EXPRESSION ANALYSIS OF MORTALIN, A UNIQUE MEMBER OF THE HSP70 FAMILY OF PROTEINS, IN RAT-TISSUES

We have investigated the expression of mortalin in rat tissues by Nort hern analysis, RNA in situ hybridization, and immunohistochemical stud ies. By Northern assay, the highest level of expression was detected i n brain, heart, and skeletal muscle followed by lung, liver, and kidne y, and the least level of expression was detected in testis and spleen . RNA in situ and immunohistochemical studies showed that mortalin exp ression is significantly higher in upper nondividing layers than in th e lower basal layers of skin, in neurons and nerve fibers than in surr ounding glial cells in brain, in cardiomyocytes than in nonmyocytes in heart, and in interstitial secretory tissue than in germinating folli cles in ovary. Such tissue- and cell-specific expression patterns of m ortalin coordinates with its earlier reported anti-proliferative funct ion in normal cells. However, a deregulation of the expression is obse rved in rat brain tumor along with the detection of nonpancytosolic mo rtalin in rat glioma cell line C6. The study suggests that mortalin is involved in pathways that regulate division capacities of cells in vi vo. (C) 1997 Academic Press.