Determinants of cellular age

Reduced function of a family of membrane transporters may play a role in replicative ageing in yeast cells, reports a paper online in Nature Cell Biology. The study also suggests that this protein family may influence cellular ageing in multicellular organisms.

Just like most cells in our bodies, budding yeast cells can only divide 20-30 times. However, what limits their so called 'replicative age' has remained unknown. Li and colleagues found that some multidrug resistance (MDR) proteins are inherited differently between the mother and the newly budded daughter cell. Whereas the newly produced proteins go to the daughter, the old pool remains attached to the mother. This could, over time, lead to reduced amounts and/or activities of MDR proteins as the mother cell 'ages'. Indeed, the authors show that the activity of a polyamine transporter is reduced in older cells. As these proteins are important to maintain the health of the cell, such a decline could influence cellular lifespan.

In accordance with this idea, the group also finds that yeast mutants lacking some MDR genes show faster replicative ageing, whereas the introduction of an extra copy of these genes extends replicative lifespan.