Double Face of eHsp70 in Front of Different Situations. Multiple Role of eHsp70

The Hsp70 family is one of the best conserved and abundant member of the heat shock proteins (HSP). This family includes several members and in particular one constitutively expressed member (Hsc70) and another one inducibly expressed under several stress conditions (Hsp70). To date, the intracellular functions of Hsp70 are well defined, and increasing evidences establish its roles in the extracellular environment, such as cytoprotection and immunomodulation. Increasing evidences suggest that several cell types are able to release Hsp70 in the extracellular environment, both under physiological and stress conditions. At the same time many release mechanisms have been identified. This chapter briefly reviews recent advances in our understanding on extracellular Hsp70 role in both physiological and pathological conditions. A better comprehension will be useful to take advantage of its potential as a therapeutic target.