DIFFERENTIAL DISTRIBUTION OF THE MITOCHONDRIAL HEAT-SHOCK PROTEIN-60 IN RAT GASTROINTESTINAL-TRACT

Immunohistochemical studies on various parts of the rat gastrointestin al tract by means of an antibody against the mitochondrial chaperonin, heat-shock protein 60 (hsp60), has revealed a cell-specific distribut ion pattern. The active form of hsp60 is a heptameric complex that is involved in the import and refolding of nuclear-encoded proteins desti ned for the mitochondrial matrix. This chaperonin is detectable in hig hly replicating cells, e.g., keratinizing cells of the esophagus and s hort-living epithelial cells of the intestine. In the stomach, some of the oxyntic cells contain hsp60-positive mitochondria lying near intr acellular canaliculi. Neuronal cells of the enteric nervous system pre sent intense positive staining for hsp60 in some areas. All other non- epithelial cells of the digestive tract show weak or no hsp60 immunore activity. The presence of hsp60 in mitochondria seems to reflect two d ifferent forms of mitochondrial renewal: (1) total reformation of mito chondria and their content after mitotic division and (2) regeneration of these organelles following high activity, e.g., ATP synthesis.