Mitochondrial impairment and recovery after heat shock treatment in a human microglial cell line.

The application of a heat shock on the human microglial cell line (CHME 5) has been shown to cause cytoskeleton modifications and alterations in phosphorylated metabolite content (Macouillard-Poulletier de Gannes et al., 1998a Metabolic and cellular characterization of immortalized human microglial cells under heat stress. Neurochem. Int. 33, 61-73). In this study, we focused on the possible involvement of mitochondria in this heat stress response. The cell respiratory properties were followed during the recovering period and the possible relationships between mitochondria and the cytoskeleton were studied. We observed that the heat shock induced changes in mitochondrial activity due to protein denaturation, rather than mitochondrial loss. Furthermore, these alterations were correlated with cytoskeleton disorganization since vimentine, tubuline and mitochondria shift, simultaneously, to a perinuclear location. The perturbations of the mitochondrial distribution persisted until cytoskeleton networks had recovered. Nevertheless, the respiratory properties recovered rapidly suggesting a renaturation of mitochondrial proteins in connection with mitochondrial cytoplasmic redistribution.