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Gene expression changes in Dhcr7 knockout brain, lung and liver at E18.5 compared to wild-type embryos

ABSTRACT: 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.

ORGANISM(S): Mus musculus

PROVIDER: GSE39811 | GEO | 2012/08/02

SECONDARY ACCESSION(S): PRJNA171752

REPOSITORIES: GEO

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Gene expression changes in Dhcr7 knockout brain, lung and liver at E18.5 compared to wild-type embryos

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

The human cholesterogenic enzymes DHCR14 and LBR are differentially regulated transcriptionally and post-translationally

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

Expression data from control and Smith-Lemli-Opitz syndrome patient-derived iPS cells - comparison of cholesterol deficient and cholesterol rich culture

2015-09-18 | GSE61203 | GEO

Expression data from control and Smith-Lemli-Opitz syndrome patient-derived iPS cells - comparison of cholesterol deficient and cholesterol rich culture

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

Temporal gene expression changes and affected pathways in neurodevelopment of a mouse model of Smith-Lemli-Opitz syndrome

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

Denunded HUVEC/HUASMC spheroids vs. HUASMC spheroids

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

The effects of liver specific deletion of Dhcr7 on gene expression

Project description:Smith-Lemli-Opitz Syndrome (SLOS) is a developmental disorder caused by autosomal recessive mutations in the Dhcr7 gene. SLOS patients present clinically with multiple dysmorphologies, neurological, behavioral and cognitive defects, and demonstrate impaired cholesterol biosynthesis resulting in markedly elevated 7-DHC in all bodily tissues and fluids. Previous rodent models of SLOS suffered from neonatal mortality or variation in the biochemical phenotype over time. We generated a viable murine model bearing a conditional flosed allele of the Dhcr7 gene, and validated it by generating a mice with liver-specific deletion of Dhcr7 by breeding with a strain expressing Cre recombinase driven by an albumin promoter . These mice demonstrated elevated circulatory and liver 7-DHC levels, but phenotypic characterization of the knockout mice revealed no significant changes in viability, fertility, growth curves, liver architecture, hepatic triglyceride secretion, and parameters of systemic glucose homeostasis. Investigation in to changes in the liver transcriptome were investigated withe RNAseq, and identified enrichment in various pathways, including steroid hormone biosynthesis and various cell signaling and metabolism pathways. Most notably missing from the list are the genes related to cholesterol biosynthesis. Generation of this Dhcr7 conditional knockout model will allow for better studies into the post natal effects of blocking cholesterol biosynthesis, accumulation of 7-DHC, and the role of DHCR7 in specific tissues.

2020-09-04 | GSE146523 | GEO

Dietary cholesterol supplementation to a plant-based diet for Atlantic salmon

Project description:The study evaluated effects of dietary cholesterol (1.5%) in Atlantic salmon fed a plant based diet for 77 days. Cholesterol supplementation did not affect growth or organ weights of Atlantic salmon, but promoted induction of cholesterol and plant sterol efflux in the intestine, whereas sterol uptake was suppressed. Microarray analyses in the liver indicated decreased cholesterol biosynthesis and enhanced conversion to bile acids. The marked effect of cholesterol on bile acid synthesis suggests that dietary cholesterol can be used to stimulate bile acid synthesis in fish. The study clearly demonstrated how Atlantic salmon adjusted metabolic functions in response to the dietary load of cholesterol, and has expanded our understanding of sterol metabolism and turnover that adds to the knowledge of these processes in fish. Atlantic salmon received feeds based on plant ingredients with (CH) and without (K) supplementation of cholesterol. Liver samples were collected after 77 days. Five individuals from each group were analyzed with microarrays, pooled liver sample of salmon fed with commerical fish meal based feed was used as a reference.

2013-10-31 | E-GEOD-51887 | biostudies-arrayexpress

Dietary supplementation to a plant-based diet for Atlantic salmon

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2013-10-31 | GSE51887 | GEO

p53 transcriptionally regulates SQLE to modulate cholesterol synthesis and tumor growth

Project description:Cholesterol is essential for membrane biogenesis, cell proliferation and differentiation. The role of cholesterol in cancer development and the regulation of cholesterol synthesis are still under active investigation. Here we show that under normal-sterol conditions，p53 directly represses the expression of SQLE, a rate-limiting and the first oxygenation enzyme in cholesterol synthesis，in a SREBP2-independent manner. Through transcriptional downregulation of SQLE, p53 represses cholesterol production in vivo and in vitro, leading to tumor growth suppression. Inhibition of SQLE using small interfering RNA (siRNA) or terbinafine (a SQLE inhibitor) reverses the increased cell proliferation caused by p53 deficiency. Conversely, SQLE overexpression or cholesterol addition promotes cell proliferation, particularly in p53 wild-type cells. More importantly, pharmacological inhibition or shRNA-mediated silencing of SQLE restricts nonalcoholic fatty liver disease (NAFLD) -induced liver tumorigenesis in p53 knockout mice. Therefore, our findings reveal a role for p53 in regulating SQLE and cholesterol biosynthesis, and further demonstrate that downregulation of SQLE is critical for p53-mediated tumor suppression.

2021-07-18 | GSE176112 | GEO

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