Jost Klawitter a, d , Christopher J. Rivard b , Lewis M. Brown b , Juan M. Capasso b , Nestor E. Almeida b , Arvid B. Maunsbach c , Kaarina Pihakaski-Maunsbach c , Tomas Berl b , Dieter Leibfritz d , Uwe Christians a , Laurence Chan b
05 May 2008
Background: The genomic response to adaptation of IMCD3 cells to hypertonicity results in both upregulation and downregulation of a variety of genes. Method: The present study was undertaken to assess the metabonomic and proteomic response of IMCD3 cells that have been chronically adapted to hypertonicity (600 and 900 mosm/kg H<sub>2</sub>O) as compared to cells under isotonic conditions. Results: Adaptation of IMCD3 cells to hypertonic conditions resulted in a change of a wide range of organic osmolytes, including sorbitol (+8,291%), betaine (+1,099%), myo-inositol (+669%), taurine (+113%) and glycerophosphorylcholine (+61%). Evaluation of the polyol pathway for sorbitol production revealed a reduction in sorbitol dehydrogenase and an increase in aldose reductase mRNA in adapted cells. Proteome analysis revealed increased expression of six glycolytic proteins, including malic enzyme and pyruvate carboxylase, indicating the activation of the pyruvate shunt and changes in glucose metabolism. This study showed that the observed reduction in cell replication could possibly reflect a redirection of cellular energy from cell growth and replication to maintenance of intracellular ion levels in chronically adapted cells. Conclusion: The combined metabonomic and proteomic analysis was shown to be a very helpful tool for the analysis of the effects caused by chronic adaptation to hypertonicity. It made it possible to better evaluate the importance of certain changes that occur in the process of adaptation.