Lysine 129 of CD38 (ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase) participates in the binding of ATP to inhibit the cyclic ADP-ribose hydrolase

CD38 catalyzes not only the formation of cyclic ADP-ribose (cADPR) from NAD+ but also the hydrolysis of cADPR to ADP-ribose (ADPR), and ATP inhibits the hydrolysis (Takasawa, S., Tohgo, A., Noguchi, N., Koguma, T., Nata, K., Sugimoto, T., Yonekura, H., and Okamoto, H. (1993) J. Biol. Chem. 268, 26052-26054). In the present study, using purified recombinant CD38, we showed that the cADPR hydrolase activity of CD38 was inhibited by ATP in a competitive manner with cADPR. To identify the binding site for ATP and/or cADPR, we labeled the purified CD38 with FSBA. Sequence analysis of the lysylendopeptidase-digested fragment of the labeled CD38 indicated that the FSBA-labeled residue was Lys-129. We introduced site-directed mutations to change the Lys-129 of CD38 to Ala and to Arg. Neither mutant was labeled with FSBA nor catalyzed the hydrolysis of cADPR to ADPR. Furthermore, the mutants did not bind cADPR, whereas they still used NAD+ as a substrate to form cADPR and ADPR. These results indicate that Lys-129 of CD38 participates in cADPR binding and that ATP competes with cADPR for the binding site, resulting in the inhibition of the cADPR hydrolase activity of CD38.     

CD38 and ADP-ribosyl cyclase catalyze the synthesis of a dimeric ADP-ribose that potentiates the calcium-mobilizing activity of cyclic ADP-ribose

CD38, a lymphocyte differentiation antigen, is also a bifunctional enzyme catalyzing the synthesis of cyclic ADP-ribose (cADPR) from NAD+ and its hydrolysis to ADP-ribose (ADPR). An additional enzymatic activity of CD38 shared by monofunctional ADP-ribosyl cyclase from Aplysia californica is the exchange of the base group of NAD+ (nicotinamide) with various nucleophiles. Both human CD38 (either recombinant or purified from erythrocyte membranes) and Aplysia cyclase were found to catalyze the exchange of ADPR with the nicotinamide group of NAD+ leading to the formation of a dimeric ADPR ((ADPR)2). The dimeric structure of the enzymatic product, which was generated by recombinant CD38 and by CD38(+) Namalwa cells from as low as 10 microM NAD+, was demonstrated using specific enzyme treatments (dinucleotide pyrophosphatase and 5'-nucleotidase) and mass spectrometry analyses of the resulting products. The linkage between the two ADPR units of (ADPR)2 was identified as that between the N1 of the adenine nucleus of one ADPR unit and the anomeric carbon of the terminal ribose of the second ADPR molecule by enzymatic analyses and by comparison with patterns of cADPR cleavage with Me2SO:tert-butoxide. Although (ADPR)2 itself did not release Ca2+ from sea urchin egg microsomal vesicles, it specifically potentiated the Ca2+-releasing activity of subthreshold concentrations of cADPR. Therefore, (ADPR)2 is a new product of CD38 that amplifies the Ca2+-mobilizing activity of cADPR.     

The transmembrane glycoprotein CD38 is a catalytically active transporter responsible for generation and influx of the second messenger cyclic ADP-ribose across membranes

CD38 is a type II transmembrane glycoprotein expressed in many vertebrate cells. It is a bifunctional ectoenzyme that catalyzes both the synthesis of Cyclic ADP-ribose (cADPR) from NAD+ and the degradation of cADPR to ADP-ribose by means of its ADP-ribosyl cyclase and cADPR-hydrolase activities, respectively. The cyclase also converts NGD+ to cyclic GDP-ribose (cGDPR), which is refractory to cADPR-hydrolase. cADPR, but not cGDPR, is a potent calcium mobilizer from intracellular stores. It has been demonstrated to be a new second messenger involved in the regulation of calcium homeostasis in many cell types, from plants to mammals. The number of physiological processes shown to be regulated by cADPR is steadily increasing. A topological paradox exists because ectocellularly generated cADPR acts intracellularly. Here we demonstrate that the catalytic functioning of CD38 is accompanied by a cADPR (cGDPR) -transporting activity across natural and artificial membranes. In resealed membranes from CD38(+) human erythrocytes, transport of catalytically generated cADPR or cGDPR was saturation dependent and occurred against a concentration gradient. Likewise, CD38-reconstituted proteoliposomes were active in concentrating NAD+ (NGD+) -derived cADPR (cGDPR) inside the vesicle compartment. Moreover, the cADPR-transporting activity in CD38 proteoliposomes prevented the hydrolase-catalyzed degradation to ADPR that occurs conversely with detergent-solubilized CD38, resulting in selective influx of cADPR. In the CD38 proteoliposomes, catalytically active CD38 exhibited monomeric, dimeric, and tetrameric structures. In CD38 sense- but not in antisense-transfected HeLa cells, externally added NAD+ resulted in significant, transient increases in cytosolic calcium. These data suggest that transmembrane juxtaposition of two or four CD38 monomers can generate a catalytically active channel for selective formation and influx of cADPR (cGDPR) to reach cADPR-responsive intracellular calcium stores.     

Autoantibodies against CD38 (ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase) that impair glucose-induced insulin secretion in noninsulin- dependent diabetes patients

Cyclic ADP-ribose (cADPR) has been shown to be a mediator for intracellular Ca2+ mobilization for insulin secretion by glucose in pancreatic beta cells, and CD38 shows both ADP-ribosyl cyclase to synthesize cADPR from NAD+ and cADPR hydrolase to hydrolyze cADPR to ADP-ribose. We show here that 13.8% of Japanese non-insulin-dependent diabetes (NIDDM) patients examined have autoantibodies against CD38 and that the sera containing anti-CD38 autoantibodies inhibit the ADP-ribosyl cyclase activity of CD38 (P 相似文献   

CD38 disruption impairs glucose-induced increases in cyclic ADP-ribose, [Ca2+]i, and insulin secretion

Increases in [Ca2+]i in pancreatic beta cells, resulting from Ca2+ mobilization from intracellular stores as well as Ca2+ influx from extracellular sources, are important in insulin secretion by glucose. Cyclic ADP-ribose (cADPR), accumulated in beta cells by glucose stimulation, has been postulated to serve as a second messenger for intracellular Ca2+ mobilization for insulin secretion, and CD38 is thought to be involved in the cADPR accumulation (Takasawa, S., Tohgo, A., Noguchi, N., Koguma, T., Nata, K., Sugimoto, T., Yonekura, H., and Okamoto, H. (1993) J. Biol. Chem. 268, 26052-26054). Here we created "knockout" (CD38(-/-)) mice by homologous recombination. CD38(-/-) mice developed normally but showed no increase in their glucose-induced production of cADPR in pancreatic islets. The glucose-induced [Ca2+]i rise and insulin secretion were both severely impaired in CD38(-/-) islets, whereas CD38(-/-) islets responded normally to the extracellular Ca2+ influx stimulants tolbutamide and KCl. CD38(-/-) mice showed impaired glucose tolerance, and the serum insulin level was lower than control, and these impaired phenotypes were rescued by beta cell-specific expression of CD38 cDNA. These results indicate that CD38 plays an essential role in intracellular Ca2+ mobilization by cADPR for insulin secretion.     

The functional paradox of CD43 in leukocyte recruitment: a study using CD43-deficient mice

OBJECTIVE: To determine the variable most closely related to symptomatic relief of osteoarthritis (OA) of the knee in response to a weight control program. METHODS: Twenty-two patients diagnosed with knee OA whose body mass index (BMI) was more than 26.4 were treated with a low calorie diet, an appetite suppressant, and nonsteroidal antiinflammatory drugs for 6 weeks. The patients were instructed to follow a walking program. We analyzed BMI, percent body fat, the average number of steps per day by pedometer, and the metabolic correlates of obesity (blood pressure, fasting blood serum glucose, total cholesterol, triglycerides, and serum insulin) at the beginning and end of therapy. The correlation between the change in each variable and the remission score (delta score) using the Severity Index of Lequesne, et al was evaluated. RESULTS: Delta score of knee OA was more strongly associated with reduction in percent body fat (p= 0.0013, r=0.62) than other variables. Significant correlation was also observed between the number of steps per day and delta score (p=0.0031, r=-0.58). No other variable, including weight loss, was significantly correlated with delta score. There was a significant correlation between delta percent body fat and the number of steps per day (p=0.012, r=-0.62). CONCLUSION: In a weight control program, decreasing body fat and increasing physical activity are more important than body weight loss or decreasing other indices of obesity in producing symptomatic relief of knee OA, although there is not necessarily a cause and effect relationship between body fat and OA score.     

A topological approach to nucleosome structure and dynamics: the linking number paradox and other issues

The linking number paradox of DNA in chromatin (two negative crossings around the octamer, associated with a unit linking number reduction), which is 21 years old this year, has come of age. After stirring much debate in the past, the initially hypothetical explanation of the paradox by DNA overtwisting on the nucleosome surface is now presented as a hard fact in recent textbooks. The first part of this article presents a historical perspective of the problem and details the numerous attempts to measure DNA local periodicity, which in one remarkable example sowed the seeds for the discovery of DNA bending. The second part is devoted to the DNA minicircle system, which has been developed in the author's laboratory as an alternative to the local-periodicity-measurement approach. It offers a simple proposal: a unit linking number reduction associated with a single crossing. This conclusion is contrasted with the latest high-resolution crystallographic data of the nucleosome in the third part of the article, and the fourth part examines the available evidence supporting an extension of these results to nucleosomes in chromatin. The last part addresses another basic question pertaining to nucleosome dynamics, the conformational flexibility of the histone tetramer.     

CD2 rescues T cells from T-cell receptor/CD3 apoptosis: a role for the Fas/Fas-L system

Anti-CD3 monoclonal antibodies (MoAbs) and glucocorticoid hormones induce apoptosis in immature thymocytes and peripheral T lymphocytes. This process is inhibited by a number of growth factors, including interleukin-2 (IL-2), IL-3, and IL-4, as well as by triggering of the adhesion molecule CD44, which would indicate that signals generated by membrane receptors can modulate the survival of lymphoid cells. To investigate whether triggering of CD2 may also affect apoptosis in lymphoid cells, we analyzed the effect of stimulation with anti-CD2 MoAbs on T-cell apoptosis induced by two stimuli, anti-CD3 MoAbs and dexamethasone (DEX), using a hybridoma T-cell line and a T-helper cell clone. The results show that CD2 engagement decreased anti-CD3 MoAb-induced apoptosis, but did not influence DEX-induced cell death. Furthermore, the decrease appeared to be related to the expression of Fas/APO-1 (CD95) and Fas-ligand (Fas-L). In fact, we show that CD2 stimulation inhibits apoptosis by preventing the CD3-induced upregulation of Fas and Fas-L in a Fas-dependent experimental system. These data suggest that a costimulatory molecule may control a deletion pathway and may therefore contribute to the regulation of peripheral tolerance.     

CD38 is functionally dependent on the TCR/CD3 complex in human T cells

One of the functions of surface CD38 is the induction of phosphorylation of discrete cytoplasmic substrates and mobilization of cytoplasmic calcium (Ca2+). The present work addresses the issue of whether the signaling mediated via CD38 operates through an independent pathway or, alternatively, is linked to the TCR/CD3 signaling machinery. We studied the signals elicited through CD38 by the specific agonistic IB4 monoclonal antibody (mAb) by monitoring the levels of cytoplasmic Ca2+ and the induced phenotypic and functional variations in T cell growth. IB4 mAb presented the unique ability to increase cytoplasmic Ca2+ levels, which correlated with the phosphorylation of the PLC-gamma1. These effects were blocked by phorbol 12-myristate 13-acetate (PMA) and were dependent on the presence of a functional TCR/CD3 surface complex, no effects being recorded on mutant Jurkat cells lacking part of the CD3 structures. CD38 signaling appeared to share with TCR/CD3 the ability to induce apoptotic cell death in Jurkat T cells, an event paralleled by specific up-regulation of the Fas molecule and inhibited by cyclosporin A. CD28, a costimulatory molecule, is synergized by increasing CD38-induced apoptotic cell death. The results indicate the existence of a strong functional interdependence between CD38 and TCR/CD3.     

Poly (ADP-ribose) polymerase, a potential target for drugs: Part II. Regulation of differentiation by the poly ADP-ribose system

It is shown that eukaryotic differentiation is specifically sensitive to pADPRT regulation in Trypanosomna, Leishmania and Mytilus models. There is powerful inhibition of early differentiation without cell toxicity by pADPRT ligands.     

Liver transplantation: the death/life paradox

Chronic encapsulated intracerebral hematoma (CEIH) is a rare disease which is believed to be caused by angiographically negative vascular malformations. CEIH has the following characteristic findings: 1. It affects all age groups 2. Clinical symptoms progress slowly after sudden onset. Often there is a latency of months or years 3. There is no correlation with arterial hypertension 4. Imaging reveals a typical fibrous capsule with enclosed blood contents and signs of recurrent bleedings 5. Cavernoma was identified histologically as the cause of bleeding in 30% of cases. 6. All patients had a primary diagnosis of intracerebral tumor. To the best of our knowledge, 27 cases have been reported in the literature. We now add two cases, one of which is the first in the available literature which was not operated and could be followed by imaging.     

The paradox of HIV/AIDS as expanding consciousness

A heuristic approach employing Newman's method for pattern identification was used to examine the theory of health as expanding consciousness in persons with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). Themes derived from the interview of nine gay men portrayed a pattern of alienation during childhood, followed by a breaking away from family, and progressing to cycles of aloneness and searching. Recognition of HIV/AIDS in their lives brought them to a turning point of more meaningful connectedness. This pattern is viewed as expanding consciousness and possibly a phenomenon of cultural evolution.     

Differential oligomerization of membrane-bound CD38/ADP-ribosyl cyclase in porcine heart microsomes

A protein fraction displaying ADP-ribosyl cyclase activity was purified from porcine heart microsomes which appeared as a major band of 45 kDa on Coomassie blue stained SDS-PAGE gel under reducing condition. Protein immunoblot analysis with antiserum to recombinant rat CD38 showed a series of bands (45-285 kDa) under nonreducing condition, while only the 45 kDa monomer under reducing condition. The high molecular weight oligomers of CD38 were found to be stable even upon treatment with various concentrations of SDS in the sample buffer and also upon incubation at lower temperature. These oligomers of CD38 also displayed higher ADP-ribosyl cyclase activity than that of the monomer.     

Lipids and stroke: a paradox resolved

The usual methods like hypotension, isovolaemic haemodilution, autologous transfusion and peri-operative blood salvage may significantly reduce the need for homologous blood transfusion in haemorrhagic surgery and also the risk of transmitting infectious agents. Erythropoietin (EPO) is now available and is used to stimulate red cell regeneration in pre-operative autologous blood donation. In acute anaemia, many studies have shown that the stimulation of endogenous erythropoietin production could be very high and accelerate red blood cell production. Taking higher quantities of blood than usual induces a secretion of endogenous erythropoietin, and could be an alternative for the utilization of exogenous EPO in autologous blood donation.     

Review of Building bridges: The negotiation of paradox in psychoanalysis.

Review of book: Stuart A. Pizer (Au.) Building bridges: The negotiation of paradox in psychoanalysis. Hillsdale, NJ: Analytic Press, 1998, xix + 220 pp.. Reviewed by Leon S. Anisfeld. (PsycINFO Database Record (c) 2010 APA, all rights reserved)