title: Real-time imaging reveals that P2Y2 and P2Y12 receptor agonists are not chemoattractants and macrophage chemotaxis to complement C5a is phosphatidylinositol 3-kinase (PI3K)- and p38 mitogen-activated protein kinase (MAPK)-independent.
abstract: Adenosine 5'-triphosphate (ATP) has been implicated in the recruitment of professional phagocytes (neutrophils and macrophages) to sites of infection and tissue injury in two distinct ways. First, ATP itself is thought to be a chemotactic "find me" signal released by dying cells, and second, autocrine ATP signaling is implicated as an amplifier mechanism for chemotactic navigation to end-target chemoattractants, such as complement C5a. Here we show using real-time chemotaxis assays that mouse peritoneal macrophages do not directionally migrate to stable analogs of ATP (adenosine-5'-(γ-thio)-triphosphate (ATPγS)) or its hydrolysis product ADP (adenosine-5'-(β-thio)-diphosphate (ADPβS)). HPLC revealed that these synthetic P2Y(2) (ATPγS) and P2Y(12) (ADPβS) receptor ligands were in fact slowly degraded. We also found that ATPγS, but not ADPβS, promoted chemokinesis (increased random migration). Furthermore, we found that photorelease of ATP or ADP induced lamellipodial membrane extensions. At the cell signaling level, C5a, but not ATPγS, activated Akt, whereas both ligands induced p38 MAPK activation. p38 MAPK and Akt activation are strongly implicated in neutrophil chemotaxis. However, we found that inhibitors of phosphatidylinositol 3-kinase (PI3K; upstream of Akt) and p38 MAPK (or conditional deletion of p38α MAPK) did not impair macrophage chemotactic efficiency or migration velocity. Our results suggest that PI3K and p38 MAPK are redundant for macrophage chemotaxis and that purinergic P2Y(2) and P2Y(12) receptor ligands are not chemotactic. We propose that ATP signaling is strictly autocrine or paracrine and that ATP and ADP may act as short-range "touch me" (rather than long-range find me) signals to promote phagocytic clearance via cell spreading.
authors: Institut für Physiologie II, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors: Katrin
authors: K
authors: Isfort
authors: Franziska
authors: F
authors: Ebert
authors: Julia
authors: J
authors: Bornhorst
authors: Sarah
authors: S
authors: Sargin
authors: Rozina
authors: R
authors: Kardakaris
authors: Manolis
authors: M
authors: Pasparakis
authors: Martin
authors: M
authors: Bähler
authors: Tanja
authors: T
authors: Schwerdtle
authors: Albrecht
authors: A
authors: Schwab
authors: Peter J
authors: PJ
authors: Hanley
mesh_terms: D000244:Adenosine Diphosphate / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D019898:Autocrine Communication / Q000187:drug effects / Q000502:physiology; D002633:Chemotaxis / Q000187:drug effects / Q000502:physiology*; D015936:Complement C5a / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019899:Paracrine Communication / Q000187:drug effects / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011554:Pseudopodia / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D058912:Purinergic P2Y Receptor Agonists / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D058925:Receptors, Purinergic P2Y12 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D058473:Receptors, Purinergic P2Y2 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: C548577:P2ry12 protein, mouse; D058912:Purinergic P2Y Receptor Agonists; D058925:Receptors, Purinergic P2Y12; D058473:Receptors, Purinergic P2Y2; D000244:Adenosine Diphosphate; D015936:Complement C5a; D000255:Adenosine Triphosphate; D019869:Phosphatidylinositol 3-Kinases; D048051:p38 Mitogen-Activated Protein Kinases