Received for publication June 29, 2004.
Revised December 17, 2004.
Accepted for publication December 17, 2004.

A Novel Class of Fusion Polypeptides Inhibits Exocytosis

Abstract

N-ethylmaleimide sensitive factor (NSF) plays a critical role in the regulation of exocytosis. NSF regulates exocytosis by interacting with a complex containing SNARE molecules, hydrolyzing ATP, and disassembling the SNARE complex. We hypothesized that peptide inhibitors of NSF would decrease exocytosis. We now report the development of a novel set of peptides that block exocytosis by inhibiting NSF activity. These NSF inhibitors are fusion polypeptides composed of an 11 amino acid HIV TAT domain fused to a 22 amino acid NSF domain. These TAT-NSF fusion polypeptides cross endothelial cell membranes, inhibit NSF hydrolysis of ATP, decrease NSF disassembly of SNARE molecules, and block exocytosis of VWF. Control peptides have no effect on exocytosis. TAT-NSF inhibitors administered to mice prolong the bleeding time. Blood concentrations of these TAT-NSF peptides rapidly decrease within 5 min after injection, and then remain constant from 10 min through 60 min after injection. These TAT-NSF compounds may be useful in the treatment of a variety of diseases in which exocytosis plays a prominent role, including myocardial infarction, stroke, thrombosis, and autoimmune disorders.

Key words: Neuropeptides, Thrombin/PAR, Nitric oxide, Nitric oxide synthases, Radical intermediates, Leukocytes/Mast cells, Endocrine cells, Excitotoxicity, neurodegeneration, Exocytosis, Ischemia/Reperfusion