Project description:Analysis of mouse chondrocytes lacking the microRNA-140. MicroRNAs are genomically encoded small RNAs to regulate the gene expression. miR-140 shows high expression in cartilage. Results provide insight into the molecular mechanisms underlying miR-140 function in chondrocytes. Keywords: Expression profiling by array
Project description:Analysis of mouse chondrocytes lacking the microRNA-140. MicroRNAs are genomically encoded small RNAs to regulate the gene expression. miR-140 shows high expression in cartilage. Results provide insight into the molecular mechanisms underlying miR-140 function in chondrocytes. Keywords: Expression profiling by array DNA microarray analysis was performed using Affymetrix mouse genome 430 2.0 array. RNA samples collected from cultured rib chondrocytes of wild-type and miR-140-/- to identify potential mRNA targets of miR-140. 2 M-BM-5g of total RNA was reverse transcribed with SuperScript II and second strand cDNA was synthesized. Biotinylated antisense cRNAs was amplified and transcribed using the GeneChip expression 3M-bM-^@M-^Y-Amplification reagent (Affymetrix). Finally, 10 M-BM-5g of cRNAs were fragmented and hybridized to GeneChip (R) Mouse Genome 430 2.0 array (Affymetrix). Microarray data were summarized by Robust Multichip Average (RMA) method and statistical analysis was performed using NIA Array Analysis (http://Igusun.grc.nia.nih.gov/ANOVA/).
Project description:MiR-140 is selectively expressed in cartilage. Deletion of the entire miR-140 locus in mice results in a growth retardation phenotype and an early-onset osteoarthritis-like pathology, however the relative contribution of miR-140-5p or miR-140-3p to the phenotype remains to be determined. An unbiased small RNA sequencing approach identified that miR-140-3p was in vast abundance (>10-fold) to miR-140-5p in human cartilage. Analysis of these data identified multiple miR-140-3p isomiRs differing from the miRBase [1] annotation at both the 5´ and 3´ end, with >99% of miR-140-3p isomiRs having one of two ‘seed’ sequences (5´ bases 2-8). The most abundant isomiR with each seed were selected for further analysis; miR-140-3p.2 which has an identical seed to the miRBase miR-140-3p (ACCACAG) and miR-140-3p.1 which has an altered seed (CCACAGG), and thus different potential targets. Each isomiR was overexpressed in chondrocytes and whole-genome transcriptomics used to identify targets. miR-140-3p.1 and miR-140-3p.2 significantly down-regulated 694 and 238 genes respectively (adj.P.Val<0.05), of which only 162 genes were commonly down-regulated by both isomiRs. Targets of both isomiRs were validated using 3´UTR luciferase assays. A significant enrichment of miR-140-3p.1 targets was identified within genes whose expression increase in the rib chondrocytes of Mir140-null mice and within genes whose expression decreased during human chondrogenesis. Finally, through imputing the expression of miR-140 from the expression of the host gene WWP2 in 124 previously published datasets an inverse correlation with miR-140-3p.1 predicted targets was identified. Together these data suggest the novel seed containing isomiR miR-140-3p.1 is more functional than the original consensus miR-140-3p or the isomiR with the same seed, miR-140-3p.2.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression. Heterozygous loss-of-function point mutations of miRNA genes are associated with several human congenital disorders, but neomorphic (gain-of-new-function) mutations in miRNAs due to nucleotide substitutions have not been reported. Here we describe a neomorphic seed region mutation in the chondrocyte-specific, super-enhancer-associated MIR140 gene encoding microRNA-140 (miR-140) in a novel autosomal dominant human skeletal dysplasia. Mice with the corresponding single nucleotide substitution show skeletal abnormalities similar to those of the patients but distinct from those of miR-140-null mice. This mutant miRNA gene yields abundant mutant miR-140-5p expression without miRNA-processing defects. In chondrocytes, the mutation causes widespread derepression of wild-type miR-140-5p targets and repression of mutant miR-140-5p targets, indicating that the mutation produces both loss-of-function and gain-of-function effects. Furthermore, the mutant miR-140-5p seed competes with the conserved RNA-binding protein Ybx1 for overlapping binding sites. This finding may explain the potent target repression and robust in vivo effect by this mutant miRNA even in the absence of evolutionary selection of miRNA–target RNA interactions, which contributes to the strong regulatory effects of conserved miRNAs. Our study presents the first case of a pathogenic gain-of-function miRNA mutation and provides molecular insight into neomorphic actions of emerging and/or mutant miRNAs.
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:BackgroundCopy number variation is an important dimension of genetic diversity and has implications in development and disease. As an important model organism, the mouse is a prime candidate for copy number variant (CNV) characterization, but this has yet to be completed for a large sample size. Here we report CNV analysis of publicly available, high-density microarray data files for 351 mouse tail samples, including 290 mice that had not been characterized for CNVs previously.ResultsWe found 9634 putative autosomal CNVs across the samples affecting 6.87% of the mouse reference genome. We find significant differences in the degree of CNV uniqueness (single sample occurrence) and the nature of CNV-gene overlap between wild-caught mice and classical laboratory strains. CNV-gene overlap was associated with lipid metabolism, pheromone response and olfaction compared to immunity, carbohydrate metabolism and amino-acid metabolism for wild-caught mice and classical laboratory strains, respectively. Using two subspecies of wild-caught Mus musculus, we identified putative CNVs unique to those subspecies and show this diversity is better captured by wild-derived laboratory strains than by the classical laboratory strains. A total of 9 genic copy number variable regions (CNVRs) were selected for experimental confirmation by droplet digital PCR (ddPCR).ConclusionThe analysis we present is a comprehensive, genome-wide analysis of CNVs in Mus musculus, which increases the number of known variants in the species and will accelerate the identification of novel variants in future studies.