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American Journal of Physiology. Cell... Jul 2001Inorganic pyrophosphate (PP(i)) regulates certain intracellular functions and extracellular crystal deposition. PP(i) is produced, degraded, and transported by... (Review)
Review
Inorganic pyrophosphate (PP(i)) regulates certain intracellular functions and extracellular crystal deposition. PP(i) is produced, degraded, and transported by specialized mechanisms. Moreover, dysregulated cellular PP(i) production, degradation, and transport all have been associated with disease, and PP(i) appears to directly mediate specific disease manifestations. In addition, natural and synthetic analogs of PP(i) are in use or currently under evaluation as prophylactic agents or therapies for disease. This review summarizes recent developments in the understanding of how PP(i) is made and disposed of by cells and assesses the body of evidence for potentially significant physiological functions of intracellular PP(i) in higher organisms. Major topics addressed are recent lines of molecular evidence that directly link decreased and increased extracellular PP(i) levels with diseases in which connective tissue matrix calcification is disordered. To illustrate in depth the effects of disordered PP(i) metabolism, this review weighs the roles in matrix calcification of the transmembrane protein ANK, which regulates intracellular to extracellular movement of PP(i), and the PP(i)-generating phosphodiesterase nucleotide pyrophosphatase family isoenzyme plasma cell membrane glycoprotein-1 (PC-1).
Topics: Animals; Calcification, Physiologic; Calcinosis; Connective Tissue Cells; Diphosphates; Humans; Membrane Glycoproteins; Membrane Proteins; Molecular Structure; Phosphate Transport Proteins; Phosphoric Diester Hydrolases; Pyrophosphatases
PubMed: 11401820
DOI: 10.1152/ajpcell.2001.281.1.C1 -
Biochimica Et Biophysica Acta May 2003The ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) multigene family contains five members. NPP1-3 are type II transmembrane metalloenzymes characterized by a... (Review)
Review
The ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) multigene family contains five members. NPP1-3 are type II transmembrane metalloenzymes characterized by a similar modular structure composed of a short intracellular domain, a single transmembrane domain and an extracellular domain containing a conserved catalytic site. The short intracellular domain of NPP1 has a basolateral membrane-targeting signal while NPP3 is targeted to the apical surface of polarized cells. NPP4-5 detected by database searches have a predicted type I membrane orientation but have not yet been functionally characterized. E-NPPs have been detected in almost all tissues often confined to specific substructures or cell types. In some cell types, NPP1 expression is constitutive or can be induced by TGF-beta and glucocorticoids, but the signal transduction pathways that control expression are poorly documented. NPP1-3 have a broad substrate specificity which may reflect their role in a host of physiological and biochemical processes including bone mineralization, calcification of ligaments and joint capsules, modulation of purinergic receptor signalling, nucleotide recycling, and cell motility. Abnormal NPP expression is involved in pathological mineralization, crystal depositions in joints, invasion and metastasis of cancer cells, and type 2 diabetes. In this review we summarize the present knowledge on the structure and the physiological and biochemical functions of E-NPP and their contribution to the pathogenesis of diseases.
Topics: Amino Acid Sequence; Animals; Calcification, Physiologic; Catalytic Domain; Diabetes Mellitus, Type 2; Gene Expression Regulation, Enzymologic; Humans; Models, Biological; Multigene Family; Neoplasm Invasiveness; Nucleotides; Phosphoric Diester Hydrolases; Phylogeny; Pyrophosphatases; Signal Transduction; Substrate Specificity; Tissue Distribution
PubMed: 12757929
DOI: 10.1016/s0925-4439(03)00058-9 -
Mutation Research 2013Cellular nucleotide pools are often contaminated by base analog nucleotides which interfere with a plethora of biological reactions, from DNA and RNA synthesis to... (Review)
Review
Cellular nucleotide pools are often contaminated by base analog nucleotides which interfere with a plethora of biological reactions, from DNA and RNA synthesis to cellular signaling. An evolutionarily conserved inosine triphosphate pyrophosphatase (ITPA) removes the non-canonical purine (d)NTPs inosine triphosphate and xanthosine triphosphate by hydrolyzing them into their monophosphate form and pyrophosphate. Mutations in the ITPA orthologs in model organisms lead to genetic instability and, in mice, to severe developmental anomalies. In humans there is genetic polymorphism in ITPA. One allele leads to a proline to threonine substitution at amino acid 32 and causes varying degrees of ITPA deficiency in tissues and plays a role in patients' response to drugs. Structural analysis of this mutant protein reveals that the protein is destabilized by the formation of a cavity in its hydrophobic core. The Pro32Thr allele is thought to cause the observed dominant negative effect because the resulting active enzyme monomer targets both homo- and heterodimers to degradation.
Topics: Animals; Escherichia coli; Humans; Mice; Models, Molecular; Pharmacogenetics; Polymorphism, Genetic; Pyrophosphatases; Yeasts
PubMed: 23969025
DOI: 10.1016/j.mrrev.2013.08.001 -
Chembiochem : a European Journal of... Jul 2011Triptolide is a potent natural product, with documented antiproliferative, immunosuppressive, anti-inflammatory, antifertility, and antipolycystic kidney disease...
Triptolide is a potent natural product, with documented antiproliferative, immunosuppressive, anti-inflammatory, antifertility, and antipolycystic kidney disease effects. Despite a wealth of knowledge about the biology of this compound, direct intracellular target proteins have remained elusive. We synthesized a biotinylated photoaffinity derivative of triptolide, and used it to identify dCTP pyrophosphatase 1 (DCTPP1) as a triptolide-interacting protein. Free triptolide interacts directly with recombinant DCTPP1, and inhibits the enzymatic activity of this protein. Triptolide is thus the first dCTP pyrophosphatase inhibitor identified, and DCTPP1 is a biophysically validated target of triptolide.
Topics: DNA; Diterpenes; Epoxy Compounds; Gene Knockdown Techniques; HeLa Cells; Humans; Kinetics; Phenanthrenes; Photoaffinity Labels; Pyrophosphatases; Transfection
PubMed: 21671327
DOI: 10.1002/cbic.201100007 -
ChemMedChem Nov 2021Inhibition of membrane-bound pyrophosphatase (mPPase) with small molecules offer a new approach in the fight against pathogenic protozoan parasites. mPPases are absent...
Inhibition of membrane-bound pyrophosphatase (mPPase) with small molecules offer a new approach in the fight against pathogenic protozoan parasites. mPPases are absent in humans, but essential for many protists as they couple pyrophosphate hydrolysis to the active transport of protons or sodium ions across acidocalcisomal membranes. So far, only few nonphosphorus inhibitors have been reported. Here, we explore the chemical space around previous hits using a combination of screening and synthetic medicinal chemistry, identifying compounds with low micromolar inhibitory activities in the Thermotoga maritima mPPase test system. We furthermore provide early structure-activity relationships around a new scaffold having a pyrazolo[1,5-a]pyrimidine core. The most promising pyrazolo[1,5-a]pyrimidine congener was further investigated and found to inhibit Plasmodium falciparum mPPase in membranes as well as the growth of P. falciparum in an ex vivo survival assay.
Topics: Dose-Response Relationship, Drug; Humans; Molecular Structure; Pyrazoles; Pyrimidines; Pyrophosphatases; Structure-Activity Relationship
PubMed: 34459148
DOI: 10.1002/cmdc.202100392 -
International Journal of Developmental... Feb 2018There is growing evidence that over consumption of high-fat foods and insulin resistance may alter hippocampal-dependent cognitive function. To study the individual... (Review)
Review
There is growing evidence that over consumption of high-fat foods and insulin resistance may alter hippocampal-dependent cognitive function. To study the individual contributions of diet and peripheral insulin resistance to learning and memory, we used a transgenic mouse line that overexpresses ecto-nucleotide pyrophosphatase phosphodiesterase-1 in adipocytes, which inhibits the insulin receptor. Here, we demonstrate that a model of peripheral insulin resistance exacerbates high-fat diet induced deficits in performance on the Morris Water Maze task. This finding was then reviewed in the context of the greater literature to explore potential mechanisms including triglyceride storage, adiponectin, lipid composition, insulin signaling, oxidative stress, and hippocampal signaling. Together, these findings further our understanding of the complex relationship among peripheral insulin resistance, diet and memory.
Topics: Animals; Brain; Cognition Disorders; Diet, High-Fat; Insulin Resistance; Mice; Mice, Transgenic; Oxidative Stress; Phosphoric Diester Hydrolases; Pyrophosphatases
PubMed: 28373023
DOI: 10.1016/j.ijdevneu.2017.03.011 -
Biochemistry. Biokhimiia Mar 2000Recent progress in studies of the mode of action of cytoplasmic inorganic pyrophosphatases is mainly due to the analysis of a dozen and a half structures of the... (Review)
Review
Recent progress in studies of the mode of action of cytoplasmic inorganic pyrophosphatases is mainly due to the analysis of a dozen and a half structures of the apoenzyme, its complexes, and mutants. However, despite considerable research on the mechanism of action of these enzymes, many important problems remain unclear. Among them is the problem of active site interactions in oligomeric structures and their role in catalysis; this review focuses on this problem. The abundant experimental data requires generalization and comprehensive analysis. A characteristic feature of the spatial structure of inorganic pyrophosphatases is a flexible system of noncovalent interactions between protein groups penetrating the whole molecule of the oligomeric enzyme. Binding of metal ions, sulfate (an analog of the product of the enzymatic reaction), and affinity phosphorus-containing inhibitors at the active site or site-directed mutagenesis induce rearrangements in the set of hydrogen and ionic interactions, which change active site properties and in some instances, cause molecule asymmetry. In the trimeric form of Escherichia coli pyrophosphatase obtained by dissociation of a hexamer, active sites also interact with each other, which is manifested by negative cooperativity upon substrate binding. The association of trimers into the hexamer leads to perfect organization of active sites and to their coordinated functioning, probably due to the restoration of communication channels between the trimers.
Topics: Binding Sites; Gene Expression Regulation, Enzymologic; Inorganic Pyrophosphatase; Ligands; Models, Molecular; Point Mutation; Protein Conformation; Pyrophosphatases; X-Ray Diffraction
PubMed: 10739480
DOI: No ID Found -
Journal of Bone and Mineral Research :... Sep 2022Biallelic ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) deficiency induces vascular/soft tissue calcifications in generalized arterial calcification of...
Biallelic ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) deficiency induces vascular/soft tissue calcifications in generalized arterial calcification of infancy (GACI), and low bone mass with phosphate-wasting rickets in GACI survivors (autosomal hypophosphatemic rickets type-2). ENPP1 haploinsufficiency induces early-onset osteoporosis and mild phosphate wasting in adults. Both conditions demonstrate the unusual combination of reduced accrual of skeletal mineral, yet excess and progressive heterotopic mineralization. ENPP1 is the only enzyme that generates extracellular pyrophosphate (PPi), a potent inhibitor of both bone and heterotopic mineralization. Life-threatening vascular calcification in ENPP1 deficiency is due to decreased plasma PPi; however, the mechanism by which osteopenia results is not apparent from an understanding of the enzyme's catalytic activity. To probe for catalysis-independent ENPP1 pathways regulating bone, we developed a murine model uncoupling ENPP1 protein signaling from ENPP1 catalysis, Enpp1 mice. In contrast to Enpp1 mice, which lack ENPP1, Enpp1 mice have normal trabecular bone microarchitecture and favorable biomechanical properties. However, both models demonstrate low plasma Pi and PPi, increased fibroblast growth factor 23 (FGF23), and by 23 weeks, osteomalacia demonstrating equivalent phosphate wasting in both models. Reflecting findings in whole bone, calvarial cell cultures from Enpp1 mice demonstrated markedly decreased calcification, elevated transcription of Sfrp1, and decreased nuclear β-catenin signaling compared to wild-type (WT) and Enpp1 cultures. Finally, the decreased calcification and nuclear β-catenin signaling observed in Enpp1 cultures was restored to WT levels by knockout of Sfrp1. Collectively, our findings demonstrate that catalysis-independent ENPP1 signaling pathways regulate bone mass via the expression of soluble Wnt inhibitors such as secreted frizzled-related protein 1 (SFRP1), whereas catalysis dependent pathways regulate phosphate homeostasis through the regulation of plasma FGF23. © 2022 American Society for Bone and Mineral Research (ASBMR).
Topics: Animals; Bone and Bones; Catalysis; Familial Hypophosphatemic Rickets; Fibroblast Growth Factors; Mammals; Mice; Phosphates; Phosphoric Diester Hydrolases; Pyrophosphatases; Vascular Calcification; beta Catenin
PubMed: 35773783
DOI: 10.1002/jbmr.4640 -
The Plant Cell May 2018Inorganic pyrophosphate (PPi) is a phosphate donor and energy source. Many metabolic reactions that generate PPi are suppressed by high levels of PPi. Here, we...
Inorganic pyrophosphate (PPi) is a phosphate donor and energy source. Many metabolic reactions that generate PPi are suppressed by high levels of PPi. Here, we investigated how proper levels of cytosolic PPi are maintained, focusing on soluble pyrophosphatases (AtPPa1 to AtPPa5; hereafter PPa1 to PPa5) and vacuolar H-pyrophosphatase (H-PPase, AtVHP1/FUGU5) in In planta, five PPa isozymes tagged with GFP were detected in the cytosol and nuclei. Immunochemical analyses revealed a high abundance of PPa1 and the absence of PPa3 in vegetative tissue. In addition, the heterologous expression of each PPa restored growth in a soluble PPase-defective yeast strain. Although the quadruple knockout mutant plant showed no obvious phenotypes, H-PPase and PPa1 double mutants () exhibited significant phenotypes, including dwarfism, high PPi concentrations, ectopic starch accumulation, decreased cellulose and callose levels, and structural cell wall defects. Altered cell arrangements and weakened cell walls in the root tip were particularly evident in and were more severe than in Our results indicate that H-PPase is essential for maintaining adequate PPi levels and that the cytosolic PPa isozymes, particularly PPa1, prevent increases in PPi concentrations to toxic levels. We discuss phenotypes in relation to metabolic reactions and PPi homeostasis.
Topics: Arabidopsis; Cytosol; Diphosphates; Inorganic Pyrophosphatase; Pyrophosphatases; Vacuoles
PubMed: 29691313
DOI: 10.1105/tpc.17.00911 -
ENPP1, an Old Enzyme with New Functions, and Small Molecule Inhibitors-A STING in the Tale of ENPP1.Molecules (Basel, Switzerland) Nov 2019Ectonucleotide pyrophosphatase/phosphodiesterase I (ENPP1) was identified several decades ago as a type II transmembrane glycoprotein with nucleotide pyrophosphatase and... (Review)
Review
Ectonucleotide pyrophosphatase/phosphodiesterase I (ENPP1) was identified several decades ago as a type II transmembrane glycoprotein with nucleotide pyrophosphatase and phosphodiesterase enzymatic activities, critical for purinergic signaling. Recently, ENPP1 has emerged as a critical phosphodiesterase that degrades the stimulator of interferon genes (STING) ligand, cyclic GMP-AMP (cGAMP). cGAMP or analogs thereof have emerged as potent immunostimulatory agents, which have potential applications in immunotherapy. This emerging role of ENPP1 has placed this "old" enzyme at the frontier of immunotherapy. This review highlights the roles played by ENPP1, the mechanism of cGAMP hydrolysis by ENPP1, and small molecule inhibitors of ENPP1 with potential applications in diverse disease states, including cancer.
Topics: Animals; Drug Discovery; Gene Expression Regulation; Humans; Hydrolysis; Membrane Proteins; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Protein Binding; Pyrophosphatases; Signal Transduction; Structure-Activity Relationship
PubMed: 31752288
DOI: 10.3390/molecules24224192