scholarly journals Association of Mutations Identified in Xanthinuria with the Function and Inhibition Mechanism of Xanthine Oxidoreductase

Biomedicines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1723
Author(s):  
Mai Sekine ◽  
Ken Okamoto ◽  
Kimiyoshi Ichida
Keyword(s):  
Uric Acid ◽  
Complex Structure ◽  
Metabolic Effects ◽  
Inhibition Mechanism ◽  
Clinical Aspects ◽  
Type I ◽  
Xanthine Oxidoreductase ◽  
Enzymatic Function ◽  
Clinically Significant

Xanthine oxidoreductase (XOR) is an enzyme that catalyzes the two-step reaction from hypoxanthine to xanthine and from xanthine to uric acid in purine metabolism. XOR generally carries dehydrogenase activity (XDH) but is converted into an oxidase (XO) under various pathophysiologic conditions. The complex structure and enzymatic function of XOR have been well investigated by mutagenesis studies of mammalian XOR and structural analysis of XOR–inhibitor interactions. Three XOR inhibitors are currently used as hyperuricemia and gout therapeutics but are also expected to have potential effects other than uric acid reduction, such as suppressing XO–generating reactive oxygen species. Isolated XOR deficiency, xanthinuria type I, is a good model of the metabolic effects of XOR inhibitors. It is characterized by hypouricemia, markedly decreased uric acid excretion, and increased serum and urinary xanthine concentrations, with no clinically significant symptoms. The pathogenesis and relationship between mutations and XOR activity in xanthinuria are useful for elucidating the biological role of XOR and the details of the XOR reaction process. In this review, we aim to contribute to the basic science and clinical aspects of XOR by linking the mutations in xanthinuria to structural studies, in order to understand the function and reaction mechanism of XOR in vivo.

scholarly journals Functional redundancy of type I and type II receptors in the regulation of skeletal muscle growth by myostatin and activin A

2020 ◽  
Vol 117 (49) ◽  
pp. 30907-30917 ◽  
Author(s):  
Se-Jin Lee ◽  
Adam Lehar ◽  
Yewei Liu ◽  
Chi Hai Ly ◽  
Quynh-Mai Pham ◽  
...  
Keyword(s):  
Family Member ◽  
Muscle Mass ◽  
Transforming Growth Factor ◽  
Muscle Growth ◽  
Functional Redundancy ◽  
Activin A ◽  
Metabolic Effects ◽  
Type I ◽  
Type Ii

Myostatin (MSTN) is a transforming growth factor-β (TGF-β) family member that normally acts to limit muscle growth. The function of MSTN is partially redundant with that of another TGF-β family member, activin A. MSTN and activin A are capable of signaling through a complex of type II and type I receptors. Here, we investigated the roles of two type II receptors (ACVR2 and ACVR2B) and two type I receptors (ALK4 and ALK5) in the regulation of muscle mass by these ligands by genetically targeting these receptors either alone or in combination specifically in myofibers in mice. We show that targeting signaling in myofibers is sufficient to cause significant increases in muscle mass, showing that myofibers are the direct target for signaling by these ligands in the regulation of muscle growth. Moreover, we show that there is functional redundancy between the two type II receptors as well as between the two type I receptors and that all four type II/type I receptor combinations are utilized in vivo. Targeting signaling specifically in myofibers also led to reductions in overall body fat content and improved glucose metabolism in mice fed either regular chow or a high-fat diet, demonstrating that these metabolic effects are the result of enhanced muscling. We observed no effect, however, on either bone density or muscle regeneration in mice in which signaling was targeted in myofibers. The latter finding implies that MSTN likely signals to other cells, such as satellite cells, in addition to myofibers to regulate muscle homeostasis.

scholarly journals Crosstalk between invadopodia and the extracellular matrix

2020 ◽  
Author(s):  
Shinji Iizuka ◽  
Ronald P. Leon ◽  
Kyle P. Gribbin ◽  
Ying Zhang ◽  
Jose Navarro ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Type I Collagen ◽  
Complex Structure ◽  
Three Dimensional ◽  
3D Culture ◽  
Model Systems ◽  
Type I ◽  
Extracellular Matrix Components

ABSTRACTThe scaffold protein Tks5α is required for invadopodia-mediated cancer invasion both in vitro and in vivo. We have previously also revealed a role for Tks5 in tumor cell growth using three-dimensional (3D) culture model systems and mouse transplantation experiments. Here we use both 3D and high-density fibrillar collagen (HDFC) culture to demonstrate that native type I collagen, but not a form lacking the telopeptides, stimulated Tks5-dependent growth, which was dependent on the DDR collagen receptors. We used microenvironmental microarray (MEMA) technology to determine that laminin, collagen I, fibronectin and tropoelastin also stimulated invadopodia formation. A Tks5α-specific monoclonal antibody revealed its expression both on microtubules and at invadopodia. High- and super-resolution microscopy of cells in and on collagen was then used to place Tks5α at the base of invadopodia, separated from much of the actin and cortactin, but coincident with both matrix metalloprotease and cathepsin proteolytic activity. Inhibition of the Src family kinases, cathepsins or metalloproteases all reduced invadopodia length but each had distinct effects on Tks5α localization. These studies highlight the crosstalk between invadopodia and extracellular matrix components, and reveal the invadopodium to be a spatially complex structure.

scholarly journals The uric acid crystal receptor Clec12A potentiates type I interferon responses

2019 ◽  
Vol 116 (37) ◽  
pp. 18544-18549 ◽  
Author(s):  
Kai Li ◽  
Konstantin Neumann ◽  
Vikas Duhan ◽  
Sukumar Namineni ◽  
Anne Louise Hansen ◽  
...  
Keyword(s):  
Uric Acid ◽  
Myeloid Cell ◽  
Lymphocytic Choriomeningitis ◽  
Host Cells ◽  
Type I ◽  
Lectin Receptor ◽  
Molecular Patterns ◽  
Interferon Responses

The detection of microbes and damaged host cells by the innate immune system is essential for host defense against infection and tissue homeostasis. However, how distinct positive and negative regulatory signals from immune receptors are integrated to tailor specific responses in complex scenarios remains largely undefined. Clec12A is a myeloid cell-expressed inhibitory C-type lectin receptor that can sense cell death under sterile conditions. Clec12A detects uric acid crystals and limits proinflammatory pathways by counteracting the cell-activating spleen tyrosine kinase (Syk). Here, we surprisingly find that Clec12A additionally amplifies type I IFN (IFN-I) responses in vivo and in vitro. Using retinoic acid-inducible gene I (RIG-I) signaling as a model, we demonstrate that monosodium urate (MSU) crystal sensing by Clec12A enhances cytosolic RNA-induced IFN-I production and the subsequent induction of IFN-I–stimulated genes. Mechanistically, Clec12A engages Src kinase to positively regulate the TBK1-IRF3 signaling module. Consistently, Clec12A-deficient mice exhibit reduced IFN-I responses upon lymphocytic choriomeningitis virus (LCMV) infection, which affects the outcomes of these animals in acute and chronic virus infection models. Thus, our results uncover a previously unrecognized connection between an MSU crystal-sensing receptor and the IFN-I response, and they illustrate how the sensing of extracellular damage-associated molecular patterns (DAMPs) can shape the immune response.

SAC3B is a target of CML19, the centrin 2 of Arabidopsis thaliana

2020 ◽  
Vol 477 (1) ◽  
pp. 173-189 ◽  
Author(s):  
Marco Pedretti ◽  
Carolina Conter ◽  
Paola Dominici ◽  
Alessandra Astegno
Keyword(s):  
Excision Repair ◽  
Complex Structure ◽  
Binding Motif ◽  
C Terminus ◽  
Repair Protein ◽  
Nucleotide Excision ◽  
Ef Hand ◽  
Molecular Determinants ◽  
Structure In Solution

Arabidopsis centrin 2, also known as calmodulin-like protein 19 (CML19), is a member of the EF-hand superfamily of calcium (Ca2+)-binding proteins. In addition to the notion that CML19 interacts with the nucleotide excision repair protein RAD4, CML19 was suggested to be a component of the transcription export complex 2 (TREX-2) by interacting with SAC3B. However, the molecular determinants of this interaction have remained largely unknown. Herein, we identified a CML19-binding site within the C-terminus of SAC3B and characterized the binding properties of the corresponding 26-residue peptide (SAC3Bp), which exhibits the hydrophobic triad centrin-binding motif in a reversed orientation (I8W4W1). Using a combination of spectroscopic and calorimetric experiments, we shed light on the SAC3Bp–CML19 complex structure in solution. We demonstrated that the peptide interacts not only with Ca2+-saturated CML19, but also with apo-CML19 to form a protein–peptide complex with a 1 : 1 stoichiometry. Both interactions involve hydrophobic and electrostatic contributions and include the burial of Trp residues of SAC3Bp. However, the peptide likely assumes different conformations upon binding to apo-CML19 or Ca2+-CML19. Importantly, the peptide dramatically increases the affinity for Ca2+ of CML19, especially of the C-lobe, suggesting that in vivo the protein would be Ca2+-saturated and bound to SAC3B even at resting Ca2+-levels. Our results, providing direct evidence that Arabidopsis SAC3B is a CML19 target and proposing that CML19 can bind to SAC3B through its C-lobe independent of a Ca2+ stimulus, support a functional role for these proteins in TREX-2 complex and mRNA export.

Ridogrel Inhibits Systemic and Renal Formation of Thromboxane A2 and Antagonizes Platelet Thromboxane A2/Prostaglandin Endoperoxide Receptors upon Chronic Administration to Man

1992 ◽  
Vol 68 (02) ◽  
pp. 214-220 ◽  
Author(s):  
C Weber ◽  
J R Beetens ◽  
F Tegtmeier ◽  
P Van Rooy ◽  
E Vercammen ◽  
...  
Keyword(s):  
Uric Acid ◽  
Potent Inhibitor ◽  
Ex Vivo ◽  
Thromboxane A2 ◽  
Chronic Administration ◽  
Response Curves ◽  
Clinically Significant ◽  
Synthase Inhibitor ◽  
The Right ◽  
Steady State Plasma Level

SummaryThe effects of ridogrel, a dual thromboxane A2 (TXA2) synthase inhibitor and TXA2/prostaglandin (PG) endoperoxide receptor antagonist, on systemic and renal production of prostaglandins and on platelet TXA2/PG endoperoxide receptors was evaluated upon chronic administration (300 mg b. i. d. orally, for 8 and 29 days) to man. Such a medication with ridogrel inhibits the systemic as well as the renal production of TXA2 as measured by the urinary excretion of 2,3-dinor-TXB2 and TXB2 respectively without inducing significant changes in systemic or renal PGI2 production. Simultaneously with the latter effects, the production of TXB2 by spontaneously coagulated whole blood ex vivo is inhibited (>99%) while that of PGE2 and PGF2α is largely increased. Administration of ridogrel causes a three- to five-fold shift to the right of concentration-response curves for U46619 in eliciting platelet aggregation; no tachyphylaxis is observed after 29 days of treatment in this respect. Apart from a reduction of serum uric acid levels with a concomitant increase in urinary uric acid excretion during the first days of treatment, no clinically significant changes in hematological, biochemical, hemodynamic and coagulation parameters occur during the 8 days or 29 days study. The study demonstrates that ridogrel is a potent inhibitor of the systemic as well as renal TXA2 synthase and an antagonist of platelet TXA2/PG endoperoxide receptor in man, covering full activity during 24 h at steady-state plasma level conditions without tachyphylaxis during 29 days of medication. The compound is well tolerated, at least during 1 month of administration.

Peculiarities of the course of type I allergic reactions in patients with blood diseases

2020 ◽  
pp. 40-50
Author(s):  
A. Nikitina
Keyword(s):  
Search Engines ◽  
Anaphylactic Shock ◽  
Type I ◽  
Allergic Reactions ◽  
Common Cause ◽  
Blood Diseases ◽  
Treatment Regimens ◽  
Modern Methods

Analysis of literature data presented in search engines — Elibrary, PubMed, Cochrane — concerning the risk of developing type I allergic reactions in patients with blood diseases is presented. It is shown that the most common cause of type I allergic reactions is drugs included in the treatment regimens of this category of patients. The article presents statistics on the increase in the number of drug allergies leading to cases of anaphylactic shock in patients with blood diseases. Modern methods for the diagnosis of type I allergic reactions in vivo and in vitro are considered.

Collagen-the Ultrastructural Element of the Bone Matrix

2018 ◽  
Vol 69 (7) ◽  
pp. 1706-1709
Author(s):  
Nicoleta Dumitru ◽  
Andra Cocolos ◽  
Andra Caragheorgheopol ◽  
Constantin Dumitrache ◽  
Ovidiu Gabriel Bratu ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Bone Microarchitecture ◽  
Complex Structure ◽  
Bone Matrix ◽  
Organic Matrix ◽  
Bone Diseases ◽  
Bone Collagen ◽  
Type I ◽  
New Therapeutic Approaches ◽  
And Function

There is an increased interest and more studies highlight the fact that bone strength depends not only on bone tissue quantity, but also on its quality, which is characterized by the geometry and shape of bones, trabecular bone microarchitecture, mineral content, organic matrix and bone turnover. Fibrillar type I collagen is the major organic component of bone matrix, providing form and a stable template for mineralization. The biomedical importance of collagen as a biomaterial for medical and cosmetic purposes and the improvement of the molecular, cellular biology and analytical technologies, led to increasing interest in establishing the structure of this protein and in setting of the relationships between sequence, structure, and function. Bone collagen crosslinking chemistry and its molecular packing structure are considered to be distinct features. This unique post-translational modifications provide to the fibrillar collagen matrices properties such as tensile strength and viscoelasticity. Understanding the complex structure of bone type I collagen as well as the dynamic nature of bone tissues will help to manage new therapeutic approaches to bone diseases.

scholarly journals Enterococcus faecalis exploits the human fibrinolytic system to drive excess collagenolysis: implications in gut healing and identification of druggable targets

2020 ◽  
Vol 318 (1) ◽  
pp. G1-G9 ◽  
Author(s):  
Richard A. Jacobson ◽  
Kiedo Wienholts ◽  
Ashley J. Williamson ◽  
Sara Gaines ◽  
Sanjiv Hyoju ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Healing Process ◽  
Abdominal Sepsis ◽  
Infectious Complications ◽  
Fibrinolytic System ◽  
Clinical Safety ◽  
High Concentrations ◽  
Clinically Significant

Perforations, anastomotic leak, and subsequent intra-abdominal sepsis are among the most common and feared complications of invasive interventions in the colon and remaining intestinal tract. During physiological healing, tissue protease activity is finely orchestrated to maintain the strength and integrity of the submucosa collagen layer in the wound. We (Shogan, BD et al. Sci Trans Med 7: 286ra68, 2015.) have previously demonstrated in both mice and humans that the commensal microbe Enterococcus faecalis selectively colonizes wounded colonic tissues and disrupts the healing process by amplifying collagenolytic matrix-metalloprotease activity toward excessive degradation. Here, we demonstrate for the first time, to our knowledge, a novel collagenolytic virulence mechanism by which E. faecalis is able to bind and locally activate the human fibrinolytic protease plasminogen (PLG), a protein present in high concentrations in healing colonic tissue. E. faecalis-mediated PLG activation leads to supraphysiological collagen degradation; in this study, we demonstrate this concept both in vitro and in vivo. This pathoadaptive response can be mitigated with the PLG inhibitor tranexamic acid (TXA) in a fashion that prevents clinically significant complications in validated murine models of both E. faecalis- and Pseudomonas aeruginosa-mediated colonic perforation. TXA has a proven clinical safety record and is Food and Drug Administration approved for topical application in invasive procedures, albeit for the prevention of bleeding rather than infection. As such, the novel pharmacological effect described in this study may be translatable to clinical trials for the prevention of infectious complications in colonic healing. NEW & NOTEWORTHY This paper presents a novel mechanism for virulence in a commensal gut microbe that exploits the human fibrinolytic system and its principle protease, plasminogen. This mechanism is targetable by safe and effective nonantibiotic small molecules for the prevention of infectious complications in the healing gut.

scholarly journals Collagen-Based Electrospun Materials for Tissue Engineering: A Systematic Review

2021 ◽  
Vol 8 (3) ◽  
pp. 39
Author(s):  
Britani N. Blackstone ◽  
Summer C. Gallentine ◽  
Heather M. Powell
Keyword(s):  
Systematic Review ◽  
Tissue Engineering ◽  
Collagen Type I ◽  
The Body ◽  
Pool Data ◽  
Type I ◽  
High Concentrations ◽  
Increased Strength

Collagen is a key component of the extracellular matrix (ECM) in organs and tissues throughout the body and is used for many tissue engineering applications. Electrospinning of collagen can produce scaffolds in a wide variety of shapes, fiber diameters and porosities to match that of the native ECM. This systematic review aims to pool data from available manuscripts on electrospun collagen and tissue engineering to provide insight into the connection between source material, solvent, crosslinking method and functional outcomes. D-banding was most often observed in electrospun collagen formed using collagen type I isolated from calfskin, often isolated within the laboratory, with short solution solubilization times. All physical and chemical methods of crosslinking utilized imparted resistance to degradation and increased strength. Cytotoxicity was observed at high concentrations of crosslinking agents and when abbreviated rinsing protocols were utilized. Collagen and collagen-based scaffolds were capable of forming engineered tissues in vitro and in vivo with high similarity to the native structures.

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