Nogo makes cord regrowth a no go.

During this year's Super Bowl, a commercial used computer-generated special effects to show Christopher Reeve walking again in the future. While the actor wanted the ad to bring hope to other paralyzed people, some critics chided him for being overly optimistic about the current state of research into spinal cord regeneration. Indeed, scientists are still struggling to understand why cords won't regrow.

In the Feb. 4 SCIENCE, three research teams report their identification of a gene for a protein that inhibits the regrowth of nerves in the spinal cord. The protein, called Nogo, is present in the cord's myelin, the fatty sheath that insulates nerve-cell extensions called axons. An antibody to Nogo, created even before researchers fully characterized the protein, encourages some axon regrowth in rodents with spinal cord injuries.

With the full protein and its gene in hand, scientists expect they will be able to identify exactly which part of Nogo stops axons from growing. This should allow them to create better ways of blocking the effect. The researchers caution, however, that spinal cord myelin contains several inhibitory molecules. Simultaneously countering Nogo and these other axon-growth blockers should spur the most cord regeneration, they suggest.