title: Responses of macrophages to the danger signals released from necrotic cells.
abstract: The immune system maintains homeostasis by recognizing and responding to cell death caused by various stresses. The immune response is considered to be elicited by 'danger signals' released from necrotic cells. However, the identity of the danger signals remains elusive. In this study, we focused on the expression of chemokines by macrophages stimulated with necrotic cells. In mouse bone-marrow-derived macrophages, the chemokine monocyte chemoattractant protein (MCP)-3 was induced at both the mRNA and protein levels in response to heat-killed murine cells. The induction of MCP-3 was also observed in MyD88-deficient macrophages, indicating that Toll-like receptors and the IL-1 receptor are not involved in this response. Consistent with this observation, the activation of NF-κB was not detected in RAW264.7 macrophages stimulated with necrotic cells. Treatments with proteinase K, DNaseI or RNaseA did not affect the ' STIMULATING ACTIVITY': of necrotic cells. In contrast, treatment with apyrase, which removes phosphates from nucleoside tri- and di-phosphates, abolished the inducing activity. Purified UDP at 30 µM concentration elicited similar induction of MCP-3 in RAW264.7 macrophages. Small interfering RNA-mediated knock-down of the UDP receptor P2Y6 in RAW264.7 cells significantly reduced the induction of MCP-3 in response to necrotic cells, but not its induction by lipopolysaccharide. Furthermore, ectopic expression of the P2Y6 receptor in HEK293 cells conferred responsiveness to necrotic cells. These results suggest that UDP released by necrotic cells plays a critical role as an endogenous danger signal and that P2Y6 is required for the induction of MCP-3 in response to necrotic cells.
authors.affiliation: Laboratory of Cell Recognition and Response, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Laboratory of Cell Recognition and Response, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Laboratory of Cell Recognition and Response, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
authors.forename: Fumito
authors.initials: F
authors.lastname: Hanihara-Tatsuzawa
authors.affiliation: Laboratory of Cell Recognition and Response, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
authors.forename: Aoi
authors.initials: A
authors.lastname: Sayama
authors.affiliation: Laboratory of Cell Recognition and Response, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan Laboratory of Cell Signaling, School of Medicine, Gifu University, Gifu 501-1194, Japan ta-maru@umin.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: MaruYama
authors.affiliation: Laboratory of Cell Recognition and Response, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Muta
mesh_terms: D000818:Animals; D002460:Cell Line; D054410:Chemokine CCL7 / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D017472:Receptors, Interleukin-1 / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D015398:Signal Transduction; D051193:Toll-Like Receptors / Q000378:metabolism; D014530:Uridine Diphosphate / Q000494:pharmacology
chemical_list: D054410:Chemokine CCL7; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D017472:Receptors, Interleukin-1; D018048:Receptors, Purinergic P2; D051193:Toll-Like Receptors; C099845:purinoceptor P2Y6; D014530:Uridine Diphosphate
keywords: P2Y6; chemokine; danger signal; inflammation; necrosis