Abstract
When fused with the protein transduction domain (PTD) derived from the human immunodeficiency virus TAT protein, proteins can cross the blood–brain barrier and cell membrane and transfer into several tissues, including the brain, making protein therapy feasible for various neurological disorders. We have constructed a powerful antiapoptotic modified Bcl‐X~L~ protein (originally constructed from Bcl‐X~L~) fused with PTD derived from TAT (TAT‐modified Bcl‐X~L~), and, to examine its clinical effectiveness in a mouse model of familial amyotrophic lateral sclerosis (ALS), transgenic mice expressing human Cu/Zn superoxide dismutase (SOD1) bearing a G93A mutation were treated by intrathecal infusion of TAT‐modified Bcl‐X~L~. We demonstrate that intrathecally infused TAT‐fused protein was effectively transferred into spinal cord neurons, including motor neurons, and that intrathecal infusion of TAT‐modified Bcl‐X~L~ delayed disease onset, prolonged survival, and improved motor performance. Histological studies show an attenuation of motor neuron loss and a decrease in the number of cleaved caspase 9‐, cleaved caspase 3‐, and terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labeling (TUNEL)‐positive cells in the lumbar cords of TAT‐modified Bcl‐X~L~‐treated G93A mice. Our results indicate that intrathecal protein therapy using a TAT‐fused protein is an effective clinical tool for the treatment of ALS. © 2008 Wiley‐Liss, Inc.