Enhancers of GnRH transcription embedded in an upstream gene use homeodomain proteins to specify hypothalamic expression

Mol Endocrinol. 2010 Oct;24(10):1949-64. doi: 10.1210/me.2010-0156. Epub 2010 Jul 28.

Abstract

GnRH, the central regulator of reproductive function, is produced by only approximately 800 highly specialized hypothalamic neurons. Previous studies identified a minimal promoter [GnRH minimal promoter (GnRH-P)] (-173/+1) and a neuron-specific enhancer [GnRH-enhancer (E)1] (-1863/-1571) as regulatory regions in the rat gene that confer this stringent specificity of GnRH expression to differentiated GnRH neurons. In transgenic mice, these two elements target only GnRH neurons but fail to drive expression in the entire population, suggesting the existence of additional regulatory regions. Here, we define two novel, highly conserved, upstream enhancers in the GnRH gene termed GnRH-E2 (-3135/-2631) and GnRH-E3 (-4199/-3895) that increase neuron-specific GnRH expression through interactions with GnRH-E1 and GnRH-P. GnRH-E2 and GnRH-E3 regulate GnRH expression through similar mechanisms via Oct-1, Msx1, and Dlx2, which bind both GnRH-E2 and the GnRH-E3 critical region at -3952/-3895. Overexpression of Dlx2 increases transcription through GnRH-E2 and GnRH-E3. Remarkably, these novel elements are contained within the 3' untranslated region of the neighboring upstream gene, yet are marked endogenously by histone modification signatures consistent with those of enhancers. Thus, GnRH-E2 and GnRH-E3 are novel regulatory elements that, together with GnRH-E1 and GnRH-P, confer the specificity of GnRH expression to differentiated and mature GnRH neurons.

Publication types

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

MeSH terms

  • 3' Untranslated Regions
  • Animals
  • Base Sequence
  • Cell Line
  • Enhancer Elements, Genetic*
  • Gonadotropin-Releasing Hormone / genetics*
  • Gonadotropin-Releasing Hormone / metabolism*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Humans
  • Hypothalamus / metabolism*
  • Mice
  • Molecular Sequence Data
  • Neurons / metabolism
  • Potassium Channels / genetics
  • Promoter Regions, Genetic
  • Rats
  • Sequence Alignment
  • Sequence Homology, Nucleic Acid
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic*

Substances

  • 3' Untranslated Regions
  • Homeodomain Proteins
  • Potassium Channels
  • Transcription Factors
  • Gonadotropin-Releasing Hormone