scholarly journals ToxCast chemical library screen identifies diethanolamine as an activator of Wnt signaling

2021 ◽  
Author(s):  
Justin M. Wolter ◽  
Jessica A. Jimenez ◽  
Jason L. Stein ◽  
Mark J. Zylka
Keyword(s):  
Wnt Signaling ◽  
Human Exposure ◽  
Neural Progenitor Cell ◽  
Autism Spectrum ◽  
Chemical Library ◽  
Gain Of Function ◽  
Agricultural Pesticides ◽  
Library Screen ◽  
Hormone Analogs ◽  
Mutant Construct

AbstractNumerous autism spectrum disorder (ASD) risk genes are associated with Wnt signaling, suggesting that brain development may be especially sensitive to genetic perturbation of this pathway. Additionally, valproic acid, which modulates Wnt signaling, increases risk for ASD when taken during pregnancy. We previously found that an autism-linked gain-of-function UBE3AT485A mutant construct hyperactivated canonical Wnt signaling, providing a genetic means to elevate Wnt signaling above baseline levels. To identify environmental use chemicals that enhance or suppress Wnt signaling, we screened the ToxCast Phase I and II libraries in cells expressing this autism linked UBE3AT485 gain-of-function mutant construct. Using structural comparisons, we identify classes of chemicals that stimulated Wnt signaling, including ethanolamines, as well as chemicals that inhibited Wnt signaling, such as agricultural pesticides, and synthetic hormone analogs. To prioritize chemicals for follow-up, we leveraged predicted human exposure data, and identified diethanolamine (DEA) as a chemical that both stimulates Wnt signaling in UBE3AT485A–transfected cells and has a high potential for prenatal exposure in humans. DEA also enhanced proliferation in two primary human neural progenitor cell lines. Overall, this study identifies chemicals with the potential for human exposure that influence Wnt signaling in human cells.

scholarly journals Newly Identified Antibacterial Compounds Are Topoisomerase Poisons in African Trypanosomes

2009 ◽  
Vol 54 (2) ◽  
pp. 620-626 ◽  
Author(s):  
Sonya C. Tang ◽  
Theresa A. Shapiro
Keyword(s):  
Topoisomerase Ii ◽  
Protozoan Parasite ◽  
New Drugs ◽  
Chemical Library ◽  
African Trypanosomes ◽  
Topoisomerase Poisons ◽  
Type Ia ◽  
Library Screen ◽  
Circular Dnas ◽  
Current Therapies

ABSTRACT Human African trypanosomiasis, caused by the Trypanosoma brucei protozoan parasite, is fatal when left untreated. Current therapies are antiquated, and there is a need for new pharmacologic agents against T. brucei targets that have no human ortholog. Trypanosomes have a single mitochondrion with a unique mitochondrial DNA, known as kinetoplast DNA (kDNA), a topologically complex network that contains thousands of interlocking circular DNAs, termed minicircles (∼1 kb) and maxicircles (∼23 kb). Replication of kDNA depends on topoisomerases, enzymes that catalyze reactions that change DNA topology. T. brucei has an unusual type IA topoisomerase that is dedicated to kDNA metabolism. This enzyme has no ortholog in humans, and RNA interference (RNAi) studies have shown that it is essential for parasite survival, making it an ideal drug target. In a large chemical library screen, two compounds were recently identified as poisons of bacterial topoisomerase IA. We found that these compounds are trypanocidal in the low micromolar range and that they promote the formation of linearized minicircles covalently bound to protein on the 5′ end, consistent with the poisoning of mitochondrial topoisomerase IA. Surprisingly, however, band depletion studies showed that it is topoisomerase IImt, and not topoisomerase IAmt, that is trapped. Both compounds are planar aromatic polycyclic structures that intercalate into and unwind DNA. These findings reinforce the utility of topoisomerase IImt as a target for development of new drugs for African sleeping sickness.

scholarly journals New gain-of-function mutation shows CACNA1D as recurrently mutated gene in autism spectrum disorders and epilepsy

2017 ◽  
Vol 26 (15) ◽  
pp. 2923-2932 ◽  
Author(s):  
Alexandra Pinggera ◽  
Luisa Mackenroth ◽  
Andreas Rump ◽  
Jens Schallner ◽  
Filippo Beleggia ◽  
...  
Keyword(s):  
Autism Spectrum Disorders ◽  
Autism Spectrum ◽  
Gain Of Function ◽  
Spectrum Disorders

scholarly journals Biophysical classification of a CACNA1D de novo mutation as a high-risk mutation for a severe neurodevelopmental disorder

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nadja T. Hofer ◽  
Petronel Tuluc ◽  
Nadine J. Ortner ◽  
Yuliia V. Nikonishyna ◽  
Monica L. Fernándes-Quintero ◽  
...  
Keyword(s):  
High Risk ◽  
Neurodevelopmental Disorders ◽  
Developmental Disorder ◽  
De Novo ◽  
Disease Risk ◽  
Neurodevelopmental Disorder ◽  
Autism Spectrum ◽  
De Novo Mutation ◽  
Loss Of Function ◽  
Gain Of Function

Abstract Background There is increasing evidence that de novo CACNA1D missense mutations inducing increased Cav1.3 L-type Ca2+-channel-function confer a high risk for neurodevelopmental disorders (autism spectrum disorder with and without neurological and endocrine symptoms). Electrophysiological studies demonstrating the presence or absence of typical gain-of-function gating changes could therefore serve as a tool to distinguish likely disease-causing from non-pathogenic de novo CACNA1D variants in affected individuals. We tested this hypothesis for mutation S652L, which has previously been reported in twins with a severe neurodevelopmental disorder in the Deciphering Developmental Disorder Study, but has not been classified as a novel disease mutation. Methods For functional characterization, wild-type and mutant Cav1.3 channel complexes were expressed in tsA-201 cells and tested for typical gain-of-function gating changes using the whole-cell patch-clamp technique. Results Mutation S652L significantly shifted the voltage-dependence of activation and steady-state inactivation to more negative potentials (~ 13–17 mV) and increased window currents at subthreshold voltages. Moreover, it slowed tail currents and increased Ca2+-levels during action potential-like stimulations, characteristic for gain-of-function changes. To provide evidence that only gain-of-function variants confer high disease risk, we also studied missense variant S652W reported in apparently healthy individuals. S652W shifted activation and inactivation to more positive voltages, compatible with a loss-of-function phenotype. Mutation S652L increased the sensitivity of Cav1.3 for inhibition by the dihydropyridine L-type Ca2+-channel blocker isradipine by 3–4-fold. Conclusions and limitations Our data provide evidence that gain-of-function CACNA1D mutations, such as S652L, but not loss-of-function mutations, such as S652W, cause high risk for neurodevelopmental disorders including autism. This adds CACNA1D to the list of novel disease genes identified in the Deciphering Developmental Disorder Study. Although our study does not provide insight into the cellular mechanisms of pathological Cav1.3 signaling in neurons, we provide a unifying mechanism of gain-of-function CACNA1D mutations as a predictor for disease risk, which may allow the establishment of a more reliable diagnosis of affected individuals. Moreover, the increased sensitivity of S652L to isradipine encourages a therapeutic trial in the two affected individuals. This can address the important question to which extent symptoms are responsive to therapy with Ca2+-channel blockers.

scholarly journals An in vivo chemical library screen in Xenopus tadpoles reveals novel pathways involved in angiogenesis and lymphangiogenesis

Blood ◽  
2009 ◽  
Vol 114 (5) ◽  
pp. 1110-1122 ◽  
Author(s):  
Roland E. Kälin ◽  
Nadja E. Bänziger-Tobler ◽  
Michael Detmar ◽  
André W. Brändli
Keyword(s):  
Cancer Metastasis ◽  
Screening Strategy ◽  
In Vitro Assays ◽  
Chemical Library ◽  
Edema Formation ◽  
Depth Analysis ◽  
Library Screen ◽  
Lymphatic Development

Abstract Angiogenesis and lymphangiogenesis are essential for organogenesis but also play important roles in tissue regeneration, chronic inflammation, and tumor progression. Here we applied in vivo forward chemical genetics to identify novel compounds and biologic mechanisms involved in (lymph)angiogenesis in Xenopus tadpoles. A novel 2-step screening strategy involving a simple phenotypic read-out (edema formation or larval lethality) followed by semiautomated in situ hybridization was devised and used to screen an annotated chemical library of 1280 bioactive compounds. We identified 32 active compounds interfering with blood vascular and/or lymphatic development in Xenopus. Selected compounds were also tested for activities in a variety of endothelial in vitro assays. Finally, in a proof-of-principle study, the adenosine A1 receptor antagonist 7-chloro-4-hydroxy-2-phenyl-1,8-naphthyridine, an inhibitor of blood vascular and lymphatic development in Xenopus, was shown to act also as a potent antagonist of VEGFA-induced adult neovascularization in mice. Taken together, the present chemical library screening strategy in Xenopus tadpoles represents a rapid and highly efficient approach to identify novel pathways involved in (lymph)angiogenesis. In addition, the recovered compounds represent a rich resource for in-depth analysis, and their drug-like features will facilitate further evaluation in preclinical models of inflammation and cancer metastasis.

scholarly journals Gain-of-function defects of astrocytic Kir4.1 channels in children with autism spectrum disorders and epilepsy

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Federico Sicca ◽  
Elena Ambrosini ◽  
Maria Marchese ◽  
Luigi Sforna ◽  
Ilenio Servettini ◽  
...  
Keyword(s):  
Autism Spectrum Disorders ◽  
Children With Autism ◽  
Autism Spectrum ◽  
Gain Of Function ◽  
Spectrum Disorders
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