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Ramesh S, Almeida SD, Hammigi S, Radhakrishna GK, Sireesha G, Panneerselvam T, Vellingiri S, Kunjiappan S, Ammunje DN, Pavadai P. A Review of PARP-1 Inhibitors: Assessing Emerging Prospects and Tailoring Therapeutic Strategies. Drug Res (Stuttg) 2023; 73:491-505. [PMID: 37890514 DOI: 10.1055/a-2181-0813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2023]
Abstract
Eukaryotic organisms contain an enzyme family called poly (ADP-ribose) polymerases (PARPs), which is responsible for the poly (ADP-ribosylation) of DNA-binding proteins. PARPs are members of the cell signaling enzyme class. PARP-1, the most common isoform of the PARP family, is responsible for more than 90% of the tasks carried out by the PARP family as a whole. A superfamily consisting of 18 PARPs has been found. In order to synthesize polymers of ADP-ribose (PAR) and nicotinamide, the DNA damage nick monitor PARP-1 requires NAD+ as a substrate. The capability of PARP-1 activation to boost the transcription of proinflammatory genes, its ability to deplete cellular energy pools, which leads to cell malfunction and necrosis, and its involvement as a component in the process of DNA repair are the three consequences of PARP-1 activation that are of particular significance in the process of developing new drugs. As a result, the pharmacological reduction of PARP-1 may result in an increase in the cytotoxicity toward cancer cells.
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Affiliation(s)
- Soundarya Ramesh
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, M.S. Ramaiah University of Applied Sciences, M S R Nagar, Bengaluru, India
| | - Shannon D Almeida
- Department of Pharmacology, Faculty of Pharmacy, M.S. Ramaiah University of Applied Sciences, M S R Nagar, Bengaluru, India
| | - Sameerana Hammigi
- Department of Pharmacology, Faculty of Pharmacy, M.S. Ramaiah University of Applied Sciences, M S R Nagar, Bengaluru, India
| | - Govardan Katta Radhakrishna
- Department of Pharmacology, Faculty of Pharmacy, M.S. Ramaiah University of Applied Sciences, M S R Nagar, Bengaluru, India
| | - Golla Sireesha
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, M.S. Ramaiah University of Applied Sciences, M S R Nagar, Bengaluru, India
| | - Theivendren Panneerselvam
- Department of Pharmaceutical Chemistry, Swamy Vivekanandha College of Pharmacy, Elayampalayam, Tamil Nadu, India
| | - Shangavi Vellingiri
- Department of Pharmacy Practice, Swamy Vivekananda College of Pharmacy, Elayampalayam, Tamil Nadu, India
| | - Selvaraj Kunjiappan
- Department of Biotechnology, Kalasalingam Academy of Research and Education, Krishnankoil, Tamil Nadu, India
| | - Damodar Nayak Ammunje
- Department of Pharmacology, Faculty of Pharmacy, M.S. Ramaiah University of Applied Sciences, M S R Nagar, Bengaluru, India
| | - Parasuraman Pavadai
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, M.S. Ramaiah University of Applied Sciences, M S R Nagar, Bengaluru, India
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Sheline CT, Shi C, Takata T, Zhu J, Zhang W, Sheline PJ, Cai AL, Li L. Dietary zinc reduction, pyruvate supplementation, or zinc transporter 5 knockout attenuates β-cell death in nonobese diabetic mice, islets, and insulinoma cells. J Nutr 2012; 142:2119-27. [PMID: 23096014 PMCID: PMC3497962 DOI: 10.3945/jn.112.167031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Pancreatic zinc (Zn(2+)) concentrations are linked to diabetes and pancreatic dysfunction, but Zn(2+) is also required for insulin processing and packaging. Zn(2+) released with insulin increases β-cell pancreatic death after streptozotocin toxin exposure in vitro and in vivo. Triosephosphate accumulation, caused by NAD(+) loss and glycolytic enzyme dysfunction, occur in type-1 diabetics (T1DM) and animal models. We previously showed these mechanisms are also involved in Zn(2+) neurotoxicity and are attenuated by nicotinamide- or pyruvate-induced restoration of NAD(+) concentrations, Zn(2+) restriction, or inhibition of Sir2 proteins. We tested the hypothesis that similar Zn(2+)- and NAD(+)-mediated mechanisms are involved in β-cell toxicity in models of ongoing T1DM using mouse insulinoma cells, islets, and nonobese diabetic (NOD) mice. Zn(2+), streptozotocin, and cytokines caused NAD(+) loss and death in insulinoma cells and islets, which were attenuated by Zn(2+) restriction, pyruvate, nicotinamide, NAD(+), and inhibitors of Sir2 proteins. We measured diabetes incidence and mortality in NOD mice and demonstrated that pyruvate supplementation, or genetic or dietary Zn(2+) reduction, attenuated these measures. T-lymphocyte infiltration, punctate Zn(2+) staining, and β-cell loss increased with time in islets of NOD mice. Dietary Zn(2+) restriction or Zn(2+) transporter 5 knockout reduced pancreatic Zn(2+) staining and increased β-cell mass, glucose homeostasis, and survival in NOD mice, whereas Zn(2+) supplementation had the opposite effects. Pancreatic Zn(2+) reduction or NAD(+) restoration (pyruvate or nicotinamide supplementation) are suggested as novel targets for attenuating T1DM.
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Affiliation(s)
- Christian T. Sheline
- Department of Ophthalmology and the Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA,To whom correspondence should be addressed. E-mail:
| | | | - Toshihiro Takata
- Department of Internal and Geriatric Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Julia Zhu
- University of Cincinnati Medical Program, Cincinnati, OH
| | - Wenlan Zhang
- Duke University Medical Program, Durham, NC; and
| | | | - Ai-Li Cai
- Department of Biomedical Engineering, Washington University, Saint Louis, MO
| | - Li Li
- Department of Ophthalmology and the Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA
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Polymeric delivery of therapeutic RAE-1 plasmid to the pancreatic islets for the prevention of type 1 diabetes. J Control Release 2012; 162:606-11. [PMID: 22910142 DOI: 10.1016/j.jconrel.2012.08.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/01/2012] [Accepted: 08/06/2012] [Indexed: 12/31/2022]
Abstract
The activating receptor NKG2D plays an important role in the development of type-1 diabetes. Exploiting a natural phenomenon observed in tumors, plasmid DNA encoding for a soluble ligand to NKG2D (sRAE-1γ) was isolated and engineered into a plasmid expression system. A polymeric gene delivery system was developed to deliver the soluble RAE-1 plasmid to the pancreatic islets. The bioreducible cationic polymer poly(cystamine bisacrylamide-diamino hexane) (p(CBA-DAH)) was modified with poly(ethylene glycol) (PEG) and the targeting peptide CHVLWSTRC, known to target the EphA2 and EphA4 receptors. We observed a higher uptake of the targeting polymer Eph-PEG-p(CBA-DAH) in the pancreas of NOD mice compared to non-targeting controls. To evaluate the efficacy of preventing diabetes, the Eph-PEG-p(CBA-DAH)/RAE-1 complex (polyplex) was intravenously injected into 6-week-old female NOD mice. Within 17 weeks blood glucose levels were stabilized in animals injected with polyplex, while those treated without therapeutic plasmid developed progressive hyperglycemia. Additionally, the degree of insulitis and the infiltration of CD8⁺ T-cells in the polyplex treated group were improved over the targeting polymer only treated group. The current study suggests that the therapy of the Eph-PEG-p (CBA-DAH) delivering therapeutic sRAE-1 gene may be used to protect β-cells from autoimmune destruction and prevent type-1 diabetes.
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Sheline CT. Involvement of SIRT1 in Zn 2+, Streptozotocin, Non-Obese Diabetic, and Cytokine-Mediated Toxicities of β-cells. JOURNAL OF DIABETES & METABOLISM 2012; 3:1000193. [PMID: 23565341 PMCID: PMC3615451 DOI: 10.4172/2155-6156.1000193] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Zn2+ toxicity is implicated in pancreatic β-cell death that occurs secondarily to: streptozotocin exposure in vitro; and both autoimmune attack or streptozotocin in vivo models of T1DM. This is demonstrated by reduced β-cell death or diabetic incidence in vitro or in NOD mice after treatment with Zn2+ preferring chelators, pyruvate, nicotinamide, a reduced zinc diet, sirtuin inhibitors, or zinc transporter knockout. These therapeutics are also demonstrated to be efficacious against Zn2+ neurotoxicity. AIMS To determine if the sirtuin pathway is involved in Zn2+-, streptozotocin-, or cytokine-mediated β-cell death in vitro, and streptozotocin-, or NOD induced T1DM in vivo. METHODS Sensitivity of MIN6 cells expressing empty vector, sirtuin protein-1 (SIRT1) or its siRNA, to Zn2+, streptozotocin, or cytokines, and effects on NAD+ levels were determined. Covariance of manipulating SIRT1 levels with diabetic incidence was tested in vivo. RESULTS 1) sirtuin pathway inhibition or SIRT1 knockdown attenuated Zn2+-, STZ-, and cytokine-mediated toxicity and NAD+ loss in β-cells, 2) SIRT1 overexpression potentiated these toxicities, 3) young SIRT1 β-cell transgenic mice have improved glucose tolerance under basal conditions, but upon aging showed increased sensitivity to streptozotocin compared to SIRT1 +/- mice, and 4) SIRT1 +/- mice in an NOD background or exposed to streptozotocin trended toward reduced diabetic incidence and mortality compared to wildtype. CONCLUSIONS These results have implicated SIRT1-mediated NAD+ loss in Zn2+, STZ, or cytokine toxicities of MIN6, and in NOD or streptozotocin T1DM animal models. Modulation of β-cell Zn2+ and NAD+ levels, and the sirtuin pathway could be novel therapeutic targets for T1DM.
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Zhu SS, Ren Y, Zhang M, Cao JQ, Yang Q, Li XY, Bai H, Jiang L, Jiang Q, He ZG, Chen Q. Wld(S) protects against peripheral neuropathy and retinopathy in an experimental model of diabetes in mice. Diabetologia 2011; 54:2440-50. [PMID: 21739347 DOI: 10.1007/s00125-011-2226-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Accepted: 05/31/2011] [Indexed: 10/18/2022]
Abstract
AIMS/HYPOTHESIS We aimed to evaluate the effect of the mutant Wld(S) (slow Wallerian degeneration; also known as Wld) gene in experimental diabetes on early experimental peripheral diabetic neuropathy and diabetic retinopathy. METHODS The experiments were performed in four groups of mice: wild-type (WT), streptozotocin (STZ)-induced diabetic WT, C57BL/Wld(S) and STZ-induced diabetic C57BL/Wld(S). In each group, intraperitoneal glucose and insulin tolerance tests were performed; blood glucose, glycated haemoglobin and serum insulin were monitored. These mice were also subjected to the following behavioural tests: grasping test, hot-plate test and von Frey aesthesiometer test. For some animals, sciatic-tibial motor nerve conduction velocity, tail sensory nerve conduction velocity and eye pattern electroretinogram were measured. At the end of the experiments, islets were isolated to detect glucose-stimulated insulin secretion, ATP content and extent of apoptosis. The NAD/NADH ratio in islets and retinas was evaluated. Surviving retinal ganglion cells were estimated by immunohistochemistry. RESULTS We found that the Wld(S) gene is expressed in islets and protects beta cells against multiple low doses of STZ by increasing the NAD/NADH ratio, maintaining the ATP concentration, and reducing apoptosis. Consistently, significantly higher insulin concentrations, lower blood glucose concentrations, and better glucose tolerance were observed in Wld(S) mice compared with WT mice after STZ treatment. Furthermore, Wld(S) alleviated abnormal sensory responses, nerve conduction, retina dysfunction and reduction of surviving retinal ganglion cells in STZ-induced diabetic models. CONCLUSIONS/INTERPRETATION We provide the first evidence that expression of the Wld(S) gene decreases beta cell destruction and preserves islet function in STZ-induced diabetes, thus revealing a novel protective strategy for diabetic models.
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Affiliation(s)
- S S Zhu
- Atherosclerosis Research Centre, Nanjing Medical University, 140 Hanzhong Road, Nanjing 210029, People's Republic of China
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Liu L, Liu JL, Srikant CB. Reg2 protects mouse insulinoma cells from streptozotocin-induced mitochondrial disruption and apoptosis. Growth Factors 2010; 28:370-8. [PMID: 20919961 DOI: 10.3109/08977194.2010.504721] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We reported previously that pancreas-specific ablation of IGF-I in mice induced an increased expression of regenerating family proteins Reg2 and Reg3β in the pancreas and protected them from streptozotocin (Stz)-induced β-cell damage. We, therefore, assessed the effect of ectopically introduced Reg2 on Stz-induced apoptosis in MIN6 mouse insulinoma cells and report here that Reg2 protects MIN6 cells from Stz-induced apoptosis by attenuating its ability to disrupt mitochondrial membrane integrity, activate caspase-3 and promote poly-ADP ribose polymerase cleavage, and induce apoptosis. These changes correlated with suppression of c-jun N-terminal kinase (JNK) phosphorylation by Stz. Reg2 inhibited Stz-induced proapoptotic events as well as the inactivation of JNK. Inclusion of chemical inhibitor of JNK to Reg2 expressing cells rendered them sensitive to Stz. These data demonstrate that Reg2 protects insulin-producing cells against Stz-induced apoptosis by interfering with its cytotoxic signaling upstream of the intrinsic proapoptotic events by preventing its ability to inactivate JNK.
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Affiliation(s)
- Lu Liu
- Fraser Laboratories, McGill University Health Centre and Royal Victoria Hospital, Montreal, Quebec, Canada H3A 1A1
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Poly(ADP-ribose) polymerase-1 (PARP-1) and its therapeutic implications. Vascul Pharmacol 2010; 53:77-87. [DOI: 10.1016/j.vph.2010.06.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 05/03/2010] [Accepted: 06/16/2010] [Indexed: 01/24/2023]
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Johnston APW, Campbell JE, Found JG, Riddell MC, Hawke TJ. Streptozotocin induces G2 arrest in skeletal muscle myoblasts and impairs muscle growth in vivo. Am J Physiol Cell Physiol 2006; 292:C1033-40. [PMID: 17092995 DOI: 10.1152/ajpcell.00338.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Streptozotocin (STZ) is used extensively to induce pancreatic beta-cell death and ultimately diabetes mellitus in animal models. However, the direct effects of STZ on muscle are largely unknown. To delineate the effects of STZ from the effects of hypoinsulinemia/hyperglycemia, we injected young rats with 1) saline (control), 2) STZ (120 mg/kg) or 3) STZ and insulin (STZ-INS; to maintain euglycemia). STZ rats demonstrated significantly elevated blood glucose throughout the 48-h protocol, while control and STZ-INS rats were euglycemic. Body mass increased in control (13 +/- 4 g), decreased by 19 +/- 2 g in STZ and remained unchanged in STZ-INS rats (-0.3 +/- 2 g). Cross-sectional areas of gastrocnemius muscle fibers were smaller in STZ vs. control (1,480 +/- 149 vs. 1,870 +/- 40 microm(2), respectively; P < 0.05) and insulin treatment did not rescue this defect (STZ-INS: 1,476 +/- 143 microm(2)). Western blot analysis revealed a detectable increase in ubiquitinated proteins in the STZ skeletal muscles compared with control and STZ-INS. To further define the effects of STZ on skeletal muscle, independent of hyperglycemia, myoblasts were exposed to varying doses of STZ (0.25-3.0 mg/ml) in vitro. Both acute and chronic exposures of STZ significantly impaired proliferative capacity in a dose-dependent manner. Within STZ-treated myoblasts, increased reactive oxygen species was associated with significant G(2)/M phase cell-cycle arrest. Taken together, our findings show that the effects of STZ are not beta-cell specific and reveal that STZ should not be used for studies examining diabetic myopathy.
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Affiliation(s)
- Adam P W Johnston
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada M3J 1P3
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Szabó C. Roles of poly(ADP-ribose) polymerase activation in the pathogenesis of diabetes mellitus and its complications. Pharmacol Res 2005; 52:60-71. [PMID: 15911334 DOI: 10.1016/j.phrs.2005.02.015] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Accepted: 02/01/2005] [Indexed: 11/28/2022]
Abstract
Activation of poly(ADP-ribose) polymerase (PARP) plays a role in the pathogenesis of beta-cell necrosis that occurs in response to autoimmune disease associated with Type I diabetes. In addition, PARP activation also plays a role in the pathogenesis of endothelial injury that underlies the ethiology of various diabetic complications (vasculopathy, cardiomyopathy, retinopathy, neuropathy), which develop on the basis of chronically elevated circulating glucose levels in diabetes. Both during the pathogenesis of diabetes and during the pathogenesis of diabetic complications, free radical and oxidant production leads to DNA strand-breakage which activates the nuclear enzyme PARP and initiates an energy consuming, inefficient cellular metabolic cycle with transfer of the ADP-ribosyl moiety of NAD+ to protein acceptors. These processes lead to the functional impairment of the affected cells (beta-cells or vascular endothelial cells, respectively). PARP also promotes the activation of various pro-inflammatory signal transduction pathways. During the last two decades, a growing number of experimental studies demonstrated the beneficial effects PARP inhibition in various models of diabetes and diabetic complications. The current review provides an overview of the experimental evidence implicating PARP as a causative factor in the pathogenesis of diabetes and diabetic complications in vitro and in vivo.
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Affiliation(s)
- Csaba Szabó
- Inotek Pharmaceuticals Corporation, Suite 419 E, 100 Cummings Center, Beverly, MA 01915, USA.
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Babaya N, Ikegami H, Fujisawa T, Nojima K, Itoi-Babaya M, Inoue K, Ohno T, Shibata M, Ogihara T. Susceptibility to streptozotocin-induced diabetes is mapped to mouse chromosome 11. Biochem Biophys Res Commun 2005; 328:158-64. [PMID: 15670764 DOI: 10.1016/j.bbrc.2004.12.149] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Indexed: 10/26/2022]
Abstract
To study the contribution of beta-cell vulnerability to susceptibility to diabetes, we studied beta-cell vulnerability to a single high dose of streptozotocin (STZ) in an animal model of type 2 diabetes, the NSY mouse, a sister strain of the STZ-sensitive NOD mouse, in comparison with the STZ-resistant C3H mouse. NSY mice were found to be extremely sensitive to STZ. Introgression of a single Chr 11, where STZ-sensitivity was mapped in the NOD mouse, from NSY mice converted STZ-resistant C3H mice to STZ-sensitive. Two nucleotide substitutions were identified in the nucleoredoxin gene, a positional and functional candidate gene for STZ-induced diabetes on Chr 11. These data, together with the co-localization of type 1 (Idd4) and type 2 (Nidd1n) susceptibility genes on Chr 11, suggest that the intrinsic vulnerability of pancreatic beta cells is determined by a gene or genes on Chr 11, which may also contribute to susceptibility to spontaneous diabetes.
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Affiliation(s)
- Naru Babaya
- Department of Geriatric Medicine, Osaka University Graduate School of Medicine, Suita, Japan
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Aspord C, Rome S, Thivolet C. Early events in islets and pancreatic lymph nodes in autoimmune diabetes. J Autoimmun 2005; 23:27-35. [PMID: 15236750 DOI: 10.1016/j.jaut.2004.03.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2003] [Accepted: 03/08/2004] [Indexed: 11/23/2022]
Abstract
The specific contributions of islet cell microenvironment during the development of autoimmune type 1 diabetes remain unclear. The aims of this study were to identify early immune-driven abnormalities in islets and pancreatic lymph nodes of NOD mice by cDNA arrays. We compared gene expression profiles of purified islets and pancreatic lymph nodes of 4-week-old NOD mice to NOD-SCID and BALB/c mice. To further characterize the networks implicated in beta-cell destruction, we also performed a time-course analysis using islets and pancreatic lymph nodes of NOD mice from 2 to 25 weeks of age. We found consistent changes by cDNA arrays and RT-PCR analyses among islet genes before the detection of CD3+ T cells in the islet periphery associated with dendritic cell attraction, lymphocyte homing, and apoptosis. In contrast to IL-1, TYNFSF13B and osteopontin genes which were specifically activated, the immunoregulatory cytokine IL-11 was poorly detected in NOD islets and pancreatic lymph nodes. Genes involved in angiogenesis were also specifically activated in NOD islets of 2 and 4 weeks of age. The present time-course macroarray and RT-PCR analyses provides a detailed picture of the different genes involved in autoimmune diabetes and illustrates the importance of islet cell microenvironment that prepares the late beta-cell destruction.
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Affiliation(s)
- Caroline Aspord
- INSERM 449, Mécanismes moléculaires du diabète, Faculté de médecine Laennec, rue Guillaume Parradin, 69008 Lyon, France
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Yalowitz JA, Xiao S, Biju MP, Antony AC, Cummings OW, Deeg MA, Jayaram HN. Characterization of human brain nicotinamide 5'-mononucleotide adenylyltransferase-2 and expression in human pancreas. Biochem J 2004; 377:317-26. [PMID: 14516279 PMCID: PMC1223862 DOI: 10.1042/bj20030518] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2003] [Revised: 09/17/2003] [Accepted: 09/29/2003] [Indexed: 11/17/2022]
Abstract
NMNAT (nicotinamide 5'-mononucleotide adenylyltransferase; EC 2.7.7.1) catalyses the transfer of the adenylyl group from ATP to NMN to form NAD. We have cloned a novel human NMNAT cDNA, designated hNMNAT-2, from human brain. The cDNA contains a 924 bp open reading frame that encodes a 307 amino acid peptide that was expressed as a histidine-patch-containing thioredoxin fusion protein. Expressed hNMNAT-2 shared only 35% amino acid sequence homology with the human NMNAT enzyme (hNMNAT-1), but possessed enzymic activity comparable with hNMNAT-1. Using human genomic databases, hNMNAT-2 was localized to chromosome 1q25 within a 171 kb gene, whereas hNMNAT-1 is on chromosome 1p32-35. Northern blot analysis revealed highly restricted expression of hNMNAT-2 to brain, heart and muscle tissues, which contrasts with the wide tissue expression of hNMNAT-1; different regions of the brain exhibited differential expression of hNMNAT-2. Substitution mutations of either of two invariant residues, His-24 or Trp-92, abolished enzyme activity. Anti-peptide antibody to a unique epitope within hNMNAT-2 was produced, and immunohistochemical analysis of sections of normal adult human pancreas revealed that hNMNAT-2 protein was markedly expressed in the islets of Langerhans. However, the pancreatic exocrine cells exhibited weak expression of hNMNAT-2 protein. Sections of pancreas from insulinoma patients showed strong expression of hNMNAT-2 protein in the insulin-producing tumour cells, whereas acinar cells exhibited relatively low expression of hNMNAT-2 protein. These data suggest that the unique tissue-expression patterns of hNMNAT-2 reflect distinct functions for the isoforms in the regulation of NAD metabolism.
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Affiliation(s)
- Joel A Yalowitz
- Department of Biochemistry and Molecular Biology, Richard L. Roudebush Veterans Affairs Medical Center - 151, 1481 West Tenth Street, Indianapolis, IN 46202, USA
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Suarez-Pinzon WL, Mabley JG, Power R, Szabó C, Rabinovitch A. Poly (ADP-ribose) polymerase inhibition prevents spontaneous and recurrent autoimmune diabetes in NOD mice by inducing apoptosis of islet-infiltrating leukocytes. Diabetes 2003; 52:1683-8. [PMID: 12829633 DOI: 10.2337/diabetes.52.7.1683] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Poly (ADP-ribose) polymerase (PARP) is a nuclear enzyme that consumes NAD in response to DNA strand breaks. The PARP inhibitor nicotinamide prevents NAD consumption and protects islet beta-cells from chemically induced necrosis but not cytokine-induced apoptosis. Therefore, it is unclear how nicotinamide protects NOD mice from autoimmune diabetes in which apoptosis is the mode of beta-cell death. To investigate the mechanism of diabetes prevention by PARP inhibition, we studied the effects of a novel, potent PARP inhibitor, PJ34, a phenanthridinone derivative, on diabetes development in NOD mice and on diabetes recurrence in diabetic NOD mice transplanted with syngeneic islets. PJ34 administration from age 5 or 15 weeks significantly decreased insulitis, beta-cell destruction and diabetes incidence, and protection from diabetes continued for 12 weeks after PJ34 therapy was stopped. Similarly, syngeneic islet graft survival was prolonged and outlasted therapy in PJ34-treated mice. Immunohistochemical studies revealed significantly fewer leukocytes in islet grafts of PJ34-treated mice, together with increased apoptosis of these cells and decreased expression of the T helper 1-type cytokine interferon (IFN)-gamma. These results suggest that PARP inhibition protects against autoimmune beta-cell destruction in NOD mice by inducing apoptosis of islet-infiltrating leukocytes and decreasing IFN-gamma expression in the islets.
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Abstract
Type 1 (insulin-dependent) diabetes mellitus results from selective immune-mediated destruction of pancreatic islet beta cells. Strategies to prevent or reverse the development of diabetes can be divided into three groups, depending on whether they focus on beta-cell protection, regeneration or replacement. Prevention of immune beta-cell destruction involves either halting the immune attack directed against beta cells or making beta cells better able to withstand immune attack, for example, by making them resistant to free radical damage. The recent identification of beta-cell growth factors and development of stem cell technologies provides an alternative route to the reversal of diabetes, namely beta-cell regeneration. Interestingly, stem cell-derived islets appear to be less sensitive to recurrent immune destruction that is normally seen in response to islet transplantation. The last alternative is beta-cell replacement or substitution. This covers a wide range of interventions including human whole pancreas transplantation, xenotransplantation, genetically modified beta cells, mechanical insulin sensing and delivery devices, and the artificial pancreas. This review describes recent advances in each of these research areas and aims to provide clinicians with an idea of where and when an effective strategy to prevent or reverse diabetes development will become available.
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Affiliation(s)
- Nikolai Petrovsky
- Autoimmunity Research Unit, Canberra Hospital and Medical Informatics Centre, University of Canberra, ACT, Australia.
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Current literature in diabetes. Diabetes Metab Res Rev 2002; 18:419-26. [PMID: 12397584 DOI: 10.1002/dmrr.247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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