Two-dimensional electrophoretic mapping of hepatic and renal stress proteins.

Cellular stress proteins and molecular chaperones are responsive to a variety of stressors and therefore comprise an ideal set of proteins with the potential to be used as biomarkers of chemical toxicity. We have investigated the expression of a group of well established heat shock and glucose-regulated proteins in the rat liver and kidney using large-scale two-dimensional protein electrophoresis and computerized image analysis. Our goal was to determine the level of their expression in unstressed target tissues and map their coordinate positions on conventional format two-dimensional electrophoresis (2-DE) gels. All the proteins studied, except for Hsp25 (heat-shock protein) whose expression fell below the level of analyzable detection, were constitutively expressed in liver and kidney. With the exception of Hsp70, all the stress proteins analyzed were constitutively more abundant in the liver than the kidney. Comparison of the sum total of all stress protein abundances revealed a nearly threefold higher level of expression in the liver than the kidney. Our results suggest that this group of proteins has significant responsibilities in normal, unstressed cells, due to their constitutive abundance. Correspondingly, the 2-DE stress protein pattern established in this study may be very useful in toxicologic screening as well as describing a broad range of molecular effects of xenobiotic exposure.