Robo-4 and Slit2 May Team Up Against Wet AMD

by Dan Roberts
March 17, 2008
“Robo-4” sounds like a movie by Arnold Schwarzenegger, but in this case, it is a link to another potential treatment for wet AMD.
Short for “Roundabout,” Robo-4 is a protein receptor found on the surface of blood vessel cells. When it binds with another protein called Slit2, the combination stops blood vessel growth (angiogenesis). This is a natural “braking” action on the normally beneficial process of healing. Blood vessels carry needed nutrition to unhealthy parts of the body, but their development must be kept under control.
If Robo-4 is deficient, the vascular endothelial growth factor (VEGF) that initiates angiogenesis will not be blocked. New vessels, therefore, will continue to grow unabated, often leaking and causing damage. Injecting Slit2 into Robo-4 deficient rodents has been shown to inhibit VEGF activity.
These new findings were reported in the March 16, 2008 online edition of Nature Medicine. (Lead author: Dean Y. Li, M.D., Ph.D., H. A., University of Utah, Salt Lake City UT.)
There is a difference between this therapy and anti-angiogenic drugs currently in use. Instead of blocking VEGF, injection of Slit2 activates a signal to the cells to block the VEGF themselves. This new mechanism may prove to be effective alternative treatment for wet AMD. Years of study, however, lie ahead before it can be applied in practice to humans.