UFGI publication round-up week 9/18/17
Blood pressure response to metoprolol and chlorthalidone in European and African Americans with hypertension.
Abstract
Despite the availability of many antihypertensive drug classes, half of patients with hypertension have uncontrolled blood pressure (BP). The authors sought to assess the effect of age on BP response in European American and African American patients with hypertension. Clinic BP from the PEAR2 (Pharmacogenomics Evaluation of Antihypertensive Responses 2) study was used to estimate BP responses from baseline following sequential treatment with metoprolol 100 mg twice daily and chlorthalidone 25 mg daily for 8 to 9 weeks each, with a minimum 4-week washout between treatments. BP responses to both drugs were compared in 159 European Americans and 119 African Americans by age with adjustment for baseline BP and sex. European Americans younger than 50 years responded better to metoprolol than chlorthalidone (diastolic BP: -9.6 ± 8.0 vs -5.9 ± 6.8 mm Hg, adjusted P = .003), whereas patients 50 years and older responded better to chlorthalidone than metoprolol (systolic BP: -18.7 ± 13.8 vs -13.6 ± 14.8 mm Hg, adjusted P = .008). African Americans younger than 50 years responded similarly to both drugs, whereas those 50 years and older responded better to chlorthalidone than metoprolol (-17.0 ± 13.2/-9.6 ± 7.5 vs -7.0 ± 18.6/-6.7 ± 9.3 mm Hg, adjusted P<.0001/.008). Therefore, age should be considered when selecting antihypertensive therapy in European and African American populations with hypertension.
Concomitant loss of the glyoxalase system and glycolysis makes the uncultured pathogen “Candidatus Liberibacter asiaticus” an energy scavenger.
Abstract
Methylglyoxal (MG) is a cytotoxic, non-enzymatic byproduct of glycolysis that readily glycates proteins and DNA, resulting in carbonyl stress. Glyoxalase I and II (GloA and GloB) sequentially convert MG into D-lactic acid using glutathione (GSH) as a cofactor. The glyoxalase system is essential for the mitigation of MG-induced carbonyl stress, preventing subsequent cell death, and recycling GSH for maintenance of cellular redox poise. All pathogenic Liberibacters identified to date are uncultured, including “Candidatus Liberibacter asiaticus”, a psyllid endosymbiont and causal agent of the severely damaging citrus disease ‘huanglongbing’. In silico analysis revealed the absence of gloA in “Ca. L. asiaticus” and all other pathogenic Liberibacters. Both gloA and gloB are present in L. crescens, the only Liberibacter that has been cultured. L. crescens GloA was functional in a heterologous host. Marker interruption of gloA in L. crescensappeared to be lethal. Key glycolytic enzymes were either missing or significantly downregulated in “Ca. L. asiaticus”, as compared to (cultured) L. crescens Marker interruption of sut, a sucrose transporter gene in L. crescens, decreased its ability to uptake exogenously supplied sucrose in culture. “Ca. L. asiaticus” lacks a homologous sugar transporter, but has a functional ATP/ADP translocase, enabling it to thrive in both psyllids and in the sugar rich citrus phloem by a) avoiding sucrose uptake; b) avoiding MG generation via glycolysis, and c) directly importing ATP from the host cell. MG detoxification enzymes appear to be predictive of “Candidatus” status for many uncultured pathogenic and environmental bacteria.IMPORTANCE Discovered more than 100 years ago, the glyoxalase system is thought to be present across all domains of life and fundamental to cellular growth and viability. The glyoxalase system protects against carbonyl stress caused by methylglyoxal (MG), a highly reactive, mutagenic and cytotoxic compound that is non-enzymatically formed as a byproduct of glycolysis. The uncultured alphaproteobacterium “Ca. L. asiaticus” is a well-adapted endosymbiont of the Asian citrus psyllid, which transmits the severely damaging citrus disease ‘huanglongbing’ “Ca L. asiaticus” lacks a functional glyoxalase pathway. We report here that, the bacterium is able to thrive in both psyllids and in the sugar rich citrus phloem by a) avoiding sucrose uptake; b) avoiding (significant) MG generation via glycolysis, and c) directly importing ATP from the host cell. We hypothesize that failure to culture “Ca. L. asiaticus” is at least partly due to its dependence on host cells for both ATP and MG detoxification.
Mortality implications of lower DBP with lower achieved systolic pressures in coronary artery disease: long-term mortality results from the INternational VErapamil-trandolapril STudy US cohort.
Abstract
OBJECTIVES:
A goal SBP 120 mmHg or less reduced mortality in high-risk Systolic Blood Pressure Intervention Trial patients; however, mortality implications of concomitant DBP lowering in coronary artery disease (CAD) are uncertain. We examined the relationship between DBP lowering and all-cause mortality with lower achieved SBPs in a large cohort.
METHODS:
We categorized 17 131 hypertensive patients from the INternational VErapamil-trandolapril STudy US cohort, aged at least 50 years with CAD, by mean achieved SBP (<120, 120 to <130, 130 to <140, and ≥140 mmHg) and DBP tertiles (low, middle, and high per SBP category) during active follow-up. Long-term mortality was determined via National Death Index. Multivariable Cox regression was performed to investigate the impact of DBP lowering among all SBP categories and within each SBP category.
RESULTS:
There were 6031 deaths over mean follow-up of 11.6 years (198 352 patient-years). In unadjusted analyses, achieving DBP in the lowest tertile portended greatest mortality risk across all SBP categories. In multivariate analysis, using SBP 120 to less than 130 mmHg, DBP at least 79 mmHg as reference (mortality nadir), achieving DBP in the lowest tertile (DBP < 69 mmHg) was associated with excess mortality risk among those with SBP less than 120 mmHg (adjusted hazard ratio 1.60; 95% confidence interval, 1.33-1.91). However, among those with SBP 120 to less than 140 mmHg, adjusted mortality risk did not differ significantly with low DBPs. Among those with SBP at least 140 mmHg, mortality risk remained high regardless of DBP.
CONCLUSION:
In older CAD patients, the mortality risk related to excess DBP lowering is accentuated in those achieving intensive SBP control less than 120 mmHg, raising concerns about intensive SBP lowering in these patients.
Insights into the impact of CD8+ immune modulation on HIV evolutionary dynamics in distinct anatomical compartments using SIV-infected macaque models of AIDS progression.
Abstract
A thorough understanding of the role of HIV intra-host evolution in AIDS pathogenesis has been limited by the need for longitudinally sampled viral sequences from the vast target space within the host, which are often difficult to obtain from human subjects. CD8+ lymphocyte-depleted macaques infected with simian immunodeficiency virus (SIV) provide an increasingly utilized model of pathogenesis due to similar clinical manifestations as HIV-1 infection and AIDS progression, as well as characteristic rapid disease onset. Comparison of this model with SIV-infected non-CD8+ lymphocyte-depleted macaques also provides a unique opportunity to investigate the role of CD8+ cells in viral evolution and population dynamics throughout the duration of infection. Using several different phylogenetic methods, we analyzed viral gp120 sequences obtained from extensive longitudinal sampling of multiple tissues and enriched leukocyte populations from SIVmac251-infected macaques, with or without CD8+ lymphocyte depletion. SIV evolutionary and selection patterns in non-CD8+ lymphocyte-depleted animals were characterized by sequential population turnover and continual viral adaptation, a scenario readily comparable to intra-host evolutionary patterns during human HIV infection in the absence of antiretroviral therapy. Alternatively, animals that were CD8+ lymphocyte depleted exhibited greater variation in population dynamics among tissues and cell populations over the course of infection. Our findings highlight the major role for CD8+ lymphocytes in prolonging disease progression through continual control of SIV sub-populations from varying anatomical compartments and the potential for greater independent viral evolutionary behavior among these compartments in response to immune modulation.IMPORTANCE Although developments in combined antiretroviral therapy (cART) strategies have successfully prolonged AIDS onset in HIV-1-infected individuals, a functional cure has yet to be found. Improvement of drug interventions for a virus that is able to infect a wide range of tissues and cell types requires a thorough understanding of viral adaptation and infection dynamics within this target milieu. Although difficult to accomplish in the human host, longitudinal sampling of multiple anatomical locations is readily accessible in the SIV-infected macaque models of neuroAIDS. The significance of our research is in identifying the impact of immune modulation, through differing immune selective pressure, on viral evolutionary behavior in a multitude of anatomical compartments. The results provide evidence encouraging the development of a more sophisticated model that considers a network of individual viral subpopulations within the host with differing infection and transmission dynamics, which is necessary for more effective treatment strategies.
A bifunctional catalase-peroxidase, MakatG1, contributes to virulence of Metarhizium acridum by overcoming oxidative stress on the host insect cuticle.
Abstract
Microbial pathogens are exposed to damaging reactive oxygen species (ROS) produced from a variety of sources including chemical reactions due to exposure to stress (UV, heat) or by hosts as a defense response. Here we demonstrate that a bifunctional catalase-peroxidase, MakatG1, in the locust-specific fungal pathogen, Metarhizium acridum, functions as a ROS detoxification mechanism during host cuticle penetration. MakatG1 expression was highly induced during on-cuticle appressoria development as compared to vegetative (mycelia) growth or during in vivo growth in the insect hemocoel. A MakatG1 deletion mutant strain (ΔMakatG1) showed decreased catalase and peroxidase activities and significantly increased susceptibility to oxidative (H2 O2 and menadione) and UV stress as compared to wild type and complemented strains. Insect bioassays revealed significantly reduced virulence of the ΔMakatG1 mutant when topically inoculated, but no impairment when the insect cuticle was bypassed. Germination and appressoria formation rates for the ΔMakatG1 mutant were decreased on locust wings and quinone/phenolic compounds derived from locust wings, but were not affected on plastic surfaces compared with the wild type strain. These data indicate that MakatG1 plays a pivotal role in penetration, reacting to and detoxifying specific cuticular compounds present on the host cuticle during the early stages of fungal infection. This article is protected by copyright. All rights reserved.
Circuitry linking the global Csr and σE-dependent cell envelope stress response systems.
Abstract
CsrA of Escherichia coli is an RNA-binding protein that globally regulates a wide variety of cellular processes and behaviors including carbon metabolism, motility, biofilm formation, and the stringent response. CsrB and CsrC are sRNAs that sequester CsrA, thereby preventing CsrA-mRNA interaction. RpoE (σE) is the extracytoplasmic stress response sigma factor of E. coli Previous RNA-seq studies identified rpoE mRNA as a CsrA target. Here we explored the regulation of rpoE by CsrA and found that CsrA represses rpoE translation. Gel mobility shift, footprint and toeprint studies identified three CsrA binding sites in the rpoE leader transcript, one of which overlaps the rpoE Shine-Dalgarno (SD) sequence, while another overlaps the rpoE translation initiation codon. Coupled in vitro transcription-translation experiments showed that CsrA represses rpoE translation by binding to these sites. We further demonstrate that σE indirectly activates transcription of csrB and csrC, leading to increased sequestration of CsrA such that repression of rpoE by CsrA is reduced. We propose that the Csr system fine-tunes the σE-dependent cell envelope stress response. We also identified a 51 amino acid coding sequence whose stop codon overlaps the rpoE start codon, and demonstrate that rpoE is translationally coupled with this upstream open reading frame (ORF51). Loss of coupling reduces rpoE translation by more than 50%. Identification of a translationally coupled ORF upstream of rpoE suggests that this previously unannotated protein may participate in the cell envelope stress response. In keeping with existing nomenclature, we name ORF51 as rseD, resulting in an operon arrangement of rseD-rpoE-rseA-rseB-rseCIMPORTANCE CsrA posttranscriptionally represses genes required for bacterial stress responses, including the stringent response, catabolite repression, and the RpoS (σS)-mediated general stress response. We show that CsrA represses translation of rpoE, encoding the extracytoplasmic stress response sigma factor and that σE indirectly activates transcription of csrB and csrC, resulting in reciprocal regulation of these two global regulatory systems. These findings suggest that extracytoplasmic stress leads to derepression of rpoE translation by CsrA, and CsrA-mediated repression helps to reset RpoE abundance to pre-stress levels once envelope damage is repaired. The discovery of an ORF, RseD, translationally coupled with rpoE adds further complexity to translational control of rpoE.
Proteoliposome-based full-length ZnT8 self-antigen for type 1 diabetes diagnosis on a plasmonic platform.
Abstract
Identified as a major biomarker for type 1 diabetes (T1D) diagnosis, zinc transporter 8 autoantibody (ZnT8A) has shown promise for staging disease risk and disease diagnosis. However, existing assays for ZnT8 autoantibody (ZnT8A) are limited to detection by soluble domains of ZnT8, owing to difficulties in maintaining proper folding of a full-length ZnT8 protein outside its native membrane environment. Through a combined bioengineering and nanotechnology approach, we have developed a proteoliposome-based full-length ZnT8 self-antigen (full-length ZnT8 proteoliposomes; PLR-ZnT8) for efficient detection of ZnT8A on a plasmonic gold chip (pGOLD). The protective lipid matrix of proteoliposomes improved the proper folding and structural stability of full-length ZnT8, helping PLR-ZnT8 immobilized on pGOLD (PLR-ZnT8/pGOLD) achieve high-affinity capture of ZnT8A from T1D sera. Our PLR-ZnT8/pGOLD exhibited efficient ZnT8A detection for T1D diagnosis with ∼76% sensitivity and ∼97% specificity (n = 307), superior to assays based on detergent-solubilized full-length ZnT8 and the C-terminal domain of ZnT8. Multiplexed assays using pGOLD were also developed for simultaneous detection of ZnT8A, islet antigen 2 autoantibody, and glutamic acid decarboxylase autoantibody for diagnosing T1D.
Recognition-then-Reaction Enables Site-Selective Bioconjugation to Proteins on Live-Cell Surfaces.
Abstract
Site-selective protein modification is a key step in facilitating protein functionalization and manipulation. To accomplish this, genetically engineered proteins were previously required, but the procedure was laborious, complex, and technically challenging. Herein we report the development of aptamer-based recognition-then-reaction to guide site-selective protein/DNA conjugation in a single step with outstanding selectivity and efficiency. As models, several proteins, including human thrombin, PDGF-BB, Avidin, and His-tagged recombinant protein, were studied, and the results showed excellent selectivity under mild reaction conditions. Taking advantage of aptamers as recognition elements with extraordinary selectivity and affinity, this simple preparation method can tag a protein in a complex milieu. Thus, with the aptamer obtained from cell-SELEX, real-time modification of live-cell membrane proteins can be achieved in one step without any pre-treatment.
Heterologous Expression of Pteris vittata Arsenite Antiporter PvACR3;1 Reduces Arsenic Accumulation in Plant Shoots.
Abstract
Arsenic (As) is a toxic carcinogen so it is crucial to decrease As accumulation in crops to reduce its risk to human health. Arsenite (AsIII) antiporter ACR3 protein is critical for As metabolism in organisms, but it is lost in flowering plants. Here, a novel ACR3 gene from As-hyperaccumulator Pteris vittata, PvACR3;1, was cloned and expressed in Saccharomyces cerevisiae (yeast), Arabidopsis thaliana (model plant), and Nicotiana tabacum (tobacco). Yeast experiments showed that PvACR3;1 functioned as an AsIII-antiporter to mediate AsIII efflux to an external medium. At 5 μM AsIII, PvACR3;1 transgenic Arabidopsis accumulated 14-29% higher As in the roots and 55-61% lower As in the shoots compared to WT control, showing lower As translocation. Besides, transgenic tobacco under 5 μM AsIII or AsV also showed similar results, indicating that expressing PvACR3;1 gene increased As retention in plant roots. Moreover, observation of PvACR3;1-green fluorescent protein fusions in transgenic Arabidopsis showed that PvACR3;1 protein localized to the vacuolar membrane, indicating that PvACR3;1 mediated AsIII sequestration into vacuoles, consistent with increased root As. In addition, soil experiments showed ∼22% lower As in the shoots of transgenic tobacco than control. Thus, our study provides a potential strategy to limit As accumulation in plant shoots, representing the first report to decrease As translocation by sequestrating AsIII into vacuoles, shedding light on engineering low-As crops to improve food safety.
Aptamer/AuNP Biosensor for Colorimetric Profiling of Exosomal Proteins.
Abstract
Exosomes constitute an emerging biomarker for cancer diagnosis because they carry multiple proteins that reflect the origins of parent cells. Assessing exosome surface proteins provides a powerful means of identifying a combination of biomarkers for cancer diagnosis. We report a sensor platform that profiles exosome surface proteins in minutes by the naked eye. The sensor consists of a gold nanoparticle (AuNP) complexed with a panel of aptamers. The complexation of aptamers with AuNPs protects the nanoparticles from aggregating in a high-salt solution. In the presence of exosomes, the non-specific and weaker binding between aptamers and the AuNP is broken, and the specific and stronger binding between exosome surface protein and the aptamer displaces aptamers from the AuNP surface and results in AuNP aggregation. This aggregation results in a color change and generates patterns for the identification of multiple proteins on the exosome surface.
Antibacterial Resistance in Ureaplasma Species and Mycoplasma hominis Isolates from Urine Cultures in College-Aged Females.
Abstract
Urinary tract infections (UTIs) affect nearly 20% of women age 15 to 29 and account for an estimated $3.5 billion in costs. Antibiotic resistance prolongs UTI treatment, and resistance profiles vary regionally. This regional variation is an important consideration in guiding empirical treatment selection. Regional studies in the United States have identified tetracycline resistance in over one-third of Ureaplasma species isolates, but no studies have evaluated antibiotic resistance levels in college-aged women with a first-time UTI. We tested a panel of antibiotics and determined the MICs of Ureaplasma species (60 U. parvum and 13 U. urealyticum) and 10 Mycoplasma hominis isolates obtained from urine from college-aged women with a first-time UTI. Low antibiotic resistance was found in this population of women with a first-time UTI. All M. hominis and U. urealyticum isolates were sensitive. However, two U. parvum isolates were resistant, with one to levofloxacin (MIC, 4 μg/ml) and one to tetracycline (MIC, 8 μg/ml). For the Ureaplasma spp., the MIC90s were highest against gentamicin (21 μg/ml) and lowest against doxycycline (0.25 μg/ml). In a comparison of MIC levels between Ureaplasmaspp., U. urealyticum had significantly higher MICs against each antibiotic except doxycycline. For the resistant isolates, the genetic mechanisms of resistance were determined. PCR amplification identified tetM to be present in the tetracycline-resistant isolate and an S83W mutation within the parC gene of the quinolone-resistant isolate. To our knowledge, this study is the first to provide molecular and phenotypic evidence of the S83W parC mutation conferring levofloxacin resistance in U. parvum isolated from a patient in the United States.
A viral microRNA downregulates metastasis suppressor CD82 and induces cell invasion and angiogenesis by activating the c-Met signaling.
Abstract
Kaposi’s sarcoma (KS) as the most common AIDS-associated malignancy is etiologically caused by KS-associated herpesvirus (KSHV). KS is a highly disseminated and vascularized tumor. KSHV encodes 12 pre-microRNAs that yield 25 mature microRNAs (miRNAs), but their roles in KSHV-induced tumor metastasis and angiogenesis remain largely unclear. KSHV-encoded miR-K12-6 (miR-K6) can generate two mature miRNAs, miR-K6-5p and miR-K6-3p. Recently, we have shown that miR-K6-3p induced cell migration and angiogenesis via directly targeting SH3 domain binding glutamate-rich protein (SH3BGR). Here, by using mass spectrometry, bioinformatics analysis and luciferase reporter assay, we showed that miR-K6-5p directly targeted the coding sequence of CD82 molecule (CD82), a metastasis suppressor. Ectopic expression of miR-K6-5p specifically inhibited the expression of endogenous CD82 and strongly promoted endothelial cells invasion and angiogenesis. Overexpression of CD82 significantly inhibited cell invasion and angiogenesis induced by miR-K6-5p. Mechanistically, CD82 directly interacted with c-Met to inhibit its activation. MiR-K6-5p directly repressed CD82, relieving its inhibition on c-Met activation and inducing cell invasion and angiogenesis. Lack of miR-K6 abrogated KSHV suppression of CD82 resulting in compromised KSHV activation of c-Met pathway, and KSHV induction of cell invasion and angiogenesis. In conclusion, our data show that by reducing CD82, KSHV miR-K6-5p expedites cell invasion and angiogenesis by activating the c-Met pathway. Our findings illustrate that KSHV miRNAs may be critical for the dissemination and angiogenesis of KSHV-induced malignant tumors.
NOTE: These abstracts were retrieved from the U.S. National Library of Medicine website managed in collaboration with the U.S. National Library of Medicine