Tetanus is caused by tetanus neurotoxin (TeNT), which initially enters motor neurons and then traffics retrogradely into the spinal cord. It is then released from motor neurons, re-enters inhibitory neurons and blocks inhibitory input onto motor neurons, causing involuntary muscle contraction.Thisisinasharpcontrasttobotulinumneurotoxins(BoNTs),whichactwithinmotor neurons to cause the disease botulism. TeNT and BoNTs share the same overall structure/function, yet their distinct trafficking pathways in neurons produce two different diseases. While the pathology is well established, the molecular mechanism underlying the retrogradetransportofTeNTremainselusive. The classic view is that TeNT and BoNTs recognize distinct receptors, and TeNT?s unique receptor mediates its retrograde transport. Recent evidence and our preliminary studies demonstratethatthecell-surfacereceptorisnotinvolvedinthesortingprocess,andtheregion beyondthereceptor-bindingdomainofTeNTisrequiredforsorting.Indeed,thecrystalstructure of TeNT reveals that its protease domain, translocation domain, and receptor-binding domain formuniqueinterfacesatendosomalpHlevels.Thus,weproposeamajorrevisionoftheclassic view: specific interactions among different domains of TeNT are critical for its efficient sorting into the retrograde transport pathway. Here we will test our hypothesis by designing specific mutations that disrupt inter-domain interactions in TeNT and evaluate the activity of these mutanttoxinsonmousemodelsinvivo.Wealsoseektoidentifythekeyhostsortingfactorsthat mediateTeNTretrogradesortingthroughunbiasedglycanarrayscreensandaffinitypurification. Successful completion of our aims will establish a new paradigm in understanding TeNT retrograde transport, and may provide key insights into endosomal sorting and retrograde transport mechanisms in general. Such an understanding will also lay the foundation for developingeffectivetoxin-basedtoolstodelivertherapeuticsintothecentralnervoussystem.

Public Health Relevance

Tetanus neurotoxin (TeNT) causes tetanus, a major infectious disease throughout human history. Here we seek to understand the molecular mechanism underlying the retrograde traffickingofTeNTinneurons,whichisacriticalstepfortoxinaction.Thesestudieswillexpand our current understanding of the endosomal sorting process in general and lay the knowledge basisfordevelopingtoxin--baseddeliverytoolstargetingthecentralnervoussystem.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21NS106159-02
Application #
9673241
Study Section
Synapses, Cytoskeleton and Trafficking Study Section (SYN)
Program Officer
Jett, David A
Project Start
2018-04-01
Project End
2020-09-30
Budget Start
2019-04-01
Budget End
2020-09-30
Support Year
2
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Boston Children's Hospital
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
02115