Regulation of glutathione S-transferase enzymes in primary cultures of rathepatocytes maintained under various matrix configurations

Primary rat hepatocytes were cultured under various matrix and media condit ions and examined after 1 week for the expression and regulation of cytosol ic glutathione S-transferase (GST) enzymes. Striking effects on cell morpho logy were observed in relation to the different matrix conditions, whereas media effects were less prominent. Hepatocytes cultured in serum-free Dulbe cco's modified Eagle's medium (DMEM) or modified Chee's medium (MCM) mainta ined similar levels of total GST protein regardless of the matrix configura tion or corresponding cell integrity. However, HPLC analysis showed a diffe rential expression pattern of individual GST subunits in both a time- and m edium-dependent fashion. A variable, but pronounced, matrix and medium effe ct was observed on the induction of total GST expression by various prototy pical inducers. Dexamethasone (10 mu M) induced subunits A2, M1 and M2 in a medium- and matrix-dependent fashion, whereas phenobarbital (100 mu M) ind uced significantly only subunit A2. beta-Naphthoflavone (50 mu M) suppresse d all GST subunit expression except subunit P1, which was induced in a matr ix- and medium-dependent fashion. These studies show that total basal level expression of GSTs in vitro is reflective of a concomitant increase in mu and pi class subunits and a decrease in oc class subunits, Moreover, the ma trix and medium conditions influence both the basal and inducible expressio n of GST subunits in cultured rat hepatocytes. (C) 2000 Elsevier Science Lt d. All rights reserved.