Expression of endothelin, fibronectin, and mortalin as aging and mortality markers.
Studies on fibronectin, endothelin-1, and mortalin from our laboratory are reviewed here. Fibronectin expression has been analyzed as upregulated during in vitro serial passaging of human fetal lung and neonatal foreskin fibroblasts as well as umbilical vein endothelial cells. In vivo aging of skin fibroblasts, as well as aortic endothelial cells, are also accompanied by upregulation of fibronectin expression. Fibronectin promoter binding proteins from young and old cell nuclear extracts were further explored by gel retardation assay. Preliminary analyses have detected age-related differential binding activities with respect to AP-1, CRES, TFIID, CTF, and AP-2 regions, whereas Sp1 binding proteins remain unaltered. Endothelin-1 expression is also seen as upregulated during in vitro and in vivo aging of endothelial cells. This can contribute to the hypertension commonly observed in elderly patients. Mortalin, a novel member of hsp 70 family of proteins, was initially identified by virtue of its association with a cellular mortal phenotype. Subsequently, normal cells and the ones with an immortal phenotype have been found to have differential subcellular localization of this protein. Antiproliferative activity of this protein in normal cells and the deregulation of expression in transformed cells is observed which suggests the association of mortalin in pathways that determine cellular divisional phenotype.