The collagen-binding heat shock protein of molecular weight 47 000 (HSP47), resident in the endoplasmic reticulum (ER), is assumed to play a specific role as a molecular chaperon in the processing of procollagen molecules. The present investigation of age-related alteration in the HSP47 heat response in cultured murine and human fibroblasts revealed expression in cells with a low population doubling level (PDL) derived from young mice and people more inducible by heat treatment than those from older mice and people. On the other hand, cells with a high PDL showed a very low heat response in terms of HSP47 expression regardless of the donor age. Northern blot analysis of HSP47 m-RNA indicated that the age related attenuation of HSP47 expression was regulated by transcriptional mechanisms. Furthermore, immunofluorescent analysis using a monoclonal antibody against the carboxylterminal propeptide of type I procollagen revealed far greater retention of procollagen molecules in the ER lumen of cells from old persons than in those from young persons. This was particularly prominent in heat-treated cells from old persons, indicating the possibility that the observed decrease in HSP47 heat response might cause blockage of procollagen transport to the Golgi and therefore secretion.
All Science Journal Classification (ASJC) codes
- Developmental Biology