αB-crystallin interacts with intermediate filaments in response to stress

The small heat shock protein αB-crystallin interacts with intermediate filament proteins. Using a co-sedimentation assay, we showed that in vitro binding of αB-crystallin to peripherin and vimentin was temperature-dependent. Specifically, a synthetic peptide representing the first ten residues of αB-crystallin was involved in this interaction. When cells were submitted to different stress conditions such as serum starvation, hypertonic stress, or heat shock, we observed a dynamic reorganisation of the intermediate filament network, and concomitant recruitment of αB-crystallins on intermediate filament proteins. Under normal conditions αB-crystallin was extracted from cells by detergent. In stressed cells, αB-crystallin colocalised with intermediate filament proteins, and became resistant to detergent extraction. The intracellular state of αB-crystallin seemed to correlate directly with the remodelling of the intermediate filament network in response to stress. This suggested that αB-crystallin functions as a molecular chaperone for intermediate filament proteins.