Hypoxia in human trophoblasts stimulates the expression and secretion of connective tissue growth factor

Endocrinology. 2008 Jun;149(6):2952-8. doi: 10.1210/en.2007-1099. Epub 2008 Feb 21.

Abstract

The mechanisms underlying cellular injury when human placental trophoblasts are exposed to hypoxia are unclear. Connective tissue growth factor (CTGF) mediates cell injury and fibrosis in diverse tissues. We hypothesized that hypoxia enhances the production of CTGF in primary term human trophoblasts. Using cultured term primary human trophoblasts as well as villous biopsies from term human placentas, we showed that CTGF protein is expressed in trophoblasts. When compared with cells cultured in standard conditions (FiO2 = 20%), exposure of primary human trophoblasts to low oxygen concentration (FiO2 = 8% or <or= 1%) enhanced the expression of CTGF mRNA in a time-dependent manner, with a significant increase in CTGF levels after 16 h (2.7 +/- 0.7-fold; P < 0.01), reaching a maximum of 10.9 +/- 3.2-fold at 72 h. Whereas exposure to hypoxia had no effect on cellular CTGF protein levels, secretion of CTGF to the medium was increased after 16 h in hypoxia and remained elevated through 72 h. The increase in cellular CTGF transcript levels and CTGF protein secretion was recapitulated by exposure of trophoblasts to agents that enhance the activity of hypoxia-inducible factor (HIF)1alpha, including cobalt chloride or the proline hydroxylase inhibitor dimethyloxaloylglycine, and attenuated using the HIF1alpha inhibitor 2-methoxyestradiol. Although all TGFbeta isoforms stimulated the expression of CTGF in trophoblasts, only the expression of TGFbeta1 mRNA was enhanced by hypoxia. We conclude that hypoxia increases cellular CTGF mRNA levels and CTGF protein secretion from cultured trophoblasts, likely in a HIF1alpha-dependent manner.

Publication types

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

MeSH terms

  • Cell Hypoxia / drug effects
  • Cell Hypoxia / physiology
  • Connective Tissue Growth Factor
  • DNA Primers
  • Gene Expression Regulation / drug effects
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / pharmacology
  • Immediate-Early Proteins / genetics*
  • Immediate-Early Proteins / metabolism
  • Intercellular Signaling Peptides and Proteins / genetics*
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Monensin / pharmacology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Trophoblasts / drug effects
  • Trophoblasts / physiology*

Substances

  • CCN2 protein, human
  • DNA Primers
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Immediate-Early Proteins
  • Intercellular Signaling Peptides and Proteins
  • Connective Tissue Growth Factor
  • Monensin