Heat shock proteins in cell signaling and cancer

Heat Shock Proteins (HSPs) and their co-chaperones have well-established roles in regulating proteostasis within the cell, the nature of which continues to emerge with further study. To date, HSPs have been shown to be integral to protein folding and re-folding, protein transport, avoidance of protein aggregation, and modulation of protein degradation. Many cell signaling events are mediated by the chemical modification of proteins posttranslationally that can alter protein conformation and activity, although it is not yet known whether the changes in protein conformation induced by post-translational modifications (PTMs) are also dependent upon HSPs and their co-chaperones for subsequent protein re-folding. We discuss what is known regarding roles for HSPs and other molecular chaperones in cell signaling events with a focus on oncogenic signaling. We also propose a hypothesis by which Hsp70 and Hsp90 may co-operate to facilitate cell signaling events that may link PTMs with the cellular protein folding machinery.