Among the principal obstacles to regenerating spinal cord and brain cells after injury is the “braking” machinery in neurons that prevents regeneration. While peripheral nerves have no such machinery and can readily regenerate, central nervous system (CNS) neurons have their brakes firmly in place and locked. Now, two groups of scientists have independently found a new component of that braking machinery, adding to understanding of the regulation of neuronal regeneration and of possible treatments to switch off the brakes on regrowth of spinal cord or brain tissue. The two groups--one group led by Jong Bae Park, Glenn Yiu, and colleagues from Children’s Hospital Boston and the other led by Sha Mi and colleagues of Biogen Idec, Inc.--discovered that a protein variously called TAJ or TROY acts as an important part of the receptor on neurons that responds to growth-inhibitory molecules in myelin. Specifically, these molecules prevent the growth of the cablelike axons of injured neurons. Myelin is the fatty sheath that encases neurons and acts as an insulator and aid to the transmission of nerve impulses.
