scholarly journals Human neural networks with sparse TDP-43 pathology reveal NPTX2 misregulation in ALS/FTLD

2021 ◽  
Author(s):  
Marian Hruska-Plochan ◽  
Katharina M Hembach ◽  
Silvia Ronchi ◽  
Vera I Wiersma ◽  
Zuzanna Maniecka ◽  
...  
Keyword(s):  
Functional Networks ◽  
Loss Of Function ◽  
Wild Type ◽  
Cellular Models ◽  
Self Organized ◽  
Rna Targets ◽  
Age Dependent ◽  
Manual Selection ◽  
Selection Of ◽  
Human Specific

Human cellular models of neurodegeneration require reproducibility and longevity, which is necessary for simulating these age-dependent diseases. Such systems are particularly needed for TDP-43 proteinopathies, which involve human-specific mechanisms that cannot be directly studied in animal models. To explore the emergence and consequences of TDP-43 pathologies, we generated iPSC-derived, colony morphology neural stem cells (iCoMoNSCs) via manual selection of neural precursors. Single-cell transcriptomics (scRNA-seq) and comparison to independent NSCs, showed that iCoMoNSCs are uniquely homogenous and self-renewing. Differentiated iCoMoNSCs formed a self-organized multicellular system consisting of synaptically connected and electrophysiologically active neurons, which matured into long-lived functional networks. Neuronal and glial maturation in iCoMoNSC-derived cultures was similar to that of cortical organoids. Overexpression of wild-type TDP-43 in a minority of iCoMoNSC-derived neurons led to progressive fragmentation and aggregation, resulting in loss of function and neurotoxicity. scRNA-seq revealed a novel set of misregulated RNA targets coinciding in both TDP-43 overexpressing neurons and patient brains exhibiting loss of nuclear TDP-43. The strongest misregulated target encoded for the synaptic protein NPTX2, which was consistently misaccumulated in ALS and FTLD patient neurons with TDP-43 pathology. Our work directly links TDP-43 misregulation and NPTX2 accumulation, thereby highlighting a new pathway of neurotoxicity.

scholarly journals Age-Dependent and Sleep/Seizure-Induced Pathomechanisms of Autosomal Dominant Sleep-Related Hypermotor Epilepsy

2020 ◽  
Vol 21 (21) ◽  
pp. 8142 ◽  
Author(s):  
Kouji Fukuyama ◽  
Motohiro Okada
Keyword(s):  
Plasma Membrane ◽  
Autosomal Dominant ◽  
Loss Of Function ◽  
Glutamatergic Transmission ◽  
Wild Type ◽  
Cx43 Expression ◽  
Nicotine Administration ◽  
Extracellular Signal ◽  
Age Dependent ◽  
Before And After

The loss-of-function S284L-mutant α4 subunit of the nicotinic acetylcholine receptor (nAChR) is considered to contribute to the pathomechanism of autosomal dominant sleep-related hypermotor epilepsy (ADSHE); however, the age-dependent and sleep-related pathomechanisms of ADSHE remain to be clarified. To explore the age-dependent and sleep-induced pathomechanism of ADSHE, the present study determined the glutamatergic transmission abnormalities associated with α4β2-nAChR and the astroglial hemichannel in the hyperdirect and corticostriatal pathways of ADSHE model transgenic rats (S286L-TG) bearing the rat S286L-mutant Chrna4 gene corresponding to the human S284L-mutant CHRNA4 gene of ADSHE, using multiprobe microdialysis and capillary immunoblotting analyses. This study could not detect glutamatergic transmission in the corticostriatal pathway from the orbitofrontal cortex (OFC) to the striatum. Before ADSHE onset (four weeks of age), functional abnormalities of glutamatergic transmission compared to the wild-type in the cortical hyperdirect pathway, from OFC to the subthalamic nucleus (STN) in S286L-TG, could not be detected. Conversely, after ADSHE onset (eight weeks of age), glutamatergic transmission in the hyperdirect pathway of S286L-TG was enhanced compared to the wild-type. Notably, enhanced glutamatergic transmission of S286L-TG was revealed by hemichannel activation in the OFC. Expression of connexin43 (Cx43) in the OFC of S286L-TG was upregulated after ADSHE onset but was almost equal to the wild-type prior to ADSHE onset. Differences in the expression of phosphorylated protein kinase B (pAkt) before ADSHE onset between the wild-type and S286L-TG were not observed; however, after ADSHE onset, pAkt was upregulated in S286L-TG. Conversely, the expression of phosphorylated extracellular signal-regulated kinase (pErk) was already upregulated before ADSHE onset compared to the wild-type. Both before and after ADSHE onset, subchronic nicotine administration decreased and did not affect the both expression of Cx43 and pErk of respective wild-type and S286L-TG, whereas the pAkt expression of both the wild-type and S286L-TG was increased by nicotine. Cx43 expression in the plasma membrane of the primary cultured astrocytes of the wild-type was increased by elevation of the extracellular K+ level (higher than 10 mM), and the increase in Cx43 expression in the plasma membrane required pErk functions. These observations indicate that a combination of functional abnormalities, GABAergic disinhibition, and upregulated pErk induced by the loss-of-function S286L-mutant α4β2-nAChR contribute to the age-dependent and sleep-induced pathomechanism of ADSHE via the upregulation/hyperactivation of the Cx43 hemichannels.

scholarly journals DJ-1 inhibits microglial activation and protects dopaminergic neurons in vitro and in vivo through interacting with microglial p65

2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Zixuan Lin ◽  
Chen Chen ◽  
Dongqin Yang ◽  
Jianqing Ding ◽  
Guanghui Wang ◽  
...  
Keyword(s):  
Microglial Activation ◽  
Nuclear Translocation ◽  
Substantia Nigra Pars Compacta ◽  
Loss Of Function ◽  
Wild Type ◽  
Wild Type Littermate ◽  
Cellular Models ◽  
Bv2 Cells

AbstractParkinson’s disease (PD), one of the most common neurodegenerative disorders, is characterized by progressive neurodegeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc). DJ-1 acts essential roles in neuronal protection and anti-neuroinflammatory response, and its loss of function is tightly associated with a familial recessive form of PD. However, the molecular mechanism of DJ-1 involved in neuroinflammation is largely unclear. Here, we found that wild-type DJ-1, rather than the pathogenic L166P mutant DJ-1, directly binds to the subunit p65 of nuclear factor-κB (NF-κB) in the cytoplasm, and loss of DJ-1 promotes p65 nuclear translocation by facilitating the dissociation between p65 and NF-κB inhibitor α (IκBα). DJ-1 knockout (DJ-1−/−) mice exhibit more microglial activation compared with wild-type littermate controls, especially in response to lipopolysaccharide (LPS) treatment. In cellular models, knockdown of DJ-1 significantly upregulates the gene expression and increases the release of LPS-treated inflammatory cytokines in primary microglia and BV2 cells. Furthermore, DJ-1 deficiency in microglia significantly enhances the neuronal toxicity in response to LPS stimulus. In addition, pharmacological blockage of NF-κB nuclear translocation by SN-50 prevents microglial activation and alleviates the damage of DA neurons induced by microglial DJ-1 deficiency in vivo and in vitro. Thus, our data illustrate a novel mechanism by which DJ-1 facilitates the interaction between IκBα and p65 by binding to p65 in microglia, and thus repressing microglial activation and exhibiting the protection of DA neurons from neuroinflammation-mediated injury in PD.

scholarly journals A method for rapid selection of randomly induced mutations in a gene of interest using CRISPR/Cas9 mediated activation of gene expression

2019 ◽  
Author(s):  
William A. Ng ◽  
Andrew Ma ◽  
Molly Chen ◽  
Bruce H. Reed
Keyword(s):  
Gene Expression ◽  
Screening Strategy ◽  
Loss Of Function ◽  
Wild Type ◽  
Induced Mutations ◽  
Allelic Series ◽  
Lethal Mutations ◽  
F1 Progeny ◽  
Genetic Cross ◽  
Selection Of

AbstractWe have developed a CRISPR/Cas9 based method for isolating randomly induced recessive lethal mutations in a gene of interest (GOI) by selection within the F1 progeny of a single genetic cross. Our method takes advantage of the ability to overexpress a GOI using CRISPR/Cas9 mediated activation of gene expression. In essence, the screening strategy is based upon the idea that if overexpression of a wild type allele can generate a phenotype, then overexpression of a newly induced loss-of-function allele will lack this phenotype. As a proof-of-principle, we used this method to select EMS induced mutations of the Drosophila gene hindsight (hnt). From approximately 45,000 F1 progeny we recovered 8 new EMS induced loss-of-function hnt alleles that we characterized as an allelic series of hypomorphic mutations. This new method can, in theory, be used to recover randomly induced point mutants in a GOI and can be applied to any circumstance where CRISPR/Cas9 mediated activation of gene expression is associated with lethality or a visible phenotype.

scholarly journals A Method for Rapid Selection of Randomly Induced Mutations in a Gene of Interest Using CRISPR/Cas9 Mediated Activation of Gene Expression

2020 ◽  
Vol 10 (6) ◽  
pp. 1893-1901
Author(s):  
William A. Ng ◽  
Andrew Ma ◽  
Molly Chen ◽  
Bruce H. Reed
Keyword(s):  
Gene Expression ◽  
Screening Strategy ◽  
Loss Of Function ◽  
Wild Type ◽  
Induced Mutations ◽  
Allelic Series ◽  
Lethal Mutations ◽  
F1 Progeny ◽  
Genetic Cross ◽  
Selection Of

We have developed a CRISPR/Cas9 based method for isolating randomly induced recessive lethal mutations in a gene of interest (GOI) by selection within the F1 progeny of a single genetic cross. Our method takes advantage of the ability to overexpress a GOI using CRISPR/Cas9 mediated activation of gene expression. In essence, the screening strategy is based upon the idea that if overexpression of a wild type allele can generate a phenotype, then overexpression of a newly induced loss-of-function allele will lack this phenotype. As a proof-of-principle, we used this method to select EMS induced mutations of the Drosophila gene hindsight (hnt). From approximately 45,000 F1 progeny we recovered 8 new EMS induced loss-of-function hnt alleles that we characterized as an allelic series of hypomorphic mutations. This new method can, in theory, be used to recover randomly induced point mutants in a GOI and can be applied to any circumstance where CRISPR/Cas9 mediated activation of gene expression is associated with lethality or a visible phenotype.

scholarly journals Reconstructing a wild-type Pseudomonas aeruginosa reference strain PAO1

2021 ◽  
Author(s):  
Samuel Lee ◽  
Larry Gallagher ◽  
Colin Manoil
Keyword(s):  
Reference Strain ◽  
Genetic Selection ◽  
Loss Of Function ◽  
Wild Type ◽  
Regulatory Mutation ◽  
Phenotypic Analysis ◽  
Strain Pao1 ◽  
Suppressor Mutations ◽  
Wild Type Parent ◽  
Selection Of

The P. aeruginosa reference strain PAO1 has been used to delineate much of the physiology, metabolism and fundamental biology of the species. The wild-type parent of PAO1 was lost, and PAO1 carries a regulatory mutation introduced for positive genetic selection that affects antibiotic resistance, virulence, quorum sensing and other traits. The mutation is a loss-of-function change in an oxidoreductase gene (mexS), which constitutively activates a stress response controlled by a positive regulator (MexT). Fitness defects associated with the constitutive response have led to the inadvertent selection of mexT– suppressor mutations, creating genetic heterogeneity in PAO1 sublines studied in different laboratories. To help circumvent complications due to the mexS–minus phenotypes, we created a wild-type version of PAO1 (called LPAO) by “reverting” its mexS to the functional allele likely to have been in its parent. Phenotypic analysis revealed that the mexS– allele in PAO1 makes growth sensitive to salt (NaCl) and is lethal when combined with mutations inactivating the major sodium antiporter (ShaABCDEF). The salt sensitivity of PAO1 may underlie some complex mexS– phenotypes and help explain the selection of mexT– suppressor mutations. To facilitate genetic comparisons of PAO1, LPAO and other P. aeruginosa strains, we developed a transformation procedure to transfer selectable alleles, such as transposon insertion alleles, between strains. Overall, the study helps explain phenotypic heterogeneity of PAO1-derived strains and provides resources to help recognize and eliminate difficulties due to it. IMPORTANCE The P. aeruginosa reference strain PAO1 carries a regulatory mutation that may affect processes characterized in it. To eliminate complications due to the mutation, we constructed a version of the missing wild-type parent strain and developed methods to transfer mutations between PAO1 and the new strain. The methods are likely to be applicable to other isolates of P. aeruginosa as well.

scholarly journals Haploinsufficiency of TANK-binding kinase 1 prepones age-associated neuroinflammatory changes without causing motor neuron degeneration in aged mice

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Clara Bruno ◽  
Kirsten Sieverding ◽  
Axel Freischmidt ◽  
Takashi Satoh ◽  
Paul Walther ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Frontotemporal Dementia ◽  
Gene Expression Pattern ◽  
Incomplete Penetrance ◽  
Immune Gene ◽  
Loss Of Function ◽  
Wild Type ◽  
Age Dependent ◽  
Old Mice ◽  
Lateral Sclerosis

Abstract Loss-of-function mutations in TANK-binding kinase 1 cause genetic amyotrophic lateral sclerosis and frontotemporal dementia. Consistent with incomplete penetrance in humans, haploinsufficiency of TANK-binding kinase 1 did not cause motor symptoms in mice up to 7 months of age in a previous study. Ageing is the strongest risk factor for neurodegenerative diseases. Hypothesizing that age-dependent processes together with haploinsufficiency of TANK-binding kinase 1 could create a double hit situation that may trigger neurodegeneration, we examined mice with hemizygous deletion of Tbk1 (Tbk1+/− mice) and wild-type siblings up to 22 months. Compared to 4-month old mice, aged, 22-month old mice showed glial activation, deposition of motoneuronal p62 aggregates, muscular denervation and profound transcriptomic alterations in a set of 800 immune-related genes upon ageing. However, we did not observe differences regarding these measures between aged Tbk1+/− and wild-type siblings. High age did also not precipitate TAR DNA-binding protein 43 aggregation, neurodegeneration or a neurological phenotype in Tbk1+/− mice. In young Tbk1+/− mice, however, we found the CNS immune gene expression pattern shifted towards the age-dependent immune system dysregulation observed in old mice. Conclusively, ageing is not sufficient to precipitate an amyotrophic lateral sclerosis or frontotemporal dementia phenotype or spinal or cortical neurodegeneration in a model of Tbk1 haploinsufficiency. We hypothesize that the consequences of Tbk1 haploinsufficiency may be highly context-dependent and require a specific synergistic stress stimulus to be uncovered.

scholarly journals Distinct sub-cellular autophagy impairments occur independently of protein aggregation in induced neurons from patients with Huntington’s disease

2021 ◽  
Author(s):  
Karolina Pircs ◽  
Janelle Drouin-Ouellet ◽  
Jeovanis Gil ◽  
Melinda Rezeli ◽  
Daniela A. Grassi ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Direct Reprogramming ◽  
Wild Type ◽  
Cellular Models ◽  
Cellular Autophagy ◽  
Age Dependent ◽  
Induced Neurons ◽  
Neuronal Autophagy

AbstractHuntington’s disease (HD) is a neurodegenerative disorder caused by CAG expansions in the huntingtin (HTT) gene. Modelling HD has remained challenging, as rodent and cellular models poorly recapitulate the disease. To address this, we generated induced neurons (iNs) through direct reprogramming of human skin fibroblasts, which retain age-dependent epigenetic characteristics. HD-iNs displayed profound deficits in autophagy, characterised by reduced transport of late autophagic structures from the neurites to the soma. The neurite-specific alterations in autophagy resulted in shorter, thinner and fewer neurites presented by HD-iNs. CRISPRi-mediated silencing of HTT did not rescue this phenotype but rather resulted in additional autophagy alterations in ctrl-iNs, highlighting the importance of wild type HTT in neuronal autophagy. In summary, our work identifies a distinct subcellular autophagy impairment in aged patient derived HD-neurons and provides a new rational for future development of autophagy activation therapies.

scholarly journals Mutations in fbiD (Rv2983) as a Novel Determinant of Resistance to Pretomanid and Delamanid in Mycobacterium tuberculosis

2020 ◽  
Vol 65 (1) ◽  
pp. e01948-20
Author(s):  
Dalin Rifat ◽  
Si-Yang Li ◽  
Thomas Ioerger ◽  
Keshav Shah ◽  
Jean-Philippe Lanoix ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Evidence ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Wild Type ◽  
Content Type ◽  
Solid Media ◽  
High Level ◽  
Level Resistance

ABSTRACTThe nitroimidazole prodrugs delamanid and pretomanid comprise one of only two new antimicrobial classes approved to treat tuberculosis (TB) in 50 years. Prior in vitro studies suggest a relatively low barrier to nitroimidazole resistance in Mycobacterium tuberculosis, but clinical evidence is limited to date. We selected pretomanid-resistant M. tuberculosis mutants in two mouse models of TB using a range of pretomanid doses. The frequency of spontaneous resistance was approximately 10−5 CFU. Whole-genome sequencing of 161 resistant isolates from 47 mice revealed 99 unique mutations, of which 91% occurred in 1 of 5 genes previously associated with nitroimidazole activation and resistance, namely, fbiC (56%), fbiA (15%), ddn (12%), fgd (4%), and fbiB (4%). Nearly all mutations were unique to a single mouse and not previously identified. The remaining 9% of resistant mutants harbored mutations in Rv2983 (fbiD), a gene not previously associated with nitroimidazole resistance but recently shown to be a guanylyltransferase necessary for cofactor F420 synthesis. Most mutants exhibited high-level resistance to pretomanid and delamanid, although Rv2983 and fbiB mutants exhibited high-level pretomanid resistance but relatively small changes in delamanid susceptibility. Complementing an Rv2983 mutant with wild-type Rv2983 restored susceptibility to pretomanid and delamanid. By quantifying intracellular F420 and its precursor Fo in overexpressing and loss-of-function mutants, we provide further evidence that Rv2983 is necessary for F420 biosynthesis. Finally, Rv2983 mutants and other F420H2-deficient mutants displayed hypersusceptibility to some antibiotics and to concentrations of malachite green found in solid media used to isolate and propagate mycobacteria from clinical samples.

scholarly journals The NALCN Channel Regulator UNC-80 Functions in a Subset of Interneurons To Regulate Caenorhabditis elegans Reversal Behavior

2019 ◽  
Vol 10 (1) ◽  
pp. 199-210 ◽  
Author(s):  
Chuanman Zhou ◽  
Jintao Luo ◽  
Xiaohui He ◽  
Qian Zhou ◽  
Yunxia He ◽  
...  
Keyword(s):  
Plant Hormone ◽  
Neuronal Excitability ◽  
Resting Membrane Potential ◽  
Loss Of Function ◽  
Wild Type ◽  
C Elegans ◽  
Link Type ◽  
Complex Functions ◽  
And Function ◽  
Multiple Loss

NALCN (Na+leak channel, non-selective) is a conserved, voltage-insensitive cation channel that regulates resting membrane potential and neuronal excitability. UNC79 and UNC80 are key regulators of the channel function. However, the behavioral effects of the channel complex are not entirely clear and the neurons in which the channel functions remain to be identified. In a forward genetic screen for C. elegans mutants with defective avoidance response to the plant hormone methyl salicylate (MeSa), we isolated multiple loss-of-function mutations in unc-80 and unc-79. C. elegans NALCN mutants exhibited similarly defective MeSa avoidance. Interestingly, NALCN, unc-80 and unc-79 mutants all showed wild type-like responses to other attractive or repelling odorants, suggesting that NALCN does not broadly affect odor detection or related forward and reversal behaviors. To understand in which neurons the channel functions, we determined the identities of a subset of unc-80-expressing neurons. We found that unc-79 and unc-80 are expressed and function in overlapping neurons, which verified previous assumptions. Neuron-specific transgene rescue and knockdown experiments suggest that the command interneurons AVA and AVE and the anterior guidepost neuron AVG can play a sufficient role in mediating unc-80 regulation of the MeSa avoidance. Though primarily based on genetic analyses, our results further imply that MeSa might activate NALCN by direct or indirect actions. Altogether, we provide an initial look into the key neurons in which the NALCN channel complex functions and identify a novel function of the channel in regulating C. elegans reversal behavior through command interneurons.

scholarly journals Putative transmembrane transporter modulates higher-level aggression in Drosophila

2017 ◽  
Vol 114 (9) ◽  
pp. 2373-2378 ◽  
Author(s):  
Budhaditya Chowdhury ◽  
Yick-Bun Chan ◽  
Edward A. Kravitz
Keyword(s):  
Causal Effect ◽  
Nerve Terminals ◽  
Rna Seq ◽  
Wild Type ◽  
Temperature Dependent ◽  
Number Of Genes ◽  
Interesting Family ◽  
Solute Carrier ◽  
Transmembrane Transporter ◽  
Selection Of

By selection of winners of dyadic fights for 35 generations, we have generated a hyperaggressive Bully line of flies that almost always win fights against the parental wild-type Canton-S stock. Maintenance of the Bully phenotype is temperature dependent during development, with the phenotype lost when flies are reared at 19 °C. No similar effect is seen with the parent line. This difference allowed us to carry out RNA-seq experiments and identify a limited number of genes that are differentially expressed by twofold or greater in the Bullies; one of these was a putative transmembrane transporter, CG13646, which showed consistent and reproducible twofold down-regulation in Bullies. We examined the causal effect of this gene on the phenotype with a mutant line for CG13646, and with an RNAi approach. In all cases, reduction in expression of CG13646 by approximately half led to a hyperaggressive phenotype partially resembling that seen in the Bully flies. This gene is a member of a very interesting family of solute carrier proteins (SLCs), some of which have been suggested as being involved in glutamine/glutamate and GABA cycles of metabolism in excitatory and inhibitory nerve terminals in mammalian systems.

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