Mevalonate Biosynthetic Pathway Research Articles

Application of Graph Models to the Identification of Transcriptomic Oncometabolic Pathways in Human Hepatocellular Carcinoma.

Whole-tissue transcriptomic analyses have been helpful to characterize molecular subtypes of hepatocellular carcinoma (HCC). Metabolic subtypes of human HCC have been defined, yet whether these different metabolic classes are clinically relevant or derive in actionable cancer vulnerabilities is still an unanswered question. Publicly available gene sets or gene signatures have been used to infer functional changes through gene set enrichment methods. However, metabolism-related gene signatures are poorly co-expressed when applied to a biological context. Here, we apply a simple method to infer highly consistent signatures using graph-based statistics. Using the Cancer Genome Atlas Liver Hepatocellular cohort (LIHC), we describe the main metabolic clusters and their relationship with commonly used molecular classes, and with the presence of TP53 or CTNNB1 driver mutations. We find similar results in our validation cohort, the LIRI-JP cohort. We describe how previously described metabolic subtypes could not have therapeutic relevance due to their overall downregulation when compared to non-tumoral liver, and identify N-glycan, mevalonate and sphingolipid biosynthetic pathways as the hallmark of the oncogenic shift of the use of acetyl-coenzyme A in HCC metabolism. Finally, using DepMap data, we demonstrate metabolic vulnerabilities in HCC cell lines.

A lactate-SREBP2 signaling axis drives tolerogenic dendritic cell maturation and promotes cancer progression.

Conventional dendritic cells (DCs) are essential mediators of antitumor immunity. As a result, cancers have developed poorly understood mechanisms to render DCs dysfunctional within the tumor microenvironment (TME). After identification of CD63 as a specific surface marker, we demonstrate that mature regulatory DCs (mregDCs) migrate to tumor-draining lymph node tissues and suppress DC antigen cross-presentation in trans while promoting T helper 2 and regulatory T cell differentiation. Transcriptional and metabolic studies showed that mregDC functionality is dependent on the mevalonate biosynthetic pathway and its master transcription factor, SREBP2. We found that melanoma-derived lactate activates SREBP2 in tumor DCs and drives conventional DC transformation into mregDCs via homeostatic or tolerogenic maturation. DC-specific genetic silencing and pharmacologic inhibition of SREBP2 promoted antitumor CD8+ T cell activation and suppressed melanoma progression. CD63+ mregDCs were found to reside within the lymph nodes of several preclinical tumor models and in the sentinel lymph nodes of patients with melanoma. Collectively, this work suggests that a tumor lactate-stimulated SREBP2-dependent program promotes CD63+ mregDC development and function while serving as a promising therapeutic target for overcoming immune tolerance in the TME.

A Phase 1 Study of Adding Pitavastatin to Venetoclax-Based Therapy in AML and CLL/SLL

Statins (HMG-CoA-reductase inhibitors) are drugs used widely for the treatment of high cholesterol and are generally well-tolerated. There has been increasing interest in repurposing statins for oncology based on the recognition that many cancer cells are “addicted” to the mevalonate biosynthetic pathway (Iannelli et al, 2017; Juarez and Fruman 2021). We have shown that statins increase expression of the pro-apoptotic BCL2 family member PUMA (Lee at al, 2018). We have strong pre-clinical evidence that statins improve responses to the BCL2 inhibitor venetoclax (VEN) in cell line models and ex vivo primary patient specimens from patients with both chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) (Lee et al, 2018). Additionally, retrospective review of patients enrolled into the early clinical trials of VEN in CLL revealed improved responses to VEN (complete remission [CR] and progression-free survival) in the patients who were concurrently on a statin medication (Lee et al, 2018). These retrospective analyses may underestimate the potential of statins for leukemia therapy, as the statin drugs most commonly prescribed for hypercholesterolemia are not pharmacologically optimized for oncology (Abdullah et al., 2018). We developed a phase 1 study of adding pitavastatin (PIT) to VEN-based therapy in patients with AML and CLL/small lymphocytic lymphoma (SLL) (NCT04512105). AML patients were eligible if receiving induction therapy with azacitidine (AZA) and VEN per standard of care. CLL/SLL patients could receive either VEN with obinutuzumab (O) or rituximab. A 3+3 design was employed. Dose level 1 was PIT 2 mg daily, and dose level 2 (DL2) was 4 mg daily. These doses are consistent with the doses used for the treatment of hypercholesterolemia. Those enrolling at DL2 had a creatinine clearance of 60 mL/min or higher based on the prescribing information for pitavastatin. Patients already on statins for the treatment for hypercholesterolemia were allowed; these patients stopped their prescribed statin for 72 hours prior to initiation of PIT. PIT started after patients completed VEN ramp-up and had been on a stable VEN dose for at least 5 days. Primary objectives were assessing safety and tolerability and determining the recommended phase 2 dose of PIT in combination with VEN-based therapies. Secondary objectives included CR rates. Exploratory objectives included performing BH3 profiling on pretreatment and post-treatment blood samples to assess whether add-on treatment with PIT increases apoptotic priming, as seen in preclinical models (Lee et al, 2018). 14 patients signed informed consent. 6 were deemed ineligible. 2 withdrew consent prior to starting PIT therapy. 6 patients received PIT on study. 2 patients had AML and received AZA+VEN. 2 patients had CLL, and 2 patients had SLL. The CLL/SLL patients all received VEN+O. Grade 1 myalgia was reported in one subject on the 4mg PIT dose. 1 patient experienced a grade 1 increase in AST on the 4mg dose. Another patient had grade 1 elevation in bilirubin and alkaline phosphatase at the 4 mg dose. Grade 3-4 toxicities included leukopenia, neutropenia (1 case of febrile neutropenia, grade 3), anemia, and thrombocytopenia. Cycle 1 was defined as the dose-limiting toxicity (DLT) period, and no hematologic toxicities occurred during the DLT period. 1 patient had grade 3 pancreatitis, but this was felt to be unrelated to therapy or disease (also outside the DLT period). No grade 5 toxicities occurred while on study therapy. Toxicities were overall felt to be similar to patients receiving VEN-based therapy in standard clinical practice. All evaluable patients (n=5) achieved clinical CR. 1 patient with SLL is awaiting re-staging at the time of this abstract. Correlative studies are ongoing. In 2 patient peripheral blood samples analyzed, the % blasts (for an AML sample) and % CD5+ B-cells (for a CLL sample) were reduced 24 hours after PIT dosing compared to prior to any treatment and before PIT/after VEN ramp-up. Based on the tolerability of PIT and encouraging clinical outcomes, a phase 2 study is being planned to better assess the efficacy of adding PIT to VEN-based therapies in AML and CLL/SLL.

Abstract 2892: A SREBF2-dependent genetic program drives a novel immunotolerant dendritic cell population that supports cancer progression

Abstract The development of immune responses to cancers are crucially dependent upon effective antigen cross-presentation by local dendritic cell (DC) populations. Indeed, DC-mediated T cell stimulation is essential for generating responses to anti-PD-1 immunotherapy. Tumors have been shown to hijack DC function in a process broadly known as tolerization. Despite the significant implications of this process on the modulation of anti-tumor immunity, the underlying mechanisms of this process remain unclear. We have identified a unique population of DCs in transgenic models of both melanoma and non-small cell lung cancer that arise within the tumor microenvironment and migrate to the draining lymph node (LN) tissues during the course of disease progression. RNAseq and flow cytometry studies revealed this DC population to exhibit a unique CD63 surface marker, enabling us to determine this subset to drive regulatory T cell (Treg) and TH2 expansion while suppressing conventional DC-mediated activation of CD8+ T cell responses, even at rare numbers. Additional transcriptional and metabolic studies showed these CD63+ DCs to be a subset of the previously identified 'mature DCs enriched in immunoregulatory molecules' (mregDC) population and to exhibit both enhanced activity of the mevalonate biosynthetic pathway as well as increased lipid stores and dependence on fatty acid oxidation. Inhibitor studies confirmed that mevalonate biosynthesis drives CD63+ mregDC-mediated immune tolerance while scATACseq studies have identified open regulatory elements in CD63+ mregDCs associated with key rate-limiting genes associated with the mevalonate pathway. Additional lineage analysis revealed the CD63+ mregDC population to evolve primarily from type 2 conventional DCs in vivo. Both DC-specific genetic deletion of the SREBF2 master transcription factor as well as SREBP2 pharmacologic inhibition suppresses melanoma progression while enhancing tumor CD8+ T cell infiltration. Adoptive transfer of CD63+ mregDCs enhances melanoma metastases and promotes the accumulation of Tregs in draining LN tissues. scRNAseq studies as well as spatial transcriptomic analysis has confirmed this same DC population in the sentinel LN tissues of melanoma patients. We propose that this novel DC subset represents a key target for augmenting anti-tumor immune responses and suppressing metastatic progression. Ongoing work is focused on dissecting the regulatory pathways dictating the transcriptional program of CD63+ mregDCs and developing a CD11c-CD63 bispecific depletion antibody for further pre-clinical testing. Citation Format: Michael P. Plebanek, Yue Xue, Y-Van Nguyen, Nicholas C. DeVito, Xueying Wang, Georgia Beasley, Nagendra Yarla, Bala Thievanthiran, Brent A. Hanks. A SREBF2-dependent genetic program drives a novel immunotolerant dendritic cell population that supports cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2892.

정유를 구성하는 분자들의 특성에 대한 양자화학적 연구

In order to understand the characteristics of molecules constituting essential oil, ab intio calculations were carried out for 18 molecules produced by the Mevalonate biosynthetic pathway. As a result of the calculation, we proposed HOMO and LUMO, which are useful for predicting the site of nucleophilic, electrophilic, and radical reaction. And the nucleophilicity of essential oil molecules calculated by HOMO and LUMO energies was greater than the electrophilicity also. It showed that a good linear relationship between electronic chemical potential and electro accepting power. And we have reported the dipole moment and ㅔpolarizability, which are physical properties of essential oil molecules. In the reaction of molecules constituting essential oil with oxygen, the values ​​of the reaction Gibbs energy were –2814.14kcal/mol ~ -2542.33kcal/mol and the reaction enthalpy ranged -2875.03kcal/mol to -2605.94 kcal/mol. From this, we concluded that the reaction with oxygen occurs spontaneously with work productivity and is an exothermic process. These results will be helpful for future molecular studies of essential oils.

Inhibition of the 3-hydroxy-3-methyl-glutaryl-CoA reductase diminishes the survival and size of chondrocytes during orofacial morphogenesis in zebrafish.

The 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) is the enzyme controlling the rate-limiting step in the synthesis of cholesterol, sterols, and isoprenoids in the mevalonate biosynthetic pathway. Impaired function of HMGCR in zebrafish produces craniofacial malformations and orofacial cleft, mainly affecting the post-migratory neural crest cells with little earlier effect. Here we investigate morphogenetic and cellular mechanisms underlying the generation of these malformations. The morphology of chondrocytes in the lower jaw and the proliferation/apoptosis in the ethmoid plate were analysed in hmgcr1b mutants and in embryos treated with atorvastatin. In the ceratohyal of treated embryos, we measured the number and dimensions of chondrocytes. In the ethmoid plate, we performed proliferation and apoptosis assays to quantify the number of cells undergoing each process in both hmgcr1b mutants and pharmacologically treated embryos. All embryos were imaged using confocal microscopy and processed to obtain maximum intensity z-projection. The shortening of the ceratohyal is produced by a moderate reduction in the number of cells combined with isometric shrinkage of the chondrocytes. At the same time, the shortening of the ethmoid plate is due to a combination of a slightly diminished proliferation with massive abnormal apoptosis at the proliferation front. HMGCR function is necessary for the normal survival and morphology of chondrocytes during condensation and chondrogenesis in the developing palate and jaw. Further studies are required to establish the pathways through which HMGCR acts on apoptosis, proliferation, and cell size during normal craniofacial development.

Heterologous Expression of Three Transcription Factors Differently Regulated Astragalosides Metabolic Biosynthesis in Astragalus membranaceus Hairy Roots.

Astragalus membranaceus has been used as a highly popular Chinese herbal medicine for centuries. Triterpenoids, namely astragalosides I, II, III, and IV, represent the main active compounds in this plant species. Transcription factors have a powerful effect on metabolite biosynthesis in plants. We investigated the effect of the Arabidopsis MYB12, production of anthocyanin pigment 1 (PAP1), and maize leaf color (LC) transcription factors in regulating the synthesis of astragaloside metabolites in A. membranaceus. Overexpression of these transcription factors in hairy roots differentially up-regulated these active compounds. Specifically, the overexpression of LC resulted in the accumulation of astragalosides I–IV. The content of astragalosides I and IV were, in particular, more highly accumulated. Overexpression of MYB12 increased the accumulation of astragaloside I in transgenic hairy roots, followed by astragaloside IV, and overexpression of PAP1 resulted in the increased synthesis of astragalosides I and IV. In addition, we found that overexpression of PAP1 together with LC increased astragaloside III levels. At the transcriptional level, several key genes of the mevalonate biosynthetic pathway, especially HMGR1, HMGR2, and HMGR3, were up-regulated differentially in response to these transcription factors, resulting in astragaloside synthesis in the hairy roots of A. membranaceus. Overall, our results indicated that heterologous expression of Arabidopsis MYB12, PAP1, and maize LC differentially affected triterpenoids biosynthesis, leading to the increased biosynthesis of active compounds in A. membranaceus.

Reduction in Pathogenicity in Yeast-like Fungi by Farnesol in Quail Model.

Simple SummaryDespite the discoveries of new therapeutic antimycotics, the development of drug resistance is still the main clinical challenge in the treatment of mycoses. Data on the presence of new phytopreparations, along with the direct fungicidal effects that interfere with the resistance of fungal pathogens located in the biofilm, are of great interest. The use of these compounds as monotherapies or in combination with known antimycotics may be an effective strategy for preventing and/or destroying Candida biofilms found on the surface of biomedical devices and in vivo. The action mechanisms of farnesol in fungi have yet to be fully understood, but they are complex and likely include several mechanisms such as growth inhibition and apoptosis promotion.Candida albicans was the first eukaryotic microorganism to exhibit quorum-sensing through the secretion of the sesquiterpene E, farnesol. This molecule is generated by dephosphorylation of farnesyl pyrophosphate in the mevalonate biosynthetic pathway in mammalian and yeast cells. Exogenous farnesol inhibits yeast-to-hyphal formation in a concentration- and time-dependent manner at the earliest stage of hyphal development. Much research has been devoted to studying the role of farnesol as an inhibitor of hyphal morphogenesis; however, little research has been published regarding the in vivo impacts of farnesol on fungal virulence and the development of Candida infection. While other studies have examined the impact of multiple doses of farnesol in addition to antimycotics, we hypothesize that C. albicans treated with a single dose of this quorum-sensing molecule could reduce fungal virulence in a quail model.

Comparative transcriptome analysis reveals sesquiterpenoid biosynthesis among 1-, 2- and 3-year old Atractylodes chinensis

BackgroundAtractylodes chinensis (DC.) Koidz is a well-known medicinal plant containing the major bioactive compound, atractylodin, a sesquiterpenoid. High-performance liquid chromatography (HPLC) analysis demonstrated that atractylodin was most abundant in 3-year old A. chinensis rhizome, compared with those from 1- and 2-year old rhizomes, however, the molecular mechanisms underlying accumulation of atractylodin in rhizomes are poorly understood.ResultsIn this study, we characterized the transcriptomes from rhizomes of 1-, 2- and 3-year old (Y1, Y2 and Y3, respectively) A. chinensis, to identify differentially expressed genes (DEGs). We identified 240, 169 and 131 unigenes encoding the enzyme genes in the mevalonate (MVA), methylerythritol phosphate (MEP), sesquiterpenoid and triterpenoid biosynthetic pathways, respectively. To confirm the reliability of the RNA sequencing analysis, eleven key gene encoding factors involved in the sesquiterpenoid and triterpenoid biosynthetic pathway, as well as in pigment, amino acid, hormone and transcription factor functions, were selected for quantitative real time PCR (qRT-PCR) analysis. The results demonstrated similar expression patterns to those determined by RNA sequencing, with a Pearson’s correlation coefficient of 0.9 between qRT-PCR and RNA-seq data. Differential gene expression analysis of rhizomes from different ages revealed 52 genes related to sesquiterpenoid and triterpenoid biosynthesis. Among these, seven DEGs were identified in Y1 vs Y2, Y1 vs Y3 and Y2 vs Y3, of which five encoded four key enzymes, squalene/phytoene synthase (SS), squalene-hopene cyclase (SHC), squalene epoxidase (SE) and dammarenediol II synthase (DS). These four enzymes directly related to squalene biosynthesis and subsequent catalytic action. To validate the result of these seven DEGs, qRT-PCR was performed and indicated most of them displayed lower relative expression in 3-year old rhizome, similar to transcriptomic analysis.ConclusionThe enzymes SS, SHC, SE and DS down-regulated expression in 3-year old rhizome. This data corresponded to the higher content of sesquiterpenoid in 3-year old rhizome, and confirmed by qRT-PCR. The results of comparative transcriptome analysis and identified key enzyme genes laid a solid foundation for investigation of production sesquiterpenoid in A. chinensis.

Characterization of the Ergosterol Biosynthesis Pathway in Ceratocystidaceae.

Terpenes represent the biggest group of natural compounds on earth. This large class of organic hydrocarbons is distributed among all cellular organisms, including fungi. The different classes of terpenes produced by fungi are mono, sesqui, di- and triterpenes, although triterpene ergosterol is the main sterol identified in cell membranes of these organisms. The availability of genomic data from members in the Ceratocystidaceae enabled the detection and characterization of the genes encoding the enzymes in the mevalonate and ergosterol biosynthetic pathways. Using a bioinformatics approach, fungal orthologs of sterol biosynthesis genes in nine different species of the Ceratocystidaceae were identified. Ergosterol and some of the intermediates in the pathway were also detected in seven species (Ceratocystis manginecans, C. adiposa, Huntiella moniliformis, Thielaviopsis punctulata, Bretziella fagacearum, Endoconidiophora polonica and Davidsoniella virescens), using gas chromatography-mass spectrometry analysis. The average ergosterol content differed among different genera of Ceratocystidaceae. We also identified all possible terpene related genes and possible biosynthetic clusters in the genomes used in this study. We found a highly conserved terpene biosynthesis gene cluster containing some genes encoding ergosterol biosynthesis enzymes in the analysed genomes. An additional possible terpene gene cluster was also identified in all of the Ceratocystidaceae. We also evaluated the sensitivity of the Ceratocystidaceae to a triazole fungicide that inhibits ergosterol synthesis. The results showed that different members of this family behave differently when exposed to different concentrations of triazole tebuconazole.

De Novo Transcriptome Assembly of Two Microsorum Fern Species Identifies Enzymes Required for Two Upstream Pathways of Phytoecdysteroids

Microsorum species produce a high amount of phytoecdysteroids (PEs), which are widely used in traditional medicine in the Pacific islands. The PEs in two different Microsorum species, M. punctatum (MP) and M. scolopendria (MS), were examined using high-performance liquid chromatography (HPLC). In particular, MS produces a high amount of 20-hydroxyecdysone, which is the main active compound in PEs. To identify genes for PE biosynthesis, we generated reference transcriptomes from sterile frond tissues using the NovaSeq 6000 system. De novo transcriptome assembly after deleting contaminants resulted in 57,252 and 54,618 clean transcripts for MP and MS, respectively. The clean Microsorum transcripts for each species were annotated according to gene ontology terms, UniProt pathways, and the clusters of the orthologous group protein database using the MEGAN6 and Sma3s programs. In total, 1852 and 1980 transcription factors were identified for MP and MS, respectively. We obtained transcripts encoding for 38 and 32 enzymes for MP and MS, respectively, potentially involved in mevalonate and sterol biosynthetic pathways, which produce precursors for PE biosynthesis. Phylogenetic analyses revealed many redundant and unique enzymes between the two species. Overall, this study provides two Microsorum reference transcriptomes that might be useful for further studies regarding PE biosynthesis in Microsorum species.

Mesenchymal subtype neuroblastomas are addicted to TGF-\u03b2R2/HMGCR-driven protein geranylgeranylation

The identification of targeted agents with high therapeutic index is a major challenge for cancer drug discovery. We found that screening chemical libraries across neuroblastoma (NBL) tumor subtypes for selectively-lethal compounds revealed metabolic dependencies that defined each subtype. Bioactive compounds were screened across cell models of mesenchymal (MESN) and MYCN-amplified (MYCNA) NBL subtypes, which revealed the mevalonate and folate biosynthetic pathways as MESN-selective dependencies. Treatment with lovastatin, a mevalonate biosynthesis inhibitor, selectively inhibited protein prenylation and induced apoptosis in MESN cells, while having little effect in MYCNA lines. Statin sensitivity was driven by HMGCR expression, the rate-limiting enzyme for cholesterol synthesis, which correlated with statin sensitivity across NBL cell lines, thus providing a drug sensitivity biomarker. Comparing expression profiles from sensitive and resistant cell lines revealed a TGFBR2 signaling axis that regulates HMGCR, defining an actionable addiction in that leads to MESN-subtype-dependent apoptotic cell death.

Exploiting the Feedstock Flexibility of the Emergent Synthetic Biology Chassis Vibrio natriegens for Engineered Natural Product Production.

A recent goal of synthetic biology has been to identify new chassis that provide benefits lacking in model organisms. Vibrio natriegens is a marine Gram-negative bacterium which is an emergent synthetic biology chassis with inherent benefits: An extremely fast growth rate, genetic tractability, and the ability to grow on a variety of carbon sources (“feedstock flexibility”). Given these inherent benefits, we sought to determine its potential to heterologously produce natural products, and chose beta-carotene and violacein as test cases. For beta-carotene production, we expressed the beta-carotene biosynthetic pathway from the sister marine bacterium Vibrio campbellii, as well as the mevalonate biosynthetic pathway from the Gram-positive bacterium Lactobacillus acidophilus to improve precursor abundance. Violacein was produced by expressing a biosynthetic gene cluster derived from Chromobacterium violaceum. Not only was V. natriegens able to heterologously produce these compounds in rich media, illustrating its promise as a new chassis for small molecule drug production, but it also did so in minimal media using a variety of feedstocks. The ability for V. natriegens to produce natural products with multiple industrially-relevant feedstocks argues for continued investigations into the production of more complex natural products in this chassis.

Alzheimer’s Disease: Is a Dysfunctional Mevalonate Biosynthetic Pathway the Master-Inducer of Deleterious Changes in Cell Physiology?

The awareness is growing that the proteins amyloid-beta (Aβ) and tau are rather a result of Alzheimer’s disease (AD) than its cause. Similarly, doubt reigns about the degree of causality of high plasma cholesterol/lipids (the fat connection) and of prenylation. An important conceptual addition to the current lines of thinking is advanced here. It emerged from a comparative analysis, in evolutionary retrospect, of the characteristics of the mevalonate biosynthetic pathways in insects versus in vertebrates/mammals, and of the drastic effects of a declining titer of farnesol and, where present, its esters with juvenile hormone (JH) activity. A dysfunctional mevalonate biosynthetic pathway with farnesol at its very heart, can disturb “Golgicrine” activity, reduce mitochondrial multiplication, alter Ca2+-homeostasis, cause massive apoptosis in specific tissues, etc. These effects were already observed in insects in the 1960-70ties, when it became undeniably established that the fall to zero of the titer of the endogenous sesquiterpenoids farnesol and its JH esters is the direct inducer of complete metamorphosis. Such effects are remarkably similar in metamorphosing insects, and in the AD brain. In insects, administration of farnesol/JH temporarily prevents all cited changes. No such fall to zero in insects with incomplete metamorphosis, hence no massive apoptosis. Neither do vertebrates/mammals have a period in their development in which the mevalonate biosynthetic pathway in which farnesylpyrophosphate, farnesol and cholesterol are synthesized (in their brain inclusive), comes to a complete halt. Hence the difficulty of uncovering functions of farnesol itself other than just serving as an intermediate in the mevalonate pathway. The discovery (1999) that in the rodent and human brain farnesol potently blocks N-type Ca2+ channels, proving that the mevalonate pathway and farnesol play a key role in Ca2+-homeostasis, was a major breakthrough. This paper highlights its major consequences for AD research.

Mevalonate pathway activity as a determinant of radiation sensitivity in head and neck cancer.

Radioresistance is a major hurdle in the treatment of head and neck squamous cell carcinoma (HNSCC). Here, we report that concomitant treatment of HNSCCs with radiotherapy and mevalonate pathway inhibitors (statins) may overcome resistance. Proteomic profiling and comparison of radioresistant to radiosensitive HNSCCs revealed differential regulation of the mevalonate biosynthetic pathway. Consistent with this finding, inhibition of the mevalonate pathway by pitavastatin sensitized radioresistant SQ20B cells to ionizing radiation and reduced their clonogenic potential. Overall, this study reinforces the view that the mevalonate pathway is a promising therapeutic target in radioresistant HNSCCs.

Mode of Action of Farnesol, the "Noble Unknown" in Particular in Ca2+ Homeostasis, and Its Juvenile Hormone-Esters in Evolutionary Retrospect.

Farnesol, the sesquiterpenoid precursor of insect juvenile hormones (JH) that itself has JH activity, existed already long before animals and their hormones came into being. Although it is omnipresent in all eukaryotes, this molecule remains a “noble unknown” in cell physiology. It is neither documented as a hormone nor as another type of signaling molecule. To date, its function as an intermediate in the synthesis of squalene-cholesterol-steroids in chordates/vertebrates, and of the insect/arthropod JHs, esters of farnesol, in the mevalonate biosynthetic pathway is assumed to be the only one. This assumption neglects that already two decades ago, farnesol has been shown to be a potent endogenous inhibitor of N-type voltage-gated Ca2+ channels in some mammalian cell types. The tandem mevalonate pathway and Ca2+ channels originated early in eukaryotic evolution, and has since been well conserved, “promoting” it as a ubiquitous player in Ca2+ homeostasis in all eukaryotes. This paper accentuates how this drastic change in thinking gained momentum after the discovery by Paroulek and Sláma that the huge amounts of JH I in male accessory glands of the Cecropia moth, are actually synthesized in these glands themselves and not in the corpora allata, the hitherto assumed unique synthesis site of such compounds. In addition, MAG-JHs have no hormonal- but an exocrine function. Here we hypothesize that MAG-JHs may function in protecting the spermatozoa against toxic Ca2+ concentrations, and in enabling their flagellum to undulate. They may do so by acting through membrane receptors. Our novel paradigm assigns to farnesol/JHs a function of flexible hydrophobic molecular valves for restricting untimely Ca2+-passage through some types of canonical Ca2+channels, using covalently bound farnesyl- or geranyl-geranyl group attachment as well as GPCRs-G proteins all containing a prenyl group. The high rotatable bond count, and their horseshoe-shape are instrumental to their valve function. In our paradigm, Met/Tai and Gce, to date generally thought to be the (only) functional (nuclear) receptors for JHs, are classified as probable Ca2+-sensitive transcription factors. Some theoretical and practical considerations for possible applications in a medical context will be discussed.

Efficient production of lycopene in Saccharomyces cerevisiae by enzyme engineering and increasing membrane flexibility and NAPDH production.

Lycopene is a red carotenoid pigment with strong antioxidant activity. Saccharomyces cerevisiae is considered a promising host to produce lycopene, but lycopene toxicity is one of the limiting factors for high-level production. In this study, we used heterologous lycopene biosynthesis genes crtE and crtI from Xanthophyllomyces dendrorhous and crtB from Pantoea agglomerans for lycopene production in S. cerevisiae. The crtE, crtB, and crtI genes were integrated into the genome of S. cerevisiae CEN.PK2-1C strain, while deleting DPP1 and LPP1 genes to inhibit a competing pathway producing farnesol. Lycopene production was further improved by inhibiting ergosterol production via downregulation of ERG9 expression and by deleting ROX1 or MOT3 genes encoding transcriptional repressors for mevalonate and sterol biosynthetic pathways. To further increase lycopene production, CrtE and CrtB mutants with improved activities were isolated by directed evolution, and subsequently, the mutated genes were randomly integrated into the engineered lycopene-producing strains via delta-integration. To relieve lycopene toxicity by increasing unsaturated fatty acid content in cell membranes, the OLE1 gene encoding stearoyl-CoA 9-desaturase was overexpressed. In combination with the overexpression of STB5 gene encoding a transcription factor involved in NADPH production, the final strain produced up to 41.8mg/gDCW of lycopene, which is approximately 74.6-fold higher than that produced in the initial strain.

Reconstitution and substrate specificity for isopentenyl pyrophosphate of the antiviral radical SAM enzyme viperin

Viperin is a radical SAM enzyme that has been shown to possess antiviral activity against a broad spectrum of viruses; however, its molecular mechanism is unknown. We report here that recombinant fungal and archaeal viperin enzymes catalyze the addition of the 5'-deoxyadenosyl radical (5'-dA•) to the double bond of isopentenyl pyrophosphate (IPP), producing a new compound we named adenylated isopentyl pyrophosphate (AIPP). The reaction is specific for IPP, as other pyrophosphate compounds involved in the mevalonate biosynthetic pathway did not react with 5'-dA• Enzymatic reactions employing IPP derivatives as substrates revealed that any chemical change in IPP diminishes its ability to be an effective substrate of fungal viperin. Mutational studies disclosed that the hydroxyl group on the side chain of Tyr-245 in fungal viperin is the likely source of hydrogen in the last step of the radical addition, providing mechanistic insight into the radical reaction catalyzed by fungal viperin. Structure-based molecular dynamics (MD) simulations of viperin interacting with IPP revealed a good fit of the isopentenyl motif of IPP to the active site cavity of viperin, unraveling the molecular basis of substrate specificity of viperin for IPP. Collectively, our findings indicate that IPP is an effective substrate of fungal and archaeal viperin enzymes and provide critical insights into the reaction mechanism.

Alteration of Mevalonate Pathway in Rat Splenic Lymphocytes: Possible Role in Cytokines Secretion Regulated by L-Theanine

L-Theanine is a nonprotein amino acid in tea, and its immunomodulatory function has been confirmed. This study aimed to investigate the effect of L-theanine addition on cytokines secretion in rat splenic lymphocytes and explore its potential immunomodulatory effects on the mevalonate biosynthetic pathway. Our results showed that L-theanine treatment did not influence the proliferation and division indexes of the splenic lymphocytes subsets. Interestingly, L-theanine treatment had regulated the contents of IFN-γ, IL-2, IL-4, IL-10, IL-12, and TNF-α (P < 0.001) except IL-6 and upregulated the mRNA and protein expression of Ras-related protein Rap-1A (Rap1A), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), and farnesyl diphosphate synthase (FDPs) (P < 0.001). Additionally, there was a positive correlation between Rap1A and HMGCR proteins expression and IFN-γ, IL-4, and IL-6 levels. In conclusion, L-theanine regulated the secretion of cytokines probably by activating expression of Rap1A and HMGCR proteins involved in the mevalonate biosynthetic pathway in rat splenic lymphocytes. Therefore, L-theanine might be a promising potential drug candidate as immunopotentiator.

Acute phase reaction following bisphosphonates.

Bisphosphonates are effective in decreasing bone resorption, the incidence of fragility fracure, and pain from bone metastases. Although relatively well tolerated, the initial dose(s)of intravenous or oral monthly aminobisphosphonates can be associated with an acute phase response, a nonspecific physiologic reaction associated with increased levels of inflammatory cytokines, fever, and flu like symptoms including fatigue, nausea, and myalgia within 3 days of dosing and lasting 7 days or less. Nitrogen-BPs(N-BPs)inhibit osteoclast function by acting as potent inhibitors of the enzyme farnesyl diphosphate(FPP)synthase in the mevalonate biosynthetic pathway. Following an intravenous infusion or oral monthly BPs, transient uptake of N-BP into peripheral blood monocytes results in intracellular accumulation of isopentenyl diphosphate(IPP)due to FPP synthase inhibition. Recognition of IPP by γδT cells triggers their activation and expansion, resulting in the release of pro-inflammatory cytokines that cause the flulike symptoms of the acute phase reaction. There is trial evidence that its severity can be reduced by more than half with coadministration of acetaminophen, so the short-term use of these drugs to lessen the APR is advisable in patients receiving their first dosing of N-BPs. Levels of 25(OH)D were negatively correlated with the incidence and severity of APR. Vitamin D reduces the intensity of musculoskeletal pain after dosing of N-BPs for postmenopausal osteoporosis. APR has minimal impact on long-term adherence to therapy. It is less common in subjects who have previously used bisphosphonates. Information of APR to a patient is important before administration.