SMALL STRESS PROTEINS - CHAPERONES THAT ACT AS REGULATORS OF INTRACELLULAR REDOX STATE AND PROGRAMMED CELL-DEATH

Small stress proteins (sHsp) are molecular chaperones whose expression was shown to enhance the survival of mammalian cells exposed to numer ous types of injuries that lead to death, including heat shock, oxidat ive stress as well as treatments with anti-cancerous and apoptosis-ind ucing agents. Here, a summary of the most recent results concerning th e protective activity of this family of proteins against programmed ce ll death is presented. (1) sHsp enhance the survival of cells exposed to oxidative stress, a phenomenon which is linked to the ability of th ese proteins to decrease the intracellular level of reactive oxygen sp ecies in a glutathione dependent way. (2) sHsp protect against apoptos is mediated by different agents including staurosporine, etoposide and the Fas ligand. (3) An interesting and particular aspect of sHsp conc erns their transient expression during the cell division to differenti ation transition. In this context, sHsp expression was shown to be ess ential for preventing differentiating cells from undergoing apoptosis. Small stress proteins appear therefore as novel regulators that inter fere with programmed cell death induced by different pathways.