GSE202275
Slowing prion disease via M1 muscarinic receptors is associated with reduced neuroinflammation and down-regulation of neurodegenerative disease markers
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. Overall design: Gene expression profiles of hippocampi from each group (control + vehicle, control + VU846, prion + vehicle and prion + VU846) were generated by RNAseq using NextSeq500 instrument (Illumina) sequencer.