DNA demethylation and USF regulate the meiosis-specific expression of the mouse Miwi

PLoS Genet. 2012;8(5):e1002716. doi: 10.1371/journal.pgen.1002716. Epub 2012 May 17.

Abstract

Miwi, a member of the Argonaute family, is required for initiating spermiogenesis; however, the mechanisms that regulate the expression of the Miwi gene remain unknown. By mutation analysis and transgenic models, we identified a 303 bp proximal promoter region of the mouse Miwi gene, which controls specific expression from midpachytene spermatocytes to round spermatids during meiosis. We characterized the binding sites of transcription factors NF-Y (Nuclear Factor Y) and USF (Upstream Stimulatory Factor) within the core promoter and found that both factors specifically bind to and activate the Miwi promoter. Methylation profiling of three CpG islands within the proximal promoter reveals a markedly inverse correlation between the methylation status of the CpG islands and germ cell type-specific expression of Miwi. CpG methylation at the USF-binding site within the E2 box in the promoter inhibits the binding of USF. Transgenic Miwi-EGFP and endogenous Miwi reveal a subcellular co-localization pattern in the germ cells of the Miwi-EGFP transgenic mouse. Furthermore, the DNA methylation profile of the Miwi promoter-driven transgene is consistent with that of the endogenous Miwi promoter, indicating that Miwi transgene is epigenetically modified through methylation in vivo to ensure its spatio-temporal expression. Our findings suggest that USF controls Miwi expression from midpachytene spermatocytes to round spermatids through methylation-mediated regulation. This work identifies an epigenetic regulation mechanism for the spatio-temporal expression of mouse Miwi during spermatogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Argonaute Proteins / genetics*
  • Binding Sites
  • CCAAT-Binding Factor / genetics
  • CCAAT-Binding Factor / metabolism
  • COS Cells
  • CpG Islands / genetics
  • DNA Methylation / genetics*
  • Epigenesis, Genetic*
  • Gene Expression Regulation
  • Germ Cells / growth & development
  • Germ Cells / metabolism
  • Male
  • Meiosis / genetics*
  • Mice
  • Mice, Transgenic
  • Promoter Regions, Genetic
  • Spermatids / growth & development
  • Spermatids / metabolism
  • Spermatocytes / growth & development
  • Spermatocytes / metabolism
  • Spermatogenesis / genetics*
  • Upstream Stimulatory Factors / genetics
  • Upstream Stimulatory Factors / metabolism

Substances

  • Argonaute Proteins
  • CCAAT-Binding Factor
  • Nfya protein, mouse
  • Piwil1 protein, mouse
  • Upstream Stimulatory Factors