scholarly journals Macrothrombocytopenia of Takenouchi-Kosaki syndrome is ameliorated by CDC42 specific- and lipidation inhibitors in MEG-01 cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Etsuko Daimon ◽  
Yukinao Shibukawa ◽  
Suganya Thanasegaran ◽  
Natsuko Yamazaki ◽  
Nobuhiko Okamoto
Keyword(s):  
Clinical Manifestations ◽  
Hek293 Cells ◽  
Actin Dynamics ◽  
Missense Mutations ◽  
Wild Type ◽  
Pharmacological Treatments ◽  
Platelet Production ◽  
Chemical Inhibitors ◽  
Membrane Compartment ◽  
Impaired Binding

AbstractMacrothrombocytopenia is a common pathology of missense mutations in genes regulating actin dynamics. Takenouchi-Kosaki syndrome (TKS) harboring the c.191A > G, Tyr64Cys (Y64C) variant in Cdc42 exhibits a variety of clinical manifestations, including immunological and hematological anomalies. In the present study, we investigated the functional abnormalities of the Y64C mutant in HEK293 cells and elucidated the mechanism of macrothrombocytopenia, one of the symptoms of TKS patients, by monitoring the production of platelet-like particles (PLP) using MEG-01 cells. We found that the Y64C mutant was concentrated at the membrane compartment due to impaired binding to Rho-GDI and more active than the wild-type. The Y64C mutant also had lower association with its effectors Pak1/2 and N-WASP. Y64C mutant-expressing MEG-01 cells demonstrated short cytoplasmic protrusions with aberrant F-actin and microtubules, and reduced PLP production. This suggested that the Y64C mutant facilitates its activity and membrane localization, resulting in impaired F-actin dynamics for proplatelet extension, which is necessary for platelet production. Furthermore, such dysfunction was ameliorated by either suppression of Cdc42 activity or prenylation using chemical inhibitors. Our study may lead to pharmacological treatments for TKS patients.

scholarly journals Missense Mutations in the Melanocortin 2 Receptor Accessory Protein That Lead to Late Onset Familial Glucocorticoid Deficiency Type 2

2010 ◽  
Vol 31 (3) ◽  
pp. 396-397
Author(s):  
C. R. Hughes ◽  
T. T. Chung ◽  
A. M. Habeb ◽  
F. Kelestimur ◽  
A. J. L. Clark ◽  
...  
Keyword(s):  
Dose Response ◽  
Late Onset ◽  
Hek293 Cells ◽  
Accessory Protein ◽  
Missense Mutations ◽  
Wild Type ◽  
Response Curves ◽  
Patient Reported ◽  
Glucocorticoid Deficiency

ABSTRACT Background Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder characterized by isolated glucocorticoid deficiency. Mutations in the ACTH receptor [melanocortin 2 receptor (MC2R)] or the MC2R accessory protein (MRAP) cause FGD types 1 and 2, respectively. Typically, type 2 patients present early (median age, 0.1 yr), and no patient reported to date has presented after 1.6 yr. Aim The aim of this study was to investigate the cause of disease in two families with late-onset FGD. Patients The proband in family 1 was diagnosed at age 4 yr. Family review revealed two older siblings with undiagnosed FGD. One sibling was well, whereas the second had cerebral palsy secondary to hypoglycemic seizures. The proband in family 2 was diagnosed at age 18 yr with symptoms of fatigue, weight loss, and depression. Methods The coding exons of MC2R and MRAP were sequenced. ACTH dose-response curves were generated for MC2R when transfected with wild-type or mutant MRAP constructs using HEK293 cells. MC2R trafficking with both mutant MRAPs was investigated using immunocytochemistry. Results MRAP gene analysis identified two novel homozygous missense mutations, c.175T>G (pY59D) in family 1 and c.76T>C (p.V26A) in family 2. In vitro analysis showed that the Y59D mutant had significant impairment of cAMP generation, and both mutants caused a shift in the dose-response curve to the right when compared to wild type. Immunocytochemistry showed normal trafficking of MC2R when transfected with both mutant MRAPs, indicating a probable signaling defect. Conclusion These results indicate that missense MRAP mutations present with a variable phenotype of ACTH resistance and can present late in life.

Compound heterozygosity for mutations Asp611→Tyr in KCNQ1 and Asp609→Gly in KCNH2 associated with severe long QT syndrome

2005 ◽  
Vol 108 (2) ◽  
pp. 143-150 ◽  
Author(s):  
Masato YAMAGUCHI ◽  
Masami SHIMIZU ◽  
Hidekazu INO ◽  
Hidenobu TERAI ◽  
Kenshi HAYASHI ◽  
...  
Keyword(s):  
Long Qt Syndrome ◽  
Clinical Manifestations ◽  
Torsades De Pointes ◽  
Dominant Negative ◽  
Missense Mutations ◽  
Wild Type ◽  
Long Qt ◽  
Mild Phenotype ◽  
Electrophysiological Properties ◽  
Qt Syndrome

LQTS (long QT syndrome) is an inherited cardiac disorder characterized by prolongation of QT interval, torsades de pointes and sudden death. We have identified two heterozygous missense mutations in the KCNQ1 and KCNH2 (also known as HERG) genes [Asp611→Tyr (D611Y) in KCNQ1 and Asp609→Gly (D609G) in KCNH2] in a 2-year-old boy with LQTS. The aim of the present study was to characterize the contributions of the mutations in the KCNQ1 and KCNH2 genes relative to the clinical manifestations and electrophysiological properties of LQTS. Six of 11 carriers of D611Y in KCNQ1 had long QT intervals. D609G in KCNH2 was detected only in the proband. Studies on the electrophysiological alterations due to the two missense mutations revealed that the D611Y mutation in KCNQ1 did not show a significant suppression of the currents compared with wild-type, but the time constants of current activation in the mutants were increased compared with that in the wild-type. In contrast, the D609G mutation in KCNH2 showed a dominant-negative suppression. Our results suggest that the mild phenotype produced by the D611Y mutation in KCNQ1 became more serious by addition of the D609G mutation in KCNH2 in the proband.

Platelet Activation and Aggregation Induced by Recombinant von Willebrand Factors Reproducing Four Type 2B von Willebrand Disease Missense Mutations

1998 ◽  
Vol 79 (01) ◽  
pp. 211-216 ◽  
Author(s):  
Lysiane Hilbert ◽  
Claudine Mazurier ◽  
Christophe de Romeuf
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Von Willebrand Disease ◽  
Platelet Glycoprotein ◽  
Missense Mutations ◽  
Inhibit Platelet Aggregation ◽  
Wild Type ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryType 2B of von Willebrand disease (vWD) refers to qualitative variants with increased affinity of von Willebrand factor (vWF) for platelet glycoprotein Ib (GPIb). All the mutations responsible for type 2B vWD have been located in the A1 domain of vWF. In this study, various recombinant von Willebrand factors (rvWF) reproducing four type 2B vWD missense mutations were compared to wild-type rvWF (WT-rvWF) for their spontaneous binding to platelets and their capacity to induce platelet activation and aggregation. Our data show that the multimeric pattern of each mutated rvWF is similar to that of WT-rvWF but the extent of spontaneous binding and the capacity to induce platelet activation and aggregation are more important for the R543Q and V553M mutations than for the L697V and A698V mutations. Both the binding of mutated rvWFs to platelets and platelet aggregation induced by type 2B rvWFs are inhibited by monoclonal anti-GPIb and anti-vWF antibodies, inhibitors of vWF binding to platelets in the presence of ristocetin, as well as by aurin tricarboxylic acid. On the other hand, EDTA and a monoclonal antibody directed against GPIIb/IIIa only inhibit platelet aggregation. Furthermore, the incubation of type 2B rvWFs with platelets, under stirring conditions, results in the decrease in high molecular weight vWF multimers in solution, the extent of which appears correlated with that of plasma vWF from type 2B vWD patients harboring the corresponding missense mutation. This study supports that the binding of different mutated type 2B vWFs onto platelet GPIb induces various degrees of platelet activation and aggregation and thus suggests that the phenotypic heterogeneity of type 2B vWD may be related to the nature and/or location of the causative point mutation.

scholarly journals Structural and Thermodynamic Analysis of the Resistance Development to Pimodivir (VX-787), the Clinical Inhibitor of Cap Binding to PB2 Subunit of Influenza A Polymerase

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1007
Author(s):  
Jiří Gregor ◽  
Kateřina Radilová ◽  
Jiří Brynda ◽  
Jindřich Fanfrlík ◽  
Jan Konvalinka ◽  
...  
Keyword(s):  
Thermodynamic Analysis ◽  
Influenza A ◽  
Polymerase Activity ◽  
Second Phase ◽  
Missense Mutations ◽  
Wild Type ◽  
Resistance Development ◽  
Third Phase ◽  
Major Mutation ◽  
Control And Prevention

Influenza A virus (IAV) encodes a polymerase composed of three subunits: PA, with endonuclease activity, PB1 with polymerase activity and PB2 with host RNA five-prime cap binding site. Their cooperation and stepwise activation include a process called cap-snatching, which is a crucial step in the IAV life cycle. Reproduction of IAV can be blocked by disrupting the interaction between the PB2 domain and the five-prime cap. An inhibitor of this interaction called pimodivir (VX-787) recently entered the third phase of clinical trial; however, several mutations in PB2 that cause resistance to pimodivir were observed. First major mutation, F404Y, causing resistance was identified during preclinical testing, next the mutation M431I was identified in patients during the second phase of clinical trials. The mutation H357N was identified during testing of IAV strains at Centers for Disease Control and Prevention. We set out to provide a structural and thermodynamic analysis of the interactions between cap-binding domain of PB2 wild-type and PB2 variants bearing these mutations and pimodivir. Here we present four crystal structures of PB2-WT, PB2-F404Y, PB2-M431I and PB2-H357N in complex with pimodivir. We have thermodynamically analysed all PB2 variants and proposed the effect of these mutations on thermodynamic parameters of these interactions and pimodivir resistance development. These data will contribute to understanding the effect of these missense mutations to the resistance development and help to design next generation inhibitors.

scholarly journals Investigation of the Stability of Yeast rad52 Mutant Proteins Uncovers Post-translational and Transcriptional Regulation of Rad52p

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 91-101 ◽  
Author(s):  
Erin N Asleson ◽  
Dennis M Livingston
Keyword(s):  
Half Life ◽  
Translational Regulation ◽  
Cellular Level ◽  
Missense Mutations ◽  
Wild Type ◽  
Mutant Proteins ◽  
Gal1 Promoter ◽  
Rad52 Protein ◽  
The Stability ◽  
Mutant Forms

Abstract We investigated the stability of the Saccharomyces cerevisiae Rad52 protein to learn how a cell controls its quantity and longevity. We measured the cellular levels of wild-type and mutant forms of Rad52p when expressed from the RAD52 promoter and the half-lives of the various forms of Rad52p when expressed from the GAL1 promoter. The wild-type protein has a half-life of 15 min. rad52 mutations variably affect the cellular levels of the protein products, and these levels correlate with the measured half-lives. While missense mutations in the N terminus of the protein drastically reduce the cellular levels of the mutant proteins, two mutations—one a deletion of amino acids 210-327 and the other a missense mutation of residue 235—increase the cellular level and half-life more than twofold. These results suggest that Rad52p is subject to post-translational regulation. Proteasomal mutations have no effect on Rad52p half-life but increase the amount of RAD52 message. In contrast to Rad52p, the half-life of Rad51p is >2 hr, and RAD51 expression is unaffected by proteasomal mutations. These differences between Rad52p and Rad51p suggest differential regulation of two proteins that interact in recombinational repair.

scholarly journals Clinical Manifestations of Hemochromatosis inHFEC282Y Homozygotes Identified by Screening

2008 ◽  
Vol 22 (11) ◽  
pp. 923-930 ◽  
Author(s):  
Gordon D McLaren ◽  
Christine E McLaren ◽  
Paul C Adams ◽  
James C Barton ◽  
David M Reboussin ◽  
...  
Keyword(s):  
Iron Overload ◽  
Serum Ferritin ◽  
Elevated Serum ◽  
Clinical Signs ◽  
Clinical Manifestations ◽  
Joint Stiffness ◽  
Chronic Fatigue ◽  
Newly Diagnosed ◽  
Wild Type ◽  
Control Subjects

BACKGROUND: Patients with hemochromatosis may suffer organ damage from iron overload, often with serious clinical consequences.OBJECTIVE: To assess prevalences of self-reported symptoms and clinical signs and conditions in persons homozygous for the hemochromatosis gene (HFE)mutation (C282Y) identified by screening.METHODS: Participants were adults 25 years of age or older enrolled in the Hemochromatosis and Iron Overload Screening (HEIRS) Study. C282Y homozygotes (n=282) were compared with control participants without theHFEC282Y or H63D alleles (ie, wild type/wild type; n=364).RESULTS: Previously diagnosed C282Y homozygotes and newly diagnosed homozygotes with elevated serum ferritin levels had higher prevalences of certain symptoms such as chronic fatigue (OR 2.8; 95% CI 1.34 to 5.95, and OR 2.0; 95% CI 1.07 to 3.75, respectively), and had more hyperpigmentation on physical examination (OR 4.7; 95% CI 1.50 to 15.06, and OR 3.7; 95% CI 1.10 to 12.16, respectively) and swelling or tenderness of the second and third metacarpophalangeal joints (OR 4.2; 95% CI 1.37 to 13.03, and OR 3.3; 95% CI 1.17 to 9.49, respectively) than control subjects. Joint stiffness was also more common among newly diagnosed C282Y homozygotes with elevated serum ferritin than among control subjects (OR 2.7; 95% CI 1.38 to 5.30). However, the sex- and age-adjusted prevalences of self-reported symptoms and signs of liver disease, heart disease, diabetes and most other major clinical manifestations of hemochromatosis were similar in C282Y homozygotes and control subjects.CONCLUSIONS: Some symptoms and conditions associated with hemochromatosis were more prevalent among C282Y homozygotes identified by screening than among control subjects, but prevalences of most outcomes were similar in C282Y homozygotes and controls in this primary care-based study.

Abstract P459: Mavacamten And Danicamtiv Reverse Respective Contractile Abnormalities In Engineered Heart Tissue Models Of Hypertrophic And Dilated Cardiomyopathy

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Saiti S Halder ◽  
Lorenzo R Sewanan ◽  
Michael J Rynkiewicz ◽  
Jeffrey R Moore ◽  
William J Lehman ◽  
...  
Keyword(s):  
Dilated Cardiomyopathy ◽  
Calcium Sensitivity ◽  
Heart Tissue ◽  
Missense Mutations ◽  
Wild Type ◽  
Twitch Force ◽  
In Vitro Motility ◽  
Isometric Twitch ◽  
Engineered Heart Tissues

Missense mutations in alpha-tropomyosin (TPM1) can lead to development of hypertrophic (HCM) or dilated cardiomyopathy (DCM). HCM mutation E62Q and DCM mutation E54K have previously been studied extensively in experimental systems ranging from in vitro biochemical assays to animal models, although some conflicting results have been found. We undertook a detailed multi-scale assessment of these mutants that included atomistic simulations, regulated in vitro motility (IVM) assays, and finally physiologically relevant human engineered heart tissues. In IVM assays, E62Q previously has shown increased Calcium sensitivity. New molecular dynamics data shows mutation-induced changes to tropomyosin dynamics and interactions with actin and troponin. Human engineered heart tissues (EHT) were generated by seeding iPSC-derived cardiomyocytes engineered using CRISPR/CAS9 to express either E62Q or E54K cardiomyopathy mutations. After two weeks in culture, E62Q EHTs showed a drastically hypercontractile twitch force and significantly increased stiffness while displaying little difference in twitch kinetics compared to wild-type isogenic control EHTs. On the other hand, E54K EHTs displayed hypocontractile isometric twitch force with faster kinetics, impaired length-dependent activation and lowered stiffness. Given these contractile abnormalities, we hypothesized that small molecule myosin modulators to appropriately activate or inhibit myosin activity would restore E54K or E62Q EHTs to normal behavior. Accordingly, E62Q EHTs were treated with 0.5μM mavacamten (to remedy hypercontractility) and E54K EHTs with 0.5 μM danicamtiv (to remedy hypocontractility) for 4 days, followed by a 1 day washout period. Upon contractility testing, it was observed that the drugs were able to reverse contractile phenotypes observed in mutant EHTs and restore contractile properties to levels resembling those of the untreated wild type group. The computational, IVM and EHT studies provide clear evidence in support of the hyper- vs. hypo-contractility paradigm as a common axis that distinguishes HCM and DCM TPM1 mutations. Myosin modulators that directly compensate for underlying myofilament aberrations show promising efficacy in human in vitro systems.

Abstract 14035: Renal Tubular Secretion and Cardiac Distribution of Dofetilide is Dependent on MATE1 Function

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Muhammad Erfan Uddin ◽  
Yan Jin ◽  
Alice A Gibson ◽  
Ingrid M Bonilla ◽  
Cynthia A Carnes ◽  
...  
Keyword(s):  
Organic Cation ◽  
Tubular Secretion ◽  
Hek293 Cells ◽  
Delayed Rectifier ◽  
Organic Cation Transporters ◽  
Wild Type ◽  
Renal Tubular Secretion ◽  
Cation Transporters ◽  
Renal Tubular

Introduction: Dofetilide is a delayed rectifier potassium channel inhibitor used to treat patients with atrial fibrillation and flutter, and its use is associated with a risk of QT prolongation and Torsades de Pointes . The mechanisms involved in dofetilide’s renal tubular secretion and its uptake into cardiomyocytes remain unknown. Previously reported drug-drug interaction (DDI) studies suggest the involvement of organic cation transporters. Here, we investigated the contribution of organic cation transporters (OCT2 and MATE1) to the pharmacokinetics of dofetilide to gain insight into its DDI potential. Hypothesis: Based on known DDIs with dofetilide, we hypothesize that OCT2 and/or MATE1 play a key role in the inter-individual variability in pharmacokinetics and pharmacodynamics of dofetilide. Methods: In vitro and ex vivo transport kinetics of dofetilide were determined in HEK293 cells stably transfected with OCT2 or MATE1, and in isolated cardiomyocytes, respectively. In vivo studies were performed in wild-type, OCT2-, and MATE1-deficient mice (n=5) receiving dofetilide (5 mg/kg, p.o., 2.5 mg/kg, i.v.), with or without several contraindicated drugs. Dofetilide concentrations in plasma and urine were determined by UPLC-MS/MS. Results: In vitro studies demonstrated that dofetilide is a good substrate of MATE1 but not OCT2. Deficiency of MATE1 was associated with increased plasma concentrations of dofetilide and with a significantly reduced urinary excretion (3-fold in females and 5-fold in males, respectively). Dofetilide accumulation in cardiomyocytes was increased by 2-fold in MATE1-deficient females, and pre-incubation with the MATE1 inhibitor cimetidine significantly reduced dofetilide uptake in wild-type cardiomyocytes. Several contraindicated drugs listed in the dofetilide prescribing information, including cimetidine, ketoconazole, increased dofetilide plasma exposure in wild-type mice by >2.8-fold. Conclusion: Renal secretion of dofetilide is mediated by MATE1 and is highly sensitive to inhibition by many widely used prescription drugs that can cause clinically relevant DDIs. Deficiency of MATE1 also increases accumulation in the heart which may contribute to individual variation in response to dofetilide.

scholarly journals Molecular detection and phylogenetic relationship of wild-type strains of canine distemper virus in symptomatic dogs from Uberlândia, Minas Gerais

2015 ◽  
Vol 67 (6) ◽  
pp. 1510-1518
Author(s):  
S.A. Headley ◽  
T.R. Santos ◽  
L. Bodnar ◽  
J.P.E. Saut ◽  
A.P. Silva ◽  
...  
Keyword(s):  
Canine Distemper Virus ◽  
Phylogenetic Analyses ◽  
Clinical Manifestations ◽  
N Gene ◽  
Clinical Samples ◽  
Canine Distemper ◽  
Wild Type ◽  
Age Related ◽  
Relationship Of ◽  
Type Strains

This study investigated the occurrence of canine distemper virus (CDV) by evaluating the presence of viral RNA within urine samples of dogs from Uberlândia, MG, with clinical manifestations suggestive of infection by CDV by targeting the CDV N gene. Of the clinical samples collected ( n =33), CDV viruria was detected in 45.5%. Five dogs died spontaneously; all had characteristic CDV-associated histopathological alterations and demonstrated CDV viruria. Statistical analyses revealed that the age, gender, breed, or the organ system of the dog affected had no influence on the occurrence of canine distemper. Myoclonus and motor incoordination were the most significant neurological manifestations observed. A direct association was observed between keratoconjunctivitis and dogs with CDV viruria. These findings suggest that CDV viruria in symptomatic dogs might not be age related, and that symptomatic dogs can demonstrate clinical manifestations attributed to CDV without viruria identified by RT-PCR. Additionally, the results of the sequence identities analysed have suggested that all Brazilian wild-type strains of CDV currently identified are closely related and probably originated from the same lineage of CDV. Nevertheless, phylogenetic analyses suggest that there are different clusters of wild-type strains of CDV circulating within urban canine populations in Brazil.

scholarly journals Engineering selectivity into RGK GTPase inhibition of voltage-dependent calcium channels

2018 ◽  
Vol 115 (47) ◽  
pp. 12051-12056 ◽  
Author(s):  
Akil A. Puckerin ◽  
Donald D. Chang ◽  
Zunaira Shuja ◽  
Papiya Choudhury ◽  
Joachim Scholz ◽  
...  
Keyword(s):  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Hek293 Cells ◽  
Channel Blockers ◽  
Wild Type ◽  
Voltage Dependent ◽  
Somatosensory Neurons ◽  
Potential Applications ◽  
Voltage Dependent Calcium Channels ◽  
Potential Therapeutics

Genetically encoded inhibitors for voltage-dependent Ca2+ (CaV) channels (GECCIs) are useful research tools and potential therapeutics. Rad/Rem/Rem2/Gem (RGK) proteins are Ras-like G proteins that potently inhibit high voltage-activated (HVA) Ca2+ (CaV1/CaV2 family) channels, but their nonselectivity limits their potential applications. We hypothesized that nonselectivity of RGK inhibition derives from their binding to auxiliary CaVβ-subunits. To investigate latent CaVβ-independent components of inhibition, we coexpressed each RGK individually with CaV1 (CaV1.2/CaV1.3) or CaV2 (CaV2.1/CaV2.2) channels reconstituted in HEK293 cells with either wild-type (WT) β2a or a mutant version (β2a,TM) that does not bind RGKs. All four RGKs strongly inhibited CaV1/CaV2 channels reconstituted with WT β2a. By contrast, when channels were reconstituted with β2a,TM, Rem inhibited only CaV1.2, Rad selectively inhibited CaV1.2 and CaV2.2, while Gem and Rem2 were ineffective. We generated mutant RGKs (Rem[R200A/L227A] and Rad[R208A/L235A]) unable to bind WT CaVβ, as confirmed by fluorescence resonance energy transfer. Rem[R200A/L227A] selectively blocked reconstituted CaV1.2 while Rad[R208A/L235A] inhibited CaV1.2/CaV2.2 but not CaV1.3/CaV2.1. Rem[R200A/L227A] and Rad[R208A/L235A] both suppressed endogenous CaV1.2 channels in ventricular cardiomyocytes and selectively blocked 25 and 62%, respectively, of HVA currents in somatosensory neurons of the dorsal root ganglion, corresponding to their distinctive selectivity for CaV1.2 and CaV1.2/CaV2.2 channels. Thus, we have exploited latent β-binding–independent Rem and Rad inhibition of specific CaV1/CaV2 channels to develop selective GECCIs with properties unmatched by current small-molecule CaV channel blockers.

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