Model of Chaperones in Aging

The molecular chaperones, some of which are commonly known as heat-shock proteins, are constitutive and stress-induced proteins participating in cellular “housekeeping” functions including proofreading and folding of macromolecular structures (e.g., proteins, RNA, and DNA), prevention of polymer aggregation, disassembly of misfolded molecules, facilitation of the transport of polymers across biological membranes, and participation in the degradation of ubiquitinated molecules. The expression and function of the molecular chaperones has been linked with life span. The decrease in the constitutive expression and changes in activity and inducibility of chaperones with age contribute to the maintenance of senescence. Conversely, high levels of chaperone expression are associated with an increase in cellular and species longevity as well as in the process of cellular immortalization and the inhibition of cellular apoptosis. Examples are presented to show that the level of chaperone expression and its correlation to cellular and species longevity is subject to variations in response to nutritional, hormetic, chemical, and hormonal conditions. The molecular chaperones are evolution facilitators contributing with important functions that can determine cellular life span as well as the longevity of species.