Mouse SYCP2 is required for synaptonemal complex assembly and chromosomal synapsis during male meiosis

J Cell Biol. 2006 May 22;173(4):497-507. doi: 10.1083/jcb.200603063.


During meiosis, the arrangement of homologous chromosomes is tightly regulated by the synaptonemal complex (SC). Each SC consists of two axial/lateral elements (AEs/LEs), and numerous transverse filaments. SC protein 2 (SYCP2) and SYCP3 are integral components of AEs/LEs in mammals. We find that SYCP2 forms heterodimers with SYCP3 both in vitro and in vivo. An evolutionarily conserved coiled coil domain in SYCP2 is required for binding to SYCP3. We generated a mutant Sycp2 allele in mice that lacks the coiled coil domain. The fertility of homozygous Sycp2 mutant mice is sexually dimorphic; males are sterile because of a block in meiosis, whereas females are subfertile with sharply reduced litter size. Sycp2 mutant spermatocytes exhibit failure in the formation of AEs and chromosomal synapsis. Strikingly, the mutant SYCP2 protein localizes to axial chromosomal cores in both spermatocytes and fetal oocytes, but SYCP3 does not, demonstrating that SYCP2 is a primary determinant of AEs/LEs and, thus, is required for the incorporation of SYCP3 into SCs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone / chemistry
  • Chromosomal Proteins, Non-Histone / genetics*
  • Chromosomal Proteins, Non-Histone / metabolism
  • Chromosome Pairing / genetics*
  • Chromosomes / genetics*
  • Conserved Sequence / genetics
  • DNA-Binding Proteins
  • Female
  • Infertility, Female / genetics
  • Infertility, Male / genetics
  • Male
  • Meiosis / genetics*
  • Mice
  • Mice, Knockout
  • Molecular Sequence Data
  • Mutation / genetics
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Oocytes / metabolism
  • Oocytes / ultrastructure
  • Protein Structure, Tertiary / genetics
  • Sex Characteristics
  • Sex Differentiation / genetics
  • Spermatocytes / metabolism*
  • Spermatocytes / ultrastructure
  • Spermatogenesis / genetics
  • Synaptonemal Complex / metabolism*
  • Synaptonemal Complex / ultrastructure


  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Sycp2 protein, mouse
  • Sycp3 protein, mouse

Associated data

  • GENBANK/DQ103262