Ancient and modern mechanisms compete in progesterone receptor activation.

The progesterone receptor (PR) belongs to the steroid receptor family of ligand-regulated transcription factors, controlling genes important for development, metabolism, and reproduction. Understanding how diverse ligands bind and modulate PR activity will illuminate the design of ligands that control PR-driven signaling pathways. Here, we use molecular dynamics simulations to investigate how PR dynamics are altered by functionally diverse ligands. Using a library of 33 steroidal ligands that range from inactive to EC50 < 0.1 nM, we reveal an unexpected evolutionary basis for the wide gamut of activation. While other oxosteroid receptors employ an evolutionarily conserved mechanism dependent on a hydrogen bond between the receptor and ligand, extant PR has evolved a preference for activation that is not reliant on this polar interaction. We demonstrate that potent ligands utilize the modern PR mechanism while weaker ligands coopt the defunct ancestral mechanism by forming hydrogen bonds with Asn719. Based on their structures and dynamic signatures, ligands partition into four classes (inactive, weak, moderate and high potency) that interact distinctly with the PR binding pocket. Further, we use luciferase reporter assays and PR mutants to probe the roles of pocket residues in mediating distinct PR mechanisms. This combination of MD simulations and in vitro studies provide insight into how the evolutionary history of PR shapes its response to diverse ligands.

Simulations reveal the flexible domain architecture of full-length nuclear receptor complexes.

Nuclear receptors are multidomain transcription factors whose full-length quaternary architecture is poorly described and understood. Most nuclear receptors bind DNA as heterodimers or homodimers, which could encompass a variety of arrangements of the individual domains. Only a handful of experimental structures currently exist describing these architectures. Given that domain interactions and protein-DNA interactions within transcriptional complexes are tightly linked to function, understanding the arrangement of nuclear receptor domains on DNA is of utmost importance. Here, we employ modeling and molecular dynamics (MD) simulations to describe the structure of the full-length farnesoid X receptor (FXR) and retinoid X receptor alpha (RXR) heterodimer bound to DNA. Using over 100 microseconds of atomistic MD simulations, we characterize the dynamic behavior of eight FXR-RXR-DNA complexes, showing that these complexes support a range of quaternary architectures. We reveal the role of DNA binding and the hinge linkers in diversifying domain arrangements, roles that have been hard to appreciate previously due to experimental limitations in studying the flexible hinge. These studies provide a much-needed framework that will enable the field to obtain a complete understanding of nuclear receptor quaternary architectures.

Illuminating ligand-induced dynamics in nuclear receptors through MD simulations.

Nuclear receptors (NRs) regulate gene expression in critical physiological processes, with their functionality finely tuned by ligand-induced conformational changes. While NRs may sometimes undergo significant conformational motions in response to ligand-binding, these effects are more commonly subtle and challenging to study by traditional structural or biophysical methods. Molecular dynamics (MD) simulations are a powerful tool to bridge the gap between static protein-ligand structures and dynamical changes that govern NR function. Here, we summarize a handful of recent studies that apply MD simulations to study NRs. We present diverse methodologies for analyzing simulation data with a detailed examination of the information each method can yield. By delving into the strengths, limitations and unique contributions of these tools, this review provides guidance for extracting meaningful data from MD simulations to advance the goal of understanding the intricate mechanisms by which ligands orchestrate a range of functional outcomes in NRs.

How nuclear receptors transition between active and inactive forms: An energetic perspective.

Nuclear receptors regulate transcriptional programs in response to the binding of natural and synthetic ligands. These ligands modulate the receptor by inducing dynamic changes in the ligand binding domain that shift the C-terminal helix (H12) between active and inactive conformations. Despite decades of study, many questions persist regarding the nature of the inactive state and how ligands shift receptors between different states. Here, we use molecular dynamics (MD) simulations to investigate the timescale and energetic landscape of the conformational transition between inactive and active forms of progesterone receptor (PR) bound to a partial agonist. We observe that the microsecond timescale is insufficient to observe any transitions; only at millisecond timescales achieved via accelerated MD simulations do we find the inactive PR switches to the active state. Energetic analysis reveals that both active and inactive PR states represent energy minima separated by a barrier that can be traversed. In contrast, little or no transition is observed between active and inactive states when an agonist or antagonist is bound, confirming that ligand identity plays a key role in defining the energy landscape of nuclear receptor conformations.

Correlation Between the Clinical Diagnosis and Sonographic Diagnosis in Women with First-Trimester Vaginal Bleeding.

BACKGROUND: Vaginal bleeding is the most common cause of presentation at the emergency department in the first trimester. Clinical presentation helps determine the likely cause of first-trimester vaginal bleeding. However, ultrasound imaging is required to reach a definitive diagnosis. OBJECTIVE: To determine the relationship between clinical diagnosis and ultrasonographic findings in women with first-trimester vaginal bleeding. METHODS: A prospective longitudinal study was conducted on 94 pregnant patients with a history of bleeding per vagina (PV) in the first trimester by using transvaginal ultrasound. RESULTS: PV spotting was noted in 64.9% and heavy bleeding in 35.1%. The most common clinically associated symptom was abdominal pain (68, 72.3%), and the least common clinically associated symptom was vesicle expulsion (2.1%). The most common predisposing factor was fever (31, 33.0%). The most frequent clinical diagnosis was threatened abortion (48, 51.1%), and the least common clinical diagnosis was gestational trophoblastic disease (GTD) and inevitable abortion (1, 1.1%). The most common ultrasound diagnosis at the initial scan was incomplete abortion (19.2%), while at follow-up scans, it was threatened abortion (48, 51.1%). The overall concordance between clinical diagnosis and ultrasound was 38.8%, with both complete abortion and GTD showing a concordance of 100%. The least concordance was seen in missed abortions (25%). CONCLUSION: Clinical assessment is insufficient in the identification of the cause of vaginal bleeding due to the overall low concordance rate. A combination of clinical assessment and ultrasonography is required for decision-making in every case.

Nuclear receptor interdomain communication is mediated by the hinge with ligand specificity.

Nuclear receptors are ligand-induced transcription factors that bind directly to target genes and regulate their expression. Ligand binding initiates conformational changes that propagate to other domains, allosterically regulating their activity. The nature of this interdomain communication in nuclear receptors is poorly understood, largely owing to the difficulty of experimentally characterizing full-length structures. We have applied computational modeling approaches to describe and study the structure of the full length farnesoid X receptor (FXR), approximated by the DNA binding domain (DBD) and ligand binding domain (LBD) connected by the flexible hinge region. Using extended molecular dynamics simulations (> 10 microseconds) and enhanced sampling simulations, we provide evidence that ligands selectively induce domain rearrangement, leading to interdomain contact. We use protein-protein interaction assays to provide experimental evidence of these interactions, identifying a critical role of the hinge in mediating interdomain contact. Our results illuminate previously unknown aspects of interdomain communication in FXR and provide a framework to enable characterization of other full length nuclear receptors.

Accelerating the discovery of alkyl halide-derived natural products using halide depletion.

Even in the genomic era, microbial natural product discovery workflows can be laborious and limited in their ability to target molecules with specific structural features. Here we leverage an understanding of biosynthesis to develop a workflow that targets the discovery of alkyl halide-derived natural products by depleting halide anions, a key biosynthetic substrate for enzymatic halogenation, from microbial growth media. By comparing the metabolomes of bacterial cultures grown in halide-replete and deficient media, we rapidly discovered the nostochlorosides, the products of an orphan halogenase-encoding gene cluster from Nostoc punctiforme ATCC 29133. We further found that these products, a family of unusual chlorinated glycolipids featuring the rare sugar gulose, are polymerized via an unprecedented enzymatic etherification reaction. Together, our results highlight the power of leveraging an understanding of biosynthetic logic to streamline natural product discovery.

Lipoprotein-Associated Phospholipase A2 has Comparable Ability as Anthropometric Indices to Discriminate Cardiovascular Disease Risk: A Cross-Sectional Study.

BACKGROUND AND AIM: Available evidence suggests that the indices of obesity may serve as good predictors of cardiovascular disease (CVD). This study compared the ability of lipoprotein-associated phospholipase A2 (Lp-PLA2) and anthropometric indices to discriminate CVD risk among the apparently healthy staff of Babcock University in Southwest Nigeria. METHODS: A descriptive cross-sectional study was conducted among apparently healthy staff. Participants' weight, height, body mass index (BMI), waist circumference (WC), hip circumference (HC), neck circumference (NC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), wrist circumference (WrC), and blood pressure were measured. Venous blood was collected for Lp-PLA2, lipid profile, and fasting plasma glucose (FPG) estimation. CVD risk was defined as the presence of either general obesity or abdominal obesity, diabetes mellitus, dyslipidaemia, hypertension or smoking. The receiver operating characteristic curve was used to compare the ability of LpPLA2 and the anthropometric indices to discriminate CVD risk in male and female participants. RESULTS: Results showed that 75.7% (106) of the participants had CVD risk. Anthropometric indices (weight, BMI, WC, HC, NC, WrC, WHR, and WHtR), FPG, lipid profile and Lp-LPA2 were higher among participants with CVD risk (p<0.05). Among the men, LpPLA2 had the largest area under the curve (AUC) (AUC= 0.886, p<0.001), closely followed by BMI (AUC = 0.879, p<0.001), WC (AUC = 0.864, p<0.001), and WHtR (AUC= 0.866, p<0.001). Among the women, WHtR had the largest AUC of 0.995 (p<0.001), followed by WC (AUC = 0.990, p<0.001), BMI (AUC = 0.970, p<0.001), and Lp-PLA2 (AUC= 0.938, p<0.001). CONCLUSION: The abilities of Lp-PLA2 and anthropometric indices to predict CVD risk are comparable among the male and female apparently healthy staff of a private tertiary university in Southwest Nigeria. CONTEXTE ET OBJECTIF: Les données disponibles suggèrent que les indices d'obésité peuvent servir de bons prédicteurs des maladies cardiovasculaires (MCV). Cette étude a comparé la capacité de la phospholipase A2 associée aux lipoprotéines (Lp-PLA2) et des indices anthropométriques à discriminer le risque de MCV parmi le personnel apparemment en bonne santé de l'Université Babcock, dans le sud-ouest du Nigeria. MÉTHODES: Une étude descriptive transversale a été menée auprès de membres du personnel apparemment en bonne santé. Le poids, la taille, l'indice de masse corporelle (IMC), le tour de taille (WC), le tour de hanches (HC), le tour de cou (NC), le rapport taille-hanche (WHR), le rapport taille-hauteur (WHtR), le tour de poignet (WrC) et la pression artérielle des participants ont été mesurés. Du sang veineux a été prélevé pour mesurer la Lp-PLA2, le profil lipidique et la glycémie à jeun. Le risque de MCV a été défini comme la présence d'une obésité générale ou d'une obésité abdominale, d'un diabète sucré, d'une dyslipidémie, d'une hypertension ou d'un tabagisme. La courbe caractéristique du récepteur a été utilisée pour comparer la capacité de la Lp-PLA2 et des indices anthropométriques à discriminer le risque de MCV chez les hommes et les femmes. RÉSULTATS: Les résultats ont montré que 75,7 % (106) des participants présentaient un risque de MCV. Les indices anthropométriques (poids, IMC, tour de taille, HC, NC, WrC, WHR et WHtR), la glycémie, le profil lipidique et la Lp-LPA2 étaient plus élevés chez les participants présentant un risque de MCV (p<0,05). Chez les hommes, la Lp-PLA2 présentait la plus grande aire sous la courbe (AUC) (AUC = 0,886, p<0,001), suivie de près par l'IMC (AUC = 0,879, p <0,001), le tour de taille (AUC = 0,864, p <0,001) et le WHtR (AUC = 0,866, p <0,001).Chez les femmes, le WHtR présentait la plus grande aire sous la courbe de 0,995 (p<0,001), suivi du tour de taille (aire sous la courbe de 0,990, p<0,001), de l'IMC (aire sous la courbe de 0,970, p<0,001) et de la LpPLA2 (aire sous la courbe de 0,938, p<0,001). CONCLUSION: Les capacités de Lp-PLA2 et des indices anthropométriques à prédire le risque de MCV sont comparables parmi le personnel masculin et féminin apparemment en bonne santé d'une université tertiaire privée du sud-ouest du Nigeria. Mots-clés: Phospholipase A2 associée aux lipoprotéines, indices anthropométriques, risque cardiovasculaire, Nigeria.

The nuclear receptor LRH-1 discriminates between ligands using distinct allosteric signaling circuits.

Nuclear receptors (NRs) are transcription factors that regulate essential biological processes in response to cognate ligands. An important part of NR function involves ligand-induced conformational changes that recruit coregulator proteins to the activation function surface (AFS), ~15 Å away from the ligand-binding pocket. Ligands must communicate with the AFS to recruit appropriate coregulators and elicit different transcriptional outcomes, but this communication is poorly understood. These studies illuminate allosteric communication networks underlying activation of liver receptor homolog-1 (LRH-1), a NR that regulates development, metabolism, cancer progression, and intestinal inflammation. Using >100 µs of all-atom molecular dynamics simulations involving 74 LRH-1 complexes, we identify distinct signaling circuits used by active and inactive ligands for AFS communication. Inactive ligands communicate via strong, coordinated motions along paths through the receptor to the AFS. Activating ligands disrupt the "inactive" circuit and induce connectivity with a second allosteric site. Ligand-contacting residues in helix 7 help mediate the switch between circuits, suggesting new avenues for developing LRH-1-targeted therapeutics. We also elucidate aspects of coregulator signaling, showing that localized, destabilizing fluctuations are induced by inappropriate ligand-coregulator pairings. These studies have uncovered novel features of LRH-1 allostery, and the quantitative approach used to analyze many simulations provides a framework to study allosteric signaling in other receptors.

Intimate Partner Violence and Risk Factors among Women during the COVID-19 Movement Restriction in Nigeria: An Online Survey.

BACKGROUND: The rapid spread of the SARS-CoV-2 infection in the absence of treatment or the presence of vaccines is forcing nations to respond with strong preventive measures ranging from mitigation, containment, and in extreme cases, quarantines. While these measures are a useful measure of infection control, they can lead to significant social, economic, and psychological consequences. This study sought to establish the prevalence and risk factors of intimate partner violence during the COVID-19 movement restriction in Nigeria among girls and women. METHODS: An online-based questionnaire survey using Google Forms was conducted over four weeks among girls and women aged 15 years and above. Data analysis was performed using SPSS version 20, and logistic regression was used to determine risk factors for IPV experience during the lockdown. RESULTS: Overall, 32.8% of respondents reported ever experiencing IPV, and 42.5% experienced IPV during the lockdown. Verbal (35.1%) and psychological (24.1%) violence were the commonest forms of violence in the study. There was considerable overlap between the various forms of IPV in the study. Age less than 35 years (aOR = 1.3; CI = 1.2 - 1.4), resident in the northeast region (aOR=1.6; CI=1.41.9), alcohol (aOR=1.3;CI=1.2-1.5) and substance (aOR = 1.5; CI = 1.3 - 1.8) use, average family monthly income < $100 (aOR = 1.4;CI=1.2 - 1.5), daily or weekly income (aOR = 2.7; CI = 2.5-3.1) had an increased association with IPV during the lockdown, residency in the southeast region had lower odds of experiencing IPV (aOR=.0.5; CI = 0.3-0.8). CONCLUSION: The reported lockdown prevalence of IPV was 42.8%, with verbal and psychological violence being the most prevalent form of IPV. Age less than 35 years, resident in northeast and southeast, use of alcohol or substances, average family monthly income < $100, and partner being a daily-weekly earner was associated with IPV experience. Policymakers in the future should consider the consequences, including IPV, before issuing such an order.

CONTEXTE: La propagation rapide de l'infection par le CoV-2 du SRAS en l'absence de traitement ou présence de vaccins oblige les nations à réagir par des mesures préventives fortes allant de l'atténuation à l'endiguement et, dans les cas extrêmes, à la mise en quarantaine. Bien que ces mesures soient utiles pour contrôler l'infection, elles peuvent avoir des conséquences sociales, économiques et psychologiques importantes. Cette étude visait à établir la prévalence et les facteurs de risque de la violence exercée par le partenaire intime au cours de la restriction de mouvement du COVID-19 au Nigeria, chez les filles et les femmes. MÉTHODES: Une enquête par questionnaire en ligne utilisant google form a été menée pendant quatre semaines auprès de filles et de femmes âgées de 15 ans et plus. L'analyse des données a été réalisée à l'aide de la version 20 de SPSS et une régression logistique a été utilisée pour déterminer les facteurs de risque de violence conjugale pendant la période de restriction. RÉSULTATS: Dans l'ensemble, 32,8 % des personnes interrogées ont déclaré avoir déjà subi des VPI, et 42,5 % ont subi des VPI pendant l'enfermement. La violence verbale (35,1 %) et la violence psychologique (24,1 %) étaient les formes de violence les plus courantes dans l'étude. Il y avait un chevauchement considérable entre les différentes formes de VPI dans l'étude. L'âge inférieur à 35 ans (aOR=1,3 ; CI= 1,2 - 1,4), la résidence dans la région nord-est (aOR=1,6; CI=1,4-1,9), la consommation d'alcool (aOR=1,3; CI=1,2 - 1,5) et de substances (aOR=1,5 ; CI = 1,3 - 1,8), le revenu mensuel moyen de la famille < 100 $ (aOR=1. 4 ; IC = 1,2 - 1,5), le revenu quotidien ou hebdomadaire (aOR = 2,7 ; IC = 2,5-3,1) était davantage associé à la VPI pendant le lockdown, la résidence dans la région du sud-est avait moins de chances d'être victime de VPI (aOR = 0,0,5 ; IC = 0,3-0,8). CONCLUSION: La prévalence de la VPI pendant le lockdown était de 42,8 %, la violence verbale et psychologique étant la forme de VPI la plus répandue. L'âge inférieur à 35 and, le fait de résider dans le nord-est et le sud-est, la consommation d'alcool ou de substances, le revenu mensuel moyen de la famille inférieur à 100 dollars et le fait que le partenaire gagne sa vie toutes les semaines étaient associés à l'expérience de la VPI. À l'avenir, les décideurs politiques devraient prendre en compte les conséquences, y compris la VPI, avant d'émettre un tel ordre. Mots-clés: Violence entre partenaires intimes, COVID-19, Lockdowns, Nigeria, Violence fondée sur le genre.

Two enhancer binding proteins activate σ54-dependent transcription of a quorum regulatory RNA in a bacterial symbiont.

To colonize a host, bacteria depend on an ensemble of signaling systems to convert information about the various environments encountered within the host into specific cellular activities. How these signaling systems coordinate transitions between cellular states in vivo remains poorly understood. To address this knowledge gap, we investigated how the bacterial symbiont Vibrio fischeri initially colonizes the light organ of the Hawaiian bobtail squid Euprymna scolopes. Previous work has shown that the small RNA Qrr1, which is a regulatory component of the quorum-sensing system in V. fischeri, promotes host colonization. Here, we report that transcriptional activation of Qrr1 is inhibited by the sensor kinase BinK, which suppresses cellular aggregation by V. fischeri prior to light organ entry. We show that Qrr1 expression depends on the alternative sigma factor σ54 and the transcription factors LuxO and SypG, which function similar to an OR logic gate, thereby ensuring Qrr1 is expressed during colonization. Finally, we provide evidence that this regulatory mechanism is widespread throughout the Vibrionaceae family. Together, our work reveals how coordination between the signaling pathways underlying aggregation and quorum-sensing promotes host colonization, which provides insight into how integration among signaling systems facilitates complex processes in bacteria.

Psychometric Properties of the Modified Family Affluence Scale (FAS II) among Adolescents in Nigeria: A Preliminary Report.

OBJECTIVE: Social inequalities have serious health consequences for the developing child. Measuring these disparities is challenging, and the Family Affluence Scale (version II), a proxy indicator based on material wealth, was developed as a solution. However, it has not been validated for use in Sub-Saharan Africa and may not be applicable in developing countries. This preliminary study aimed to determine the convergent validity and reliability of a culturally adapted version of the FAS II. METHODS: A cross-sectional study was carried out among 422 senior secondary school students in Calabar, Nigeria. Modified versions of the Family Affluence Scale Version II (FAS II) were tested for their psychometric properties as proxy measures of socioeconomic status among Nigerian adolescents. Cronbach's alpha was computed as a measure of internal consistency, while Spearman's rank correlation and regression analysis were done to assess convergent validity. RESULTS: The mean sample age was 14.95 (±1.53) years, with an approximately equal gender distribution. Internal consistency was 0.68 for the 4-item version of the modified scale and increased to 0.75 when the item about travelling abroad was deleted. The modified FAS II scores (4 items) had a significant positive correlation with tuition cost (r=0.48, p<0.001), paternal educational attainment (r=0.27, p<0.001), and maternal educational attainment (r=0.30, p<0.001). Similarly, the 3-item version had a significant positive correlation with tuition cost (r=0.52, p<0.001), paternal educational attainment (r=0.24, p<0.001), and maternal educational attainment (r=0.30, p<0.001). Moderate (aOR: 4.25; 95%CI 2.45-7.39) and high affluence (aOR: 11.43; 95%CI 6.36-20.55) predicted attending more expensive schools. Moderate affluence (aOR: 2.15; 95%CI 1.28-3.62) and high affluence (aOR: 5.21; 95%CI 2.76-9.84) predicted a higher paternal education. Also, moderate affluence (aOR: 2.18; 95%CI 1.31-3.63) and high affluence (aOR: 7.42; 95%CI 3.76-14.66) predicted higher maternal education. The 3-item version performed similarly in terms of its predictive ability. CONCLUSION: The modified version of the FAS II appears to have sufficient validity and reliability for measuring the socio-economic status of adolescents in Nigeria.

OBJECTIF: Les inégalités sociales ont de graves conséquences sur lasanté de l'enfant en développement. Il est difficile de mesurer ces disparités, et l'échelle d'aisance familiale (version II), un indicateur indirect basé sur la richesse matérielle, a été mise au point pour y remédier. Cependant, elle n'a pas été validée pour une utilisation en Afrique subsaharienne et pourrait ne pas être applicable dans les pays en développement. L'objectif de cette étude préliminaire était de déterminer la validité convergente et la fiabilité d'une version culturellement adaptée du FAS II. MÉTHODES: Une étude transversale a été menée auprès de 422 élèves du deuxième cycle de l'enseignement secondaire à Calabar, au Nigeria. Des versions modifiées de la Family Affluence Scale Version II (FAS II) ont été testées pour leurs propriétés psychométriques en tant que mesures indirectes du statut socio-économique chez les adolescents nigérians. L'alpha de Cronbach a été calculé pour mesurer la cohérence interne, tandis que la corrélation de rang de Spearman et l'analyse de régression ont été effectuées pour évaluer la validité convergente. RÉSULTATS: L'âge moyen de l'échantillon était de 14,95 ans (±1,53), avec une répartition à peu près égale entre les sexes. La cohérence interne était de 0,68 pour la version à 4 items de l'échelle modifiée et a augmenté à 0,75 lorsque l'item sur les voyages à l'étranger a été supprimé. Les scores FAS II modifiés (4 items) présentaient une corrélation positive significative avec les frais de scolarité (r=0,48, p<0,001), le niveau d'études du père (r=0,27, p<0,001) et le niveau d'études de la mère (r=0,30, p<0,001). De même, la version à 3 questions présentait une corrélation positive significative avec les frais de scolarité (r=0,52, p<0,001), le niveau d'études du père (r=0,24, p<0,001) et le niveau d'études de la mère (r=0,30, p<0,001). Une aisance modérée (aOR : 4,25; 95%CI 2,45-7,39) et élevée (aOR : 11,43 ; 95%CI 6,36-20,55) prédit la fréquentation d'écoles plus chères. Une aisance modérée (aOR : 2,15; 95%CI 1,28-3,62) et une aisance élevée (aOR : 5,21 ; 95%CI 2,76-9,84) prédisaient un niveau d'éducation paternel plus élevé. De même, une aisance modérée (aOR : 2,18 ; 95%CI 1,31-3,63) et une aisance élevée (aOR : 7,42 ; 95%CI 3,76-14,66) permettaient de prédire un niveau d'éducation maternel plus élevé. La version à 3 items a donné des résultats similaires en termes de capacité prédictive. CONCLUSION: La version modifiée du FAS II semble avoir une validité et une fiabilité suffisantes pour mesurer le statut socio-économique des adolescents au Nigeria. Mots-clés: Adolescent, Famille, Déterminants sociaux de la santé, Nigeria, Pays en développement, Reproductibilité des résultats.

The nuclear receptor LRH-1 discriminates between ligands using distinct allosteric signaling circuits.

Nuclear receptors (NRs) are transcription factors that regulate essential biological processes in response to cognate ligands. An important part of NR function involves ligand-induced conformational changes that recruit coregulator proteins to the activation function surface (AFS), ~15 Å away from the ligand binding pocket. Ligands must communicate with the AFS to recruit appropriate coregulators and elicit different transcriptional outcomes, but this communication is poorly understood. These studies illuminate allosteric communication networks underlying activation of liver receptor homolog-1 (LRH-1), a NR that regulates development, metabolism, cancer progression and intestinal inflammation. Using >100 microseconds of all-atom molecular dynamics simulations involving 69 LRH-1 complexes, we identify distinct signaling circuits used by active and inactive ligands for AFS communication. Inactive ligands communicate via strong, coordinated motions along paths through the receptor to the AFS. Activating ligands disrupt the "inactive" circuit by inducing connectivity elsewhere. Ligand-contacting residues in helix 7 help mediate the switch between circuits, suggesting new avenues for developing LRH-1-targeted therapeutics. We also elucidate aspects of coregulator signaling, showing that localized, destabilizing fluctuations are induced by inappropriate ligand-coregulator pairings. These studies have uncovered novel features of LRH-1 allostery, and the quantitative approach used to analyze many simulations provides a framework to study allosteric signaling in other receptors.

Identification of an Evolutionarily Conserved Allosteric Network in Steroid Receptors.

Allosteric pathways in proteins describe networks comprising amino acid residues which may facilitate the propagation of signals between distant sites. Through inter-residue interactions, dynamic and conformational changes can be transmitted from the site of perturbation to an allosteric site. While sophisticated computational methods have been developed to characterize such allosteric pathways linking specific sites on proteins, few attempts have been made to apply these approaches toward identifying new allosteric sites. Here, we use molecular dynamics simulations and suboptimal path analysis to discover new allosteric networks in steroid receptors with a focus on evolutionarily conserved pathways. Using modern receptors and a reconstructed ancestral receptor, we identify networks connecting several sites to the activation function surface 2 (AF-2), the site of coregulator recruitment. One of these networks is conserved across the entire family, connecting a predicted allosteric site located between helices 9 and 10 of the ligand-binding domain. We investigate the basis of this conserved network as well as the importance of this site, discovering that the site lies in a region of the ligand-binding domain characterized by conserved inter-residue contacts. This study suggests an evolutionarily importance of the helix 9-helix 10 site in steroid receptors and identifies an approach that may be applied to discover previously unknown allosteric sites in proteins.

Bile acids and the gut microbiota: metabolic interactions and impacts on disease.

Despite decades of bile acid research, diverse biological roles for bile acids have been discovered recently due to developments in understanding the human microbiota. As additional bacterial enzymes are characterized, and the tools used for identifying new bile acids become increasingly more sensitive, the repertoire of bile acids metabolized and/or synthesized by bacteria continues to grow. Additionally, bile acids impact microbiome community structure and function. In this Review, we highlight how the bile acid pool is manipulated by the gut microbiota, how it is dependent on the metabolic capacity of the bacterial community and how external factors, such as antibiotics and diet, shape bile acid composition. It is increasingly important to understand how bile acid signalling networks are affected in distinct organs where the bile acid composition differs, and how these networks impact infectious, metabolic and neoplastic diseases. These advances have enabled the development of therapeutics that target imbalances in microbiota-associated bile acid profiles.

Interactions governing transcriptional activity of nuclear receptors.

The key players in transcriptional regulation are transcription factors (TFs), proteins that bind specific DNA sequences. Several mechanisms exist to turn TFs 'on' and 'off', including ligand binding which induces conformational changes within TFs, subsequently influencing multiple inter- and intramolecular interactions to drive transcriptional responses. Nuclear receptors are a specific family of ligand-regulated TFs whose activity relies on interactions with DNA, coregulator proteins and other receptors. These multidomain proteins also undergo interdomain interactions on multiple levels, further modulating transcriptional outputs. Cooperation between these distinct interactions is critical for appropriate transcription and remains an intense area of investigation. In this review, we report and summarize recent findings that continue to advance our mechanistic understanding of how interactions between nuclear receptors and diverse partners influence transcription.

The Impact of Co-Morbidities on the Pattern of Blood Pressure Control in Elderly Hypertensives in Nigeria.

INTRODUCTION: The elderly hypertensive patients often have increased prevalence of cardiometabolic risk factors and their attendant co-morbidities. The aim of this study was to determine the prevalence of cardiometabolic risk factors and blood pressure control among elderly hypertensive patients, and to determine the influence of modifiable cardiometabolic risk factors on the control of hypertension among elderly hypertensive patients. SUBJECTS AND METHODS: A case-control comparative and hospitalbased study involving a total of 190 consenting elderly (>65 years), hypertensive patients (subjects) (n=100) and normotensive controls (n=90) was carried out over a period of ten months. Using interviewer-administered questionnaire, biodata and information regarding their lifestyle was obtained. Standard protocols were used to measure blood pressure, weight, height, waist circumference, fasting plasma glucose and fasting lipid profile of the subjects. Body mass index was derived from weight and height. RESULTS: The mean age of the subjects was 71.5 ± 6.3 years and the controls was 72.3 ± 7.2 years. Forty-eight percent (48%) and 47.8% of the subjects and controls were females (p = 0.651). The level of control of hypertension was poor in over two-thirds (68%) of the elderly hypertensive patients. The prevalence of modifiable cardiometabolic risk factors burden was higher in the hypertensive subjects when compared with the controls. Prevalence of Dyslipidaemia was 76% in the subjects and 51% in the controls (p = 0.004). Prevalence of Diabetes Mellitus was 40% among the subjects and 17.8% in the controls (p = 0.0001); prevalence of Obesity was 24% in the subjects and 4.4% in the controls (p=<0.001); prevalence of excess alcohol intake was 49% in the subjects and 14.4% in the controls (p=<0.001). Prevalence of sedentary life style was high in both the subjects (53%) and controls (50%), p=0.679. Poor blood pressure control was predicted by dyslipidaemia and central obesity. CONCLUSION: The level of control of hypertension was poor among the elderly and modifiable cardiometabolic risk factors were relatively prevalent. Central obesity and dyslipidaemia were predictive of poor control of hypertension. Addressing these factors may therefore improve blood pressure control.

INTRODUCTION: Les patients hypertendus âgés présentent souvent une prévalence accrue de facteurs de risque cardiométaboliques et de leurs comorbidités. Le but de cette étude était de déterminer la prévalence des facteurs de risque cardiométabolique et le contrôle de la pression artérielle chez les patients hypertendus âgés, et de déterminer l'influence des facteurs de risque cardiométabolique modifiables sur le contrôle de l'hypertension chez les patients hypertendus âgés. SUJETS ET MÉTHODES: Une étude cas-témoins comparative et hospitalière portant sur un total de 190 patients âgés (e"65 ans) consentants, hypertendus (sujets) (n=100) et témoins normotendus (n=90) a été réalisée sur une période de dix mois. A l'aide d'un questionnaire administré par un enquêteur, des données biographiques et des informations concernant leur mode de vie ont été obtenues. Des protocoles standard ont été utilisés pour mesurer la pression artérielle, le poids, la taille, le tour de taille, la glycémie à jeun et le profil lipidique à jeun des sujets. L'indice de masse corporelle a été calculé à partir du poids et de la taille. RÉSULTATS: L'âge moyen des sujets était de 71,5±6,3 ans et celui des témoins de 72,3±7,2 ans. Quarante-huit pour cent (48 %) et 47,8 % des sujets et des témoins étaient des femmes (p=0,651). Le niveau de contrôle de l'hypertension était faible chez plus de deux tiers (68 %) des patients hypertendus âgés. La prévalence des facteurs de risque cardiométabolique modifiables était plus élevée chez les sujets hypertendus que chez les témoins. La prévalence de la dyslipidémie était de 76 % chez les sujets, 51 % chez les témoins (p=0,004). La prévalence du diabète sucré était de 40% chez les sujets et de 17,8% chez les témoins (p= 0,0001), la prévalence de l'obésité était de 24% chez les sujets et de 4,4% chez les témoins (p=<0,001), la prévalence de la consommation excessive d'alcool était de 49% chez les sujets et de 14,4% chez les témoins (p=<0,001). La prévalence du style de vie sédentaire était élevée chez les sujets (53%) et les témoins (50%), p=0,679. Un mauvais contrôle de la pression artérielle était prédit par la dyslipidémie et l'obésité centrale. CONCLUSION: Le niveau de contrôle de l'hypertension était faible chez les personnes âgées et les facteurs de risque cardiométaboliques modifiables étaient relativement prévalents. L'obésité centrale et la dyslipidémie étaient prédictives d'un mauvais contrôle de l'hypertension. La prise en compte de ces facteurs peut donc améliorer le contrôle de la pression artérielle. Mots clés: Pression artérielle, Facteurs de risque cardiométabolique, Personnes âgées.

Ligand-induced shifts in conformational ensembles that describe transcriptional activation.

Nuclear receptors function as ligand-regulated transcription factors whose ability to regulate diverse physiological processes is closely linked with conformational changes induced upon ligand binding. Understanding how conformational populations of nuclear receptors are shifted by various ligands could illuminate strategies for the design of synthetic modulators to regulate specific transcriptional programs. Here, we investigate ligand-induced conformational changes using a reconstructed, ancestral nuclear receptor. By making substitutions at a key position, we engineer receptor variants with altered ligand specificities. We combine cellular and biophysical experiments to characterize transcriptional activity, as well as elucidate mechanisms underlying altered transcription in receptor variants. We then use atomistic molecular dynamics (MD) simulations with enhanced sampling to generate ensembles of wildtype and engineered receptors in combination with multiple ligands, followed by conformational analysis and correlation of MD-based predictions with functional ligand profiles. We determine that conformational ensembles accurately describe ligand responses based on observed population shifts. These studies provide a platform which will allow structural characterization of physiologically-relevant conformational ensembles, as well as provide the ability to design and predict transcriptional responses in novel ligands.

Inhibitors of ApiAP2 protein DNA binding exhibit multistage activity against Plasmodium parasites.

Plasmodium parasites are reliant on the Apicomplexan AP2 (ApiAP2) transcription factor family to regulate gene expression programs. AP2 DNA binding domains have no homologs in the human or mosquito host genomes, making them potential antimalarial drug targets. Using an in-silico screen to dock thousands of small molecules into the crystal structure of the AP2-EXP (Pf3D7_1466400) AP2 domain (PDB:3IGM), we identified putative AP2-EXP interacting compounds. Four compounds were found to block DNA binding by AP2-EXP and at least one additional ApiAP2 protein. Our top ApiAP2 competitor compound perturbs the transcriptome of P. falciparum trophozoites and results in a decrease in abundance of log2 fold change > 2 for 50% (46/93) of AP2-EXP target genes. Additionally, two ApiAP2 competitor compounds have multi-stage anti-Plasmodium activity against blood and mosquito stage parasites. In summary, we describe a novel set of antimalarial compounds that interact with AP2 DNA binding domains. These compounds may be used for future chemical genetic interrogation of ApiAP2 proteins or serve as starting points for a new class of antimalarial therapeutics.

Association between Physical Inactivity and Metabolic Syndrome in South-West Nigeria.

BACKGROUND: We assessed the prevalence of physical inactivity and its association with metabolic syndrome in a rural community and an urban community in South-west Nigeria. METHODS: A cross-sectional descriptive study among healthy volunteers 18 years and above was conducted in urban (Ikeja) and rural (Ilara-Akaka) communities in Lagos and Ogun State, respectively, using a multi-stage sampling technique. Selfreported physical activity [measured in metabolic equivalent (MET)] was assessed using the World Health Organization Global Physical Activity Questionnaire. Metabolic syndrome was assessed using the definition recommended by the Joint Interim Statement of the International Diabetes Federation Task Force. Regression analysis of factors associated with physical inactivity was done using IBM Statistics version 26. RESULTS: A total of 437 participants were recruited with a median age of 45 years (IQR 38,56). The prevalence of physical inactivity was 24.9%. There was a significant negative correlation between metabolic syndrome components and total MET except for high-density lipoprotein (HDL) cholesterol. Being a female (AOR 1.9 95% CI 1.0 - 3.5, p=0.040), living in an urban community (AOR 1.81 95% CI 1.1 - 2.9, p=0.014), and having metabolic syndrome (AOR 3.98 95% CI 2.2 - 6.7, p <0.001) were associated with physical inactivity. Having raised fasting plasma glucose, elevated blood pressure, increased waist circumference, and reduced HDL cholesterol were associated with physical inactivity. CONCLUSION: There was an association between metabolic syndrome and its components with physical inactivity. In order to mitigate the effects of metabolic syndrome, public health actions that will promote physical activity, especially in urban communities, are urgently needed.

CONTEXTE: Nous avons évalué la prévalence de l'inactivité physique et son association avec le syndrome métabolique dans une communauté rurale et une communauté urbaine du sud-ouest du Nigeria. MÉTHODES: Une étude descriptive transversale a été menée auprès de volontaires sains âgés de 18 ans et plus dans des communautés urbaines (Ikeja) et rurales (Ilara-Akaka) des États de Lagos et d'Ogun, respectivement, à l'aide d'une technique d'échantillonnage à plusieurs degrés. L'activité physique autodéclarée [mesurée en équivalent métabolique (MET)] a été évaluée à l'aide du questionnaire global sur l'activité physique de l'Organisation mondiale de la santé. Le syndrome métabolique a été évalué à l'aide de la définition recommandée par le Joint Interim Statement of the International Diabetes Federation Task Force. L'analyse de régression des facteurs associés à l'inactivité physique a été effectuée à l'aide de IBM Statistics version 26. RÉSULTATS: Un total de 437 participants ont été recrutés avec un âge médian de 45 ans (IQR 38,56). La prévalence de l'inactivité physique était de 24,9 %. Il y avait une corrélation négative significative entre les composants du syndrome métabolique et le MET total, à l'exception du cholestérol à lipoprotéines de haute densité (HDL). Le fait d'être une femme (AOR 1,9 IC 95 % 1,0 - 3,5, p=0,040), de vivre dans une communauté urbaine (AOR 1,81 IC 95 % 1,1 - 2,9, p=0,014) et d'avoir un syndrome métabolique (AOR 3,98 IC 95 % 2,2 - 6,7, p<0,001) était associé à l'inactivité physique. Une glycémie à jeun élevée, une pression artérielle élevée, un tour de taille accru et un taux de cholestérol HDL réduit étaient associés à l'inactivité physique. CONCLUSION: Il existe une association entre le syndrome métabolique et ses composantes et la sédentarité. Afin d'atténuer les effets du syndrome métabolique, il est urgent de mettre en place des actions de santé publique visant à promouvoir l'activité physique, en particulier dans les communautés urbaines. Mots clés: Inactivité physique, syndrome métabolique, Nigeria.