Native functions of the androgen receptor are essential to pathogenesis in a Drosophila model of spinobulbar muscular atrophy
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ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE23802 | GEO | 2010/09/23
SECONDARY ACCESSION(S): PRJNA130695
REPOSITORIES: GEO
Similar Datasets
Project description:Spinobulbar muscular atrophy (SBMA) is a neurodegenerative disease caused by expansion of a polyglutamine tract in the androgen receptor (AR). This mutation confers toxic function to AR through unknown mechanisms. Mutant AR toxicity requires binding of its hormone ligand, suggesting that pathogenesis involves ligand-induced changes in AR. However, whether toxicity is mediated by native AR function or a novel AR function is unknown. We systematically investigated events downstream of ligand-dependent AR activation in a Drosophila model of SBMA. We show that nuclear translocation of AR is necessary but not sufficient for toxicity and that DNA binding by AR is necessary for toxicity. Mutagenesis studies demonstrated that a functional AF-2 domain is essential for toxicity, a finding corroborated by a genetic screen that identified AF-2 interactors as dominant modifiers of degeneration. These findings indicate that SBMA pathogenesis is mediated by misappropriation of native protein function, a mechanism that may apply broadly to polyglutamine diseases. We used Affymetrix arrays to generate a molecular phenotype of degeneration in profile flies expressing wild-type or polyglutamine-expanded AR. We also expressed in the fly eye polyglutamine-expanded AR with point mutations affecting the DNA binding domain and the AF-2 domain. In some experiments, GMR-GAL4; UAR-AR flies were crossed to flies carrying a chromosomal duplication of the limpet gene. Transgene expression was induced in the eye using GMR-GAL4. Flies were crossed at 29 deg C on food containing either 1mM DHT or 1% ethanol (vehicle).
2010-09-23 | E-GEOD-23802 | biostudies-arrayexpress
Project description:Expansion of a polyglutamine (polyQ) tract in the gene for the androgen receptor (AR) results in partial loss of transactivation function and causes spinobulbar muscular atrophy (SBMA). Modification of AR by small ubiquitin-like modifier (SUMO) reduces AR function in a promoter context-dependent manner. We used microarrays to confirm and demonstrate loss of AR function from polyQ expansion and to test the degree to which AR function is altered by preventing polyQ AR SUMOylation. PC12 cells expressing AR10Q, AR112Q, or nonSUMOylatable AR112Q (KRKR) in the presence or absence of synthetic androgen R1881 were assessed for alterations in AR function by comparing gene expression changes with each AR variant in response to ligand.
2014-08-23 | E-GEOD-50383 | biostudies-arrayexpress
Project description:Spinal and bulbar muscular atrophy (SBMA) is a slowly progressing neuromuscular disease caused by a polyglutamine (polyQ)-encoding CAG repeat expansion in the androgen receptor (AR) gene, leading to AR aggregation, lower motor neuron death, and muscle atrophy. AR is a ligand-activated transcription factor that regulates neuronal architecture and promotes axon regeneration; however, whether AR transcriptional functions contribute to disease pathogenesis is not fully understood. Using a differentiated PC12 cell model of SBMA, we identified dysfunction of polyQ-expanded AR in its regulation of neurite growth and maintenance. Specifically, we found that in the presence of androgens, polyQ-expanded AR inhibited neurite outgrowth, induced neurite retraction, and inhibited neurite regrowth. This dysfunction was independent of polyQ-expanded AR transcriptional activity at androgen response elements (AREs). We further showed that the formation of polyQ-expanded AR intranuclear inclusions promoted neurite retraction, which coincided with reduced expression of the neuronal differentiation marker -III-Tubulin. Finally, we revealed that cell death is not the primary outcome for cells undergoing neurite retraction; rather, these cells become senescent. Our findings reveal that mechanisms independent of AR canonical transcriptional activity underly neurite defects in a cell model of SBMA and identify senescence as a previously unappreciated pathway implicated in this pathology. These findings suggest that, in the absence of a role for AR canonical transcriptional activity in the SBMA pathologies described here, the development of SBMA therapeutics that preserve this activity may be desirable. This approach may be broadly applicable to other polyglutamine diseases such as Huntington’s disease and spinocerebellar ataxias.
2024-07-05 | GSE267802 | GEO
Project description:Expansion of a polyglutamine (polyQ) tract in the gene for the androgen receptor (AR) results in partial loss of transactivation function and causes spinobulbar muscular atrophy (SBMA). Modification of AR by small ubiquitin-like modifier (SUMO) reduces AR function in a promoter context-dependent manner. We used microarrays to confirm and demonstrate loss of AR function from polyQ expansion and to test the degree to which AR function is altered by preventing polyQ AR SUMOylation.
2014-08-23 | GSE50383 | GEO
Project description:Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disorder caused by a polyglutamine expansion in the androgen receptor (AR). Previous studies have shown that transcriptional dysregulation and mitochondrial impairment occur in SBMA. We used gene-expression analysis and ChIP-sequencing to map transcriptional changes in SBMA induced pluripotent stem cell-derived motor neurons. The SBMA cells had decreased expression of genes encoding electron transport chain subunits and other metabolic proteins, associated with reduced histone acetylation which may be contributing to mitochondrial dysfunction. AR ChIP-sequencing results indicate that this is not a direct transcriptional effect of mutant AR on mitochondrial gene expression. Furthermore, we found decreased acetyl-CoA, and pyruvate supplementation to correct this deficiency improved mitochondrial function and SBMA motor neuron viability. We propose that epigenetic dysregulation of metabolic genes contributes to reduced mitochondrial ATP production. Our results show a molecular link between altered epigenetic regulation and mitochondrial metabolism that contributes to neurodegeneration.
2020-08-10 | GSE140016 | GEO
Project description:Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disorder caused by a polyglutamine expansion in the androgen receptor (AR). Previous studies have shown that transcriptional dysregulation and mitochondrial impairment occur in SBMA. We used gene-expression analysis and ChIP-sequencing to map transcriptional changes in SBMA induced pluripotent stem cell-derived motor neurons. The SBMA cells had decreased expression of genes encoding electron transport chain subunits and other metabolic proteins, associated with reduced histone acetylation which may be contributing to mitochondrial dysfunction. AR ChIP-sequencing results indicate that this is not a direct transcriptional effect of mutant AR on mitochondrial gene expression. Furthermore, we found decreased acetyl-CoA, and pyruvate supplementation to correct this deficiency improved mitochondrial function and SBMA motor neuron viability. We propose that epigenetic dysregulation of metabolic genes contributes to reduced mitochondrial ATP production. Our results show a molecular link between altered epigenetic regulation and mitochondrial metabolism that contributes to neurodegeneration.
2020-08-10 | GSE140015 | GEO
Project description:Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disorder caused by a polyglutamine expansion in the androgen receptor (AR). Previous studies have shown that transcriptional dysregulation and mitochondrial impairment occur in SBMA. We used gene-expression analysis and ChIP-sequencing to map transcriptional changes in SBMA induced pluripotent stem cell-derived motor neurons. The SBMA cells had decreased expression of genes encoding electron transport chain subunits and other metabolic proteins, associated with reduced histone acetylation which may be contributing to mitochondrial dysfunction. AR ChIP-sequencing results indicate that this is not a direct transcriptional effect of mutant AR on mitochondrial gene expression. Furthermore, we found decreased acetyl-CoA, and pyruvate supplementation to correct this deficiency improved mitochondrial function and SBMA motor neuron viability. We propose that epigenetic dysregulation of metabolic genes contributes to reduced mitochondrial ATP production. Our results show a molecular link between altered epigenetic regulation and mitochondrial metabolism that contributes to neurodegeneration.
2020-08-10 | GSE140017 | GEO
Project description:Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy’s Disease, is a slowly progressive adult-onset neuromuscular disease which results from a polyglutamine (polyQ) encoding CAG repeat expansion within the androgen receptor gene (AR). Despite the ubiquitous expression of the androgen receptor, it is unclear why motor neurons selectively degenerate and there are no effective treatments or disease modifying therapies for this debilitating disease. In order to identify potential therapeutic targets, we set out to establish the genes and molecular pathways involved in early motor neuron dysfunction in SBMA. We therefore undertook global transcriptomic profiling of cultured primary embryonic motor neurons from the spinal cord of AR100 mice, which model SBMA.. Four biological replicate samples were used for genome wide analysis using Affymetrix 430 v2.0 mouse arrays. Data was normalised using therobust multichip average (RMA) algorithm.
2019-05-02 | E-MTAB-6986 | biostudies-arrayexpress
Project description:Together with the Estrogen, Progesterone, and Glucocorticoid Receptors, the Androgen Receptor (AR) is a member of the type I nuclear receptor superfamily, a class of transcription factors that are activated by steroid hormones1. Nuclear receptors share a common three-domain structure, comprising a highly variable amino-terminal domain (NTD), with potent transcriptional activator capability, a central two zinc finger motifs DNA-binding domain (DBD), and a well-conserved carboxy-terminal ligand-binding domain (LBD) responsible for interacting with the transcriptional machinery1. Given their modular structure, expression of isoforms resulting from alternative splicing or starting and termination events have profound effects on nuclear receptor activity and function. Several AR variants (AR-Vs) have been identified from prostate cancer clinical specimens, arising from multiple mechanisms, including genomic rearrangements2 and upregulation of splicing factors3. This seminal discovery has provided the molecular basis for a deeper understanding of AR-related diseases, with potential to be translated in identification of novel therapeutic targets and promising prognostic markers4–6. By deeply sequencing the transcriptome of human brains, here we identified AR-2 as the most expressed AR isoform. Furthermore, we found that AR-2 is widely expressed in other human tissues, forms heterodimers with the full length AR and acts as a repressor of its transcriptional activity. Delivery of this isoform via adeno-associated virus (AAV9) resulted in significant amelioration of the disease phenotype in a mouse model of spinal and bulbar muscular atrophy (SBMA), a neuromuscular disease with unmet clinical need caused by a toxic gain of function of polyglutamine-expanded (polyQ) AR7. Collectively, these results establish a physiological role of AR-2 in fine-tuning full length AR activity and demonstrate the feasibility and therapeutic benefit of modulating this variant for treating SBMA and other AR-related diseases.
2021-06-29 | GSE138053 | GEO
Project description:Emerging evidence implicates transcriptional dyseregulation within skeletal muscle in the pathogenesis of Kennedy disease/spinal bulbar muscular atrophy (KD/SBMA). We therefore broadly characterized gene expression in skeletal muscle of three independently generated mouse models of this disorder. The mouse models included a polyglutamine expanded (polyQ) AR knock-in model (AR113Q KI), a polyQ AR transgenic model (AR97Q Tg), and a transgenic mouse which overexpresses wild type AR solely in muscle (HSA-AR Tg). We performed microarray analysis of lower hindlimb muscles taken from these three models using high density oligonucleotide arrays. Changes in gene expression relative to wild type controls were evaluated separately in each strain. We validated our results using quantitative RT-PCR. Patterns of gene expression that are common to all lines and unique to each are described. When considered globally, the degree of overlap between the three models is approximately equivalent, and several patterns of gene expression relevant to the disease process were observed. Notably, patterns of gene expression typical of loss of AR function were observed in all three models, as were alterations in genes involved in cell adhesion, energy balance, Huntingtonâ??s disease, muscle atrophy and myogenesis. By comparing patterns of gene expression in three independent models of KD/SBMA, we have been able to identify candidate genes that might mediate the core myogenic features of KD/SBMA. Keywords: Gene expression in transgenic mice and disease state analysis We used microarray (38.5K oligo mouse array, which contain 35,302 of 70mer oligonucleotide probes largely derived from constitutively expressed exons and 3,482 of controls) to analyze gene expression in limb muscles of transgenic mice. Three mouse models of KD/SBMA were used: HSA-AR, AR113Q knock-in and AR97Q. HSA-AR transgenic male mice (n=5) and their WT brothers (n=8, all mice were 110-130 days of age) were used in this experiment. ARQ113-Knock In males (n=3, 3-4 months of age), and transgenic AR97Q males and WT brothers (n= 6 of each) were used in this study. For both HSA-AR and AR113Q samples, the log2 ratio of experimental samples (Cy5) and reference RNA(Cy3) was obtained, and log2 ratios from mutant samples were then subtracted from log2 ratios from WT controls. AR97Q males (Cy5) were simply compared with their WT brothers (Cy3) using a log2 ratio, rather than being first compared with reference RNA.
2010-10-12 | E-GEOD-10190 | biostudies-arrayexpress