Does actin polymerization status modulate Ca2+ storage in human neutrophils? Release and coalescence of Ca2+ stores by cytochalasins.
The aim of this paper was to establish whether actin polymerization modulated cytosolic Ca2+ storage in human neutrophils. Over the concentration ranges which inhibit actin polymerization, cytochalasins A, B, and D liberated Ca2+ from membrane-bound stores within neutrophils. Two Ca2+ storage sites were identified in neutrophils by the accumulation of the Ca2+ binding probe, chlortetracycline: one at the center of the cell and the other at the cell periphery. Confocal imaging demonstrated that cytochalasins released Ca2+ from the neutrophil periphery, but not from the central Ca2+ store. Ca2+ store release was coupled to Ca2+ influx, suggesting that the peripheral site may be a physiological store containing a Ca2+ influx factor. 3,3'-Dihexyloxacarbocyanine iodide staining organelles, which correlate with Ca2+ release sites, coalesced in neutrophils after treatment with cytochalasins. We propose that peripheral Ca2+ storage sites are restricted from coalescence by cortical polymerized actin and that Ca2+ store coalescence and Ca2+ release are coupled events.
Al-Mohanna
F A
FA
Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
Pettit
E J
EJ
Hallett
M B
MB
D000199:Actins / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002232:Carbocyanines; D002614:Chelating Agents / Q000494:pharmacology; D002751:Chlortetracycline / Q000494:pharmacology; D003572:Cytochalasins / Q000494:pharmacology*; D003600:Cytosol / Q000378:metabolism; D005456:Fluorescent Dyes; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases; D011108:Polymers; D051381:Rats
D000199:Actins; D002232:Carbocyanines; D002614:Chelating Agents; D003572:Cytochalasins; D005456:Fluorescent Dyes; D007476:Ionophores; D011108:Polymers; C007392:3,3'-dihexyl-2,2'-oxacarbocyanine; D015759:Ionomycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D011065:Poly(ADP-ribose) Polymerases; D001905:Botulinum Toxins; C096324:botulinum toxin type C; D002118:Calcium; D002751:Chlortetracycline