Inorganic Pyrophosphatases:Study of Interest

Inorganic pyrophosphatases are enzymes that catalyze the hydrolysis of inorganic pyrophosphate to orthophosphate. These enzymes are divided into two groups: the soluble pyrophosphatases and the membrane pyrophosphatases. They vary in structure and each has a determined catalysis mechanism. Soluble pyrophosphatases are ubiquitous enzymes and play a key role in regulating the rate of pyrophosphate and balance in this sense, the biosynthetic reactions. Membrane pyrophosphatases are ion pumps, producing a proton or sodium gradient, and provide critical energy reserves to organisms, especially during stress conditions. Several studies have shown that these enzymes are involved in numerous disorders (diseases, fault cell growth···). However they are potential targets for the development of agents against parasites. This article consists of a description of the different types, structures, catalytic properties of inorganic pyrophosphatases and their involvement in cellular metabolism.

Expression of ectonucleotide pyrophosphatase-1 in end-plate chondrocytes with transforming growth factor beta 1 siRNA interference by cyclic mechanical tension

Background Ectonucleotide pyrophosphatase/phosphodiesterase （ENPP）-I is a membrane-bound protein that catalyzes the hydrolysis of extracellular nucleoside triphosphates to monophosphate and extracellular inorganic pyrophosphate （ePPi）. Mechanical stimulation regulates ENPP-1 expression. This study sought to investigate the changes in ENPP-1 expression after stimulation using cyclic mechanical tension （CMT）.

Counter-regulatory phosphatases TNAP and NPP1 temporally regulate tooth root cementogenesis

Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate （Pi） to mineral inhibitor pyrophosphate （PPi）, where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase （TNAP） and ectonucleotide pyrophosphatase/phosphodiesterase 1 （NPP1）. The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enppl null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enppl gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected.

Alkaline sphingomyelinase(NPP7) in hepatobiliary diseases: A field that needs to be closely studied

Alkaline sphingomyelinase cleaves phosphocholine from sphingomyelin, platelet-activating factor, lysophosphatidylcholine, and less effectively phosphatidyl-choline. The enzyme shares no structure similarities with acid or neutral sphingomyelinase but belongs to ectonucleotide pyrophosphatase/phosphodiesterase(NPP) family and therefore is also called NPP7 nowadays. The enzyme is expressed in the intestinal mucosa in many species and additionally in human liver. The enzyme in the intestinal tract has been extensively studied but not that in human liver. Studies on intestinal alkaline sphingomyelinase show that it inhibits colonic tumorigenesis and inflammation, hydrolyses dietary sphingomyelin, and stimulates cholesterol absorption. The review aims to summarize the current knowledge on liver alkaline sphingomyelinase in human and strengthen the necessity for close study on this unique human enzyme in hepatobiliary diseases.

ENPP1/PC-1 Gene K121Q Polymorphism Is Associated with Obesity in European Adult Populations: Evidence from A Meta-Analysis Involving 24 324 Subjects

Objective Findings from the previous studies have suggested a relationship between ectonucleotide pyrophosphatase /phosphodiesterase 1 （ENPP‐1） or plasma cell membrane glycoprotein 1 （PC‐1） gene single nucleotide polymorphism （K121Q, rs1044498） and genetic susceptibility to obesity. However, such relationship is not reproduced by some currently available studies. In this context, the present study is aimed to quantitatively analyze the association of K121Q variant with obesity in all published case‐control studies in European adult populations. Methods Published literature from PubMed, EMBASE, and ISI web of science databases were retrieved. The studies evaluating the association of ENPP1/PC1 gene K121Q polymorphism with obesity were included, in which sufficient data were presented to calculate the odds ratio （OR） with 95% confidence intervals （CIs）. Results Ten case‐control studies meeting the inclusion criteria identified a total of 24,324 subjects including 11,372 obese and 12,952 control subjects. The meta‐analysis results showed a statistically significant association of K121Q with obesity [OR （95%CI）： 1.25 （1.04‐1.52） P=0.021] under a recessive model of inheritance （QQ vs. KK＋KQ） without heterogeneity or publication bias. Conclusions The results from the present study have indicated that ENPP1/PC1 Q121 variant may increase the risk of obesity and that more well‐designed studies based on a larger population will be required to further evaluate the role of ENPP1/PC1 gene K121Q polymorphism in obesity and other related metabolic syndromes.

Role of genetic polymorphisms in hepatitis C virus chronic infection

AIM: To analyze the host genetics factors influencing the clinical course and the response to antiviral treatment in patients with chronic hepatitis C(CHC).METHODS: We conducted an electronic search on the Pub Med and MEDLINE(2000-2014) databases and Cochrane library(2000-2014). A total of 73 articles were retrieved and their data were extensively evaluated and discussed by the authors and then analyzed in this review article.RESULTS: Several studies associated polymorphisms in the interleukin 28 B gene on chromosome 19(19q13.13) with a spontaneous viral clearance in acute hepatitis C and with the response to pegylated interferon(PegIFN)-based treatment in chronic hepatitis C patients. Other investigations demonstrated that inosine triphosphate pyrophosphatase genetic variants protect hepatitis C virus-genotype-1 CHC patients from ribavirin-induced anemia, and other studies that a polymorphism in the patatin-like phospholipase domain-containing protein 3 was associated with hepatic steatosis in CHC patients. Although not conclusive, some investigations suggested that the vitamin D-associated polymorphisms play an important role in the achievement of sustained virologic response in CHC patients treated with Peg-IFN-based antiviral therapy. Several other polymorphisms have been investigated to ascertain their possible impact on the natural history and on the response to treatment in patients with CHC, but the data are preliminary and warrant confirmation. CONCLUSION: Several genetic polymorphisms seem to influence the clinical course and the response to antiviral treatment in patients with CHC, suggesting individualized follow up and treatment strategies.

The Ultracytochemical Effects of High Energy Shock Wave on Rabbit Liver

The ultracytochemical effects in the liver of rabbit undergoing high energy shock wave (HESW) were studied with electron microscope. The application of lanthanum as a tracer for ultrastructural study demonstrated that intracellular lanthanum could be observed, most of which entered the hepatocytes and its mitochondria. The lanthanum granules were also found to deposite in the zone of tight junctions of bile canaliculi, which indicated that the tight junctions had been damaged. The activities of succinate dehydrogenase (SDH) in liver cells, alkaline phosphatase (ALP) and thiamine pyrophosphatase (TPPase) on the wall of bile canaliculi became diminished obviously. Both the activites and localizations of TPPase had changed. Some TPPase from the damaged lysosome like vesicles and Golgi saccules of liver cells discharged into cytoplasm. TPPase reaction production in some bile canaliculi decreased. In the intercellular space of the liver cells and the tight junctions of bile canaliculi TPPase reaction could be seen. Ultrastructurally, the changes commonly seen were hydropic mitochondria and dilatation of rough endoplasmic reticulum. Serologic test demonstrated that there was an abnormal change of SGPT, SGOT and ALP. The results showed that HESW can damage the ultrastructure and function of liver.

Cell Stress by Phosphate of Two Protozoa Tetrahymena thermophila and Tetrahymena pyriformis

Phosphorus is one of the bioelements most needed as a compound cell by living organisms. Phosphorus is involved in several pathologies: in human with bone and kidney diseases, in mammals with metabolism disorder (glucose, insulin···), in microorganisms whose phosphorus is involved in cell growth. Phosphorus has various forms including pyrophosphate, a by-product of multiple pathways of biosynthesis. Enzymes that hydrolyze pyrophosphate are called inorganic pyrophosphatases (PPases). Two major types of inorganic pyrophosphatases are distinguished: the soluble pyrophosphatases (sPPases) and the membrane pyrophosphatases (mPPases or H+/Na+-PPases). They play a key role in the control of intracellular inorganic pyrophosphate level and produce an important ions gradient (H+ or Na+) to the cells. In this work, we primarily focused on the physiological study in a phosphate-poor medium of two models Tetrahymena thermophile and Tetrahymena pyriformis, following the mobility, the growth and the morphology of cells. Secondly, we evaluated the enzymatic activity of soluble and membrane pyrophosphatases in both species grown in the same complex medium. A decrease of cell growth is correlated with unusual morphologies and different mobility in the stress medium. The measurement of soluble and membrane inorganic pyrophosphatases activities also shows a decrease which illustrates the lack of phosphate found in the stress medium. Deficiency of phosphate is a limiting factor for protozoan growth. These results indicate that Tetrahymena can be used as a model of cellular stress and consists of a target to study inorganic pyrophosphatases for a better understanding of phosphate cycle in higher organisms.

Reductive lipid nanoparticles loaded with vinorelbine inhibit chemotherapy-induced invasion of cancer cells by modulating ENPP2

Cancer is a predominant culprit behind worldwide death and accounts for up to 10 million deaths every year.Chemotherapy is the primary therapeutic method employed for cancer in clinical settings and is essential in controlling tumor progression.Despite the advances in this field,tumor invasion and metastasis during treatment remain a significant cause of treatment failure.Nevertheless,the underlying mechanisms involving such a disappointing phenomenon are still not fully elucidated.Vinorelbine(VNB)extends the lifespan of many cancer patients in the clinic as an emerging chemotherapy drug approved by Food and Drug Administration(FDA).However,VNB-induced tumor metastasis is still an intractable problem,which may be closely related to the abnormal oxidative stress generated during VNB-mediated treatment.Hence,the study aims to construct a reductive nanosystem loaded with VNB,called VNB-VNP,to improve cancer cure rates and reduce tumor metastasis.With the reductive component vitamin E,VNB-VNP can effectively reduce oxidative stress and significantly outperform free VNB in preventing tumor progression.The transcriptome analysis shows that VNB-VNP can alleviate the over-expression of ectonucleotide pyrophosphatase/phosphodiesterase 2(ENPP2),which may be the main reason why VNB-VNP can inhibit tumor invasion and metastasis.Overall,the research designs a new platform for VNB treatment,which demonstrates promising efficacy in inhibiting neoplastic progression and identifies a new mechanism associated with VNB-induced tumor metastasis,which may offer several valuable references for enhancing chemotherapy efficacy in clinical anti-tumor therapy.

Inhibiting Self-Pollen:Self-Incompatibility in Papaver Involves Integration of Several Signaling Events

Cellular responses rely on signal perception and integration. A nice example of this is self incompatibility （SI）, which is an important mechanism to prevent inbreeding. It prevents self-fertilization by using a highly discriminatory cellular recognition and rejection mechanism. Most Sl systems are genetically specified by the S-locus, which has a pollen and a pistil S-component. A receptor-ligand interaction is used by Papaver rhoeas to control SI. S proteins encoded by the pistil part of the S-locus interact with incompatible pollen to achieve rapid inhibition of tip growth. The incompatible Sl interaction triggers a Ca^2＋-dependent signaling cascade. A number of Sl-specific events are triggered in incompatible pollen, including rapid depolymerization of the actin cytoskeleton; phosphorylation of soluble inorganic pyrophosphatases （SPPases）, Prp26.1; activation of a mitogen activated protein kinase, p56; programmed cell death （PCD） involving a caspase-3-1ike activity. These events contribute to prevent self-fertilizaUon. We are attempting to establish the functional significance of these events, and their possible involvement in integrating a coordinated signaling response. Here we describe the identification of these components shown to be involved in Sl, together with recent progress in identifying links between some of them. These data constitute the first steps in elucidating how SI signaling is integrated.

Design, synthesis and systematic evaluation of all possible cyclic dinucleotides (CDNs) that activate human stimulator of interferon genes (STING) variants

Cyclic dinucleotides(CDNs) are known to activate stimulator of interferon genes(STING) and induce type I interferon responses, therefor possess great potentials to be of immunotherapeutic value for cancers and infectious diseases. However, the existence of different single nucleotide polymorphism(SNP) of human STING(hSTING) gene poses an obstacle to achieve broad-spectrum activation by CDNs. We reported here the design and synthesis of a total of 36 CDNs, representing all structural variations, that contain four bases(A, G, C, U) and two linkage directions(2′-5′-linked and 3′-5′-linked phosphodiester).Through systematic evaluation of IFN-β induction with a dual-luciferase reporter assay, we discovered that wild type hSTING and two isoforms(HAQ and AQ) showed strong response while hSTING-R232 H and R293 Q exhibited the relatively weak response to CDNs stimulation. For the first time, we found that the c[G(2′,5′)U(2′,5′)] showed excellent activity against all five hSTING variants even equivalent to the endogenous ligand c[G(2′,5′)A(3′,5′)]. Furthermore, we have also demonstrated that 3′-3′CDNs with two 3′-5′ phosphodiesters showed higher serum and hydrolase stability than 2′-2′ CDNs with two 2′-5′ phosphodiesters and 2′-3′ CDNs with one 2′-5′ and one 3′-5′ phosphodiester. It is very interesting to note that 2′-2′ CDNs has been found for the first time to show strong activity. These findings will stimulate our exploration for the new functional role of CDNs, and provide guidelines to design CDNs based hSTING targeted drugs.

Characterization of Photorhabdus Virulence Cassette as a causative agent in the emerging pathogen Photorhabdus asymbiotica

The extracellular contractile injection systems(e CISs)are encoded in the genomes of a large number of bacteria and archaea.We have previously characterized the overall structure of Photorhabdus Virulence Cassette(PVC),a typical member of the e CIS family.PVC resembles the contractile tail of bacteriophages and exerts its action by the contraction of outer sheath and injection of inner tube plus central spike.Nevertheless,the biological function of PVC effectors and the mechanism of effector translocation are still lacking.By combining cryo-electron microscopy and functional experiments,here we show that the PVC effectors Pdp1(a new family of widespread d NTP pyrophosphatase effector in e CIS)and Pnf(a deamidase effector)are loaded inside the inner tube lumen in a"Peas in the Pod"mode.Moreover,we observe that Pdp1 and Pnf can be directly injected into J774 A.1 murine macrophage and kill the target cells by disrupting the d NTP pools and actin cytoskeleton formation,respectively.Our results provide direct evidence of how PVC cargoes are loaded and delivered directly into mammalian macrophages.

Pharmacogenetics of thiopurines

Polychemotherapeutic protocols for the treatment of pediatric acute lymphoblastic leukemia(ALL)always include thiopurines.Specific approaches vary in terms of drugs,dosages and combinations.Such therapeutic schemes,including risk-adapted intensity,have been extremely successful for children with ALL who have reached an outstanding 5-year survival of greater than 90%in developed countries.Innovative drugs such as the proteasome inhibitor bortezomib and the bi-specific T cell engager blinatumomab are available to further improve therapeutic outcomes.Nevertheless,daily oral thiopurines remain the backbone maintenance or continuation therapy.Pharmacogenetics allows the personalization of thiopurine therapy in pediatric ALL and clinical guidelines to tailor therapy on the basis of genetic variants in TPMT and NUDT15 genes are already available.Other genes of interest,such as ITPA and PACSIN2,have been implicated in interindividual variability in thiopurines efficacy and adverse effects and need additional research to be implemented in clinical protocols.In this review we will discuss current literature and clinical guidelines available to implement pharmacogenetics for tailoring therapy with thiopurines in pediatric ALL.