A recent study carried out in the Scripps Research Institute in California, and reported in Science for March 31, focuses on the gene changes which occur in ageing fibroblasts. These are of outstanding importance for the health of skin and connective tissues. There is evidence that in advancing age the machinery required for normal separation of chromosomes during cell division produces genetic instability and a variety of disturbances of gene function.
The study found that expression of 61 genes of a total of some 6,300 altered with advancing age, and similar changes were observed in patients suffering from the rare inherited disorder Hutchinson-Gilford progeria in whom the ageing process appears to be accelerated. Sufferers from progeria often die in their early teens from conditions such as heart disease which are usually associated with elderly individuals.
Several fibroblast genes showing altered expression patterns are concerned with formation of collagen and other proteins of the extracellular matrix. They are also involved in inflammatory processes, including heart disease and Alzheimer's disease. At the same time, some 15 genes that help control mitosis are suppressed. The loss of genes which suppress tumour growth, or activation of genes which promote it, contributes to the incidence of cancer in old age.
Viewed from this standpoint, ageing may be regarded as predominantly a disease involving the mismanagement of cell division. Moreover, it is suggested that different gene changes underlie the ageing of different tissues. The declining activity of many genes impairs energy production and synthesis of proteins, lipids and other essential cell constituents, thereby weakening muscle power and producing stress proteins to repair or eliminate damaged DNA.