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Cholinergic Regulation of hnRNPA2/B1 Translation by M1 Muscarinic Receptors.

ABSTRACT: UNLABELLED:Cholinergic vulnerability, characterized by loss of acetylcholine (ACh), is one of the hallmarks of Alzheimer's disease (AD). Previous work has suggested that decreased ACh activity in AD may contribute to pathological changes through global alterations in alternative splicing. This occurs, at least partially, via the regulation of the expression of a critical protein family in RNA processing, heterogeneous nuclear ribonucleoprotein (hnRNP) A/B proteins. These proteins regulate several steps of RNA metabolism, including alternative splicing, RNA trafficking, miRNA export, and gene expression, providing multilevel surveillance in RNA functions. To investigate the mechanism by which cholinergic tone regulates hnRNPA2/B1 expression, we used a combination of genetic mouse models and in vivo and in vitro techniques. Decreasing cholinergic tone reduced levels of hnRNPA2/B1, whereas increasing cholinergic signaling in vivo increased expression of hnRNPA2/B1. This effect was not due to decreased hnRNPA2/B1 mRNA expression, increased aggregation, or degradation of the protein, but rather to decreased mRNA translation by nonsense-mediated decay regulation of translation. Cell culture and knock-out mice experiments demonstrated that M1 muscarinic signaling is critical for cholinergic control of hnRNPA2/B1 protein levels. Our experiments suggest an intricate regulation of hnRNPA2/B1 levels by cholinergic activity that interferes with alternative splicing in targeted neurons mimicking deficits found in AD. SIGNIFICANCE STATEMENT:In Alzheimer's disease, degeneration of basal forebrain cholinergic neurons is an early event. These neurons communicate with target cells and regulate their long-term activity by poorly understood mechanisms. Recently, the splicing factor hnRNPA2/B, which is decreased in Alzheimer's disease, was implicated as a potential mediator of long-term cholinergic regulation. Here, we demonstrate a mechanism by which cholinergic signaling controls the translation of hnRNPA2/B1 mRNA by activation of M1 muscarinic type receptors. Loss of cholinergic activity can have profound effects in target cells by modulating hnRNPA2/B1 levels.

SUBMITTER: Kolisnyk B

PROVIDER: S-EPMC6604881 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Cholinergic Regulation of hnRNPA2/B1 Translation by M1 Muscarinic Receptors.

Kolisnyk Benjamin B Al-Onaizi Mohammed A MA Xu Jason J Parfitt Gustavo M GM Ostapchenko Valeriy G VG Hanin Geula G Soreq Hermona H Prado Marco A M MA Prado Vania F VF

The Journal of neuroscience : the official journal of the Society for Neuroscience 20160601 23

<h4>Unlabelled</h4>Cholinergic vulnerability, characterized by loss of acetylcholine (ACh), is one of the hallmarks of Alzheimer's disease (AD). Previous work has suggested that decreased ACh activity in AD may contribute to pathological changes through global alterations in alternative splicing. This occurs, at least partially, via the regulation of the expression of a critical protein family in RNA processing, heterogeneous nuclear ribonucleoprotein (hnRNP) A/B proteins. These proteins regulat ...[more]

PMID: 27277805

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Project description:UnlabelledOver the last decade, striatal cholinergic interneurons (ChIs) have reemerged as key actors in the pathophysiology of basal-ganglia-related movement disorders. However, the mechanisms involved are still unclear. In this study, we address the role of ChI activity in the expression of parkinsonian-like motor deficits in a unilateral nigrostriatal 6-hydroxydopamine (6-OHDA) lesion model using optogenetic and pharmacological approaches. Dorsal striatal photoinhibition of ChIs in lesioned ChAT(cre/cre) mice expressing halorhodopsin in ChIs reduces akinesia, bradykinesia, and sensorimotor neglect. Muscarinic acetylcholine receptor (mAChR) blockade by scopolamine produces similar anti-parkinsonian effects. To decipher which of the mAChR subtypes provides these beneficial effects, systemic and intrastriatal administration of the selective M1 and M4 mAChR antagonists telenzepine and tropicamide, respectively, were tested in the same model of Parkinson's disease. The two compounds alleviate 6-OHDA lesion-induced motor deficits. Telenzepine produces its beneficial effects by blocking postsynaptic M1 mAChRs expressed on medium spiny neurons (MSNs) at the origin of the indirect striatopallidal and direct striatonigral pathways. The anti-parkinsonian effects of tropicamide were almost completely abolished in mutant lesioned mice that lack M4 mAChRs specifically in dopamine D1-receptor-expressing neurons, suggesting that postsynaptic M4 mAChRs expressed on direct MSNs mediate the antiakinetic action of tropicamide. The present results show that altered cholinergic transmission via M1 and M4 mAChRs of the dorsal striatum plays a pivotal role in the occurrence of motor symptoms in Parkinson's disease.Significance statementThe striatum, where dopaminergic and cholinergic systems interact, is the pivotal structure of basal ganglia involved in pathophysiological changes underlying Parkinson's disease. Here, using optogenetic and pharmacological approaches, we investigated the involvement of striatal cholinergic interneurons (ChIs) and muscarinic receptor subtypes (mAChRs) in the occurrence of a wide range of motor deficits such as akinesia, bradykinesia, motor coordination, and sensorimotor neglect after unilateral nigrostriatal 6-hydroxydopamine lesion in mice. Our results show that photoinhibition of ChIs in the dorsal striatum and pharmacological blockade of muscarinic receptors, specifically postsynaptic M1 and M4 mAChRs, alleviate lesion-induced motor deficits. The present study points to these receptor subtypes as potential targets for the symptomatic treatment of parkinsonian-like motor symptoms.

Project description:Purpose: evaluation of the neuroprotective effects of VU846 compound, a positive allosteric modulator highly specific for the M1 muscarinic receptor, using the Next-generation sequencing (NGS) technology in a context of neurodegeneration induced by prion disease. Methods: Tg37 hemizygous mice at 3 to 4 weeks were inoculated with either the Rocky Mountain Laboratory (RML) scrapie prion brain homogenate, causative of the neurodegeneration, or normal brain homogenate for control purposes. Mice were also daily injected with either the M1 specific positive allosteric modulator VU836 or vehicle. The drug treatment started at 7week post brain homogenate inoculations (wpi) and 11wpi. The hippocampi from 3 mice of each group (control + vehicle, control + VU846, prion + vehicle and prion + VU846) were subject to tot RNA extraction. Raw reads were then converted into Fastq format, mapped to the “mouse-mm10” genome using HISAT2 (Galaxy Version 2.1.0) and processed with the StringTie (Galaxy Version 1.3.3.2) for assembling and quantification. Differential gene expression comparisons were performed with DESeq2 statistical tool (Galaxy Version 2.11.40.2) and data further analysed with two online software suites, Gene Ontology Panther (http://www.pantherdb.org/) and Pathway Studio (www.pathwaystudio.com). Results: we use the bioinformatic tool Pathway Studio (www.pathwaystudio.com) to quantitatively assesses the changes in the transcriptome with gene functions reported in the literature to assign an actication score. Strikingly, up and down regulation of genes changed by prion disease promote neuroinflammation and Alzheimer’s disease (AD) (positive activation scores), whereas the M1R specific positive allosteric modulator VU846 treatment modified the expression of genes to inhibit the neuroinflammatory and neurodegenerative processes directly associated with AD (negative activation score). Among these are genes associated with the complement system, microglia and astrocyte activation. Furthermore, consistent with the notion that neuroinflammatory pathways were activated in prion disease and diminished by VU846, the GO Pathway analysis revealed enrichment of genes in pathways such as the complement cascade and chemokine/cytokine signalling. Conversely, a group of genes that were down-regulated in prion disease were transcribed at significantly higher levels in the prion-effect of animals treated with VU846. These genes were strongly associated with synaptic plasticity, learning and memory, cognition and synaptic transmission by the GO Pathway analysis. Conclusions: These data point to the possibility that specific features of neuroinflammation and disease-adaptation may be directly regulated by M1-receptor activity strongly reinforcing the concept that pharmaceutically targeting M1 muscarinic receptor is neuroprotective and it might lead to the development of new treatments of Alzheimer’s like neurodegenerative diseases.

Dataset Information

Cholinergic Regulation of hnRNPA2/B1 Translation by M1 Muscarinic Receptors.

Publications

Cholinergic Regulation of hnRNPA2/B1 Translation by M1 Muscarinic Receptors.

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