Botulinum neurotoxins are a family of seven bacterial toxins (BoNT/A-G) that cause the disease botulism in humans and animals. They target neurons and cleave host proteins required for synaptic vesicle exocytosis, thereby blocking synaptic transmission and paralyzing the hosts. This mode of action and its role in pathogenesis has been well established. Humans used to get exposed to BoNTs mainly via food poisoning, but significant changes have occurred in human- BoNT interactions. First, medical advances can now revive previously untreatable patients from acute BoNT actions. Second, BoNTs are utilized as therapeutics to target neurons via local injections over long periods of time. These changes have raised the critical need to examine the additional long-term consequences of exposure to BoNTs. Indeed, previous reports and our preliminary studies have revealed that a subset of BoNTs may induce degeneration of cultured rodent neurons in addition to blocking synaptic vesicle exocytosis.
In Aim 1, we will examine whether BoNTs may induce degeneration of human neurons and in in vivo rodent models that mimic therapeutic applications. We will also investigate whether human genetic variations might render certain populations susceptible to potential cytotoxicity from the major therapeutic toxin BoNT/A.
In Aim 2, we will examine our hypothesis that BoNTs induce neurodegeneration because their substrates play an essential role in maintaining the membrane balance at plasma membranes.
Aim 1 will provide a solid foundation for establishing the potential clinical relevance.
Aim 2 will provide a mechanistic understanding for BoNT cytotoxicity. Together, these studies will establish neuronal cytotoxicity as a """"""""newly emerged"""""""" long-term consequence due to changes in BoNT-human interactions, with significant implications for understanding long-term effects of botulism in patients and for ensuring the safety of using BoNTs as therapeutic toxins.

Public Health Relevance

Botulinum neurotoxins are one of the most dangerous potential bioterrorism agents and are also used as therapeutics. They are well-known for their ability to block synaptic vesicle exocytosis, but it has remained controversial whether members of botulinum neurotoxins might also induce neurodegeneration. Here we will investigate the potential cytotoxicity of botulinum neurotoxins and understand its mechanism, with the goal to establish the long-term consequences of BoNT action and to ensure the safety of toxin therapeutic applications.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS080833-02
Application #
8617314
Study Section
Host Interactions with Bacterial Pathogens Study Section (HIBP)
Program Officer
Jett, David A
Project Start
2013-03-01
Project End
2018-02-28
Budget Start
2014-03-01
Budget End
2015-02-28
Support Year
2
Fiscal Year
2014
Total Cost
$723,516
Indirect Cost
$310,078
Name
Harvard University
Department
Veterinary Sciences
Type
Schools of Medicine
DUNS #
047006379
City
Boston
State
MA
Country
United States
Zip Code
02115
Masuyer, Geoffrey; Zhang, Sicai; Barkho, Sulyman et al. (2018) Structural characterisation of the catalytic domain of botulinum neurotoxin X - high activity and unique substrate specificity. Sci Rep 8:4518
Chen, Peng; Tao, Liang; Wang, Tianyu et al. (2018) Structural basis for recognition of frizzled proteins by Clostridium difficile toxin B. Science 360:664-669
Zhang, Sicai; Lebreton, Francois; Mansfield, Michael J et al. (2018) Identification of a Botulinum Neurotoxin-like Toxin in a Commensal Strain of Enterococcus faecium. Cell Host Microbe 23:169-176.e6
Zhang, Sicai; Berntsson, Ronnie P-A; Tepp, William H et al. (2017) Structural basis for the unique ganglioside and cell membrane recognition mechanism of botulinum neurotoxin DC. Nat Commun 8:1637
Chevalier, Aaron; Silva, Daniel-Adriano; Rocklin, Gabriel J et al. (2017) Massively parallel de novo protein design for targeted therapeutics. Nature 550:74-79
Zhang, Sicai; Masuyer, Geoffrey; Zhang, Jie et al. (2017) Identification and characterization of a novel botulinum neurotoxin. Nat Commun 8:14130
Tao, Liang; Zhang, Jie; Meraner, Paul et al. (2016) Frizzled proteins are colonic epithelial receptors for C. difficile toxin B. Nature 538:350-355
Yao, Guorui; Zhang, Sicai; Mahrhold, Stefan et al. (2016) N-linked glycosylation of SV2 is required for binding and uptake of botulinum neurotoxin A. Nat Struct Mol Biol 23:656-62
Peng, Lisheng; Adler, Michael; Demogines, Ann et al. (2014) Widespread sequence variations in VAMP1 across vertebrates suggest a potential selective pressure from botulinum neurotoxins. PLoS Pathog 10:e1004177
Lee, Kwangkook; Zhong, Xiaofen; Gu, Shenyan et al. (2014) Molecular basis for disruption of E-cadherin adhesion by botulinum neurotoxin A complex. Science 344:1405-10

Showing the most recent 10 out of 13 publications