But it's still a mystery why the body breaks down as it gets older. Now, using a hot new technology, researchers are finally finding genes that make cells show their age. DNA microarrays, also called DNA chips, have stoked excitement in the research community because they can test the activity of many genes at once. To find out what's going on inside a cell, researchers expose the chip to fluorescently labeled genetic material that's being shipped around inside the cell.
Active genes leave telltale traces where they match up with mapped locations on the chip.
A team led by Richard Lerner and Peter Schultz of The Scripps Research Institute in La Jolla, California, used microarrays to analyze gene activity in fibroblasts, the cells that help form skin and connective tissues. They tested cells from healthy people of various ages and also from children with Hutchinson-Guilford progeria, a rare hereditary disorder that resembles an accelerated form of aging. Many of the same changes also occurred in the fibroblasts from the progeria patients, a finding that indicates that these individuals are indeed aging abnormally fast, they report in the 31 March Science . Of the age-dependent genes, several are known to help cells divide, providing support for the notion that aging interrupts cell division. It will take more work to confirm that these genes are also differentially active in aging people and not just differently aged cell lines, says aging specialist Leonard Guarente of the Massachusetts Institute of Technology.