scholarly journals Characterization of the Endogenous DAF-12 Ligand and Its Use as an Anthelmintic Agent in Strongyloides stercoralis

2021 ◽  
Author(s):  
Zhu Wang ◽  
Mi Cheong Cheong ◽  
Jet Tsien ◽  
Heping Deng ◽  
Tian Qin ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Strongyloides Stercoralis ◽  
Preclinical Model ◽  
Loss Of Function ◽  
Drug Of Choice ◽  
Lethal Infection ◽  
Parasite Reproduction ◽  
Rate Limiting

ABSTRACTA prevalent feature of Strongyloides stercoralis is a life-long and potentially lethal infection that is due to the nematode parasite’s ability to autoinfect and, thereby, self-replicate within its host. Here, we investigated the role of the parasite’s nuclear receptor, Ss-DAF-12, in governing infection. We identified Δ7-DA as the endogenous Ss-DAF-12 ligand and elucidated the hormone’s biosynthetic pathway. Genetic loss of function of the ligand’s rate-limiting enzyme demonstrated that Δ7-DA synthesis is necessary for parasite reproduction, whereas its absence is required for development of infectious larvae. Availability of the ligand permits Ss-DAF-12 to function as an on/off switch governing autoinfection, making it vulnerable to therapeutic intervention. In a preclinical model of hyperinfection, pharmacologic activation of DAF-12 suppressed autoinfection and markedly reduced lethality. Moreover, when Δ7-DA was administered with ivermectin, the current but limited drug of choice for treating strongyloidiasis, the combinatorial effects of the two drugs resulted in a near cure of the disease.

scholarly journals Characterization of the endogenous DAF-12 ligand and its use as an anthelmintic agent in Strongyloides stercoralis

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Zhu Wang ◽  
Mi Cheong Cheong ◽  
Jet Tsien ◽  
Heping Deng ◽  
Tian Qin ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Strongyloides Stercoralis ◽  
Preclinical Model ◽  
Loss Of Function ◽  
Drug Of Choice ◽  
Lethal Infection ◽  
Parasite Reproduction ◽  
Rate Limiting

A prevalent feature of Strongyloides stercoralis is a life-long and potentially lethal infection that is due to the nematode parasite’s ability to autoinfect and, thereby, self-replicate within its host. Here, we investigated the role of the parasite’s nuclear receptor, Ss-DAF-12, in governing infection. We identified Δ7-DA as the endogenous Ss-DAF-12 ligand and elucidated the hormone’s biosynthetic pathway. Genetic loss of function of the ligand’s rate-limiting enzyme demonstrated that Δ7-DA synthesis is necessary for parasite reproduction, whereas its absence is required for the development of infectious larvae. Availability of the ligand permits Ss-DAF-12 to function as an on/off switch governing autoinfection, making it vulnerable to therapeutic intervention. In a preclinical model of hyperinfection, pharmacologic activation of DAF-12 suppressed autoinfection and markedly reduced lethality. Moreover, when Δ7-DA was administered with ivermectin, the current but limited drug of choice for treating strongyloidiasis, the combinatorial effects of the two drugs resulted in a near cure of the disease.

scholarly journals Expression, Purification, and Characterization of (R)-Sulfolactate Dehydrogenase (ComC) from the Rumen MethanogenMethanobrevibacter milleraeSM9

Archaea ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-6
Author(s):  
Yanli Zhang ◽  
Linley R. Schofield ◽  
Carrie Sang ◽  
Debjit Dey ◽  
Ron S. Ronimus
Keyword(s):  
Biosynthetic Pathway ◽  
Critical Role ◽  
Reduction Reaction ◽  
Coenzyme M ◽  
Purification And Characterization ◽  
The Third ◽  
Optimal Activity ◽  
Methyl Coenzyme M Reductase

(R)-Sulfolactate dehydrogenase (EC 1.1.1.337), termed ComC, is a member of an NADH/NADPH-dependent oxidoreductase family of enzymes that catalyze the interconversion of 2-hydroxyacids into their corresponding 2-oxoacids. The ComC reaction is reversible and in the biosynthetic direction causes the conversion of (R)-sulfolactate to sulfopyruvate in the production of coenzyme M (2-mercaptoethanesulfonic acid). Coenzyme M is an essential cofactor required for the production of methane by the methyl-coenzyme M reductase complex. ComC catalyzes the third step in the first established biosynthetic pathway of coenzyme M and is also involved in methanopterin biosynthesis. In this study, ComC fromMethanobrevibacter milleraeSM9 was cloned and expressed inEscherichia coliand biochemically characterized. Sulfopyruvate was the preferred substrate using the reduction reaction, with 31% activity seen for oxaloacetate and 0.2% seen forα-ketoglutarate. Optimal activity was observed at pH 6.5. The apparentKMfor coenzyme (NADH) was 55.1 μM, and for sulfopyruvate, it was 196 μM (for sulfopyruvate theVmaxwas 93.9 μmol min−1 mg−1andkcatwas 62.8 s−1). The critical role of ComC in two separate cofactor pathways makes this enzyme a potential means of developing methanogen-specific inhibitors for controlling ruminant methane emissions which are increasingly being recognized as contributing to climate change.

scholarly journals Genome-Wide Identification and Characterization of MLO Gene Family in Octoploid Strawberry (Fragaria ×ananassa)

2020 ◽  
Author(s):  
Ronald R. Tapia ◽  
Christopher R. Barbey ◽  
Saket Chandra ◽  
Kevin M. Folta ◽  
Vance M. Whitaker ◽  
...  
Keyword(s):  
Gene Family ◽  
Genomic Structure ◽  
Resistance Locus ◽  
Fragaria Ananassa ◽  
Loss Of Function ◽  
Genetic Studies ◽  
Genome Wide ◽  
Segregating Population

AbstractPowdery mildew (PM) caused by Podosphaera aphanis is a major fungal disease in cultivated strawberry. Mildew Resistance Locus O (MLO) is a gene family described for having conserved seven-transmembrane domains. Induced loss-of-function in specific MLO genes can confer durable and broad resistance against PM pathogens. However, the underlying biological role of MLO genes in strawberry is still unknown. In the present study, the genomic structure of MLO genes were characterized in both diploid (Fragaria vesca) and octoploid strawberry (Fragaria ×ananassa), and the potential sources of MLO-mediated susceptibility were identified. Twenty MLO-like sequences were identified in F. vesca, with sixty-eight in F. ×ananassa. Phylogenetic analysis divides strawberry MLO genes into eight different clades, in which three FveMLO and ten FaMLO genes were grouped together with the functionally known MLO susceptibility. Out of ten FaMLO genes, FaMLO17-2 and FaMLO17-3 showed the highest similarity to the known susceptibility MLO proteins. Gene expression analysis of FaMLO genes was conducted using a multi-parental segregating population. Three expression quantitative trait loci (eQTL) were substantially associated with MLO transcript levels in mature fruits, suggesting discrete genetic control of susceptibility. These results are a critical first step in understanding allele function of MLO genes, and are necessary for further genetic studies of PM resistance in cultivated strawberry.

Abstract 261: Robust Cardioprotection Afforded by a Previously Unrecognized Link between the Unfolded Protein Response and the Hexosamine Biosynthetic Pathway

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Zhao V Wang ◽  
Yingfeng Deng ◽  
Ningguo Gao ◽  
Zully Pedrozo ◽  
Dan Li ◽  
...  
Keyword(s):  
Unfolded Protein Response ◽  
Biosynthetic Pathway ◽  
Ischemia Reperfusion ◽  
Uridine Diphosphate ◽  
Hexosamine Biosynthetic Pathway ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Rate Limiting

Background: The hexosamine biosynthetic pathway (HBP) generates UDP-GlcNAc (uridine diphosphate N-acetylglucosamine) for glycan synthesis and O-linked GlcNAc (O-GlcNAc) protein modifications. Despite the established role of the HBP in glucose metabolism and multiple diseases, regulation of the HBP remains largely undefined. Methods & Results: Here, we show that spliced Xbp1 (Xbp1s), the most conserved signal transducer of the unfolded protein response (UPR), is a direct transcriptional activator of the HBP. We demonstrate that the UPR triggers activation of the HBP by means of Xbp1s-dependent transcription of genes coding for key, rate-limiting enzymes. We establish that this previously unrecognized UPR-HBP axis is triggered in a variety of stress conditions known to promote O-GlcNAc modification. We go on to demonstrate that Xbp1s, acutely stimulated by ischemia/reperfusion (I/R) in heart, confers robust cardioprotection against I/R injury. We also show that HBP induction is required for this cardioprotective response. Mechanistically, HBP may mediate the adaptive branch of the UPR by activating autophagy and ER-associated degradation. Conclusion: These studies reveal that Xbp1s couples the UPR to the HBP, promoting robust cardioprotection during I/R.

scholarly journals Human RIPK1 deficiency causes combined immunodeficiency and inflammatory bowel diseases

2018 ◽  
Vol 116 (3) ◽  
pp. 970-975 ◽  
Author(s):  
Yue Li ◽  
Marita Führer ◽  
Ehsan Bahrami ◽  
Piotr Socha ◽  
Maja Klaudel-Dreszler ◽  
...  
Keyword(s):  
Cell Death ◽  
Intestinal Inflammation ◽  
Intestinal Epithelial ◽  
Loss Of Function ◽  
Monogenic Disorders ◽  
Bowel Diseases ◽  
Inflammatory Bowel ◽  
Human Immune

Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) is a critical regulator of cell death and inflammation, but its relevance for human disease pathogenesis remains elusive. Studies of monogenic disorders might provide critical insights into disease mechanisms and therapeutic targeting of RIPK1 for common diseases. Here, we report on eight patients from six unrelated pedigrees with biallelic loss-of-function mutations in RIPK1 presenting with primary immunodeficiency and/or intestinal inflammation. Mutations in RIPK1 were associated with reduced NF-κB activity, defective differentiation of T and B cells, increased inflammasome activity, and impaired response to TNFR1-mediated cell death in intestinal epithelial cells. The characterization of RIPK1-deficient patients highlights the essential role of RIPK1 in controlling human immune and intestinal homeostasis, and might have critical implications for therapies targeting RIPK1.

scholarly journals Generation and Characterization of a CRISPR/Cas9-Mediated SNAP29 Knockout in Human Fibroblasts

2021 ◽  
Vol 22 (10) ◽  
pp. 5293
Author(s):  
Marie Christine Martens ◽  
Janin Edelkamp ◽  
Christina Seebode ◽  
Mirijam Schäfer ◽  
Susanne Stählke ◽  
...  
Keyword(s):  
Primary Cilia ◽  
Human Fibroblasts ◽  
Human Cell Line ◽  
Epidermal Differentiation ◽  
Loss Of Function ◽  
Lentiviral Transduction ◽  
Protein Receptor ◽  
Models Comparison

Loss-of-function mutations in the synaptosomal-associated protein 29 (SNAP29) lead to the rare autosomal recessive neurocutaneous cerebral dysgenesis, neuropathy, ichthyosis, and keratoderma (CEDNIK) syndrome. SNAP29 is a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein. So far, it has been shown to be involved in membrane fusion, epidermal differentiation, formation of primary cilia, and autophagy. Recently, we reported the successful generation of two mouse models for the human CEDNIK syndrome. The aim of this investigation was the generation of a CRISPR/Cas9-mediated SNAP29 knockout (KO) in an immortalized human cell line to further investigate the role of SNAP29 in cellular homeostasis and signaling in humans independently of animal models. Comparison of different methods of delivery for CRISPR/Cas9 plasmids into the cell revealed that lentiviral transduction is more efficient than transfection methods. Here, we reported to the best of our knowledge the first successful generation of a CRISPR/Cas9-mediated SNAP29 KO in immortalized human MRC5Vi fibroblasts (c.169_196delinsTTCGT) via lentiviral transduction.

Cardiac PANK1 Deletion Exacerbates Ventricular Dysfunction During Pressure Overload

2021 ◽  
Author(s):  
Timothy N. Audam ◽  
Caitlin M. Howard ◽  
Lauren F. Garrett ◽  
Yi Wei Zheng ◽  
James A. Bradley ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Biosynthetic Pathway ◽  
Ketone Body ◽  
Cardiac Fibrosis ◽  
Ventricular Dysfunction ◽  
Pressure Overload ◽  
Ventricular Dilation ◽  
The Impact ◽  
Rate Limiting

Coenzyme A (CoA) is an essential co-factor required for intermediary metabolism. Perturbations in homeostasis of CoA have been implicated in various pathologies; however, whether CoA homeostasis is changed and the extent to which CoA levels contribute to ventricular function and remodeling during pressure overload has not been explored. In this study, we sought to assess changes in CoA biosynthetic pathway during pressure overload and determine the impact of limiting CoA on cardiac function. We limited cardiac CoA levels by deleting the rate limiting enzyme in CoA biosynthesis, Pank1. We found that constitutive, cardiomyocyte-specific Pank1 deletion (cmPank1-/-) significantly reduced PANK1 mRNA, PANK1 protein, and CoA levels compared to Pank1 sufficient littermates (cmPank1+/+) but exerted no obvious deleterious impact on the mice at baseline. We then subjected both groups of mice to pressure overload-induced heart failure. Interestingly, there was more ventricular dilation in cmPank1-/- during pressure overload. To explore potential mechanisms contributing to this phenotype, we performed transcriptomic profiling, which suggested a role for Pank1 in regulating fibrotic and metabolic processes during pressure overload. Indeed, Pank1 deletion exacerbated cardiac fibrosis following pressure overload. Because we were interested in the possibility of early metabolic impacts in response to pressure overload, we performed untargeted metabolomics, which indicated significant changes to metabolites involved in fatty acid and ketone metabolism, among other pathways. Collectively, our study underscores the role of elevated CoA levels in supporting fatty acid and ketone body oxidation, which may be more important than CoA-driven, enzyme-independent acetylation in the failing heart.

scholarly journals Role of the glutamate 185 residue in proton translocation mediated by the proton-coupled folate transporter SLC46A1

2009 ◽  
Vol 297 (1) ◽  
pp. C66-C74 ◽  
Author(s):  
Ersin Selcuk Unal ◽  
Rongbao Zhao ◽  
I. David Goldman
Keyword(s):  
Proton Translocation ◽  
Amino Acid Residues ◽  
Loss Of Function ◽  
Wild Type ◽  
Folate Transport ◽  
Rate Limiting Step ◽  
Proximal Small Intestine ◽  
Transport Cycle ◽  
Rate Limiting

The proton-coupled folate transporter (PCFT) SLC46A1 mediates uphill folate transport into enterocytes in proximal small intestine coupled to the inwardly directed proton gradient. Hereditary folate malabsorption is due to loss-of-function mutations in the PCFT gene. This study addresses the functional role of conserved charged amino acid residues within PCFT transmembrane domains with a detailed analysis of the PCFT E185 residue. D156A-, E185A-, E232A-, R148A-, and R376A-PCFT mutants lost function at pH 5.5, as assessed by transient transfection in folate transport-deficient HeLa cells. At pH 7.4, function was preserved only for E185A-PCFT. Loss of function for E185A-PCFT at pH 5.5 was due to an eightfold decrease in the [3H]methotrexate (MTX) influx Vmax; the MTX influx Ktwas identical to that of wild-type (WT)-PCFT (1.5 μM). Consistent with the intrinsic functionality of E185A-PCFT, [3H]MTX influx at pH 5.5 or 7.4 was trans-stimulated in cells preloaded with nonlabeled MTX or 5-formyltetrahydrofolate. Replacement of E185 with Leu, Cys, His, or Gln resulted in a phenotype similar to E185A-PCFT. However, there was greater preservation of activity (∼38% of WT) for the similarly charged E185D-PCFT at pH 5.5. All E185 substitution mutants were biotin accessible at the plasma membrane at a level comparable to WT-PCFT. These observations suggest that the E185 residue plays an important role in the coupled flows of protons and folate mediated by PCFT. Coupling appears to have a profound effect on the maximum rate of transport, consistent with augmentation of a rate-limiting step in the PCFT transport cycle.

scholarly journals Initial Characterization of the Glutamate-Cysteine Ligase Modifier SubunitGclm(−/−) Knockout Mouse

2002 ◽  
Vol 277 (51) ◽  
pp. 49446-49452 ◽  
Author(s):  
Yi Yang ◽  
Matthew Z. Dieter ◽  
Ying Chen ◽  
Howard G. Shertzer ◽  
Daniel W. Nebert ◽  
...  
Keyword(s):  
Null Allele ◽  
Fold Increase ◽  
Environmental Toxicity ◽  
Glutamate Cysteine Ligase ◽  
Enhanced Sensitivity ◽  
Fetal Fibroblasts ◽  
Chemical Oxidants ◽  
Rate Limiting

Glutamate-cysteine ligase (GCL) is the rate-limiting enzyme in the GSH biosynthesis pathway. In higher eukaryotes, this enzyme is a heterodimer comprising a catalytic subunit (GCLC) and a modifier subunit (GCLM), which change the catalytic characteristics of the holoenzyme. To define the cellular function of GCLM, we disrupted the mouseGclmgene to create a null allele.Gclm(−/−) mice are viable and fertile and have no overt phenotype. In liver, lung, pancreas, erythrocytes, and plasma, however, GSH levels inGclm(−/−) mice were 9–16% of that inGclm(+/+) littermates. Cysteine levels inGclm(−/−) mice were 9, 35, and 40% of that inGclm(+/+) mice in kidney, pancreas, and plasma, respectively, but remained unchanged in the liver and erythrocytes. Comparing the hepatic GCL holoenzyme with GCLC in the genetic absence of GCLM, we found the latter had an ∼2-fold increase inKmfor glutamate and a dramatically enhanced sensitivity to GSH inhibition. The major decrease in GSH, combined with diminished GCL activity, renderedGclm(−/−) fetal fibroblasts strikingly more sensitive to chemical oxidants such as H2O2. We conclude that theGclm(−/−) mouse represents a model of chronic GSH depletion that will be very useful in evaluating the role of the GCLM subunit and GSH in numerous pathophysiological conditions as well as in environmental toxicity associated with oxidant insult.

scholarly journals Biological and Regulatory Properties of Vav-3, a New Member of the Vav Family of Oncoproteins

1999 ◽  
Vol 19 (11) ◽  
pp. 7870-7885 ◽  
Author(s):  
Nieves Movilla ◽  
Xosé R. Bustelo
Keyword(s):  
Tyrosine Kinases ◽  
Protein Tyrosine Kinases ◽  
Nucleotide Exchange ◽  
Loss Of Function ◽  
Wild Type ◽  
Gtp Binding ◽  
Regulatory Properties ◽  
Identification And Characterization

ABSTRACT We report here the identification and characterization of a novel Vav family member, Vav-3. Signaling experiments demonstrate that Vav-3 participates in pathways activated by protein tyrosine kinases. Vav-3 promotes the exchange of nucleotides on RhoA, on RhoG and, to a lesser extent, on Rac-1. During this reaction, Vav-3 binds physically to the nucleotide-free states of those GTPases. These functions are stimulated by tyrosine phosphorylation in wild-type Vav-3 and become constitutively activated upon deletion of the entire calponin-homology region. Expression of truncated versions of Vav-3 leads to drastic actin relocalization and to the induction of stress fibers, lamellipodia, and membrane ruffles. Moreover, expression of Vav-3 alters cytokinesis, resulting in the formation of binucleated cells. All of these responses need only the expression of the central region of Vav-3 encompassing the Dbl homology (DH), pleckstrin homology (PH), and zinc finger (ZF) domains but do not require the presence of the C-terminal SH3-SH2-SH3 regions. Studies conducted with Vav-3 proteins containing loss-of-function mutations in the DH, PH, and ZF regions indicate that only the DH and ZF regions are essential for Vav-3 biological activity. Finally, we show that one of the functions of the Vav-3 ZF region is to work coordinately with the catalytic DH region to promote both the binding to GTP-hydrolases and their GDP-GTP nucleotide exchange. These results highlight the role of Vav-3 in signaling and cytoskeletal pathways and identify a novel functional cross-talk between the DH and ZF domains of Vav proteins that is imperative for the binding to, and activation of, Rho GTP-binding proteins.

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