The terminal enzymes of cholesterol synthesis, DHCR24 and DHCR7, interact physically and functionally

Luu, Winnie; Hart‐Smith, Gene; Sharpe, Laura J.; Brown, Andrew

doi:10.1194/jlr.m056986

Cited by 70 publications

(58 citation statements)

References 38 publications

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“…Previous studies examining cholesterol changes in HD mouse models have focused on several major sterols in whole brain homogenates at multiple time-points during disease progression, or in specific brain regions at a single time-point. Recent studies suggesting more complex cholesterol synthetic regulation in the later stages of the cholesterol synthetic pathway [15,16] highlights the relevance of this study investigating a wider variety of cholesterol synthetic precursors.…”

Section: Discussionmentioning

confidence: 82%

“…Measurement of individual precursors alone to interpret synthetic rate may be potentially confounding. The cellular regulation of cholesterol synthesis occurring downstream of squalene has been investigated recently and identified the two terminal enzymes in the pathway interact functionally, DHCR24 regulating the activity of 7-dehydrocholesterol reductase (DHCR7) [16]. DHCR24 is also believed to have further regulatory roles upstream in the pathway [16], however these roles have not been fully established and cholesterol synthetic regulation in the brain is still to be completely understood.…”

Section: Discussionmentioning

confidence: 99%

“…The mean body weight of R6/1 mice did not increase after 16 weeks of age in males, and 19 weeks in females. Prior to weight loss (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) weeks) the rate of weight gain was significantly less in female R6/1 mice compared to WT (p = 0.00012). No significant difference in the rate of weight gain was detected between male R6/1 and WT mice in the 6-16 week period.…”

Section: Weight Loss In R6/1 Mousementioning

confidence: 98%

“…Cholesterol biosynthetic regulation is thought to involve a complex interplay between sterol sensing elements [sterol regulatory element-binding proteins (SREBPs)] and transcription factors responsible for producing cholesterol synthetic enzymes [14]. However, recent evidence suggests that further regulation of cholesterol synthesis may occur in the later stages of the pathway [15,16]. The later stages of the cholesterol biosynthetic pathway are branched into the Kandutsch-Russell and Bloch pathways.…”

Section: Introductionmentioning

confidence: 99%

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Brain Cholesterol Synthesis and Metabolism is Progressively Disturbed in the R6/1 Mouse Model of Huntington’s Disease: A Targeted GC-MS/MS Sterol Analysis

Kreilaus

Spiro

Hannan

et al. 2015

JHD

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. (2015). Brain cholesterol synthesis and metabolism is progressively disturbed in the R6/1 mouse model of Huntington's disease: a targeted GC-MS/MS sterol analysis. Journal of Huntington's Disease, 4 (4), 305-318.Brain cholesterol synthesis and metabolism is progressively disturbed in the R6/1 mouse model of Huntington' s disease: a targeted GC-MS/MS sterol analysis AbstractBackground:Cholesterol has essential functions in neurological processes that require tight regulation of synthesis and metabolism. Perturbed cholesterol homeostasis has been demonstrated in Huntington's disease, however the exact role of these changes in disease pathogenesis is not fully understood. Objective:This study aimed to comprehensively examine changes in cholesterol biosynthetic precursors, metabolites and oxidation products in the striatum and cortex of the R6/1 transgenic mouse model of Huntington's disease. We also aimed to characterise the progression of the physical phenotype in these mice. Methods:GC-MS/MS was used to quantify a broad range of sterols in the striatum and cortex of R6/1 and wild type mice at 6, 12, 20, 24 and 28 weeks of age. Motor dysfunction was assessed over 28 weeks using the RotaRod and the hind-paw clasping tests. Results:24(S)-Hydroxycholesterol and 27-hydroxycholesterol were the major cholesterol metabolites that significantly changed in R6/1 mice. These changes were specifically localised to the striatum and were detected at the end stages of the disease. Cholesterol synthetic precursors (lathosterol and lanosterol) were significantly reduced in the cortex and striatum by 6 weeks of age, prior to the onset of motor dysfunction, as well as the cognitive and affective abnormalities previously reported. Elevated levels of desmosterol, a substrate of delta(24)-sterol reductase (DHCR24), were also detected in R6/1 mice at the end time-point. Female R6/1 mice exhibited a milder weight loss and hind paw clasping phenotype compared to male R6/1 mice, however, no difference in the brain sterol profile was detected between sexes. Conclusion:Several steps in cholesterol biosynthetic and metabolic pathways are differentially altered in the R6/1 mouse brain as the disease progresses and this is most severe in the striatum. This provides further insights into early molecular mediators of HD onset and disease progression and identifies candidate molecular targets for novel therapeutic approaches.

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Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Section: Weight Loss In R6/1 Mousementioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Brain Cholesterol Synthesis and Metabolism is Progressively Disturbed in the R6/1 Mouse Model of Huntington’s Disease: A Targeted GC-MS/MS Sterol Analysis

Kreilaus

Spiro

Hannan

et al. 2015

JHD

View full text Add to dashboard Cite

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“…Expression Plasmids-The protein-coding sequence of human DHCR7 (NM_001360.2) was cloned from cDNA into pGEM T-easy (Promega) and subcloned into pcDNA4 (Life Technologies) with a C-terminal V5-epitope tag and into pcDNA5-FRT (Life Technologies) with a C-terminal myc tag that was used previously (21). The plasmid pcDNA4-DHCR7-V5 was used as the template to generate amino acid mutations via site-directed mutagenesis, whereas pcDNA5-DHCR7-myc-FRT was used to create the stable cell lines for this study.…”

Section: Methodsmentioning

confidence: 99%

Cholesterol-mediated Degradation of 7-Dehydrocholesterol Reductase Switches the Balance from Cholesterol to Vitamin D Synthesis

Prabhu

Luu

Sharpe

et al. 2016

Journal of Biological Chemistry

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121

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Cholesterol is detrimental to human health in excess but is also essential for normal embryogenesis. Hence, enzymes involved in its synthesis possess many layers of regulation to achieve balanced cholesterol levels. 7-Dehydrocholesterol reductase (DHCR7) is the terminal enzyme of cholesterol synthesis in the Kandutsch-Russell pathway, converting 7-dehydrocholesterol (7DHC) to cholesterol. In the absence of functional DHCR7, accumulation of 7DHC and a lack of cholesterol production leads to the devastating developmental disorder, Smith-Lemli-Opitz syndrome. This study identifies that statin treatment can ameliorate the low DHCR7 expression seen with common Smith-Lemli-Opitz syndrome mutations. Furthermore, we show that wild-type DHCR7 is also relatively labile. In an example of end-product inhibition, cholesterol accelerates the proteasomal degradation of DHCR7, resulting in decreased protein levels and activity. The loss of enzymatic activity results in the accumulation of the substrate 7DHC, which leads to an increased production of vitamin D. Thus, these findings highlight DHCR7 as an important regulatory switch between cholesterol and vitamin D synthesis.

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Measuring Activity of Cholesterol Synthesis Enzymes Using Gas Chromatography/Mass Spectrometry

Prabhu

Luu

Brown

2017

Methods in Molecular Biology

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The development of gas chromatography/mass spectrometry (GC/MS) technology has improved the ease and efficiency with which sterols in biological samples can be analyzed. Its advantages include that it needs only a small amount of sample, a short analysis time, and has enhanced specificity over traditional methods. Furthermore, a major benefit is its nonselective properties, which means that a complete scan of the sample will display the relative abundance of every sterol in the sample. This property has made it possible to define the abnormal, but distinctive, sterol profiles in a number of inborn errors of cholesterol synthesis. Here, we describe a semiquantitative method to determine relative activity of cholesterol synthesis enzymes. As an example, we measure the relative abundance of the substrate and product sterols of a cholesterol synthetic enzyme, 24-dehydrocholesterol reductase (DHCR24), which is defective in the hereditary developmental disease desmosterolosis.

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The terminal enzymes of cholesterol synthesis, DHCR24 and DHCR7, interact physically and functionally

Cited by 70 publications

References 38 publications

Brain Cholesterol Synthesis and Metabolism is Progressively Disturbed in the R6/1 Mouse Model of Huntington’s Disease: A Targeted GC-MS/MS Sterol Analysis

Brain Cholesterol Synthesis and Metabolism is Progressively Disturbed in the R6/1 Mouse Model of Huntington’s Disease: A Targeted GC-MS/MS Sterol Analysis

Cholesterol-mediated Degradation of 7-Dehydrocholesterol Reductase Switches the Balance from Cholesterol to Vitamin D Synthesis

Measuring Activity of Cholesterol Synthesis Enzymes Using Gas Chromatography/Mass Spectrometry

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