Defects in CYB5A and CYB5B Impact Sterol C4 Demethylation in Cholesterol Biosynthesis and Demonstrate Regulatory Roles of Dimethyl Sterols
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1168488 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR30872747_1.fastq.gz | Fastqsanger.gz | |||
| SRR30872747_2.fastq.gz | Fastqsanger.gz | |||
| SRR30872748_1.fastq.gz | Fastqsanger.gz | |||
| SRR30872748_2.fastq.gz | Fastqsanger.gz | |||
| SRR30872749_1.fastq.gz | Fastqsanger.gz |
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Project description:The model ciliate Tetrahymena thermophila satisfies its growth using triterpenoid alcohols, mainly tetrahymanol, as a surrogate of sterols. When sterols are present in the environment, T. thermophila efficiently incorporates and modifies them. T. thermophila can modify exogenous sterols by desaturation at positions C5(6), C7(8) and C22(23), and also by de-ethylation of C24. Three out of four of the enzymes involved in the sterol modification pathway were previously described by our group. However, identification of the sterol C22 desaturase remained elusive, as well as other basic aspects of this metabolism. To get more insights into this peculiar metabolism we here perform a whole transcriptome analysis of T. thermophila in response to exogenous cholesterol. We found 356 T. thermophila genes to be differentially expressed after supplementation with cholesterol for two hours. Among those genes that were upregulated under our experimental conditions, we identified two genes belonging to the long-spaced family of desaturases that we propose as putative sterol C22 desaturases. Moreover, we determined that the inhibition of tetrahymanol synthesis after sensing exogenous cholesterol occurs by a transcriptional downregulation of genes involved in squalene synthesis and cyclization. Finally, we also identified several uncharacterized genes that can be putatively involved in sterols transport and signaling.
2019-11-05 | GSE130336 | GEO
Project description:Liposomal amphotericin B is an important frontline drug for the treatment of visceral leishmaniasis, a neglected disease of poverty. The mechanism of action of amphotericin B (AmB) is thought to involve interaction with ergosterol and other ergostane sterols, resulting in disruption of the integrity and key functions of the plasma membrane. Emergence of clinically refractory isolates of L. donovani and L. infantum is an ongoing issue and knowledge of potential resistance mechanisms can help to alleviate this problem. Here we report the characterisation of four independently selected L. donovani clones that are resistant to AmB. Whole genome sequencing revealed that in three of the moderately resistant clones, resistance was due solely to the deletion of a gene encoding C24-sterol methyltransferase (SMT1). The fourth, hyper-resistant resistant clone (>60-fold) was found to have a 24 bp deletion in both alleles of a gene encoding a putative cytochrome P450 reductase (P450R1). Metabolic profiling indicated these parasites were virtually devoid of ergosterol (0.2% versus 18% of total sterols in wild-type) and had a marked accumulation of 14-methylfecosterol (75% versus 0.1% of total sterols in wild-type) and other 14-alpha methylcholestanes. These are substrates for sterol 14-alpha demethylase (CYP51) suggesting that this enzyme is a bona fide P450R specifically involved in electron transfer from NADPH to CYP51 during catalysis. Deletion of P450R1 in wild-type cells phenocopied the metabolic changes observed in our AmB hyper-resistant clone as well as in CYP51 nulls. Likewise, addition of a wild type P450R1 gene restored sterol profiles to wild type. Our studies indicate that P450R1 is essential for L. donovani amastigote viability, thus loss of this gene is unlikely to be a driver of clinical resistance. Nevertheless, investigating the mechanisms underpinning AmB resistance in these cells provided insights that refine our understanding of the L. donovani sterol biosynthetic pathway.
2024-06-21 | PXD052472 | Pride
Project description:HepG2 cell line CRISPR-Cas9 generated Knock-out in 4 cholesterol synthesis gene: CYP51, DHCR24, SC5D and HSD17B7 Excess of cholesterol associates with a variety of diseases so its synthesis must be under tight homeostatic control. The early part of cholesterol synthesis with rate-limiting HMGCR and SQLE steps is proceeded by the sterol part where numerous non-polar sterols with poorly defined biological functions are produced. To illuminate their role we developed knockouts (KO) for the consecutive enzymes that metabolize sterols towards cholesterol CYP51A1, DHCR24, SC5D resulted in the accumulation of specific set of sterols in each KO cell. Despite that, we targeted three steps of the cholesterol synthesis housekeeping pathway, the overlap of de-regulated genes was only 9%, suggesting that each set of sterols modulated the hepatic cell transcriptome uniquely. Lanosterol and 24,25-dihydrolanosterol, but not other non-polar sterols, provoked higher cell proliferation, cell cycle changes, and upregulation of metabolic pathways and transcription factors (TFs) associated with cancer progression and immune response like NFKB, SMAD, ESR1 and highly elevated LEF1 a protein from WNT signalling. In contrast, lathosterol and desmosterol caused slower proliferation and apoptosis promotion, through TFs like HNF1A and E2F. We were able to show how sterols from early part of synthesis can promote cell proliferation as sterols from end of synthesis suppress proliferation. These findings challenge the current dogma that sterols produced during cholesterol synthesis have similar biological functions
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Project description:Xanthophyllomyces dendrorhous is a basidiomycete yeast that produces carotenoids, mainly astaxanthin. Astaxanthin is an organic pigment of commercial interest due to its antioxidant and coloring properties. X. dendrorhous has a functional Sterol Regulatory Element-Binding Protein (SREBP) pathway, and the Sre1 protein is the SREBP homolog in this yeast. However, how Sre1 is promoting the biosynthesis of sterols and carotenoids in X. dendrorhous is unknown. In this work, comparative RNA-seq analysis between modified X. dendrorhous strains that have an active Sre1 protein and the wild-type was performed to identify Sre1-dependent genes. In addition, Sre1 direct target genes were identified through chromatin immunoprecipitation combined with lambda exonuclease digestion (ChIP-exo) assays. SRE motifs were detected in the promoter regions of several Sre1 direct target genes and were consistent with the SREs described in other yeast species. Sre1 directly regulates genes related to ergosterol biosynthesis as well as genes related to the mevalonate pathway, which synthesizes the building blocks of isoprenoids, including carotenoids. Two carotenogenic genes, crtE and crtR, were also identified as Sre1 direct target genes. Thus, carotenogenesis in X. dendrorhous is regulated by Sre1 through the regulation of the mevalonate pathway and the regulation of the crtE and crtR genes. As the crtR gene encodes a cytochrome P450 reductase, Sre1 regulates pathways that include cytochrome P450 enzymes, such as the biosynthesis of carotenoids and sterols. These results demonstrate that Sre1 is a sterol master regulator that is conserved in X. dendrorhous.
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2012-06-13 | E-GEOD-38699 | biostudies-arrayexpress
Project description:Sterols are essential nutrients for insects because, in contrast to mammals, no insect (or arthropod for that matter) can synthesize sterols de novo. Cholesterol is the most common sterol in insects, but it is not found in plants in large quantities; plant-feeding insects typically generate their cholesterol by metabolizing phytosterols. However, different plants species can contain different types of phytosterols, and some phytosterols are not readily converted to cholesterol. In this study we examined, using artificial diets containing single sterols, how typical (cholesterol and stigmasterol) and atypical (cholestanol and cholestanone) sterols/steroids affect the performance of a generalist caterpillar (Helicoverpa zea), restricting this analysis to midgut tissue because this is where sterol/steroid absorption occurs, and the midgut is the putative site of dietary sterol/steroid metabolism. In general, H. zea performed best on the cholesterol and stigmasterol treatments; performance was reduced on cholestanol, and was very poor on cholestanone. We compared the transcript profiles of larval guts in response to differentially suitable sterols, using the optimal sterol, cholesterol, as a control, using a two-color reference design microarray experiment. Midgut gene expression patterns differed between the treatments; relative to cholesterol, differences were lowest on the stigmasterol treatment, intermediate on the cholestanol treatment, and greatest on the cholestanone treatment.
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