Influence of the Bioactive Diet Components on the Gene Expression Regulation

Diet bioactive components, in the concept of nutrigenetics and nutrigenomics, consist of food constituents, which can transfer information from the external environment and influence gene expression in the cell and thus the function of the whole organism. It is crucial to regard food not only as the source of energy and basic nutriments, crucial for living and organism development, but also as the factor influencing health/disease, biochemical mechanisms, and activation of biochemical pathways. Bioactive components of the diet regulate gene expression through changes in the chromatin structure (including DNA methylation and histone modification), non-coding RNA, activation of transcription factors by signalling cascades, or direct ligand binding to the nuclear receptors. Analysis of interactions between diet components and human genome structure and gene activity is a modern approach that will help to better understand these relations and will allow designing dietary guidances, which can help maintain good health.

Endothelium-Derived Hyperpolarizing Factor (EDHF) Mediates Acetylsalicylic Acid (Aspirin) Vasodilation of Pregnant Rat Mesenteric Arteries

Acetylsalicylic acid (aspirin) exhibits a broad range of activities, including analgesic, antipyretic, and antiplatelet properties. Recent clinical studies also recommend aspirin prophylaxis in women with a high risk of pre-eclampsia, a major complication of pregnancy characterized by hypertension. We investigated the effect of aspirin on mesenteric resistance arteries and found outdiscovered the molecular mechanism underlying this action. Aspirin (10⁻¹²–10⁻⁶ M) was tested on pregnant rat mesenteric resistance arteries by a pressurized arteriography. Aspirin was investigated in the presence of several inhibitors of: (a) nitric oxide synthase (L-NAME 2 × 10⁻⁴ M); (b) cyclooxygenase (Indomethacin, 10⁻⁵ M); (c) Ca²⁺-activated K⁺ channels (Kca): small conductance (SKca, Apamin, 10⁻⁷ M), intermediate conductance (IKca, TRAM34, 10⁻⁵ M), and big conductance (BKca, paxilline, 10⁻⁵ M); and (d) endothelial-derived hyperpolarizing factor (high KCl, 80 mM). Aspirin caused a concentration-dependent vasodilation. Aspirin-vasodilation was abolished by removal of endothelium or by high KCl. Furthermore, preincubation with either apamin plus TRAM-34 or paxillin significantly attenuated aspirin vasodilation (p < 0.05). For the first time, we showed that aspirin induced endothelium-dependent vasodilation in mesenteric resistance arteries through the endothelial-derived hyperpolarizing factor (EDHF) and calcium-activated potassium channels. By activating this molecular mechanism, aspirin may lower peripheral vascular resistance and be beneficial in pregnancies complicated by hypertension.

Vasodilation and blood pressure-lowering effect mediated by 5,6-EEQ lactone in 5/6 nephrectomy hypertensive rats

Microvascular dysfunction is a key contributor to vascular hypertension, one of the most common chronic diseases in the world. Microvascular dysfunction leads to the loss of nitric oxide-mediated endothelial dilation and the subsequent compensatory function of endothelium-derived hyperpolarizing (EDH) factors in the regulation of vascular tone. Previously, we showed that lactone metabolite derived from arachidonic acid induces endothelial-dependent vasodilation in isolated human microvessels. Based on structural similarities, we hypothesize that additional lactone metabolites formed from eicosapentaenoic fatty acid (EPA) may bear EDH properties.

AIM

To elucidate the vasodilatory and blood pressure (BP)-reducing characteristics of the 5,6-EEQ (5,6-epoxyeicosatetraenoic acids) lactone (EPA-L) in hypertensive 5/6 nephrectomy (5/6Nx) rats.

METHODS

5/6Nx hypertensive rats intravenously administrated with EPA-L for five days. BP, blood and urine chemistry, and kidney function were detected and analyzed. Vascular dilation was detected using a pressure myograph with or without Ca²⁺ - activated K⁺ (K_Ca) endothelial channel inhibitors. KCNN3 and KCNN4 gene expression (mRNA) detected in mesenteric arteries from 5/6Nx and NT rats.

RESULTS

EPA-L administration to 5/6Nx rats significantly (p < 0.05) reduced BP and heart rate without affecting kidney function. 5/6Nx rat mesenteric arterioles exhibited a lower dilation response to acetylcholine (10^-7 mol/l) than normotensive (NT) vessels, while EPA-L administration restored the vessel relaxation response. The EPA-L-driven relaxation of mesenteric arteries was significantly reduced by pretreatment with TRAM-34 and apamin. However, K_Ca channel expression did not significantly differ between 5/6Nx and NT mesenteric arteries.

CONCLUSION

EPA-L reduces BP by improving microvessel dilation involving calcium-dependent potassium endothelial channels.

Using biological factors to individualize interventions for youth with conduct problems: Current state and ethical issues

A growing body of evidence suggests that biological factors such as genes, hormone levels, brain structure, and brain functioning influence the development and trajectory of conduct problems in youth. In addition, biological factors affect how individuals respond to the environment, including how individuals respond to programs designed to prevent or treat conduct problems. Programs designed to reduce behavior problems in youth would have the greatest impact if they were targeted toward youth who need it the most (e.g., who are mostly likely to demonstrate persistent behavior problems) as well as youth who may benefit the most from the program. Biological information may improve our ability to make decisions about which type or level of intervention is best for a particular child, thus maximizing overall effectiveness, but it also raises a number of ethical concerns. These include the idea that we may be providing fewer services to some youth based on biological factors, and that information about biological risk could potentially lead to discrimination or labeling. In this article, I discuss the risks and benefits of using biological information to individualize interventions for youth with conduct problems.

Regulation of specialised metabolites in Actinobacteria - expanding the paradigms

The increase in availability of actinobacterial whole genome sequences has revealed huge numbers of specialised metabolite biosynthetic gene clusters, encoding a range of bioactive molecules such as antibiotics, antifungals, immunosuppressives and anticancer agents. Yet the majority of these clusters are not expressed under standard laboratory conditions in rich media. Emerging data from studies of specialised metabolite biosynthesis suggest that the diversity of regulatory mechanisms is greater than previously thought and these act at multiple levels, through a range of signals such as nutrient limitation, intercellular signalling and competition with other organisms. Understanding the regulation and environmental cues that lead to the production of these compounds allows us to identify the role that these compounds play in their natural habitat as well as provide tools to exploit this untapped source of specialised metabolites for therapeutic uses. Here, we provide an overview of novel regulatory mechanisms that act in physiological, global and cluster-specific regulatory manners on biosynthetic pathways in Actinobacteria and consider these alongside their ecological and evolutionary implications.

Divergent roles of endothelial nitric oxide synthases system in maintaining cardiovascular homeostasis

Accumulating evidence has demonstrated the importance of reactive oxygen species (ROS) as an essential second messenger in health and disease. Endothelial dysfunction is the hallmark of atherosclerotic cardiovascular diseases, in which pathological levels of ROS are substantially involved. The endothelium plays a crucial role in modulating tone of underlying vascular smooth muscle by synthesizing and releasing nitric oxide (NO) and endothelium-dependent hyperpolarization (EDH) factors in a distinct vessel size-dependent manner through the diverse roles of the endothelial NO synthases (NOSs) system. Endothelium-derived hydrogen peroxide (H₂O₂) is a physiological signaling molecule serving as one of the major EDH factors especially in microcirculations and has gained increasing attention in view of its emerging relevance for cardiovascular homeostasis. In the clinical settings, it has been reported that antioxidant supplements are unexpectedly ineffective to prevent cardiovascular events. These lines of evidence indicate the potential importance of the physiological balance between NO and H₂O₂/EDH through the diverse functions of endothelial NOSs system in maintaining cardiovascular homeostasis. A better understanding of cardiovascular redox signaling is certainly needed to develop novel therapeutic strategies in cardiovascular medicine. In this review, we will briefly summarize the current knowledge on the emerging regulatory roles of redox signaling pathways in cardiovascular homeostasis, with particular focus on the two endothelial NOSs-derived mediators, NO and H₂O₂/EDH.

Biosynthesis of vitamins and cofactors in bacterium-harbouring trypanosomatids depends on the symbiotic association as revealed by genomic analyses

Some non-pathogenic trypanosomatids maintain a mutualistic relationship with a betaproteobacterium of the Alcaligenaceae family. Intensive nutritional exchanges have been reported between the two partners, indicating that these protozoa are excellent biological models to study metabolic co-evolution. We previously sequenced and herein investigate the entire genomes of five trypanosomatids which harbor a symbiotic bacterium (SHTs for Symbiont-Haboring Trypanosomatids) and the respective bacteria (TPEs for Trypanosomatid Proteobacterial Endosymbiont), as well as two trypanosomatids without symbionts (RTsfor Regular Trypanosomatids), for the presence of genes of the classical pathways for vitamin biosynthesis. Our data show that genes for the biosynthetic pathways of thiamine, biotin, and nicotinic acid are absent from all trypanosomatid genomes. This is in agreement with the absolute growth requirement for these vitamins in all protozoa of the family. Also absent from the genomes of RTs are the genes for the synthesis of pantothenic acid, folic acid, riboflavin, and vitamin B_6. This is also in agreement with the available data showing that RTs are auxotrophic for these essential vitamins. On the other hand, SHTs are autotrophic for such vitamins. Indeed, all the genes of the corresponding biosynthetic pathways were identified, most of them in the symbiont genomes, while a few genes, mostly of eukaryotic origin, were found in the host genomes. The only exceptions to the latter are: the gene coding for the enzyme ketopantoate reductase (EC:1.1.1.169) which is related instead to the Firmicutes bacteria; and two other genes, one involved in the salvage pathway of pantothenic acid and the other in the synthesis of ubiquinone, that are related to Gammaproteobacteria. Their presence in trypanosomatids may result from lateral gene transfer. Taken together, our results reinforce the idea that the low nutritional requirement of SHTs is associated with the presence of the symbiotic bacterium, which contains most genes for vitamin production.

The great screen anomaly--a new frontier in product discovery through functional metagenomics

Functional metagenomics, the study of the collective genome of a microbial community by expressing it in a foreign host, is an emerging field in biotechnology. Over the past years, the possibility of novel product discovery through metagenomics has developed rapidly. Thus, metagenomics has been heralded as a promising mining strategy of resources for the biotechnological and pharmaceutical industry. However, in spite of innovative work in the field of functional genomics in recent years, yields from function-based metagenomics studies still fall short of producing significant amounts of new products that are valuable for biotechnological processes. Thus, a new set of strategies is required with respect to fostering gene expression in comparison to the traditional work. These new strategies should address a major issue, that is, how to successfully express a set of unknown genes of unknown origin in a foreign host in high throughput. This article is an opinionating review of functional metagenomic screening of natural microbial communities, with a focus on the optimization of new product discovery. It first summarizes current major bottlenecks in functional metagenomics and then provides an overview of the general metagenomic assessment strategies, with a focus on the challenges that are met in the screening for, and selection of, target genes in metagenomic libraries. To identify possible screening limitations, strategies to achieve optimal gene expression are reviewed, examining the molecular events all the way from the transcription level through to the secretion of the target gene product.

Identification and functional characterization of Dicer2 and five single VWC domain proteins of Litopenaeus vannamei

Dicer (Dcr) is the key protein of the RNA interference (RNAi) pathway. To investigate the role of the RNAi pathway in shrimp anti-viral immunity, Litopenaeus vannamei Dcr2 (designated as LvDcr2) was identified and characterized. The full-length cDNA of LvDcr2 was 5513bp long, with an open reading frame encoding a putative protein of 1502 amino acids. In addition, five proteins homologous to the single von Willebrand factor type C (VWC) domain protein (SVC) were also identified in L. vannamei and named LvSVC1-5. These LvSVCs were between 102 and 190 amino acids in length and all contained a motif similar to Drosophila melanogaster SVC proteins (DmSVCs). By co-immunoprecipitation assays and pull-down assays, we demonstrated that LvDcr2, L. vannamei Argonaute 2 (LvAgo2), and L. vannamei transactivating response RNA-binding protein isoform 1 (LvTRBP1) interacted with each other. A luciferase reporter assay indicated that the promoters of LvSVC1, LvSVC4, LvSVC5, and DmSVC Vago (DmVago) were activated by LvDcr2 as well as by Drosophila Dcr2 (DmDcr2). Real-time RT-PCR showed that LvDcr2 and LvSVCs were up-regulated in immune responses against Poly(C-G) or WSSV challenge. These results suggested that LvDcr2 formed complexes with LvAgo2 and LvTRBP1 to act as the cores of shrimp small interfering RNA (siRNA)-induced silencing complex (siRISC)/siRISC-loading complex (siRLC), role in shrimp siRNA pathway. Furthermore, these results also suggested that LvDcr2 may engage in non-specific activation of anti-viral immunity.

Crucial importance of the endothelial K+ channel SK3 and connexin40 in arteriolar dilations during skeletal muscle contraction

Skeletal muscle activity requires substantial increases in blood flow, and the underlying vasodilation involves endothelial activity, but the contribution of the endothelium-dependent hyperpolarizing factor (EDHF) is only poorly defined. In EDHF signaling, endothelial hyperpolarization mediated by the Ca(2+)-activated K(+) channels SK3 and IK1 is a key step and also initiates gap junction-dependent conducted dilations. We assessed the role of SK3, IK1, and connexin40 (Cx40) in muscular contraction-induced dilations in the microcirculation in vivo. Hitherto, arterioles were observed in the electrically stimulated cremaster skeletal muscle of anesthetized mice lacking SK3, IK1, or Cx40 using intravital microscopy. Genetic deficiency of SK3, but not of IK1, strongly attenuated dilations to muscular contraction. Similarly, pharmacologic blockade of SK3 by the specific blocker UCL1684 impaired such dilations in wild-type and IK1-deficient mice. In contrast, IK1 was required for acetylcholine-induced dilations. Genetic deficiency of Cx40 also attenuated dilations induced by muscular contraction but not by acetylcholine. These data support the concept that endothelial hyperpolarization through activation of SK3 contributes to exercise hyperemia and the hyperpolarization ascends the vascular tree through gap junctions formed by Cx40 to orchestrate dilation. The differential impact of SK3- and IK1-deficiency on dilations to distinct stimuli suggests stimulus-dependent activation of these endothelial channels.

Proteolytic regulatory mechanism of chemerin bioactivity

Chemerin is a novel chemoattractant recognized by chemokine-like receptor 1 (CMKLR1), a serpentine receptor expressed primarily by plasmacytoid dendritic cells, natural killer cells, and macrophages. Human prochemerin circulates in plasma as an inactive precursor. Its chemotactic activity is expressed upon cleavage of the C-terminal amino acid residues by proteases of the coagulation, fibrinolytic, and inflammatory system. The C-terminal cleavage site of prochemerin is highly conservative, indicating that the proteolytic regulation of chemerin bioactivity is a common mechanism undertaken by different species. In this review, we summarized chemerin-proteases interactions, chemerin receptors, and their importance in normal and pathologic conditions.

Biologic and clinical significance of cytokine production in B-cell malignancies

Cytokines are a group of polypeptide hormones endowed with pleiotropic biological properties. Normal B lymphocytes produce a number of these factors that subserve important regulatory functions in the combined processes of proliferation and differentiation. Also neoplastic B cells can release cytokines and, simultaneously, respond to the same factors in an autocrine circuit that supports their malignant growth. In addition, tumor cells can make use of the factors released by normal cells, either spontaneously or under the influence of inductive signals from the neoplastic cells. Inappropriate or excessive release of cytokines may have an important role in the pathophysiology of some clinical features. Thus, neutralization of cytokine biologic activity in vivo could be a therapeutic strategy for treatment of human B-cell neoplasias.

Allergen source materials: state-of-the-art

A variety of positive outcomes can be realized from validation and risk management activities (see Table 4). They are dependent on the participation of multiple functional groups including the quality unit, regulatory and legal affairs, engineering and production operations, research and development, and sales and marketing. Quality risk management is receiving increased attention in the area of public health, pharmacovigilance, and pharmaceutical manufacturing. Recent examples of its regulatory use in our industry include the assessment of the potential risks of transmissible spongiform encephalopathies (TSE) agents through contaminated products], the risks of precipitates in allergenic extracts, and the revision of the potency limits for standardized dust mite and grass allergen vaccines. Its application to allergen source material process validation activities allowed for a practical strategy, especially in a complex manufacturing environment involving hundreds of products with multiple intended uses. In addition, the use of tools such as FMEA was useful in evaluating proposed changes made to manufacturing procedures and product specifications, new regulatory actions, and customer feedback or complaints. The success of such a quality assurance programs will ultimately be reflected in the elimination or reduction of product failures, improvement in the detection and prediction of potential product failures, and increased confidence in product quality.

Inference of protein complex activities from chemical-genetic profile and its applications: predicting drug-target pathways

The chemical-genetic profile can be defined as quantitative values of deletion strains' growth defects under exposure to chemicals. In yeast, the compendium of chemical-genetic profiles of genomewide deletion strains under many different chemicals has been used for identifying direct target proteins and a common mode-of-action of those chemicals. In the previous study, valuable biological information such as protein–protein and genetic interactions has not been fully utilized. In our study, we integrated this compendium and biological interactions into the comprehensive collection of ∼490 protein complexes of yeast for model-based prediction of a drug's target proteins and similar drugs. We assumed that those protein complexes (PCs) were functional units for yeast cell growth and regarded them as hidden factors and developed the PC-based Bayesian factor model that relates the chemical-genetic profile at the level of organism phenotypes to the hidden activities of PCs at the molecular level. The inferred PC activities provided the predictive power of a common mode-of-action of drugs as well as grouping of PCs with similar functions. In addition, our PC-based model allowed us to develop a new effective method to predict a drug's target pathway, by which we were able to highlight the target-protein, TOR1, of rapamycin. Our study is the first approach to model phenotypes of systematic deletion strains in terms of protein complexes. We believe that our PC-based approach can provide an appropriate framework for combining and modeling several types of chemical-genetic profiles including interspecies. Such efforts will contribute to predicting more precisely relevant pathways including target proteins that interact directly with bioactive compounds.

Finding the specific targets of chemicals and deciphering how drugs work in our body is important for the effective development of new drugs. Growth profiles of yeast genomewide deletion strains under many different chemicals have been used for identifying target proteins and a common mode-of-action of drugs. In this study, we integrated those growth profiles with biological information such as protein–protein interactions and genetic interactions to develop a new method to infer the mode-of-action of drugs. We assume that the protein complexes (PCs) are functional units for cell growth regulation, analogous to the transcriptional factors (TFs) for gene regulation. We also assume that the relative cell growth of a specific deletion mutant in the presence of a specific drug is determined by the interactions between the PCs and the deleted gene of the mutant. We then developed a computational model with which we were able to infer the hidden activities of PCs on the cell growth and showed that yeast growth phenotypes could be effectively modeled by PCs in a biologically meaningful way by demonstrating that the inferred activities of PCs contributed to predicting groups of similar drugs as well as proteins and pathways targeted by drugs.

Strain improvement for production of pharmaceuticals and other microbial metabolites by fermentation

Microbes have been good to us. They have given us thousands of valuable products with novel structures and activities. In nature, they only produce tiny amounts of these secondary metabolic products as a matter of survival. Thus, these metabolites are not overproduced in nature, but they must be overproduced in the pharmaceutical industry. Genetic manipulations are used in industry to obtain strains that produce hundreds or thousands of times more than that produced by the originally isolated strain. These strain improvement programs traditionally employ mutagenesis followed by screening or selection; this is known as 'brute-force' technology. Today, they are supplemented by modern strategic technologies developed via advances in molecular biology, recombinant DNA technology, and genetics. The progress in strain improvement has increased fermentation productivity and decreased costs tremendously. These genetic programs also serve other goals such as the elimination of undesirable products or analogs, discovery of new antibiotics, and deciphering of biosynthetic pathways.

Biomedicinals from the phytosymbionts of marine invertebrates: A molecular approach

Marine invertebrate animals such as sponges, gorgonians, tunicates and bryozoans are sources of biomedicinally relevant natural products, a small but growing number of which are advancing through clinical trials. Most metazoan and anthozoan species harbour commensal microorganisms that include prokaryotic bacteria, cyanobacteria (blue-green algae), eukaryotic microalgae, and fungi within host tissues where they reside as extra- and intra-cellular symbionts. In some sponges these associated microbes may constitute as much as 40% of the holobiont volume. There is now abundant evidence to suggest that a significant portion of the bioactive metabolites thought originally to be products of the source animal are often synthesized by their symbiotic microbiota. Several anti-cancer metabolites from marine sponges that have progressed to pre-clinical or clinical-trial phases, such as discodermolide, halichondrin B and bryostatin 1, are thought to be products derived from their microbiotic consortia. Freshwater and marine cyanobacteria are well recognised for producing numerous and structurally diverse bioactive and cytotoxic secondary metabolites suited to drug discovery. Sea sponges often contain dominant taxa-specific populations of cyanobacteria, and it is these phytosymbionts (= photosymbionts) that are considered to be the true biogenic source of a number of pharmacologically active polyketides and nonribosomally synthesized peptides produced within the sponge. Accordingly, new collections can be pre-screened in the field for the presence of phytobionts and, together with metagenomic screening using degenerate PCR primers to identify key polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) genes, afford a biodiscovery rationale based on the therapeutic prospects of phytochemical selection. Additionally, new cloning and biosynthetic expression strategies may provide a sustainable method for the supply of new pharmaceuticals derived from the uncultured phytosymbionts of marine organisms.

Strategies to unravel the function of orphan biosynthesis pathways: recent examples and future prospects

The recent increase and availability of whole genome sequences have revised our view of the metabolic capabilities of microorganisms. From these data, a large number of orphan biosynthesis pathways have been identified by bio-informatics. Orphan biosynthetic pathways are gene clusters for which the encoded natural product is unknown. It is worthy to note that the number of orphan pathways coding for putative natural products outnumbers by far the number of currently known metabolites for a given organism. Whilst Streptomyces coelicolor was known to produce only 4 secondary metabolites, the genome analysis revealed 18 additional orphan biosynthetic pathways. It is intriguing to note that this is not a particular case because analysis of other microbial genomes originating from myxobacteria, cyanobacteria and filamentous fungi showed the presence of a comparable or even larger number of orphan pathways. The discovery of these numerous pathways represents a treasure trove, which is likely to grow exponentially in the future, uncovering many novel and possibly bio-active compounds. The few natural products that have been correlated with their orphan pathway are merely the tip of the iceberg, whilst plenty of metabolites await discovery. The recent strategies and methods to access these promising hidden natural products are discussed in this review.

Expanding the metabolic engineering toolbox: more options to engineer cells

Metabolic engineering exploits an integrated, systems-level approach for optimizing a desired cellular property or phenotype; and great strides have been made within this scope and context during the past fifteen years. However, due to limitations in the concepts and techniques, these have relied on a focused, pathway-oriented view. Recent advances in 'omics' technologies and computational systems biology have brought the foundational systems approach of metabolic engineering into focus. At the same time, protein engineering and synthetic biology have expanded the breadth and precision of the methods available to metabolic engineers to improve strain properties. Examples are presented that illustrate this broader perspective of tools and concepts, including a recent approach for global transcriptional machinery engineering (gTME), which has demonstrated the ability to elicit multigenic transcriptional changes that have improved phenotypes compared with single-gene perturbations.

Biologically inspired approaches to drug delivery for nerve regeneration

As the biological processes governing nerve regeneration have become elucidated over the past decades, interest has developed in manipulating these processes to improve nerve regeneration. Drug delivery to the regenerating nerve has the potential for major clinical applications in neurodegenerative diseases, spinal cord injury and peripheral nerve injury or sacrifice. This article reviews the evolution of the field of drug delivery to the regenerating nerve, from simple local applications of neurotrophic agents in solution and osmotic pump delivery, to the existing approaches involving novel biomaterials and genetically manipulated cell populations. A discussion of the various known nerve growth-promoting agents, and the chemical considerations involved in their delivery, is included. A perspective on the role of tissue engineering approaches for nerve regeneration in the future is offered.

Microbial genomics for the improvement of natural product discovery

The quest for the discovery of novel natural products has entered a new chapter with the enormous wealth of genetic data that is now available. This information has been exploited by using whole-genome sequence mining to uncover cryptic pathways, or biosynthetic pathways for previously undetected metabolites. Alternatively, using known paradigms for secondary metabolite biosynthesis, genetic information has been 'fished out' of DNA libraries resulting in the discovery of new natural products and isolation of gene clusters for known metabolites. Novel natural products have been discovered by expressing genetic data from uncultured organisms or difficult-to-manipulate strains in heterologous hosts. Furthermore, improvements in heterologous expression have not only helped to identify gene clusters but have also made it easier to manipulate these genes in order to generate new compounds. Finally, and perhaps the most crucial aspect of the efficient and prosperous use of the abundance of genetic information, novel enzyme chemistry continues to be discovered, which has aided our understanding of how natural products are biosynthesized de novo, and enabled us to rework the current paradigms for natural product biosynthesis.

Marine microalgae

Marine microalgae, the largest primary biomass, have been attracting attention as resources for new metabolites and biotechnologically useful genes. The diversified marine environment harbors a large variety of microalgae. In this paper, the biotechnological aspects and fundamental characteristics of marine microalgae are reviewed.

Acute changes of biventricular gene expression in volume and right ventricular pressure overload

OBJECTIVE

We investigated the effects of acute volume and RV pressure overload on biventricular function and gene expression of BNP, pro-inflammatory cytokines (IL-6 and TNF-alpha), iNOS, growth factors (IGF-1, ppET-1), ACE and Ca2+-handling proteins (SERCA2a, phospholamban and calsequestrin).

METHODS

Male Wistar rats (n=45) instrumented with pressure tip micromanometers in right (RV) and left ventricular (LV) cavities were assigned to one of three protocols: i) Acute RV pressure overload induced by pulmonary trunk banding in order to double RV peak systolic pressure, during 120 or 360 min; ii) acute volume overload induced by dextran40 infusion (5 ml/h), during 120 or 360 min; iii) Sham. RV and LV samples were collected for mRNA quantification.

RESULTS

BNP upregulation was restricted to the overloaded ventricles. TNF-alpha, IL-6, ppET-1, SERCA2a and phospholamban gene activation was higher in volume than in pressure overload. IGF-1 overexpression was similar in both types of overload, but was limited to the RV. TNF-alpha and CSQ mRNA levels were increased in the non-overloaded LV after pulmonary trunk banding. No significant changes were detected in ACE or iNOS expression. RV end-diastolic pressures positively correlated with local expression of BNP, TNF-alpha, IL-6, IGF-1, ppET-1 and SERCA2a, while RV peak systolic pressures correlated only with local expression of IL-6, IGF-1 and ppET-1.

CONCLUSIONS

Acute cardiac overload alters myocardial gene expression profile, distinctly in volume and pressure overload. These changes correlate more closely with diastolic than with systolic load. Nonetheless, gene activation is also present in the non-overloaded LV of selectively RV overloaded hearts.

The Impact of Bacterial Genomics on Natural Product Research

"There's life in the old dog yet!" This adage also holds true for natural product research. After the era of natural products was declared to be over, because of the introduction of combinatorial synthesis techniques, natural product research has taken a surprising turn back towards a major field of pharmaceutical research. Current challenges, such as emerging multidrug-resistant bacteria, might be overcome by developments which combine genomic knowledge with applied biology and chemistry to identify, produce, and alter the structure of new lead compounds. Significant biological activity is reported much less frequently for synthetic compounds, a fact reflected in the large proportion of natural products and their derivatives in clinical use. This Review describes the impact of microbial genomics on natural products research, in particularly the search for new lead structures and their optimization. The limitations of this research are also discussed, thus allowing a look into future developments.

Marine enzymes

Marine enzyme biotechnology can offer novel biocatalysts with properties like high salt tolerance, hyperthermostability, barophilicity, cold adaptivity, and ease in large-scale cultivation. This review deals with the research and development work done on the occurrence, molecular biology, and bioprocessing of marine enzymes during the last decade. Exotic locations have been accessed for the search of novel enzymes. Scientists have isolated proteases and carbohydrases from deep sea hydrothermal vents. Cold active metabolic enzymes from psychrophilic marine microorganisms have received considerable research attention. Marine symbiont microorganisms growing in association with animals and plants were shown to produce enzymes of commercial interest. Microorganisms isolated from sediment and seawater have been the most widely studied, proteases, carbohydrases, and peroxidases being noteworthy. Enzymes from marine animals and plants were primarily studied for their metabolic roles, though proteases and peroxidases have found industrial applications. Novel techniques in molecular biology applied to assess the diversity of chitinases, nitrate, nitrite, ammonia-metabolizing, and pollutant-degrading enzymes are discussed. Genes encoding chitinases, proteases, and carbohydrases from microbial and animal sources have been cloned and characterized. Research on the bioprocessing of marine-derived enzymes, however, has been scanty, focusing mainly on the application of solid-state fermentation to the production of enzymes from microbial sources.

Protein structure similarity clustering (PSSC) and natural product structure as inspiration sources for drug development and chemical genomics

Finding small molecules that modulate protein function is of primary importance in drug development and in the emerging field of chemical genomics. To facilitate the identification of such molecules, we developed a novel strategy making use of structural conservatism found in protein domain architecture and natural product inspired compound library design. Domains and proteins identified as being structurally similar in their ligand-sensing cores are grouped in a protein structure similarity cluster (PSSC). Natural products can be considered as evolutionary pre-validated ligands for multiple proteins and therefore natural products that are known to interact with one of the PSSC member proteins are selected as guiding structures for compound library synthesis. Application of this novel strategy for compound library design provided enhanced hit rates in small compound libraries for structurally similar proteins.

Angiopoietin-related growth factor antagonizes obesity and insulin resistance

Angiopoietin-related growth factor (AGF), a member of the angiopoietin-like protein (Angptl) family, is secreted predominantly from the liver into the systemic circulation. Here, we show that most (>80%) of the AGF-deficient mice die at about embryonic day 13, whereas the surviving AGF-deficient mice develop marked obesity, lipid accumulation in skeletal muscle and liver, and insulin resistance accompanied by reduced energy expenditure relative to controls. In parallel, mice with targeted activation of AGF show leanness and increased insulin sensitivity resulting from increased energy expenditure. They are also protected from high-fat diet-induced obesity, insulin resistance and nonadipose tissue steatosis. Hepatic overexpression of AGF by adenoviral transduction, which leads to an approximately 2.5-fold increase in serum AGF concentrations, results in a significant (P < 0.01) body weight loss and increases insulin sensitivity in mice fed a high-fat diet. This study establishes AGF as a new hepatocyte-derived circulating factor that counteracts obesity and related insulin resistance.

Novel natural compounds obtained by genome-based screening and genetic engineering

Despite the fact that drugs derived from natural products have revolutionized medicine in the past, they are currently going through a phase of reduced interest in drug discovery. At the same time, however, there is an urgent medical need for new drugs, since development pipelines are drying up and resistance to antibiotics and other chemotherapeutic agents is becoming an increasingly frequent problem. The development and recent progress of new technologies, such as genetic engineering and screening, offer a unique opportunity to re-establish natural products as drug leads. Examples of recent advances in the application of these technologies to the discovery and development of important novel drugs are discussed in this review.

Two breakpoint clusters at fragile site FRA3B form phased nucleosomes

Fragile sites are gaps and breaks in metaphase chromosomes generated by specific culture conditions. Fragile site FRA3B is the most unstable site and is directly involved in the breakpoints of deletion and translocation in a wide spectrum of cancers. To learn about the general characteristics of common fragile sites, we investigated the chromatin structure of the FRA3B site. Because FRA3B spans several hundred kilobases, we focused our study on two breakpoint clusters found in FRA3B. Using various nucleases, we demonstrated that these two regions contain phased nucleosomes, regardless of treatment with aphidicolin. Because these regions are located in intron 4 of the FHIT gene, it is very interesting to observe phased nucleosomes over these regions, which are several hundred kilobases downstream from the promoter. Further, by using nucleosome assembly assays, we demonstrate that these two regions do not contain strong nucleosome positioning elements. These results suggest that other factors appear to cooperate with the DNA sequence of these regions to impart nucleosome phasing. This study provides the first information on the chromatin structure of breakpoint regions in a common fragile site. The observation of phased nucleosomes over these breakpoint regions could offer a foundation to understand the expression of fragile sites.

T-cell-targeted biologicals for psoriasis

Psoriasis is now accepted as a T-cell-mediated disease and that targeting of T cell function and/or trafficking is a logical approach to therapy. As a consequence of recombinant DNA technologies biologic therapies are synthesisable in sufficient quantities for clinical use. The original proof of concept for T-cell-targeted therapies in psoriasis came with the demonstration that anti-CD4 monoclonal antibodies were effective. Progress is such that two T-cell-directed biologicals - alefacept and efalizumab - have recently been approved in the U.S.A. for the treatment of psoriasis. In addition to providing new therapies the T-cell-targeted biologicals with their selective approach can be used as sophisticated tools to dissect out and help our understanding of key pathomechanisms in psoriasis; the non - efficacy of anti - E-selectin is a case in point. It is likely that the most appropriate place for T-cell-directed biologicals in the management of chronic plaque psoriasis will be for maintenance, rather than induction, of remission. This is a reflection of mode of action and relative safety for long-term administration.

ALTERED ARTERIAL HOMEOSTASIS AND CEREBRAL ANEURYSMS: A MOLECULAR EPIDEMIOLOGY STUDY

OBJECTIVE

We hypothesized that patients with intracranial cerebral aneurysms (IAs) harbor a molecular defect in the process responsible for maintaining arterial integrity (arterial homeostasis). In this study, we undertook a preliminary assessment of differential expression of key molecules involved with each phase of homeostasis: arterial flow modulation, arterial tear and repair, and the ensuing extracellular matrix.

METHODS

Key molecules from each phase of the arterial homeostatic process were selected: prostacyclin-stimulating factor, implicated with arterial flow modulation; PNUT and RAI, involved with tissue repair and arterial remodeling; and Type III collagen and fibronectin, which are key constituents of the extracellular matrix. A small sample of the IA dome was harvested at the time of surgical repair from both ruptured and unruptured domes. Pericranial vascular tissue was harvested from a sample of the superficial temporal artery (STA) or occipital artery from aneurysmal and nonaneurysmal patients undergoing craniotomy for unrelated conditions. Statistical analysis examining expression of each marker was performed initially using dichotomous analysis (presence or absence of expression), followed by an assessment of quantitative differences in expression. Initial analysis was restricted to the pair consisting of dome and STA harvested from each individual patient. This was followed by a pooled analysis in which all domes and STAs were respectively pooled.

RESULTS

A total of 86 tissue samples were studied, including 24 IA domes, STA samples from 43 aneurysmal patients, and STA samples from 19 nonaneurysmal patients. We found that the degree of prostacyclin-stimulating factor and RAI expression was reduced in ruptured aneurysm domes when compared with STAs from IA patients (odds ratio, 0.26; 95% confidence interval [CI], 0.08-0.89; and odds ratio, 0.18; 95% CI, 0.03-0.94, respectively). Type III collagen expression also was reduced among ruptured domes when compared with STA (P = 0.042). These differences were found to be independent of the effects of smoking with adjusted odds ratios of 0.25 (95% CI, 0.08-0.77) and 0.18 (95% CI, 0.04-0.79), respectively, for prostacyclin-stimulating factor and RAI. No statistically significant differences were noted among the unruptured domes.

CONCLUSION

These preliminary data suggest an impaired ability to express proteins responsible for flow modulation and arterial repair within the ruptured domes when compared with control pericranial tissue. The study generates a hypothesis of impaired arterial homeostasis with a reduced ability to modulate hemodynamic flow with perhaps increased microinjury. This is exacerbated further by an impaired molecular ability to repair the vessel wall, culminating in aneurysm rupture. The study has limitations based on the use of pericranial tissue as the control and the relatively small sample size. Nevertheless, this study suggests that altered arterial homeostasis warrants further investigation in hopes of better understanding IA pathogenesis.

Angiopoietin-related growth factor (AGF) promotes angiogenesis

We report here the identification of angiopoietin-related growth factor (AGF) as a positive mediator for angiogenesis. To investigate the biologic function of AGF in angiogenesis, we analyzed the vasculature in the dermis of transgenic mice expressing AGF in mouse epidermal keratinocytes (K14-AGF). K14-AGF transgenic mice were grossly red, especially in the ears and snout, suggesting that hypervascularization had occurred in their skin. Histologic examination of ear skin from K14-AGF transgenic mice revealed increased numbers of microvessels in the dermis, whereas the expression of several angiogenic factors, such as basic fibroblast growth factor (bFGF), vascular endothelial growth factors (VEGFs), and angiopoietin-1 (Ang-1), was decreased. We showed that AGF is a secreted protein and does not bind to tyrosine kinase with immunoglobulin and EGF-homology domain (Tie1) or Tie2 receptors. An in vitro chamber assay revealed that AGF directly promotes chemotactic activity of vascular endothelial cells. Both mouse corneal and matrigel plug assays showed that AGF induces neovascularization in vivo. Furthermore, we found that plasma leakage occurred after direct injection of AGF into the mouse dermis, suggesting that AGF directly induces a permeability change in the local vasculature. On the basis of these observations, we propose that AGF is a novel angiogenic factor and that handling of its biologic functions could lead to novel therapeutic strategies for control of angiogenesis.

Approaches to identify, clone, and express symbiont bioactive metabolite genes

This review discusses approaches to identify, clone, and express bioactive metabolite genes from symbionts of marine invertebrates. Criteria for proving symbiotic origin of bioactive metabolites are presented, followed by a comprehensive, practically-oriented overview of techniques to be applied. The Bugula neritina/Endobugula sertula association is used as a primary example, but other symbioses are discussed. Thirty-six compounds are presented and 111 references are cited.

Merging the potential of microbial genetics with biological and chemical diversity: an even brighter future for marine natural product drug discovery

Marine invertebrates and a growing number of marine bacteria are the sources of novel, bioactive secondary metabolites. Structurally, many of these compounds appear to be biosynthesized by polyketide synthases (PKS) and/or nonribosomal peptide synthetases (NRPS) that have also been found in terrestrial microbes. This review highlights scientific advances from 1999-2003 in the emerging field of molecular genetics of polyketide and nonribosomal peptide natural products isolated from marine organisms. The implications of this research towards the development of marine secondary metabolites as a sustainable source of new drugs are discussed.

Angiopoietin-related growth factor (AGF) promotes epidermal proliferation, remodeling, and regeneration

We report here the identification of an angiopoietin-related growth factor (AGF). To examine the biological function of AGF in vivo, we created transgenic mice expressing AGF in epidermal keratinocytes (K14-AGF). K14-AGF mice exhibited swollen and reddish ears, nose and eyelids. Histological analyses of K14-AGF mice revealed significantly thickened epidermis and a marked increase in proliferating epidermal cells as well as vascular cells in the skin compared with nontransgenic controls. In addition, we found rapid wound closure in the healing process and an unusual closure of holes punched in the ears of K14-AGF mice. Furthermore, we observed that AGF is expressed in platelets and mast cells, and detected at wounded skin, whereas there was no expression of AGF detected in normal skin tissues, suggesting that AGF derived from these infiltrated cells affects epidermal proliferation and thereby plays a role in the wound healing process. These findings demonstrate that biological functions of AGF in epidermal keratinocytes could lead to novel therapeutic strategies for wound care and epidermal regenerative medicine.

An EVH1/WH1 domain as a key actor in TGFbeta signalling

EVH1 (enabled VASP (vasodilator-stimulated protein) homology 1)/WH1 (WASP (Wiskott-Aldrich syndrome protein) homology 1) domains, present in Ena VASP and WASP, are protein interaction modules specialised in binding proline-rich ligands. An EVH1/WH1 domain is here identified in the recently cloned SMIF protein, a key protein in transforming growth factor-beta (TGFbeta) signalling which was not yet related to defined domains. The SMIF EVH1/WH1 domain interacts with the proline-rich Smad4 activation domain, leading to translocation of so-formed complex to the nucleus where SMIF possesses strong intrinsic TGFbeta-inducible transcriptional activity. This finding highlights the pivotal role that the EVH1/WH1 family of domains play in multiple eukaryotic signal transduction pathways.

Ex vivo expansion of stem and progenitor cells in co-culture of mobilized peripheral blood CD34+ cells on human endothelium transfected with adenovectors expressing thrombopoietin, c-kit ligand, and Flt-3 ligand

To optimize conditions for ex vivo expansion of adult hematopoietic stem cells, we evaluated the co-culture of G-CSF mobilized human peripheral blood (PB) CD34(+) cells with endothelial cells engineered to overexpress various hematopoietic growth factors. Immortalized human bone marrow endothelial cells (BMEC) transfected with an expression vector carrying cDNA encoding the human telomerase reverse transcriptase (hTERT) and human umbilical vein endothelial cells (HUVEC) were transfected with combinations of adenovectors expressing murine c-kit ligand (KL), human thrombopoietin (TPO), human Flt3 ligand (FL), and human granulocyte-macrophage colony-stimulating factor (GM-CSF). Ex vivo expansion of PB CD34(+) cells from normal donors and non-Hodgkin lymphoma (NHL) patients in endothelial co-culture was evaluated weekly for total cell production, progenitor (CFU-GM, BFU-E) cell production, and stem cell production as measured by Week-5 Cobblestone Area Forming Cell assay (Wk-5 CAFC). HUVEC transfected with adenovectors expressing TPO, KL, and FL provided the best co-culture system for expanding CD34(+) cells. Maximal total nuclear cell, CFU-GM, and Wk-5 CAFC production occurred between weeks 2 and 3 with 113-fold, 25-fold, and 2.2-5.5-fold expansions, respectively. We did not detect significant differences when GM-CSF was added to the co-culture system. Expansion was also obtained using recombinant human cytokines, but was not maintained beyond 3 weeks. We demonstrated that continuous generation of high levels of TPO, FL, and KL as well as other factors secreted by endothelium provided a clinically relevant co-culture method for ex vivo expansion of stem and progenitor cells from cryopreserved CD34(+) populations.

Linker-mediated recombinational subcloning of large DNA fragments using yeast

The homologous recombination pathway in yeast is an ideal tool for the sequence-specific assembly of plasmids. Complementary 80-nucleotide oligonucleotides that overlap a vector and a target fragment were found to serve as efficient recombination linkers for fragment subcloning. Using electroporation, single-stranded 80-mers were adequate for routine plasmid construction. A cycloheximide-based counterselection was introduced to increase the specificity of cloning by homologous recombination relative to nonspecific vector background. Reconstruction experiments suggest this counterselection increased cloning specificity by 100-fold. Cycloheximide counterselection was used in conjunction with 80-bp linkers to subclone targeted regions from bacterial artificial chromosomes. This technology may find broad application in the final stages of completing the Human Genome Sequencing Project and in applications of BAC clones to the functional analysis of complex genomes.

Lysophosphatidylcholine inhibits the expression of prostacyclin stimulating factor in cultured vascular smooth muscle cells

We have cloned a prostacyclin (PGI2) stimulating factor (PSF), which stimulates PGI2 production by vascular endothelial cells. Previous study demonstrated the reduced PSF expression in the coronary arteries from the patients with ischemic heart disease. To clarify the mechanism of reduced PSF expression in atherosclerosis, we examined the effect of lysophosphatidylcholine (lysoPC), a main component of oxidized low density lipoprotein (LDL), on PSF expression in cultured vascular smooth muscle cells. LysoPC reduced PSF expression dose-dependently. Whereas neither phosphatidylcholine nor native LDL affects the PSF expression. Calphostin C, a protein kinase C (PKC) inhibitor, restored the reduction of PSF expression by lysoPC. These results suggest that lysoPC-induced reduction of PSF expression is mediated by PKC activation and is playing a role in the initiation and progression of atherosclerotic lesions.

Human biological materials in research: ethical issues and the role of stewardship in minimizing research risks

Recent scientific and technologic advances generated from the human genome project have increased the ability of researchers to study human biological materials. This has enhanced the ease with which highly personal information such as genetic makeup can be revealed about individuals, families, and communities. In addition, a change in the societal value of human biological tissue from waste to commercial resource has occurred. A new model of stewardship is developed that can be used as a guide for protecting human research participants who are involved in studies that include collecting and handling human biological samples. Nursing implications to ensure protection of human research participants are discussed.

Real-time quantitative PCR for retrovirus-like particle quantification in CHO cell culture

Chinese hamster ovary (CHO) cells have been widely used to manufacture recombinant proteins intended for human therapeutic uses. Retrovirus-like particles, which are apparently defective and non-infectious, have been detected in all CHO cells by electron microscopy (EM). To assure viral safety of CHO cell-derived biologicals, quantification of retrovirus-like particles in production cell culture and demonstration of sufficient elimination of such retrovirus-like particles by the down-stream purification process are required for product market registration worldwide. EM, with a detection limit of 1x10(6) particles/ml, is the standard retrovirus-like particle quantification method. The whole process, which requires a large amount of sample (3-6 litres), is labour intensive, time consuming, expensive, and subject to significant assay variability. In this paper, a novel real-time quantitative PCR assay (TaqMan assay) has been developed for the quantification of retrovirus-like particles. Each retrovirus particle contains two copies of the viral genomic particle RNA (pRNA) molecule. Therefore, quantification of retrovirus particles can be achieved by quantifying the pRNA copy number, i.e. every two copies of retroviral pRNA is equivalent to one retrovirus-like particle. The TaqMan assay takes advantage of the 5'-->3' exonuclease activity of Taq DNA polymerase and utilizes the PRISM 7700 Sequence Detection System of PE Applied Biosystems (Foster City, CA, U.S.A.) for automated pRNA quantification through a dual-labelled fluorogenic probe. The TaqMan quantification technique is highly comparable to the EM analysis. In addition, it offers significant advantages over the EM analysis, such as a higher sensitivity of less than 600 particles/ml, greater accuracy and reliability, higher sample throughput, more flexibility and lower cost. Therefore, the TaqMan assay should be used as a substitute for EM analysis for retrovirus-like particle quantification in CHO cell-based production system.

Maturation phenotype of Sertoli cells in testicular biopsies of azoospermic men

The involvement of Sertoli cells in different spermatogenic impairments has been studied by an immunohistomorphometric technique using cytokeratin-18 (CK-18) as a marker for immature Sertoli cells. CK-18 is known to be expressed in Sertoli cells during prenatal and prepubertal differentiation and is normally lost at puberty. Forty-nine azoospermic men were included in the current study. Quantitative measurements on testicular biopsies revealed the highest CK-18 expression in the mixed atrophy biopsies (22 men), a lower expression in the Sertoli cell-only (SCO) biopsies (12 men), and minimal residual staining in the group considered as representing normal spermatogenesis (six obstructive azoospermia patients). The cytokeratin immunopositive-stained tubules were associated either with arrest in spermatogenesis or with SCO. Examination of sections from nine men with microdeletions in the AZF region of the Y chromosome revealed that these men were either negative for CK-18 expression or showed only weak residual staining. This may suggest that the spermatogenic defect in the AZF-deleted men originates in the germ cell and has no impact on Sertoli cell maturation. The cause that determined the spermatogenic defect in the other cases of male infertility with high CK-18 expression may have damaged both the Sertoli and the germ cells.

Prognostic value of Y deletion analysis: what is the clinical prognostic value of Y chromosome microdeletion analysis?

In many centres, Y chromosome deletion analysis is still not performed routinely and if so, the results are used for genetic counselling but are not considered as having a useful prognostic value. The type of deletion (AZFa, b or c) has been proposed as a potential prognostic factor for sperm retrieval in men undergoing TESE. AZFc deletions and partial AZFb deletions are associated with sperm retrieval in approximately 50% of cases while in the case of a patient with complete AZFb deletion the probability of finding mature spermatozoa is virtually nil. Therefore the extent and position of a Y microdeletion is important (complete or partial). The prognostic value of Y chromosome deletion analysis in cases of oligozoospermia is important when one considers the progressive decrease of sperm number over time in men with AZFc deletions. Cryo-conservation of spermatozoa in these cases could avoid invasive techniques, such as TESE/ICSI, in the future. Male offspring that are conceived by ICSI or IVF techniques from father with oligozoospermia or azoospermia would also benefit from knowledge of their Y status, since the identification of the genetic defect will render future medical or surgical therapies unnecessary. Y microdeletion screening is therefore important, not only to define the aetiology of spermatogenic failure, but also because it gives precious information for a more appropriate clinical management of both the infertile male and his future male child.

Cloning of the cDNA and localization of the gene encoding human NRBP, a ubiquitously expressed, multidomain putative adapter protein

Adapter proteins modulate multiple signaling pathways by regulating the aggregation of other factors into signaling complexes. Here we have identified a novel human cDNA encoding NRBP, a multidomain putative adapter protein containing (i) two putative nuclear receptor binding motifs (LXXLL), (ii) a putative binding domain for Src homology-2 (SH2) domain containing proteins, (iii) a kinase-like domain, (iv) a bipartite nuclear localization signal, and (v) three sequences rich in glutamic acid, serine, proline, and threonine (PEST) residues. The NRBP mRNA transcript, of approximately 2.4 kb, was ubiquitously expressed in a wide range of normal human tissues and 15 human tumor cell lines. The NRBP cDNA is predicted to encode a polypeptide of 535 amino acids with a molecular mass of 59.8 kDa. Translation of NRBP mRNA in vitro reveals three translation products of 60, 51, and 43 kDa, suggesting that translation of NRBP may initiate at multiple sites. The NRBP gene was localized to human chromosome 2p23, near the location of the NCOA1 gene encoding the nuclear receptor coactivator, steroid receptor coactivator-1 (SRC-1). The features of NRBP predict a function as an adapter protein potentially linking signaling pathways involving nuclear receptors and SH2 domain containing proteins.

Dependence and independence of [PSI(+)] and [PIN(+)]: a two-prion system in yeast?

The [PSI(+)] prion can be induced by overproduction of the complete Sup35 protein, but only in strains carrying the non-Mendelian [PIN(+)] determinant. Here we demonstrate that just as [psi (-)] strains can exist as [PIN(+)] and [pin(-)] variants, [PSI(+)] can also exist in the presence or absence of [PIN(+)]. [PSI(+)] and [PIN(+)] tend to be cured together, but can be lost separately. [PSI(+)]-related phenotypes are not affected by [PIN(+)]. Thus, [PIN(+)] is required for the de novo formation of [PSI(+)], not for [PSI(+)] propagation. Although [PSI(+)] induction is shown to require [PIN(+)] even when the only overexpressed region of Sup35p is the prion domain, two altered prion domain fragments circumventing the [PIN(+)] requirement are characterized. Finally, in strains cured of [PIN(+)], prolonged incubation facilitates the reappearance of [PIN(+)]. Newly appearing [PIN(+)] elements are often unstable but become stable in some mitotic progeny. Such reversibility of curing, together with our previous demonstration that the inheritance of [PIN(+)] is non-Mendelian, supports the hypothesis that [PIN(+)] is a prion. Models for [PIN(+)] action, which explain these findings, are discussed.

Recent aspects in the genetic renal mechanisms involved in hypertension

The kidney plays an important role in the blood pressure regulation primarily by modulating tubular sodium reabsorption. Various hormones, vasoactive peptides, autacoids and transporters or channels in renal tubules are involved in this process. Genes associated with renal tubular sodium handling are possibly related to the development of hypertension. Genes of the renin-angiotensin-aldosterone system are thought to be especially important as causal genes of hypertension. Na-K-ATPase, biochemically equal to Na pump, exists on the basolateral membrane of renal epithelial cells. It plays a central role in Na reabsorption and creates a driving force for transepithelial transport. Na-K-ATPase activity is regulated by adducin, a membrane-bound skeletal protein, as well as by several hormones such as dopamine, endogenous ouabain-like factor or cytochrome P450 metabolites. Genes of these factors involved in Na-K-ATPase regulation should be related to the development of hypertension. The endothelin system, atrial natriuretic peptide and nitric oxide regulate the tonus of blood vessels as well as renal sodium excretion. Several reports have indicated that genes of these substances are crucial in the pathogenesis of hypertension.