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The interplay of socioeconomic status and ethnicity on Hispanic and white men's cardiovascular disease risk and health communication patterns.

In this article, we seek to confirm past studies that document increased levels of cardiovascular disease (CVD) risk factors among White men with lower educational attainment. Second, we include a population of Hispanic men (89% Mexican American) to examine the separate and interactive effects of ethnicity and education (our measure of socioeconomic status) on CVD risk factors. Third, we examine how education and ethnicity are related to receiving health messages from print media and interpersonal channels, with the hypothesis that less educated, higher CVD risk Hispanic and White men receive fewer messages than more educated men. Finally, we examine other psychosocial variables (e.g. knowledge, self-efficacy and motivation) that may help explain observed differences in CVD risk and health communication. The study sample included 2029 men, 25-64 years of age, from three population-based, cross-sectional surveys conducted from 1979 to 1990 as part of the Stanford Five-City Project. Hispanic and White men with lower educational attainment had higher levels of CVD risk factors, and received less health information from print media and interpersonal channels than Hispanic and White men with higher educational attainment. Furthermore, less educated men from both ethnic groups reported less CVD knowledge, lower self-efficacy and lower motivation to reduce CVD risk factors than higher educated men. These results highlight the need for effective intervention programs that target low educated Hispanic and White men to decrease their disproportionate risk of CVD.

Adult↗

An exon skipping-associated nonsense mutation in the dystrophin gene uncovers a complex interplay between multiple antagonistic splicing elements.

A nonsense mutation c.4250T>A (p.Leu1417X) in the dystrophin gene of a patient with an intermediate phenotype of muscular dystrophy induces partial in-frame skipping of exon 31. On the basis of UV cross-linking assays and pull-down analysis, we present evidence that the skipping of this exon is because of the creation of an exonic splicing silencer, which acts as a highly specific binding site (UAGACA) for a known repressor protein, hnRNP A1. Recombinant hnRNP A1 represses exon inclusion both in vitro and in vivo upon transient transfection of C2C12 cells with Duchenne muscular dystrophy (DMD) minigenes carrying the c.4250T>A mutation. Furthermore, we identified a downstream splicing enhancer in the central region of exon 31. This region functions as a Tra2beta-dependent exonic splicing enhancer (ESE) in vitro when inserted into a heterologous splicing reporter, and deletion of the ESE showed that incorporation of exon 31 depends on the Tra2beta-dependent enhancer both in the wild-type and mutant context. We conclude that dystrophin exon 31 contains juxtaposed sequence motifs that collaborate to regulate exon usage. This is the first elucidation of the molecular mechanism leading to exon skipping in the dystrophin gene and allowing the occurrence of a milder phenotype than the expected DMD phenotype. The knowledge of which cis-acting sequence within an exon is important for its definition will be essential for the alternative gene therapy approaches based on modulation of splicing to bypass DMD-causing mutations in the endogenous dystrophin gene.

Amino Acid Motifs↗

xid mice reveal the interplay of homeostasis and Bruton's tyrosine kinase-mediated selection at multiple stages of B cell development.

Human X-linked agammaglobulinemia (XLA) and murine X-linked immune defect (XID) are both immunodeficiencies mediated by mutations in Bruton's tyrosine kinase (Btk), yet the developmental stage(s) affected remain controversial. To further refine the placement of the XID defect(s), we used bromodeoxyuridine labeling to determine turnover, production and transition rates of developing B cell subsets in normal, xid and xid mice expressing a human Bcl-2 transgene (xid/bcl-2). We find the xid mutation manifest at two stages of B cell development. The first is early, reducing pre-B cell production by restricting pro-B to pre-B cell transit. Surprisingly, this impairment is offset by increased survival of cells progressing from the pre- to immature B cell pool, suggesting that Btk-independent homeostatic mechanisms act to maintain this compartment. The second point of action is late, substantially reducing mature B cell production. Together, these findings reconcile apparent discrepancies in the developmental stage affected by the murine versus human lesions and suggest previously unappreciated homeostatic processes that act at the pre-B to immature B cell transition. Finally, Btk likely functions differently at these two checkpoints, since ectopic Bcl-2 expression fails to directly complement the early xid lesion, yet reverses the defect impeding final B cell maturation.

Agammaglobulinaemia Tyrosine Kinase↗

Interplay between IL-2 and IL-4 in human thymocyte differentiation: antagonism or agonism.

The effect of recombinant interleukin 2 (IL-2) and IL-4, as well as a combination of both lymphokines on human post-natal thymocytes at different maturation stages, was analyzed by culturing highly purified pro-T cells, pre-T cells, double-negative and double-positive thymocyte subsets in the presence of IL-2 and/or IL-4. Both IL-2 and IL-4 responsiveness are developmentally regulated in human thymocytes, since IL-2 and IL-4 responses decline with increasing thymocyte differentiation, double-positive T cells displaying far less proliferation than immature thymocytes. IL-2 and IL-4 may influence pro-T cell growth in both an antagonistic and additive fashion. At low doses, IL-4 inhibits IL-2-supported growth of pro-T cells, whereas, at higher concentrations, this inhibitory effect is masked by the ability of IL-4 to stimulate pro-T cell proliferation. In contrast to peripheral lymphocytes, IL-4 does not down-regulate the expression of the IL-2 receptor light chain on thymocytes. In pro-T cell cultures, IL-2 and IL-4 favour the differentiation of distinct cell populations, namely lymphocytes displaying preferentially a TCR alpha/beta+ and CD4+CD8- phenotype versus predominantly TCR gamma/delta+ and CD4-CD8+ cells, respectively. The effect of IL-2 dominates over that of IL-4, since the composition of cultures set up in the presence of IL-2 plus IL-4 resembles that of cells cultured with IL-2 alone. In synthesis, IL-2 and IL-4 exhibit reciprocal inter-relations in human thymocyte cultures, thus supporting the notion that these lymphokines are implicated in the complex regulation of a local cytokine network.

Antigens, CD↗

Interplay of J chain and disulfide bonding in assembly of polymeric IgM.

Normal mouse IgM is synthesized as hexamers in the absence of J chain and as pentamers in its presence. Previous work has suggested that polymer size is also closely related to formation of the inter-mu chain disulfide bond mediated by cysteine 414, one of three cysteines involved in inter-mu chain bonding. This correlation in turn suggested that formation of C414-C414 might be required for J chain to influence how IgM assembles and that formation of C414-C414 might affect the J chain/IgM stoichiometry. To test such hypotheses we have used cell lines which either expressed or did not express J chain to produce IgM in which serine was substituted for C414. In contrast to the case of IgM assembled from normal mu chains, IgM-S414 was secreted mostly as pentamers and tetramers but not as hexamers, irrespective of J chain synthesis. These results indicate that the role of J chain as modulator of IgM structure and function requires C414. Moreover, a more detailed analysis of the structure of J-plus and J-minus IgM-S414 revealed that J chain, in fact, influenced the nature of secreted IgM-S414: In the absence of J chain, some IgM-S414 was secreted as dimers and trimers, while in the presence of J chain, some IgM was secreted as non-covalently assembled pentamers. These results imply that disulfide bonding can occur differently from the pattern depicted in conventional models of IgM structure.

Animals↗

Interplay between the MexA-MexB-OprM multidrug efflux system and the outer membrane barrier in the multiple antibiotic resistance of Pseudomonas aeruginosa.

MexAB-OprM is a constitutively expressed multidrug efflux system of Pseudomonas aeruginosa. Using isogenic pump mutants, the contributions of the MexAB-OprM efflux pump and the outer membrane barrier to multiple antibiotic resistance were evaluated by assessing the influence of pump inactivation and outer membrane permeabilization on antibiotic susceptibility. Both pump inactivation and increased outer membrane permeability enhanced antibiotic susceptibility, although maximal susceptibility was achieved when the two were combined. Thus, inhibition of antibiotic efflux pumps and permeabilization of the outer membrane constitute an effective approach to reversing the antibiotic resistance of this organism.

Bacterial Outer Membrane Proteins↗

Interplay between the role of DNA methylation in regulating gene expression and TE-silencing in a reptilian methylome.

DNA methylation is a major component of eukaryotic genomes with an important role in the defence against transposable elements, to transcriptionally silence their activity and prevent transposition. DNA methylation also plays a major role in the regulation of gene expression. This dual role can come into conflict, where DNA methylation in gene regulatory regions becomes perturbed due to transposable element transposition, leading to disruption of gene expression. Here, we describe how this conflict is reflected in DNA methylation patterns in the sand lizard genome where there is recent transposable element activity. Using long-read sequencing technology we show that CpG islands in gene transcriptional start sites are typically hypomethylated and associated with higher gene expression. Outside transcriptional start sites, a majority of CpG islands overlapped transposable elements and were associated with hypermethylation, consistent with a host-defence role in suppressing transposition activity. We identify 605 instances where transcriptional start sites were associated with transposable elements (4.3% of all genes). These instances were far rarer in conjunction with a CpG island, when methylation signatures would be in conflict. Transposable elements were found to be closer to and at higher density the more hypermethylated a transcriptional start site was, suggesting strong selection against selfish genetic elements transposing into hypomethylated transcriptional start sites.

CpG islands↗

New evidence of iron and zinc interplay at the enterocyte and neural tissues.

Because combined iron-zinc supplementation regimens are employed with increasing frequency in field trials to combat co-occurring iron and zinc deficiencies, there is a growing concern for potential antagonisms between these 2 metals. Several supplementation trials hinted at such a competition, and the intestinal divalent metal transporter-1 (DMT1) has often been cited as a possible site for its occurrence. We summarize new evidence showing that although iron does seem to reduce the absorption of zinc, the DMT1 is an unlikely site for this absorptive antagonism by virtue of the fact that zinc is not transported by the DMT1. We also propose a shift in thinking about iron-zinc interactions from the level of enterocyte to other sites/systems in the body that may be equally relevant for the outcome and interpretation of supplementation trials. We present an overview of iron and zinc absorption and function in neural tissue as one example of possible interactions.

Animals↗

Interplay of stress and physical inactivity on muscle loss: Nutritional countermeasures.

Inactivity-mediated protein catabolism occurs in many circumstances ranging from catastrophic events such as severe illness or injury, to unique environments such as spaceflight/microgravity, to more insidious causes such as physical frailty and the progression of aging. Nevertheless, regardless of the etiology, the consequences of inactivity are readily observable and debilitating. Mechanistically, the loss of lean body mass during inactivity is the result of a chronic imbalance between muscle protein synthesis and breakdown. When inactivity is accompanied by the stress of trauma or disease, the rate of muscle protein catabolism can increase several fold. Bed rest studies in healthy volunteers provide a unique opportunity to examine the mechanisms contributing to muscle loss and evaluate strategies for intervention that may slow muscle catabolism and promote anabolism. The prerequisite for muscle protein synthesis and the most readily adaptable stimulus is dietary-derived amino acids. This review focuses on the role of amino acid supplementation in the maintenance of skeletal muscle mass during age-related and clinically mandated inactivity.

Adult↗

International research and local authorities: interplay between research and police agendas in the field of drug abuse and AIDS.

International study of drug use and HIV derives much of its value from affording investigators opportunities to compare similar behaviors in contrasting cultural contexts. In these contrasting cultural contexts, people entrusted with conducting police work and minimizing crime have ways of conducting their business that may or may not interfere with research on illegal or socially disapproved behaviors. Two cases illustrate interactions between well-meaning researchers and local authorities. In both, investigations benefited from having laid groundwork for local endorsement of study activities. Research on marijuana smoking in Costa Rica enjoyed strong cooperation from the Ministry of Health, but not so strong from the Ministry of Security because of a fledgling office of Narcotics. Studies of HIV risk among injecting drug users (IDUs) in Valencia, Spain, encountered no problems with police but noted dangers of low drug enforcement. Five principles of preparing for international research may help investigators to anticipate some varieties of contextual obstructions to research outside the United States.

Behavioral Research↗

Foreign transcriptional enhancers in yeast. II. Interplay of the polyomavirus transcriptional enhancer and Saccharomyces cerevisiae promoter elements.

In this paper, to further analyze the function of the polyoma enhancer in Saccharomyces cerevisiae, we use as reporter-genes derivatives of the yeast HIS3 gene flanked by two types of partially deleted promoters: in one, UAS elements are removed by deletion of sequences upstream of nt -80 (pGM3181) in the second both TATA boxes and UAS elements are removed by deletion of sequences upstream of nt -35 (pGM2809). These constructs have been studied both as free plasmids and after integration at the TRP1 chromosomal locus. We find that in general the polyoma holoenhancer (A + B domains) elicits transcription from the physiological HIS3 RNA start sites when the native TATA boxes are present. In contrast, an altered enhancer B-domain from polyoma mutant Py-B78, although active when inserted downstream of the test-gene or when coupled to a pseudopromoter (Ciaramella et al, accompanying manuscript), does not work properly in concert with the native yeast TATA boxes. We describe experiments that suggest an important role for the foreign enhancer in RNA start-site selection in yeast.

Blotting, Northern↗

Interplay between U2 snRNP and 3' splice factor(s) for branch point selection on human beta-globin pre-mRNA.

We investigated the interaction of U2 snRNP with the branch-3' splice site region of three human beta-globin pre-mRNAs carrying nearly complete (BamHI RNA), 24 nt (Avall RNA) and 14 nt (Accl RNA) of exon 2. All supported splicing, but mRNAs yields were respectively 2 and 10 times lower for Avall and Accl RNAs than for BamHI. Analysis of RNase T1-resistant fragments immunoprecipitated by an anti-(U2)RNP antibody at early times of the splicing reaction showed that the protection encompasses both the branch point region and the end of the intron in BamHI and Avall, but essentially only the branch point in Accl RNAs. Later on, this protection becomes less detectable in BamHI, is reinforced in Avall and remains poorly detectable in Accl RNAs. Similar experiments performed at late times with an anti-Sm antibody recognizing all snRNPs showed that the end of the intron is protected in all but BamHI RNAs. These results support the conclusion that U2 snRNP binds to a fully efficient precursor (BamHI RNA) through another factor(s) recognizing the 3' splice site (U5 snRNP and the so-called U2AF protein are likely candidates). Either the absence of an initial contact between U2 snRNP and the factor(s) recognizing the end of the intron (Accl RNA) or the unability of this ternary complex to undergo a conformational change (Avall RNA) could render these severely truncated precursors poor substrates. These different situations have consequences on the branch point selection itself. BamHI and Avall RNAs use three functional branch points at early times, the usual A residue at -37 and two U residues at -17 and -22. Accl RNA uses only one branch point at -37. Later on, all three branch points are used at the same rate in Avall, while the usual one prevails in BamHI RNAs.

Base Sequence↗

The interplay of ubiquitous DNA-binding factors, availability of binding sites in the chromatin, and DNA methylation in the differential regulation of phosphoenolpyruvate carboxykinase gene expression.

We have identified DNA elements in the phosphoenolpyruvate carboxykinase (PEPCK) gene promoter which are bound 'in vivo' by proteins under conditions of basal level gene expression and have evaluated several hypothesis to account for the tissue specific expression of the gene. In vitro DNase I footprinting demonstrated that factors which bind to basal expression elements of the PEPCK promoter, the BSE/CRE and NFI/CCAAT sites, are also present in HTC and XC cells which do not express the PEPCK gene. 'In vivo' DNase I footprinting demonstrated that the BSE/CRE, NFI/CCAAT, and three additional sites are bound by protein in H4IIE cells which express the PEPCK gene but not in the HTC or XC cells. No evidence for a repressor protein or for phased nucleosome binding to the PEPCK promoter in HTC or XC cells could be detected. Genomic sequencing was used to determine if differential methylation of the PEPCK promoter could account for the lack of factor binding in HTC and XC nuclei. None of the 14 cytosine residues in CpG dinucleotides was methylated in H4IIE or rat liver DNA, all were methylated in rat sperm DNA, and 6 were methylated in HTC DNA; including the cytosine at position--90 within the BSE/CRE. Only one cytosine residue, at position--90, was methylated in XC DNA. Treatment of XC cells with 5-azacytidine resulted in loss of methylation at the--90 position yet this was insufficient to allow synthesis of a detectable amount of PEPCK mRNA.

Animals↗

Interplay of an original combination of factors: C/EBP, NFY, HNF3, and HNF1 in the rat aldolase B gene promoter.

The rat aldolase B 5' flanking region (nucleotides - 194 to +41) contains sufficient information for liver-specific expression. A detailed investigation of factors binding to the rat aldolase B 5' flanking region has allowed us to identify three distinct factors that filled different sites of this region (A, B, C). The liver-enriched C/EBP or related factors bind to box C, as demonstrated by the specific interaction with bacterially expressed C/EBP protein. Box B bearing the CCAAT sequence binds the ubiquitous factor NFY. Surprisingly, Box A is able to bind two liver enriched factors, namely HNF1 and HNF3. However, in the context of the intact promoter, as shown by footprinting competition experiments, HNF3 binds solely to this sequence. HNF3, but not HNF1 is a transcriptional activator as demonstrated in the in vitro transcription assay.

Animals↗

Interplay between positive and negative activities that influence the role of Bicoid in transcription.

The Drosophila mophogenetic protein Bicoid (Bcd) can activate transcription in a concentration-dependent manner in embryos. It contains a self-inhibitory domain that can interact with the co-repressor Sin3A. In this report, we study a Bcd mutant, Bcd(A57-61), which has a strengthened self-inhibitory function and is unable to activate the hb-CAT reporter in Drosophila cells, to analyze the role of co-factors in regulating Bcd function. We show that increased concentrations of the co-activator dCBP in cells can switch this protein from its inactive state to an active state on the hb-CAT reporter. The C-terminal portion of Bcd(A57-61) is required to mediate such activity-rescuing function of dCBP. Although capable of binding to DNA in vitro, Bcd(A57-61) is unable to access the hb enhancer element in cells, suggesting that its DNA binding defect is only manifested in a cellular context. Increased concentrations of dCBP restore not only the ability of Bcd(A57-61) to access the hb enhancer element in cells but also the occupancy of the general transcription factors TBP and TFIIB at the reporter promoter. These and other results suggest that an activator can undergo switches between its active and inactive states through sensing the opposing actions of positive and negative co-factors.

Acetyltransferases↗

Interplay of 'induced fit' and preorganization in the ligand induced folding of the aptamer domain of the guanine binding riboswitch.

Riboswitches are highly structured elements in the 5'-untranslated regions (5'-UTRs) of messenger RNA that control gene expression by specifically binding to small metabolite molecules. They consist of an aptamer domain responsible for ligand binding and an expression platform. Ligand binding in the aptamer domain leads to conformational changes in the expression platform that result in transcription termination or abolish ribosome binding. The guanine riboswitch binds with high-specificity to guanine and hypoxanthine and is among the smallest riboswitches described so far. The X-ray-structure of its aptamer domain in complex with guanine/hypoxanthine reveals an intricate RNA-fold consisting of a three-helix junction stabilized by long-range base pairing interactions. We analyzed the conformational transitions of the aptamer domain induced by binding of hypoxanthine using high-resolution NMR-spectroscopy in solution. We found that the long-range base pairing interactions are already present in the free RNA and preorganize its global fold. The ligand binding core region is lacking hydrogen bonding interactions and therefore likely to be unstructured in the absence of ligand. Mg2+-ions are not essential for ligand binding and do not change the structure of the RNA-ligand complex but stabilize the structure at elevated temperatures. We identified a mutant RNA where the long-range base pairing interactions are disrupted in the free form of the RNA but form upon ligand binding in an Mg2+-dependent fashion. The tertiary interaction motif is stable outside the riboswitch context.

5' Untranslated Regions↗

Interplay of Fli-I and FLAP1 for regulation of beta-catenin dependent transcription.

Beta-catenin mediates Wnt/wingless signaling and transcriptional activation by lymphocyte enhancer binding factor 1/T cell factor (LEF1/TCF) proteins with the assistance of multiple coregulators, including positive cofactors like p300/CBP and negative cofactors like HDACs. We previously demonstrated that a developmentally essential protein, Flightless-I (Fli-I), serves as a coactivator for nuclear receptor-mediated transcription. To further understand the action mechanism of Fli-I, we investigated the functional roles of Fli-I and Fli-I leucine rich repeat associated protein 1 (FLAP1) in transcriptional activation by beta-catenin and LEF1/TCF. beta-catenin-dependent transcription was activated by exogenous FLAP1 but inhibited by Fli-I. Reduction of endogenous FLAP1 levels compromised transcriptional activation by LEF1/TCF, beta-catenin and the p160 coactivator GRIP1. FLAP1 interacted directly with beta-catenin, GRIP1 and p300 and enhanced their activity. Furthermore, FLAP1 was strongly synergistic with p300 in supporting transcriptional activation by beta-catenin and LEF1/TCF, but Fli-I disrupted the synergy of FLAP1 with p300 and beta-catenin. Thus the opposing effects of Fli-I and FLAP1 may be a key regulatory mechanism for beta-catenin and LEF1/TCF-mediated transcription and thus for Wnt signaling, and some mutations of Fli-I may result in developmental defects, such as the flightless phenotype of Drosophila, by causing dysregulation of the Wnt/beta-catenin pathway.

Carrier Proteins↗