title: Metabolic regulation of neutrophil spreading, membrane tubulovesicular extensions (cytonemes) formation and intracellular pH upon adhesion to fibronectin.
abstract: Circulating leukocytes have a round cell shape and roll along vessel walls. However, metabolic disorders can lead them to adhere to the endothelium and spread (flatten). We studied the metabolic regulation of adhesion, spreading and intracellular pH (pHi) of neutrophils (polymorphonuclear leukocytes) upon adhesion to fibronectin-coated substrata. Resting neutrophils adhered and spread on fibronectin. An increase in pHi accompanied neutrophil spreading. Inhibition of oxidative phosphorylation or inhibition of P- and F-type ATPases affected neither neutrophil spreading nor pHi. Inhibition of glucose metabolism or V-ATPase impaired neutrophil spreading, blocked the increase in the pHi and induced extrusion of membrane tubulovesicular extensions (cytonemes), anchoring cells to substrata. Omission of extracellular Na(+) and inhibition of chloride channels caused a similar effect. We propose that these tubulovesicular extensions represent protrusions of exocytotic trafficking, supplying the plasma membrane of neutrophils with ion exchange mechanisms and additional membrane for spreading. Glucose metabolism and V-type ATPase could affect fusion of exocytotic trafficking with the plasma membrane, thus controlling neutrophil adhesive state and pHi. Cl(-) efflux through chloride channels and Na(+) influx seem to be involved in the regulation of the V-ATPase by carrying out charge compensation for the proton-pumping activity and through V-ATPase in regulation of neutrophil spreading and pHi.
authors.affiliation: A. N. Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, 119992 Leninskie gory, Bldg. A, Moscow, Russia. galkina@genebee.msu.su
authors.forename: Svetlana I
authors.initials: SI
authors.lastname: Galkina
authors.forename: Galina F
authors.initials: GF
authors.lastname: Sud'ina
authors.forename: Thomas
authors.initials: T
authors.lastname: Klein
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D022081:Cell Surface Extensions / Q000378:metabolism*; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D000242:Cyclic AMP / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism*; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008954:Models, Biological; D009504:Neutrophils / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D010085:Oxidative Phosphorylation / Q000187:drug effects; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors; D012964:Sodium / Q000378:metabolism; D012966:Sodium Cyanide / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors
chemical_list: D018118:Chloride Channels; D005353:Fibronectins; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride; D012964:Sodium; D000242:Cyclic AMP; D006180:Proton-Translocating ATPases; D012966:Sodium Cyanide