Potentiation of calcium levels by extracellular arachidonic acid in nuclei isolated from macrophages stimulated with receptor-recognized forms of alpha(2)-macroglobulin.
Ligation of macrophage alpha(2)-macroglobulin signalling receptors (alpha(2)MSR) with activated alpha(2)-macroglobulin (alpha(2)M*) increases intracellular Ca(2+), and cytosolic phospholipase A(2) (cPLA(2)) and phospholipase D activities. In view of the relationship between cellular Ca(2+) and mitogenesis, we examined the effect of the product of cPLA(2) activity, arachidonic acid (AA), on nuclear Ca(2+) levels in macrophages stimulated with alpha(2)M*, platelet derived growth factor, and bradykinin. AA addition increased Ca(2+) levels in Fura-2/AM loaded nuclei from both buffer-treated and agonist-stimulated cells, but the increase in stimulated macrophages was 2-4-fold higher. Preincubation of Fura-2/AM loaded nuclei with EGTA or BAPTA/AM abolished AA-induced increase in nuclear Ca(2+) levels. Preincubation of nuclei with indomethacin did not affect AA-induced increase in nuclear Ca(2+) in agonist-stimulated nuclei. It is concluded that in macrophages stimulated with various agonists, AA, derived from cPLA(2)-dependent hydrolysis of phospholipids, plays a significant role in regulating nuclear Ca(2+) levels and thus nuclear functions.
Misra
U K
UK
Department of Pathology, Box 3712, Duke University Medical Center, Durham, NC 27710, USA.
Gawdi
G
G
Pizzo
S V
SV
D016718:Arachidonic Acid / Q000494:pharmacology*; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002467:Cell Nucleus / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003593:Cytoplasm / Q000201:enzymology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D007213:Indomethacin / Q000494:pharmacology; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D008264:Macrophages / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D010739:Phospholipase D / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011971:Receptors, Immunologic / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D019284:Thapsigargin / Q000494:pharmacology; D000511:alpha-Macroglobulins / Q000494:pharmacology*
D002614:Chelating Agents; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D010982:Platelet-Derived Growth Factor; D011971:Receptors, Immunologic; D000511:alpha-Macroglobulins; C049925:fura-2-am; D016718:Arachidonic Acid; D004533:Egtazic Acid; D019284:Thapsigargin; D010741:Phospholipases A; D010739:Phospholipase D; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D001920:Bradykinin; D002118:Calcium; D016257:Fura-2; D007213:Indomethacin