Novel leader exons of the cyclic adenosine 3',5'-monophosphate response element modulator (CREM) gene, transcribed from promoters P3 and P4, are highly testis-specific in primates.
Testicular expression of CREM is essential for spermatogenesis in the mouse. From a monkey testis cDNA library we isolated a CREM transcript isoform with a novel 5' exon theta2 which provides at its 3'-end an in-frame ATG to the downstream reading frame. 5'-RACE on human testis cDNA indicated that exon theta2 is > or = 113 bp in size. Moreover, a second novel leader exon, theta1, of > or = 289 bp was identified and encodes a putative open reading frame of 26 amino acids. In-vitro translation and cellular expression of CREM-theta1 and CREM-theta2 splice variants cloned from human testis yielded not only full length proteins but also shorter repressor products resulting from downstream translation initiation. Upon co-transfection, products of CREM-theta2 cDNA repressed protein kinase A-induced activation of a CRE-driven reporter construct. RT-PCR analysis of primate tissues for CREM-theta2 transcripts showed abundant expression in the testis and very low levels or absence from all other tissues tested. CREM-theta1 mRNA was exclusively expressed in the testis. Promoters P3 and P4, flanking exons theta1 and theta2, were cloned and found to be non-responsive to protein kinase A in transfection assays. Furthermore, we show differential activation of P1, P3 and P4 during mouse postnatal testicular development, suggesting cell- and stage-specific regulatory mechanisms for these CREM promoters.
Gellersen
Birgit
B
IHF Institute for Hormone and Fertility Research, University of Hamburg, D-22529 Hamburg, Germany.
Kempf
Rita
R
Sandhowe
Reinhild
R
Weinbauer
Gerhard F
GF
Behr
Rüdiger
R
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051786:Cyclic AMP Response Element Modulator; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005091:Exons; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008252:Macaca fascicularis / Q000235:genetics; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity; D011323:Primates / Q000235:genetics*; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D013091:Spermatogenesis / Q000235:genetics; D013737:Testis / Q000502:physiology*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D020033:Protein Isoforms; D012097:Repressor Proteins; D051786:Cyclic AMP Response Element Modulator; D017868:Cyclic AMP-Dependent Protein Kinases