mRNAs in testis did n ot initiate at the first exon used in somatic cells (here designated e xon 1C), Using a sensitive ligation-mediated cDNA amplification method , 5' end variants of TBP mRNA were identified, and the corresponding c DNAs were cloned from liver and testis, In liver, a single promoter/fi rst exon is used to generate a steady-state level of roughly five mole cules of TBP mRNA per diploid cell equivalent. In testis, we detect mo dest up-regulation of the somatic promoter and recruitment of at least five other promoters, Three of the alternative promoter/first exons, including 1C and two of the testis-specific promoter/first exons, 1D a nd 1E, contribute roughly equivalent amounts of mRNA which, in sum, ac count for greater than 90% of all TBP mRNA in testis. As a result, rou nd spermatids contain an estimated 1000 TBP mRNA molecules per haploid cell, Testis TBP mRNA also exhibits several low abundance 5' end spli cing variants; however, all detected TBP mRNA leader sequences splice onto the common exon 2 and are expected to initiate translation at the same site within exon 2, The precise locations of the three major ini tiation exons are mapped on the gene, The identification of the strong testis specific promoter/first exons will be important for understand ing spermatid-specific tbp gene regulation.