Inhibition of Axotomy-induced Neuronal Apoptosis by Extracellular Delivery of a Bcl-XL Fusion Protein

Bcl-2 and Bcl-XL prevent neuronal apoptosis during development, neurodegenerative disease, and trauma. To test a new anti-apoptosis strategy for neuroprotection, we engineered nontoxic components of anthrax toxin into a Bcl-XL delivery system. Delivery of Bcl-XL by this system prevented apoptosis of cultured rat cerebellar granule cells and macrophages, and the prevention depended on both the Bcl-XL and the anthrax toxin receptor binding/translocation moieties. Furthermore, neuronal death in vivo in a retinal ganglion cell model of axotomy-induced apoptosis was inhibited by administration of this fusion protein. Thus, Bcl-XL protein can be delivered into cells from the medium or interstitial space, offering a new way to block apoptosis upstream of many caspases and the mitochondria dysfunction phase of apoptosis.