bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mycoplasma genitalium Nonadherent Phase Variants Arise by Multiple Mechanisms and Escape Antibody-Dependent Growth Inhibition
Authors: Burgos Raul , Wood Gwendolyn E. , Iverson-Cabral Stefanie L. , Totten Patricia A. 
Published: January 2018

ABSTRACT

Antigenic variation of the immunodominant MgpB and MgpC proteins has been suggested to be a mechanism of immune evasion of the human pathogen
Mycoplasma genitalium
, a cause of several reproductive tract disease syndromes. Phase variation resulting in the loss of adherence has also been documented, but the molecular mechanisms underlying this process and its role in pathogenesis are still poorly understood. In this study, we isolated and characterized 40 spontaneous, nonadherent phase variants from
in vitro
-passaged
M. genitalium
cultures. In all cases, nonadherence was associated with the loss of MgpBC protein expression, attributable to sequence changes in the
mgpBC
expression site. Phase variants were grouped into seven classes on the basis of the nature of the mutation. Consistent with the established role of RecA in phase variation, 31 (79.5%) variants arose via recombination with MgPa repeat regions that contain
mgpBC
variable sequences. The remaining mutants arose via nonsense or frameshift mutations. As expected, revertants were obtained for phase variants that were predicted to be reversible but not for those that arose via an irreversible mechanism. Furthermore, phase variants were enriched in
M. genitalium
cultures exposed to antibodies reacting to the extracellular, conserved C terminus of MgpB but not in cultures exposed to antibodies reacting to an intracellular domain of MgpB or the cytoplasmic HU protein. Genetic characterization of the antibody-selected phase variants confirmed that they arose via reversible and irreversible recombination and point mutations within
mgpBC
. These phase variants resisted antibody-mediated growth inhibition, suggesting that phase variation promotes immune evasion.
The Ancient Link between G-Protein-Coupled Receptors and C-Terminal Phospholipid Kinase Domains
Authors: van den Hoogen D. Johan , Meijer Harold J. G. , Seidl Michael F. , Govers Francine 
Published: January 2018

ABSTRACT
Sensing external signals and transducing these into intracellular responses requires a molecular signaling system that is crucial for every living organism. Two important eukaryotic signal transduction pathways that are often interlinked are G-protein signaling and phospholipid signaling. Heterotrimeric G-protein subunits activated by G-protein-coupled receptors (GPCRs) are typical stimulators of phospholipid signaling enzymes such as phosphatidylinositol phosphate kinases (PIPKs) or phospholipase C (PLC). However, a direct connection between the two pathways likely exists in oomycetes and slime molds, as they possess a unique class of GPCRs that have a PIPK as an accessory domain. In principle, these so-called GPCR-PIPKs have the capacity of perceiving an external signal (via the GPCR domain) that, via PIPK, directly activates downstream phospholipid signaling. Here we reveal the sporadic occurrence of GPCR-PIPKs in all eukaryotic supergroups, except for plants. Notably, all species having GPCR-PIPKs are unicellular microorganisms that favor aquatic environments. Phylogenetic analysis revealed that GPCR-PIPKs are likely ancestral to eukaryotes and significantly expanded in the last common ancestor of oomycetes. In addition to GPCR-PIPKs, we identified five hitherto-unknown classes of GPCRs with accessory domains, four of which are universal players in signal transduction. Similarly to GPCR-PIPKs, this enables a direct coupling between extracellular sensing and downstream signaling. Overall, our findings point to an ancestral signaling system in eukaryotes where GPCR-mediated sensing is directly linked to downstream responses.

IMPORTANCE
G-protein-coupled receptors (GPCRs) are central sensors that activate eukaryotic signaling and are the primary targets of human drugs. In this report, we provide evidence for the widespread though limited presence of a novel class of GPCRs in a variety of unicellular eukaryotes. These include free-living organisms and organisms that are pathogenic for plants, animals, and humans. The novel GPCRs have a C-terminal phospholipid kinase domain, pointing to a direct link between sensing external signals via GPCRs and downstream intracellular phospholipid signaling. Genes encoding these receptors were likely present in the last common eukaryotic ancestor and were lost during the evolution of higher eukaryotes. We further describe five other types of GPCRs with a catalytic accessory domain, the so-called GPCR-bigrams, four of which may potentially have a role in signaling. These findings shed new light onto signal transduction in microorganisms and provide evidence for alternative eukaryotic signaling pathways.
A Phosphorylation Switch on Lon Protease Regulates Bacterial Type III Secretion System in Host
Authors: Zhou Xiaofeng , Teper Doron , Andrade Maxuel O. , Zhang Tong , Chen Sixue , Song Wen-Yuan , Wang Nian 
Published: January 2018

ABSTRACTMost pathogenic bacteria deliver virulence factors into host cytosol through type III secretion systems (T3SS) to perturb host immune responses. The expression of T3SS is often repressed in rich medium but is specifically induced in the host environment. The molecular mechanisms underlying host-specific induction of T3SS expression is not completely understood. Here we demonstrate inXanthomonas citrithat host-induced phosphorylation of the ATP-dependent protease Lon stabilizes HrpG, the master regulator of T3SS, conferring bacterial virulence. Ser/Thr/Tyr phosphoproteome analysis revealed that phosphorylation of Lon at serine 654 occurs in the citrus host. In rich medium, Lon represses T3SS by degradation of HrpG via recognition of its N terminus. Genetic and biochemical data indicate that phosphorylation at serine 654 deactivates Lon proteolytic activity and attenuates HrpG proteolysis. Substitution of alanine for Lon serine 654 resulted in repression of T3SS gene expression in the citrus host through robust degradation of HrpG and reduced bacterial virulence. Our work reveals a novel mechanism for distinct regulation of bacterial T3SS in different environments. Additionally, our data provide new insight into the role of protein posttranslational modification in the regulation of bacterial virulence.IMPORTANCEType III secretion systems (T3SS) are an essential virulence trait of many bacterial pathogens because of their indispensable role in the delivery of virulence factors. However, expression of T3SS in the noninfection stage is energy consuming. Here, we established a model to explain the differential regulation of T3SS in host and nonhost environments. WhenXanthomonascells are grown in rich medium, the T3SS regulator HrpG is targeted by Lon protease for proteolysis. The degradation of HrpG leads to downregulated expression of HrpX and thehrp/hrcgenes. WhenXanthomonascells infect the host, specific plant stimuli can be perceived and induce Lon phosphorylation at serine 654. Phosphorylation on Lon attenuates its proteolytic activity and protects HrpG from degradation. Consequently, enhanced stability of HrpG activates HrpX and turns on bacterial T3SS in the host. Our work provides a novel molecular mechanism underlying host-dependent activation of bacterial T3SS.
Staphylococcus aureus
Responds to the Central Metabolite Pyruvate To Regulate Virulence
Authors: Harper Lamia , Balasubramanian Divya , Ohneck Elizabeth A. , Sause William E. , Chapman Jessica , Mejia-Sosa Bryan , Lhakhang Tenzin , Heguy Adriana , Tsirigos Aristotelis , Ueberheide Beatrix , Boyd Jeffrey M. , Lun Desmond S. , Torres Victor J. 
Published: January 2018

ABSTRACT

Staphylococcus aureus
is a versatile bacterial pathogen that can cause significant disease burden and mortality. Like other pathogens,
S. aureus
must adapt to its environment to produce virulence factors to survive the immune responses evoked by infection. Despite the importance of environmental signals for
S. aureus
pathogenicity, only a limited number of these signals have been investigated in detail for their ability to modulate virulence. Here we show that pyruvate, a central metabolite, causes alterations in the overall metabolic flux of
S. aureus
and enhances its pathogenicity. We demonstrate that pyruvate induces the production of virulence factors such as the pore-forming leucocidins and that this induction results in increased virulence of community-acquired methicillin-resistant
S. aureus
(CA-MRSA) clone USA300. Specifically, we show that an efficient “pyruvate response” requires the activation of
S. aureus
master regulators AgrAC and SaeRS as well as the ArlRS two-component system. Altogether, our report further establishes a strong relationship between metabolism and virulence and identifies pyruvate as a novel regulatory signal for the coordination of the
S. aureus
virulon through intricate regulatory networks.

IMPORTANCE
Delineation of the influence of host-derived small molecules on the makeup of human pathogens is a growing field in understanding host-pathogen interactions.
S. aureus
is a prominent pathogen that colonizes up to one-third of the human population and can cause serious infections that result in mortality in ~15% of cases. Here, we show that pyruvate, a key nutrient and central metabolite, causes global changes to the metabolic flux of
S. aureus
and activates regulatory networks that allow significant increases in the production of leucocidins. These and other virulence factors are critical for
S. aureus
to infect diverse host niches, initiate infections, and effectively subvert host immune responses. Understanding how environmental signals, particularly ones that are essential to and prominent in the human host, affect virulence will allow us to better understand pathogenicity and consider more-targeted approaches to tackling the current
S. aureus
epidemic.
A cross-sectional analysis of the relationship between diabetes and health access barriers in an urban First Nations population in Canada
Authors: Beckett Michael , Firestone Michelle A , McKnight Constance D , Smylie Janet , Rotondi Michael A 
Published: January 2018

ObjectiveThis study explores the relationship between health access barriers and diabetes in an urban First Nations population in Canada.DesignData from a self-identified urban First Nations population were collected using respondent-driven sampling (RDS). As no clear approach for regression modelling of RDS data is available, two logistic regression modelling approaches, including survey-based logistic and generalised linear mixed models, were used to explore the relationship between diabetes and health barriers of interest, including access to healthcare, food, housing and socioeconomic factors.SettingHamilton, Ontario, Canada.ParticipantsThis cross-sectional study used data collected from the Our Health Counts study, in partnership with the De dwa da dehs nye>s Aboriginal Health Centre, which recruited 554 First Nations adults living in Hamilton using RDS.ResultsAfter adjusting for covariates, multivariable regression techniques showed a statistically significant relationship between a self-reported diagnosis of diabetes and a lack of culturally appropriate care among urban First Nations peoples (OR: 12.70, 95% CI 2.52 to 57.91). There was also a trend towards a relationship between diabetes and not having a doctor available in the area, feeling that healthcare provided was inadequate and a lack of available healthcare services in the area.ConclusionsUrban First Nations peoples who felt the health service they received was not culturally appropriate were more likely to have diabetes, compared with those who did not feel the service they received was culturally inappropriate. Establishing more healthcare services that integrate First Nations cultures and traditions could improve access to care and the course of treatment for urban First Nations peoples living with diabetes.
Developing a dementia-specific preference-­based quality of life measure (AD-5D) in Australia: a valuation study protocol
Authors: Comans Tracy A , Nguyen Kim-Huong , Mulhern Brendan , Corlis Megan , Li Li , Welch Alyssa , Kurrle Susan E , Rowen Donna , Moyle Wendy , Kularatna Sanjeewa , Ratcliffe Julie 
Published: January 2018

IntroductionGeneric instruments for assessing health-related quality of life may lack the sensitivity to detect changes in health specific to certain conditions, such as dementia. The Quality of Life in Alzheimer’s Disease (QOL-AD) is a widely used and well-validated condition-specific instrument for assessing health-related quality of life for people living with dementia, but it does not enable the calculation of quality-adjusted life years, the basis of cost utility analysis. This study will generate a preference-based scoring algorithm for a health state classification system -the Alzheimer’s Disease Five Dimensions (AD-5D) derived from the QOL-AD.Methods and analysisDiscrete choice experiments with duration (DCETTO) and best–worst scaling health state valuation tasks will be administered to a representative sample of 2000 members of the Australian general population via an online survey and to 250 dementia dyads (250 people with dementia and their carers) via face-to-face interview. A multinomial (conditional) logistic framework will be used to analyse responses and produce the utility algorithm for the AD-5D.Ethics and disseminationThe algorithms developed will enable prospective and retrospective economic evaluation of any treatment or intervention targeting people with dementia where the QOL-AD has been administered and will be available online. Results will be disseminated through journals that publish health economics articles and through professional conferences. This study has ethical approval.
Screening for chronic kidney disease in a community-based diabetes cohort in rural Guatemala: a cross-sectional study
Authors: Flood David , Garcia Pablo , Douglas Kate , Hawkins Jessica , Rohloff Peter 
Published: January 2018

ObjectiveScreening is a key strategy to address the rising burden of chronic kidney disease (CKD) in low-income and middle-income countries. However, there are few reports regarding the implementation of screening programmes in resource-limited settings. The objectives of this study are to (1) to share programmatic experiences implementing CKD screening in a rural, resource-limited setting and (2) to assess the burden of renal disease in a community-based diabetes programme in rural Guatemala.DesignCross-sectional assessment of glomerular filtration rate (GFR) and urine albumin.SettingCentral Highlands of Guatemala.ParticipantsWe enrolled 144 adults with type 2 diabetes in a community-based CKD screening activity carried out by the sponsoring institution.Outcome measuresPrevalence of renal disease and risk of CKD progression using Kidney Disease: Improving Global Outcomes definitions and classifications.ResultsWe found that 57% of the sample met GFR and/or albuminuria criteria suggestive of CKD. Over half of the sample had moderate or greater increased risk for CKD progression, including nearly 20% who were classified as high or very high risk. Hypertension was common in the sample (42%), and glycaemic control was suboptimal (mean haemoglobin A1c 9.4%±2.5% at programme enrolment and 8.6%±2.3% at time of CKD screening).ConclusionsThe high burden of renal disease in our patient sample suggests an imperative to better understand the burden and risk factors of CKD in Guatemala. The implementation details we share reveal the tension between evidence-based CKD screening versus screening that can feasibly be delivered in resource-limited global settings.
An approach to the instanton effect in B system
Authors: Kitazawa Noriaki , Sakai Yuki 
Published: January 2018

We discuss the constraint on the size of QCD instanton effects in low-energy effective theory. Among various instanton effects in meson mass spectrum and dynamics, we concentrate on the instanton-induced masses of light quarks. The famous instanton-induced six-quark interaction, so-called ’t Hooft vertex, could give nonperturbative quantum corrections to light quark masses. Many works have already been achieved to constrain the mass corrections in light meson system, or the system of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], and now we know for a fact that the instanton-induced mass of up-quark is too small to realize the solution of the strong CP problem by vanishing current mass of up-quark. In this work, we give a constraint on the instanton-induced mass correction to light quarks from the mass spectrum of heavy mesons, [Formula: see text], [Formula: see text], [Formula: see text] and their antiparticles. To accomplish this, the complete second-order chiral symmetry breaking terms are identified in heavy meson effective theory. We find that the strength of the constraint from heavy meson masses is at the same level of that from light mesons, and it would be made even stronger by more precise data from future [Formula: see text] factories and lattice calculations.
Small-Molecule Activators of Protein Phosphatase 2A for the Treatment of Castration-Resistant Prostate Cancer
Authors: McClinch Kimberly , Avelar Rita A. , Callejas David , Izadmehr Sudeh , Wiredja Danica , Perl Abbey , Sangodkar Jaya , Kastrinsky David B. , Schlatzer Daniela , Cooper Maxwell , Kiselar Janna , Stachnik Agnes , Yao Shen , Hoon Divya , McQuaid Daniel , Zaware Nilesh , Gong Yixuan , Brautigan David L. , Plymate Stephen R. , Sprenger Cynthia C.T. , Oh William K. , Levine Alice C. , Kirschenbaum Alexander , Sfakianos John P. , Sears Rosalie , DiFeo Analisa , Ioannou Yiannis , Ohlmeyer Michael , Narla Goutham , Galsky Matthew D. 
Published: January 2018

Abstract
Primary prostate cancer is generally treatable by androgen deprivation therapy, however, later recurrences of castrate-resistant prostate cancer (CRPC) that are more difficult to treat nearly always occur due to aberrant reactivation of the androgen receptor (AR). In this study, we report that CRPC cells are particularly sensitive to the growth-inhibitory effects of reengineered tricyclic sulfonamides, a class of molecules that activate the protein phosphatase PP2A, which inhibits multiple oncogenic signaling pathways. Treatment of CRPC cells with small-molecule activators of PP2A (SMAP) in vitro decreased cellular viability and clonogenicity and induced apoptosis. SMAP treatment also induced an array of significant changes in the phosphoproteome, including most notably dephosphorylation of full-length and truncated isoforms of the AR and downregulation of its regulatory kinases in a dose-dependent and time-dependent manner. In murine xenograft models of human CRPC, the potent compound SMAP-2 exhibited efficacy comparable with enzalutamide in inhibiting tumor formation. Overall, our results provide a preclinical proof of concept for the efficacy of SMAP in AR degradation and CRPC treatment.
Significance: A novel class of small-molecule activators of the tumor suppressor PP2A, a serine/threonine phosphatase that inhibits many oncogenic signaling pathways, is shown to deregulate the phosphoproteome and to destabilize the androgen receptor in advanced prostate cancer. Cancer Res; 78(8); 2065–80. ©2018 AACR.
Selective mTORC2 Inhibitor Therapeutically Blocks Breast Cancer Cell Growth and Survival
Authors: Werfel Thomas A. , Wang Shan , Jackson Meredith A. , Kavanaugh Taylor E. , Joly Meghan Morrison , Lee Linus H. , Hicks Donna J. , Sanchez Violeta , Ericsson Paula Gonzalez , Kilchrist Kameron V. , Dimobi Somtochukwu C. , Sarett Samantha M. , Brantley-Sieders Dana M. , Cook Rebecca S. , Duvall Craig L. 
Published: January 2018

Abstract
Small-molecule inhibitors of the mTORC2 kinase (torkinibs) have shown efficacy in early clinical trials. However, the torkinibs under study also inhibit the other mTOR-containing complex mTORC1. While mTORC1/mTORC2 combined inhibition may be beneficial in cancer cells, recent reports describe compensatory cell survival upon mTORC1 inhibition due to loss of negative feedback on PI3K, increased autophagy, and increased macropinocytosis. Genetic models suggest that selective mTORC2 inhibition would be effective in breast cancers, but the lack of selective small-molecule inhibitors of mTORC2 have precluded testing of this hypothesis to date. Here we report the engineering of a nanoparticle-based RNAi therapeutic that can effectively silence the mTORC2 obligate cofactor Rictor. Nanoparticle-based Rictor ablation in HER2-amplified breast tumors was achieved following intratumoral and intravenous delivery, decreasing Akt phosphorylation and increasing tumor cell killing. Selective mTORC2 inhibition in vivo, combined with the HER2 inhibitor lapatinib, decreased the growth of HER2-amplified breast cancers to a greater extent than either agent alone, suggesting that mTORC2 promotes lapatinib resistance, but is overcome by mTORC2 inhibition. Importantly, selective mTORC2 inhibition was effective in a triple-negative breast cancer (TNBC) model, decreasing Akt phosphorylation and tumor growth, consistent with our findings that RICTOR mRNA correlates with worse outcome in patients with basal-like TNBC. Together, our results offer preclinical validation of a novel RNAi delivery platform for therapeutic gene ablation in breast cancer, and they show that mTORC2-selective targeting is feasible and efficacious in this disease setting.
Significance: This study describes a nanomedicine to effectively inhibit the growth regulatory kinase mTORC2 in a preclinical model of breast cancer, targeting an important pathogenic enzyme in that setting that has been undruggable to date. Cancer Res; 78(7); 1845–58. ©2018 AACR.
Carcinogen Exposure among Canadian Tobacco Users: Changes in NNK Exposure from 2007–2009 through 2012–2013
Authors: Czoli Christine D. , Hammond David 
Published: January 2018

Abstract
Background: Tobacco-specific nitrosamines (TSNAs) are a class of carcinogens found in tobacco products, whose levels can vary considerably depending on tobacco blends and manufacturing processes. The current study examined whether recent increases in levels of the TSNA NNK [4-(methylnitrosamino-1-(3-pyridyl)-1-butanone] in Canadian cigarettes translated into differences in exposure among Canadian tobacco users.
Methods: Nationally representative data from the Canadian Health Measures Survey (CHMS) were used to measure levels of total urinary NNAL [4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol], a metabolite of the TSNA NNK, among tobacco users. Data from CHMS Cycle 3 (2012–13) were used to examine NNAL, and linear regression was used to examine predictors. Data from CHMS Cycle 1 (2007–09) and Cycle 3 (2012–13) were used to examine changes in NNAL over time.
Results: From 2007–2009 through 2012–2013, levels of creatinine-corrected NNAL increased by 64% (P &lt; 0.0001). Levels of NNAL in 2012–2013 were higher among older respondents (P = 0.04), among females (P = 0.03), among respondents identifying as “white” and “Aboriginal” (P &lt; 0.0001), and among those with greater daily cigarette consumption (P &lt; 0.001), as well as greater levels of urinary free cotinine (P &lt; 0.0001) and urinary creatinine (P &lt; 0.0001).
Conclusions: The findings indicate that exposure to the TSNA NNK among Canadian tobacco users has increased considerably from 2007–2009 through 2012–2013, in parallel to changes in TSNA levels in Canadian cigarettes. In the absence of epidemiologic data, it is unclear whether this change translates into increased risk.
Impact: The study findings have potential implications for tobacco manufacturers, who bear a responsibility to reduce levels of tobacco carcinogens to the full extent possible. Cancer Epidemiol Biomarkers Prev; 27(3); 262–7. ©2018 AACR.