Dear Colleagues,

Small Heat Shock Proteins (sHSPs) constitute a diverse chaperone family that share conserved alpha-crystallin domain (ACD) and dynamic N- and C-terminal extensions (NET). sHSPs are present in cells under normal conditions as large oligomers in both inactive and dynamic states. However, stress conditions cause an increase in cellular sHSP levels with subsequent conformational rearrangements and activation to release substrate-binding sites present in the ACD and NTE. sHSPs interact with unfolded and misfolded proteins to facilitate their refolding or degradation by chaperones and co-factors (e.g. Hsp 70- Hsp100) in an ATP-dependent manner. Substrate recognition and binding by sHSPs are essential for their chaperone function in protein quality control (PQC) during stress conditions. Moreover, sHSPs can maintain the dynamic state of phase-separated stress granules (SGs) that store mRNA and translation factors. They do this by reducing misfolds or incorrect refolding inside the SGs. Overall, sHSPs are essential during stressful conditions at which time they perform their characteristic function of molecular chaperones. They are also significantly involved in various pathological conditions and perform several functions to modulate the immune response. Moreover, deregulation of SHSP expression has been implicated in the carcinogenic process and in various cardiovascular and nervous system diseases.

Assoc. Prof. Francesca Rappa

Guest Editor