Sphingosine-1-phosphate receptors stimulate macrophage plasma-membrane actin assembly via ADP release, ATP synthesis and P2X7R activation.
Eukaryotic plasma membranes assemble actin filaments within seconds of activation of many receptors, especially during chemotaxis. Here, serum or sphingosine-1-phosphate stimulation of J774 and RAW macrophages released ADP within seconds into the extracellular medium, along with an adenylate kinase activity that converted ADP to ATP. ATP then activated the P2X7 receptor (P2X7R) that was necessary for a peak of plasma-membrane actin assembly within 5 to 10 seconds in P2X7R-expressing J774, RAW and primary macrophages. Neither actin assembly nor characteristic P2X7R channel activity was seen in response to ATP in P2X7R-knockout macrophages, as detected by patch-clamp analysis. Since P2X7R has been shown previously to form a macromolecular complex with actin we propose that it is involved in the membrane assembly of actin. Our data reveal a surprisingly rapid and complex relay of signaling and externalization events that precede and control actin assembly induced by sphingosine-1-phosphate. The overall model we present is strongly supported by the data presented in the accompanying paper that focuses on latex bead phagosomes.
Kuehnel
Mark P
MP
EMBL, Meyerhofstr. 1, 69117 Heidelberg, Germany.
Reiss
Miriam
M
Anand
Paras K
PK
Treede
Irina
I
Holzer
Daniela
D
Hoffmann
Eik
E
Klapperstueck
Manuela
M
Steinberg
Thomas H
TH
Markwardt
Fritz
F
Griffiths
Gareth
G
D000199:Actins / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000263:Adenylate Kinase / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D018929:Cell Culture Techniques; D002462:Cell Membrane / Q000378:metabolism; D008246:Lysophospholipids / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D049349:Receptors, Lysosphingolipid / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000172:deficiency / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism
D000199:Actins; D008246:Lysophospholipids; C546469:P2rx7 protein, mouse; D049349:Receptors, Lysosphingolipid; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; C060506:sphingosine 1-phosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000263:Adenylate Kinase; D013110:Sphingosine