Cold shock induces the synthesis of stress proteins in human keratinocytes

Heat shock proteins or stress proteins are synthesized when cells are exposed to a wide variety of physiologic stresses. The stress response is evolutionarily highly conserved, suggestive of an essential function(s) for the survival of organisms, protecting them from harmful trauma. Exposure to cold induces a stress response in organisms such as Drosophila melanogaster and Sarcophaga crassipalpis and this led us to determine whether or not cold shock responses occur in human skin after exposure to cold such as might occur during cryopreservation of tissues or cryosurgery. Biopsies taken from fresh human skin at chest surgery were exposed to 4, 15, 20, and 37 degrees C (control) for 60 min and then allowed to incorporate 35S-methionine at 37 degrees C for up to 3 h. Proteins from the epidermis were extracted and analyzed by sodium dodecyl-sulfate-polyacrylamide gel electrophoresis. At 15 degrees C and below there was increased synthesis of 90 and 72 kD proteins 2 h after shocking. The 72-kD protein was identified as a heat shock protein using a monoclonal antibody to HSP72 and it is proposed from electrophoretic evidence that the 90-kD protein is also a heat shock protein. Clearly, cold shock stimulates a stress response in human epidermis altering the spectrum of proteins expressed and inducing the synthesis of heat shock proteins.