title: Functional cooperation between CREM and GCNF directs gene expression in haploid male germ cells.
abstract: Cellular differentiation and development of germ cells critically depend on a coordinated activation and repression of specific genes. The underlying regulation mechanisms, however, still lack a lot of understanding. Here, we describe that both the testis-specific transcriptional activator CREMtau (cAMP response element modulator tau) and the repressor GCNF (germ cell nuclear factor) have an overlapping binding site which alone is sufficient to direct cell type-specific expression in vivo in a heterologous promoter context. Expression of the transgene driven by the CREM/GCNF site is detectable in spermatids, but not in any somatic tissue or at any other stages during germ cell differentiation. CREMtau acts as an activator of gene transcription whereas GCNF suppresses this activity. Both factors compete for binding to the same DNA response element. Effective binding of CREM and GCNF highly depends on composition and epigenetic modification of the binding site. We also discovered that CREM and GCNF bind to each other via their DNA binding domains, indicating a complex interaction between the two factors. There are several testis-specific target genes that are regulated by CREM and GCNF in a reciprocal manner, showing a similar activation pattern as during spermatogenesis. Our data indicate that a single common binding site for CREM and GCNF is sufficient to specifically direct gene transcription in a tissue-, cell type- and differentiation-specific manner.
authors.affiliation: Institut für Immunologie und Transfusionsmedizin, Ernst-Moritz-Arndt Universität, Greifswald, Germany.
authors.forename: Mirjana
authors.initials: M
authors.lastname: Rajkovic
authors.forename: K Alexander H
authors.initials: KA
authors.lastname: Iwen
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hofmann
authors.forename: Angelika
authors.initials: A
authors.lastname: Harneit
authors.forename: Joachim M
authors.initials: JM
authors.lastname: Weitzel
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002843:Chromatin / Q000737:chemistry; D051786:Cyclic AMP Response Element Modulator / Q000378:metabolism*; D004247:DNA / Q000737:chemistry; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1 / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D020218:Response Elements; D013087:Spermatids / Q000378:metabolism; D013737:Testis / Q000378:metabolism*
chemical_list: D002843:Chromatin; D057136:Nuclear Receptor Subfamily 6, Group A, Member 1; D051786:Cyclic AMP Response Element Modulator; D004247:DNA