Dataset Information

Single nucleotide polymorphisms of the human M1 muscarinic acetylcholine receptor gene.

ABSTRACT: The gene encoding the human muscarinic receptor, type 1 (CHRM1), was genotyped from 245 samples of the Coriell Collection (Coriell Institute for Medical Research, Camden, NJ). Fifteen single nucleotide polymorphisms (SNPs) were discovered, 9 of which are located in the coding region of the receptor. Of these, 8 represent synonymous SNPs, indicating that CHRM1 is highly conserved in humans. Only a single allele was found to contain a nonsynonymous SNP, which encodes an amino acid change of Cys to Arg at position 417. This may have functional consequences because a C417S point mutation in rat M1 was previously shown to affect receptor binding and coupling. Furthermore, 0 of 4 SNPs within CHRM1 previously deduced from sequencing of the human genome were found in this study despite a prediction that a majority of such inferred SNPs are accurate. The consensus sequence of CHRM1 obtained in our study differs from the deposited reference sequence (AC NM_000738) in 2 adjacent nucleotides, leading to a V173M change, suggesting a sequencing error in the reference sequence. The extraordinary sequence conservation of the CHRM1 gene-coding region was unexpected as M1-knockout mice show only minimal functional impairments.

SUBMITTER: Lucas JL

PROVIDER: S-EPMC2751220 | biostudies-literature | 2001

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Single nucleotide polymorphisms of the human M1 muscarinic acetylcholine receptor gene.

Lucas J L JL DeYoung J A JA Sadee W W

AAPS pharmSci 20010101 4

The gene encoding the human muscarinic receptor, type 1 (CHRM1), was genotyped from 245 samples of the Coriell Collection (Coriell Institute for Medical Research, Camden, NJ). Fifteen single nucleotide polymorphisms (SNPs) were discovered, 9 of which are located in the coding region of the receptor. Of these, 8 represent synonymous SNPs, indicating that CHRM1 is highly conserved in humans. Only a single allele was found to contain a nonsynonymous SNP, which encodes an amino acid change of Cys to ...[more]

PMID: 12049494

Similar Datasets

Project description:Aggregation of amyloid beta and loss of cholinergic innervation in the brain are predominant components of Alzheimer's disease pathology and likely underlie cognitive impairment. Acetylcholinesterase inhibitors are one of the few treatment options for Alzheimer's disease, where levels of available acetylcholine are enhanced to counteract the cholinergic loss. However, these inhibitors show limited clinical efficacy. One potential explanation for this is a concomitant dysregulation of cholinergic receptors themselves as a consequence of the amyloid beta pathology. We tested this hypothesis by examining levels of M1 muscarinic acetylcholine receptors in the temporal cortex from seven Alzheimer's disease and seven non-disease age-matched control brain tissue samples (control: 85 ± 2.63 years old, moderate Alzheimer's disease: 84 ± 2.32 years old, P-value = 0.721; eight female and six male patients). The samples were categorized into two groups: 'control' (Consortium to Establish a Registry for Alzheimer's Disease diagnosis of 'No Alzheimer's disease', and Braak staging pathology of I-II) and 'moderate Alzheimer's disease' (Consortium to Establish a Registry for Alzheimer's Disease diagnosis of 'possible/probable Alzheimer's disease', and Braak staging pathology of IV). We find that in comparison to age-matched controls, there is a loss of M1 muscarinic acetylcholine receptors in moderate Alzheimer's disease tissue (control: 2.17 ± 0.27 arbitrary units, n = 7, Mod-AD: 0.83 ± 0.16 arbitrary units, n = 7, two-tailed t-test, t = 4.248, P = 0.00113). Using a functional rat cortical brain slice model, we find that postsynaptic muscarinic acetylcholine receptor function is dysregulated by aberrant amyloid beta-mediated activation of metabotropic glutamate receptor 5. Crucially, blocking metabotropic glutamate receptor 5 restores muscarinic acetylcholine receptor function and object recognition memory in 5XFAD transgenic mice. This indicates that the amyloid beta-mediated activation of metabotropic glutamate receptor 5 negatively regulates muscarinic acetylcholine receptor and illustrates the importance of muscarinic acetylcholine receptors as a potential disease-modifying target in the moderate pathological stages of Alzheimer's disease.

Project description:This was a first-in-human study of the PET radiotracer 11C-LSN3172176 for the muscarinic acetylcholine receptor subtype M1. The objectives of the study were to determine the appropriate kinetic model to quantify binding of the tracer to M1 receptors, and the reliability of the chosen quantification method. Methods: Six healthy subjects completed the test-retest protocol, and 5 healthy subjects completed the baseline-scopolamine blocking protocol. Multiple modeling methods were applied to calculate total distribution volume (V T) and nondisplaceable binding potential (BP ND) in various brain regions. The reference region was selected from the blocking study. The occupancy plot was applied to compute receptor occupancy by scopolamine and nondisplaceable distribution volume. Results: Tracer uptake was highest in the striatum, followed by neocortical regions and white matter, and lowest in the cerebellum. Regional time-activity curves were fitted well by all models. The 2-tissue-compartment (2TC) model fits were good, but the 2TC parameters often could not be reliably estimated. Because V T correlated well between the 2TC and 1-tissue-compartment (1TC) models after exclusion of unreliable estimates, the 1TC model was chosen as the most appropriate. The cerebellum showed the lowest V T, consistent with preclinical studies showing little to no specific binding in the region. Further, cerebellar V T did not change between baseline and blocking scans, indicating that the cerebellum is a suitable reference region. The simplified reference tissue model (SRTM) slightly underestimated 1TC BP ND, and the simplified reference tissue model 2 (SRTM2) improved BP ND estimation. An 80-min scan was sufficient to quantify V T and BP ND The test-retest study showed excellent absolute test-retest variability for 1TC V T (≤5%) and BP ND (≤10%). In the baseline and blocking studies, occupancy values were lower in the striatum than in nonstriatal regions, as may be attributed to differences in regional acetylcholine concentrations. Conclusion: The 1TC and SRTM2 models are appropriate for quantitative analysis of 11C-LSN3172176 imaging data. 11C-LSN3172176 displayed excellent test-retest reproducibility and is a highly promising ligand to quantify M1 receptors in the human brain.

Dataset Information

Single nucleotide polymorphisms of the human M1 muscarinic acetylcholine receptor gene.

Publications

Single nucleotide polymorphisms of the human M1 muscarinic acetylcholine receptor gene.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure