Cell Aging: A Model System Approach

Abstract

Although there is a large literature describing age-related physiological changes at the cell, tissue, organ, and organism level, fundamental questions about the aging process remain unanswered. In fact, it can be said that the experimental design required to answer them is in many ways obscure. For example, we still need answers to such questions as: (1) is aging intrinsic or extrinsic to the organism; (2) is aging intrinsic to an individual cell or an integrated function; (3) are there mechanisms which control the rate of aging; (4) is there a kind of pacemaker cell that signals the rest of the cells to degenerate and die, or does each cell have its own clock-like machinery by which aging proceeds; and (5) in either case, would such a clock mechanism be contained in the nucleus or in the cytoplasm? Definitive answers to all these questions must precede elucidation of the biology of aging.