Defective chemoattractant-induced calcium signalling in S100A9 null neutrophils.
The S100 family member S100A9 and its heterodimeric partner, S100A8, are cytosolic Ca2+ binding proteins abundantly expressed in neutrophils. To understand the role of this EF-hand-containing complex in Ca2+ signalling, neutrophils from S100A9 null mice were investigated. There was no role for the complex in buffering acute cytosolic Ca2+ elevations. However, Ca2+ responses to inflammatory agents such as chemokines MIP-2 and KC and other agonists are altered. For S100A9 null neutrophils, signalling at the level of G proteins is normal, as is release of Ca2+ from the IP(3) receptor-gated intracellular stores. However MIP-2 and FMLP signalling in S100A9 null neutrophils was less susceptible than wildtype to PLCbeta inhibition, revealing dis-regulation of the signalling pathway at this level. Downstream of PLCbeta, there was reduced intracellular Ca2+ release induced by sub-maximal levels of chemokines. Conversely the response to FMLP was uncompromised, demonstrating different regulation compared to MIP-2 stimulation. Study of the activity of PLC product DAG revealed that chemokine-induced signalling was susceptible to inhibition by elevated DAG with S100A9 null cells showing enhanced inhibition by DAG. This study defines a lesion in S100A9 null neutrophils associated with inflammatory agonist-induced IP3-mediated Ca2+ release that is manifested at the level of PLCbeta.
McNeill
E
E
Leukocyte Adhesion Laboratory, Cancer Research UK London Research Institute (CRUK LRI), 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
Conway
S J
SJ
Roderick
H L
HL
Bootman
M D
MD
Hogg
N
N
D000818:Animals; D020013:Calcium Signaling; D040502:Calgranulin B / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D054426:Chemokine CXCL2; D018925:Chemokines / Q000494:pharmacology; D002630:Chemotactic Factors / Q000494:pharmacology*; D004075:Diglycerides / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D006706:Homeostasis; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D040502:Calgranulin B; D054426:Chemokine CXCL2; D018925:Chemokines; D002630:Chemotactic Factors; C404915:Cxcl2 protein, mouse; D004075:Diglycerides; D004963:Estrenes; D053496:Inositol 1,4,5-Trisphosphate Receptors; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D009240:N-Formylmethionine Leucyl-Phenylalanine; C049813:N-formylmethionyl-leucyl-phenylalanyl-lysine; D010738:Type C Phospholipases