Determination of the NFAT5/TonEBP transcription factor in the human and ovine placenta.

Osmotic stress results in the accumulation of osmolytes in tissues. Synthesis of these osmolytes is mediated by the transcription factor NFAT5/TonEBP in the human kidney. We tested for the presence of NFAT5 mRNA and protein in the human and ovine placenta and confirmed sorbitol and inositol osmolyte concentrations in these tissues. To determine NFAT5 protein, human and ovine placenta were tested for inositol, sorbitol and glucose using high performance liquid chromatography (HPLC). Additionally, RNA was extracted and cDNA was made from these tissues. PCR was performed and products were sequenced. Western blotting was used to assess the expression of the NFAT5 protein. Human and ovine placenta demonstrated: 1) high concentrations of sorbitol and inositol, 2) presence of NFAT5 mRNA, 3) confirmation by NFAT5 sequence identity, and 4) presence of NFAT5 protein. NFAT5 is present in the ovine and human placenta at the RNA and protein levels that suggest a role for this protein in the induction of these osmolytes. Further trophoblast studies of osmotic stress effects on osmolytes are planned.