A critical role of noggin in developing folate-nonresponsive NTD in Fkbp8 -/- embryos

Childs Nerv Syst. 2014 Aug;30(8):1343-53. doi: 10.1007/s00381-014-2428-1. Epub 2014 May 10.

Abstract

Purpose: Maternal folate intake has reduced the incidence of human neural tube defects by 60-70 %. However, 30-40 % of cases remain nonresponsive to folate intake. The main purpose of this study was to understand the molecular mechanism of folate nonresponsiveness in a mouse model of neural tube defect.

Methods: We used a folate-nonresponsive Fkbp8 knockout mouse model to elucidate the molecular mechanism(s) of folate nonresponsiveness. Neurospheres were grown from neural stem cells isolated from the lumbar neural tube of E9.5 Fkbp8 (-/-) and wild-type embryos. Immunostaining was used to determine the protein levels of oligodendrocyte transcription factor 2 (Olig2), Nkx6.1, class III beta-tubulin (TuJ1), O4, glial fibrillary acidic protein (GFAP), histone H3 Lys27 trimethylation (H3K27me3), ubiquitously transcribed tetratricopeptide repeat (UTX), and Msx2, and quantitative real-time (RT)-PCR was used to determine the message levels of Olig2, Nkx6.1, Msx2, and noggin in neural stem cells differentiated in the presence and absence of folic acid.

Results: Fkbp8 (-/-)-derived neural stem cells showed (i) increased noggin expression; (ii) decreased Msx2 expression; (iii) premature differentiation--neurogenesis, oligodendrogenesis (Olig2 expression), and gliogenesis (GFAP expression); and (iv) increased UTX expression and decreased H3K27me3 polycomb modification. Exogenous folic acid did not reverse these markers.

Conclusions: Folate nonresponsiveness could be attributed in part to increased noggin expression in Fkbp8 (-/-) embryos, resulting in decreased Msx2 expression. Folate treatment further increases Olig2 and noggin expression, thereby exacerbating ventralization.

Publication types

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

MeSH terms

  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Proliferation / drug effects
  • Cell Proliferation / physiology
  • Disease Models, Animal
  • Embryo, Mammalian
  • Female
  • Folic Acid / adverse effects*
  • Gene Expression Regulation, Developmental / drug effects
  • Gene Expression Regulation, Developmental / genetics*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Humans
  • Jumonji Domain-Containing Histone Demethylases
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neural Stem Cells / drug effects
  • Neural Stem Cells / metabolism
  • Neural Tube Defects* / chemically induced
  • Neural Tube Defects* / genetics
  • Neural Tube Defects* / metabolism
  • Pregnancy
  • Tacrolimus Binding Proteins / deficiency*
  • Tacrolimus Binding Proteins / genetics

Substances

  • Carrier Proteins
  • Fkbp8 protein, mouse
  • Homeodomain Proteins
  • MSX2 protein
  • noggin protein
  • Folic Acid
  • Jumonji Domain-Containing Histone Demethylases
  • Kdm6b protein, mouse
  • Tacrolimus Binding Proteins