Justin M. Blasi

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Neurotransmitter release is potently blocked by a group of structurally related toxin proteins produced by Clostridium botulinum. Botulinum neurotoxin type B (BoNT/B) and tetanus toxin (TeTx) are zinc-dependent proteases that specifically cleave synaptobrevin (VAMP), a membrane protein of synaptic vesicles. Here we report that inhibition of transmitter(More)
The anaerobic bacterium Clostridium botulinum produces several related neurotoxins that block exocytosis of synaptic vesicles in nerve terminals and that are responsible for the clinical manifestations of botulism. Recently, it was reported that botulinum neurotoxin type B as well as tetanus toxin act as zinc-dependent proteases that specifically cleave(More)
Clostridial neurotoxins, tetanus toxin (TeTx) and the seven related but serologically distinct botulinal neurotoxins (BoNT/A to BoNT/G), are potent inhibitors of synaptic vesicle exocytosis in nerve endings. Recently it was reported that the light chains of clostridial neurotoxins act as zinc-dependent metalloproteases which specifically cleave synaptic(More)
Tetanus toxin (TeTx) and the various forms of botulinal neurotoxins (BoNT/A to BoNT/G) potently inhibit neurotransmission by means of their L chains which selectively proteolyze synaptic proteins such as synaptobrevin (TeTx, BoNT/B, BoNT/F), SNAP-25 (BoNT/A), and syntaxin (BoNT/C1). Here we show that BoNT/D cleaves rat synaptobrevin 1 and 2 in toxified(More)
Syntaxin 1 has been shown to play an outstanding role in synaptic vesicle exocytosis. Two isoforms of this protein are expressed in neurons, syntaxin 1A and 1B. However, the physiological significance of the occurrence of such closely related isoforms is not still understood. Here, by means of isoform-specific immunocytochemistry, we show that syntaxin 1A(More)
To understand the molecular basis of exocytosis in human neutrophils, the role of syntaxin 6 and SNAP-23 in neutrophil degranulation was examined. Human syntaxin 6 was cloned and identified as a 255-amino acid protein with a carboxy-terminal transmembrane region and two coiled-coil domains. Syntaxin 6 was localized mainly in the plasma membrane of human(More)
SNAP-25 and Rab3A were originally identified as synaptic proteins involved in neuronal membrane traffic. Recently, both proteins have been detected in several mammalian endocrine cell types and have been proposed as essential components of the exocytotic pathway in neuroendocrine cells. In this study, the expression of SNAP-25 and Rab3A was analysed in(More)
he arrest of axonal transport by colchicine administration has been extensively used in immunocytochemical studies to increase the levels of neuroactive compounds in neuronal somata. In order to study the accumulation rates of a variety of proteins with location and physiological action at the synaptic terminal, we analysed, by immunocytochemical methods,(More)
Electrophysiological, morphological, and biochemical approaches were combined to study the effect of the presynaptic injection of the light chain of botulinum toxin C1 into the squid giant synapse. Presynaptic injection was accompanied by synaptic block that occurred progressively as the toxin filled the presynaptic terminal. Neither the presynaptic action(More)
Dystrophic neurites are major components of neuritic (both immature and mature) senile plaques in Alzheimer disease. Previous studies have shown strong immunoreactivity for different neuropeptides, and chromogranin A, a protein associated with dense-core vesicles, in dystrophic neurites. In the present study, antibodies to synaptophysin, synapsin, Rab3a and(More)