Project description:Age-related hearing loss (AHL) is the progressive loss of auditory function with aging. The DBA/2J (DBA) mice have been used as a model of AHL and undergoes progressive, age-related hearing loss by 12 weeks of age. Here we analyzed cochlear gene expression of 7-week-old and 36-week-old DBA mice using microarrays. Auditory brainstem response (ABR) analysis confrimed that severe age-related hearing loss occured in 36-week-old mice, whereas moderate hearing loss occured in 7-week-old mice. Comprehensive gene expression analysis identified genes correlated with AHL and revealeed that 15 mitochondrial process categories, including “mitochondrial electron transport chain”, “oxidative phosphorylation”, “respiratory chain complex I”, “respiratory chain complex IV”, and “respiratory chain complex V”, were statistically associated with AHL-correlated genes in the cochlea of 36-week-old DBA mice, and that 25 genes encoding components of the mitochondrial respiratory chain (respiratory chain complex I, IV, and V) were significantly down-regulated in the cochlea. These observations provide evidence that AHL is associated with down-regulation of genes involved in the mitochondrial respiratory chain in the cochlea of DBA mice, and suggest that mitochondrial respiratory chain dysfunction may be a key feature of AHL in mammalian cochlea. Keywords: Disease state analysis, Time course analysis
Project description:performed a genetic screen for microRNAs that are differentially expressed between LSK, LS−K+, erythroid and myeloid cells isolated from C57BL/6 and DBA/2 mice. This analysis identified 131 microRNAs that were differentially expressed between cell types and 15 that were differentially expressed between mouse strains. Of special interest was an evolutionary conserved miR-cluster located on chromosome 17 consisting of miR-99b, let-7e and miR-125a. All cluster members were most highly expressed in LSKs and down-regulated upon differentiation. In addition, these microRNAs were higher expressed in DBA/2 cells compared to C57BL/6 cells, and thus correlated with HSPC frequency. To functionally characterize these microRNAs, we overexpressed the entire miR-cluster 99b/let-7e/125a and miR-125a alone in BM cells from C57BL/6 mice. Overexpression of the miR-cluster or miR-125a dramatically increased day-35 CAFC activity and caused severe hematopoietic phenotypes upon transplantation. We showed that a single member of the miR-cluster, namely miR-125a, is responsible for the majority of the observed miR-cluster overexpression effects. Finally, we performed genome-wide gene expression arrays and identified candidate target genes through which miR-125a may modulate HSPC fate.
Project description:Mlycd encodes malonyl-CoA decarboxylase (MCD), which is an enzyme that localizes in the cytosolic, mitochondrial, and peroxisomal compartments and catalyzes the conversion of malonyl-CoA into acetyl-CoA. Malonyl-CoA can be converted into malonylcarnitine (C3DC). Patients with an autosomal recessive defect of MCD and MCD KO mice have pronounced elevations of C3DC. Analysis of plasma C3DC levels in the BxD genetic reference population revealed increased levels in BxD strains that harbor the DBA/2J haplotype at the site of the Mlycd gene. RNA sequencing was performed on two samples of DBA/2J mouse livers and two C57BL/6J mouse livers. Decreased expression of Mlycd gene as well as intronic reads in intron 2 were observed in DBA/2J livers. Long-read sequecing of DBA/2J livers in the Mlycd region confirmed an intracisternal A-particle (IAP) retrotransposon in intron 2 of the DBA/2J Mlycd sequence. To confirm the causal nature of the variant, DBA/2J mice with and without the C57BL/6J variant of Mlycd spliced in were tested for products of MCD enzymatic activity, and the C57BL/6J variant was able to rescue the phenotype seen in the DBA/2J mice.
Project description:Aging of mice can be tracked by DNA methylation changes at specific sites in the genome. In this study, we used the Infinium Mouse Methylation BeadChip to compare such epigenetic modifications in C57BL/6 (B6) and DBA/2J (DBA) mice. There were marked differences in age-associated DNA methylation in these commonly used mouse strains. In B6 the age-associated DNA methylation revealed general age-associated hypomethylation with focused hypermethylation at CpG islands, whereas this was hardly observed in DBA mice. The CpGs with highest age-correlation were overlapping in B6 and DBA and included the genes Hsf4, Prima1, Aspa, and Wnt3a. Notably, Hsf4, Prima1 were also top candidates in previous studies based on whole genome deep sequencing approaches. Furthermore, Hsf4, Aspa, and Wnt3a revealed highly significant age-associated DNA methylation in the homologous regions in human. Taken together, age-associated DNA methylation differs between B6 and DBA, but the most prominent regions are conserved, even in humans.
Project description:C57BL/6J mice were 105-fold more resistant to Chlamydia psittaci infection than DBA/2J mice by LD100 determinations. Linkage analysis using BXD recombinant inbred strains revealed a single effector locus at a 1.5 Mbp region on chromosome 11 encoding a cluster of three p47GTPases (Irgb10, Igtp, and Iigp2). Western blots of infected tissue showed that Irgb10 was elevated in resistant mice and one of the two possible Iigp2 protein isoforms was preferentially expressed in susceptible mice. The BXD39 strain, susceptible at Irgb10 and resistant at Iigp2, had an intermediate phenotype, implicating the non-redundant role of these p47GTPases. C57BL/6J and DBA/2J exhibited a difference in IFNg dependent chlamydial control, which was reversible by Iigp2 siRNA knockdown. Microarrays of infected peritoneal lavage revealed >10 fold up regulation of neutrophil recruiting chemokines in susceptible mice and >100 fold increase in macrophage differentiation genes in resistant mice, indicating that susceptibility pattern involves stimulation of different inflammatory cell recruiting pathways. Massive neutrophil recruitment was seen in susceptible mice by histology and flow cytometry, and neutrophil chemokine receptor (CXCR2) knockout mice on a susceptible background survived lethal challenge confirming that neutrophil recruitment was required for susceptibility. Congenic Igtp knockout mice also susceptible at Irgb10 and Iigp2 on a resistant background recruited neutrophils and succumbed to infection. We conclude that Irgb10 and Iigp2 act together to confer differential susceptibility against murine chlamydial infection. Results indicate that these p47GTPases have cell autonomous effects, which results in vastly different inflammatory stimulation leading to either recovery or death. Keywords: Comparative disease state analysis
Project description:performed a genetic screen for microRNAs that are differentially expressed between LSK, LS−K+, erythroid and myeloid cells isolated from C57BL/6 and DBA/2 mice. This analysis identified 131 microRNAs that were differentially expressed between cell types and 15 that were differentially expressed between mouse strains. Of special interest was an evolutionary conserved miR-cluster located on chromosome 17 consisting of miR-99b, let-7e and miR-125a. All cluster members were most highly expressed in LSKs and down-regulated upon differentiation. In addition, these microRNAs were higher expressed in DBA/2 cells compared to C57BL/6 cells, and thus correlated with HSPC frequency. To functionally characterize these microRNAs, we overexpressed the entire miR-cluster 99b/let-7e/125a and miR-125a alone in BM cells from C57BL/6 mice. Overexpression of the miR-cluster or miR-125a dramatically increased day-35 CAFC activity and caused severe hematopoietic phenotypes upon transplantation. We showed that a single member of the miR-cluster, namely miR-125a, is responsible for the majority of the observed miR-cluster overexpression effects. Finally, we performed genome-wide gene expression arrays and identified candidate target genes through which miR-125a may modulate HSPC fate. Microarray-based microRNA profiling study was peformed of four developmentally related hematopoietic cell types isolated from the BM of B6 and D2 mice. Total RNA isolated from purified LSK multilineage cells, committed LS−K+ cells, erythroid TER-119+ cells and myeloid Gr-1+ cells was hybridized to Agilent microRNA arrays. Triplicates were generated for each of the 8 conditions (4 cell types, 2 mouse strains). From the final anaysis one replicate for B6 LS-K+ cells was removed based on PCA, therefore B6 Prog group consist of only 2 biological replicates.
Project description:Age-related hearing loss (AHL) is the progressive loss of auditory function with aging. The DBA/2J (DBA) mice have been used as a model of AHL and undergoes progressive, age-related hearing loss by 12 weeks of age. Here we analyzed cochlear gene expression of 7-week-old and 36-week-old DBA mice using microarrays. Auditory brainstem response (ABR) analysis confrimed that severe age-related hearing loss occured in 36-week-old mice, whereas moderate hearing loss occured in 7-week-old mice. Comprehensive gene expression analysis identified genes correlated with AHL and revealeed that 15 mitochondrial process categories, including â??mitochondrial electron transport chainâ??, â??oxidative phosphorylationâ??, â??respiratory chain complex Iâ??, â??respiratory chain complex IVâ??, and â??respiratory chain complex Vâ??, were statistically associated with AHL-correlated genes in the cochlea of 36-week-old DBA mice, and that 25 genes encoding components of the mitochondrial respiratory chain (respiratory chain complex I, IV, and V) were significantly down-regulated in the cochlea. These observations provide evidence that AHL is associated with down-regulation of genes involved in the mitochondrial respiratory chain in the cochlea of DBA mice, and suggest that mitochondrial respiratory chain dysfunction may be a key feature of AHL in mammalian cochlea. Experiment Overall Design: To determine the effects of age-related hearing loss, each 7-week-old sample (n = 3) was compared to each 36-week-old sample (n = 3), generating a total of nine pairwise comparisons. Using DAVIS and EASE, the identified genes were assign to â??GO: Biological Processâ?? categories of Gene Ontology Consortium. Furthermore, we used EASE to determine the total number of genes that were assigned to each biological process category, and to perform Fisher exact test. Quality control measures were not used. No replicates were done. Dye swap was not used.
Project description:Analysis of tissues of DBA/2 mice fed a standard breeding diet (SBD) and high fat diet (HFD) revealed tissue specific roles in inflammation and disease, and altered communication between tissues. The tissues surveyed incuded adipose tissues (brown, inguinal, mesenteric, retro-peritoneal, subcutaneious and gonadal), muscle and liver.