Culture shock. Synthesis of heat-shock-like proteins in fresh primary cell cultures.

The isolation of Xenopus liver, lung and testis cells by collagenase digestion of the tissue, followed by Percoll density gradient centrifugation, was characterized by the preferential synthesis of two proteins whose size and charge were similar to 70 and 85 kD heat-shock proteins. The synthesis of these two heat-shock-like proteins, relative to that of total protein, declined gradually in the first 3-4 days after the cells were plated out for primary culture. In fresh primary cultures of liver parenchymal cells albumin mRNA concentration declined rapidly and plateaued at 3-4 days of culture. Freshly isolated male Xenopus hepatocytes were refractory to induction by estrogen of vitellogenin gene transcription but they reacquired hormonal response during the first 3 days of culture. Both of these differentiated phenotypic functions of the Xenopus hepatocytes were quantitatively associated with the decline in synthesis of hsp-like proteins in freshly prepared primary cell cultures. Freshly isolated or heat-shocked hepatocytes exhibited a rounded shape with little intercellular contacts, whereas during the recovery period of 3 days they acquired a flattened shape with a high degree of intercellular and cell-substratum interaction. These results present the first evidence for the preferential synthesis of heat-shock-like proteins by procedures for establishing primary cell cultures. They emphasize the necessity of monitoring normal and heat-shock protein synthesis and cell morphology before using primary cell cultures for studying normal regulatory and developmental processes.