Altering Glypican-1 levels modulates canonical Wnt signaling during trigeminal placode development

Dev Biol. 2010 Dec 1;348(1):107-18. doi: 10.1016/j.ydbio.2010.09.017. Epub 2010 Sep 27.

Abstract

Glypicans are conserved cell surface heparan sulfate proteoglycans expressed in a spatiotemporally regulated manner in many developing tissues including the nervous system. Here, we show that Glypican-1 (GPC1) is expressed by trigeminal placode cells as they ingress and contribute to trigeminal sensory neurons in the chick embryo. Either expression of full-length or truncated GPC1 in vivo causes defects in trigeminal gangliogenesis in a manner that requires heparan sulfate side chains. This leads to either abnormal placodal differentiation or organization, respectively, with near complete loss of the ophthalmic (OpV) trigeminal ganglion in the most severe cases after overexpression of full-length GPC1. Interestingly, modulating GPC1 alters levels of endogenous Wnt signaling activity in the forming trigeminal ganglion, as indicated by Wnt reporter expression. Accordingly, GPC1 overexpression phenocopies Wnt inhibition in causing loss of OpV placodal neurons. Furthermore, increased Wnt activity rescues the effects of GPC1 overexpression. Taken together, these results suggest that appropriate levels of GPC1 are essential for proper regulation of canonical Wnt signaling during differentiation and organization of trigeminal placodal cells into ganglia.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Chick Embryo
  • Gene Expression Regulation, Developmental*
  • Glycosylphosphatidylinositols / metabolism
  • Glypicans / deficiency
  • Glypicans / genetics
  • Glypicans / physiology*
  • Heparitin Sulfate / physiology
  • Nerve Tissue Proteins / physiology*
  • Neurogenesis / physiology*
  • Phenotype
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Recombinant Fusion Proteins / physiology
  • Sensory Receptor Cells / cytology
  • Signal Transduction / physiology*
  • Trigeminal Ganglion / embryology*
  • Trigeminal Ganglion / ultrastructure
  • Wnt Proteins / physiology*
  • beta Catenin / chemistry
  • beta Catenin / physiology

Substances

  • Glycosylphosphatidylinositols
  • Glypicans
  • Nerve Tissue Proteins
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • Wnt Proteins
  • beta Catenin
  • Heparitin Sulfate