Increased expression of EGR1 and KLF4 by polysulfide via activation of the ERK1/2 and ERK5 pathways in cultured intestinal epithelial cells.

Sodium trisulfide (Na2S3) releases hydrogen polysulfide (H2Sn) and is useful for the investigation of the effects of H2Sn on the cell functions. In the present study, we first examined the effects of Na2S3 on the gene expression of IEC-6 cells, a rat intestinal epithelial cell line. Microarray analysis and reverse transcription-polymerase chain reaction analysis revealed that Na2S3 increased the gene expression of early growth response 1 (EGR1) and Kruppel-like transcription factor 4 (KLF4). It was interesting that U0126, an inhibitor of the activation of extracellular signal-regulated kinase 1 (ERK1), ERK2, and ERK5, inhibited the Na2S3-induced gene expression of EGR1 and KLF4. Na2S3 activated ERK1 and ERK2 (ERK1/2) within 15 min. In addition to ERK1/2, Na2S3 activated ERK5. We noticed that the electrophoretic mobility of ERK5 was decreased after Na2S3 treatment. Phos-tag analysis and in vitro dephosphorylation of the cell extracts indicated that the gel-shift of ERK5 was due to its phosphorylation. The gel-shift of ERK5 was inhibited completely by both U0126 and ERK5-IN-1, a specific inhibitor of ERK5. From these results, we concluded that the gel-shift of ERK5 was induced through autophosphorylation by activated ERK5 after Na2S3 treatment. The present study suggested that H2Sn affected various functions of intestinal epithelial cells through the activation of the ERK1/2 and ERK5 pathways.