Sex-specific exons control DNA methyltransferase in mammalian germ cells

Development. 1998 Mar;125(5):889-97. doi: 10.1242/dev.125.5.889.


The spermatozoon and oocyte genomes bear sex-specific methylation patterns that are established during gametogenesis and are required for the allele-specific expression of imprinted genes in somatic tissues. The mRNA for Dnmt1, the predominant maintenance and de novo DNA (cytosine-5)-methyl transferase in mammals, is present at high levels in postmitotic murine germ cells but undergoes alternative splicing of sex-specific 5' exons, which controls the production and localization of enzyme during specific stages of gametogenesis. An oocyte-specific 5' exon is associated with the production of very large amounts of active Dnmt1 protein, which is truncated at the N terminus and sequestered in the cytoplasm during the later stages of oocyte growth, while a spermatocyte-specific 5' exon interferes with translation and prevents production of Dnmt1 during the prolonged crossing-over stage of male meiosis. During the course of postnatal oogenesis, Dnmt1 is present at high levels in nuclei only in growing dictyate oocytes, a stage during which gynogenetic developmental potential is lost and biparental developmental potential is gained.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alternative Splicing
  • Animals
  • Base Sequence
  • Cytoplasm / metabolism
  • DNA (Cytosine-5-)-Methyltransferases / genetics*
  • DNA (Cytosine-5-)-Methyltransferases / metabolism
  • DNA Primers / genetics
  • Exons
  • Female
  • Male
  • Mice
  • Molecular Sequence Data
  • Oocytes / enzymology*
  • Oogenesis / genetics
  • Oogenesis / physiology
  • Protein Biosynthesis
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Sex Characteristics
  • Spermatogenesis / genetics
  • Spermatogenesis / physiology
  • Spermatozoa / enzymology*


  • DNA Primers
  • RNA, Messenger
  • DNA (Cytosine-5-)-Methyltransferases

Associated data

  • GENBANK/AF036007
  • GENBANK/AF036008
  • GENBANK/AF036009