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。CD38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。本研究探讨了cADPR对Ca^<2+>动态的调控及其在人中性粒细胞中的生理作用。cADPR诱导地黄素渗透中性粒细胞释放Ca^<2+>，并被cADPR、FK506和雷帕霉素的拮抗剂8Br-cADPR阻断。fMLP和PAF诱导[Ca^<2+>]i开始快速升高，随后完整中性粒细胞持续升高。在培养基中加入β-NAD^+使[Ca^<2+>]i增加。8Br-cADPR、抗cd38抗体、FK506、雷帕霉素、NAD…More酶和几种核苷转运体（NT）抑制剂可降低趋化吸引素-和β-NAD^+-诱导的[Ca^<2+>]i升高。ENT_1、ENT_2、CNT_2、CNT_3在中性粒细胞中表达。这些结果表明，CD38在细胞外合成的cADPR通过nt转运到细胞内，并通过fk506结合蛋白依赖过程动员Ca^<2+>，是Ca^<2+>持续内流中性粒细胞所必需的。EGTA或8Br-cADPR预处理人中性粒细胞特异性阻断fMLP或PAF刺激的趋化作用。同样，用FK506、抗cd38抗体、NADase和NT抑制剂处理中性粒细胞可阻断对fMLP或PAF的趋化性。这些结果表明，中性粒细胞对fMLP和PAF的趋化性依赖于cADPR介导的Ca^<2+>的动员。因此，cADPR通过其产生cADPR来控制中性粒细胞对趋化剂的趋化性，并作为炎症和先天免疫反应的关键调节剂。由于许多受cADPR调控的趋化受体与临床病理相关的配体结合，cADPR、CD38和nt代表了新的药物靶点，在慢性炎症和神经退行性疾病中具有潜在的应用前景。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