scholarly journals Analgesia linked to Nav1.7 loss of function requires μ and δ opioid receptors

2018 ◽  
Author(s):  
Vanessa Pereira ◽  
Queensta Millet ◽  
Jose Aramburu ◽  
Cristina Lopez-Rodriguez ◽  
Claire Gaveriaux Ruff ◽  
...  
Keyword(s):  
Opioid Receptors ◽  
Neurotransmitter Release ◽  
Null Mouse ◽  
Channel Blockers ◽  
Loss Of Function ◽  
Analgesic Drug ◽  
Gene Encoding ◽  
Binding Motifs ◽  
Opioid Receptor Antagonists ◽  
Endogenous Enkephalins

AbstractFunctional deletion of the SCN9A gene encoding sodium channel Nav1.7 makes humans and mice pain-free (1,2). Opioid signaling contributes to this analgesic state (3). Here we show that the pharmacological block or deletion of both μ and δ opioid receptors is required to abolish Nav1.7 null opioid-related analgesia.κ-opioid receptor antagonists were without effect. Enkephalins encoded by the Penk gene are upregulated in Nav1.7 nulls (3). Deleting Nfat5, a transcription factor with binding motifs upstream of Penk (4), induces the same level of enkephalin mRNA expression as found in Nav1.7 nulls, but without consequent analgesia. These data confirm that a combination of events linked to SCN9A gene loss is required for analgesia. Higher levels of endogenous enkephalins (3), potentiated opioid receptors (5), diminished electrical excitability (6,7) and loss of neurotransmitter release (2,1) together contribute to the analgesic phenotype found in Nav1.7 null mouse and human mutants. These observations help explain the failure of Nav1.7 channel blockers alone to produce analgesia and suggest new routes for analgesic drug development.

scholarly journals Analgesia linked to Nav1.7 loss of function requires µ- and δ-opioid receptors

2018 ◽  
Vol 3 ◽  
pp. 101 ◽  
Author(s):  
Vanessa Pereira ◽  
Queensta Millet ◽  
Jose Aramburu ◽  
Cristina Lopez-Rodriguez ◽  
Claire Gaveriaux-Ruff ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Opioid Receptor ◽  
Opioid Receptors ◽  
Mutant Mice ◽  
Null Mouse ◽  
Channel Blockers ◽  
Null Mutant ◽  
Receptor Antagonists ◽  
Opioid Receptor Antagonists ◽  
Null Mutant Mice

Background: Functional deletion of the Scn9a (sodium voltage-gated channel alpha subunit 9) gene encoding sodium channel Nav1.7 makes humans and mice pain-free. Opioid signalling contributes to this analgesic state. We have used pharmacological and genetic approaches to identify the opioid receptors involved in this form of analgesia. We also examined the regulation of proenkephalin expression by the transcription factor Nfat5 that binds upstream of the Penk gene. Methods: We used specific µ-, δ- and κ-opioid receptor antagonists alone or in combination to examine which opioid receptors were necessary for Nav1.7 loss-associated analgesia in mouse behavioural assays of thermal pain. We also used µ- and δ-opioid receptor null mutant mice alone and in combination in behavioural assays to examine the role of these receptors in Nav1.7 knockouts pain free phenotype. Finally, we examined the levels of Penk mRNA in Nfat5-null mutant mice, as this transcription factor binds to consensus sequences upstream of the Penk gene. Results: The pharmacological block or deletion of both µ- and δ-opioid receptors was required to abolish Nav1.7-null opioid-related analgesia. κ-opioid receptor antagonists were without effect. Enkephalins encoded by the Penk gene are upregulated in Nav1.7 nulls. Deleting Nfat5, a transcription factor with binding motifs upstream of Penk, induces the same level of enkephalin mRNA expression as found in Nav1.7 nulls, but without consequent analgesia. These data confirm that a combination of events linked to Scn9a gene loss is required for analgesia. Higher levels of endogenous enkephalins, potentiated opioid receptors, diminished electrical excitability and loss of neurotransmitter release together contribute to the analgesic phenotype found in Nav1.7-null mouse and human mutants. Conclusions: These observations help explain the failure of Nav1.7 channel blockers alone to produce analgesia and suggest new routes for analgesic drug development.

scholarly journals Gain-of-function GABRB3 variants identified in vigabatrin-hypersensitive epileptic encephalopathies

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Nathan L Absalom ◽  
Vivian W Y Liao ◽  
Kavitha Kothur ◽  
Dinesh C Indurthi ◽  
Bruce Bennetts ◽  
...  
Keyword(s):  
De Novo ◽  
Drug Effects ◽  
Receptor Expression ◽  
Aminobutyric Acid ◽  
Loss Of Function ◽  
Molecular Phenotype ◽  
Gain Of Function ◽  
Gene Encoding ◽  
Epileptic Encephalopathies ◽  
Receptor Phenotype

Abstract Variants in the GABRB3 gene encoding the β3-subunit of the γ-aminobutyric acid type A ( receptor are associated with various developmental and epileptic encephalopathies. Typically, these variants cause a loss-of-function molecular phenotype whereby γ-aminobutyric acid has reduced inhibitory effectiveness leading to seizures. Drugs that potentiate inhibitory GABAergic activity, such as nitrazepam, phenobarbital or vigabatrin, are expected to compensate for this and thereby reduce seizure frequency. However, vigabatrin, a drug that inhibits γ-aminobutyric acid transaminase to increase tonic γ-aminobutyric acid currents, has mixed success in treating seizures in patients with GABRB3 variants: some patients experience seizure cessation, but there is hypersensitivity in some patients associated with hypotonia, sedation and respiratory suppression. A GABRB3 variant that responds well to vigabatrin involves a truncation variant (p.Arg194*) resulting in a clear loss-of-function. We hypothesized that patients with a hypersensitive response to vigabatrin may exhibit a different γ-aminobutyric acid A receptor phenotype. To test this hypothesis, we evaluated the phenotype of de novo variants in GABRB3 (p.Glu77Lys and p.Thr287Ile) associated with patients who are clinically hypersensitive to vigabatrin. We introduced the GABRB3 p.Glu77Lys and p.Thr287Ile variants into a concatenated synaptic and extrasynaptic γ-aminobutyric acid A receptor construct, to resemble the γ-aminobutyric acid A receptor expression by a patient heterozygous for the GABRB3 variant. The mRNA of these constructs was injected into Xenopus oocytes and activation properties of each receptor measured by two-electrode voltage clamp electrophysiology. Results showed an atypical gain-of-function molecular phenotype in the GABRB3 p.Glu77Lys and p.Thr287Ile variants characterized by increased potency of γ-aminobutyric acid A without change to the estimated maximum open channel probability, deactivation kinetics or absolute currents. Modelling of the activation properties of the receptors indicated that either variant caused increased chloride flux in response to low concentrations of γ-aminobutyric acid that mediate tonic currents. We therefore propose that the hypersensitivity reaction to vigabatrin is a result of GABRB3 variants that exacerbate GABAergic tonic currents and caution is required when prescribing vigabatrin. In contrast, drug strategies increasing tonic currents in loss-of-function variants are likely to be a safe and effective therapy. This study demonstrates that functional genomics can explain beneficial and adverse anti-epileptic drug effects, and propose that vigabatrin should be considered in patients with clear loss-of-function GABRB3 variants.

scholarly journals Increased presence of nuclear DNAJA3 and upregulation of cytosolic STAT1 and of nucleic acid sensors trigger innate immunity in the ClpP-null mouse

Neurogenetics ◽  
2021 ◽  
Author(s):  
Antonia Maletzko ◽  
Jana Key ◽  
Ilka Wittig ◽  
Suzana Gispert ◽  
Gabriele Koepf ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Nucleic Acid ◽  
Inflammatory Responses ◽  
Subcellular Fractionation ◽  
Inflammatory Factors ◽  
Null Mouse ◽  
Loss Of Function ◽  
Response Factors ◽  
Perrault Syndrome ◽  
Acid Sensors

AbstractMitochondrial dysfunction may activate innate immunity, e.g. upon abnormal handling of mitochondrial DNA in TFAM mutants or in altered mitophagy. Recent reports showed that also deletion of mitochondrial matrix peptidase ClpP in mice triggers transcriptional upregulation of inflammatory factors. Here, we studied ClpP-null mouse brain at two ages and mouse embryonal fibroblasts, to identify which signaling pathways are responsible, employing mass spectrometry, subcellular fractionation, immunoblots, and reverse transcriptase polymerase chain reaction. Several mitochondrial unfolded protein response factors showed accumulation and altered migration in blue-native gels, prominently the co-chaperone DNAJA3. Its mitochondrial dysregulation increased also its extra-mitochondrial abundance in the nucleus, a relevant observation given that DNAJA3 modulates innate immunity. Similar observations were made for STAT1, a putative DNAJA3 interactor. Elevated expression was observed not only for the transcription factors Stat1/2, but also for two interferon-stimulated genes (Ifi44, Gbp3). Inflammatory responses were strongest for the RLR pattern recognition receptors (Ddx58, Ifih1, Oasl2, Trim25) and several cytosolic nucleic acid sensors (Ifit1, Ifit3, Oas1b, Ifi204, Mnda). The consistent dysregulation of these factors from an early age might influence also human Perrault syndrome, where ClpP loss-of-function leads to early infertility and deafness, with subsequent widespread neurodegeneration.

scholarly journals The Multifaceted Roles of MicroRNAs in Cystic Fibrosis

Diagnostics ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1102
Author(s):  
Fatima Domenica Elisa De Palma ◽  
Valeria Raia ◽  
Guido Kroemer ◽  
Maria Chiara Maiuri
Keyword(s):  
Cystic Fibrosis ◽  
Respiratory Infections ◽  
Current Knowledge ◽  
Pancreatic Insufficiency ◽  
Clinical Manifestations ◽  
Predictive Biomarkers ◽  
Loss Of Function ◽  
Gene Encoding ◽  
Multisystemic Disease

Cystic fibrosis (CF) is a lifelong disorder affecting 1 in 3500 live births worldwide. It is a monogenetic autosomal recessive disease caused by loss-of-function mutations in the gene encoding the chloride channel cystic fibrosis transmembrane conductance regulator (CFTR), the impairment of which leads to ionic disequilibria in exocrine organs. This translates into a chronic multisystemic disease characterized by airway obstruction, respiratory infections, and pancreatic insufficiency as well as hepatobiliary and gastrointestinal dysfunction. Molecular characterization of the mutational heterogeneity of CFTR (affected by more than 2000 variants) improved the understanding and management of CF. However, these CFTR variants are linked to different clinical manifestations and phenotypes, and they affect response to treatments. Expanding evidence suggests that multisystemic disease affects CF pathology via impairing either CFTR or proteins regulated by CFTR. Thus, altering the expression of miRNAs in vivo could constitute an appealing strategy for developing new CF therapies. In this review, we will first describe the pathophysiology and clinical management of CF. Then, we will summarize the current knowledge on altered miRNAs in CF patients, with a focus on the miRNAs involved in the deregulation of CFTR and in the modulation of inflammation. We will highlight recent findings on the potential utility of measuring circulating miRNAs in CF as diagnostic, prognostic, and predictive biomarkers. Finally, we will provide an overview on potential miRNA-based therapeutic approaches.

scholarly journals Genomic Variation in IbA10G2 and Other Patient-Derived Cryptosporidium hominis Subtypes

2016 ◽  
Vol 55 (3) ◽  
pp. 844-858 ◽  
Author(s):  
Per Sikora ◽  
Sofia Andersson ◽  
Jadwiga Winiecka-Krusnell ◽  
Björn Hallström ◽  
Cecilia Alsmark ◽  
...  
Keyword(s):  
Parasite Burden ◽  
Genomic Variation ◽  
Loss Of Function ◽  
Oocyst Wall ◽  
Gene Encoding ◽  
Cryptosporidium Hominis ◽  
Content Type ◽  
Successful Isolation ◽  
Target Dna ◽  
Stool Samples

ABSTRACTIn order to improve genotyping and epidemiological analysis ofCryptosporidiumspp., genomic data need to be generated directly from a broad range of clinical specimens. Utilizing a robust method that we developed for the purification and generation of amplified target DNA, we present its application for the successful isolation and whole-genome sequencing of 14 differentCryptosporidium hominispatient specimens. Six isolates of subtype IbA10G2 were analyzed together with a single representative each of 8 other subtypes: IaA20R3, IaA23R3, IbA9G3, IbA13G3, IdA14, IeA11G3T3, IfA12G1, and IkA18G1. Parasite burden was measured over a range of more than 2 orders of magnitude for all samples, while the genomes were sequenced to mean depths of between 17× and 490× coverage. Sequence homology-based functional annotation identified several genes of interest, including the gene encodingCryptosporidiumoocyst wall protein 9 (COWP9), which presented a predicted loss-of-function mutation in all the sequence subtypes, except for that seen with IbA10G2, which has a sequence identical to theCryptosporidium parvumreference Iowa II sequence. Furthermore, phylogenetic analysis showed that all the IbA10G2 genomes form a monophyletic clade in theC. hoministree as expected and yet display some heterogeneity within the IbA10G2 subtype. The current report validates the aforementioned method for isolating and sequencingCryptosporidiumdirectly from clinical stool samples. In addition, the analysis demonstrates the potential in mining data generated from sequencing multiple whole genomes ofCryptosporidiumfrom human fecal samples, while alluding to the potential for a higher degree of genotyping withinCryptosporidiumepidemiology.

scholarly journals Functional characterization of a loss-of-function mutant I324M of arginine vasopressin receptor 2 in X-linked nephrogenic diabetes insipidus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lixia Wang ◽  
Weihong Guo ◽  
Chunyun Fang ◽  
Wenli Feng ◽  
Yumeng Huang ◽  
...  
Keyword(s):  
Diabetes Insipidus ◽  
Arginine Vasopressin ◽  
Nephrogenic Diabetes Insipidus ◽  
Functional Characterization ◽  
Gene Mutations ◽  
Biochemical Properties ◽  
Vasopressin Receptor ◽  
Inherited Disease ◽  
Loss Of Function ◽  
Gene Encoding

AbstractX-linked nephrogenic diabetes insipidus (X-linked NDI) is a rare inherited disease mainly caused by lost-of-function mutations in human AVPR2 gene encoding arginine vasopressin receptor 2 (V2R). Our focus of the current study is on exploration of the functional and biochemical properties of Ile324Met (I324M) mutation identified in a pedigree showing as typical recessive X-linked NDI. We demonstrated that I324M mutation interfered with the conformation of complex glycosylation of V2R. Moreover, almost all of the I324M-V2R failed to express on the cell surface due to being captured by the endoplasmic reticulum control system. We further examined the signaling activity of DDAVP-medicated cAMP and ERK1/2 pathways and the results revealed that the mutant receptor lost the ability in response to DDAVP stimulation contributed to the failure of accumulation of cAMP and phosphorylated ERK1/2. Based on the characteristics of molecular defects of I324M mutant, we selected two reagents (SR49059 and alvespimycin) to determine whether the functions of I324M-V2R can be restored and we found that both compounds can significantly “rescue” I324M mutation. Our findings may provide further insights for understanding the pathogenic mechanism of AVPR2 gene mutations and may offer some implications on development of promising treatments for patients with X-linked NDI.

WED 202 Lamb-shaffer syndrome: importance of snp array in diagnosing neurodevelopmental syndromes

2018 ◽  
Vol 89 (10) ◽  
pp. A29.4-A30 ◽  
Author(s):  
Ela M Akay ◽  
Ian S Schofield ◽  
Ming H Lai ◽  
Rhys H Thomas
Keyword(s):  
Intellectual Disability ◽  
Language Impairment ◽  
Cervical Vertebrae ◽  
Snp Array ◽  
Global Developmental Delay ◽  
Prior History ◽  
Loss Of Function ◽  
Mild Intellectual Disability ◽  
Gene Encoding ◽  
Original Cohort

We describe the seizure phenotype of a 26 year old lady who presented with a probable photic-induced convulsion on a background of mild intellectual disability, facial dysmorphia, fused cervical vertebrae and ventricular septal defect. There was no prior history of seizures.Routine EEG was polyrhythmic with a prominent photoparoxysmal response at 14 Hz and 40 Hz. CT head was normal. A SNP array demonstrated a rare 51 kb deletion at 12 p12.1 which disrupts the SOX5 gene.SOX5 is a developmentally important gene encoding a transcription factor that plays a role in multiple developmental pathways including of the nervous system. Loss of function of this gene is associated with Lamb-Shaffer syndrome, first characterised in 2012 with global developmental delay, intellectual disability, mild dysmorphic facies, language impairment and variable skeletal abnormalities.3 of the original cohort of 16 patients described experienced seizures and the nature of their epilepsy was not further defined. Only a further 7 cases have been reported to date, none of whom experienced seizures. Our case helps to broaden the phenotype of Lamb-Shaffer syndrome, highlights the importance of looking for copy number variation and poses questions regarding the neurobiology of photo-sensitivity.

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