Evidence of a role for cyclic ADP-ribose in calcium signaling and migration in human neutrophils

环ADP核糖（cADPR）具有强大的Ca^2+动员作用，并作为许多激动剂的第二信使，从而调节大量Ca^2+介导的细胞过程。CD 38是最具特征的哺乳动物ADP-核糖基环化酶，被认为是体内cADPR的重要来源。虽然[Ca^<2+>]i的增加是中性粒细胞功能的关键信号，但[Ca^<2+>]i的调节机制尚不清楚。cADPR可诱导毛地黄皂苷透化的中性粒细胞释放Ca ^2+，cADPR拮抗剂8 Br-cADPR、FK 506和雷帕霉素可阻断cADPR的释放。fMLP和PAF诱导完整中性粒细胞[Ca^2+]i的初始快速升高和随后的持续升高。加入β-NAD^+可增加[Ca^<2+>]i。8 Br-cADPR、抗CD 38抗体、FK 506、雷帕霉素、NAD^+可降低趋化因子和β-NAD^+诱导的[Ca^<2+]i升高 关于我们 酶和几种核苷转运蛋白（NT）抑制剂。ENT_1、ENT_2、CNT_2、CNT_3在中性粒细胞中表达。这些结果表明，cADPR由CD 38合成，并通过NT转运到细胞内，通过FK 506结合蛋白依赖的过程动员Ca^2+，是中性粒细胞持续Ca^2+内流所必需的，EGTA或8Br-cADPR预处理人中性粒细胞可特异性阻断fMLP或PAF刺激的趋化反应。同样地，用FK 506、抗CD 38抗体、NADase和NT抑制剂处理中性粒细胞阻断了对fMLP或PAF的趋化性。这些结果表明，中性粒细胞对fMLP和PAF的趋化依赖于cADPR介导的Ca^2+动员，因此cADPR通过产生cADPR控制中性粒细胞对趋化因子的趋化，并在炎症反应和先天免疫反应中起重要调节作用。由于许多由cADPR调节的化学引诱物受体与临床病理学相关的配体结合，cADPR、CD 38和NT代表了在慢性炎症和神经退行性疾病中具有潜在应用的新型药物靶点。少

Cyclic ADP-ribose (cADPR) has a powerful Ca^<2+>-mobilizing action and behaves as a second messenger of many agonists, thereby modulating a wide number of Ca^<2+>-mediated cell processes. CD38, the best-characterized mammalian ADP-ribosyl cyclase, is postulated to be an important source of cADPR in vivo. Although an increase in [Ca^<2+>]i is a key signal neutrophil functions, the mechanisms for regulation of [Ca^<2+>]i is unclear. The present study examined the regulation by cADPR of Ca^<2+> dynamics and its physiological role in human neutrophils.cADPR induced Ca^<2+> release from digitonin-permeabilized neutrophils and the release was blocked by 8Br-cADPR, an antagonist of cADPR and FK506 and rapamycin. fMLP and PAF induced a initial rapid rise of [Ca^<2+>]i and the following sustained rise in intact neutrophils. β-NAD^+ added into the medium increased [Ca^<2+>]i. Chemoattractans- and β-NAD^+-induced [Ca^<2+>]i rise were reduced by 8Br-cADPR, anti-CD38 antibody, FK506, rapamycin, NAD … More ase and several nucleoside transporter (NT) inhibitors. ENT_1, ENT_2, CNT_2, CNT_3 are expressed in neutrophils. These results suggest that cADPR synthesized extracellulary by CD38 transported into the cells through NTs and mobilize Ca^<2+> by FK506-binding protein-dependent process and is required for sustained Ca^<2+> influx in neutrophils.Pretreatment of human neutrophils with either EGTA or 8Br-cADPR specifically blocked the chemotsxis stimulated with fMLP or PAF. Likewise, treatment of neutrophils with FK506, anti-CD38 antibody, NADase and NT inhibitors blocked the chemotaxis to fMLP or PAF. These results demonstrate that neutrophil chemotaxis to fMLP and PAF are dependent on Ca^<2+> mobilization mediated by cADPR.Thus, cADPR controls neutrophil chemotaxis to chemoattractants through its production of cADPR, and acts as a critical regulator of inflammation and innate immune responses. Since many of the chemoattractant receptors regulated by cADPR bind to ligands that are associated with clinical pathology, cADPR, CD38 and NTs represent novel drug targets with potential application in chronic inflammatory and neurodegenerative disease. Less