The effects of liver specific deletion of Dhcr7 on gene expression
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE146523 | GEO | 2020/09/04
REPOSITORIES: GEO
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Project description:7-dehydrocholesterol reductase catalyzes the reduction of 7-dehydrocholesterol to cholesterol. In Smith-Lemli-Opitz syndrome, mutations in DHCR7 prevents this conversion. We have found iPS cells derived from SLOS patients exhibit accelerated differentiation under cholesterol poor conditions. In this dataset, we include expression data obtained from comparision of a control iPS cell line (BJ) and a SLOS iPS cell line (A2). Cell line gene expression was compared in cholesterol rich conditions where the SLOS phenotype is suppressed. Cholesterol deficient culture of control and SLOS iPS cells demonstrated enhanced differentiation of SLOS cells over 7 days. These data are used to obtain 308 genes that are differentially expressed upon cholesterol deficient culture. time-course expression data obtained from control and SLOS patient iPS cells after transfer from cholesterol rich to cholesterol deficient culture.
2015-09-18 | GSE61203 | GEO
Project description:7-dehydrocholesterol reductase catalyzes the reduction of 7-dehydrocholesterol to cholesterol. In Smith-Lemli-Opitz syndrome, mutations in DHCR7 prevents this conversion. We have found iPS cells derived from SLOS patients exhibit accelerated differentiation under cholesterol poor conditions. In this dataset, we include expression data obtained from comparision of a control iPS cell line (BJ) and a SLOS iPS cell line (A2). Cell line gene expression was compared in cholesterol rich conditions where the SLOS phenotype is suppressed. Cholesterol deficient culture of control and SLOS iPS cells demonstrated enhanced differentiation of SLOS cells over 7 days. These data are used to obtain 308 genes that are differentially expressed upon cholesterol deficient culture. time-course expression data obtained from control and SLOS patient iPS cells after transfer from cholesterol rich to cholesterol deficient culture. 48 total RNA samples were isolated and hybridized on Affymetrix arrays. We generated the following pairwise comparisons using Partek: BJ 0hr vs A2 0hr; BJ 2Day vs A2 2Day; BJ 3Day vs A2 3Day; BJ 4Day vs A2 4Day; BJ 5Day vs A2 5Day; BJ 7Day vs A2 7Day. Genes with an FDR≤10% and a fold-change ≥3 were identified as significantly different. We also performed pairwise comparison of BJ and A2 samples within each cell line between subsequent isolations (i.e. BJ 0hr vs BJ 2Day; A2 3Day vs A2 4Day; etc.)
2015-09-18 | E-GEOD-61203 | biostudies-arrayexpress
Project description:Smith-Lemli-Opitz syndrome is an autosomal recessive disorder that arises from mutations in the gene DHCR7, which encodes the terminal enzyme of cholesterol biosynthesis, leading to decreased production of cholesterol and accumulation of the cholesterol precursor, 7-dehydrocholesterol, and its oxysterol metabolites. The disorder displays a wide range of neurodevelopmental defects, intellectual disability and behavioral problems. However, an in-depth study on the temporal changes of gene expression in the developing brains of SLOS mice has not been done before. In this work, we carried out the transcriptomic analysis of whole brains from WT and Dhcr7-KO mice at four time points through postnatal day 0. First, we observed the expected downregulation of the Dhcr7 gene in the Dhcr7-KO mouse model, as well as gene expression changes of several other genes involved in cholesterol biosynthesis throughout all time points. Pathway and GO term enrichment analyses revealed affected signaling pathways and biological processes that were shared amongst time points and unique to individual time points. Specifically, the pathways important for embryonic development, including Hippo, Wnt, and TGF-β signaling pathways are the most significantly affected at the earliest time point, E12.5. Additionally, neurogenesis-related GO terms were enriched in earlier time points, consistent with the timing of development. Conversely, pathways related to synaptogenesis, which occurs later in development compared to neurogenesis, are significantly affected at the later time points, E16.5 and PND0, including the cholinergic, glutamatergic, and GABAergic synapses. The impact of these transcriptomic changes and enriched pathways is discussed in the context of known biological phenotypes of SLOS.
2024-02-15 | GSE247566 | GEO
Project description:Altered metabolic pathways that cancer cells reply on for survival and growth are useful targets for therapeutic intervention. Here we show that de novo cholesterol biosynthesis pathways in head and neck squamous cell carcinoma (HNSCC) are highly increased to support tumor survival. Transcriptomics profiling of tumor tissues isolated from patients with HNSCC identified steroid/cholesterol metabolism as the most significantly altered metabolic pathways when compared with paired normal tissues. Disruption of two key enzymes 7-dehydrocholesterol reductase (DHCR7) and 24-dehydrocholesterol reductase (DHCR24) that are elevated and involved in de novo cholesterol biosynthesis using genetic approach or small inhibitory molecules (AY9944 or triparanol) results in increased apoptosis of HNSCC cells despite of replenished cholesterol. Metabolic signatures of cholesterol identified accumulated intracellular 7-dehydrocholesterol (7-DHC), a substrate of DHCR7, when either DHCR7 or DHCR24 is inhibited. Further exogenous 7-DHC supplementation decreased cancer cell viability causing cell death by inducing ER stress through eIF2alpha and IRE1 phosphorylation in HNSCC cells. This study revealed that HNSCC manages ER stresses via elevated cholesterol biosynthesis in order to remove 7-DHC for cancer viability. Our finding suggests that the metabolic intermediates in de novo cholesterol synthesis are metabolic vulnerability of HNSCC to induce ER stress and apoptosis as a potential therapeutic strategy. This study provides the evidence of direct link between the cholesterol metabolism and ER stress for cancer cell viability, suggesting metabolic vulnerability of HNSCC.
2025-04-01 | GSE285603 | GEO
Project description:RELEVANCE: Smith-Lemli-Opitz syndrome (SLOS) is a human disease caused by mutations in the gene coding for the enzyme DHCR7 (7-dehydrocholesterol (7DHC) reductase), which catalyzes the final step of cholesterol biosynthesis. Accumulated 7DHC in tissues and body fluids of SLOS patients gives rise to numerous oxidation products (oxysterols) in situ, some of which are cytotoxic, and which may contribute to the pathophysiology of SLOS. The SLOS phenotype is broad, ranging from death in utero to viable individuals with malformations and malfunctions in numerous organ systems and tissues, including neurological and cognitive defects. The latter presentations suggest that impaired cholesterol synthesis, in particular the generation of toxic oxysterols, has a deleterious impact on the morphogenesis and viability of neurons in the CNS. In a rat model of SLOS (using a small molecule inhibitor of DHCR7), the loss of photoreceptors was also documented, distinct from the continuous viability of other retinal neurons and supporting cells, and this selective cell death was recapitulated in vitro using 661W cells (an immortalized line derived from mouse cones) incubated with purified 7DHC-derived, SLOS-associated oxysterols. Upon exposure to these compounds, cell viability assay results for 661W showed one to two orders of magnitude higher sensitivity with respect to efficacy and potency, and also an accelerated time frame for cell death, compared to retinal Mueller glia and retinal pigment epithelial cells. These findings inspired questions as to the molecular mechanisms underlying oxysterol-induced neuronal cell death. Therefore, we characterized differential gene expression associated with processes and pathways induced by oxysterol treatments, first, to provide insights regarding cell death and dysfunction, not only in SLOS, but also extended to other neurodegenerative diseases (including those affecting the retina), and second, to identify cellular protective responses, with the expectation that these findings would suggest possibilities for future prevention and treatment of neurological disease and damage. INTENT: Generate gene expression array profiles of 661W cells following exposure to either of two oxysterols. The oxysterols are employed at doses already determined to exert full cytotoxicity by 24 hours incubation time; however, for the purposes of the array, stop incubations for each oxysterol at time points preceding global cell death, to harvest still-intact RNA from a majority of cells that have maintained membrane integrity, and are also displaying microscopically observable indications of morphological response to the oxysterol treatments already known to precede the demise of the cells. Therefore, the samples are expected to manifest transcriptomes emblematic of gene expression changes in response to the oxysterols. These changes should fit patterns that correlate with pathways and processes associated with cellular damage and regulated cell death, or with cell survival/protective and repair mechanisms (with expected overlap of the two opposing scenarios). As a negative control, a separate set of replicates are incubated with cholesterol under conditions having no impact on cell viability (23 hours, at a (non-physiological) concentration intermediate between that of the two oxysterols). To identify differentially expressed genes, individual array probe set data for either oxysterol and for cholesterol are matched with those from cells incubated with a vehicle control (for 24 hours), for computing “-fold change” in expression and statistical significance of expression differences. EXPERIMENTAL WORKFLOW: 1) 661W cells were seeded in 100-mm cell culture-treated dishes at a density permitting proliferation to subconfluence, allowing cells to retain neurite-like extensions; includes overnight adaptation to a simplified incubation medium devoid of most growth factors and reagents supporting antioxidant activity. 2) Cells were exposed for a predetermined time period to a single concentration of: i) either of two different oxysterols (EPCD, an endoperoxide specific to SLOS, or 7-ketocholesterol); ii) cholesterol; or iii) vehicle control. 3) Total RNA was harvested, from each triplicate sample representing the above treatments, according to the RNeasy Plus minikit protocol (Qiagen). 4) Final sample preparation (amplification, labeling, fragmentation of cRNA) was carried out a core facility following Affymetrix specifications and protocols. 5) Hybridized chips were scanned to generate raw intensity data for further analysis.
2021-03-20 | E-MTAB-10055 | biostudies-arrayexpress
Project description:<p>Smith-Lemli-Opitz syndrome (SLOS) is a disorder of cholesterol production by the body. It is caused by changes in the DHCR7 gene, which is the blueprint for an enzyme called 7-dehydrocholesterol- delta7-reductase. This enzyme is necessary for the production of cholesterol by all cells in the body. People with SLOS often have malformations of major organs, slow growth, feeding difficulties and intellectual disability or learning problems.</p> <p>Because patients with SLOS cannot make enough cholesterol, it has been proposed that cholesterol supplementation (either with egg yolk or liquid suspensions of cholesterol) could help improve the symptoms of the disease. However, despite the widespread use of cholesterol supplementation, it is still not known whether it works or not. The study will try to provide an answer to this question by studying the disease and its progression while patients are receiving cholesterol.</p> <p>The clinical features of SLOS are thought to be related to low cholesterol and buildup of toxic cholesterol precursors (substances from which cholesterol is formed). But how exactly low cholesterol and toxic precursors contribute to the disease is poorly understood. This knowledge is critically important because it should help discover new therapeutic targets and develop treatments of the disease in the long run. The study will try to fill this gap with a comprehensive clinical and biochemical testing of the study participants over the course of several years.</p> <p>Last, a limitation of previous SLOS research studies has been their low number of participants. This is understandable because SLOS is a rare diseases and few research groups are working on it. However, in order to fully understand the disease, researchers need to study as many patients as possible. This study is unique in that it is run by a network of several highly specialized clinical research sites across the country. Having several sites involved increases the researcher's ability to recruit and study large number of patients, and centralize patients' information in a comprehensive SLOS clinical registry. This registry will be key to identify markers for diagnostic testing, screening and measuring outcomes in future studies of treatment.</p> <p>The purpose of this study is to learn as much as possible about Smith-Lemli-Opitz Syndrome (SLOS) by following a large group of affected children and adults over time. In this study, we will measure cholesterol and other similar chemicals in blood and urine, evaluate development and behavior, do limited medical evaluation, and carry out brain imaging studies.This study will help researchers: <ul> <li>learn more about what causes SLOS and how SLOS changes with age,</li> <li>note differences in features of SLOS among those affected,</li> <li>evaluate the effect of giving extra cholesterol in this condition, and</li> <li>develop ways to evaluate whether treatments developed in the future will be helpful.</li> </ul> </p>
| phs001430 | dbGaP
Project description:The genetic defect underlying the human Smith-Lemli-Opitz dysmorphological disorder is loss-of-function mutations affecting the cholesterol synthesis enzyme dehydrocholesterol delta7 reductase, DHCR7. Dhcr7 knockout mice recapitulate the biochemical characteristics, but all knockout pups die within 14h of birth. Tissues of knockout mice accumulate the precursor sterol, 7-dehydrocholesterol, and show reduced levels of cholesterol (J. Clin. Invest. (2001) 108: 905-915). We compared the global gene expression changes in lung, liver and brain from knockout mice to those seen from organs harvested from same-pregnancy wild-type embryos, harvested before birth (E18.5). Since the P0 knockout pups die, we expected that there would be significant changes in gene expression between knockout and wild-type organs, and further comparing the altered genes in common to brain, lung and liver would point to a common mechanistic pathway where disruption of normal sterol synthesis in all cells leads to pathophysiology. Remarkably, these data show that the global gene expression between knockout and wild-type organs is hardly altered, despite the complete loss of cholesterol synthesis. There are so few genes that are altered, and furthermore, those that are altered are very limited in sharing similarities in all three tissues. This suggests that disorganized gene expression is not the cause of the early neonatal lethality. Dhcr7+/- females were mated with Dhcr+/- males, and timed pregnancy obtained. At E18.5, pregnant dams were sacrificed, and embryos harvested, organs removed and RNA extracted, and all embryos were genotyped. Matching wild-type and knockout embryos were taken from each pregnancy, and two females yielded all genotypes used herein.
2012-08-01 | E-GEOD-39811 | biostudies-arrayexpress
Project description:The genetic defect underlying the human Smith-Lemli-Opitz dysmorphological disorder is loss-of-function mutations affecting the cholesterol synthesis enzyme dehydrocholesterol delta7 reductase, DHCR7. Dhcr7 knockout mice recapitulate the biochemical characteristics, but all knockout pups die within 14h of birth. Tissues of knockout mice accumulate the precursor sterol, 7-dehydrocholesterol, and show reduced levels of cholesterol (J. Clin. Invest. (2001) 108: 905-915). We compared the global gene expression changes in lung, liver and brain from knockout mice to those seen from organs harvested from same-pregnancy wild-type embryos, harvested before birth (E18.5). Since the P0 knockout pups die, we expected that there would be significant changes in gene expression between knockout and wild-type organs, and further comparing the altered genes in common to brain, lung and liver would point to a common mechanistic pathway where disruption of normal sterol synthesis in all cells leads to pathophysiology. Remarkably, these data show that the global gene expression between knockout and wild-type organs is hardly altered, despite the complete loss of cholesterol synthesis. There are so few genes that are altered, and furthermore, those that are altered are very limited in sharing similarities in all three tissues. This suggests that disorganized gene expression is not the cause of the early neonatal lethality.
2012-08-02 | GSE39811 | GEO
Project description:Cholesterol synthesis is a tightly regulated process, both transcriptionally and post-translationally. Transcriptional control of cholesterol synthesis is relatively well understood. However, of the ~20 enzymes in cholesterol biosynthesis, post-translational regulation has only been examined for a small number. Three of the four sterol reductases, DHCR7, DHCR14 and LBR, share evolutionary ties with a high level of sequence homology and predicted structural homology. Despite their homology and that they uniquely share the same 14 reductase activity in cholesterol biosynthesis, little is known about the post-translational regulation of DHCR14 and LBR. Using CHO-7 cells stably expressing epitope tagged DHCR14 or LBR we investigated the post-translational regulation of these enzymes. We found that DHCR14 and LBR undergo differential post translational regulation, with DHCR14 being rapidly turned over, triggered by cholesterol and other sterol intermediates while LBR remained stable. DHCR14 is degraded via the ubiquitin-proteasome system and we identified several DHCR14 and DHCR7 putative interaction partners including the E3 ligase WWP2, which plays a role in the basal and cholesterol-mediated regulation of DHCR14. Interestingly, we found that gene expression across an array of human tissues showed that the C14-SRs gene expression is negatively related; one enzyme or the other tends to be predominately expressed in each tissue. Overall, our findings indicate that while LBR tends to be the constitutively active C14-SR, DHCR14 levels are tuneable, responding to the local cellular demands for cholesterol.
2020-01-15 | PXD016417 | Pride
Project description:Here, we investigated changes of the VSMC transcriptome by utilizing 3D human vascular organoids organized as a core of VSMCs enclosed by a monolayer of ECs. Unbiased microarray-based analyses indicated that interaction with ECs for 48 hours down-regulates the VSMC expression of genes controlling rate-limiting steps of the cholesterol biosynthesis such as HMGCR, HMGCS1, DHCR24 and DHCR7. Protein analyses revealed a decrease in the abundance of 24-dehydrocholesterol reductase and lower cholesterol levels in VSMCs co-cultured with ECs. On the functional level, the blockade of the DHCR24 activity impaired spreading, migration and proliferation of VSMCs. Collectively, these findings indicate that ECs have the capacity to instruct VSMCs to shut down the expression of DHCR24 thereby limiting their capacity for cholesterol biosynthesis which may support their functional steady state.
2020-12-17 | GSE156274 | GEO