title: Scanning electron microscopy study of neutrophil membrane tubulovesicular extensions (cytonemes) and their role in anchoring, aggregation and phagocytosis. The effect of nitric oxide.
abstract: We have shown that human neutrophils develop dynamic thin and very long tubulovesicular extensions (cytonemes) upon adhesion to fibronectin, if cell spreading was blocked by Na(+)-free medium or by 4-bromophenacyl bromide, N-ethylmaleimide, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole and cytochalasin D (S. I. Galkina, G. F. Sud'ina and V. Ullrich, (2001). Exp. Cell Res. 266, 222-228). In the present work we found that similar in size and behavior tubulovesicular extensions were formed on the neutrophil cell bodies upon adhesion to fibronectin-coated substrata in the presence of the nitric oxide donor diethylamine NONOate. In the presence of the nitric oxide synthase inhibitor N-omega-nitro-L-arginine methyl ester, neutrophils were well spread and had no microextensions. Using scanning electron microscopy, we demonstrated that tubulovesicular extensions of neutrophils executed long-range adhesion and binding objects for phagocytosis, such as serum-opsonized zymosan particles and erythrocytes. Tubulovesicular extensions anchored neutrophils to substrata in a beta1 and beta2 integrin-independent, but L-selectin-dependent manner. BODIPY-sphingomyelin impaired development of tubulovesicular extension, and heparitinase 1 played a role in their destruction. Membrane tubulovesicular extensions are supposed to represent protrusions of an intracellular exocytotic traffic and serve as cellular sensory and adhesive organelles. Nitric oxide seems to play a role in regulation of tubulovesicular extensions formation, thus affecting neutrophil adhesive interactions and phagocytosis.
authors.affiliation: A. N. Belozersky Institute of Physico-Chemical Biology of the M. V. Lomonosov Moscow State University, 119992, Moscow, Leninskie gory, Building A, Moscow, Russia. galkina@genebee.msu.ru
authors.forename: Svetlana I
authors.initials: SI
authors.lastname: Galkina
authors.forename: Julian G
authors.initials: JG
authors.lastname: Molotkovsky
authors.forename: Volker
authors.initials: V
authors.lastname: Ullrich
authors.forename: Galina F
authors.initials: GF
authors.lastname: Sud'ina
mesh_terms: D001896:Boron Compounds / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002449:Cell Aggregation / Q000187:drug effects / Q000502:physiology; D022081:Cell Surface Extensions / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis / Q000502:physiology; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D009569:Nitric Oxide / Q000494:pharmacology / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D015388:Organelles / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase