The proteasome and its function in the ageing process

The ageing process is characterized by a progressive loss of function and a decline in the functional capacities of the organism, leading to death. Th e nature of the processes involved in loss of functions is not well underst ood. A number of theories have been proposed, including a hypothesis that e mphasizes the role of reactive oxygen species as a fundamental causal facto r in the ageing process; among other things, oxidative damage to proteins t hrough reactive oxygen species plays a key role in the ageing process. Oxid ative modification of proteins generally causes them to become dysfunctiona l, and normally to undergo preferential degradation. Within the cell the ma in proteolytic machinery involved in the degradation of oxidized proteins i s the proteasomal system, consisting of a multicatalytic protease complex - the proteasome - and numerous regulatory factors. The proteasome is a high ly conserved structure that is distributed in the cytosol, nucleus and endo plasmatic reticulum of mammalian cells. As the proteasome itself is also ex posed to oxidative stress during the ageing process several studies were ca rried out to investigate the role and the activity of the proteasomal syste m during ageing. This review will describe current knowledge of the activit y of the protesomal system and its possible involvement in the ageing proce ss.