Regulation of the mevalonate pathway

Effects of Simvastatin on RBL-2H3 Cell Degranulation

Hypercholesterolemia is a major complication of arteriosclerosis. Mast cells in arteriosclerosis plaques induce inflammatory reactions and promote arterial sclerosis. In this study, we evaluated the pharmacological effects of simvastatin (SV)-3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors on the degranulation of rat basophilic leukemia (RBL)-2H3 cells, which are commonly used as mast cell models. SV significantly decreased the degranulation induced by three types of stimulation: antigen antibody reaction (Ag-Ab), thapsigargin (Tg) serosal endoplasmic reticulum calcium ATPase (SERCA) inhibitor, and A23187 calcium ionophore. SV had a stronger inhibitory effect on degranulation induced by Ag-Ab stimulation than the other two stimulations. However, SV did not inhibit increase of intracellular Ca²⁺ concentrations. Mevalonate or geranylgeraniol co-treatment with SV completely prevented the inhibitory effect of SV on the degranulation induced by these stimulations. Immunoblotting results showed that SV inhibited protein kinase C (PKC) delta translocation induced by Ag-Ab but not by Tg or A23187. SV induced a reduction in active Rac1, and actin filament rearrangement. In conclusion, SV inhibits RBL-2H3 cell degranulation by inhibiting downstream signaling pathways, including the sequential degranulation pathway. These inhibitory effects were completely reversed by the addition of geranylgeraniol and might be induced by changes in the translocation of the small guanosine 5'-triphosphatase (GTPase) families Rab and Rho, which are related to vesicular transport PKC delta translocation and actin filament formation, respectively. These changes are caused by the inhibition of HMG-CoA reductase by SV following the synthesis of geranylgeranyl pyrophosphates, which play important roles in the activation of small GTPases, Rab.

The Nox2-ROS-Nlrp3 Inflammasome Signaling Stimulates in the Hematopoietic Stem/Progenitor Cells Lipogenesis to Facilitate Membrane Lipid Raft Formation

Proliferation, metabolism, and migration of hematopoietic stem/progenitor cells (HSPCs) are coordinated by receptors expressed on outer cell membranes that are integrated into microdomains, known as membrane lipid rafts (MLRs). These structures float freely in the cell membrane bilayer and are enriched in cholesterol and sphingolipids for their functional integrity. Receptors, if expressed in MLRs, have prolonged occupancy on the cell surface and enhanced signaling power. Based on this, we have become interested in the regulation of synthesis of MLRs components in HSPCs. To address this, we tested the effect of selected factors that promote proliferation or migration and their potential involvement in the synthesis of MLRs components in HSPCs. Based on our previous research showing that HSPCs from Nox2-KO and Nlrp3-KO mice display a profound defect in MLRs formation, we focused on the role of Nox2-ROS-Nlrp3 inflammasome in regulating lipogenesis in HSPCs. We found that while at steady state conditions, Nox2-derived ROS is required for a proper expression of enzymes regulating lipogenesis, during inflammation, this effect is augmented by Nlrp3 inflammasome. Thus, our data sheds new light on the regulation of lipogenesis in HSPCs and the involvement of the Nox2-ROS-Nlrp3 inflammasome axis that differently regulates lipogenesis at steady state conditions and in response to inflammation, modulating MLRs-mediated responsiveness of these cells to external stimuli.

PI(4,5)P2 and Cholesterol: Synthesis, Regulation, and Functions

Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P₂) is the most abundant membrane phosphoinositide and cholesterol is an essential component of the plasma membrane (PM). Both lipids play key roles in a variety of cellular functions including as signaling molecules and major regulators of protein function. This chapter provides an overview of these two important lipids. Starting from a brief description of their structure, synthesis, and regulation, the chapter continues to describe the primary functions and signaling processes in which PI(4,5)P₂ and cholesterol are involved. While PI(4,5)P₂ and cholesterol can act independently, they often act in concert or affect each other's impact. The chapters in this volume on "Cholesterol and PI(4,5)P₂ in Vital Biological Functions: From Coexistence to Crosstalk" focus on the emerging relationship between cholesterol and PI(4,5)P₂ in a variety of biological systems and processes. In this chapter, the next section provides examples from the ion channel field demonstrating that PI(4,5)P₂ and cholesterol can act via common mechanisms. The chapter ends with a discussion of future directions.

Mitochondrial Genetic Background May Impact Statins Side Effects and Atherosclerosis Development in Familial Hypercholesterolemia

Heredity of familial hypercholesterolemia (FH) can present as a dominant monogenic disorder of polygenic origin or with no known genetic cause. In addition, the variability of the symptoms among individuals or within the same families evidence the potential contribution of additional factors than monogenic mutations that could modulate the development and severity of the disease. In addition, statins, the lipid-lowering drugs which constitute the first-line therapy for the disease, cause associated muscular symptoms in a certain number of individuals. Here, we analyze the evidence of the mitochondrial genetic variation with a special emphasis on the role of CoQ₁₀ to explain this variability found in both disease symptoms and statins side effects. We propose to use mtDNA variants and copy numbers as markers for the cardiovascular disease development of FH patients and to predict potential statin secondary effects and explore new mechanisms to identify new markers of disease or implement personalized medicine strategies for FH therapy.

Nitrogen Sources Affect the Long-Chain Polyunsaturated Fatty Acids Content in Thraustochytrium sp. RT2316-16

The psychrophilic marine microorganism Thraustochytrium sp. RT2316-16 can produce carotenoids as well as lipids containing the omega-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid and docosahexaenoic acid. This work reports on the effects of the composition of the culture medium, including certain amino acids, on growth and lipid synthesis by RT2316-16. Compared with the culture on glutamate, the use of lysine, alanine, or serine, increased the content of the omega-3 PUFA in total lipids. In the media that contained yeast extract, glutamate, and glucose, lipid accumulation occurred when organic ammonium was exhausted earlier than glucose. In contrast, lipid mobilization was promoted if glucose was exhausted while organic ammonium (supplied by yeast extract and glutamate) remained in the medium. The total content of carotenoids in the lipid-free biomass decreased during the first 12 to 24 h of culture, simultaneously with a decrease in the total lipid content of the biomass. The experimental data suggested a possible interrelationship between the metabolism of carotenoids and lipids. A high content of omega-3 PUFA in the total lipids could be obtained by growing the thraustochytrid in a medium with a low glucose concentration (6 g L^-1) and a high concentration of organic nitrogen (yeast extract 12 g L^-1; glutamate 1.06 g L^-1), after glucose was exhausted. These observations may guide the development of a strategy to enhance omega-3 PUFA in the biomass.

Methionine regulates self-renewal, pluripotency, and cell death of GIC through cholesterol-rRNA axis

BACKGROUND

Glioma-initiating cells (GICs) are the source of glioma cells that can self-renew, have pluripotency, and are treatment-resistant, so are the starting point for relapse and eventual death despite multimodality therapy. L-[methyl-¹¹C] methionine PET has observed high accumulation at the time of recurrence, it is important to understand the mechanism of tumor cell activation caused by the reorganization of methionine metabolism.  METHODS: We cultured cells in methionine-deprived culture medium for comprehensive analysis. Based on the obtained results, the possible target molecules were chemically inhibited and the respective markers were analyzed.

RESULTS

Methionine depletion markedly decreased proliferation and increased cell death of GICs. Decreased S-adenosyl-methionine, which is synthesized intracellularly by catalyzed by methionine adenosyltransferase using methionine, triggered the following: (i) global DNA demethylation, (ii) hyper-methylation of signaling pathways regulating pluripotency of stem cells, (iii) decreased expression of the core-genes and pluripotent markers of stem cells including FOXM1, SOX2, SOX4, PROM1, and OLIG2, (iv) decreased cholesterol synthesis and increased excretion mainly through decreased SREBF2, and (v) down-regulation of the large subunit of ribosomal protein configured 28S and ACA43, small nucleolar RNA guiding the pseudouridylation of 28S rRNA, which is essential for translation. In addition, inhibition of cholesterol synthesis with statin resulted in a phenotype similar to that of methionine depletion and decreases in stem cell markers and small nucleolar RNA ACA43. Moreover, suppression of FOXM1 decreased stem cell markers such as SOX4 and PROM1. The gene expression profile for cholesterol production was obtained from the Ivy Glioblastoma Atlas Project database and compared between tumor cells with relatively low methionine levels in areas of pseudopalisading arrangement around necrosis and tumor cells in the infiltrating region, showing that cells in the infiltrating region have higher capacity to produce cholesterol.

CONCLUSIONS

Methionine metabolism is closely related with self-renewal, pluripotency, and cell death in GICs through modification of cholesterol biosynthesis, especially in the SREBF2-FOXM1 and ACA43 axis with modification of rRNA.

Proteomic Analysis of a Hypervirulent Mutant of the Insect-Pathogenic Fungus Metarhizium anisopliae Reveals Changes in Pathogenicity and Terpenoid Pathways

Metarhizium anisopliae is a commercialized entomopathogenic fungus widely used for the control of insect pests. Significant efforts have been expended to screen and/or select for isolates that display increased virulence toward target insect hosts. UV-induced mutagenesis has resulted in the isolation of a number of hypervirulent M. anisopliae mutants; however, the underlying mechanisms that have led to the desired phenotype have yet to be characterized. Here, we performed a comparative proteomic analysis of an M. anisopliae UV-induced hypervirulent mutant (MaUV-HV) and its wild-type parent using tandem mass tag (TMT)-based quantitative proteomics. A total of 842 differentially abundant proteins were identified, with 360 being more abundant in the hypervirulent mutant and 482 in the wild-type parent. In terms of differential abundance, the critical pathways affected included those involved in secondary metabolite production, virulence, and stress response. In addition, a number of genes involved in terpenoid biosynthesis pathways were identified as significantly mutated in the MaUV-HV strain. In particular, mutations in the farnesyl pyrophosphate synthase (FPPS1) and geranylgeranyl diphosphate synthase (GGPPS5) genes were seen. The effects of the FPPS1 mutation were confirmed via the construction and characterization of a targeted gene knockout strain (ΔMaFPPS1). The overall effects of the mutations were increased resistance to UV stress, faster growth, and increased virulence. These results provide mechanistic insights and new avenues for modulating fungal virulence in efforts to increase the biological control potential of insect-pathogenic fungi. IMPORTANCE The mechanisms that underlie and contribute to microbial (fungal) virulence are known to be varied; however, the identification of contributing pathways beyond known virulence factors remains difficult. Using TMT-based proteomic analyses, changes in the proteomes of an M. anisopliae hypervirulent mutant and its wild-type parent were determined. These data revealed alterations in pathogenicity, stress, and growth/developmental pathways, as well as pathways not previously known to affect virulence. These include terpenoid pathways that can be manipulated to increase the efficacy of fungal insect biological control agents for increased sustainable pest control.

Mechanism Underlying Naringenin Hypocholesterolemic Effects: Involvement of Estrogen Receptor α Subtype

Naringenin (Nar) is one of major citrus flavonoids predominantly found in grapefruit and orange. In vivo studies have demonstrated Nar potential as a normolipidemic agent capable to reduce circulating cholesterol in hypercholesterolemic rabbits, rats, and patients, suggesting a new role for this molecule in cardiovascular disease prevention. Although Nar cholesterol-lowering effects are known, the underlying mechanisms have not yet been elucidated. Interestingly, Nar binds to the estrogen receptors (ERs), modulating both transcriptional and membrane-initiating signals. Although estrogen and ERs are deeply involved in lipid metabolism, no data are available regarding a putative role of these nuclear receptors as mediators of the hypocholesterolemic effect exerted by Nar. Thus, the aim of this work was to study the involvement of ERs in Nar-induced modulation of cholesterol metabolism. Results obtained in HepG2 cell line demonstrate that Nar can modulate the molecular network of cholesterol homeostasis. However, these effects were only partially dependent on the activity of estrogen receptor α. As a whole, our data highlight new molecular mechanisms by which Nar influences cholesterol metabolism, opening a new scenery about dietary impact on human health.

Bisphosphonate affects the behavioral responses to HCl by disrupting farnesyl diphosphate synthase in mouse taste bud and tongue epithelial cells

Little is known about the molecular mechanisms underlying drug-induced taste disorders, which can cause malnutrition and reduce quality of life. One of taste disorders is known adverse effects of bisphosphonates, which are administered as anti-osteoporotic drugs. Therefore, the present study evaluated the effects of risedronate (a bisphosphonate) on taste bud cells. Expression analyses revealed that farnesyl diphosphate synthase (FDPS, a key enzyme in the mevalonate pathway) was present in a subset of mouse taste bud and tongue epithelial cells, especially type III sour-sensitive taste cells. Other mevalonate pathway-associated molecules were also detected in mouse taste buds. Behavioral analyses revealed that mice administered risedronate exhibited a significantly enhanced aversion to HCl but not for other basic taste solutions, whereas the taste nerve responses were not affected by risedronate. Additionally, the taste buds of mice administered risedronate exhibited significantly lower mRNA expression of desmoglein-2, an integral component of desmosomes. Taken together, these findings suggest that risedronate may interact directly with FDPS to inhibit the mevalonate pathway in taste bud and tongue epithelial cells, thereby affecting the expression of desmoglein-2 related with epithelial barrier function, which may lead to alterations in behavioral responses to HCl via somatosensory nerves.

Functional and miRNA regulatory characteristics of INSIG genes highlight the key role of lipid synthesis in the liver of chicken (Gallus gallus)

The insulin-induced genes (INSIG1 and INSIG2) have been demonstrated to play a vital role in regulating lipid metabolism in mammals, however the function and regulation mechanism of them remains unknown in poultry. In this study, firstly the phylogenetic trees of INSIGs among various species were constructed and their subcellular locations were mapped in chicken LMH. Then the spatiotemporal expression profiles, over-expression and knockdown assays of chicken INSIGs were conducted. Furthermore, conservation of potential miRNA binding sites in INSIGs among species were analyzed, and the miRNA biological function and regulatory role were verified. The results showed that chicken INSIGs located in cellular endoplasmic reticulum, and were originated from the common ancestors of their mammalian counterparts. The INSIGs were widely expressed in all detected tissues, and their expression levels in the liver of chicken at 30 wk were significantly higher than that at 20 wk (P < 0.01). Over-expression of INSIGs led no significant increase in mRNA abundance of lipid metabolism-related genes and the contents of triacylglycerol (TG) and cholesterol (TC) in LMH cells. Knockdown of INSIG1 led to the decreased expressions of ACSL1, MTTP-L, ApoB, ApoVLDLII genes and TG, TC contents (P < 0.05). Knockdown of INSIG2 could significantly decrease the contents of TG and TC, and expressions of key genes related to the lipid metabolism (P < 0.05). Moreover, INSIG1 was directly targeted by both miR-130b-3p and miR-218-5p, and INSIG2 was directly targeted by miR-130b-3p. MiR-130b-3p mimic and miR-218-5p mimic treatment could significant decrease the mRNA and protein levels of INSIGs, mRNA levels of genes related to lipid metabolism, and the contents of TG and TC in LMH cells. The inhibition of miR-130b-3p and miR-218-5p on TG and TC contents could be restored by the overexpression of INSIGs, respectively. No significant alteration in expressions of sterol regulatory element binding protein (SREBPs) and SREBP cleavage-activating protein (SCAP) were observed when INSIGs were over-expressed. SCAP was down-regulated when INSIG1 was knocked down, while SREBP1 was down-regulated when INSIG2 was knocked down. Taken together, these results highlight the role of INSIG1 and INSIG2 in lipid metabolism and their regulatory mechanism in chicken.

TET2 deficiency sensitizes tumor cells to statins by reducing HMGCS1 expression

TET2 (ten-eleven-translocation) protein is a Fe(II)- and α-ketoglutarate-dependent dioxygenase that catalyzes DNA demethylation to regulate gene expression. While TET2 gene is frequently mutated in hematological cancer, its enzymatic activity is also compromised in various solid tumors. Whether TET2 deficiency creates vulnerability for cancer cells has not been studied. Here we reported that TET2 deficiency is associated with the change of lipid metabolism processes in acute myeloid leukemia (AML) patient. We demonstrate that statins, the inhibitors of β-Hydroxy β-methylglutaryl-CoA (HMG-CoA) reductase and commonly used cholesterol-lowering medicines, significantly sensitize TET2 deficient tumor cells to apoptosis. TET2 directly regulates the expression of HMG-CoA synthase (HMGCS1) by catalyzing demethylation on its promoter region, and conversely TET2 deficiency leads to significant down-regulation of HMGCS1 expression and the mevalonate pathway. Consistently, overexpression of HMGCS1 in TET2-deficient cells rescues statin-induced apoptosis. We further reveal that decrease of geranylgeranyl diphosphate (GGPP), an intermediate metabolite in the mevalonate pathway, is responsible for statin-induced apoptosis. GGPP shortage abolishes normal membrane localization and function of multiple small GTPases, leading to cell dysfunction. Collectively, our study reveals a vulnerability in TET2 deficient tumor and a potential therapeutic strategy using an already approved safe medicine.

Pharmacogenomics of lipid-lowering agents: the impact on efficacy and safety

Hyperlipidemia is a significant risk factor for cardiovascular disease morbidity and mortality. The lipid-lowering drugs are considered the cornerstone of primary and secondary prevention of atherosclerotic cardiovascular disease. Unfortunately, the lack of efficacy and associated adverse effects, ranging from mild-to-moderate to potentially life-threatening, lead to therapy discontinuation. Numerous reports support the role of gene polymorphisms in drugs' pharmacokinetic parameters and their associated adverse reactions. Therefore, this study aims to understand the pharmacogenomics of lipid-lowering drugs and the impact of genetic variants of key genes on the drugs' efficacy and toxicity. Indeed, genetically guided lipid-lowering therapy enhances overall safety, improves drug adherence and achieves long-term therapy.

Renal Cell Carcinoma as a Metabolic Disease: An Update on Main Pathways, Potential Biomarkers, and Therapeutic Targets

Clear cell renal cell carcinoma (ccRCC) is the most frequent histological kidney cancer subtype. Over the last decade, significant progress has been made in identifying the genetic and metabolic alterations driving ccRCC development. In particular, an integrated approach using transcriptomics, metabolomics, and lipidomics has led to a better understanding of ccRCC as a metabolic disease. The metabolic profiling of this cancer could help define and predict its behavior in terms of aggressiveness, prognosis, and therapeutic responsiveness, and would be an innovative strategy for choosing the optimal therapy for a specific patient. This review article describes the current state-of-the-art in research on ccRCC metabolic pathways and potential therapeutic applications. In addition, the clinical implication of pharmacometabolomic intervention is analyzed, which represents a new field for novel stage-related and patient-tailored strategies according to the specific susceptibility to new classes of drugs.

Clinical trials and promising preclinical applications of CRISPR/Cas gene editing

Treatment of genetic disorders by genomic manipulation has been the unreachable goal of researchers for many decades. Although our understanding of the genetic basis of genetic diseases has advanced tremendously in the last few decades, the tools developed for genomic editing were not efficient and practical for their use in the clinical setting until now. The recent advancements in the research of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas) systems offered an easy and efficient way to edit the genome and accelerated the research on their potential use in the treatment of genetic disorders. In this review, we summarize the clinical trials that evaluate the CRISPR/Cas systems for treating different genetic diseases and highlight promising preclinical research on CRISPR/Cas mediated treatment of a great diversity of genetic disorders. Ultimately, we discuss the future of CRISPR/Cas mediated genome editing in genetic diseases.

Orchestration of mesenchymal plasticity and immune evasiveness via rewiring of the metabolic program in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most fatal cancer in humans, due to its difficulty of early detection and its high metastatic ability. The occurrence of epithelial to mesenchymal transition in preinvasive pancreatic lesions has been implicated in the early dissemination, drug resistance, and cancer stemness of PDAC. PDAC cells also have a reprogrammed metabolism, regulated by driver mutation-mediated pathways, a desmoplastic tumor microenvironment (TME), and interactions with stromal cells, including pancreatic stellate cells, fibroblasts, endothelial cells, and immune cells. Such metabolic reprogramming and its functional metabolites lead to enhanced mesenchymal plasticity, and creates an acidic and immunosuppressive TME, resulting in the augmentation of protumor immunity via cancer-associated inflammation. In this review, we summarize our recent understanding of how PDAC cells acquire and augment mesenchymal features via metabolic and immunological changes during tumor progression, and how mesenchymal malignancies induce metabolic network rewiring and facilitate an immune evasive TME. In addition, we also present our recent findings on the interesting relevance of the small G protein ADP-ribosylation factor 6-based signaling pathway driven by KRAS/TP53 mutations, inflammatory amplification signals mediated by the proinflammatory cytokine interleukin 6 and RNA-binding protein ARID5A on PDAC metabolic reprogramming and immune evasion, and finally discuss potential therapeutic strategies for the quasi-mesenchymal subtype of PDAC.

MicroRNA-874 targets phosphomevalonate kinase and inhibits cancer cell growth via the mevalonate pathway

The microRNA (miR) miR-874, a potential tumour suppressor, causes cell death via target gene suppression in various cancer types. Mevalonate pathway inhibition also causes cell death in breast cancer. However, the relationship between the mevalonate pathway and miR-874-induced apoptosis or its association with the tumour suppressor p53 has not been elucidated. We identified phosphomevalonate kinase (PMVK), a key mevalonate pathway enzyme, and sterol regulatory element-binding factor 2 (SREBF2), the master cholesterol biosynthesis regulator, as direct miR‑874 targets. Next-generation sequencing analysis revealed a significant miR-874-mediated downregulation of PMVK and SREBF2 gene expression and p53 pathway enrichment. Luciferase reporter assays showed that miR-874 directly regulated PMVK and SREBF2. miR-874-induced apoptosis was p53 dependent, and single-cell RNA sequencing analysis demonstrated that miR-874 transfection resulted in apoptosis and p53 pathway activation. Downregulation of PMVK expression also caused cell cycle arrest and p53 pathway activation, which was rescued by geranylgeranyl pyrophosphate (GGPP) supplementation. Analysis of The Cancer Genome Atlas (TCGA) database indicated a negative correlation between miR-874 and PMVK expression and between miR-874 and SREBF2 expression. These findings suggest that miR-874 suppresses the mevalonate pathway by targeting SREBF2 and PMVK, resulting in GGPP depletion, which activates the p53 pathway and promotes cycle arrest or apoptosis.

Structural insights into the substrate binding of phosphomevalonate kinase from the silkworm, Bombyx mori

Phosphomevalonate kinase (PMK) is an important enzyme involved in the juvenile hormone (JH) biosynthesis pathway that catalyzes the phosphorylation of mevalonate 5-phosphate into mevalonate 5-diphosphate in the mevalonate pathway. Herein, we report the crystal structure of insect PMK from Bombyx mori (BmPMK) at a resolution of 1.60 Å. The overall structure of BmPMK adopts a compact α/β conformation with two parts: the core and lid regions. The interface between the core and lid regions forms a continuous and negatively charged groove to accommodate the substrates. Using computational simulation combined with site-directed mutagenesis and biochemical analysis, we define the binding mode of BmPMK with the cofactor and the substrate, which provides a structural basis for understanding the catalytic mechanism and the design of inhibitors of PMK. Moreover, BmPMK showed the optimal enzyme activity at pH 8.0, and the optimal temperature was 30 °C, using mevalonate 5-phosphate as the substrate. The expression profiles and kinetic analyses of BmPMK indicated that it plays critical role in the control of JH biosynthesis in silkworms. Collectively, these findings provide a better understanding of the structural and biochemical features of insect PMK.

Use of Cinnamon and its Derivatives in Poultry Nutrition

The recent trend toward banning the use of antibiotics in poultry feed as a growth promoter directs the scientific community to look for natural alternatives with potential growth-promoting and immunomodulating properties. Phytogenic feed additives have attracted significant attention as alternatives to antibiotics to improve growth performance and enhance immune responses. They have anti-inflammatory, antioxidant, antiviral, and antifungal properties, depending on their chemical structure and composition. Scientists are using these non-conventional ingredients as feed additives in the form of oil or powder. Essential oils (EO) are volatile liquids produced from aromatic plants. Their application has gained momentum in controlling cholesterol as free radical scavengers, anti-microbials, antifungals, and stimulants of digestive enzymes. EO's possible antimicrobial features against harmful pathogens are primarily associated with the high content of volatile components in oils. The current chapter highlights the beneficial impact of cinnamon oil as a feed additive on poultry growth performance, meat quality, carcass traits, and its hypo-cholesterolaemic impact, antioxidant act, microbiological aspects, and immunomodulatory effects.

Deciphering the mechanism of anhydrobiosis in the entomopathogenic nematode Heterorhabditis indica through comparative transcriptomics

The entomopathogenic nematode, Heterorhabditis indica, is a popular biocontrol agent of high commercial significance. It possesses tremendous genetic architecture to survive desiccation stress by undergoing anhydrobiosis to increase its lifespan-an attribute exploited in the formulation technology. The comparative transcriptome of unstressed and anhydrobiotic H. indica revealed several previously concealed metabolic events crucial for adapting towards the moisture stress. During the induction of anhydrobiosis in the infective juveniles (IJ), 1584 transcripts were upregulated and 340 downregulated. As a strategy towards anhydrobiotic survival, the IJ showed activation of several genes critical to antioxidant defense, detoxification pathways, signal transduction, unfolded protein response and molecular chaperones and ubiquitin-proteasome system. Differential expression of several genes involved in gluconeogenesis - β-oxidation of fatty acids, glyoxylate pathway; glyceroneogenesis; fatty acid biosynthesis; amino-acid metabolism - shikimate pathway, sachharopine pathway, kyneurine pathway, lysine biosynthesis; one-carbon metabolism-polyamine pathway, transsulfuration pathway, folate cycle, methionine cycle, nucleotide biosynthesis; mevalonate pathway; and glyceraldehyde-3-phosphate dehydrogenase were also observed. We report the role of shikimate pathway, sachharopine pathway and glyceroneogenesis in anhydrobiotes, and seven classes of repeat proteins, specifically in H. indica for the first time. These results provide insights into anhydrobiotic survival strategies which can be utilized to strengthen the development of novel formulations with enhanced and sustained shelf-life.

Anti-SRP immune-mediated necrotizing myopathy: A critical review of current concepts

Purpose of review

This review aims to describe clinical and histological features, treatment, and prognosis in patients with anti-signal recognition particle (SRP) autoantibodies positive immune-mediated necrotizing myopathy (SRP-IMNM) based on previous findings.

Previous findings

Anti-SRP autoantibodies are specific in IMNM. Humoral autoimmune and inflammatory responses are the main autoimmune characteristics of SRP-IMNM. SRP-IMNM is clinically characterized by acute or subacute, moderately severe, symmetrical proximal weakness. Younger patients with SRP-IMNM tend to have more severe clinical symptoms. Patients with SRP-IMNM may be vulnerable to cardiac involvement, which ought to be regularly monitored and cardiac magnetic resonance imaging is the recommended detection method. The pathological features of SRP-IMNM are patchy or diffuse myonecrosis and myoregeneration accompanied by a paucity of inflammatory infiltrates. Endoplasmic reticulum stress-induced autophagy pathway and necroptosis are activated in skeletal muscle of SRP-IMNM. Treatment of refractory SRP-IMNM encounters resistance and warrants further investigation.

Summary

Anti-SRP autoantibodies define a unique population of IMNM patients. The immune and non-immune pathophysiological mechanisms are involved in SRP-IMNM.

Role of STAR and SCP2/SCPx in the Transport of Cholesterol and Other Lipids

Cholesterol is a lipid molecule essential for several key cellular processes including steroidogenesis. As such, the trafficking and distribution of cholesterol is tightly regulated by various pathways that include vesicular and non-vesicular mechanisms. One non-vesicular mechanism is the binding of cholesterol to cholesterol transport proteins, which facilitate the movement of cholesterol between cellular membranes. Classic examples of cholesterol transport proteins are the steroidogenic acute regulatory protein (STAR; STARD1), which facilitates cholesterol transport for acute steroidogenesis in mitochondria, and sterol carrier protein 2/sterol carrier protein-x (SCP2/SCPx), which are non-specific lipid transfer proteins involved in the transport and metabolism of many lipids including cholesterol between several cellular compartments. This review discusses the roles of STAR and SCP2/SCPx in cholesterol transport as model cholesterol transport proteins, as well as more recent findings that support the role of these proteins in the transport and/or metabolism of other lipids.

Increased core body temperature exacerbates defective protein prenylation in mouse models of mevalonate kinase deficiency

Mevalonate kinase deficiency (MKD) is characterized by recurrent fevers and flares of systemic inflammation, caused by biallelic loss-of-function mutations in MVK. The underlying disease mechanisms and triggers of inflammatory flares are poorly understood because of the lack of in vivo models. We describe genetically modified mice bearing the hypomorphic mutation p.Val377Ile (the commonest variant in patients with MKD) and amorphic, frameshift mutations in Mvk. Compound heterozygous mice recapitulated the characteristic biochemical phenotype of MKD, with increased plasma mevalonic acid and clear buildup of unprenylated GTPases in PBMCs, splenocytes, and bone marrow. The inflammatory response to LPS was enhanced in compound heterozygous mice and treatment with the NLRP3 inflammasome inhibitor MCC950 prevented the elevation of circulating IL-1β, thus identifying a potential inflammasome target for future therapeutic approaches. Furthermore, lines of mice with a range of deficiencies in mevalonate kinase and abnormal prenylation mirrored the genotype-phenotype relationship in human MKD. Importantly, these mice allowed the determination of a threshold level of residual enzyme activity, below which protein prenylation is impaired. Elevated temperature dramatically but reversibly exacerbated the deficit in the mevalonate pathway and the defective prenylation in vitro and in vivo, highlighting increased body temperature as a likely trigger of inflammatory flares.

Di(2-ethylhexyl) phthalate disturbs cholesterol metabolism through oxidative stress in rat liver

Di(2-ethylhexyl) phthalate (DEHP) is widely used and has been implicated in hepatotoxicity, although the mechanism is unclear. Here, we investigated the effect of DEHP on hepatic cholesterol metabolism in SD rats exposed to 0 and 300 mg/kg/day DEHP for 12 weeks. An RNA-Seq analysis was performed to describe the hepatic responses to long-term DEHP exposure in combination with serological and oxidative stress parameter measurements. DEHP increased the serum levels of total cholesterol (TC), high-density lipoprotein (HDL), and alanine transaminase (ALT). Moreover, DEHP increased the content of malondialdehyde (MDA) and decreased antioxidant enzyme activities in the liver. Transcriptomic results revealed that DEHP dramatically changed the cholesterol metabolism pathway and oxidation-reduction process and depressed gene expression involved in cholesterol efflux and monooxygenase activity. Total antioxidant capacity (T-AOC) positively correlated with Abcg5 and Abcg8. Overall, this study showed the mechanisms underlying hepatotoxicity caused by DEHP, providing new insights into understanding DEHP poisoning.

High fat diet-induced hyperlipidemia and tissue steatosis in rabbits through modulating ileal microbiota

High-fat diet (HFD) and overnutrition are important starting factors that may alter intestinal microbiota, lipid metabolism, and systemic inflammation. However, there were few studies on how intestinal microbiota contributes to tissue steatosis and hyperlipidemia. Here, we investigated the effect of lipid metabolism disorder-induced inflammation via toll-like receptor 2 (TLR-2), toll-like receptor 4 (TLR-4), and nuclear factor-κB (NF-κB) pathways at the intestinal level in response to HFD. Twenty 80-day-old male New Zealand White rabbits were randomly divided into the normal diet group (NDG) and the high-fat diet group (HDG) for 80 days. Growth performance, blood biochemical parameters, lipid metabolism, inflammation, degree of tissue steatosis, and intestinal microbial composition were measured. HFD increased the relative abundance of Christensenellaceae_R_7_group, Marvinbryantia, Akkermansia etc., with a reduced relative abundance of Enterorhabdus and Lactobacillus. Moreover, HFD caused steatosis in the liver and abdominal fat and abnormal expression of some genes related to lipid metabolism and tight junction proteins. The TLR-2, TLR-4, NF-κB, TNF-α, and IL-6 were confirmed by overexpression with downregulation of IL-10. Serum biochemical indices (TG, TCHO, LDL-C, and HDL-C) were also increased, indicating evidence for the development of the hyperlipidemia model. Correlation analysis showed that this microbial dysbiosis was correlated with lipid metabolism and inflammation, which were associated with the intestinal tract's barrier function and hyperlipidemia. These results provide an insight into the relationship between HFD, the intestinal microbiota, intestinal barrier, tissue inflammation, lipid metabolism, and hyperlipidemia. KEY POINTS: • High-fat diet leads to ileal microbiota disorders • Ileal microbiota mediates local and systemic lipid metabolism disorders and inflammation • There is a specific link between ileal microbiota, histopathology, and hyperlipidemia.

A fungal tolerance trait and selective inhibitors proffer HMG-CoA reductase as a herbicide mode-of-action

Decades of intense herbicide use has led to resistance in weeds. Without innovative weed management practices and new herbicidal modes of action, the unabated rise of herbicide resistance will undoubtedly place further stress upon food security. HMGR (3-hydroxy-3-methylglutaryl-coenzyme A reductase) is the rate limiting enzyme of the eukaryotic mevalonate pathway successfully targeted by statins to treat hypercholesterolemia in humans. As HMGR inhibitors have been shown to be herbicidal, HMGR could represent a mode of action target for the development of herbicides. Here, we present the crystal structure of a HMGR from Arabidopsis thaliana (AtHMG1) which exhibits a wider active site than previously determined structures from different species. This plant conserved feature enables the rational design of specific HMGR inhibitors and we develop a tolerance trait through sequence analysis of fungal gene clusters. These results suggest HMGR to be a viable herbicide target modifiable to provide a tolerance trait.

Modulation of radiosensitivity of DU145 prostate carcinoma cells by simvastatin

PURPOSE

To investigate antiproliferative effects of simvastatin in combination with ionizing radiation on DU145 prostate cancer cells and its influence on cellular HMG-CoA-reductase levels.

METHODS

Proliferative responses of DU145 cells were estimated by means of a clonogenic assay or the crystal violet procedure. HMG-CoA-reductase levels were measured by western blot analysis.

RESULTS

The antiproliferative effects of simvastatin and radiation are dependent on simvastatin dose, radiation dose and treatment time. In vitro treatment of DU145 cells with simvastatin induced HMG-CoA-reductase levels.

CONCLUSION

Ionizing radiation more profoundly reduces proliferation as compared to simvastatin exposure, while the combined application of both modalities is synergistic. The inhibition of CoA-reductase may contribute to these effects.

Biochemistry and Nanomechanical Properties of Human Colon Cells upon Simvastatin, Lovastatin, and Mevastatin Supplementations: Raman Imaging and AFM Studies

One of the most important areas of medical science is oncology, which is responsible for both the diagnostics and treatment of cancer diseases. Over the years, there has been an intensive development of cancer diagnostics and treatment. This paper shows the comparison of normal (CCD-18Co) and cancerous (CaCo-2) cell lines of the human gastrointestinal tract on the basis of nanomechanical and biochemical properties to obtain information on cancer biomarkers useful in oncological diagnostics. The research techniques used were Raman spectroscopy and imaging and atomic force microscopy (AFM). In addition, the studies also included the effect of the statin compounds—mevastatin, lovastatin, and simvastatin—and their influence on biochemical and nanomechanical changes of cell properties using Raman imaging and AFM techniques. The cytotoxicity of statins was determined using XTT tests.

Selenium-Enriched Cardamine violifolia Increases Selenium and Decreases Cholesterol Concentrations in Liver and Pectoral Muscle of Broilers

BACKGROUND

Supernutrition of selenium (Se) in an effort to produce Se-enriched meat may inadvertently cause lipid accumulation. Se-enriched Cardamine violifolia (SeCv) contains >80% of Se in organic forms.

OBJECTIVES

This study was to determine whether feeding chickens a high dose of SeCv could produce Se-biofortified muscle without altering their lipid metabolism.

METHODS

Day-old male broilers were allocated to 4 groups (6 cages/group and 6 chicks/cage) and were fed either a corn-soy base diet (BD, 0.13-0.15 mg Se/kg), the BD plus 0.5 mg Se/kg as sodium selenite (SeNa) or as SeCv, or the BD plus a low-Se Cardamine violifolia (Cv, 0.20-0.21mg Se/kg). At week 6, concentrations of Se and lipid and expression of selenoprotein and lipid metabolism-related genes were determined in the pectoral muscle and liver.

RESULTS

The 4 diets showed no effects on growth performance of broilers. Compared with the other 3 diets, SeCv elevated (P < 0.05) Se concentrations in the pectoral muscle and liver by 14.4-127% and decreased (P < 0.05) total cholesterol concentrations by 12.5-46.7% and/or triglyceride concentrations by 28.8-31.1% in the pectoral muscle and/or liver, respectively. Meanwhile, SeCv enhanced (P < 0.05) muscular α-linolenic acid (80.0%) and hepatic arachidonic acid (58.3%) concentrations compared with SeNa and BD, respectively. SeCv downregulated (P < 0.05) the cholesterol and triglyceride synthesis-related proteins (sterol regulatory element binding transcription factor 2 and diacylglycerol O-acyltransferase 2) and upregulated (P < 0.05) hydrolysis and β-oxidation of fatty acid-related proteins (lipoprotein lipase, fatty acid binding protein 1, and carnitine palmitoyltransferase 1A), as well as selenoprotein P1 and thioredoxin reductase activity in the pectoral muscle and/or liver compared with SeNa.

CONCLUSIONS

Compared with SeNa, SeCv effectively raised Se and reduced lipids in the liver and muscle of broilers. The effect was mediated through the regulation of the cholesterol and triglyceride biosynthesis and utilization-related genes.

Serum cholesterol loading capacity on macrophages is linked to coronary atherosclerosis and cardiovascular event risk in rheumatoid arthritis

Objectives

Cholesterol loading capacity (CLC) describes the ability of serum to deliver cholesterol to cells. It is linked to foam cell formation, a pivotal step in atherosclerotic plaque development. We evaluate the associations of CLC with coronary atherosclerosis presence, burden and cardiovascular risk in patients with rheumatoid arthritis (RA).

Methods

Coronary atherosclerosis (any, high-risk low-attenuation plaque and obstructive plaque) was evaluated with CT angiography in 141 patients. Participants were prospectively followed for 6.0±2.4 years and cardiovascular events including cardiac death, myocardial infarction, unstable angina, stroke, claudication, revascularisation and hospitalised heart failure were recorded. CLC was quantified as intracellular cholesterol in human macrophages after incubation with patient serum.

Results

CLC was not linked to overall plaque presence or burden after adjustments for atherosclerotic cardiovascular disease (ASCVD) score, statin use and low-density lipoprotein cholesterol. However, CLC associated with presence and numbers of any, low-attenuation and obstructive plaques exclusively in biologic disease-modifying antirheumatic drugs (bDMARD) non-users (p for interaction ≤0.018). CLC associated with cardiovascular event risk overall after adjustments for ASCVD and number of segments with plaque (HR=1.76 (95% CI 1.16 to 2.67) per 1 SD increase in CLC, p=0.008). Additionally, bDMARD use modified the impact of CLC on event risk; CLC associated with events in bDMARD non-users (HR=2.52 (95% CI 1.36 to 4.65) per 1SD increase in CLC, p=0.003) but not users.

Conclusion

CLC was linked to long-term cardiovascular event risk in RA and associated with high-risk low attenuation and obstructive coronary plaque presence and burden in bDMARD non-users. Its prospective validation as a predictive biomarker may be, therefore, warranted.

Mitotane Targets Lipid Droplets to Induce Lipolysis in Adrenocortical Carcinoma

INTRODUCTION

Adrenocortical carcinoma (ACC) is a rare aggressive cancer with low overall survival. Adjuvant mitotane improves survival but is limited by poor response rates and resistance. Mitotane's efficacy is attributed to the accumulation of toxic free cholesterol, predominantly through cholesterol storage inhibition. However, targeting this pathway has proven unsuccessful. We hypothesize that mitotane-induced free-cholesterol accumulation is also mediated through enhanced breakdown of lipid droplets.

METHODOLOGY

ATCC-H295R (mitotane-sensitive) and MUC-1 (mitotane-resistant) ACC cells were evaluated for lipid content using specific BODIPY dyes. Protein expression was evaluated by immunoblotting and flow cytometry. Cell viability was measured by quantifying propidium iodide-positive cells following mitotane treatment and pharmacological inhibitors of lipolysis.

RESULTS

H295R and MUC-1 cells demonstrated similar neutral lipid droplet numbers at baseline. However, evaluation of lipid machinery demonstrated distinct profiles in each model. Analysis of intracellular lipid droplet content showed H295R cells preferentially store cholesteryl esters, whereas MUC-1 cells store triacylglycerol. Decreased lipid droplets were associated with increased lipolysis in H295R and in MUC-1 at toxic mitotane concentrations. Pharmacological inhibition of lipolysis attenuated mitotane-induced toxicity in both models.

CONCLUSION

We highlight that lipid droplet breakdown and activation of lipolysis represent a putative additional mechanism for mitotane-induced cytotoxicity in ACC. Further understanding of cholesterol and lipids in ACC offers potential novel therapeutic exploitation, especially in mitotane-resistant disease.

Cholesterol Paradigm and Beyond in Atherosclerotic Cardiovascular Disease: Cholesterol, Sterol Regulatory Element-Binding Protein, Inflammation, and Vascular Cell Mobilization in Vasculopathy

Hypercholesterolemia is a well-established risk factor for atherosclerotic cardiovascular disease (ASCVD). How cholesterol and its carrier lipoproteins are involved in ASCVD is still under extensive investigation. Satins are thus far the best-proven class of cholesterol-lowering medications to improve the clinical outcomes of ASCVD. Statins specifically inhibit the rate-limiting enzyme 3-hydroxy-3-methylglutaryl-CoA reductase of the mevalonate pathway for cholesterol biosynthesis. The widely accepted theory is that statins inhibit the hepatic cholesterol synthesis causing upregulation of hepatocyte low-density lipoprotein (LDL) receptor; receptor-mediated LDL uptake and metabolism in the liver results in reduction of circulating LDL cholesterol, which subsequently reduces vascular deposition and retention of cholesterol or LDL in atherogenesis. Nevertheless, cholesterol biosynthesis is ubiquitous, also in extrahepatic cells including those in vascular wall, under tight regulation by sterol regulatory element-binding protein (SREBP), the master gene transcription factor governing cholesterol biosynthesis. Studies have shown that SREBP can be upregulated in vascular wall subject to injury or stent implantation. SREBP can be activated by proinflammatory and mitogenic factors in vascular cells, leading to hyperactive mevalonate pathway, which promotes vascular cell mobilization, further proinflammatory and mitogenic factor release from vascular cells, and vascular inflammation. In this article, we review the cellular cholesterol homeostasis regulation by SREBP and SREBP-mediated vascular hyperactive cholesterol biosynthesis, we term vascular hypercholesterolism, in the pathogenesis of ASCVD and vasculopathy. SREBP functions as a platform bridging cholesterol, inflammation, and vascular cell mobilization in ASCVD pathogenesis. Targeting vascular hypercholesterolism could open a new avenue in fighting against ASCVD.

The HDL particle composition determines its antitumor activity in pancreatic cancer

Despite enormous efforts to improve therapeutic options, pancreatic cancer remains a fatal disease and is expected to become the second leading cause of cancer-related deaths in the next decade. Previous research identified lipid metabolic pathways to be highly enriched in pancreatic ductal adenocarcinoma (PDAC) cells. Thereby, cholesterol uptake and synthesis promotes growth advantage to and chemotherapy resistance for PDAC tumor cells. Here, we demonstrate that high-density lipoprotein (HDL)-mediated efficient cholesterol removal from cancer cells results in PDAC cell growth reduction and induction of apoptosis in vitro. This effect is driven by an HDL particle composition-dependent interaction with SR-B1 and ABCA1 on cancer cells. AAV-mediated overexpression of APOA1 and rHDL injections decreased PDAC tumor development in vivo. Interestingly, plasma samples from pancreatic-cancer patients displayed a significantly reduced APOA1-to-SAA1 ratio and a reduced cholesterol efflux capacity compared with healthy donors. We conclude that efficient, HDL-mediated cholesterol depletion represents an interesting strategy to interfere with the aggressive growth characteristics of PDAC.

Antagonism of miR-148a attenuates atherosclerosis progression in APOBTGApobec-/-Ldlr+/- mice: A brief report

OBJECTIVE

miR-148a-3p (miR-148a) is a hepatic and immune-enriched microRNA (miRNA) that regulates macrophage-related lipoprotein metabolism, cholesterol homeostasis, and inflammation. The contribution of miR-148a-3p to the progression of atherosclerosis is unknown. In this study, we determined whether miR-148a silencing mitigated atherogenesis in APOBTGApobec-/-Ldlr+/- mice.

METHODS

APOBTGApobec-/-Ldlr+/- mice were fed a typical Western-style diet for 22 weeks and injected with a nontargeting locked nucleic acid (LNA; LNA control) or miR-148a LNA (LNA 148a) for the last 10 weeks. At the end of the treatment, the mice were sacrificed, and circulating lipids, hepatic gene expression, and atherosclerotic lesions were analyzed.

RESULTS

Examination of atherosclerotic lesions revealed a significant reduction in plaque size, with marked remodeling of the lesions toward a more stable phenotype. Mechanistically, miR-148a levels influenced macrophage cholesterol efflux and the inflammatory response. Suppression of miR-148a in murine primary macrophages decreased mRNA levels of proinflammatory M1-like markers (Nos2, Il6, Cox2, and Tnf) and increased the expression of anti-inflammatory genes (Arg1, Retlna, and Mrc1).

CONCLUSIONS

Therapeutic silencing of miR148a mitigated the progression of atherosclerosis and promoted plaque stability. The antiatherogenic effect of miR-148a antisense therapy is likely mediated by the anti-inflammatory effects observed in macrophages treated with miR-148 LNA and independent of significant changes in circulating low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C).

MYCN and Metabolic Reprogramming in Neuroblastoma

Neuroblastoma is a pediatric cancer responsible for approximately 15% of all childhood cancer deaths. Aberrant MYCN activation, as a result of genomic MYCN amplification, is a major driver of high-risk neuroblastoma, which has an overall survival rate of less than 50%, despite the best treatments currently available. Metabolic reprogramming is an integral part of the growth-promoting program driven by MYCN, which fuels cell growth and proliferation by increasing the uptake and catabolism of nutrients, biosynthesis of macromolecules, and production of energy. This reprogramming process also generates metabolic vulnerabilities that can be exploited for therapy. In this review, we present our current understanding of metabolic reprogramming in neuroblastoma, focusing on transcriptional regulation as a key mechanism in driving the reprogramming process. We also highlight some important areas that need to be explored for the successful development of metabolism-based therapy against high-risk neuroblastoma.

Combining Isoprenoid Probes with Antibody Markers for Mass Cytometric Analysis of Prenylation in Single Cells

Protein prenylation is an essential post-translational modification that plays a key role in facilitating protein localization. Aberrations in protein prenylation have been indicated in multiple disease pathologies including progeria, some forms of cancer, and Alzheimer's disease. While there are single-cell methods to study prenylation, these methods cannot simultaneously assess prenylation and other cellular changes in the complex cell environment. Here, we report a novel method to monitor, at the single-cell level, prenylation and expression of autophagy markers. An isoprenoid analogue containing a terminal alkyne, substrate of prenylation enzymes, was metabolically incorporated into cells in culture. Treatment with a terbium reporter containing an azide functional group, followed by copper-catalyzed azide-alkyne cycloaddition, covalently attached terbium ions to prenylated proteins within cells. In addition, simultaneous treatment with a holmium-containing analogue of the reporter, without an azide functional group, was used to correct for non-specific retention at the single-cell level. This procedure was compatible with other mass cytometric sample preparation steps that use metal-tagged antibodies. We demonstrate that this method reports changes in levels of prenylation in competitive and inhibitor assays, while tracking autophagy molecular markers with metal-tagged antibodies. The method reported here makes it possible to track prenylation along with other molecular pathways in single cells of complex systems, which is essential to elucidate the role of this post-translational modification in disease, cell response to pharmacological treatments, and aging.

Identification and Evolution Analysis of the Complete Methyl Farnesoate Biosynthesis and Related Pathway Genes in the Mud Crab, Scylla paramamosain

The sesquiterpenoid hormone methyl farnesoate (MF) plays a vital role during crustacean development, which is mainly evidenced by its varied titers during different developmental stages. However, the biosynthesis pathways of MF remain obscure to some extent. In this study, we identified the complete MF biosynthesis and related pathway genes in Scylla paramamosain, including three involved in acetyl-CoA metabolism, eight in the mevalonate pathway, five in the sesquiterpenoids synthesis pathway, and five in the methionine cycle pathway. Bioinformatics, genomic structure, and phylogenetic analysis indicated that the JH biosynthesis genes might have experienced evolution after species differentiation. The mRNA tissue distribution analysis revealed that almost all genes involving in or relating to MF syntheses were highly expressed in the mandibular organ (MO), among which juvenile hormone acid methyltransferase was exclusively expressed in the MO, suggesting that most of these genes might mainly function in MF biosynthesis and that the methionine cycle pathway genes might play a crucial regulatory role during MF synthesis. In addition, the phylogenetic and tissue distribution analysis of the cytochrome P450 CYP15-like gene suggested that the epoxidized JHs might exist in crustaceans, but are mainly synthesized in hepatopancreas rather than the MO. Finally, we also found that betaine-homocysteine S-methyltransferase genes were lost in insects while methionine synthase was probably lost in most insects except Folsomia candida, indicating a regulatory discrepancy in the methionine cycle between crustaceans and insects. This study might increase our understanding of synthetic metabolism tailored for sesquiterpenoid hormones in S. paramamosain and other closely related species.

Farnesyl diphosphate synthase regulated endothelial proliferation and autophagy during rat pulmonary arterial hypertension induced by monocrotaline

Background

The proliferation ability and autophagy level of pulmonary artery endothelial cells (PAECs) play an important role in promoting the development of pulmonary artery hypertension (PAH), and there is still no effective treatment for PAH. Farnesyl diphosphate synthase (FDPS) is a key enzyme in the mevalonate pathway. The intermediate metabolites of this pathway are closely related to the activity of autophagy-associated small G proteins, including Ras-related C3 botulinum toxin substrate 1 (Rac1). Studies have shown that the mevalonate pathway affects the activation levels of different small G proteins, autophagy signaling pathways, vascular endothelial function, and so on. However, the exact relationship between them is still unclear in PAH.

Method

In vitro, western blotting and mRFP-GFP-LC3 puncta formation assays were used to observe the expression of FDPS and the level of autophagy in PAECs treated with monocrotaline pyrrole (MCTP). In addition, cell proliferation and migration assays were used to assess the effect of FDPS on endothelial function, and Rac1 activity assays were used to evaluate the effect of Rac1 activation on PAEC autophagy via the PI3K/AKT/mTOR signaling pathway. In vivo, the right heart catheterization method, hematoxylin and eosin (H&E) staining and western blotting were used to determine the effect of FDPS on PAEC autophagy and monocrotaline (MCT)-induced PAH.

Results

We show that the expression of FDPS is increased in the PAH module in vitro and in vivo, concomitant with the induction of autophagy and the activation of Rac1. Our data demonstrate that inhibition of FDPS ameliorates endothelial function and decreases MCT-induced autophagy levels. Mechanistically, we found that FDPS promotes autophagy, Rac1 activity and endothelial disfunction through the PI3K/AKT/mTOR signaling pathway.

Conclusion

Our study suggests that FDPS contributes to active small G protein-induced autophagy during MCT-induced PAH, which may serve as a potential therapeutic target against PAH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00511-7.

Regulation of cholesterol homeostasis in health and diseases: from mechanisms to targeted therapeutics

Disturbed cholesterol homeostasis plays critical roles in the development of multiple diseases, such as cardiovascular diseases (CVD), neurodegenerative diseases and cancers, particularly the CVD in which the accumulation of lipids (mainly the cholesteryl esters) within macrophage/foam cells underneath the endothelial layer drives the formation of atherosclerotic lesions eventually. More and more studies have shown that lowering cholesterol level, especially low-density lipoprotein cholesterol level, protects cardiovascular system and prevents cardiovascular events effectively. Maintaining cholesterol homeostasis is determined by cholesterol biosynthesis, uptake, efflux, transport, storage, utilization, and/or excretion. All the processes should be precisely controlled by the multiple regulatory pathways. Based on the regulation of cholesterol homeostasis, many interventions have been developed to lower cholesterol by inhibiting cholesterol biosynthesis and uptake or enhancing cholesterol utilization and excretion. Herein, we summarize the historical review and research events, the current understandings of the molecular pathways playing key roles in regulating cholesterol homeostasis, and the cholesterol-lowering interventions in clinics or in preclinical studies as well as new cholesterol-lowering targets and their clinical advances. More importantly, we review and discuss the benefits of those interventions for the treatment of multiple diseases including atherosclerotic cardiovascular diseases, obesity, diabetes, nonalcoholic fatty liver disease, cancer, neurodegenerative diseases, osteoporosis and virus infection.

Enhancement of Squalene Production by Constitutive Expression of the 3-Hydroxy-3-Methylglutaryl-CoA Reductase in Aurantiochytrium sp. 18W-13a

Squalene has a wide range of applications in the industry sectors of dietary supplements, cosmetics, immunization, and pharmaceuticals. Yet, suitable organisms as the source of squalene are limited. It is reported that the thraustochytrid Aurantiochytrium sp. strain 18W-13a can accumulate high content of squalene. However, squalene production in this organism is fluctuated under various conditions and is not yet optimized for commercialization. In this organism, the mevalonate pathway supplies isopentenyl pyrophosphate, the initial substrate for squalene production. In this pathway, 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) is the rate-limiting enzyme. We found that the HMGR activity had a strong positive correlation with the squalene contents in the strain. We constitutively expressed the HMGR in this organism and found that the transformant showed increased and stable production of squalene as well as carotenoids and biomass. These results clearly indicated that the HMGR expression is the bottleneck of squalene synthesis in Aurantiochytrium sp.

Prenylation Defects and Oxidative Stress Trigger the Main Consequences of Neuroinflammation Linked to Mevalonate Pathway Deregulation

The cholesterol biosynthesis represents a crucial metabolic pathway for cellular homeostasis. The end products of this pathway are sterols, such as cholesterol, which are essential components of cell membranes, precursors of steroid hormones, bile acids, and other molecules such as ubiquinone. Furthermore, some intermediates of this metabolic system perform biological activity in specific cellular compartments, such as isoprenoid molecules that can modulate different signal proteins through the prenylation process. The defects of prenylation represent one of the main causes that promote the activation of inflammation. In particular, this mechanism, in association with oxidative stress, induces a dysfunction of the mitochondrial activity. The purpose of this review is to describe the pleiotropic role of prenylation in neuroinflammation and to highlight the consequence of the defects of prenylation.

Regulated degradation of HMG CoA reductase requires conformational changes in sterol-sensing domain

3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) is the rate-limiting enzyme in cholesterol synthesis and target of cholesterol-lowering statin drugs. Accumulation of sterols in endoplasmic reticulum (ER) membranes accelerates degradation of HMGCR, slowing the synthesis of cholesterol. Degradation of HMGCR is inhibited by its binding to UBIAD1 (UbiA prenyltransferase domain-containing protein-1). This inhibition contributes to statin-induced accumulation of HMGCR, which limits their cholesterol-lowering effects. Here, we report cryo-electron microscopy structures of the HMGCR-UBIAD1 complex, which is maintained by interactions between transmembrane helix (TM) 7 of HMGCR and TMs 2-4 of UBIAD1. Disrupting this interface by mutagenesis prevents complex formation, enhancing HMGCR degradation. TMs 2-6 of HMGCR contain a 170-amino acid sterol sensing domain (SSD), which exists in two conformations-one of which is essential for degradation. Thus, our data supports a model that rearrangement of the TMs in the SSD permits recruitment of proteins that initate HMGCR degradation, a key reaction in the regulatory system that governs cholesterol synthesis.

Comparing Transcriptomes Reveals Key Metabolic Mechanisms in Superior Growth Performance Nile Tilapia (Oreochromis niloticus)

Metabolic capacity is intrinsic to growth performance. To investigate superior growth performance in Nile tilapia, three full-sib families were bred and compared at the biochemical and transcriptome levels to determine metabolic mechanisms involved in significant growth differences between individuals under the same culture environment and feeding regime. Biochemical analysis showed that individuals in the higher growth group had significantly higher total protein, total triglyceride, total cholesterol, and high- and low-density lipoproteins, but significantly lower glucose, as compared with individuals in the lower growth group. Comparative transcriptome analysis showed 536 differentially expressed genes (DEGs) were upregulated, and 622 DEGs were downregulated. These genes were significantly enriched in three key pathways: the tricarboxylic acid cycle (TCA cycle), fatty acid biosynthesis and metabolism, and cholesterol biosynthesis and metabolism. Conjoint analysis of these key pathways and the biochemical parameters suggests that Nile tilapia with superior growth performance have higher ability to consume energy substrates (e.g., glucose), as well as higher ability to biosynthesize fatty acids and cholesterol. Additionally, the fatty acids biosynthesized by the superior growth performance individuals were less active in the catabolic pathway overall, but were more active in the anabolic pathway, and might be used for triglyceride biosynthesis to store excess energy in the form of fat. Furthermore, the tilapia with superior growth performance had lower ability to convert cholesterol into bile acids, but higher ability to convert it into sterols. We discuss the molecular mechanisms of the three key metabolic pathways, map the pathways, and note key factors that may impact the growth of Nile tilapia. The results provide an important guide for the artificial selection and quality enhancement of superior growth performance in tilapia.

New, Novel Lipid-Lowering Agents for Reducing Cardiovascular Risk: Beyond Statins

Statins are the cornerstone of the prevention and treatment of atherosclerotic cardiovascular disease (ASCVD). However, even under optimal statin therapy, a significant residual ASCVD risk remains. Therefore, there has been an unmet clinical need for novel lipid-lowering agents that can target low-density lipoprotein cholesterol (LDL-C) and other atherogenic particles. During the past decade, several drugs have been developed for the treatment of dyslipidemia. Inclisiran, a small interfering RNA that targets proprotein convertase subtilisin/kexin type 9 (PCSK9), shows comparable effects to that of PCSK9 monoclonal antibodies. Bempedoic acid, an ATP citrate lyase inhibitor, is a valuable treatment option for the patients with statin intolerance. Pemafibrate, the first selective peroxisome proliferator-activated receptor alpha modulator, showed a favorable benefit-risk balance in phase 2 trial, but the large clinical phase 3 trial (PROMINENT) was recently stopped for futility based on a late interim analysis. High dose icosapent ethyl, a modified eicosapentaenoic acid preparation, shows cardiovascular benefits. Evinacumab, an angiopoietin-like 3 (ANGPTL3) monoclonal antibody, reduces plasma LDL-C levels in patients with refractory hypercholesterolemia. Novel antisense oligonucleotides targeting apolipoprotein C3 (apoC3), ANGPTL3, and lipoprotein(a) have significantly attenuated the levels of their target molecules with beneficial effects on associated dyslipidemias. Apolipoprotein A1 (apoA1) is considered as a potential treatment to exploit the athero-protective effects of high-density lipoprotein cholesterol (HDL-C), but solid clinical evidence is necessary. In this review, we discuss the mode of action and clinical outcomes of these novel lipid-lowering agents beyond statins.

Statins Increase the Bioavailability of Fixed-Dose Combination of Sofosbuvir/Ledipasvir by Inhibition of P-glycoprotein

BACKGROUND

Coadministration of statins and direct acting antiviral agents is frequently used. This study explored the effects of both atorvastatin and lovastatin on pharmacokinetics of a fixed-dose combination of sofosbuvir/ledipasvir "FDCSL".

METHODS

12 healthy volunteers participated in a randomized, three-phase crossover trial and were administered a single atorvastatin dose 80 mg plus tablet containing 400/90 mg FDCSL, a single lovastatin dose 40 mg plus tablet containing 400/90 mg FDCSL, or tablets containing 400/90 mg FDCSL alone. Liquid chromatography-tandem mass spectrometry was used to analyze plasma samples of sofosbuvir, ledipasvir and sofosbuvir metabolite "GS-331007" and their pharmacokinetic parameters were determined.

RESULTS

Atorvastatin caused a significant rise in sofosbuvir bioavailability as explained by increasing in AUC0-∞ and Cmax by 34.36% and 11.97%, respectively. In addition, AUC0-∞ and Cmax of GS-331007 were increased by 73.73% and 67.86%, respectively after atorvastatin intake. Similarly, co-administration of lovastatin with FDCSL increased the bioavailability of sofosbuvir, its metabolite (AUC0-∞ increase by 17.2%, 17.38%, respectively, and Cmax increase by 12.03%, 22.24%, respectively). However, neither atorvastatin nor lovastatin showed a change in ledipasvir bioavailability. Hepatic elimination was not affected after statin intake with FDCSL. Compared to lovastatin, atorvastatin showed significant increase in AUC0-∞ and Cmax of both sofosbuvir and its metabolite.

CONCLUSIONS

Both atorvastatin and lovastatin increased AUC of sofosbuvir and its metabolite after concurrent administration with FDCSL. Statins' P-glycoprotein inhibition is the attributed mechanism of interaction. The increase in sofosbuvir bioavailability was more pronounced after atorvastatin intake. Close monitoring is needed after co-administration of atorvastatin and FDCSL.

Form of dietary selenium affects mRNA encoding cholesterol biosynthesis and immune response elements in the early luteal phase bovine corpus luteum

Widespread regions of the southeast United States have soils, and hence forages, deficient in selenium (Se), necessitating Se supplementation to grazing cattle for optimal immune function, growth, and fertility. We have reported that supplementation with an isomolar 1:1 mix (MIX) of inorganic (ISe) and organic (OSe) forms of Se increases early luteal phase (LP) progesterone (P4) above that in cows on ISe alone. Increased early LP P4 advances embryonic development. Our objective was to determine the effect of form of Se on the transcriptome of the early LP corpus luteum (CL) with the goal of elucidating form of Se-regulated processes affecting luteal steroidogenesis and function. Non-lactating, 3-yr-old Angus-cross cows underwent 45-d Se-depletion, then repletion periods, and then at least 90 d of supplementation (TRT) with 35 ppm Se/d as either ISe (n = 5) or MIX (n = 5). CL were then recovered on day 7 of the estrous cycle, total RNA isolated, and the effect of TRT on the luteal transcriptome evaluated using bovine gene 1.0 ST arrays (Affymetrix, Inc., Santa Clara, CA). The abundance of transcripts in each CL was subjected to one-way ANOVA using Partek Genomic Suite software to determine TRT effects. Microarray analysis indicated a total of 887 transcripts that were differentially expressed and functionally annotated, with 423 and 464 up- and down-regulated (P < 0.05) in MIX vs. ISe CL, respectively. Bioinformatic analysis (Ingenuity Pathway Analysis) revealed the top TRT-affected canonical pathways to include seven specific to cholesterol biosynthesis and two to inflammatory responses. Results from the microarray analysis were corroborated by targeted real-time PCR. MIX CL had increased (P < 0.05) abundance of transcripts regulating cholesterol biosynthesis including DHCR7, DHCR24, and CYP51A1 (fold changes of 1.65, 1.48, and 1.40, respectively), suggesting MIX-induced increases in P4 to be due, in part, to increased availability of substrate to luteal cells. In addition, MIX CL had increased (P < 0.05) abundance of immune-response transcripts including C1QC, FAS, ILR8B, and IL1R1 (fold changes of 2.30, 1.74, 1.66, and 1.63, respectively). SREBF1 mRNA was also increased (1.32-fold, P < 0.05) in the MIX CL, which increases cholesterol synthesis and stimulates IL1B, linking effects of form of supplemental Se (TRT) on cholesterol biosynthesis and immune function in the CL.

Cholesterol supports bovine granulosa cell inflammatory responses to lipopolysaccharide

During bacterial infections of the bovine uterus or mammary gland, ovarian granulosa cells mount inflammatory responses to lipopolysaccharide (LPS). In vitro, LPS stimulates granulosa cell secretion of the cytokines IL-1α and IL-1β, and the chemokine IL-8. These LPS-stimulated inflammatory responses depend on culturing granulosa cells with serum, but the mechanism is unclear. Here we tested the hypothesis that cholesterol supports inflammatory responses to LPS in bovine granulosa cells. We used granulosa cells isolated from 4-8 mm and > 8.5 mm diameter ovarian follicles and manipulated the availability of cholesterol. We found that serum or follicular fluid containing cholesterol increased LPS-stimulated secretion of IL-1α and IL-1β from granulosa cells. Conversely, depleting cholesterol using methyl-β-cyclodextrin diminished LPS-stimulated secretion of IL-1α, IL-1β and IL-8 from granulosa cells cultured in serum. Follicular fluid contained more high-density lipoprotein cholesterol than low-density lipoprotein cholesterol, and granulosa cells expressed the receptor for high-density lipoprotein, scavenger receptor class B member 1 (SCARB1). Furthermore, culturing granulosa cells with high-density lipoprotein cholesterol, but not low-density lipoprotein or very low-density lipoprotein cholesterol, increased LPS-stimulated inflammation in granulosa cells. Cholesterol biosynthesis also played a role in granulosa cell inflammation because RNA interference of mevalonate pathway enzymes inhibited LPS-stimulated inflammation. Finally, treatment with follicle-stimulating hormone, but not luteinizing hormone, increased LPS-stimulated granulosa cell inflammation, and follicle-stimulating hormone increased SCARB1 protein. However, changes in inflammation were not associated with changes in oestradiol or progesterone secretion. Taken together these findings imply that cholesterol supports inflammatory responses to LPS in granulosa cells.

Engineering Halomonas bluephagenesis via small regulatory RNAs

Halomonas bluephagenesis, a robust and contamination-resistant microorganism has been developed as a chassis for "Next Generation Industrial Biotechnology". The non-model H. bluephagenesis requires efficient tools to fine-tune its metabolic fluxes for enhanced production phenotypes. Here we report a highly efficient gene expression regulation system (PrrF1-2-HfqPa) in H. bluephagenesis, small regulatory RNA (sRNA) PrrF1 scaffold from Pseudomonas aeruginosa and a target-binding sequence that downregulate gene expression, and its cognate P. aeruginosa Hfq (HfqPa), recruited by the scaffold to facilitate the hybridization of sRNA and the target mRNA. The PrrF1-2-HfqPa system targeting prpC in H. bluephagenesis helps increase 3-hydroxyvalerate fraction in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) to 21 mol% compared to 3.1 mol% of the control. This sRNA system repressed phaP1 and minD simultaneously, resulting in large polyhydroxybutyrate granules. Further, an sRNA library targeting 30 genes was employed for large-scale target identification to increase mevalonate production. This work expands the study on using an sRNA system not based on Escherichia coli MicC/SgrS-Hfq to repress gene expression, providing a framework to exploit new powerful genome engineering tools based on other sRNAs.