Nature: Four genes that reprogram adult cells into embryonic-like stem cells can also reverse some signs of ageing. The
four genes encode Yamanaka factors, which are essential for embryonic
development, but usually cause tumours when expressed long-term in
animals. Juan Carlos Izpisua Belmonte at the Salk Institute in La Jolla,
California, and his colleagues switched the genes on for two days per
week over several weeks in mice that had an ageing disorder called
progeria. The animals lived about 30
% longer,
and showed improvements in tissue healing and other signs of ageing,
such as organ failure. In normal aged mice, switching on the genes led
to improved recovery from muscle injury and to other signs of
youthfulness. The mice did not develop cancer.
The authors link
the rejuvenation to epigenetic remodelling — changes in the chemical
marks on DNA that do not alter its sequence but influence gene
expression.
