Branch-point reactions in the biosynthesis of cholesterol, dolichol, ubiquinone and prenylated proteins

Understanding coenzyme Q

Coenzyme Q (CoQ), also known as ubiquinone, comprises a benzoquinone head group and a long isoprenoid side chain. It is thus extremely hydrophobic and resides in membranes. It is best known for its complex function as an electron transporter in the mitochondrial electron transport chain (ETC) but is also required for several other crucial cellular processes. In fact, CoQ appears to be central to the entire redox balance of the cell. Remarkably, its structure and therefore its properties have not changed from bacteria to vertebrates. In metazoans, it is synthesized in all cells and is found in most, and maybe all, biological membranes. CoQ is also known as a nutritional supplement, mostly because of its involvement with antioxidant defenses. However, whether there is any health benefit from oral consumption of CoQ is not well established. Here we review the function of CoQ as a redox-active molecule in the ETC and other enzymatic systems, its role as a prooxidant in reactive oxygen species generation, and its separate involvement in antioxidant mechanisms. We also review CoQ biosynthesis, which is particularly complex because of its extreme hydrophobicity, as well as the biological consequences of primary and secondary CoQ deficiency, including in human patients. Primary CoQ deficiency is a rare inborn condition due to mutation in CoQ biosynthetic genes. Secondary CoQ deficiency is much more common, as it accompanies a variety of pathological conditions, including mitochondrial disorders as well as aging. In this context, we discuss the importance, but also the great difficulty, of alleviating CoQ deficiency by CoQ supplementation.

Biological Demands and Toxicity of Isoprenoid Precursors in Bacillus Subtilis Through Cell-Permeant Analogs of Isopentenyl Pyrophosphate and Dimethylallyl Pyrophosphate

Bacterial isoprenoids are necessary for many biological processes, including maintaining membrane integrity, facilitating intercellular communication, and preventing oxidative damage. All bacterial isoprenoids are biosynthesized from two five carbon structural isomers, isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), which are cell impermeant. Herein, we demonstrate exogenous delivery of IPP and DMAPP into Bacillus subtilis by utilizing a self-immolative ester (SIE)-caging approach. We initially evaluated native B. subtilis esterase activity, which revealed a preference for short straight chain esters. We then examined the viability of the SIE-caging approach in B. subtilis and demonstrate that the released caging groups are well tolerated and the released IPP and DMAPP are bioavailable, such that isoprenoid biosynthesis can be rescued in the presence of pathway inhibitors. We further show that IPP and DMAPP are both toxic and inhibit growth of B. subtilis at the same concentration. Lastly, we establish the optimal ratio of IPP to DMAPP (5 : 1) for B. subtilis growth and find that, surprisingly, DMAPP alone is insufficient to rescue isoprenoid biosynthesis under high concentrations of fosmidomycin. These findings showcase the potential of the SIE-caging approach in B. subtilis and promise to both aid in novel isoprenoid discovery and to inform metabolic engineering efforts in bacteria.

Genetic insights into superior grain number traits: a QTL analysis of wheat-Agropyron cristatum derivative pubing3228

BACKGROUND

Agropyron cristatum (L.) is a valuable genetic resource for expanding the genetic diversity of common wheat. Pubing3228, a novel wheat-A. cristatum hybrid germplasm, exhibits several desirable agricultural traits, including high grain number per spike (GNS). Understanding the genetic architecture of GNS in Pubing3228 is crucial for enhancing wheat yield. This study aims to analyze the specific genetic regions and alleles associated with high GNS in Pubing3228.

METHODS

The study employed a recombination inbred line (RIL) population derived from a cross between Pubing3228 and Jing4839 to investigate the genetic regions and alleles linked to high GNS. Quantitative Trait Loci (QTL) analysis and candidate gene investigation were utilized to explore these traits.

RESULTS

A total of 40 QTLs associated with GNS were identified across 16 chromosomes, accounting for 4.25-17.17% of the total phenotypic variation. Five QTLs (QGns.wa-1D, QGns.wa-5 A, QGns.wa-7Da.1, QGns.wa-7Da.2 and QGns.wa-7Da.3) accounter for over 10% of the phenotypic variation in at least two environments. Furthermore, 94.67% of the GNS QTL with positive effects originated from Pubing3228. Candidate gene analysis of stable QTLs identified 11 candidate genes for GNS, including a senescence-associated protein gene (TraesCS7D01G148000) linked to the most significant SNP (AX-108,748,734) on chromosome 7D, potentially involved in reallocating nutrients from senescing tissues to developing seeds.

CONCLUSION

This study provides new insights into the genetic mechanisms underlying high GNS in Pubing3228, offering valuable resources for marker-assisted selection in wheat breeding to enhance yield.

Physiological adventures in Candida albicans: farnesol and ubiquinones

SUMMARYFarnesol was first identified as a quorum-sensing molecule, which blocked the yeast to hyphal transition in Candida albicans, 22 years ago. However, its interactions with Candida biology are surprisingly complex. Exogenous (secreted or supplied) farnesol can also act as a virulence factor during pathogenesis and as a fungicidal agent triggering apoptosis in other competing fungi. Farnesol synthesis is turned off both during anaerobic growth and in opaque cells. Distinctly different cellular responses are observed as exogenous farnesol levels are increased from 0.1 to 100 µM. Reported changes include altered morphology, stress response, pathogenicity, antibiotic sensitivity/resistance, and even cell lysis. Throughout, there has been a dearth of mechanisms associated with these observations, in part due to the absence of accurate measurement of intracellular farnesol levels (Fi). This obstacle has recently been overcome, and the above phenomena can now be viewed in terms of changing Fi levels and the percentage of farnesol secreted. Critically, two aspects of isoprenoid metabolism present in higher organisms are absent in C. albicans and likely in other yeasts. These are pathways for farnesol salvage (converting farnesol to farnesyl pyrophosphate) and farnesylcysteine cleavage, a necessary step in the turnover of farnesylated proteins. Together, these developments suggest a unifying model, whereby high, threshold levels of Fi regulate which target proteins are farnesylated or the extent to which they are farnesylated. Thus, we suggest that the diversity of cellular responses to farnesol reflects the diversity of the proteins that are or are not farnesylated.

Hem25p is required for mitochondrial IPP transport in fungi

Coenzyme Q (CoQ, ubiquinone) is an essential cellular cofactor composed of a redox-active quinone head group and a long hydrophobic polyisoprene tail. How mitochondria access cytosolic isoprenoids for CoQ biosynthesis is a longstanding mystery. Here, via a combination of genetic screening, metabolic tracing and targeted uptake assays, we reveal that Hem25p-a mitochondrial glycine transporter required for haem biosynthesis-doubles as an isopentenyl pyrophosphate (IPP) transporter in Saccharomyces cerevisiae. Mitochondria lacking Hem25p failed to efficiently incorporate IPP into early CoQ precursors, leading to loss of CoQ and turnover of CoQ biosynthetic proteins. Expression of Hem25p in Escherichia coli enabled robust IPP uptake and incorporation into the CoQ biosynthetic pathway. HEM25 orthologues from diverse fungi, but not from metazoans, were able to rescue hem25∆ CoQ deficiency. Collectively, our work reveals that Hem25p drives the bulk of mitochondrial isoprenoid transport for CoQ biosynthesis in fungi.

Geranylgeranoic acid, a bioactive and endogenous fatty acid in mammals: a review

Geranylgeranoic acid (GGA) was first reported in 1983 as one of the mevalonic acid (MVA) metabolites, but its biological significance was not studied for a long time. Our research on the antitumor effects of retinoids led us to GGA, one of the acyclic retinoids that induce cell death in human hepatoma-derived cell lines. We were able to demonstrate the presence of endogenous GGA in various tissues of male rats, including the liver, testis, and cerebrum, by LC-MS/MS. Furthermore, the biosynthesis of GGA from MVA in mammals including humans was confirmed by isotopomer spectral analysis using ¹³C-labeled mevalonolactone and cultured hepatoma cells, and the involvement of hepatic monoamine oxidase B (MAOB) in the biosynthesis of GGA was also demonstrated. The biological activity of GGA was analyzed from the retinoid (differentiation induction) and non-retinoid (cell death induction) aspects, and in particular, the non-retinoid mechanism by which GGA induces cell death in hepatoma cells was found to involve pyroptosis via ER-stress responses initiated by TLR4 signaling. In addition to these effects of GGA, we also describe the in vivo effects of GGA on reproduction. In this review, based mainly on our published papers, we have shown that hepatic MAOB is involved in the biosynthesis of GGA and that GGA induces cell death in human hepatoma-derived cell lines by non-canonical pyroptosis, one of the mechanisms of sterile inflammatory cell death.

Insights into the malfunctioning of the mitochondrial citrate carrier: Implications for cell pathology

The mitochondrial citrate carrier (CIC) is a member of the mitochondrial carrier family and is responsible for the transit of tricarboxylates and dicarboxylates across the inner membrane. By modulating the flux of these molecules, it represents the molecular link between catabolic and anabolic reactions that take place in distinct cellular sub-compartments. Therefore, this transport protein represents an important element of investigation both in physiology and in pathology. In this review we critically analyze the involvement of the mitochondrial CIC in several human pathologies, which can be divided into two subgroups, one characterized by a decrease and the other by an increase in the flux of citrate across the inner mitochondrial membrane. In particular, a decrease in the activity of the mitochondrial CIC is responsible for several congenital diseases of different severity, which are also characterized by the increase in urinary levels of L-2- and D-2-hydroxyglutaric acids. On the other hand, an increase in the activity of the mitochondrial CIC is involved, in various ways, in the onset of inflammation, autoimmune diseases, and cancer. Then, understanding the role of CIC and the mechanisms driving the flux of metabolic intermediates between mitochondria and cytosol would potentially allow for manipulation and control of metabolism in pathological conditions.

Squalene hopene cyclases and oxido squalene cyclases: potential targets for regulating cyclisation reactions

Squalene hopene cyclases (SHC) convert squalene, the linear triterpene to fused ring product hopanoid by the cationic cyclization mechanism. The main function of hopanoids, a class of pentacyclic triterpenoids in bacteria involves the maintenance of membrane fluidity and stability. 2, 3-oxido squalene cyclases are functional analogues of SHC in eukaryotes and both these enzymes have fascinated researchers for the high stereo selectivity, complexity, and efficiency they possess. The peculiar property of the enzyme squalene hopene cyclase to accommodate substrates other than its natural substrate can be exploited for the use of these enzymes in an industrial perspective. Here, we present an extensive overview of the enzyme squalene hopene cyclase with emphasis on the cloning and overexpression strategies. An attempt has been made to explore recent research trends around squalene cyclase mediated cyclization reactions of flavour and pharmaceutical significance by using non-natural molecules as substrates.

Hem25p is a mitochondrial IPP transporter

Coenzyme Q (CoQ, ubiquinone) is an essential cellular cofactor comprised of a redox-active quinone head group and a long hydrophobic polyisoprene tail. How mitochondria access cytosolic isoprenoids for CoQ biosynthesis is a longstanding mystery. Here, via a combination of genetic screening, metabolic tracing, and targeted uptake assays, we reveal that Hem25p-a mitochondrial glycine transporter required for heme biosynthesis-doubles as an isopentenyl pyrophosphate (IPP) transporter in Saccharomyces cerevisiae. Mitochondria lacking Hem25p fail to efficiently incorporate IPP into early CoQ precursors, leading to loss of CoQ and turnover of CoQ biosynthetic proteins. Expression of Hem25p in Escherichia coli enables robust IPP uptake demonstrating that Hem25p is sufficient for IPP transport. Collectively, our work reveals that Hem25p drives the bulk of mitochondrial isoprenoid transport for CoQ biosynthesis in yeast.

Genome-Wide Identification and Expression Analysis of UBiA Family Genes Associated with Abiotic Stress in Sunflowers (Helianthus annuus L.)

The UBiA genes encode a large class of isopentenyltransferases, which are involved in the synthesis of secondary metabolites such as chlorophyll and vitamin E. They performed important functions in the whole plant's growth and development. Current studies on UBiA genes were not comprehensive enough, especially for sunflower UBiA genes. In this study, 10 HaUBiAs were identified by domain analysis these HaUBiAs had five major conserved domains and were unevenly distributed on six chromosomes. By constructing phylogenetic trees, 119 UBiA genes were found in 12 species with different evolutionary levels and divided into five major groups, which contained seven conserved motifs and eight UBiA subsuper family domains. Tissue expression analysis showed that HaUBiAs were highly expressed in the roots, leaves, and seeds. By using promoter analysis, the cis-elements of UBiA genes were mainly in hormone signaling and stress responses. The qRT-PCR results showed that HaUBiA1 and HaUBiA5 responded strongly to abiotic stresses. Under ABA and MeJA treatments, HaUBiA1 significantly upregulated, while HaUBiA5 significantly decreased. Under cold stress, the expression of UBiA1 was significantly upregulated in the roots and stems, while UBiA5 expression was increased only in the leaves. Under anaerobic induction, UBiA1 and UBiA5 were both upregulated in the roots, stems and leaves. In summary, this study systematically classified the UBiA family and identified two abiotic stress candidate genes in the sunflower. It expands the understanding of the UBiA family and provides a theoretical basis for future abiotic stress studies in sunflowers.

Membrane Permeant Analogs for Independent Cellular Introduction of the Terpene Precursors Isopentenyl- and Dimethylallyl-Pyrophosphate

Isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) are the central five-carbon precursors to all terpenes. Despite their significance, exogenous, independent delivery of IPP and DMAPP to cells is impossible as the negatively charged pyrophosphate makes these molecules membrane impermeant. Herein, we demonstrate a facile method to circumvent this challenge through esterification of the β-phosphate with two self-immolative esters (SIEs) that neutralize the negatively charged pyrophosphate to yield membrane-permeant analogs of IPP and DMAPP. Following cellular incorporation, general esterase activity initiates cleavage of the SIEs, resulting in traceless release of IPP and DMAPP for metabolic utilization. Addition of the synthesized IPP and DMAPP precursor analogs rescued cell growth of glioblastoma (U-87MG) cancer cells concurrently treated with the HMG-CoA reductase inhibitor pitavastatin, which otherwise abrogates cell growth via blocking production of IPP and DMAPP. This work demonstrates a new application of a prodrug strategy to incorporate a metabolic intermediate and promises to enable future interrogation of the distinct biological roles of IPP and DMAPP.

Molecular Cloning and Functional Analysis of DXS and FPS Genes from Zanthoxylum bungeanum Maxim

Zanthoxylum bungeanum Maxim. (Z. bungeanum) has attracted attention for its rich aroma. The aroma of Z. bungeanum is mainly volatile terpenes synthesized by plant terpene metabolic pathways. However, there is little information on Z. bungeanum terpene metabolic gene. In this study, the coding sequence of 1-deoxy-D-xylulose-5-phosphate synthase (DXS) and farnesyl pyrophosphate synthase (FPS) were cloned from Z. bungeanum cv. 'Fengxiandahongpao.' ZbDXS and ZbFPS genes from Z. bungeanum with CDS lengths of 2172 bp and 1029 bp, respectively. The bioinformatics results showed that Z. bungeanum was closely related to citrus, and it was deduced that ZbFPS were hydrophilic proteins without the transmembrane domain. Subcellular localization prediction indicated that ZbDXS was most likely to be located in chloroplasts, and ZbFPS was most likely to be in mitochondria. Meanwhile, the 3D protein structure showed that ZbDXS and ZbFPS were mainly composed of α-helices, which were folded into a single domain. In vitro enzyme activity experiments showed that purified proteins ZbDXS and ZbFPS had the functions of DXS enzyme and FPS enzyme. Transient expression of ZbDXS and ZbFPS in tobacco significantly increased tobacco's terpene content. Moreover, ZbDXS and ZbFPS were expressed in different tissues of Z. bungeanum, and the relative expression of the two genes was the highest in fruits. Therefore, this suggests that ZbDXS and ZbFPS are positively related to terpene synthesis. This study could provide reference genes for improving Z. bungeanum breeding as well as for the Rutaceae research.

Liver proteome profiling in dairy cows during the transition from gestation to lactation: Effects of supplementation with essential fatty acids and conjugated linoleic acids as explored by PLS-DA

This study aimed at investigating the synergistic effects of essential fatty acids (EFA) and conjugated linoleic acids (CLA) on the liver proteome profile of dairy cows during the transition to lactation. 16 Holstein cows were infused from 9 wk. antepartum to 9 wk. postpartum into the abomasum with either coconut oil (CTRL) or a mixture of EFA (linseed + safflower oil) and CLA (EFA + CLA). Label-free quantitative proteomics was performed in liver tissue biopsied at days -21, +1, +28, and + 63 relative to calving. Differentially abundant proteins (DAP) between treatment groups were identified at the intersection between a multivariate and a univariate analysis. In total, 1680 proteins were identified at each time point, of which between groups DAP were assigned to the metabolism of xenobiotics by cytochrome P450, drug metabolism - cytochrome P450, steroid hormone biosynthesis, glycolysis/gluconeogenesis, and glutathione metabolism. Cytochrome P450, as a central hub, enriched with specific CYP enzymes comprising: CYP51A1 (d - 21), CYP1A1 & CYP4F2 (d + 28), and CYP4V2 (d + 63). Collectively, supplementation of EFA + CLA in transition cows impacted hepatic lipid metabolism and enriched several common biological pathways at all time points that were mainly related to ω-oxidation of fatty acids through the Cytochrome p450 pathway. SIGNIFICANCE: In three aspects this manuscript is notable. First, this is among the first longitudinal proteomics studies in nutrition of dairy cows. The selected time points are critical periods around parturition with profound endocrine and metabolic adaptations. Second, our findings provided novel information on key drivers of biologically relevant pathways suggested according to previously reported performance, zootechnical, and metabolism data (already published elsewhere). Third, our results revealed the role of cytochrome P450 that is hardly investigated, and of ω-oxidation pathways in the metabolism of fatty acids with the involvement of specific enzymes.

Glucose starvation suppresses gastric cancer through targeting miR-216a-5p/Farnesyl-Diphosphate Farnesyltransferase 1 axis

Background

Fasting mimic diet is an effect approach for gastric cancer (GC) treatment. Exploring mechanisms of glucose deprivation-mediated GC suppression is required to develop novel therapeutic regimens. Farnesyltransferase 1 (FDFT1), as a novel target in basic research, has been reported to regulate malignant progression in some types of cancer. However, biological functions of FDFT1 in GC are still unclear. This study focused on biological functions of FDFT1 in GC and the association between glucose starvation (GS) and FDFT1.

Methods

The data derived from the Kaplan–Meier Plotter database were collected to identify the relationship between survival time and FDFT1 expression levels of GC patients. Bioinformatic analysis was performed to explore the biological functions of FDFT1. The expression levels of targeted genes and microRNAs (miRNAs) were detected with immunohistochemistry, quantitative real-time PCR and western blot. Malignant behaviors were measured using cell counting, cell counting kit-8, 5-ethynyl-2-deoxyuridine, wound healing, invasion transwell assays in vitro and constructions of subcutaneous and lung-metastatic tumors in vivo. The glycolysis of GC cells was determined by a series of metabolites, including lactate acid, pyruvic acid, ATP production, rates of glucose uptake, extracellular acidification rate and oxygen consumption rate.

Results

FDFT1 was downregulated in GC and negatively correlated with pathological T stage, pathological TNM stage and cancer differentiation. High expression of FDFT1 also indicated better prognosis of GC patients. FDFT1 upregulation attenuated proliferation, migration and invasion of GC. miR-216a-5p was identified as a critical suppressor of FDFT1 expression and miR-216a-5p/FDFT1 axis regulated malignant behaviors and glycolysis of GC cells. GS suppressed malignant behaviors of GC by targeting miR-216a-5p/FDFT1 axis both in vitro and in vivo.

Conclusion

This study illustrated novel mechanisms by which GS effectively suppresses GC. FDFT1 may become a potential prognostic indicator and novel target of GC therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02416-7.

Genetic evidence for the requirements of antroquinonol biosynthesis by Antrodia camphorata during liquid-state fermentation

The solid-state fermentation of Antrodia camphorata could produce a variety of ubiquinone compounds, such as antroquinonol (AQ). However, AQ is hardly synthesized during liquid-state fermentation (LSF). To investigates the mechanism of AQ synthesis, three precursors (ubiquinone 0 UQ0, farnesol and farnesyl diphosphate FPP) were added in LSF. The results showed that UQ0 successfully induced AQ production; however, farnesol and FPP could not induce AQ synthesis. The precursor that restricts the synthesis of AQ is the quinone ring, not the isoprene side chain. Then, the Agrobacterium-mediated transformation system of A. camphorata was established and the genes for quinone ring modification (coq2-6) and isoprene synthesis (HMGR, fps) were overexpressed. The results showed that overexpression of genes for isoprene side chain synthesis could not increase the yield of AQ, but overexpression of coq2 and coq5 could significantly increase AQ production. This is consistent with the results of the experiment of precursors. It indicated that the A. camphorata lack the ability to modify the quinone ring of AQ during LSF. Of the modification steps, prenylation of UQ0 is the key step of AQ biosynthesis. The result will help us to understand the genetic evidence for the requirements of AQ biosynthesis in A. camphorata.

PCSK9 Induces Rat Smooth Muscle Cell Proliferation and Counteracts the Pleiotropic Effects of Simvastatin

Human atherosclerotic plaque contains smooth muscle cells (SMCs) negative for the contractile phenotype (α-smooth muscle actin) but positive for proprotein convertase subtilisin/kexin type 9 (PCSK9). Thus, we generated rat SMCs which overexpressed human PCSK9 (SMCs^PCSK9) with the aim of investigating the role of PCSK9 in the phenotype of SMCs. PCSK9 overexpression in SMCs^PCSK9 led to a significant downregulation of the low-density lipoprotein receptor (Ldlr) as well as transgelin (Sm22α), a marker of the contractile phenotype. The cell proliferation rate of SMCs^PCSK9 was significantly faster than that of the control SMCs (SMCs^puro). Interestingly, overexpression of PCSK9 did not impact the migratory capacity of SMCs in response to 10% FCS, as determined by Boyden's chamber assay. Expression and activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (Hmgcr) was significantly increased in the presence of PCSK9, both in SMC^PCSK9 and after treatment with recombinant PCSK9. The transcriptional activity of sterol regulatory element-binding protein (SREBP) was also increased in the presence of PSCK9, suggesting a direct role of PCSK9 in the control of SRE-responsive genes, like HMGCR. We also observed that cholesterol biosynthesis is elevated in SMC^PCSK9, potentially explaining the increased proliferation observed in these cells. Finally, concentration-dependent experiments with simvastatin demonstrated that SMCs^PCSK9 were partially resistant to the antiproliferative and antimigratory effect of this drug. Taken together, these data further support a direct role of PCSK9 in proliferation, migration, and phenotypic changes in SMCs-pivotal features of atherosclerotic plaque development. We also provide new evidence on the role of PCSK9 in the pharmacological response to statins-gold standard lipid-lowering drugs with pleiotropic action.

Roles of Farnesyl-Diphosphate Farnesyltransferase 1 in Tumour and Tumour Microenvironments

Farnesyl-diphosphate farnesyltransferase 1 (FDFT1, squalene synthase), a membrane-associated enzyme, synthesizes squalene via condensation of two molecules of farnesyl pyrophosphate. Accumulating evidence has noted that FDFT1 plays a critical role in cancer, particularly in metabolic reprogramming, cell proliferation, and invasion. Based on these advances in our knowledge, FDFT1 could be a potential target for cancer treatment. This review focuses on the contribution of FDFT1 to the hallmarks of cancer, and further, we discuss the applicability of FDFT1 as a cancer prognostic marker and target for anticancer therapy.

Functional replacement of isoprenoid pathways in Rhodobacter sphaeroides

Advances in synthetic biology and metabolic engineering have proven the potential of introducing metabolic by-passes within cell factories. These pathways can provide a more efficient alternative to endogenous counterparts due to their insensitivity to host's regulatory mechanisms. In this work, we replaced the endogenous essential 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway for isoprenoid biosynthesis in the industrially relevant bacterium Rhodobacter sphaeroides by an orthogonal metabolic route. The native 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway was successfully replaced by a heterologous mevalonate (MVA) pathway from a related bacterium. The functional replacement was confirmed by analysis of the reporter molecule amorpha-4,11-diene after cultivation with [4-13 C]glucose. The engineered R. sphaeroides strain relying exclusively on the MVA pathway was completely functional in conditions for sesquiterpene production and, upon increased expression of the MVA enzymes, it reached even higher sesquiterpene yields than the control strain coexpressing both MEP and MVA modules. This work represents an example where substitution of an essential biochemical pathway by an alternative, heterologous pathway leads to enhanced biosynthetic performance.

Zingerone in the Flower of Passiflora Maliformis Attracts an Australian Fruit Fly, Bactrocera Jarvisi (Tryon)

Passiflora maliformis is an introduced plant in Australia but its flowers are known to attract the native Jarvis’s fruit fly, Bactrocera jarvisi (Tryon). The present study identifies and quantifies likely attractant(s) of male B. jarvisi in P. maliformis flowers. The chemical compositions of the inner and outer coronal filaments, anther, stigma, ovary, sepal, and petal of P. maliformis were separately extracted with ethanol and analyzed using gas chromatography-mass spectrometry (GC-MS). Polyisoprenoid lipid precursors, fatty acids and their derivatives, and phenylpropanoids were detected in P. maliformis flowers. Phenylpropanoids included raspberry ketone, cuelure, zingerone, and zingerol, although compositions varied markedly amongst the flower parts. P. maliformis flowers were open for less than one day, and the amounts of some of the compounds decreased throughout the day. The attraction of male B. jarvisi to P. maliformis flowers is most readily explained by the presence of zingerone in these flowers.

Cholesterol-Lowering Action of a Novel Nutraceutical Combination in Uremic Rats: Insights into the Molecular Mechanism in a Hepatoma Cell Line

Appropriate nutraceutical combinations may represent a valid approach to prevent vascular calcification associated with chronic kidney disease (CKD). In the present study, we tested the effect of a new nutraceutical combination named RenaTris^®, containing MK-7, magnesium carbonate, and Sucrosomial^® Iron, on vascular calcification in uremic rats. Rats were randomly divided into three groups, i.e. control (high-phosphate diet), uremic (high-phosphate diet containing 0.5% adenine), and supplemented uremic diet (0.5% adenine, MK-7, magnesium carbonate, and Sucrosomial^® Iron). After six weeks, sera and vascular calcification were examined. The uremic diet increased creatinine and phosphate levels and induced extensive vascular calcification. The uremic condition also induced a mild hypercholesterolemic condition (+52% of total cholesterol; p < 0.05). The supplemented uremic diet did not reduce creatinine, phosphate levels, or vascular calcification, however, we observed a significant hypocholesterolemic effect (-18.9% in supplemental uremic vs. uremic diet; p < 0.05). Similar to simvastatin, incubation of cultured human hepatoma cells (Huh7) with MK-7 significantly reduced cholesterol biosynthesis (-38%) and induced 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase and low-density lipoprotein receptor (LDLR) at both mRNA and protein levels. The effect of MK-7 on LDLR was counteracted by the co-incubation with squalene. Unlike simvastatin, MK-7 reduced PCSK9 in Huh7. These results indicated that the new nutraceutical combination significantly impacts cholesterol metabolism and its supplementation may help to control mild hypercholesterolemic conditions in CKD patients.

SmPPT, a 4-hydroxybenzoate polyprenyl diphosphate transferase gene involved in ubiquinone biosynthesis, confers salt tolerance in Salvia miltiorrhiza

SmPPT, which encodes 4-hydroxybenzoate polyprenyl diphosphate transferase involved in ubiquinone biosynthesis, confers salt tolerance to S. miltiorrhiza through enhancing the activities of POD and CAT to scavenge ROS. Ubiquinone (UQ), also known as coenzyme Q (CoQ), is a key electron transporter in the mitochondrial respiratory system. UQ is composed of a benzene quinone ring and a polyisoprenoid side chain. Attachment of polyisoprenoid side chain to the benzene quinone ring is a rate-limiting step catalyzed by 4-hydroxybenzoate polyprenyl diphosphate transferase (PPT). So far, only a few plant PPT-encoding genes have been functionally analyzed. Through genome-wide analysis and subsequent molecular cloning, a PPT-encoding gene, termed SmPPT, was identified from an economically and academically important medicinal model plant, Salvia miltiorrhiza. SmPPT contained many putative cis-elements associated with abiotic stresses in the promoter region and were responsive to PEG-6000 and methyl jasmonate treatments. The deduced SmPPT protein contains the PT_UbiA conserved domain of polyprenyl diphosphate transferase and an N-terminal mitochondria transit peptide. Transient expression assay of SmPPT-GFP fusion protein showed that SmPPT was mainly localized in the mitochondria. SmPPT could functionally complement coq2 mutation and catalyzed UQ6 production in yeast cells. Overexpression of SmPPT increased UQ production and enhanced salt tolerance in S. miltiorrhiza. Under salinity stress conditions, transgenic plants accumulated less H₂O₂ and malondialdehyde and exhibited higher peroxidase (POD) and catalase (CAT) activities compared with wild-type plants. It indicates that SmPPT confers salt tolerance to S. miltiorrhiza at least partially through enhancing the activities of POD and CAT to scavenge ROS.

Volatile organic compound (VOC) emissions of CHO and T cells correlate to their expansion in bioreactors

Volatile organic compound (VOC) emissions were measured from Chinese Hamster Ovary (CHO) cell and T cell bioreactor gas exhaust lines with the goal of non-invasively metabolically profiling the expansion process. Measurements of cellular 'breath' were made directly from the gas exhaust lines using polydimethylsiloxane (PDMS)-coated magnetic stir bars, which underwent subsequent thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) analysis. Baseline VOC profiles were observed from bioreactors filled with only liquid media. After inoculation, unique VOC profiles correlated to cell expansion over the course of 8 d. Partial least squares (PLS) regression models were built to predict cell culture density based on VOC profiles of CHO and T cells (R ² = 0.671 and R ² = 0.769, respectively, based on a validation data set). T cell runs resulted in 47 compounds relevant to expansion while CHO cell runs resulted in 45 compounds; the 20 most relevant compounds of each cell type were putatively identified. On the final experimental days, sorbent-covered stir bars were placed directly into cell-inoculated media and into media controls. Liquid-based measurements from spent media containing cells could be distinguished from media-only controls, indicating soluble VOCs excreted by the cells during expansion. A PLS-discriminate analysis (PLS-DA) was performed, and 96 compounds differed between T cell-inoculated media and media controls with 72 compounds for CHO cells; the 20 most relevant compounds of each cell line were putatively identified. This work demonstrates that the volatilome of cell cultures can be exploited by chemical detectors in bioreactor gas and liquid waste lines to non-invasively monitor cellular health and could possibly be used to optimize cell expansion conditions 'on-the-fly' with appropriate control loop systems. Although the basis for statistical models included compounds without certain identification, this work provides a foundation for future research of bioreactor emissions. Future studies must move towards identifying relevant compounds for understanding of underlying biochemistry.

Unequivocal evidence for endogenous geranylgeranoic acid biosynthesized from mevalonate in mammalian cells

Geranylgeranoic acid (GGA) has been reported to induce autophagic cell death via upregulation of lipid-induced unfolded protein response in several human hepatoma-derived cell lines, and its 4,5-didehydro derivative has been developed as a preventive agent against second primary hepatoma in clinical trials. We have previously reported that GGA is a natural diterpenoid synthesized in several medicinal herbs. Here, we provide unequivocal evidence for de novo GGA biosynthesis in mammals. First, with normal male Wistar rats, the levels of GGA in liver were found to be far greater than those in other organs analyzed. Second, we demonstrated the metabolic GGA labeling from the ¹³C-labeled mevalonolactone in the human hepatoma-derived cell line, HuH-7. Isotopomer spectral analysis revealed that approximately 80% of the cellular GGA was newly synthesized from mevalonate (MVA) in 12 h and the acid picked up preexisting farnesyl diphosphate (FPP) and geranylgeranyl diphosphate (GGPP), suggesting that GGA is derived from FPP and GGPP through the MVA pathway. Third, zaragozic acid A, a squalene synthase inhibitor, induced dose-dependent upregulation of endogenous GGA content in HuH-7 cells and their concomitant cell death. These results strongly suggest that a cancer-preventive GGA is biosynthesized via the MVA pathway in mammals.

Important drug-micronutrient interactions: A selection for clinical practice

Interactions between drugs and micronutrients have received only little or no attention in the medical and pharmaceutical world in the past. Since more and more pharmaceutics are used for the treatment of patients, this topic is increasingly relevant. As such interactions - depending on the duration of treatment and the status of micronutrients - impact the health of the patient and the action of the drugs, physicians and pharmacists should pay more attention to such interactions in the future. This review aims to sensitize physicians and pharmacists on drug micronutrient interactions with selected examples of widely pescribed drugs that can precipitate micronutrient deficiencies. In this context, the pharmacist, as a drug expert, assumes a particular role. Like no other professional in the health care sector, he is particularly predestined and called up to respond to this task. The following article intends to point out the relevance of mutual interactions between micronutrients and various examples of widely used drugs, without claiming to be exhaustive.

De Novo-Designed α-Helical Barrels as Receptors for Small Molecules

We describe de novo-designed α-helical barrels (αHBs) that bind and discriminate between lipophilic biologically active molecules. αHBs have five or more α-helices arranged around central hydrophobic channels the diameters of which scale with oligomer state. We show that pentameric, hexameric, and heptameric αHBs bind the environmentally sensitive dye 1,6-diphenylhexatriene (DPH) in the micromolar range and fluoresce. Displacement of the dye is used to report the binding of nonfluorescent molecules: palmitic acid and retinol bind to all three αHBs with submicromolar inhibitor constants; farnesol binds the hexamer and heptamer; but β-carotene binds only the heptamer. A co-crystal structure of the hexamer with farnesol reveals oriented binding in the center of the hydrophobic channel. Charged side chains engineered into the lumen of the heptamer facilitate binding of polar ligands: a glutamate variant binds a cationic variant of DPH, and introducing lysine allows binding of the biosynthetically important farnesol diphosphate.

Pathogenic mutations of the human mitochondrial citrate carrier SLC25A1 lead to impaired citrate export required for lipid, dolichol, ubiquinone and sterol synthesis

Missense mutations of the human mitochondrial citrate carrier, encoded by the SLC25A1 gene, lead to an autosomal recessive neurometabolic disorder characterised by neonatal-onset encephalopathy with severe muscular weakness, intractable seizures, respiratory distress, and lack of psychomotor development, often resulting in early death. Here, we have measured the effect of all twelve known pathogenic mutations on the transport activity. The results show that nine mutations abolish transport of citrate completely, whereas the other three reduce the transport rate by >70%, indicating that impaired citrate transport is the most likely primary cause of the disease. Some mutations may be detrimental to the structure of the carrier, whereas others may impair key functional elements, such as the substrate binding site and the salt bridge network on the matrix side of the carrier. To understand the consequences of impaired citrate transport on metabolism, the substrate specificity was also determined, showing that the human citrate carrier predominantly transports citrate, isocitrate, cis-aconitate, phosphoenolpyruvate and malate. Although D-2- and L-2 hydroxyglutaric aciduria is a metabolic hallmark of the disease, it is unlikely that the citrate carrier plays a significant role in the removal of hydroxyglutarate from the cytosol for oxidation to oxoglutarate in the mitochondrial matrix. In contrast, computer simulations of central metabolism predict that the export of citrate from the mitochondrion cannot be fully compensated by other pathways, restricting the cytosolic production of acetyl-CoA that is required for the synthesis of lipids, sterols, dolichols and ubiquinone, which in turn explains the severe disease phenotypes.

Geranylgeraniol prevents the simvastatin-induced PCSK9 expression: Role of the small G protein Rac1

Statins are known to increase the plasma levels of proprotein convertase subtilisin kexin type 9 (PCSK9) through the activation of the sterol responsive element binding protein (SREBP) pathway due to the inhibition of cholesterol biosynthesis. In the present study, we explore a possible role of the prenylated proteins on the statin-mediated PCSK9 induction in Caco-2 cells. Simvastatin (40μM) induced both PCSK9 mRNA (10.7±3.2 fold) and protein (2.2±0.3 fold), after 24h incubation. The induction of PCSK9 mRNA was partially, but significantly, prevented by the co-incubation with mevalonate (MVA), farnesol (FOH) and geranylgeraniol (GGOH), while a complete prevention was observed on secreted PCSK9, evaluated by ELISA assay. Under the same experimental conditions, MVA, GGOH, but not FOH, prevented the activation of the PCSK9 promoter by simvastatin in a SRE-dependent manner. Simvastatin reduced by -35.7±15.2% the Rac1-GTP levels, while no changes were observed on RhoA- and Cdc42-GTP. This effect was prevented by MVA and GGOH. A Rac inhibitor, and N17Rac1 dominant negative mutant, significantly induced PCSK9 levels, and a suppression of Rac1 expression by siRNA, counteract the effect of simvastatin on the induction of PCSK9 mRNA. Finally, simvastatin, and Rac inhibitor inhibited the nuclear translocation of STAT3 and its knock-down by siRNA increased significantly the susceptibility of Caco-2 to simvastatin on PCSK9 expression. Taken together, the present study reveal a direct role of Rac1 on simvastatin-mediated PCSK9 expression via the reduction of STAT3 nuclear translocation.

A Convenient Method for the Synthesis of (S)-Dolichol and (S)-Nordolichol

A procedure for the preparation of (S)-dolichol and (S)-nor-dolichol starting from the polyprenyl fraction extracted from Gingko Biloba integer or extracted leaves is described. Two chiral isoprenoid compounds in good yields and high degree of enantiomeric excess were obtained. The (S)-nordolichol appears to be a good chiral precursor for the preparation of 14C-labeled (S)-dolichol which is to be used in investigations aimed at gaining further information with respect to the role of dolichol in the function of living cells.

Coenzyme Q and Its Role in the Dietary Therapy against Aging

Coenzyme Q (CoQ) is a naturally occurring molecule located in the hydrophobic domain of the phospholipid bilayer of all biological membranes. Shortly after being discovered, it was recognized as an essential electron transport chain component in mitochondria where it is particularly abundant. Since then, more additional roles in cell physiology have been reported, including antioxidant, signaling, death prevention, and others. It is known that all cells are able to synthesize functionally sufficient amounts of CoQ under normal physiological conditions. However, CoQ is a molecule found in different dietary sources, which can be taken up and incorporated into biological membranes. It is known that mitochondria have a close relationship with the aging process. Additionally, delaying the aging process through diet has aroused the interest of scientists for many years. These observations have stimulated investigation of the anti-aging potential of CoQ and its possible use in dietary therapies to alleviate the effects of aging. In this context, the present review focus on the current knowledge and evidence the roles of CoQ cells, its relationship with aging, and possible implications of dietary CoQ in relation to aging, lifespan or age-related diseases.

Transcriptional Regulation of Cytosolic Sulfotransferase 1C2 by Intermediates of the Cholesterol Biosynthetic Pathway in Primary Cultured Rat Hepatocytes

Cytosolic sulfotransferase 1C2 (SULT1C2) is expressed in the kidney, stomach, and liver of rats; however, the mechanisms regulating expression of this enzyme are not known. We evaluated transcriptional regulation of SULT1C2 by mevalonate (MVA)-derived intermediates in primary cultured rat hepatocytes using several cholesterol synthesis inhibitors. Blocking production of mevalonate with the 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor pravastatin (30 μM), reduced SULT1C2 mRNA content by ∼40% whereas the squalene synthase inhibitor squalestatin (SQ1, 0.1 μM), which causes accumulation of nonsterol isoprenoids, increased mRNA content by 4-fold. Treatment with MVA (10 mM) strongly induced SULT1C2 mRNA by 12-fold, and this effect was blocked by inhibiting squalene epoxidase but not by more distal cholesterol inhibitors, indicating the effects of MVA are mediated by postsqualene metabolites. Using rapid amplification of cDNA ends (RACE), we characterized the 5' end of SULT1C2 mRNA and used this information to generate constructs for promoter analysis. SQ1 and MVA increased reporter activity by ∼1.6- and 3-fold, respectively, from a construct beginning 49 base pairs (bp) upstream from the longest 5'-RACE product (-3140:-49). Sequence deletions from this construct revealed a hepatocyte nuclear factor 1 (HNF1) element (-2558), and mutation of this element reduced basal (75%) and MVA-induced (30%) reporter activity and attenuated promoter activation following overexpression of HNF1α or 1β. However, the effects of SQ1 were localized to a more proximal promoter region (-281:-49). Collectively, our findings demonstrate that cholesterol biosynthetic intermediates influence SULT1C2 expression in rat primary hepatocytes. Further, HNF1 appears to play an important role in mediating basal and MVA-induced SULT1C2 transcription.

Glutaredoxin mediated redox effects of coenzyme Q10 treatment in type 1 and type 2 diabetes patients

The possible beneficial effects of coenzyme Q10 (CoQ10) supplementation on disease progression and oxidant status in diabetes remains debated. In the present study, patients with type 1 and type 2 diabetes were treated with oral CoQ10, 100 mg twice daily for 12 weeks. We assessed total antioxidant capacity, intra- and extracellular levels of the redox regulating protein glutaredoxin 1 (Grx1), CoQ10, oxidized LDL-cholesterol, lipid profile and HbA1c. We have previously shown that extracellular Grx1 is increased in patients with type 2 diabetes compared to healthy subjects. In the present study, CoQ10 treatment significantly decreased serum Grx1 activity as well as total antioxidant capacity independent of type of diabetes, indicating an improvement to a less oxidized extracellular environment. The effect on serum Grx1 activity was more prominent in patients not on statin treatment. Conversely, intracellular Grx1 activity as well as mRNA levels increased independent of statin treatment. There was a significant improvement in oxidized LDL-cholesterol and lipid profile, with a tendency to improved metabolic control (HbA1c). Additionally, we describe for the first time that CoQ10 is a direct substrate for glutathione, and that Grx1 catalyzes this reaction, thus presenting a novel mechanism for CoQ10 reduction which could explain our findings of an increased intracellular Grx1. In conclusion, 12 weeks CoQ10 treatment significantly improved the extracellular redox balance and lipid profile, indicating that prolonged treatment may have beneficial effects also on clinical outcome in diabetes.

Molecular and Genetic Studies ofFusariumTrichothecene Biosynthesis: Pathways, Genes, and Evolution

Trichothecenes are a large family of sesquiterpenoid secondary metabolites of Fusarium species (e.g., F. graminearum) and other molds. They are major mycotoxins that can cause serious problems when consumed via contaminated cereal grains. In the past 20 years, an outline of the trichothecene biosynthetic pathway has been established based on the results of precursor feeding experiments and blocked mutant analyses. Following the isolation of the pathway gene Tri5 encoding the first committed enzyme trichodiene synthase, 10 biosynthesis genes (Tri genes; two regulatory genes, seven pathway genes, and one transporter gene) were functionally identified in the Tri5 gene cluster. At least three pathway genes, Tri101 (separated alone), and Tri1 and Tri16 (located in the Tri1-Tri16 two-gene cluster), were found outside of the Tri5 gene cluster. In this review, we summarize the current understanding of the pathways of biosynthesis, the functions of cloned Tri genes, and the evolution of Tri genes, focusing on Fusarium species.

Effects of widely used drugs on micronutrients: a story rarely told

Vitamins and trace elements are essential to the body, however, deficiencies are frequently observed in the general population. Diet is mostly responsible for these deficiencies but drugs also may play a significant role by influencing their metabolism. These effects are rarely assessed in clinical practice, in part because of limited data available in the literature. Drug-induced micronutrient depletions, however, may be the origin of otherwise unexplained symptoms that might sometimes influence medication compliance. We present various examples of widely prescribed drugs that can precipitate micronutrient deficiencies. This review aims at sensitizing physicians on drug-micronutrient interactions. High-risk population groups also are presented and supplementation protocols are suggested.

Mitochondrial coenzyme Q10 determination by isotope-dilution liquid chromatography-tandem mass spectrometry

BACKGROUND

Coenzyme Q10 (CoQ10) is an essential part of the mitochondrial respiratory chain. Unlike most other respiratory chain disorders, CoQ10 deficiency is potentially treatable. We aimed to develop and validate an accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of mitochondrial CoQ10 in clinical samples.

METHODS

We used mitochondria isolated from muscle biopsies of patients (n = 166) suspected to have oxidative phosphorylation deficiency. We also used fibroblast mitochondria from 1 patient with CoQ10 deficiency and 3 healthy individuals. Samples were spiked with nonphysiologic CoQ10-[(2)H6] internal standard, extracted with 1-propanol and with ethanol and hexane (2 mL/5 mL), and CoQ10 quantified by LC-MS/MS. The method and sample stability were validated. A reference interval was established from the patient data.

RESULTS

The method had a limit of quantification of 0.5 nmol/L. The assay range was 0.5-1000 nmol/L and the CVs were 7.5%-8.2%. CoQ10 was stable in concentrated mitochondrial suspensions. In isolated mitochondria, the mean ratio of CoQ10 to citrate synthase (CS) activity (CoQ10/CS) was 1.7 nmol/U (95% CI, 1.6-1.7 nmol/U). We suggest a CoQ10/CS reference interval of 1.1-2.8 nmol/U for both sexes and all ages. The CoQ10/CS ratio was 5-fold decreased in fibroblast mitochondria from a patient with known CoQ10 deficiency due to recessive prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2) mutations.

CONCLUSIONS

Normalization of mitochondrial CoQ10 concentration against citrate synthase activity is likely to reflect most accurately the CoQ10 content available for the respiratory chain. Our assay and the established reference range should facilitate the diagnosis of respiratory chain disorders and treatment of patients with CoQ10 deficiency.

Transcriptional and posttranscriptional inhibition of HMGCR and PC biosynthesis by geraniol in 2 Hep-G2 cell proliferation linked pathways

Geraniol, present in the essential oils of many aromatic plants, has in vitro and in vivo antitumor activity against several cell lines. We investigated the effects of geraniol on lipid metabolic pathways involved in Hep-G2 cell proliferation and found that geraniol inhibits the mevalonate pathway, phosphatidylcholine biosynthesis, cell growth, and cell cycle progression (with an arrest occurring at the G0/G1 interphase) and increases apoptosis. The expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), the rate-limiting step in cholesterol synthesis, was inhibited at the transcriptional and posttranscriptional levels, as assessed by real-time RT-PCR, Western blots, and [(14)C]HMG-CoA-conversion radioactivity assays. That geraniol decreased cholesterogenesis but increased the incorporation of [(14)C]acetate into other nonsaponifiable metabolites indicated the existence of a second control point between squalene and cholesterol involved in redirecting the flow of cholesterol-derived carbon toward other metabolites of the mevalonate pathway. That exogenous mevalonate failed to restore growth in geraniol-inhibited cells suggests that, in addition to the inhibition of HMGCR, other dose-dependent actions exist through which geraniol can impact the mevalonate pathway and consequently inhibit cell proliferation. These results suggest that geraniol, a nontoxic compound found in many fruits and herbs, exhibits notable potential as a natural agent for combatting cancer and (or) cardiovascular diseases.

Influence of liver-X-receptor on tissue cholesterol, coenzyme Q and dolichol content

The organ content of the mevalonate pathway lipids was investigated in liver-X-receptor (LXR) α, β and double knock-out mice. An extensive or moderate increase of total cholesterol in the double KO mice was found in all organs elicited by the increase of the esterified form. In LXRα and double KO mice, coenzyme Q (CoQ) was decreased in liver and increased in spleen, thymus and lung, while dolichol was increased in all organs investigated. This effect was confirmed using LXR- agonist GW 3965. Analysis of CoQ distribution in organelles showed that the modifications are present in all cellular compartments and that the increase of the lipid in mitochondria was the result of a net increase of CoQ without changing the number of mitochondria. It appears that LXR influences not only cellular cholesterol homeostasis but also the metabolism of CoQ and dolichol, in an indirect manner.

Geraniol and simvastatin show a synergistic effect on a human hepatocarcinoma cell line

Simvastatin is a competitive inhibitor of 3-hydroxymethylglutaryl coenzyme A reductase activity, whereas geraniol is a monoterpene with multiple pharmacologic effects on mevalonate metabolism. Both of them inhibit growth and proliferation of many cell lines. The present study was designed to determine the action of geraniol, in combination with simvastatin, by assessing their effects in vitro on human hepatocarcinoma cell line (Hep G2). The treatment of Hep G2 cells with concentrations of simvastatin or geraniol that did not inhibit cell proliferation (5 µmol·l⁻¹ of simvastatin and 50 µmol·l⁻¹ of geraniol) resulted in a significant inhibition of cell proliferation. We also examined the effect of simvastatin, geraniol and the combination of both on the biosynthesis of lipids from [¹⁴C]-acetate. Our results demonstrate that the combination of simvastatin and geraniol synergistically inhibited cholesterol biosynthesis and proliferation of Hep G2 cell line, contributing to a better understanding of the action of a component of essential oils targeting a complex metabolic pathway, which would improve the use of drugs or their combination in the fight against cancer and/or cardiovascular diseases.

Regulation of trichothecene biosynthesis in Fusarium: recent advances and new insights

Trichothecenes are toxic secondary metabolites produced by filamentous fungi mainly belonging to the Fusarium genus. Production of these mycotoxins occurs during infection of crops and is a threat to human and animal health. Although the pathway for biosynthesis of trichothecenes is well established, the regulation of the Tri genes implicated in the pathway remains poorly understood. Most of the Tri genes are gathered in a cluster which contains two transcriptional regulators controlling the expression of the other Tri genes. The regulation of secondary metabolites biosynthesis in most fungal genera has been recently shown to be controlled by various regulatory systems in response to external environment. The control of the "Tri cluster" by non-cluster regulators in Fusarium was not clearly demonstrated until recently. This review covers the recent advances concerning the regulation of trichothecene biosynthesis in Fusarium and highlights the potential implication of various general regulatory circuits. Further studies on the role of these regulatory systems in the control of trichothecene biosynthesis might be useful in designing new strategies to reduce mycotoxin accumulation.

Impact of High-Dose Statin Pretreatment in Patients with Stable Angina during Off-Pump Coronary Artery Bypass

BACKGROUND

Periprocedural treatment with high-dose statins is known to have cardioprotective and pleiotropic effects, such as anti-thrombotic and anti-inflammatory actions. We aimed to assess the efficacy of high-dose rosuvastatin loading in patients with stable angina undergoing off-pump coronary artery bypass grafting (OPCAB).

MATERIALS AND METHODS

A total of 142 patients with stable angina who were scheduled to undergo surgical myocardial revascularization were randomized to receive either pre-treatment with 60-mg rosuvastatin (rosuvastatin group, n=71) or no pre-treatment (control group, n=71) before OPCAB. The primary endpoint was the 30-day incidence of major adverse cardiac events (MACEs). The secondary endpoint was the change in the degree of myocardial ischemia as evaluated with creatine kinase-myocardial band (CK-MB) and troponin T (TnT).

RESULTS

There were no significant intergroup differences in preoperative risk factors or operative strategy. MACEs within 30 days after OPCAB occurred in one patient (1.4%) in the rosuvastatin group and four patients (5.6%) in the control group, respectively (p=0.37). Preoperative CK-MB and TnT were not different between the groups. After OPCAB, the mean maximum CK-MB was significantly higher in the control group (rosuvastatin group 10.7±9.75 ng/mL, control group 14.6±12.9 ng/mL, p=0.04). Furthermore, the mean levels of maximum TnT were significantly higher in the control group (rosuvastatin group 0.18±0.16 ng/mL, control group 0.39±0.70 ng/mL, p=0.02).

CONCLUSION

Our findings suggest that high-dose rosuvastatin loading before OPCAB surgery did not result in a significant reduction of 30-day MACEs. However, high-dose rosuvastatin reduced myocardial ischemia after OPCAB.

Nogo-B receptor is necessary for cellular dolichol biosynthesis and protein N-glycosylation

Dolichol monophosphate (Dol-P) functions as an obligate glycosyl carrier lipid in protein glycosylation reactions. Dol-P is synthesized by the successive condensation of isopentenyl diphosphate (IPP), with farnesyl diphosphate catalysed by a cis-isoprenyltransferase (cis-IPTase) activity. Despite the recognition of cis-IPTase activity 40 years ago and the molecular cloning of the human cDNA encoding the mammalian enzyme, the molecular machinery responsible for regulating this activity remains incompletely understood. Here, we identify Nogo-B receptor (NgBR) as an essential component of the Dol-P biosynthetic machinery. Loss of NgBR results in a robust deficit in cis-IPTase activity and Dol-P production, leading to diminished levels of dolichol-linked oligosaccharides and a broad reduction in protein N-glycosylation. NgBR interacts with the previously identified cis-IPTase hCIT, enhances hCIT protein stability, and promotes Dol-P production. Identification of NgBR as a component of the cis-IPTase machinery yields insights into the regulation of dolichol biosynthesis.

Polished rice as natural sources of cancer-preventing geranylgeranoic acid

Geranylgeranoic acid, a 20-carbon polyprenoic acid (all-trans 3,7,11,15-tetramethyl-2,4,6,10,14-hexadecatetraenoic acid) and its derivatives were previously developed as synthetic “acyclic retinoids” for cancer chemoprevention. Recently, we demonstrated the natural occurrence of geranylgeranoic acid in various medicinal herbs (Shidoji and Ogawa, 2004). In this present study, we present several lines of evidence to demonstrate that geranylgeranyl diphosphate taken in foods could be metabolized to GGA through geranylgeraniol and geranylgeranyl aldehyde via the following steps: 1) The conversion from geranylgeranyl diphosphate to geranylgeraniol was demonstrated to occur by the action of bovine intestinal alkaline phosphatase, with a K_m of 46.1 µM. 2) Geranylgeraniol oxidase-mediated conversion of geranylgeraniol to geranylgeranyl aldehyde was revealed in rat liver homogenates, which activity was mainly localized in the mitochondrial fraction. The mitochondrial enzyme showed a K_m of 92.9 µM. 3) The conversion of geranylgeranyl aldehyde to geranylgeranoic acid by geranylgeranyl aldehyde dehydrogenase in rat liver homogenates was absolutely dependent on exogenously added NAD⁺ or NADP⁺. The K_m of the mitochondrial geranylgeranyl aldehyde dehydrogenase was 27.5 µM for geranylgeranyl aldehyde. Taken together, our data suggest that cancer preventive geranylgeranoic acid could be a physiological metabolite from commonly consumed foods.