A two-dimensional electrophoretic analysis of the heat-shock-induced proteins of human cells

Using two-dimensional electrophoresis, we have investigated the responses of human cells in culture to heat shock and to various chemical agents producing a similar effect. These treatments result in the induction of increased synthesis of several specific proteins. One (HShock:1, SDS-molecular mass about 65000) is increased by about 350-fold over the amount in untreated cells. Computer analysis of time-course studies indicates, however, that rates of synthesis of various proteins other than the classical "heat shock proteins" are affected, some of these alterations following time courses quite different from the main (HShock) inductions. The heat shock effect is thus much more complicated than previously realized. We purified the HShock:1 protein from heat-shocked human lymphoblastoid cells, and prepared a rabbit antiserum specific for HShock:1 on nitrocellulose two-dimensional gel transfers of total lymphoblastoid cell protein. A survey of mouse tissues shows high concentrations of an HShock:1-like protein in the testis, and human testes also appears to contain substantial (though lower) concentrations. These results are consistent with the hypothesis (derived from the tissue-culture studies) that the heat shock effect is a general response to the need for increased protein catabolism within the cell. Increased concentrations of HShock:1 are also observed in preparations of blood leukocytes collected from patients after surgery, indicating that some types of physiological trauma may induce the heat shock proteins in man. Using the antiHShock:1 antibody in an immunoassay, it will be possible to systematically examine HShock:1 concentrations in plasma and leukocytes, thereby opening up the possibility of a clinical test based for the first time upon an inducible aspect of cellular gene expression.