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Dietary sterols/steroids and the generalist caterpillar Helicoverpa zea: physiology, biochemistry and midgut gene expression

ABSTRACT: 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.

ORGANISM(S): Helicoverpa armigera Helicoverpa zea

PROVIDER: GSE38699 | GEO | 2012/06/14

SECONDARY ACCESSION(S): PRJNA168508

REPOSITORIES: GEO

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Dietary sterols/steroids and the generalist caterpillar Helicoverpa zea: physiology, biochemistry and midgut gene expression

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. Transcriptional profiling comparing Helicoverpa zea gut tissue from third instar larvae exposed to four different dietary sterols, namely Cholesterol (CON), Cholestanol (ChStanol), Cholestan-3-one (Ch3one) and Stigmasterol (Stigma). Two-color reference design. Biological replicates: 4 (5 individuals per replicate). 12 samples total.

2012-06-13 | E-GEOD-38699 | biostudies-arrayexpress

RNA-seq of mutant Mycobacterium neoaurum producing steroid intermediates compared with wild-type strain

Project description:Mycobacterium neoaurum (Mn), an efficient sterol consumer, has been modified to transform sterols to produce valuable steroid intermediates, which can be widely used as precursors in the synthesis of steroid hormones.To deepen our understand of the underlying mechanisms of Mn to the in vitro and in vivo environment during growth on a critical carbon source of sterol and accumulation of valuable steroid intermediates, transcriptome studies were performed to characterize the differences between wide-type Mn and various mutant Mn strains for steroid accumulation. Totally, five Mn strains were investigated, including wide-type Mn ATCC25795 cultured without (Mn-C) and with sterol addition (Mn-CC), mutant Mn ATCC25795 strains producing 9OHAD (Mn-9OHAD), ADD (Mn-ADD), and 1,4-HBC (Mn-HBC), respectively.

2018-05-26 | E-MTAB-6789 | biostudies-arrayexpress

Transcriptional response of Tetrahymena thermophila to exogenous cholesterol

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

Helicoverpa zea

Project description:Dietary sterols/steroids and the generalist caterpillar Helicoverpa zea: physiology, biochemistry and midgut gene expression

| PRJNA168508 | ENA

SREBP1c and mock virus expression profiles in AG01518 human fibroblasts

Project description:Sterol-regulatory element binding proteins (SREBP) control the expression of most genes involved in fatty acid and cholesterol metabolism. In this report, using microarrays, we showed that SREBP1 also induced genes unrelated to lipid biosynthesis, such as heme oxygenase 1 (HMOX1), the phosphatidylinositol-3 kinase regulatory subunit p55-gamma, synaptic vesicle glycoprotein 2A (SV2A) and COTE1 (C1orf2). These genes were regulated by infection with adenoviruses encoding active SREBP1, sterols, statins and growth factors, as one would expect from SREBP1 target genes Keywords: treatment comparaison

2007-04-26 | GSE6877 | GEO

Zinc finger transcription factors displaced SREBP proteins as the major sterol regulators during Saccharomycotina evolution

Project description:All but a few eukaryotes die without oxygen and respond dynamically to changes in the level of oxygen available to them. One ancient oxygen-requiring biochemical pathway in eukaryotes is the pathway for the biosynthesis of sterols, leading to cholesterol in animals and ergosterol in fungi. Mutations in this pathway are a frequent cause of azole drug resistance in pathogenic fungi. The regulatory mechanism for the sterol pathway is also widely conserved between animals and fungi and is centred on a transcription activator, SREBP, that forms part of a sterol-sensing complex. However, in one group of yeasts – the Saccharomycotina, which includes the major pathogen Candida albicans – control of the sterol pathway has been taken over by an unrelated regulatory protein, Upc2. We show here by analysis of the yeast Yarrowia lipolytica that the evolutionary switch from SREBP to Upc2 was a two-step process in which Upc2 appeared in an ancestor of Saccharomycotina, and SREBP subsequently degenerated and lost its sterol-regulatory function while retaining an ancient role in filamentation.

2013-11-19 | GSE47433 | GEO

A PhotoClick cholesterol-based quantitative proteomics screen for cytoplasmic sterol binding proteins in Saccharomyces cerevisiae

Project description:Ergosterol is a prominent component of the yeast plasma membrane and essential for yeast cell viability. It is synthesized in the endoplasmic reticulum and transported to the plasma membrane by non-vesicular mechanisms requiring carrier proteins. Oxysterol binding protein homologues and yeast StARkin proteins have been proposed to function as sterol carriers. Although many of these proteins are capable of transporting sterols between synthetic lipid vesicles in vitro, they are not essential for ergosterol transport in cells, indicating that they may be functionally redundant with each other or with additional - as yet unidentified - sterol carriers. To address this point we hypothesized that sterol transport proteins are also sterol binding proteins (SBPs), and used an in vitro chemo-proteomic strategy to identify all cytosolic SBPs. We generated a cytosol fraction enriched in SBPs and captured the proteins with a photoreactive clickable cholesterol analog. Quantitative proteomics of the captured proteins identified 342 putative SBPs. Analysis of these identified proteins based on their annotated function, reported drug phenotypes, interactions with proteins regulating lipid metabolism, gene ontology, and presence of mammalian orthologs revealed a subset of 62 characterized and nine uncharacterized candidates. Five of the uncharacterized proteins play a role in maintaining plasma membrane integrity as their absence affects the ability of cells to grow in the presence of nystatin or myriocin. We anticipate that the dataset reported here will be a comprehensive resource for functional analysis of sterol binding/transport proteins and provide insights into novel aspects of non-vesicular sterol trafficking.

2019-11-25 | PXD014555 | Pride

Saturated fat diet induces transintestinal cholesterol excretion in mice

Project description:Intake and absorption of cholesterol (the latter determined by double labeled cholesterol methodology) were nearly unchanged in mice fed the saturated fat diet, but the fecal excretion of neutral sterols (i.e. cholesterol and its microbial conversion products) was increased compared with control diet(+80%; p<0.01). The saturated fat diet did neither significantly affect biliary cholesterol secretion nor intestinal cholesterol absorption (49% vs. 65% in controls, double labeled water methodology, p>0.1). Thus, the increased fecal neutral sterol excretion was primarily due to increased net transintestinal cholesterol excretion (+89% versus control; p<0.05). Since a major fraction of TICE cholesterol absorption is normally reabsorbed (J Lipid Res 2019 Sep;60(9):1562-1572), the increased fecal cholesterol excretion could be due to more transintestinal excretion of cholesterol into the intestinal lumen and/or to its decreased reabsorption. The saturated fat diet increased jejunal expression of genes involved in cholesterol synthesis (Srebf2 and target genes), but did not affect whole body de novo cholesterol synthesis. Conclusion This proof-of-principle study shows that increasing the saturation of the dietary fat can stimulate fecal cholesterol excretion. Individual components of saturated fat diets are to be explored to address the responsible molecular mechanisms

2021-02-01 | GSE37097 | GEO

Zinc finger transcription factors displaced SREBP proteins as the major sterol regulators during Saccharomycotina evolution

Project description:All but a few eukaryotes die without oxygen and respond dynamically to changes in the level of oxygen available to them. One ancient oxygen-requiring biochemical pathway in eukaryotes is the pathway for the biosynthesis of sterols, leading to cholesterol in animals and ergosterol in fungi. Mutations in this pathway are a frequent cause of azole drug resistance in pathogenic fungi. The regulatory mechanism for the sterol pathway is also widely conserved between animals and fungi and is centred on a transcription activator, SREBP, that forms part of a sterol-sensing complex. However, in one group of yeasts M-bM-^@M-^S the Saccharomycotina, which includes the major pathogen Candida albicans M-bM-^@M-^S control of the sterol pathway has been taken over by an unrelated regulatory protein, Upc2. We show here by analysis of the yeast Yarrowia lipolytica that the evolutionary switch from SREBP to Upc2 was a two-step process in which Upc2 appeared in an ancestor of Saccharomycotina, and SREBP subsequently degenerated and lost its sterol-regulatory function while retaining an ancient role in filamentation. RNA was isolated from Y. lipolytica wildtype (JMY2900) in normoxia (21% oxygen, 4 biological replicates), wildtype (JMY2900) in hypoxia (1% oxygen, 5 biological replicates), upc2 deletion (SMY2) in hypoxia (1% oxygen, 3 biological replicates), and from sre1 (SMY5, SMY8) deletion in hypoxia (1% oxygen, 2 biological replicates). Gene expression was determined using strand-specific RNA-seq.

2013-11-19 | E-GEOD-47433 | biostudies-arrayexpress

Thermal proteome profiling reveals distinct target selectivity for differentially oxidized oxysterols

Project description:The dataset contains mass spectrometric raw data from Thermal Proteomic Profiling experiments aimed to identify the protein targets of three A- and B-ring oxidized sterols (cholestane-3beta,5alfa,6beta-triol (CT), 7keto-cholesterol (7-KC), 4beta-hydroxycholesterol (4beta-HC) ) and a side-chain oxidized sterol (25-hydroxycholesterol (25-HC)). The dataset comprises the raw data for the 4 different oxysterols, measured on both oxysterol (compound) and DMSO (vehicle), each collected in 28 fractions. The experiments were performed in three independent replicates for each oxysterol (R1-R3).

2022-06-16 | MSV000089661 | MassIVE

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