ALPHA-B-CRYSTALLIN INTERACTS WITH INTERMEDIATE FILAMENTS IN RESPONSE TO STRESS

The small heat shock protein alpha B-crystallin interacts with interme diate filament proteins, Using a co-sedimentation assay, me showed tha t in vitro binding of alpha B-crystallin to peripherin and vimentin wa s temperature-dependent. Specifically, a synthetic peptide representin g the first ten residues of alpha B-crystallin was involved in this in teraction. When cells were submitted to different stress conditions su ch as serum starvation, hypertonic stress, or heat shock, we observed a dynamic reorganisation of the intermediate filament network, and con comitant recruitment of alpha B-crystallins on intermediate filament p roteins, Under normal conditions alpha B-crystallin was extracted from cells by detergent, In stressed cells, alpha B-crystallin colocalised with intermediate filament proteins, and became resistant to detergen t extraction, The intracellular state of alpha B-crystallin seemed to correlate directly with the remodelling of the intermediate filament n etwork in response to stress. This suggested that alpha B-crystallin f unctions as a molecular chaperone for intermediate filament proteins.