Retinoic acid, GABA-ergic, and TGF-beta signaling systems are involved in human cleft palate fibroblast phenotype

Mol Med. 2006 Sep-Oct;12(9-10):237-45. doi: 10.2119/2006–00026.Baroni.


During embryogenesis, a complex interplay between extracellular matrix (ECM) molecules, regulatory molecules, and growth factors mediates morphogenetic processes involved in palatogenesis. Transforming growth factor-beta (TGF-beta), retinoic acid (RA), and gamma-aminobutyric acid (GABA)ergic signaling systems are also potentially involved. Using [3H]glucosamine and [35S]methionine incorporation, anion exchange chromatography, semiquantitative radioactive RT-PCR, and a TGF-beta binding assay, we aimed to verify the presence of phenotypic differences between primary cultures of secondary palate (SP) fibroblasts from 2-year-old subjects with familial nonsyndromic cleft lip and/or palate (CLP-SP fibroblasts) and age-matched normal SP (N-SP) fibroblasts. The effects of RA--which, at pharmacologic doses, induces cleft palate in newborns of many species--were also studied. We found an altered ECM production in CLP-SP fibroblasts that synthesized and secreted more glycosaminoglycans (GAGs) and fibronectin (FN) compared with N-SP cells. In CLP-SP cells, TGF-beta3 mRNA expression and TGF-beta receptor number were higher and RA receptor-alpha (RARA) gene expression was increased. Moreover, we demonstrated for the first time that GABA receptor (GABRB3) mRNA expression was upregulated in human CLP-SP fibroblasts. In N-SP and CLP-SP fibroblasts, RA decreased GAG and FN secretion and increased TGF-beta3 mRNA expression but reduced the number of TGF-beta receptors. TGF-beta receptor type I mRNA expression was decreased, TGF-beta receptor type II was increased, and TGF-beta receptor type III was not affected. RA treatment increased RARA gene expression in both cell populations but upregulated GABRB3 mRNA expression only in N-SP cells. These results show that CLP-SP fibroblasts compared with N-SP fibroblasts exhibit an abnormal phenotype in vitro and respond differently to RA treatment, and suggest that altered crosstalk between RA, GABAergic, and TGF-beta signaling systems could be involved in human cleft palate fibroblast phenotype.

MeSH terms

  • Cell Count
  • Cell Growth Processes / drug effects
  • Cell Survival / drug effects
  • Cells, Cultured
  • Child, Preschool
  • Cleft Palate / pathology*
  • Female
  • Fibroblasts / drug effects
  • Fibroblasts / pathology*
  • Fibronectins / metabolism
  • Gene Expression Regulation / drug effects
  • Glucosamine / metabolism
  • Glycosaminoglycans / metabolism
  • Humans
  • Male
  • Phenotype
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, GABA-A / metabolism*
  • Receptors, Transforming Growth Factor beta / genetics
  • Signal Transduction / drug effects*
  • Transforming Growth Factor beta3 / genetics
  • Transforming Growth Factor beta3 / metabolism*
  • Tretinoin / pharmacology*


  • Fibronectins
  • GABRB3 protein, human
  • Glycosaminoglycans
  • RNA, Messenger
  • Receptors, GABA-A
  • Receptors, Transforming Growth Factor beta
  • Transforming Growth Factor beta3
  • Tretinoin
  • Glucosamine