MOLECULAR CHAPERONES AND THE CENTROSOME - A ROLE FOR HSP-73 IN CENTROSOMAL REPAIR FOLLOWING HEAT-SHOCK TREATMENT

In the accompanying paper (Brown, C. R., Doxsey, S. J., Hong-Brown, L. W., Martin, R. L., and Welch, W. J. (1996) J. Biol. Chem. 271, 824-83 2) two molecular chaperones, hsp 73 and TCP-1, were shown to be integr al components of the centrosome. Here we show that heat shock treatmen t adversely affects both the structure and function of the centrosome, and that hsp 73 plays a role in the repair of the organelle. After he at shock treatment, the centrosome could not be identified via indirec t immunofluorescence and cells were unable to support microtubule regr owth. During recovery from heat shock, a strong correlation between th e return of staining of three centrosomal antigens (hsp 73, TCP-1, and pericentrin) and the recovery of microtubule regrowth properties was found. Incubation of cells with glycerol, a protein protective agent, prevented the heat induced alterations in the structure/function of th e centrosome. Likewise, the recovery of the structure and function of the centrosome after heat shock treatment was significantly accelerate d in cells first made thermotolerant. We provide evidence that this pr ocess is related to the levels of hsp 73 since: 1) microinjection of h sp 73 antibody blocked centrosomal reassembly and microtubule regrowth abilities following heat shock; and 2) microinjection of purified hsp 73 protein prior to heat shock treatment accelerated both the repair and function of the organelle, similar to that observed for thermotole rant cells.