Project description:We used gene array analysis of cortical bone to identify Phex-dependent gene transcripts regulating Fgf23 production and mineralization in Hyp mice. We discovered that activation of Fgf receptor- and Wnt-pathways contribute to increased Ffg23 gene transcription in Hyp bone. We found evidence in Hyp bone for increased expression of Fgf1, Fgf7, and Egr2 in the Fgf-signaling pathway and decrements in Sost and Cpz and increments in Sfrp1 and 4 in the Wnt-signaling pathway. Moreover, activation of Fgf and Wnt-signaling stimulated, whereas Tgf β inhibited Fgf23 promoter activity in osteoblasts. We also observed reductions in Bmp1, a metalloproteinase that metabolizes the Fgf23 regulatory extracellular matrix protein Dmp1. These findings suggest that elevation of Fgf23 expression in osteocytes is regulated by interactions between cell surface expression of Phex, extracellular matrix proteins and paracrine effects of Fgf and Wnt. Alterations were also found in enzymes regulating the posttranslational processing and stability of Fgf23, including decrements in the glycosyltransferase Galnt3 and the proprotein convertase Pcsk5. In addition, we found that the Pcsk5 and the glycosyltransferase Galnt3 were decreased in Hyp bone, suggesting that reduced post-translational processing of FGF23 may also contribute to increased Fgf23 levels in Hyp mice. With regards to mineralization, we identified additional candidates to explain the intrinsic mineralization defect in Hyp osteoblasts, including increases in the mineralization inhibitors Mgp and Thbs4, as well as increases in local pH altering factors, carbonic anhydrase 12 (Car12) and 3 (Car3) and the sodium-dependent citrate transporter (Slc13a5). These studies demonstrate the complexity of gene expression alterations in bone that accompanies inactivating Phex mutations and identify novel pathways that may coordinate Fgf23 expression and mineralization of extracellular matrix in Hyp bone. We isolated total RNAs from long bones of both WT and Hyp mice at 12 days of age. Since the RNA yields from the long bones are very low, we combined 2 bone samples with same genotype (WT or Hyp) for one RNA extraction. We will compare the difference of the gene expressions between Hyp and WT. We will use 4 samples in each animal condition.
Project description:We used gene array analysis of cortical bone to identify Phex-dependent gene transcripts regulating Fgf23 production and mineralization in Hyp mice. We discovered that activation of Fgf receptor- and Wnt-pathways contribute to increased Ffg23 gene transcription in Hyp bone. We found evidence in Hyp bone for increased expression of Fgf1, Fgf7, and Egr2 in the Fgf-signaling pathway and decrements in Sost and Cpz and increments in Sfrp1 and 4 in the Wnt-signaling pathway. Moreover, activation of Fgf and Wnt-signaling stimulated, whereas Tgf β inhibited Fgf23 promoter activity in osteoblasts. We also observed reductions in Bmp1, a metalloproteinase that metabolizes the Fgf23 regulatory extracellular matrix protein Dmp1. These findings suggest that elevation of Fgf23 expression in osteocytes is regulated by interactions between cell surface expression of Phex, extracellular matrix proteins and paracrine effects of Fgf and Wnt. Alterations were also found in enzymes regulating the posttranslational processing and stability of Fgf23, including decrements in the glycosyltransferase Galnt3 and the proprotein convertase Pcsk5. In addition, we found that the Pcsk5 and the glycosyltransferase Galnt3 were decreased in Hyp bone, suggesting that reduced post-translational processing of FGF23 may also contribute to increased Fgf23 levels in Hyp mice. With regards to mineralization, we identified additional candidates to explain the intrinsic mineralization defect in Hyp osteoblasts, including increases in the mineralization inhibitors Mgp and Thbs4, as well as increases in local pH altering factors, carbonic anhydrase 12 (Car12) and 3 (Car3) and the sodium-dependent citrate transporter (Slc13a5). These studies demonstrate the complexity of gene expression alterations in bone that accompanies inactivating Phex mutations and identify novel pathways that may coordinate Fgf23 expression and mineralization of extracellular matrix in Hyp bone.
Project description:That phosphate homeostasis is tightly linked to skeletal mineralization is probably best underscored by the fact that the phosphaturic hormone FGF23 is primarily expressed by terminally differentiated osteoblasts/osteocytes, and that increased circulating FGF23 levels are causative for different types of hypophosphatemic rickets. In contrast, FGF23-inactivation results in hyperphosphatemia, and unexpectedly this phenotype is associated with severe osteomalacia in Fgf23-deficient mice. In this context it is interesting that different types of bone cells have been shown to respond to extracellular phosphate, thereby raising the concept that phosphate can act as a signaling molecule. To identify phosphate-responsive genes in primary murine osteoblasts we performed genome-wide expression analysis with cells maintained in medium containing either 1 mM or 4 mM sodium phosphate for 6 hours. As confirmed by qRT-PCR, this analysis revealed that several known osteoblast differentiation markers (Bglap, Ibsp or Phex) were unaffected by raising extracellular phosphate levels. In contrast, we found that the expression of Enpp1 and Ank, two genes encoding inhibitors of matrix mineralization, was induced by extracellular phosphate, while the expression of Sost and Dkk1, two genes encoding inhibitors of bone formation, was negatively regulated. The ability of osteoblasts to respond to extracellular phosphate was dependent on their differentiation state, and shRNA-dependent repression of the phosphate transporter Slc20a1 in MC3T3-E1 cells partially abolished their molecular response to phosphate. Taken together, our results provide further evidence for a role of extracellular phosphate as a signaling molecule and raise the possibility that severe hyperphosphatemia can negatively affect skeletal mineralization.
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:The pathophysiology of the osteomalacia in X-linked hypophosphatemia is uncertain. In this project, genomic DNA microarrays were used to identify novel genes with abnormal mRNA expression levels in mice with the dominant Hyp mutation of the Phex gene. Femoral shafts from five-week-old C57BL/6J mice, male and female, normal and Hyp (hemizygous male and heterozygous female), were flushed with saline to remove the marrow. RNA was extracted from each bone, pooled between two mice for each array, processed to cRNA, and hybridized to Affymetrix Mouse 430 2.0 GeneChip microarrays with probe sets for 45,101 genes. Twenty microarrays (40 mice) were done with 5 arrays for each treatment group (normal male, Hyp male, normal female and Hyp female). For each gene, factorial analysis of variance was performed for the main effects of genotype (normal vs. Hyp), sex (male vs. female), and genotype-by-sex interaction. The mRNA levels for 54 % of the genes on each array were scored as present. At P < 0.01, 2,635 genes were significant for genotype, 1,488 for sex, and 509 for genotype-by-sex interaction. There were two probes sets for the Phex gene. Probe 1450445, at the 3â end of the coding sequence, was low in normal samples (246 ± 37 (10), mean ± SEM (n)) and absent in Hyp samples. Probe 1421979, at the far 3â end of the untranslated region of the cDNA, 3,000 base pairs from the coding sequence, was high in normal mice (3,915 ± 315 (10); 8x brighter than the average gene), undetectable in Hyp males, and 725 ± 93 (5) in Hyp females. Both probe sets were scored as absent in kidney tissue. In Hyp bone, male and female, there was significant down-regulation of markers of osteoblasts and bone matrix synthesis with significant up-regulation of markers of blood vessel formation and cytoskeleton. No prominent skeletal gene was up-regulated in Hyp to attempt to compensate for the low skeletal mineralization. The genes with significant genotype-by-sex interaction did not show a marked fold difference between male and female Hyp mice. In conclusion, male and female Hyp mice showed similar depression of mRNA levels of genes related to bone synthesis in the femoral shaft. There was a high signal level from probes for a sequence in the 3â untranslated region of the Phex gene of normal, but not Hyp, mice, suggesting the need for further study of the molecular organization of this gene. Experiment Overall Design: Equal amounts of RNA from two mice, matched for genotype and sex were pooled to create each sample for microarray analysis. Four treatment groups were done: (1) Normal male mice, (2) Hyp male mice, (3) normal female mice, and (4) Hyp female mice. Five replicates were done with each replicate containing one sample from each of the four treatment groups for a total of 20 independent samples (40 mice total). Each replicate was matched for littermates and parallel processing.
Project description:The pathophysiology of the osteomalacia in X-linked hypophosphatemia is uncertain. In this project, genomic DNA microarrays were used to identify novel genes with abnormal mRNA expression levels in mice with the dominant Hyp mutation of the Phex gene. Femoral shafts from five-week-old C57BL/6J mice, male and female, normal and Hyp (hemizygous male and heterozygous female), were flushed with saline to remove the marrow. RNA was extracted from each bone, pooled between two mice for each array, processed to cRNA, and hybridized to Affymetrix Mouse 430 2.0 GeneChip microarrays with probe sets for 45,101 genes. Twenty microarrays (40 mice) were done with 5 arrays for each treatment group (normal male, Hyp male, normal female and Hyp female). For each gene, factorial analysis of variance was performed for the main effects of genotype (normal vs. Hyp), sex (male vs. female), and genotype-by-sex interaction. The mRNA levels for 54 % of the genes on each array were scored as present. At P < 0.01, 2,635 genes were significant for genotype, 1,488 for sex, and 509 for genotype-by-sex interaction. There were two probes sets for the Phex gene. Probe 1450445, at the 3’ end of the coding sequence, was low in normal samples (246 ± 37 (10), mean ± SEM (n)) and absent in Hyp samples. Probe 1421979, at the far 3’ end of the untranslated region of the cDNA, 3,000 base pairs from the coding sequence, was high in normal mice (3,915 ± 315 (10); 8x brighter than the average gene), undetectable in Hyp males, and 725 ± 93 (5) in Hyp females. Both probe sets were scored as absent in kidney tissue. In Hyp bone, male and female, there was significant down-regulation of markers of osteoblasts and bone matrix synthesis with significant up-regulation of markers of blood vessel formation and cytoskeleton. No prominent skeletal gene was up-regulated in Hyp to attempt to compensate for the low skeletal mineralization. The genes with significant genotype-by-sex interaction did not show a marked fold difference between male and female Hyp mice. In conclusion, male and female Hyp mice showed similar depression of mRNA levels of genes related to bone synthesis in the femoral shaft. There was a high signal level from probes for a sequence in the 3’ untranslated region of the Phex gene of normal, but not Hyp, mice, suggesting the need for further study of the molecular organization of this gene. Keywords: 2x2 factorial design with complete blocks
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.
Project description:BackgroundLong terminal repeat (LTR) retrotransposons make up a large fraction of the typical mammalian genome. They comprise about 8% of the human genome and approximately 10% of the mouse genome. On account of their abundance, LTR retrotransposons are believed to hold major significance for genome structure and function. Recent advances in genome sequencing of a variety of model organisms has provided an unprecedented opportunity to evaluate better the diversity of LTR retrotransposons resident in eukaryotic genomes.ResultsUsing a new data-mining program, LTR_STRUC, in conjunction with conventional techniques, we have mined the GenBank mouse (Mus musculus) database and the more complete Ensembl mouse dataset for LTR retrotransposons. We report here that the M. musculus genome contains at least 21 separate families of LTR retrotransposons; 13 of these families are described here for the first time.ConclusionsAll families of mouse LTR retrotransposons are members of the gypsy-like superfamily of retroviral-like elements. Several different families of unrelated non-autonomous elements were identified, suggesting that the evolution of non-autonomy may be a common event. High sequence similarity between several LTR retrotransposons identified in this study and those found in distantly-related species suggests that horizontal transfer has been a significant factor in the evolution of mouse LTR retrotransposons.
Project description:House mice (Mus musculus) emit ultrasonic vocalizations (USVs), which are surprisingly complex and have features of bird song, but their functions are not well understood. Previous studies have reported mixed evidence on whether there are sex differences in USV emission, though vocalization rate or other features may depend upon whether potential receivers are of the same or opposite sex. We recorded the USVs of wild-derived adult house mice (F1 of wild-caught Mus musculus musculus), and we compared the vocalizations of males and females in response to a stimulus mouse of the same- or opposite-sex. To detect and quantify vocalizations, we used an algorithm that automatically detects USVs (Automatic Mouse Ultrasound Detector or A-MUD). We found high individual variation in USV emission rates (4 to 2083 elements/10 min trial) and a skewed distribution, with most mice (60%) emitting few (≤50) elements. We found no differences in the rates of calling between the sexes overall, but mice of both sexes emitted vocalizations at a higher rate and higher frequencies during opposite- compared to same-sex interactions. We also observed a trend toward higher amplitudes by males when presented with a male compared to a female stimulus. Our results suggest that mice modulate the rate and frequency of vocalizations depending upon the sex of potential receivers.