title: Epigenetic silencing of spermatocyte-specific and neuronal genes by SUMO modification of the transcription factor Sp3.
abstract: SUMO modification of transcription factors is linked to repression of transcription. The physiological significance of SUMO attachment to a particular transcriptional regulator, however, is largely unknown. We have employed the ubiquitously expressed murine transcription factor Sp3 to analyze the role of SUMOylation in vivo. We generated mice and mouse embryonic fibroblasts (MEFs) carrying a subtle point mutation in the SUMO attachment sequence of Sp3 (IKEE(553)D mutation). The E(553)D mutation impedes SUMOylation of Sp3 at K(551)in vivo, without affecting Sp3 protein levels. Expression profiling revealed that spermatocyte-specific genes, such as Dmc1 and Dnahc8, and neuronal genes, including Paqr6, Rims3, and Robo3, are de-repressed in non-testicular and extra-neuronal mouse tissues and in mouse embryonic fibroblasts expressing the SUMOylation-deficient Sp3E(553)D mutant protein. Chromatin immunoprecipitation experiments show that transcriptional de-repression of these genes is accompanied by the loss of repressive heterochromatic marks such as H3K9 and H4K20 tri-methylation and impaired recruitment of repressive chromatin-modifying enzymes. Finally, analysis of the DNA methylation state of the Dmc1, Paqr6, and Rims3 promoters by bisulfite sequencing revealed that these genes are highly methylated in Sp3wt MEFs but are unmethylated in Sp3E(553)D MEFs linking SUMOylation of Sp3 to tissue-specific CpG methylation. Our results establish SUMO conjugation to Sp3 as a molecular beacon for the assembly of repression machineries to maintain tissue-specific transcriptional gene silencing.
authors.affiliation: Institute of Molecular Biology and Tumor Research, Philipps-University of Marburg, Marburg, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Stielow
authors.forename: Imme
authors.initials: I
authors.lastname: Krüger
authors.forename: Rolf
authors.initials: R
authors.lastname: Diezko
authors.forename: Florian
authors.initials: F
authors.lastname: Finkernagel
authors.forename: Nynke
authors.initials: N
authors.lastname: Gillemans
authors.forename: John
authors.initials: J
authors.lastname: Kong-a-San
authors.forename: Sjaak
authors.initials: S
authors.lastname: Philipsen
authors.forename: Guntram
authors.initials: G
authors.lastname: Suske
mesh_terms: D000818:Animals; D002843:Chromatin / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D020868:Gene Silencing; D018390:Gene Targeting; D008297:Male; D008540:Meiosis / Q000235:genetics; D051379:Mice; D008817:Mice, Mutant Strains; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009928:Organ Specificity / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D051705:Sp3 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D013090:Spermatocytes / Q000378:metabolism*; D058207:Sumoylation / Q000235:genetics*
chemical_list: D002843:Chromatin; D012097:Repressor Proteins; C497122:Sp3 protein, mouse; D051705:Sp3 Transcription Factor