title: Role of gelsolin interaction with actin in regulation and creation of actin nuclei in chemotactic peptide activated polymorphonuclear neutrophils.
abstract: In vitro Ca++ activates gelsolin to sever F-actin and form a gelsolin-actin (GA) complex at the+end of F-actin that is not dissociated by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) but is separated by EGTA+PIP/PIP2. The gelsolin blocks the+end on the actin filament, but the-end of the filament can still initiate actin polymerization. In thrombin activated platelets, evidence suggests that severing of F-actin by gelsolin increases GA complex, creates one-end actin nucleus and one cryptic+end actin nucleus per cut, and then dissociates to yield free+ends to nucleate rapid actin assembly. We examined the role of F-actin severing in creation and regulation of nuclei and polymerization in polymorphonuclear neutrophils (PMNs). At 2-s intervals after formyl peptide (FMLP) activation of endotoxin free (ETF) PMNs, change in GA complex was correlated with change in+end actin nuclei,-end actin nuclei, and F-actin content. GA complex was quantitated by electrophoretograms of proteins absorbed by antigelsolin from cells lysed in 10 mM EGTA,+end actin nuclei as cytochalasin (CD) sensitive and-end actin nuclei as CD insensitive increases in G-pyrenyl actin polymerization rates induced by the same PMNs, and F-actin content by NBDphallacidin binding to fixed cells. Thirty three percent of gelsolin was in GA complex in basal ETF PMNs; from 2-6 s, GA complexes dissociate (low = 15% at 10 s) and sequentially+end nuclei and F-actin content and then-end nuclei increase to a maximum at 10 s. At > s GA complex increase toward basal and + end nuclei and F-actin content returned toward basal. These kinetic data show gelsolin regulates availability of + end nuclei and actin polymerization in FMLP. However, absence of an initial increase in GA complex or - end nucleating activity shows FMLP activation does not cause gelsolin to sever F- or to bind G-actin to create cryptic + end nuclei in PMNs; the results suggest the + nucleus formation is gelsolin independent.
authors.affiliation: Department of Pediatrics and Cell Biology and Anatomy, University of Alabama, School of Medicine, Birmingham.
authors.forename: J D
authors.initials: JD
authors.lastname: Deaton
authors.forename: T
authors.initials: T
authors.lastname: Guerrero
authors.forename: T H
authors.initials: TH
authors.lastname: Howard
mesh_terms: D000199:Actins / Q000097:blood*; D002135:Calcium-Binding Proteins / Q000097:blood*; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D018260:Gelsolin; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008840:Microfilament Proteins / Q000097:blood*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D013997:Time Factors
chemical_list: D000199:Actins; D002135:Calcium-Binding Proteins; D018260:Gelsolin; D008840:Microfilament Proteins; D009240:N-Formylmethionine Leucyl-Phenylalanine