Adenosine Diphosphate Ribosylation Research Articles

Engineered Anti-GPC3 Immunotoxin, HN3-ABD-T20, Produces Regression in Mouse Liver Cancer Xenografts Through Prolonged Serum Retention.

Treatment of hepatocellular carcinomas using our glypican-3 (GPC3)-targeting human nanobody (HN3) immunotoxins causes potent tumor regression by blocking protein synthesis and down-regulating the Wnt signaling pathway. However, immunogenicity and a short serum half-life may limit the ability of immunotoxins to transition to the clinic. To address these concerns, we engineered HN3-based immunotoxins to contain various deimmunized Pseudomonas exotoxin (PE) domains. This included HN3-T20, which was modified to remove T-cell epitopes and contains a PE domain II truncation. We compared them to our previously reported B-cell deimmunized immunotoxin (HN3-mPE24) and our original HN3-immunotoxin with a wild-type PE domain (HN3-PE38). All of our immunotoxins displayed high affinity to human GPC3, with HN3-T20 having a KD value of 7.4nM. HN3-T20 retained 73% enzymatic activity when compared with the wild-type immunotoxin in an adenosine diphosphate-ribosylation assay. Interestingly, a real-time cell growth inhibition assay demonstrated that a single dose of HN3-T20 at 62.5ng/mL (1.6nM) was capable of inhibiting nearly all cell proliferation during the 10-day experiment. To enhance HN3-T20's serum retention, we tested the effect of adding a streptococcal albumin-binding domain (ABD) and a llama single-domain antibody fragment specific for mouse and human serum albumin. For the detection of immunotoxin in mouse serum, we developed a highly sensitive enzyme-linked immunosorbent assay and found that HN3-ABD-T20 had a 45-fold higher serum half-life than HN3-T20 (326 minutes vs. 7.3minutes); consequently, addition of an ABD resulted in HN3-ABD-T20-mediated tumor regression at 1mg/kg. These data indicate that ABD-containing deimmunized HN3-T20 immunotoxins are high-potency therapeutics ready to be evaluated in clinical trials for the treatment of liver cancer.

Outbreak of an Uncommon Rifampin-resistant blaNDM-1Citrobacter amalonaticus Strain in a Digestive Rehabilitation Center: The Putative Role of Rifaximin.

We describe a sudden 2-week outbreak due to a blaNDM-1Citrobacter amalonaticus strain in a 22-bed digestive rehabilitation center. Three of the 5 colonized patients received long-term rifaximin treatment to prevent hepatic encephalopathy. The strains were genotypically identical, phenotypically resistant to rifampin, and harbored arr-3, a rifampin adenosine diphosphate-ribosyl transferase.

Supramolecular Toxin Complexes for Targeted Pharmacological Modulation of Polymorphonuclear Leukocyte Functions.

The targeted pharmacological modulation of polymorphonuclear leukocytes (PMNs) is of major medical interest. These innate immune cells play a central role in the defense against pathogenic microorganisms. However, their excessive chemotactic recruitment into tissues after traumatic injury is detrimental due to local and systemic inflammation. Rho-GTPases, being the master regulators of the actin cytoskeleton, regulate migration and chemotaxis of PMNs, are attractive pharmacological targets. Herein, supramolecular protein complexes are assembled in a "mix-and-match" approach containing the specific Rho-inhibiting clostridial C3 enzyme and three PMN-binding peptides using an avidin platform. Selective delivery of the C3 Rho-inhibitor with these complexes into the cytosol of human neutrophil-like NB-4 cells and primary human PMNs ex vivo is demonstrated, where they catalyze the adenosine diphosphate (ADP) ribosylation of Rho and induce a characteristic change in cell morphology. Notably, the complexes do not deliver C3 enzyme into human lung epithelial cells, A549 lung cancer cells, and immortalized human alveolar epithelial cells (hAELVi), demonstrating their cell type-selectivity. The supramolecular complexes represent attractive molecular tools to decipher the role of PMNs in infection and inflammation or for the development of novel therapeutic approaches for diseases that are associated with hyperactivity and reactivity of PMNs such as post-traumatic injury.

Adenylyl Cyclase 6 Expression Is Essential for Cholera Toxin-Induced Diarrhea.

Cholera toxin (CT)-induced diarrhea is mediated by cyclic adenosine monophosphate (cAMP)-mediated active Cl- secretion via the cystic fibrosis transmembrane conductance regulator (CFTR). Although the constitutive activation of adenylyl cyclase (AC) in response to CT is due to adenosine diphosphate ribosylation of the small G protein α-subunit activating CFTR with consequent secretory diarrhea, the AC isoform(s) involved remain unknown. We generated intestinal epithelial cell-specific adenylyl cyclase 6 (AC6) knockout mice to study its role in CT-induced diarrhea. AC6 messenger RNA levels were the highest of all 9 membrane-bound AC isoforms in mouse intestinal epithelial cells. Intestinal epithelial-specific AC6 knockout mice (AC6loxloxVillinCre) had undetectable AC6 levels in small intestinal and colonic epithelial cells. No significant differences in fluid and food intake, plasma electrolytes, intestinal/colon anatomy and morphology, or fecal water content were observed between genotypes. Nevertheless, CT-induced fluid accumulation in vivo was completely absent in AC6loxloxVillinCre mice, associated with a lack of forskolin- and CT-induced changes in the short-circuit current (ISC) of the intestinal mucosa, impaired cAMP generation in acutely isolated small intestinal epithelial cells, and significantly impaired apical CFTR levels in response to forskolin. AC6 is a novel target for the treatment of CT-induced diarrhea.

Plasma membrane proteome analysis identifies a role of barley membrane steroid binding protein in root architecture response to salinity.

Although the physiological consequences of plant growth under saline conditions have been well described, understanding the core mechanisms conferring plant salt adaptation has only started. We target the root plasma membrane proteomes of two barley varieties, cvs. Steptoe and Morex, with contrasting salinity tolerance. In total, 588 plasma membrane proteins were identified by mass spectrometry, of which 182 were either cultivar or salinity stress responsive. Three candidate proteins with increased abundance in the tolerant cv. Morex were involved either in sterol binding (a GTPase-activating protein for the adenosine diphosphate ribosylation factor [ZIGA2], and a membrane steroid binding protein [MSBP]) or in phospholipid synthesis (phosphoethanolamine methyltransferase [PEAMT]). Overexpression of barley MSBP conferred salinity tolerance to yeast cells, whereas the knock-out of the heterologous AtMSBP1 increased salt sensitivity in Arabidopsis. Atmsbp1 plants showed a reduced number of lateral roots under salinity, and root-tip-specific expression of barley MSBP in Atmsbp1 complemented this phenotype. In barley, an increased abundance of MSBP correlates with reduced root length and lateral root formation as well as increased levels of auxin under salinity being stronger in the tolerant cv. Morex. Hence, we concluded the involvement of MSBP in phytohormone-directed adaptation of root architecture in response to salinity.

Extranuclear Sirtuins and Metabolic Stress.

Extranuclear sirtuins in cytosol (SIRT2) and mitochondria (SIRT3, SIRT4, and SIRT5) are key regulators of metabolic enzymes and the antioxidative defense mechanisms. They play an important role in the adjustment of metabolic pathways in alterations of the nutritional status. Recent Advances: Recent studies have shown that in addition to lysine deacetylation, sirtuins catalyze several different lysine deacylation reactions, removal of lipid modifications, and adenosine diphosphate-ribosylation. Large-scale studies have revealed hundreds of target proteins regulated by different sirtuin modifications. Sensing of the metabolic state and regulation of the sirtuin function and expression are critical components of the machinery, optimizing cellular functions in the switch from fed to fasting condition. Overfeeding, obesity, and metabolic diseases cause metabolic stress that dysregulates the sirtuins, which may play a role in the pathogenesis and complications of metabolic diseases such as type 2 diabetes, fatty liver disease, and cardiac diseases. In the current review, we will discuss the significance of the extranuclear sirtuins as metabolic regulators and in protection against the reactive oxygen species, and also how these sirtuins are regulated by metabolic status and their putative role in metabolic diseases. To efficiently utilize sirtuins as drug targets for treatment of the metabolic diseases, better understanding of the sirtuin functions, targets, regulation, and cross talk is needed. Furthermore, more studies in humans are needed to confirm the many observations mainly made in animal and cell models so far. Antioxid. Redox Signal. 28, 662-676.

Abstract 2212: Protein engineering of the decapping enzyme NudT16 enhances its ability to hydrolyze protein-conjugated ADP-ribose for post-translational site identification via mass spectrometry

Abstract During nonhomologous end joining of DNA follow double-stranded breaks, one common signaling response is the adenosine diphosphate ribosylation (ADP-ribosylation) of recruiter scaffold proteins. ADP-ribosylation is a post-translational modification (PTM) that occurs on aspartate, glutamate, lysine, arginine and cysteine on proteins and is mediated chiefly by polyadenosine ribose polymerases (PARP). Using NAD+ as its substrate, PARP transfers an ADP-ribose onto another protein, releasing a nicotinamide ring in the process; this modification presents as a mono-ADP-ribosylation (MARylation) or poly-ADP-ribosylation (PARylation). While site identification of MARylated protein can be achieved through tandem MS/MS and searching for peptides whose spectra have been shifted by 541.0611 Da, a similar approach for PARylated protein is confounded by the variable length and branching of its PTM. To this end, ADP-ribosylated protein is normally incubated with a snake venom phosphodiesterase (SVP) to leave a standardized phosphoribose tag of 212.0086 Da. It has been shown that a recombinantly-expressed Nudix protein NudT16 provides a cost-effective alternative to SVP to process ADP-ribosylated protein. NudT16 in the cell normally decaps small nucleolar RNA. Our studies here sought to utilize the x-ray crystallographic structure of NudT16 in complex with ADP-ribose in guiding rational design mutations to enhance binding of our desired ADP-ribose substrate and to widen the hydrolase’s active site to better accommodate a protein-conjugated ADP-ribose. Mutants have demonstrated improved catalytic efficiency for ADP-ribose hydrolysis. Radiolabeled immunoassays of PARylated protein concur with these kinetic experiments by showing a reduction of radiolabeled PARP. Rational design of a ADP-ribose-hydrolyzing NudT16 with comparable catalytic efficiency to SVP eases lead discovery of biological mechanisms that are mediated through ADP-ribosylation such as DNA repair. Citation Format: Puchong Thirawatananond, Robert L. McPherson, Jasmine K. Malhi, Anthony K. Leung, Sandra B. Gabelli. Protein engineering of the decapping enzyme NudT16 enhances its ability to hydrolyze protein-conjugated ADP-ribose for post-translational site identification via mass spectrometry [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2212. doi:10.1158/1538-7445.AM2017-2212

RASSF4 controls SOCE and ER-PM junctions through regulation of PI(4,5)P2.

RAS association domain family 4 (RASSF4) is involved in tumorigenesis and regulation of the Hippo pathway. In this study, we identify new functional roles of RASSF4. First, we discovered that RASSF4 regulates store-operated Ca2+ entry (SOCE), a fundamental Ca2+ signaling mechanism, by affecting the translocation of the endoplasmic reticulum (ER) Ca2+ sensor stromal interaction molecule 1 (STIM1) to ER-plasma membrane (PM) junctions. It was further revealed that RASSF4 regulates the formation of ER-PM junctions and the ER-PM tethering function of extended synaptotagmins E-Syt2 and E-Syt3. Moreover, steady-state PM phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2) levels, important for localization of STIM1 and E-Syts at ER-PM junctions, were reduced in RASSF4-knockdown cells. Furthermore, we demonstrated that RASSF4 interacts with and regulates the activity of adenosine diphosphate ribosylation factor 6 (ARF6), a small G protein and upstream regulator of type I phosphatidylinositol phosphate kinases (PIP5Ks) and PM PI(4,5)P2 levels. Overall, our study suggests that RASSF4 controls SOCE and ER-PM junctions through ARF6-dependent regulation of PM PI(4,5)P2 levels, pivotal for a variety of physiological processes.

SIRT1 gene polymorphisms and its protein level in colorectal cancer

Colorectal cancer (CRC) is a major cause of mortality and morbidity, and accounts for over 9% of cancer incidence worldwide. Nuclear localized silent information regulator 2 homolog 1 (SIRT1) gene exerts its effects via modulation of histone and non-histone targets. SIRT1 gene functions in the cell via histone deacetylase (HDAC) and/or adenosine diphosphate ribosyl transferase (ADPRT) enzymatic activity. The aim of this work is to study the relationship between SIRT1 polymorphism and its protein level in colorectal cancer patients in comparison to control cases. This study includes two group, thirty healthy subjects (control group) and one hundred CRC patients. SIRT-1 serum level was measured in both the groups by ELISA and gene polymorphisms of rs12778366, rs375891 and rs3740051were detected by real time PCR. For CRC patients clinical data was collected including tumor size, tumor grade, tumor site, obesity. CRC patients showed a significant increase in the mean level of serum SIRT-1 compared to control group (P<0.001). Mean serum level of SIRT-1 showed a significant increase in patients with tumor size ≥5cm compared to the size <5cm (P<0.05). In CRC patients, the percentage of T allele of rs12778366 was significantly lower than controls, CC genotype and C allele C of rs375891 were significantly higher than control group. In CRC patients, the CC genotype of rs12778366, was 75% in the rectosigmoid colon and 25% in cecum & ascending colon. According to tumor size, the percentage of CC genotype was 87.5% in tumor size ≥5cm. ConclusionSerum level of SIRT-1 and T allele, C allele of rs12778366 and rs375891 respectively can be used as diagnostic markers for CRC patients.

Inhibition of Nicotinamide Phosphoribosyltransferase Induces Apoptosis in Estrogen Receptor-Positive MCF-7 Breast Cancer Cells.

PurposeTumor cells have increased turnover of nicotinamide adenine dinucleotide (NAD+), the main coenzyme in processes including adenosine diphosphate-ribosylation, deacetylation, and calcium mobilization. NAD+ is predominantly synthesized in human cells via the salvage pathway, with the first component being nicotinamide. Nicotinamide phosphoribosyltransferase (NAMPT) is the key enzyme in this pathway, and its chemical inhibition by FK866 has elicited antitumor effects in several preclinical models of solid and hematologic cancers. However, its efficacy in estrogen receptor (ER)-positive and human epidermal growth factor receptor 2-positive breast cancer cells has not been previously investigated. In this study, we aimed to deplete the NAD+ content of MCF-7 cells, a model cell line for ER-positive breast cancer, by inhibiting NAMPT in order to evaluate downstream effects on p53 and its acetylation, p21 and Bcl-2-associated X protein (BAX) expression, and finally, apoptosis in MCF-7 breast cancer cells.MethodsMCF-7 cells were cultured and treated with FK866. NAD+ levels in cells were determined colorimetrically. Levels of p53 and its acetylated form were determined by Western blotting. Expression of p21 and BAX was determined by real-time polymerase chain reaction. Finally, levels of apoptosis were assessed by flow cytometry using markers for annexin V and propidium iodide.ResultsFK866 treatment was able to increase p53 levels and acetylation, upregulate BAX and p21 expression, and induce apoptosis in MCF-7 cells. Addition of exogenous NAD+ to cells reversed these effects, suggesting that FK866 exerted its effects by depleting NAD+ levels.ConclusionResults showed that FK866 could effectively inhibit NAD+ biosynthesis and induce programmed cell death in MCF-7 cells, suggesting that NAMPT inhibitors may be useful for the treatment of ER-positive breast cancers.

A new histone tag

A common strategy organisms have for controlling biological processes in a cell is to decorate important proteins with a chemical tag, such as a phosphate, methyl, or acetyl group. One of the most complex and fragile of these so-called posttranslational modifications is known as adenosine diphosphate ribosylation, or ADPr. This modification is used by many pathogens, including the causative agent of cholera, which uses ADPr to orchestrate lysis of intestinal cells. In mammals, the tag is involved in DNA repair, and malfunctions in ADPr decoration can lead to cancer. Despite ADPr’s importance, researchers know little about its precise molecular mechanisms or the specific amino acids ADPr decorates. To remedy this situation, a team led by Ivan Matic of the Max Planck Institute for Biology of Ageing has developed a mass spectrometry technique to identify and quantify ADPr in cells (Nat. Chem. Biol. 2016, DOI: 10.1038/nchembio.2180). The method reveals that histone

An Overview of Chromatin-Regulating Proteins in Cells.

In eukaryotic cells, gene expressions on chromosome DNA are orchestrated by a dynamic chromosome structure state that is largely controlled by chromatin-regulating proteins, which regulate chromatin structures, release DNA from the nucleosome, and activate or suppress gene expression by modifying nucleosome histones or mobilizing DNA-histone structure. The two classes of chromatinregulating proteins are 1) enzymes that modify histones through methylation, acetylation, phosphorylation, adenosine diphosphate-ribosylation, glycosylation, sumoylation, or ubiquitylation and 2) enzymes that remodel DNA-histone structure with energy from ATP hydrolysis. Chromatin-regulating proteins, which modulate DNA-histone interaction, change chromatin conformation, and increase or decrease the binding of functional DNA-regulating protein complexes, have major functions in nuclear processes, including gene transcription and DNA replication, repair, and recombination. This review provides a general overview of chromatin-regulating proteins, including their classification, molecular functions, and interactions with the nucleosome in eukaryotic cells.

Differential Regulation of mTORC1 by Amino Acids

Organisms sense nutrient fluctuations and respond accordingly to control cell growth. When this process goes awry, the result can be detrimental, often leading to cancer. Central to this process is the mechanistic target of rapamycin (mTOR), a conserved kinase that is the main component of a protein complex termed mTOR complex 1 (mTORC1). mTORC1 activation is frequently observed in human cancers, and therapeutics that target mTORC1 have proven efficacious in clinical trials. Amino acids are the most potent stimuli for mTORC1 activation; however, the detailed molecular mechanisms are obscure, and importantly, the specific amino acids that regulate mTORC1 are unclear. Recently, we discovered that the amino acids, leucine and glutamine activate mTORC1 through two distinct signaling pathways involving the small G‐proteins RagA/B and the adenosine diphosphate ribosylation factor‐1 (Arf1), respectively. Importantly, we identified Arf1 as an essential component that specifically couples glutamine signaling to mTORC1 activation at the lysosome and independent of RagA/B. This is important because cancer cells have a high dependence on glutamine for growth and proliferation. Our results uncover a signaling cascade to mTORC1 activation independent of the Rag GTPases and suggest that mTORC1 is differentially regulated by specific amino acids.Support or Funding InformationCancer Prevention &amp; Research Institute of Texas (CPRIT)

Molecular Characterization and Drug Designing against Hypothetical Proteins of &lt;i&gt;Aspergillus fumigatus&lt;/i&gt; Af293 by Homology Modeling and Molecular Docking

Genome sequencing projects have led to an explosion of the huge amount of gene products in which many are of Hypothetical Proteins (HPs) with an unidentified function. Exploring and annotating the functions of HPs is important in ( Aspergillus fumigatus ) which is a pathogenic fungus that cause disease in individuals associated with immunodeficiency. In this study, sequence of five HPs of ( A. fumigatus Af293), which are nonhomologous to human, has been annotated from NCBI. Various computational tools such as three-dimensional (3D) structure was determined by means of homology modeling through Phyre2 and refined by ModRefiner. Then, the designed structure was evaluated with a structure validation program for instance ERRAT, PROCHECK, and QMEAN, for further structural analysis. The secondary structural features of proteins were determined through self-optimized prediction method with alignment and interacting networks by STRING. The receptor was analyzed by the active site and pocket finder tools. Docking studies were done through AutodockVina software. The 3D structure of five proteins was modeled and their ligand binding sites were identified. We have found domains and families of two proteins and these revealed that these proteins might have adenosine diphosphate-ribosylation activity, molecular chaperone, heat shock protein activity, plasminogen/hepatocyte growth factor activity, etc. Protein-ligand study of our predicted ligand shows the lowest energy of -7.4 kcal/mol for gi|66851587 and -6.7 kcal/mol for gi|66845370. Structural prediction of these proteins, detection of binding sites, and drug designing of current study will cover the way for further extensive investigation of these proteins in wet laboratory experiments and in that way assist drug design against Aspergillosis.

Abstract 417: Adenosine Diphosphate Ribosyl Cyclase via PI3K-Akt and FOXO3a Up-regulating MMP-9 to Enhance Vascular Smooth Muscle Cell Proliferation and Migration in Mice

The current study was designed to explore the mechanisms of vascular smooth muscle cell (VSMC) proliferation and migration induced by adenosine diphosphate ribosyl cyclase(ADPRC). In this study, 32 Male ApoE-/- mice(6 weeks old, 18-22g)on a C57BL/6J background were divided into four groups, which received normal chow (n=8, NC group), high-fat Western-type diet (n=8, 0.25% cholesterol, 21% fat,HFD group), high-fat Western-type diet,infusion of 2,2′-dihydroxyazobenzene(DHAB, a ADPRC inhibitor, 2mg/kg/day, n=8, HFD-DHAB group) intraperitoneally or high-fat Western-type diet,infusion of LY294002(a Inhibitor of Akt, 5mg/kg/d, n=8, HFD-LY group) intraperitoneally, for 10 weeks. 8 male C57BL/6J mice served as control. After 10 weeks, mice were anesthetized with chloral hydrate, aorta was removed and immediately frozen in liquid nitrogen. Aortic atherosclerotic lesions, VSMC proliferation and migration were assessed by histomorphological observation, smooth muscle actin-α(α-SMA)and proliferating cell nuclear antigen (PCNA) examination. ADPRC expression and alterations of Akt, FOXO3a, phospho-FOXO3a and MMP-9 were determined by RT-PCR, Western Blot, Immunohistochemistry or Immunofluorescence. The results showed that, in aortic atherosclerotic lesions derived from atherosclerotic mice of HFD group, an increased VSMC proliferation and migration, reflected by the up-regulation of α-SMA and PCNA expression, were observed followed by increased expression of ADPRC, Akt, FOXO3a, phospho-FOXO3a and MMP-9. The enhanced expression of ADPRC and followed alterations of FOXO3a, phospho-FOXO3a, MMP-9 as well as α-SMA, PCNA, VSMC proliferation and migration were absent in NC group and C57BL/6J control mice. Treatment with DHAB or LY294002 reversed VSMC proliferation, migration and expression of Akt, FOXO3a, phospho-FOXO3a and MMP-9 in HFD-DHAB and HFD-LY group. These data shows that high-fat Western-type diet induced ADPRC may via PI3K-Akt to phosphorylate FOXO3a up-regulating MMP-9 to enhance vascular smooth muscle cell proliferation and migration in mice.

Genome-wide association studies in biliary atresia.

Biliary atresia (BA) is a model complex disease resulting from interactions between multiple susceptibility loci and environmental factors. This perception is based on a heterogeneous phenotype extending beyond an absent extrahepatic bile duct to include gut and cardiovascular anomalies, and the association of BA with viral infections. Refractory jaundice and progression to cirrhosis shortly after birth can be fatal without surgical correction, and further suggests a pathogenesis during liver and bile duct development. Conclusive proof for a developmental origin would require documentation of disease progression in the perinatal or fetal liver, an impossible task for obvious reasons. We review three different sets of genome-wide association studies (GWAS) from three different cohorts of BA patients by three different groups of investigators, which address this knowledge gap. Knockdown of each susceptibility gene identified by GWAS in zebrafish embryos impairs excretion of bile from the liver, duplicating the characteristic diagnostic finding seen in affected children. This finding is associated with impaired intrahepatic biliary network formation in zebrafish morphants. Although distinct, these susceptibility genes share several functions including roles in mechanisms for organogenesis (glypican 1 or GPC1, and adenosine diphosphate ribosylation factor 6, or ARF6) or a greater expression in fetal liver than in adult liver (adducin 3 or ADD3). Together, these studies emphasize the importance of the human evidence, and present opportunities to map novel pathways which explain the phenotypic heterogeneity of BA.

Analysis of oxidative DNA damage and its repair in Polish patients with diabetes mellitus type 2: Role in pathogenesis of diabetic neuropathy

PurposeDistal symmetric polyneuropathy (DSPN) is common complication of type 2 diabetes (T2DM). In this work we investigated the role of oxidative damage in connection with particular polymorphisms of DNA repair genes and their repair capacity. Material/methodsMaterials constitute the peripheral blood of patients with T2DM with and without DSPN and control subjects without disturbance of the carbohydrate fraction. The study of gene polymorphisms which products take part in base excision repair (BER) pathway: 726 Val/Ala adenosine diphosphate ribosyl transferase (ADPRT), 324 His/Glu MutYhomolog (MUTYH) and 148 Asp/Glu human apurinic/apyrimidinic endonuclease (APE) was carried out using restriction fragment length polymorphism polymerase chain reaction (PCR-RFLP) method. The study of DNA damage induced by hydrogen peroxide and the efficiency of their repair was carried out using comet assay. ResultsNone of the 3 polymorphisms were associated with the risk of DSPN. However, in group of patients together with T2DM and T2DM/DSPN 726 Ala ADPRT allele was significantly susceptible to increased risk of T2DM (OR=1.59; 95% CI: 1.08–2.36). Investigation of DNA damage and repair revealed that T2DM patients have decreased ability to DNA repair. This capacity even drops down in the group of T2DM/DSPN patients compared to subjects with diabetes alone. ADPRT and APE polymorphisms were significantly associated with higher DNA damages (P<0.05) in heterozygous and mutant homozygous in correlation to homozygous wild type, but for MUTYH polymorphism relation was not confirmed. ConclusionsPathogenesis of T2DM and development of DSPN may be related to oxidative stress connected with BER gene polymorphisms.

Synthesis of well-defined adenosine diphosphate ribose oligomers.

The post-translational modification of proteins that is known as adenosine diphosphate ribosylation (ADPr) regulates a wide variety of important biological processes, such as DNA-damage repair and cellular metabolism. This modification is also involved in carcinogenesis and the process of aging. Therefore, a better understanding of the function of ADP-ribosylation is crucial for the development of novel therapeutics. To facilitate the elucidation of the biology of ADPr, the availability of well-defined fragments of poly(ADP-ribose) is essential. Herein we report a solid-phase synthetic approach for the preparation of ADP-ribose oligomers of exactly defined length. The methodology is exemplified by the first reported synthesis of an ADP-ribose dimer and trimer.

Metabolism. Differential regulation of mTORC1 by leucine and glutamine.

The mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) integrates environmental and intracellular signals to regulate cell growth. Amino acids stimulate mTORC1 activation at the lysosome in a manner thought to be dependent on the Rag small guanosine triphosphatases (GTPases), the Ragulator complex, and the vacuolar H+-adenosine triphosphatase (v-ATPase). We report that leucine and glutamine stimulate mTORC1 by Rag GTPase-dependent and -independent mechanisms, respectively. Glutamine promoted mTORC1 translocation to the lysosome in RagA and RagB knockout cells and required the v-ATPase but not the Ragulator. Furthermore, we identified the adenosine diphosphate ribosylation factor-1 GTPase to be required for mTORC1 activation and lysosomal localization by glutamine. Our results uncover a signaling cascade to mTORC1 activation independent of the Rag GTPases and suggest that mTORC1 is differentially regulated by specific amino acids.

Past and current topics on ADP-ribosylation reactions.

The milestone of Adenosine Diphosphate-ribosylation studies was the paper by Paul Mandel's group in 1960s, first describing a "sort" of polyadenylic acid synthesized upon addition of nicotinamide mononucleotide in rat liver nuclear extracts. Nicotinic Acid or Niacin is the precursor of Nicotinamide Adenin Dinucleotide. In 1960s this compound was known mainly as coenzyme of most redox processes in metabolism. The discovery of enzymes that covalently transfer Adenosine Diphosphate-ribose moiety of Nicotinamide Adenin Dinucleotide to acceptor proteins, thereby altering their function, or are able to synthesize cyclic Adenosine Diphosphate-ribose, has given rise to the era of one of the most studied and still surprising reversible post - translational modification reactions. Over 50 years, developing the research on Adenosine Diphosphate-ribosylation has provided the basis to interconnect several processes thought to be very distant each other, opening new perspectives in their regulation and in therapeutic intervention. Here a synthesis of the history and the main and recent goals reached studying Adenosine Diphosphate-ribose in all its features are provided by a series of reviews including the most advanced research.