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Gene expression profiling and immune fluorescence implicate cellular redifferentiation induced by hypertonicity in primary cultured IMCD cells
Author(s) -
Edemir Bayram,
Klokkers Jens,
Pavenstädt Hermann,
Schlatter Eberhard
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.817.1
Subject(s) - tonicity , biology , gene expression , microbiology and biotechnology , gene , gene expression profiling , enhancer , osmotic concentration , biochemistry
The cells of the renal inner medulla are challenged with an environment consisting of high osmolality mediated mainly by Na+ and urea. High tonicity leads to the activation of the tonicity enhancer binding protein, which induces the expression of several transporters and enzymes. This in turn leads to the cellular accumulation of organic osmolytes thereby protecting the cells from high extracellular tonicity. Although several genes that are induced by tonicity are known, a global gene expression profile and analysis of pathways is missing. We used primary cultured rat renal inner medullary collecting duct cells which were cultivated for 6 days at 300, 600 or 900 mosmol/kg. Total RNA was isolated and prepared for hybridization on Rat Gene 1.0 ST GeneChip. Differentially expressed genes were identified using the BRB Array Tools and functional molecular network were identified with Ingenuity Pathway Analysis. Comparing cells grown in 300 vs. 600 mosmol/kg, more than 1600 and vs. 900 mosmol/kg more than 3300 genes were differentially expressed. In both cases the ratio between the up and down regulated genes was approximately one. While 1300 were common in both comparisons 290 at 600 and more than 2000 genes at 900 mosmol/kg were unique. Besides known genes the expression of several other genes were identified for which regulation by tonicity had not been described before. Cellular morphology was markedly modified with increases in culture medium tonicity. Tonicity induced actin reorganization and morphological changes at the cell to cell contacts. It also induced a hypertrophic phenotype. The adaptation to a higher tonicity is not only associated with massive changes in gene expression but also with changes in cell morphology. This implicates that tonicity induces cellular redifferentiation.