A critical role for N-ethylmaleimide-sensitive fusion protein (NSF) in platelet granule secretion.
The molecular mechanisms that regulate membrane targeting/fusion during platelet granule secretion are not yet understood. N-ethylmaleimide-sensitive fusion protein (NSF), soluble NSF attachment proteins (SNAPs), and SNAREs (SNAP receptors) are elements of a conserved molecular machinery for membrane targeting/fusion that have been detected in platelets. We examined whether NSF, an ATPase that has been shown to play a critical role in membrane targeting/fusion in many cell types, is necessary for platelet granule secretion. Peptides that mimic NSF sequence motifs inhibited both alpha-granule and dense-granule secretion in permeabilized human platelets. This inhibitory effect was sequence-specific, because neither proteinase K-digested peptides nor peptides containing similar amino acids in a scrambled sequence inhibited platelet secretion. The peptides that inhibited platelet granule secretion also inhibited the human recombinant alpha-SNAP-stimulated ATPase activity of recombinant NSF. It was also found that anti-NSF antibodies, which inhibited recombinant alpha-SNAP-stimulated ATPase activity of NSF, inhibited platelet granule secretion in permeabilized cells. The inhibition by anti-NSF antibodies was abolished by the addition of recombinant NSF. These data provide the first functional evidence that NSF plays an important role in platelet granule secretion.
Polgár
J
J
Harvard School of Public Health, Cardiovascular Biology Laboratory, Boston, MA, USA.
Reed
G L
GL
D000595:Amino Acid Sequence; D001792:Blood Platelets / Q000502:physiology* / Q000648:ultrastructure; D002352:Carrier Proteins / Q000494:pharmacology / Q000502:physiology*; D015550:Cell Degranulation / Q000187:drug effects / Q000502:physiology*; D003594:Cytoplasmic Granules / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008969:Molecular Sequence Data; D052066:N-Ethylmaleimide-Sensitive Proteins; D010455:Peptides / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D010455:Peptides; D011994:Recombinant Proteins; D033921:Vesicular Transport Proteins; D052066:N-Ethylmaleimide-Sensitive Proteins