Differential distribution of the mitochondrial heat-shock protein 60 in rat gastrointestinal tract

Immunohistochemical studies on various parts of the rat gastrointestinal tract by means of an antibody against the mitochondrial chaperonin, heat-shock protein 60 (hsp60), has revealed a cell-specific distribution pattern. The active form of hsp60 is a heptameric complex that is involved in the import and refolding of nuclear-encoded proteins destined for the mitochondrial matrix. This chaperonin is detectable in highly replicating cells, e. g., keratinizing cells of the esophagus and short-living epithelial cells of the intestine. In the stomach, some of the oxyntic cells contain hsp60-positive mitochondria lying near intracellular canaliculi. Neuronal cells of the enteric nervous system present intense positive staining for hsp60 in some areas. All other non-epithelial cells of the digestive tract show weak or no hsp60 immunoreactivity. The presence of hsp60 in mitochondria seems to reflect two different forms of mitochondrial renewal: (1) total reformation of mitochondria and their content after mitotic division and (2) regeneration of these organelles following high activity, e. g., ATP synthesis.