Acetylcholine Receptor Subunits Research Articles

Acetylcholine receptor subunit expression in Huntington's disease mouse muscle

Huntington's disease (HD) causes neurological impairments, as well as muscle dysfunction, including smaller neuromuscular junctions (NMJs). This study assessed the expression levels of the subunits of the nicotinic acetylcholine receptor (nAChR) in muscles of the R6/2 mouse model of HD. Based on our previous findings of reduced NMJ size in R6/2 mice, it was hypothesized that muscles from R6/2 mice would also show an altered expression pattern of nAChR subunits compared to wild-type (WT) mice. Therefore, the mRNA levels of nAChR subunits were quantified in R6/2 and WT mouse muscles using qRT-PCR. Denervated muscles from WT mice served as positive controls for alterations in nAChR expression. Although some changes in nAChR subunit expression occurred in R6/2 muscles, the expression levels closely resembled WT. However, the expression of nAChR subunit-ε (Chrne) was significantly decreased in R6/2 muscles relative to WT. This study demonstrates that only minor changes in nAChR subunit expression occurs in R6/2 mouse muscles and that reduction in Chrne expression may be related to a reduction in NMJ size in R6/mice.

Mechanosensation: Alpha-7 nAChR transduces sound signals in earless C. elegans

How do organisms without specialized auditory systems perceive and transduce sound? In this issue of Neuron, Iliff etal. (2021) investigate the functional mechanism of airborne sound sensation in Caenorhabditis elegans and highlight the crucial role of alpha-7 nicotinic acetylcholine receptor subunits in mechanotransduction.

Nicotinic Acetylcholine Receptor Subunit α7 Mediates Cigarette Smoke-Induced PD-L1 Expression in Human Bronchial Epithelial Cells.

Simple SummaryLung cancer is strongly associated with tobacco smoking. Nicotine in tobacco smoke can be transformed into a carcinogen after in vivo metabolism. However, the mechanism of how nicotine metabolites modulate a pro-tumorigenic microenvironment remains largely unknown. We have explored the effects of nicotine stimulation on nicotinic acetylcholine receptor subunit alpha 7 (nAChRα7)-mediated PD-L1 expression in human bronchial epithelial cells (HBECs). PD-L1 is an important protein contributing to cancer immune escape and is currently the key biomarker for lung cancer immunotherapy. Here, we found that the nicotine metabolite NNK can induce PD-L1 expression in HBECs by acting through the nicotine receptor nAChRα7. This study has a direct impact on the understanding of smoking-related changes in bronchial epithelial cells and potential immune escape in smoking-related carcinogenesis and has immuno-therapeutic implications via PD-L1 in lung cancer. Further studies are warranted to examine the upstream inhibition of PD-L1-related pathways, which could be mediated through nicotinic acetylcholine receptors in smokers, and may ultimately aid in the prevention and treatment of lung cancer.Tobacco smoking is the top risk factor for lung cancer development. Nicotine in cigarettes can induce addiction, and its derivatives become potent carcinogens after metabolic activation and activate oncogenic signaling in lung epithelial cells through their expressed nicotinic acetylcholine receptors (nAChRs). However, the effects of smoking on the tumor immune microenvironment are under investigation. In the current study, we investigated whether nicotine activation of nicotinic acetylcholine receptor subunit α7 (nAChRα7, CHRNA7) would induce PD-L1 expression in lung epithelial cells. The expression levels of nAChRα7 and PD-L1 in eight human bronchial epithelial cell (HBEC) lines were measured after treatment with cigarette smoke extract (CSE) or nicotine derivatives. The results showed that PD-L1 expression levels increased in HBECs after exposure to CSE or nicotine derivatives. This induction of PD-L1 expression could be diminished by treatment with CHRNA7 small-interfering RNA, and the relevant signaling was mediated via STAT3 phosphorylation and NRF2 expression. In summary, this study demonstrated that the well-known nicotine derivative-activated nAChRα7 could induce STAT3/NRF2 pathways and subsequently promote PD-L1 expression in normal lung epithelial cells. This information provides mechanistic insight into cigarette smoke-induced immune evasion in lung epithelial cells.

No Correlation between Fagerstrom Test for Nicotine Dependence Scores to Lipopolysaccharide Marker in Thai Smokers

<span>Cigarette smoking is a combination of thousands of synthetic compounds that contribute straightforwardly or by implication to the addiction of cigarette smoking with inflammation, although a lot more may exist. Genome-wide association studies (GWAS) have unequivocally shown that variety in neuronal nicotinic acetylcholine receptor subunit α5 (CHRNA5) and in cytochrome P450 2A6 (CYP2A6) anticipated smoking substantialness, later period of smoking discontinuance.</span><span>The relationship between the Fagerstrom Test for Nicotine Dependence and the Lipopolysaccharide marker in Thai smokers was proposed in this study.</span><span>We </span><span>investigated </span><span>fourteen Thai smokers in Mahasarakham province who scored 4 or higher on the Fagerstrom Test for Nicotine Dependence. We provided them surveys about their personal information, administered the Fagerstrom Test for Nicotine Dependence, and continued the Lipopolysaccharide marker blood tests. The value of R in Pearson connection was 0.4438. Although it found a positive correlation, the relationship between Fagerstrom Test for Nicotine Dependence and Lipopolysaccharide level was weak due to no correlation. In addition, the value of R2, the coefficient of determination, was 0.197 (<em>p</em>=0.1119). Further studies are needed to investigate more the relationship between smoking and inflammation.</span>

Paraneoplastic autoimmune autonomic ganglionopathy as a debut of a bladder urothelial carcinoma: A case report

Autoimmune autonomic ganglionopathy (AAG) is a rare immune-mediated disorder associated with anti-α3 subunit of the ganglionic-type nicotinic acetylcholine receptor (anti-gAChRα3) antibodies, which bind to the acetylcholine-receptor in autonomic ganglia (parasympathetic and sympathetic), leading to autonomic failure. This disorder is mostly associated with viral infections, but it can also be associated with systemic malignancies. Here, we report the first case of a paraneoplastic autonomic ganglionopathy as a debut of a bladder urothelial carcinoma.

Mechanisms underlying cognitive impairment induced by prenatal nicotine exposure: a literature review.

Human and animal studies have conclusively shown that prenatal nicotine exposure alters fetal brain development and causes persistent impairment in the cognitive function of offspring. However, the mechanisms underlying the effect of prenatal nicotine exposure on cognitive function in offspring are still unclear. The objective of this review is to discuss the published studies on the mechanisms underlying the effects of prenatal nicotine exposure on cognitive impairment and discuss the potential mechanisms of action. The findings of the reviewed studies show that the main mechanisms involved are alteration in the composition of nicotinic acetylcholine receptor subunits, increase in surface expression of the glutamate receptor subunit GluR2, a reduction in neurogenesis, alteration of Akt and ERK1/2 activity, and mitochondrial dysfunction in the hippocampus and cortex. These pathways could shed light on future molecular markers and therapeutic targets for the prevention and treatment of cognitive dysfunction induced by prenatal nicotine exposure.

Association Study of Polymorphisms in Neuronal Nicotinic Acetylcholine Receptor Subunit Genes With Schizophrenia in the Han Chinese Population.

ObjectiveTo investigate the relation between nicotinic acetylcholine receptor subunit (nAChR) genes and schizophrenia, and the relation between tag single nucleotide polymorphism (rs1317286, rs1044396, rs6494212, rs16969968, and rs684513) and schizophrenia in Han Chinese people. MethodsThe protein-protein interaction (PPI) network among nAChR protein and 350 proteins encoded by schizophrenia-related susceptibility genes was constructed through the String database to explore whether nAChR genes were associated with schizophrenia in these known databases. Then, five single nucleotide polymorphisms (SNPs) of CHRNA3 (rs1317286), CHRNA4 (rs1044396), CHRNA7 (rs6494212), and CHRNA5 (rs16969968, rs684513) were analyzed in a sample of 1,035 schizophrenic patients and 816 healthy controls. The interaction between the markers was analyzed using multifactor dimensionality reduction (MDR) software. Power analysis was performed using the Quanto program. ResultsThere are no significant differences in genotype or allele distribution were identified between the patients and controls (p>0.05). The haplotypes constructed by four markers rs1317286, rs6494212, rs16969968, and rs684513 were not associated with schizophrenia either. However, a significant association between models made of rs1317286, rs1044396, rs6494212, and rs684513 and schizophrenia was revealed in interaction analysis (p<0.05). ConclusionThe nAChR protein may have effects on the development of schizophrenia through the interaction with proteins encoded by schizophrenia-related susceptibility genes, but no relation was found between selected polymorphisms and schizophrenia in the collected Han Chinese people. However, interaction analysis suggested four-SNP model has an important effect on schizophrenia.

Detection of differential selection pressure and functional-specific sites in subunits of vertebrate neuronal nicotinic acetylcholine receptors

The nicotinic acetylcholine receptors (nAChR) are made of subunits evolved from a common ancestor. Despite the similarity in their sequences and structures, the properties of these subunits vary significantly. Thus, identifying the evolution features and function-related sites specific to each subunit is essential for understanding the characteristics of the subunits and the receptors assembled by them. In this study, we examined the sequence features of the nine neuronal nAChRs subunits from representative vertebrate species. Analysis revealed that all the subunits were subject to strong purifying selection in evolution, and each was under a unique pattern of selection pressures. At the same time, the functional constraints were not uniform within each subunit, with different domains in the molecule being subject to different selection pressures. We also detected potential positive selection events in the subunits or subunit clusters, and identified the sites might be associated with the function specificity of each subunit. Furthermore, positive selection at some domains might contribute to the diversity of subunit function; for example, the β9 strand might be related to the agonist specificity of α subunit in heteromeric receptor and β4-β5 linker could be involved in Ca2+ permeability. Subunits α7, α4 and β2 subunits possess a strong adaptability in vertebrates. Our results highlighted the importance of tracking functional differentiation in protein sequence underlying functional properties of nAChRs. In summary, our work may provide clues on understanding the diversity and the function specificity of the nAChR subunits, as well as the receptors co-assembled by them. Communicated by Ramaswamy H. Sarma

Mode of Action of Neonicotinoid Insecticides Imidacloprid and Thiacloprid to the Cockroach Pameα7 Nicotinic Acetylcholine Receptor.

The functional expression of the cockroach Pameα7 nicotinic acetylcholine receptor subunit has been previously studied, and was found to be able to form a homomeric receptor when expressed in Xenopus laevis oocytes. In this study, we found that the neonicotinoid insecticide imidacloprid is unable to activate the cockroach Pameα7 receptor, although thiacloprid induces low inward currents, suggesting that it is a partial agonist. In addition, the co-application or 5 min pretreatment with 10 µM imidacloprid increased nicotine current amplitudes, while the co-application or 5 min pretreatment with 10 µM thiacloprid decreased nicotine-evoked current amplitudes by 54% and 28%, respectively. This suggesting that these two representatives of neonicotinoid insecticides bind differently to the cockroach Pameα7 receptor. Interestingly, the docking models demonstrate that the orientation and interactions of the two insecticides in the cockroach Pameα7 nAChR binding pocket are very similar. Electrophysiological results have provided evidence to suggest that imidacloprid and thiacloprid could act as modulators of the cockroach Pameα7 receptors.

Five New Cases of Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome (MMIHS), with One Case Showing a Novel Mutation

Background Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a lethal congenital disorder characterized by a large, non-obstructed bladder, microcolon, and lack of proper peristalsis. Materials and methods Five cases of MMIHS were identified, confirmed histologically and were predominantly female (F:M, 4:1). DNA sequencing was also performed. Results Four cases showed mutations in the α3 and β4 nicotinic acetylcholine receptor (ηAChR) subunits (CHRNA3 and CHRNB4, respectively) on chromosome 15q24. The 5th case had a delayed clinical presentation of intussusception at 11 months and showed a novel missense mutation in ATP2B4 on Chromosome 1q32. Conclusion The first four patients showed a previously identified mutation. The 5th patient shows a novel mutation in ATP2B4. This novel gene was associated with a less severe presentation and increases success of multiorgan transplant than the other four patients. This highlights how identifying various mutations may impact prognosis and clinical treatment plans for MMIHS patients.

Altered neuronal physiology, development, and function associated with a common chromosome 15 duplication involving CHRNA7

BackgroundCopy number variants (CNVs) linked to genes involved in nervous system development or function are often associated with neuropsychiatric disease. While CNVs involving deletions generally cause severe and highly penetrant patient phenotypes, CNVs leading to duplications tend instead to exhibit widely variable and less penetrant phenotypic expressivity among affected individuals. CNVs located on chromosome 15q13.3 affecting the alpha-7 nicotinic acetylcholine receptor subunit (CHRNA7) gene contribute to multiple neuropsychiatric disorders with highly variable penetrance. However, the basis of such differential penetrance remains uncharacterized. Here, we generated induced pluripotent stem cell (iPSC) models from first-degree relatives with a 15q13.3 duplication and analyzed their cellular phenotypes to uncover a basis for the dissimilar phenotypic expressivity.ResultsThe first-degree relatives studied included a boy with autism and emotional dysregulation (the affected proband-AP) and his clinically unaffected mother (UM), with comparison to unrelated control models lacking this duplication. Potential contributors to neuropsychiatric impairment were modeled in iPSC-derived cortical excitatory and inhibitory neurons. The AP-derived model uniquely exhibited disruptions of cellular physiology and neurodevelopment not observed in either the UM or unrelated controls. These included enhanced neural progenitor proliferation but impaired neuronal differentiation, maturation, and migration, and increased endoplasmic reticulum (ER) stress. Both the neuronal migration deficit and elevated ER stress could be selectively rescued by different pharmacologic agents. Neuronal gene expression was also dysregulated in the AP, including reduced expression of genes related to behavior, psychological disorders, neuritogenesis, neuronal migration, and Wnt, axonal guidance, and GABA receptor signaling. The UM model instead exhibited upregulated expression of genes in many of these same pathways, suggesting that molecular compensation could have contributed to the lack of neurodevelopmental phenotypes in this model. However, both AP- and UM-derived neurons exhibited shared alterations of neuronal function, including increased action potential firing and elevated cholinergic activity, consistent with increased homomeric CHRNA7 channel activity.ConclusionsThese data define both diagnosis-associated cellular phenotypes and shared functional anomalies related to CHRNA7 duplication that may contribute to variable phenotypic penetrance in individuals with 15q13.3 duplication. The capacity for pharmacological agents to rescue some neurodevelopmental anomalies associated with diagnosis suggests avenues for intervention for carriers of this duplication and other CNVs that cause related disorders.

Nicotine Patch Improved Autosomal Dominant Sleep-Related Hypermotor Epilepsy

Autosomal dominant sleep-related hypermotor epilepsy (ADSHE) is a genetic focal epilepsy associated with mutations in the nicotinic acetylcholine receptor. Mutations in two major nicotinic acetylcholine receptor subunit genes, CHRNA4 and CHRNB2, are commonly associated with ADSHE.1Saberi B. Tehrani B.S. Pore-forming M2 domains of CHRNA4 and CHRNB2 mutations in autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) phenotype.Am J Biomed Sci Res. 2019; 1: 222-223Crossref Google Scholar In up to one-third of patients with ADSHE, seizures are refractory to antiseizure medications. Here, we report complete seizure freedom with transdermal nicotine in two pediatric patients from the same family with medically refractory ADSHE. Both patients, who are siblings, presented with exclusively nocturnal focal seizures in childhood, at ages seven years (Patient 1) and 4.5 years (Patient 2). Elelctroencephalographies (EEGs) demonstrated focal electroclinical seizures with hypermotor features and interictal epileptiform discharges in sleep (Fig A and B). Genetic testing revealed a heterozygous missense mutation in CHRNA4 (c.851C>T P.Ser284Leu), which has been described as a common pathogenic gain-of-function mutation in ADSHE. Patient 2 was also diagnosed with an autism spectrum disorder. Both patients had a high nightly seizure burden with minimal improvement on numerous antiseizure medications. A trial of low-dose (7 mg/24 hour) nicotine patch was initiated at ages 16 years (Patient 1) and 14 years (Patient 2). Clinical seizures stopped in both the first night the patch was applied. Follow-up overnight EEGs confirmed seizure freedom and showed normalization or near-normalization of their interictal EEGs (Fig C). Both patients have experienced sustained seizure freedom for over 18 months with nicotine patch 7 mg/24 hour in addition to oxcarbazepine. Transdermal nicotine has been reported to provide marked seizure improvement in a subset of patients with ADSHE.2Fox J. Thodeson D.M. Dolce A.M. Nicotine: a targeted therapy for epilepsy due to nAChR gene variants.J Child Neurol. 2020; 36: 371-377Crossref PubMed Scopus (3) Google Scholar,3Lossius K. de Saint Martin A. Myren-Svelstad S. et al.Remarkable effect of transdermal nicotine in children with CHRNA4-related autosomal dominant sleep-related hypermotor epilepsy.Epilepsy Behav. 2020; 105: 106944Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar The siblings reported here have the same CHRNA4 mutation as a 19-year-old patient who had considerable seizure improvement, although not complete resolution, with transdermal nicotine at a higher dose of 14 mg/24 hour.2Fox J. Thodeson D.M. Dolce A.M. Nicotine: a targeted therapy for epilepsy due to nAChR gene variants.J Child Neurol. 2020; 36: 371-377Crossref PubMed Scopus (3) Google Scholar Lossius et al. described striking improvement in seizures and neuropsychological test performance in three six- to 10-year-old children with a different CHRNA4 mutation (c.839C>T P.Ser280Phe) who were treated with 3.5 to 7 mg/24 hour nicotine.3Lossius K. de Saint Martin A. Myren-Svelstad S. et al.Remarkable effect of transdermal nicotine in children with CHRNA4-related autosomal dominant sleep-related hypermotor epilepsy.Epilepsy Behav. 2020; 105: 106944Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar With different patient characteristics, age as well as specific mutation might contribute to the efficacy of nicotine patches in controlling seizure activity. Christensen et al. discussed how nicotine increases neuronal firing of cholinergic cells in younger animals, which in turn affects the action potential shape and afterhyperpolarization.4Christensen M.H. Ishibashi M. Nielsen M.L. Leonard C.S. Kohlmeier K.A. Age-related changes in nicotine response of cholinergic and non-cholinergic laterodorsal tegmental neurons: implications for the heightened adolescent susceptibility to nicotine addiction.Neuropharmacology. 2014; 85: 263-283Crossref PubMed Scopus (15) Google Scholar Nicotine has been found to cause age-dependent changes in gene expression in adolescent female rat brains.5Polesskaya O.O. Fryxell K.J. Merchant A.D. et al.Nicotine causes age-dependent changes in gene expression in the adolescent female rat brain.Neurotoxicol Teratol. 2007; 29: 126-140Crossref PubMed Scopus (33) Google Scholar In adolescence, GABAergic signaling in the prefrontal cortex, an important brain region associated with ADSHE, is still developing.6Caballero A. Tseng K.Y. GABAergic function as a limiting factor for prefrontal maturation during adolescence.Trends Neurosci. 2016; 39: 441-448Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar Therefore, age might be an important factor when determining whether nicotine patch treatment may be beneficial for patients with ADSHE, with regard to both seizure improvement and neuropsychologic outcomes. A limitation of our report is that our patients are from the same family and therefore may possess unique characteristics that influenced their dramatic response to transdermal nicotine. This possibility might prevent generalization of our results to all patients with same mutation in CHRNA4. Nevertheless, the two siblings reported here add to the small number of pediatric reports documenting the successful use of nicotine patches in ADSHE. Future research is needed to establish whether the nicotine patch could become an adjunct or first-line treatment in a subset of pediatric patients with ADSHE. The authors wish to thank all the patients, family members, and staff members who participated in the study.

Loss of the Dβ1 nicotinic acetylcholine receptor subunit disrupts bursicon-driven wing expansion and diminishes adult viability in Drosophila melanogaster.

Cholinergic signaling dominates the insect central nervous system, contributing to numerous fundamental pathways and behavioral circuits. However, we are only just beginning to uncover the diverse roles different cholinergic receptors may play. Historically, insect nicotinic acetylcholine receptors have received attention due to several subunits being key insecticide targets. More recently, there has been a focus on teasing apart the roles of these receptors, and their constituent subunits, in native signaling pathways. In this study, we use CRISPR-Cas9 genome editing to generate germline and somatic deletions of the Dβ1 nicotinic acetylcholine receptor subunit and investigate the consequences of loss of function in Drosophila melanogaster. Severe impacts on movement, male courtship, longevity, and wing expansion were found. Loss of Dβ1 was also associated with a reduction in transcript levels for the wing expansion hormone bursicon. Neuron-specific somatic deletion of Dβ1 in bursicon-producing neurons (CCAP-GAL4) was sufficient to disrupt wing expansion. Furthermore, CCAP-GAL4-specific expression of Dβ1 in a germline deletion background was sufficient to rescue the wing phenotype, pinpointing CCAP neurons as the neuronal subset requiring Dβ1 for the wing expansion pathway. Dβ1 is a known target of multiple commercially important insecticides, and the fitness costs exposed here explain why field-isolated target-site resistance has only been reported for amino acid replacements and not loss of function. This work reveals the importance of Dβ1-containing nicotinic acetylcholine receptors in CCAP neurons for robust bursicon-driven wing expansion.

Inhibition of the neuromuscular acetylcholine receptor with atracurium activates FOXO/DAF-16-induced longevity.

Transcriptome‐based drug screening is emerging as a powerful tool to identify geroprotective compounds to intervene in age‐related disease. We hypothesized that, by mimicking the transcriptional signature of the highly conserved longevity intervention of FOXO3 (daf‐16 in worms) overexpression, we could identify and repurpose compounds with similar downstream effects to increase longevity. Our in silico screen, utilizing the LINCS transcriptome database of genetic and compound interventions, identified several FDA‐approved compounds that activate FOXO downstream targets in mammalian cells. These included the neuromuscular blocker atracurium, which also robustly extends both lifespan and healthspan in Caenorhabditis elegans. This longevity is dependent on both daf‐16 signaling and inhibition of the neuromuscular acetylcholine receptor subunit unc‐38. We found unc‐38 RNAi to improve healthspan, lifespan, and stimulate DAF‐16 nuclear localization, similar to atracurium treatment. Finally, using RNA‐seq transcriptomics, we identify atracurium activation of DAF‐16 downstream effectors. Together, these data demonstrate the capacity to mimic genetic lifespan interventions with drugs, and in doing so, reveal that the neuromuscular acetylcholine receptor regulates the highly conserved FOXO/DAF‐16 longevity pathway.

The Intergenerational Transmission of Developmental Nicotine Exposure-Induced Neurodevelopmental Disorder-Like Phenotypes is Modulated by the Chrna5 D397N Polymorphism in Adolescent Mice.

Maternal tobacco smoking during pregnancy constitutes developmental nicotine exposure (DNE) and is associated with nicotine dependence and neurodevelopmental disorders in both children and grandchildren as well as animal models thereof. Genetic variants such as the CHRNA5 single nucleotide polymorphism (SNP) rs16969968, which leads to an aspartic acid to asparagine substitution at amino acid position 398 (D398N) in the alpha-5 nicotinic acetylcholine receptor subunit, can also confer risk for nicotine dependence and neurodevelopmental disorders in the absence of DNE. However, the degrees to which, the consequences of maternal smoking on offspring outcomes are influenced by genetic variants and interactions therewith are not well understood. Addressing this void in the literature, the present study utilizes a DNE mouse model engineered to possess the equivalent of the human D398N SNP in CHRNA5 (D397N SNP in mice) to assess how the N397 risk allele impacts the induction and intergenerational transmission of a range of neurodevelopmental disorder-related behavioral phenotypes in first- and second-generation DNE offspring. Results reveal that offspring possessing the N397 variant in the absence of DNE as well as DNE offspring and grand offspring possessing theD397 variant exhibit analogous neurodevelopmental disorder-like phenotypes including hyperactivity, risk-taking behaviors, aberrant rhythmicity of activity, and enhanced nicotine consumption. DNE amplified these behavioral anomalies in first-generation N397 progeny, but the severity of DNE-evoked behavioral perturbations did not significantly differ between first-generation D397 and N397 DNE mice for any measure. Remarkably, the behavioral profiles of second-generation N397 DNE progeny closely resembled DNE-naive D397 mice, suggesting that the N397 variant may protect against the intergenerational transmission of DNE-induced neurodevelopmental disorder-like behaviors.

Chr15q25 Genetic Variant rs16969968 Alters Cell Differentiation in Respiratory Epithelia.

The gene cluster region, CHRNA3/CHRNA5/CHRNB4, encoding for nicotinic acetylcholine receptor (nAChR) subunits, contains several genetic variants linked to nicotine addiction and brain disorders. The CHRNA5 single-nucleotide polymorphism (SNP) rs16969968 is strongly associated with nicotine dependence and lung diseases. Using immunostaining studies on tissue sections and air-liquid interface airway epithelial cell cultures, in situ hybridisation, transcriptomic and cytokines detection, we analysed rs16969968 contribution to respiratory airway epithelial remodelling and modulation of inflammation. We provide cellular and molecular analyses which support the genetic association of this polymorphism with impaired ciliogenesis and the altered production of inflammatory mediators. This suggests its role in lung disease development.

Pharmacokinetics and Molecular Modeling Indicate nAChRα4-Derived Peptide HAEE Goes through the Blood-Brain Barrier.

One of the treatment strategies for Alzheimer’s disease (AD) is based on the use of pharmacological agents capable of binding to beta-amyloid (Aβ) and blocking its aggregation in the brain. Previously, we found that intravenous administration of the synthetic tetrapeptide Acetyl-His-Ala-Glu-Glu-Amide (HAEE), which is an analogue of the 35–38 region of the α4 subunit of α4β2 nicotinic acetylcholine receptor and specifically binds to the 11–14 site of Aβ, reduced the development of cerebral amyloidogenesis in a mouse model of AD. In the current study on three types of laboratory animals, we determined the biodistribution and tissue localization patterns of HAEE peptide after single intravenous bolus administration. The pharmacokinetic parameters of HAEE were established using uniformly tritium-labeled HAEE. Pharmacokinetic data provided evidence that HAEE goes through the blood–brain barrier. Based on molecular modeling, a role of LRP1 in receptor-mediated transcytosis of HAEE was proposed. Altogether, the results obtained indicate that the anti-amyloid effect of HAEE, previously found in a mouse model of AD, most likely occurs due to its interaction with Aβ species directly in the brain.

Temporal regulation of nicotinic acetylcholine receptor subunits supports central cholinergic synapse development in Drosophila

The construction and maturation of the postsynaptic apparatus are crucial for synapse and dendrite development. The fundamental mechanisms underlying these processes are most often studied in glutamatergic central synapses in vertebrates. Whether the same principles apply to excitatory cholinergic synapses, such as those found in the insect central nervous system, is not known. To address this question, we investigated a group of projection neurons in the Drosophila larval visual system, the ventral lateral neurons (LNvs), and identified nAchRα1 (Dα1) and nAchRα6 (Dα6) as the main functional nicotinic acetylcholine receptor (nAchR) subunits in the larval LNvs. Using morphological analyses and calcium imaging studies, we demonstrated critical roles of these two subunits in supporting dendrite morphogenesis and synaptic transmission. Furthermore, our RNA sequencing analyses and endogenous tagging approach identified distinct transcriptional controls over the two subunits in the LNvs, which led to the up-regulation of Dα1 and down-regulation of Dα6 during larval development as well as to an activity-dependent suppression of Dα1 Additional functional analyses of synapse formation and dendrite dynamics further revealed a close association between the temporal regulation of individual nAchR subunits and their sequential requirements during the cholinergic synapse maturation. Together, our findings support transcriptional control of nAchR subunits as a core element of developmental and activity-dependent regulation of central cholinergic synapses.

Transcriptome Analysis of Aedes albopictus (Diptera: Culicidae) Larvae Exposed With a Sublethal Dose of Haedoxan A.

Aedes albopictus is the vector of arbovirus diseases including yellow fever, dengue, Zika virus, and chikungunya fever, and it poses an enormous threat to human health worldwide. Previous studies have revealed that haedoxan A (HA), which is an insecticidal sesquilignan from Phryma leptostachya L., is a highly effective natural insecticide for managing mosquitoes and houseflies; however, the mechanisms underlying the response of Ae. albopictus after treatment with sublethal concentrations of HA is not clear. Here, high-throughput sequencing was used to analyze the gene expression changes in Ae. albopictus larvae after treatment with the LC30 of HA. In total, 416 differentially expressed genes (DEGs) were identified, including 328 upregulated genes and 88 downregulated genes. Identification and verification of related DEGs were performed by RT-qPCR. The results showed that two P450 unigenes (CYP4C21 and CYP304A1), one carboxylesterase, and one ABC transporter (ABCG1) were induced by HA, which indicated that these detoxifying enzyme genes might play a major role in the metabolic and detoxification processes of HA. Additionally, acetylcholine receptor subunit ɑ2 (AChRα2), AChRα5, AChRα9, and the glutamate receptor ionotropic kainate 2 (GRIK2) were found to be upregulated in HA-treated larvae, suggesting that HA affected the conduction of action potentials and synaptic transmission by disrupting the function of neural receptors. These results provide a foundation for further elucidating the target of HA and the mechanism of detoxification metabolism in Ae. albopictus.

The Power of Drosophila melanogaster for Modeling Neonicotinoid Effects on Pollinators and Identifying Novel Mechanisms.

Neonicotinoids are the most widely used insecticides in the world and are implicated in the widespread population declines of insects including pollinators. Neonicotinoids target nicotinic acetylcholine receptors which are expressed throughout the insect central nervous system, causing a wide range of sub-lethal effects on non-target insects. Here, we review the potential of the fruit fly Drosophila melanogaster to model the sub-lethal effects of neonicotinoids on pollinators, by utilizing its well-established assays that allow rapid identification and mechanistic characterization of these effects. We compare studies on the effects of neonicotinoids on lethality, reproduction, locomotion, immunity, learning, circadian rhythms and sleep in D. melanogaster and a range of pollinators. We also highlight how the genetic tools available in D. melanogaster, such as GAL4/UAS targeted transgene expression system combined with RNAi lines to any gene in the genome including the different nicotinic acetylcholine receptor subunit genes, are set to elucidate the mechanisms that underlie the sub-lethal effects of these common pesticides. We argue that studying pollinators and D. melanogaster in tandem allows rapid elucidation of mechanisms of action, which translate well from D. melanogaster to pollinators. We focus on the recent identification of novel and important sublethal effects of neonicotinoids on circadian rhythms and sleep. The comparison of effects between D. melanogaster and pollinators and the use of genetic tools to identify mechanisms make a powerful partnership for the future discovery and testing of more specific insecticides.