The role of myosin in vesicle transport during bovine chromaffin cell secretion.
Bovine adrenomedullary cells in culture have been used to study the role of myosin in vesicle transport during exocytosis. Amperometric determination of calcium-dependent catecholamine release from individual digitonin-permeabilized cells treated with 3 microM wortmannin or 20 mM 2,3-butanedione monoxime (BDM) and stimulated by continuous as well as repetitive calcium pulses showed alteration of slow phases of secretion when compared with control untreated cells. The specificity of these drugs for myosin inhibition was further supported by the use of peptide-18, a potent peptide affecting myosin light-chain kinase activity. These results were supported also by studying the impact of these myosin inhibitors on chromaffin granule mobility using direct visualization by dynamic confocal microscopy. Wortmannin and BDM affect drastically vesicle transport throughout the cell cytoplasm, including the region beneath the plasma membrane. Immunocytochemical studies demonstrate the presence of myosin types II and V in the cell periphery. The capability of antibodies to myosin II in abrogating the secretory response from populations of digitonin-permeabilized cells compared with the modest effect caused by anti-myosin V suggests that myosin II plays a fundamental role in the active transport of vesicles occurring in the sub-plasmalemmal area during chromaffin cell secretory activity.
Neco
Patricia
P
Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernández, Campus de San Juan, 03550 Alicante, Spain.
Gil
Anabel
A
Del Mar Francés
María
M
Viniegra
Salvador
S
Gutiérrez
Luis M
LM
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D003931:Diacetyl / Q000031:analogs & derivatives* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000502:physiology; D018613:Microscopy, Confocal; D024462:Myosin Type II / Q000187:drug effects / Q000378:metabolism; D024701:Myosin Type V / Q000187:drug effects / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors; D009218:Myosins / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D022161:Transport Vesicles / Q000378:metabolism*; D000077191:Wortmannin
D000730:Androstadienes; D002395:Catecholamines; D004791:Enzyme Inhibitors; D010455:Peptides; C004717:diacetylmonoxime; D009219:Myosin-Light-Chain Kinase; D024462:Myosin Type II; D024701:Myosin Type V; D009218:Myosins; D003931:Diacetyl; D000077191:Wortmannin