N17 Modifies Mutant Huntingtin Nuclear Pathogenesis and Severity of Disease in HD BAC Transgenic Mice
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE64386 | GEO | 2015/02/05
SECONDARY ACCESSION(S): PRJNA270867
REPOSITORIES: GEO
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Project description:Longitudinal microarray data from BACHD-M-NM-^TN17 mice with wildtype littermate controls Total RNA from cortex and striatum of wildtype and BACHD-M-NM-^TN17 mice collected at 2mo, 7mo, and 11mo was used for microarray on the Illumina MouseRef8v.2 platform.
2015-02-05 | E-GEOD-64386 | biostudies-arrayexpress
Project description:The nucleus is a critical subcellular compartment for the pathogenesis of polyglutamine disorders, including Huntington's disease (HD). Recent studies suggest the first 17-amino-acid domain (N17) of mutant huntingtin (mHTT) mediates its nuclear exclusion in cultured cells. Here, we test whether N17 could be a molecular determinant of nuclear mHTT pathogenesis in vivo. BAC transgenic mice expressing mHTT lacking the N17 domain (BACHD-ΔN17) show dramatically accelerated mHTT pathology exclusively in the nucleus, which is associated with HD-like transcriptionopathy. Interestingly, BACHD-ΔN17 mice manifest more overt disease-like phenotypes than the original BACHD mice, including body weight loss, movement deficits, robust striatal neuron loss, and neuroinflammation. Mechanistically, N17 is necessary for nuclear exclusion of small mHTT fragments that are part of nuclear pathology in HD. Together, our study suggests that N17 modifies nuclear pathogenesis and disease severity in HD mice by regulating subcellular localization of known nuclear pathogenic mHTT species.
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Project description:Huntington’s disease (HD) is caused by CAG repeat expansion at the N-terminal region of huntingtin (HTT) gene and characterize by neuronal cell loss and neuroinflammation transcriptional profile change in striatum, cortex and other brain regions. Here we reported generation and characterization of BAC-CAG, a novel full length human HD mouse model host over 120 uninterrupted CAG repeats. we performed RNA-seq analysis of the striatum and cortex of BAC-CAG mice at 2m, 6m and 12m of age (N=6 per genotype, sex balanced). We observed an age-dependent transcriptionopathy in the striatum of BAC-CAG mice, with only 7 and 36 significant DE genes in 2m and 6m striatum respectively (FDR<0.1), but 820 DE genes (538 downregulated and 282 upregulated genes) at 12m of age (FDR<0.1). The transcriptomic deficits in this model are highly striatum-selective, as we only detected 4, 3 and 14 DE genes (FDR<0.1) at 2m, 6m and 12m respectively in BAC-CAG cortices compared to WT controls. Remarkably, we found a highly significant positive transcriptome-wide correlation (r=0.62) of DE Z statistics between BAC-CAG vs WT at 12m and Q140 vs WT at 6m (p<1e-200). This result demonstrates a high concordance of both upregulated and downregulated genes in the BAC-CAG striatum compared to that of allelic series KI mice; but RNA-seq studies of BACHD mice at 12m and found only 50 genes significantly differentially expressed (DE) genes (FDR<0.1) in the striatum at 12m of age compared to WT littermates, 31 downregulated and 19 upregulated genes. In the cortex at 12m of age, BACHD only showed 6 significantly downregulated genes and 7 upregulated genes comapred to WT controls (FDR<0.1).
2022-02-02 | GSE153827 | GEO
Project description:In Huntington's disease (HD), the uninterrupted CAG repeat length, but not the polyglutamine length, predicts disease onset. However, the underlying pathobiology remains unclear. Here, we developed bacterial artificial chromosome (BAC) transgenic mice expressing human mutant huntingtin (mHTT) with uninterrupted, and somatically unstable, CAG repeats that exhibit progressive disease-related phenotypes. Unlike prior mHTT transgenic models with stable, CAA-interrupted, polyglutamine-encoding repeats, BAC-CAG mice show robust striatum-selective nuclear inclusions and transcriptional dysregulation resembling those in murine huntingtin knockin models and HD patients. Importantly, the striatal transcriptionopathy in HD models is significantly correlated with their uninterrupted CAG repeat length but not polyglutamine length. Finally, among the pathogenic entities originating from mHTT genomic transgenes and only present or enriched in the uninterrupted CAG repeat model, somatic CAG repeat instability and nuclear mHTT aggregation are best correlated with early-onset striatum-selective molecular pathogenesis and locomotor and sleep deficits, while repeat RNA-associated pathologies and repeat-associated non-AUG (RAN) translation may play less selective or late pathogenic roles, respectively.
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Project description:C9orf72 ALS/FTD patients show remarkable clinical heterogeneity, but the complex biology of the repeat expansion mutation has limited our understanding of the disease. BAC transgenic mice were used to better understand the molecular mechanisms and repeat length effects of C9orf72 ALS/FTD. Genetic analyses of these mice demonstrate that the BAC transgene and not integration site effects cause ALS/FTD phenotypes. Transcriptomic changes in cell proliferation, inflammation and neuronal pathways are found late in disease and alternative splicing changes provide early molecular markers that worsen with disease progression. Isogenic sublines of mice with 800, 500 or 50 G4C2 repeats generated from the single-copy C9-500 line show longer repeats result in earlier onset, increased disease penetrance and increased levels of RNA foci and dipeptide RAN protein aggregates. These data demonstrate G4C2 repeat length is an important driver of disease and identify alternative splicing changes as early biomarkers of C9orf72 ALS/FTD.
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Project description:The N-terminal 17 amino acids of huntingtin (NT17) can be phosphorylated on serines 13 and 16; however, the significance of these modifications in Huntington's disease pathogenesis remains unknown. In this study, we developed BAC transgenic mice expressing full-length mutant huntingtin (fl-mhtt) with serines 13 and 16 mutated to either aspartate (phosphomimetic or SD) or alanine (phosphoresistant or SA). Both mutant proteins preserve the essential function of huntingtin in rescuing knockout mouse phenotypes. However, fl-mhtt-induced disease pathogenesis, including motor and psychiatric-like behavioral deficits, mhtt aggregation, and selective neurodegeneration are abolished in SD but preserved in SA mice. Moreover, modification of these serines in expanded repeat huntingtin peptides modulates aggregation and amyloid fibril formation in vitro. Together, our findings demonstrate that serines 13 and 16 are critical determinants of fl-mhtt-induced disease pathogenesis in vivo, supporting the targeting of huntingtin NT17 domain and its modifications in HD therapy.
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Project description:Under previously developed culture conditions, mouse and human intestinal epithelia can be cultured and expanded over long periods. These so-called organoids recapitulate the three-dimensional architecture of the gut epithelium, and consist of all major intestinal cell types. One key advantage of these ex vivo cultures is their accessibility to live imaging. So far the establishment of transgenic fluorescent reporter organoids has required the generation of transgenic mice, a laborious and time-consuming process, which cannot be extended to human cultures. Here we present a transfection protocol that enables the generation of recombinant mouse and human reporter organoids using BAC (bacterial artificial chromosome) technology.
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Project description:HD R6/1 transgenic mouse line brain hemispheres dissected. RNA targets were created for transgenics and wildtypes at time points 18, 22 and 27 weeks. Profiles and data analysis performed using the Bioconductor software and linear model contrasts using LIMMA on RMA probeset summarys. Experiment Overall Design: 18 samples extracted, 3 transgenic plus 3 littermate controls analysed at each timepoint.
2009-04-23 | E-GEOD-3621 | biostudies-arrayexpress
Project description:The endocannabinoid system (ECS) is a retrograde messenger system, consisting of lipid signaling molecules that bind to at least two G-protein-coupled receptors, Cannabinoid receptor 1 and 2 (CB1 and 2). As CB2 is primarily expressed on immune cells such as B cells, T cells, macrophages, dendritic cells, and microglia, it is of great interest how CB2 contributes to immune cell development and function in health and disease. Here, understanding the mechanisms of CB2 involvement in immune-cell function as well as the trafficking and regulation of CB2 expressing cells are crucial issues. Up to now, CB2 antibodies produce unclear results, especially those targeting the murine protein. Therefore, we have generated BAC transgenic GFP reporter mice (CB2-GFPTg) to trace CB2 expression in vitro and in situ. Those mice express GFP under the CB2 promoter and display GFP expression paralleling CB2 expression on the transcript level in spleen, thymus and brain tissue. Furthermore, by using fluorescence techniques we show that the major sources for GFP-CB2 expression are B cells in spleen and blood and microglia in the brain. This novel CB2-GFP transgenic reporter mouse line represents a powerful resource to study CB2 expression in different cell types. Furthermore, it could be used for analyzing CB2-mediated mobilization and trafficking of immune cells as well as studying the fate of recruited immune cells in models of acute and chronic inflammation.
| S-EPMC4583291 | biostudies-literature
Project description:BackgroundThe length of the huntingtin (HTT) CAG repeat is strongly correlated with both age at onset of Huntington's disease (HD) symptoms and age at death of HD patients. Dichotomous analysis comparing HD to controls is widely used to study the effects of HTT CAG repeat expansion. However, a potentially more powerful approach is a continuous analysis strategy that takes advantage of all of the different CAG lengths, to capture effects that are expected to be critical to HD pathogenesis.Methodology/principal findingsWe used continuous and dichotomous approaches to analyze microarray gene expression data from 107 human control and HD lymphoblastoid cell lines. Of all probes found to be significant in a continuous analysis by CAG length, only 21.4% were so identified by a dichotomous comparison of HD versus controls. Moreover, of probes significant by dichotomous analysis, only 33.2% were also significant in the continuous analysis. Simulations revealed that the dichotomous approach would require substantially more than 107 samples to either detect 80% of the CAG-length correlated changes revealed by continuous analysis or to reduce the rate of significant differences that are not CAG length-correlated to 20% (n = 133 or n = 206, respectively). Given the superior power of the continuous approach, we calculated the correlation structure between HTT CAG repeat lengths and gene expression levels and created a freely available searchable website, "HD CAGnome," that allows users to examine continuous relationships between HTT CAG and expression levels of ∼20,000 human genes.Conclusions/significanceOur results reveal limitations of dichotomous approaches compared to the power of continuous analysis to study a disease where human genotype-phenotype relationships strongly support a role for a continuum of CAG length-dependent changes. The compendium of HTT CAG length-gene expression level relationships found at the HD CAGnome now provides convenient routes for discovery of candidates influenced by the HD mutation.
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