Researchers have identified a molecule that is involved in muscle ageing, and show that a balance between this and another known factor interferes with regeneration. The work, published online in Nature, suggests that this is a self-imposed inhibition that may have a role in ageing of other organs.
As muscle ages, it gradually loses its ability to repair itself. Irina Conboy and colleagues demonstrate that aged muscle produces high levels of TGF-beta, which leads to overactivation of pSmad3 in muscle stem cells, and show that this blocks regeneration. A molecule, Notch, is known to decrease as muscle ages, and the team shows that the balance between this and Smad3 controls the regenerative abilities of muscle stem cells. Once Notch decreases, the deregulation of the balance in the old muscle interferes with regeneration by regulating proteins that control the cell cycle.
Irina Conboy (University of California at Berkeley, Berkeley, CA, USA)
Abstract available online.
(C) Nature press release.
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