title: Expression of DNMT3A transcripts and nucleolar localization of DNMT3A protein in human testicular and fibroblast cells suggest a role for de novo DNA methylation in nucleolar inactivation.
abstract: Transcriptional silencing during differentiation of human male germ cells and serum starvation of human fibroblasts is controlled by epigenetic mechanisms that involve de novo DNA methylation. It is associated with high expression of different transcripts of the DNA methyltransferase 3A (DNMT3A) gene that encode two isoforms with de novo methyltransferase activity and one without catalytic activity. Western blots revealed that DNMT3A protein (with catalytic domain) is present at low levels in several tissues and at increased levels in testicular cells and growth-arrested fibroblasts. Immunofluorescence experiments localized DNMT3A to discrete nucleolar foci in B spermatogonia and resting fibroblasts. The data here suggest a role for de novo DNA methylation in nucleolar inactivation.
authors.affiliation: Institute for Human Genetics, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Danuta
authors.initials: D
authors.lastname: Galetzka
authors.forename: Tim
authors.initials: T
authors.lastname: Tralau
authors.forename: Raimund
authors.initials: R
authors.lastname: Stein
authors.forename: Thomas
authors.initials: T
authors.lastname: Haaf
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology*; D002466:Cell Nucleolus / Q000378:metabolism; D002478:Cells, Cultured; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000096:biosynthesis*; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D020868:Gene Silencing / Q000502:physiology; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis; D008297:Male; D012333:RNA, Messenger; D013093:Spermatogonia / Q000166:cytology / Q000378:metabolism*; D013737:Testis / Q000166:cytology / Q000201:enzymology*
chemical_list: C000717967:DNMT3A protein, human; D007527:Isoenzymes; D012333:RNA, Messenger; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A