Botulinumneurotoxinsareafamilyofsevenbacterialtoxins(BoNT/A-G).MembersoftheBoNT family have been widely utilized for treating a growing list of medical conditions. During our previous funding cycle, we carried out the first comprehensive investigation of the effect of BoNTsonsurvivalofneurons.Weidentifiedtwoofthetoxins,BoNT/CandBoNT/E,thatinduce death of neurons. We further established that neuronal death is due to blockage of a plasma membrane recycling process by BoNT/C and E. These findings open a new line of inquiry on toxinbiologyandrevealanovelmembranerecyclingprocessessentialforneuronsurvival. Followingthesefindings,wefurtherfoundthatamyloidprecursorprotein(APP)isamajorcargo ofthemembranerecyclingprocessblockedbyBoNTs.Hereweproposemechanisticstudiesto elucidate this essential membrane recycling process at the molecular level. We will also utilize BoNTs as a novel tool to address key questions about APP recycling/processing and explore the potential role of APP in BoNT action at nerve terminals. Finally, our current studies established that SNAP-25, which is cleaved by BoNT/A, C, and E, is essential for neuron survival and APP recycling. This finding raised a significant safety concern regarding long-term useofthemajortherapeutictoxinBoNT/A,whichpromptedustodevelopalternativetherapeutic toxinsthroughproteinengineering. Our proposed studies will provide a mechanistic understanding of the effect of BoNTs on survival of neurons and may yield novel insights into APP biology. They will also address concerns about the long-term safety of current therapeutic toxins and aim to develop a new generationoftherapeutictoxinswithimprovedefficacyandsafetyinhumans.

Public Health Relevance

Botulinum neurotoxins (BoNTs) are widely used to treat a growing list of medical conditions. Members of the BoNT family cause the death of neurons by blocking a plasma membrane recycling pathway. Here we seek to gain a mechanistic understanding of this critical pathway (which also contains the amyloid precursor protein involved in Alzheimer disease) and we also aimtodevelopanewgenerationoftherapeutictoxinswithimprovedefficacyinhumans.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Biophysics of Neural Systems Study Section (BPNS)
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Jett, David A
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Boston Children's Hospital
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