The clinical potential of adipogenesis and obesity-related microRNAs.

Obesity is a growing health problem commonly associated with numerous metabolic disorders including type 2 diabetes, hypertension, cardiovascular disease, and some forms of cancer. The burden of obesity and associated cardiometabolic diseases are believed to arise through complex interplay between genetics and epigenetics predisposition, nutrition, environment, and lifestyle. However, the molecular basis and the repertoire of obesity-affecting factors are still unknown. Emerging evidence is connecting microRNAs (miRNAs) dysregulation with adipogenesis and obesity. Alteration in miRNAs expression could result in changes in the pattern of genes controlling a range of biological processes including inflammation, lipid metabolism, insulin resistance and adipogenesis. Hence, understanding exact roles of miRNAs as well as the degree of their contribution to the regulation of adipogenesis and fat cell development in obesity would provide new therapeutic targets for the development of novel and effective anti-obesity drugs. The objective of the current review is to: (i) discuss some of the latest development on relevant miRNAs dysregulation mainly in human adipogenesis and obesity, (ii) emphasize the role of circulating miRNAs as new promising therapeutics and attractive potential biomarkers for treating obesity and associated risk factor diseases, (iii) describe how dietary factors may influence obesity through modulation of miRNAs expression, (iv) highlight some of the actual limitations to the promise of miRNAs as novel therapeutics as well as to their translation for the benefit of patients, and finally (v) provide recommendations for future research on miRNA-based therapeutics that could lead to a breakthrough in the treatment of obesity and its associated pathologies.

Cardiovascular pharmacogenetics: a promise for genomically-guided therapy and personalized medicine.

Cardiovascular disease (CVD) is the leading cause of death worldwide. The basic causes of CVD are not fully understood yet. Substantial evidence suggests that genetic predisposition plays a vital role in the physiopathology of this complex disease. Hence, identification of genetic contributors to CVD will likely add diagnostic accuracy and better prediction of an individual's risk. With high-throughput genetics and genomics technology and newer genome-wide study approaches, a number of genetic variations across the human genome were uncovered. Evidence suggests that genetic defects could influence CVD development and inter-individual responses to widely used cardiovascular drugs like clopidogrel, aspirin, warfarin, and statins, and therefore, they may be integrated into clinical practice. If clinically validated, better understanding of these genetic variations may provide new opportunities for personalized diagnostic, pharmacogenetic-based drug selection and best treatment in personalized medicine. However, numerous gaps remain unsolved due to the lack of underlying pathological mechanisms for how genetic predisposition could contribute to CVD. This review provides an overview of the extraordinary scientific progress in our understanding of genetic and genomic basis of CVD as well as the development of relevant genetic biomarkers for this disease. Some of the actual limitations to the promise of these markers and their translation for the benefit of patients will be discussed.

Cytotoxic effects of four Caryophyllaceae species extracts on macrophage cell lines.

CONTEXT: Saponins have been reported to possess antitumor properties, to inhibit angiogenesis and to induce tumor apoptosis. OBJECTIVE: To test the possible cytotoxic effect of crude extracts from four Caryophyllaceae species including Gypsophila paniculata L., Gypsophila trichotoma Wend., Saponaria officinalis L., and Dianthus sylvestris Wulffen on cultured monocyte/macrophage cell lines. MATERIALS AND METHODS: After acid hydrolysis of the methanol-aqueous extracts, two representative prosaponins of the Caryophyllaceae, gypsogenin 3-O-glucuronide and quillaic acid 3-O-glucuronide were purified using solid-phase extraction (SPE), then identified by ultra-performance liquid chromatography-electrospray/mass spectrometry (UPLC-ESI/MS). Cytotoxic activity of the crude extracts at concentrations ranging from 0.1 to 200 µg/ml was evaluated on rat alveolar macrophage NR8383 and human monocytic THP-1 cell lines. Apoptosis was determined by measuring caspase-3 activity. RESULTS: Quantitative analysis by reversed-phase high-performance liquid chromatography (RP-HPLC) revealed a high content of gypsogenin 3-O-glucuronide in Gypsophila species roots (0.52-1.13% dry weight). At a concentration ≥10 µg/ml of crude extracts, a significant reduction of NR8383 and THP-1 cell lines viability was evidenced using the Trypan blue exclusion test. D. sylvestris extract exhibited the highest toxicity against THP-1 cells. Caspase-3 activation was evidenced after 4 and 24 h incubation of macrophages with 100 µg/ml of S. officinalis and G. trichotoma extracts, indicating apoptosis induction. DISCUSSION AND CONCLUSION: Crude extracts from the assayed species revealed cytotoxic effects toward macrophage cell lines. In Gypsophila species, gypsogenin 3-O-glucuronide derivatives could be responsible for the observed cytotoxicity. Therefore, crude extract of Caryophyllaceae is worth investigating for the potential development of agents against cancer cells.

Genomics and the prospects of existing and emerging therapeutics for cardiovascular diseases.

The growing knowledge about genetic influence on cardiovascular diseases (CVD) combined with the recently generated amounts of genomic data hold promise to the identification of new markers for atherosclerotic CVD. Cardiovascular pharmacogenomics and pharmacogenetics have now the potential for leading to identification of genetic contributors and therefore to the development of predictive genetic tests that could optimize drugs efficacy and minimize toxicity. Clinical studies have shown that genetic variations within cytochromes P450 (CYPs), 3-Hydroxyl-3-Methylglutaryl Coenzyme A Reductase (HMGCR) and apolipoprotein E (APOE) genes influence individual's response to lipid lowering statins. Furthermore, development of antagonists or inhibitors of molecules such as peroxisome proliferator-activated receptors (PPARs), lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), angiotensin-converting enzyme (ACE), angiotensin receptors and tumor necrosis factor (TNF)-alpha could be another alternative to prevent atherosclerosis. In addition, novel molecules under the name of biologics including family of peptides such as atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), urocortin, apelin and antimicrobial peptides (AMPs) could be considered as new targets for the prevention and treatment of CVD. In this article, we will focus mainly on recent genomic advances in the development of new markers and therapeutic agents for CVD. We present an array of molecules that could have pharmacological benefit for the treatment of heart disease. We also discuss in details new strategies including biologics, which are actually the focus of companies for clinical development of therapeutic drugs. All these efforts provide optimism and attractive promise to cure CVD.

Association of human cathelicidin (hCAP-18/LL-37) gene expression with cardiovascular disease risk factors.

BACKGROUND AND AIMS: Antimicrobial peptides (AMPs) are components of the innate immune system. In addition, evidence suggests that these peptides are associated with various inflammatory diseases. We examined whether expression of the cathelicidin LL-37 in peripheral blood mononuclear cells (PBMCs) is associated with cardiovascular risk factors. METHODS AND RESULTS: A total of 90 men and 87 women selected from STANISLAS cohort were studied. Expression of LL-37 mRNA isolated from PBMCs of these subjects was quantified by quantitative RT-PCR. Anthropometric measurements and biochemical profiles were assessed for each individual. In women, LL-37 mRNA expression was significantly and positively correlated with body mass index (BMI) (p

Effects of polymorphism on the microenvironment of the LDL receptor-binding region of human apoE.

To understand the molecular basis for the differences in receptor-binding activity of the three common human apolipoprotein E (apoE) isoforms, we characterized the microenvironments of their LDL receptor (LDLR)-binding regions (residues 136;-150). When present in dimyristoyl phosphatidylcholine (DMPC) complexes, the 22-kDa amino-terminal fragments (residues 1;-191) of apoE3 and apoE4 bound to the LDLR with approximately 100-fold greater affinity than the 22-kDa fragment of apoE2. The pK(a) values of lysines (K) at positions 143 and 146 in the LDLR-binding region in DMPC-associated 22-kDa apoE fragments were 9.4 and 9.9 in apoE2, 9.5 and 9.2 in apoE3, and 9.9 and 9.4 in apoE4, respectively. The increased pK(a) of K146 in apoE2 relative to apoE3 arises from a reduction in the positive electrostatic potential in its microenvironment. This effect occurs because C158 in apoE2, unlike R158 in apoE3, rearranges the intrahelical salt bridges along the polar face of the amphipathic alpha-helix spanning the LDLR-binding region, reducing the effect of the R150 positive charge on K146 and concomitantly decreasing LDLR-binding affinity. The C112R mutation in apoE4 that differentiates it from apoE3 did not perturb the pK(a) of K146 significantly, but it increased the pK(a) of K143 in apoE4 by 0.4 pH unit. This change did not alter LDLR-binding affinity. Therefore, maintaining the appropriate positive charge at the C-terminal end of the receptor-binding region is particularly critical for effective interaction with acidic residues on the LDLR.

Effects of lipid interaction on the lysine microenvironments in apolipoprotein E.

Lysines in apolipoprotein (apo) E are key factors in the binding of apoE to the low density lipoprotein receptor, and high affinity binding requires that apoE be associated with lipid. To gain insight into this effect, we examined the microenvironments of the eight lysines in the 22-kDa fragment of apoE3 (residues 1-191) in the lipid-free and lipid-associated states. As shown by (1)H,(13)C heteronuclear single quantum coherence nuclear magnetic resonance, lysine resonances in the lipid-free fragment were poorly resolved over a wide pH range, whereas in apoE3.dimyristoyl phosphatidylcholine (DMPC) discs, the lysine microenvironments and protein conformation were significantly altered. Sequence-specific assignments of the lysine resonances in the spectrum of the lipidated 22-kDa fragment were made. In the lipid-free protein, six lysines could be resolved, and all had pK(a) values above 10. In apoE3.DMPC complexes, however, all eight lysines were resolved, and the pK(a) values were 9.2-11.1. Lys-143 and Lys-146, both in the receptor binding region in helix 4, had unusually low pK(a) values of 9.5 and 9.2, respectively, likely as a result of local increases in positive electrostatic potential with lipid association. Shift reagent experiments with potassium ferricyanide showed that Lys-143 and Lys-146 were much more accessible to the ferricyanide anion in the apoE3.DMPC complex than in the lipid-free state. The angle of the nonpolar face of helix 4 is smaller than the angles of helices 1, 2, and 3, suggesting that helix 4 cannot penetrate as deeply into the DMPC acyl chains at the edge of the complex and that its polar face protrudes from the edge of the disc. This increased exposure and the greater positive electrostatic potential created by interaction with DMPC may explain why lipid association is required for high affinity binding of apoE to the low density lipoprotein receptor.

Apolipoprotein E;-low density lipoprotein receptor interaction. Influences of basic residue and amphipathic alpha-helix organization in the ligand.

Conserved lysines and arginines within amino acids 140-150 of apolipoprotein (apo) E are crucial for the interaction between apoE and the low density lipoprotein receptor (LDLR). To explore the roles of amphipathic alpha-helix and basic residue organization in the binding process, we performed site-directed mutagenesis on the 22-kDa fragment of apoE (amino acids 1-191). Exchange of lysine and arginine at positions 143, 146, and 147 demonstrated that a positive charge rather than a specific basic residue is required at these positions. Consistent with this finding, substitution of neutral amino acids for the lysines at positions 143 and 146 reduced the binding affinity to about 30% of the wild-type value. This reduction corresponds to a decrease in free energy of binding of approximately 600 cal/mol, consistent with the elimination of a hydrogen-bonded ion pair (salt bridge) between a lysine on apoE and an acidic residue on the LDLR. Binding activity was similarly reduced when K143 and K146 were both mutated to arginine (K143R + K146R), indicating that more than the side-chain positive charge can be important.Exchanging lysines and leucines indicated that the amphipathic alpha-helical structure of amino acids 140-150 is critical for normal binding to the low density lipoprotein receptor.

Apolipoprotein-mediated plasma membrane microsolubilization. Role of lipid affinity and membrane penetration in the efflux of cellular cholesterol and phospholipid.

Lipid-free apolipoprotein (apo) A-I contributes to the reverse transport of cholesterol from the periphery to the liver by solubilizing plasma membrane phospholipid and cholesterol. The features of the apolipoprotein required for this process are not understood and are addressed in the current study. Membrane microsolubilization of human fibroblasts is not specific for apo A-I; unlipidated apos A-II, C, and E incubated with the fibroblast monolayers at a saturating concentration of 50 micrograms/ml are all able to release cholesterol and phospholipid similarly. To determine the properties of the apolipoprotein that drive the process, apo A-I peptides spanning the entire sequence of the protein were utilized; the peptides correspond to the 11- and 22-residue amphipathic alpha-helical segments, as well as adjacent combinations of the helices. Of the 20 helical peptides examined, only peptides representing the N-and C-terminal portions of the protein had the ability to solubilize phospholipid and cholesterol. Cholesterol efflux to the most effective peptides, 44-65 and 209-241, was approximately 50 and 70%, respectively, of that to intact apo A-I. Deletion mutants of apo E and apo A-I were constructed that have reduced lipid binding affinities as compared with the intact molecule. The proteins, apo A-I (Delta222-243), apo A-I (Delta190-243), apo E3 (Delta192-299) and apo E4 (Delta192-299) all exhibited a decreased ability to remove cellular cholesterol and phospholipid. These decreases correlated with the reduced ability of these proteins to penetrate into a phospholipid monomolecular film. Overall, the results indicate that insertion of amphipathic alpha-helices between the plasma membrane phospholipid molecules is a required step in the mechanism of apolipoprotein-mediated cellular lipid efflux. Therefore the lipid binding ability of the apolipoprotein is critical for efficient membrane microsolubilization.

The full induction of human apoprotein A-I gene expression by the experimental nephrotic syndrome in transgenic mice depends on cis-acting elements in the proximal 256 base-pair promoter region and the trans-acting factor early growth response factor 1.

To identify molecular factors regulating apo A-I production in vivo, we induced in transgenic mice the experimental nephrotic syndrome, which results in elevated levels of HDL cholesterol (HDL-C), plasma apo A-I, and hepatic apo A-I mRNA. Human (h) apo A-I transgenic mice with different length 5' flanking sequences (5.5 or 0.256 kb, the core promoter for hepatic-specific basal expression) were injected with nephrotoxic (NTS) or control serum. With nephrosis, there were comparable (greater than twofold) increases in both lines of HDL-C, h-apo A-I, and hepatic h-apo A-I mRNA, suggesting that cis-acting elements regulating induced apo A-I gene expression were within its core promoter. Hepatic nuclear extracts from control and nephrotic mice footprinted the core promoter similarly, implying that the same elements regulated basal and induced expression. Hepatic mRNA levels for hepatocyte nuclear factor (HNF) 4 and early growth response factor (EGR) 1, trans-acting factors that bind to the core promoter, were measured: HNF4 mRNA was not affected, but that of EGR-1 was elevated approximately fivefold in the nephrotic group. EGR-1 knockout (EGR1-KO) mice or mice expressing EGR-1 were injected with either NTS or control serum. Levels of HDL-C, apo A-I, and hepatic apo A-I mRNA were lowest in nonnephrotic EGR1-KO mice and highest in nephrotic mice expressing EGR-1. Although in EGR1-KO mice HDL-C, apo A-I, and apo A-I mRNA levels also increased after NTS injection, they were approximately half of those in the nephrotic EGR-1-expressing mice. We conclude that in this model, basal and induced apo A-I gene expression in vivo are regulated by the trans-acting factor EGR-1 and require the same cis-acting elements in the core promoter.

DNA polymorphisms of human apolipoprotein A-IV gene: frequency and effects on lipid, lipoprotein and apolipoprotein levels in a French population.

Genetic polymorphisms of apolipoprotein (apo) A-IV have been shown to influence lipoprotein metabolism in some human populations. In this study, we have evaluated the physiological effect of three apo A-IV polymorphisms (Gln360- > His, Thr347- > Ser and XbaI within the second intron of the apo A-IV gene), in a French population, on seven quantitative traits: total cholesterol and triglycerides, cholesterol of HDL, apo A-IV, apo B, apo A-I and glucose. The polymorphism at amino-acid 360 was determined by direct analysis of polymerase chain reaction products. The allele frequencies were 0.92 for the A-IV1 and 0.08 for the A-IV2 allele. The genetic polymorphism at codon 347 was investigated by allele-specific oligonucleotide hybridization. The allele frequencies of the two alleles, A-IV347Thr and A-IV347Ser, were 0.78 and 0.22, respectively. The XbaI polymorphism was investigated by polymerase chain reaction followed by XbaI restriction enzyme digestion of the amplified products. The frequencies of the two apo A-IV alleles, XbaI-1 and XbaI-2, were 0.79 and 0.21, respectively. None of the three apo A-IV polymorphisms had a significant effect on lipoprotein, apolipoprotein and glucose levels.

Sources of variability of human plasma apolipoprotein A-IV levels and relationships with lipid metabolism.

Plasma apolipoprotein (apo) A-IV concentration was determined by immunoelectrophoretic assay (EIA) in 119 nuclear families. No significant effect of concomitants such as age, weight, height, body mass index, tobacco, and alcohol consumption was observed on apo A-IV levels in men and in boys. In women, contraceptive use and hormonal status affected apo A-IV levels. In girls, only age influenced the quantitative phenotype. After adjusting by specific concomitants significant correlations were observed between apo A-IV levels and triglycerides, apolipoprotein A-I and apo B levels, suggesting a role of apolipoprotein A-IV in the hepatic lipid metabolism. Intrafamilial correlations were estimated to investigate the plausibility of a common family factor. The results obtained in this study showed a significant correlation between family members with the exception of mother-daughter pairs. Using a variance components model, the contribution of genetic and environmental factors was then investigated. Different statistical models were used and two major hypotheses were statistically acceptable: the first hypothesis supports that shared and specific environmental factors explain 35 and 65%, respectively, of the total adjusted plasma apo A-IV variation. The fraction of apo A-IV variability attributable to genetic factors was null. The second hypothesis supports that the fraction of variability attributable to apo A-IV genetic variation is 67% and the common spouse environmental factors are responsible for 33% of the total variability and no specific environmental effect was found. Among the two hypotheses, taking account of the metabolism function, we support the first one without excluding gene-environment interactions which could mask the genetic influence.

The role of genetics in defining reference values and health status.

Since its establishment, the Center for Preventive Medicine in Vandoeuvre-les-Nancy, France, performed specific studies on healthy humans, and its approach was very useful for defining reference values. Prevention should extend its interest to chronic diseases. The majority of important adult disorders are partially genetically determined. Genetic markers are also useful as exclusion or as partition criteria in the production of reference values. Results are presented that were obtained for apolipoproteins E, B and AIV, frequencies of these polymorphisms in the Lorraine population, and relationships between these polymorphisms and lipid metabolism-related parameters. Health checkup centers, in particular those involved in family screening, are well suited for resembling many data concerning environmental factors: tobacco consumption, alimentation habits, or alcohol and drug consumption. Simultaneous determination of genetic markers could allow the determination of an individual's susceptibility or resistance to developing a disease and to prepare a preventive action.

A rapid and reliable method for direct genotyping of codon 360 in the human apolipoprotein A-IV gene.

Human apolipoprotein A-IV exhibits a polymorphism, first investigated at the protein level, that is caused by a single amino acid substitution of glutamine to histidine at codon 360. Detection of this polymorphism requires polymerase chain reaction (PCR) and direct sequencing of the amplified products, radiolabeled allele-specific oligonucleotides (ASOs) technique, or restriction enzyme analysis of the amplified products. However, these techniques involve the use of radioactivity and/or are not well suited to the rapid processing of a large number of samples. In this paper, we propose a new technique, a bispecific-allele primer amplification, in which a simple electrophoresis of PCR products is used for typing the variation at codon 360. The 3' primer of PCR hybridizes with one or other homologous sequence in the apoA-IV gene, depending on the presence or the absence of the mutation. This differential hybridization of the primer is used for typing the variation. In order to demonstrate the validity of this system, 120 individuals phenotyped by two-dimensional electrophoresis and genotyped by ASO were analyzed by this new technique. The results obtained by the latter method are in agreement with those found by the other techniques. However, this method is simple, more reliable, and will facilitate population studies without using radioactive materials.