title: The Dnmt3b splice variant is specifically expressed in in vitro-manipulated blastocysts and their derivative ES cells.
abstract: Manipulation of preimplantation embryos in vitro, such as in vitro fertilization (IVF), in vitro culture (IVC), intracytoplasmic sperm injection (ICSI), somatic cell nuclear transfer (SCNT) and other assisted reproduction technologies (ART), has contributed to the development of infertility treatment and new animal reproduction methods. However, such embryos often exhibit abnormal DNA methylation patterns in imprinted genes and centromeric satellite repeats. These DNA methylation patterns are established and maintained by three DNA methyltransferases: Dnmt1, Dnmt3a and Dnmt3b. Dnmt3b is responsible for the creation of methylation patterns during the early stage of embryogenesis and consists of many alternative splice variants that affect methylation activity; nevertheless, the roles of these variants have not yet been identified. In this study, we found an alternatively spliced variant of Dnmt3b lacking exon 6 (Dnmt3bΔ6) that is specific to mouse IVC embryos. Dnmt3bΔ6 also showed prominent expression in embryonic stem (ES) cells derived from in vitro manipulated embryos. Interestingly, IVC blastocysts were hypomethylated in centromeric satellite repeat regions that could be susceptible to methylation by Dnmt3b. In vitro methylation activity assays showed that Dnmt3bΔ6 had lower activity than normal Dnmt3b. Our findings suggest that Dnmt3bΔ6 could induce a hypomethylation status especially in in vitro manipulated embryos.
authors.affiliation: Laboratory of Genome Science, Biosignal Genome Resource Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan.
authors.forename: Takuro
authors.initials: T
authors.lastname: Horii
authors.forename: Isao
authors.initials: I
authors.lastname: Suetake
authors.forename: Eikichi
authors.initials: E
authors.lastname: Yanagisawa
authors.forename: Sumiyo
authors.initials: S
authors.lastname: Morita
authors.forename: Mika
authors.initials: M
authors.lastname: Kimura
authors.forename: Yasumitsu
authors.initials: Y
authors.lastname: Nagao
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imai
authors.forename: Shoji
authors.initials: S
authors.lastname: Tajima
authors.forename: Izuho
authors.initials: I
authors.lastname: Hatada
mesh_terms: D017398:Alternative Splicing / Q000235:genetics / Q000502:physiology; D000818:Animals; D001755:Blastocyst / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D002478:Cells, Cultured; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics; D046149:Embryo Culture Techniques; D053595:Embryonic Stem Cells / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011247:Pregnancy; D051381:Rats; D011916:Rats, Inbred F344; D013048:Specimen Handling; D000097584:DNA Methyltransferase 3B
chemical_list: D004248:DNA (Cytosine-5-)-Methyltransferases; D007527:Isoenzymes; D000097584:DNA Methyltransferase 3B