Scientists probe the genetics of ageing

A genetic driver of the ageing process has been discovered by creating cells that mimic Werner's syndrome, a very rare disease that causes premature ageing.

Scientists from the US and China found that the way DNA is packaged within cells was altered in people affected by Werner's.

'Our findings show that the gene mutation that causes Werner syndrome results in the disorganization of heterochromatin, and that this disruption of normal DNA packaging is a key driver of ageing,' said Professor Juan Carlos Izpisua Belmonte, a senior author on the paper, which was published in Science.

Werner's syndrome is caused by a defective or missing version of a gene called WRN - those affected succumb to age-related diseases such as cataracts, type 2 diabetes and cancer early in life. The team from the Salk Institute in California and the Chinese Academy of Sciences used human embryonic stem cells that were not affected by Werner's syndrome, and snipped out two gene segments from the WRN gene, mimicking the effect of the disease.

This allowed the scientists to observe what happens early on in the ageing process of cells affected by Werner's. Normally, DNA is folded very tightly in a formation called heterochromatin. But in cells with a defective WRN gene, they found that the DNA was folded much more loosely.

The team then compared these cells with those from six young and six middle-aged and elderly people without Werner's, and found that the stem cells of the older group showed DNA packaging problems similar to those in the Werner group.

'Our finding has implications beyond Werner syndrome, as it identifies a central mechanism of ageing - heterochromatin disorganisation - which has been shown to be reversible,' Professor Belmonte said.

Rick Horwitz, executive director of the Allen Institute for Cell Science, was impressed with the work. He told the Washington Post: 'This is a beautiful example of how genomics, human stem cells and the new gene-editing technologies conjoin to provide major insights into human disease. This is an early example of what I suspect will be a very large number of similar kinds of studies.'