Transcriptional responses of Neisseria gonorrhoeae to glucose and lactate: implications for resistance to oxidative damage and biofilm formation.

Understanding how bacteria adapt to different environmental conditions is crucial for advancing knowledge regarding pathogenic mechanisms that operate during infection as well as efforts to develop new therapeutic strategies to cure or prevent infections. Here, we investigated the transcriptional response of Neisseria gonorrhoeae, the causative agent of gonorrhea, to L-lactate and glucose, two important carbon sources found in the host environment. Our study revealed extensive transcriptional changes that gonococci make in response to L-lactate, with 37% of the gonococcal transcriptome being regulated, compared to only 9% by glucose. We found that L-lactate induces a transcriptional program that would negatively impact iron transport, potentially limiting the availability of labile iron, which would be important in the face of the multiple hydrogen peroxide attacks encountered by gonococci during its lifecycle. Furthermore, we found that L-lactate-mediated transcriptional response promoted aerobic respiration and dispersal of biofilms, contrasting with an anaerobic condition previously reported to favor biofilm formation. Our findings suggest an intricate interplay between carbon metabolism, iron homeostasis, biofilm formation, and stress response in N. gonorrhoeae, providing insights into its pathogenesis and identifying potential therapeutic targets.IMPORTANCEGonorrhea is a prevalent sexually transmitted infection caused by the human pathogen Neisseria gonorrhoeae, with ca. 82 million cases reported worldwide annually. The rise of antibiotic resistance in N. gonorrhoeae poses a significant public health threat, highlighting the urgent need for alternative treatment strategies. By elucidating how N. gonorrhoeae responds to host-derived carbon sources such as L-lactate and glucose, this study offers insights into the metabolic adaptations crucial for bacterial survival and virulence during infection. Understanding these adaptations provides a foundation for developing novel therapeutic approaches targeting bacterial metabolism, iron homeostasis, and virulence gene expression. Moreover, the findings reported herein regarding biofilm formation and L-lactate transport and metabolism contribute to our understanding of N. gonorrhoeae pathogenesis, offering potential avenues for preventing and treating gonorrhea infections.

Time-dependent changes in feeding behavior and energy balance associated with weight gain in mice fed obesogenic diets.

OBJECTIVE: Obesity is characterized by dysregulated homeostatic mechanisms resulting in positive energy balance; however, when this dysregulation occurs is unknown. We assessed the time course of alterations to behaviors promoting weight gain in male and female mice switched to an obesogenic high-fat diet (HFD). METHODS: Male and female C57BL/6J mice were housed in metabolic chambers and were switched from chow to a 60% or 45% HFD for 4 and 3 weeks, respectively. Food intake, meal patterns, energy expenditure (EE), and body weight were continuously measured. A separate cohort of male mice was switched from chow to a 60% HFD and was given access to locked or unlocked running wheels. RESULTS: Switching mice to obesogenic diets promotes transient bouts of hyperphagia during the first 2 weeks followed by persistent caloric hyperphagia. EE increases but not sufficiently enough to offset increased caloric intake, resulting in a sustained net positive energy balance. Hyperphagia is associated with consumption of calorically larger meals (impaired satiation) more frequently (impaired satiety), particularly during the light cycle. Running wheel exercise delays weight gain in male mice fed a 60% HFD by enhancing satiation and increasing EE. However, exercise effects on satiation are no longer apparent after 2 weeks, coinciding with weight gain. CONCLUSIONS: Exposure to obesogenic diets engages homeostatic regulatory mechanisms for ~2 weeks that ultimately fail, and consequent weight gain is characterized by impaired satiation and satiety. Insights into the etiology of obesity can be obtained by investigating changes to satiation and satiety mechanisms during the initial ~2 weeks of HFD exposure.

AgRP neurons mediate activity-dependent development of oxytocin connectivity and autonomic regulation.

During postnatal life, the adipocyte-derived hormone leptin is required for proper targeting of neural inputs to the paraventricular nucleus of the hypothalamus (PVH) and impacts the activity of neurons containing agouti-related peptide (AgRP) in the arcuate nucleus of the hypothalamus. Activity-dependent developmental mechanisms are known to play a defining role during postnatal organization of neural circuits, but whether leptin-mediated postnatal neuronal activity specifies neural projections to the PVH or impacts downstream connectivity is largely unexplored. Here, we blocked neuronal activity of AgRP neurons during a discrete postnatal period and evaluated development of AgRP inputs to defined regions in the PVH, as well as descending projections from PVH oxytocin neurons to the dorsal vagal complex (DVC) and assessed their dependence on leptin or postnatal AgRP neuronal activity. In leptin-deficient mice, AgRP inputs to PVH neurons were significantly reduced, as well as oxytocin-specific neuronal targeting by AgRP. Moreover, downstream oxytocin projections from the PVH to the DVC were also impaired, despite the lack of leptin receptors found on PVH oxytocin neurons. Blocking AgRP neuron activity specifically during early postnatal life reduced the density of AgRP inputs to the PVH, as well as the density of projections from PVH oxytocin neurons to the DVC, and these innervation deficits were associated with dysregulated autonomic function. These findings suggest that postnatal targeting of descending PVH oxytocin projections to the DVC requires leptin-mediated AgRP neuronal activity, and represents a novel activity-dependent mechanism for hypothalamic specification of metabolic circuitry, with consequences for autonomic regulation. Significance statement: Hypothalamic neural circuits maintain homeostasis by coordinating endocrine signals with autonomic responses and behavioral outputs to ensure that physiological responses remain in tune with environmental demands. The paraventricular nucleus of the hypothalamus (PVH) plays a central role in metabolic regulation, and the architecture of its neural inputs and axonal projections is a defining feature of how it receives and conveys neuroendocrine information. In adults, leptin regulates multiple aspects of metabolic physiology, but it also functions during development to direct formation of circuits controlling homeostatic functions. Here we demonstrate that leptin acts to specify the input-output architecture of PVH circuits through an activity-dependent, transsynaptic mechanism, which represents a novel means of sculpting neuroendocrine circuitry, with lasting effects on how the brain controls energy balance.

Caracterización del infarto agudo de miocardio con elevación del segmento st en pacientes atendidos en un centro de referencia. Periodo 2021-2023

Introducción: el riesgo de aparición del infarto agudo de miocardio está relacionada con varias comorbilidades, muchas de las cuales son prevenibles y tratables. El infarto agudo de miocardio tiene un impacto relevante en términos de mortalidad y número de hospitalizaciones. Objetivos: determinar las características clínica-epidemiológicas del infarto agudo de miocardio con elevación del segmento ST en pacientes atendidos en el Centro Médico Nacional-Hospital Nacional, durante el periodo 2021-2023. Metodología: el diseño del estudio fue observacional, descriptivo de corte transversal, sobre las características clínica-epidemiológicas del infarto agudo de miocardio con elevación del segmento ST en pacientes mayores de edad atendidos en el Centro Médico Nacional-Hospital Nacional, durante el periodo 2021-2023. Resultados: se analizaron 102 expedientes de pacientes con diagnóstico de infarto agudo de miocardio con elevación del segmento ST con una media de 64 ± 12 años; el 68 % (n = 69) correspondió al sexo masculino, con una edad promedio de 62 años, y en relación a las mujeres el promedio fue de 64 años. El motivo de consulta principal fue el dolor precordial y la cara miocárdica más afectada de acuerdo con el electrocardiograma inicial fue la cara anteroseptal. La mortalidad intrahospitalaria fue del 16 %, el 68 % correspondió a varones. La comorbilidad más frecuente fue la hipertensión arterial. Conclusión: La hipertensión arterial es la patología más prevalente. Asimismo, son habituales la obesidad, el tabaquismo y la diabetes mellitus. Las comorbilidades están en relación directa con la edad y prevalecen en mayores de 60 años. El infarto agudo de miocardio con elevación del segmento ST es más frecuente en el sexo masculino.

Introduction: the risk of acute myocardial infarction is related to several comorbidities, many of which are preventable and treatable. Acute myocardial infarction has a relevant impact in terms of mortality and number of hospitalizations. Objectives: the design of the study was observational, descriptive, cross-sectional, on the clinical characteristics of ST-segment elevation myocardial infarction, in adult patients treated at the Centro Médico Nacional-Hospital Nacional, during the period 2021-2023. Methodology: the design of the study was observational, descriptive, cross-sectional, on the clinical-epidemiological characteristics of acute myocardial infarction with ST segment elevation in adult patients treated at the National Medical Center-National Hospital, during the period 2021-2023. Results: 102 records of patients with a diagnosis of ST-segment elevation myocardial infarction with a mean age of 64 ± 12 years were analyzed; 68 % (n = 69) were male, with an average age of 62 years, and in relation to women the average was 64 years. The main reason for consultation was precordial pain and the most affected myocardial aspect according to the initial electrocardiogram was the anteroseptal aspect. In-hospital mortality was 16 %, 68 % of which were men. The most frequent comorbidity was arterial hypertension. Conclusion: high blood pressure is the most prevalent pathology. Likewise, obesity, smoking and diabetes mellitus are common. Comorbidities are directly related to age and prevail in those over 60 years of age. ST-segment elevation myocardial infarction is more common in males.

Hormonal steroids induce multidrug resistance and stress response genes in Neisseria gonorrhoeae by binding to MtrR.

Transcriptional regulator MtrR inhibits the expression of the multidrug efflux pump operon mtrCDE in the pathogenic bacterium Neisseria gonorrhoeae. Here, we show that MtrR binds the hormonal steroids progesterone, ß-estradiol, and testosterone, which are present at urogenital infection sites, as well as ethinyl estrogen, a component of some hormonal contraceptives. Steroid binding leads to the decreased affinity of MtrR for cognate DNA, increased mtrCDE expression, and enhanced antimicrobial resistance. Furthermore, we solve crystal structures of MtrR bound to each steroid, thus revealing their binding mechanisms and the conformational changes that induce MtrR.

Time dependent changes in feeding behavior and energy balance associated with weight gain in mice fed obesogenic diets.

Obesity is characterized by dysregulated homeostatic mechanisms resulting in positive energy balance, yet when this dysregulation occurs is unknown. We assessed the time course of alterations to behaviors promoting weight gain in male and female mice switched to obesogenic 60% or 45% high fat diet (HFD). Switching mice to obesogenic diets promotes transient bouts of hyperphagia during the first 2 weeks followed by persistent caloric hyperphagia. Energy expenditure increases but not sufficiently to offset increased caloric intake, resulting in a sustained net positive energy balance. Hyperphagia is associated with consumption of calorically larger meals (impaired satiation) more frequently (impaired satiety) particularly during the light-cycle. Running wheel exercise delays weight gain in 60% HFD-fed male mice by enhancing satiation and increasing energy expenditure. However, exercise effects on satiation are no longer apparent after 2 weeks, coinciding with weight gain. Thus, exposure to obesogenic diets engages homeostatic regulatory mechanisms for ∼2 weeks that ultimately fail, and consequent weight gain is characterized by impaired satiation and satiety. Insights into the etiology of obesity can be obtained by investigating changes to satiation and satiety mechanisms during the initial ∼2 weeks of HFD exposure. What is already known about this subject?: Obesity is associated with dysregulated homeostatic mechanisms.Increased caloric consumption contributes to obesity.Obese rodents tend to eat larger, more frequent meals. What are the new findings in your manuscript?: Exposure to obesogenic diets promotes transient attempts to maintain weight homeostasis.After ∼2 weeks, caloric hyperphagia exceeds increased energy expenditure, promoting weight gain.This is associated with consumption of larger, more frequent meals. How might your results change the direction of research or the focus of clinical practice?: Our findings suggest that molecular studies focusing on mechanisms that regulate meal size and frequency, particularly those engaged during the first ∼2 weeks of obesogenic diet feeding that eventually fail, can provide unique insight into the etiology of obesity.

Complicaciones vasculares en pacientes diabéticos con hemoglobina glicosilada alterada internados en el Centro Médico Nacional - Hospital Nacional periodo 2022 - 2023 / Vascular complications in diabetic patients with altered glycated hemoglobin admitted to Centro Médico Nacional - Hospital Nacional period 2022 ­ 2023

Introducción: la diabetes mellitus es una enfermedad crónica que, al no ser controlada, puede desencadenar en complicaciones macro y microvasculares. Uno de los indicadores de un adecuado control glucémico es la hemoglobina glicosilada. Objetivos: determinar la frecuencia de complicaciones macro y microvasculares en pacientes diabéticos tipo 2 con hemoglobina glicosilada alterada internados en el Hospital Nacional de Itauguá periodo 2022 - 2023 Metodología: estudio observacional, descriptivo de corte transversal que incluyó a 170 pacientes adultos internados en el servicio de clínica médica del Hospital Nacional (Itauguá, Paraguay) durante los años 2022 y 2023. Resultados: la edad media fue de 58 ± 12 años, con predominio del sexo femenino (51 %). La complicación más frecuentemente diagnosticada fue la enfermedad del pie relacionada a la diabetes con 83 pacientes (49 %), seguido por retinopatía diabética 23 (14 %). El valor promedio de hemoglobina glicosilada fue de 10 ± 2 %. Solamente 6 (4 %) del total de pacientes presentó un valor de HbA1C≥ 7,1 %. La comorbilidad asociada más frecuente fue la hipertensión arterial 87 (51 %). El 91 % de los pacientes conocía ser portador de la enfermedad, el 80 % recibía algún tipo de tratamiento. Conclusiones: el pie diabético fue la complicación vascular diagnosticada con mayor ,frecuencia, especialmente en pacientes con HbA1C≥ 7,1 %.

Introduction: diabetes mellitus is a chronic disease that, if not controlled, can lead to macro- and microvascular complications. One of the indicators of adequate glycemic control is glycosylated hemoglobin. Objectives: to determine the frequency of macro and microvascular complications in type 2 diabetic patients with altered glycosylated hemoglobin admitted to the Hospital Nacional from 2022 to 2023 Methodology: this was an observational, descriptive, cross-sectional study that included 170 adult patients admitted to the Internal Medicine service of the Hospital Nacional (Itauguá, Paraguay) during the years 2022 and 2023. Results: the mean age was 58 ± 12 years, with a predominance of the female sex (51 %). The most frequently diagnosed complication was foot disease related to diabetes with 83 patients (49 %), followed by diabetic retinopathy 23 (14 %). The average value of glycosylated hemoglobin was 10 ± 2 %. Only 6 (4 %) of the total patients had an HbA1C value ≤7 %. The most frequent associated comorbidity was arterial hypertension 87 (51 %). 91 % of the patients knew they were carriers of the disease, 80 % received some type of treatment. Conclusions: diabetic foot was the most frequently diagnosed vascular complication, especially in patients with HbA1C ≥7.1 %.

Infecciones más frecuentes en pacientes con Lupus Eritematoso Sistémico internados en el Servicio de Clínica Médica del Hospital Nacional / Most frequent infections in patients with Systemic Lupus Erythematosus admitted to the Medical Clinic Service of the Hospital Nacional

Introducción: el lupus eritematoso sistémico (LES) se conoce como una enfermedad autoinmune multisistémica, cuya causa es desconocida, se caracteriza por la presencia de complejos inmunes y autoanticuerpos. En series internacionales se describe una presentación de procesos infecciosos en estos pacientes hasta en un 75 % de los casos, las infecciones ocurren tanto al inicio de la enfermedad como en etapas tardías, y son causa directa de muerte en 30 % a 60 % de los casos y motivo de hospitalización hasta de 30 %. Objetivos: determinar los procesos infecciosos más frecuentes en pacientes con lupus eritematoso sistémico internados en el Servicio de Clínica Médica del Hospital Nacional en el periodo 2022-2023. Metodología: diseño observacional, descriptivo de corte transversal de pacientes con diagnóstico de lupus eritematoso sistémico según criterios de European League Against Rheumatism (EULAR)-2019 que se encuentran internados en el servicio de Clínica Médica del Hospital Nacional (Itaugua-Paraguay) en el periodo de 2022-2023. Resultados: la edad media de los pacientes fue de 34 años, con predominio del sexo femenino en el 88.18 %. Las infecciones del aparato respiratorio fue la más frecuentemente diagnosticada en 50 (45.45 %) pacientes, seguido por la infección de vías urinarias 47 (42.38 %) pacientes, el condicionante de riesgo predominante fue el uso de corticoides en un total 105 (96.40 %) pacientes, se estableció en un total de 97 (88.18 %) pacientes con antibioticoterapia, dentro del aspecto demográfico de la zona urbana 56 (50.90 %) pacientes y rural 54(49.1 %). Conclusión: la infección del aparato respiratorio fue la infección más frecuente, el condicionante de riesgo predominante es el uso de corticoides y recibieron antibioticoterapia la cual en monoterapia fue la más utilizada

Introduction: systemic lupus erythematosus (SLE) is known as a multisystem autoimmune disease, whose cause is unknown, and is characterized by the presence of immune complexes and autoantibodies. In international series, presentation of infectious processes is described in these patients in up to 75 % of cases. Infections occur both at the beginning of the disease and in late stages, and are a direct cause of death in 30 % to 60 % of patients. Cases and reason for hospitalization up to 30 %. Objectives: determine the most frequent infectious processes in patients with systemic lupus erythematosus admitted to the Medical Clinic Service of the Hospital Nacional in the period 2022-2023. Methodology: observational, descriptive cross-sectional design of patients with a diagnosis of systemic lupus erythematosus according to criteria of European League Against Rheumatism (EULAR)-2019 who are admitted to the Medical Clinic service of the Hospital Nacional (Itauguá-Paraguay) in the period of 2022-2023. Results: the average age of the patients was 34 years, with a predominance of the female sex in 88.18 %. Respiratory system infections were the most frequently diagnosed in 50 (45.45 %) patients, followed by urinary tract infection in 47 (42.38 %) patients. The predominant risk factor was the use of corticosteroids in a total of 105 (96.40 %) patients, it was established in a total of 97 (88.18 %) patients with antibiotic therapy, within the demographic aspect of the urban area 56 (50.90 %) patients and rural 54 (49.1 %). Conclusion: respiratory tract infection was the most frequent infection, the predominant risk factor is the use of corticosteroids and they received antibiotic therapy, which in monotherapy was the most used.

Glucagon-like peptide-1 receptor activation stimulates PKA-mediated phosphorylation of Raptor and this contributes to the weight loss effect of liraglutide.

The canonical target of the glucagon-like peptide-1 receptor (GLP-1R), Protein Kinase A (PKA), has been shown to stimulate mechanistic Target of Rapamycin Complex 1 (mTORC1) by phosphorylating the mTOR-regulating protein Raptor at Ser791 following ß-adrenergic stimulation. The objective of these studies is to test whether GLP-1R agonists similarly stimulate mTORC1 via PKA phosphorylation of Raptor at Ser791 and whether this contributes to the weight loss effect of the therapeutic GLP-1R agonist liraglutide. We measured phosphorylation of the mTORC1 signaling target ribosomal protein S6 in Chinese Hamster Ovary cells expressing GLP-1R (CHO-Glp1r) treated with liraglutide in combination with PKA inhibitors. We also assessed liraglutide-mediated phosphorylation of the PKA substrate RRXS*/T* motif in CHO-Glp1r cells expressing Myc-tagged wild-type (WT) Raptor or a PKA-resistant (Ser791Ala) Raptor mutant. Finally, we measured the body weight response to liraglutide in WT mice and mice with a targeted knock-in of PKA-resistant Ser791Ala Raptor. Liraglutide increased phosphorylation of S6 and the PKA motif in WT Raptor in a PKA-dependent manner but failed to stimulate phosphorylation of the PKA motif in Ser791Ala Raptor in CHO-Glp1r cells. Lean Ser791Ala Raptor knock-in mice were resistant to liraglutide-induced weight loss but not setmelanotide-induced (melanocortin-4 receptor-dependent) weight loss. Diet-induced obese Ser791Ala Raptor knock-in mice were not resistant to liraglutide-induced weight loss; however, there was weight-dependent variation such that there was a tendency for obese Ser791Ala Raptor knock-in mice of lower relative body weight to be resistant to liraglutide-induced weight loss compared to weight-matched controls. Together, these findings suggest that PKA-mediated phosphorylation of Raptor at Ser791 contributes to liraglutide-induced weight loss.

Gßγ-SNAP25 exocytotic brake removal enhances insulin action, promotes adipocyte browning, and protects against diet-induced obesity.

Negative regulation of exocytosis from secretory cells is accomplished through inhibitory signals from Gi/o GPCRs by Gßγ subunit inhibition of 2 mechanisms: decreased calcium entry and direct interaction of Gßγ with soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor (SNARE) plasma membrane fusion machinery. Previously, we disabled the second mechanism with a SNAP25 truncation (SNAP25Δ3) that decreased Gßγ affinity for the SNARE complex, leaving exocytotic fusion and modulation of calcium entry intact and removing GPCR-Gßγ inhibition of SNARE-mediated exocytosis. Here, we report substantial metabolic benefit in mice carrying this mutation. Snap25Δ3/Δ3 mice exhibited enhanced insulin sensitivity and beiging of white fat. Metabolic protection was amplified in Snap25Δ3/Δ3 mice challenged with a high-fat diet. Glucose homeostasis, whole-body insulin action, and insulin-mediated glucose uptake into white adipose tissue were improved along with resistance to diet-induced obesity. Metabolic protection in Snap25Δ3/Δ3 mice occurred without compromising the physiological response to fasting or cold. All metabolic phenotypes were reversed at thermoneutrality, suggesting that basal autonomic activity was required. Direct electrode stimulation of sympathetic neuron exocytosis from Snap25Δ3/Δ3 inguinal adipose depots resulted in enhanced and prolonged norepinephrine release. Thus, the Gßγ-SNARE interaction represents a cellular mechanism that deserves further exploration as an additional avenue for combating metabolic disease.

Hormonal steroids bind the Neisseria gonorrhoeae multidrug resistance regulator, MtrR, to induce a multidrug binding efflux pump and stress-response sigma factor.

Overexpression of the multidrug efflux pump MtrCDE, a critical factor of multidrug-resistance in Neisseria gonorrhoeae , the causative agent of gonorrheae, is repressed by the transcriptional regulator, MtrR (multiple transferable resistance repressor). Here, we report the results from a series of in vitro experiments to identify innate, human inducers of MtrR and to understand the biochemical and structural mechanisms of the gene regulatory function of MtrR. Isothermal titration calorimetry experiments reveal that MtrR binds the hormonal steroids progesterone, ß-estradiol, and testosterone, all of which are present at significant concentrations at urogenital infection sites as well as ethinyl estrogen, a component of some birth control pills. Binding of these steroids results in decreased affinity of MtrR for cognate DNA, as demonstrated by fluorescence polarization-based assays. The crystal structures of MtrR bound to each steroid provided insight into the flexibility of the binding pocket, elucidated specific residue-ligand interactions, and revealed the conformational consequences of the induction mechanism of MtrR. Three residues, D171, W136 and R176 are key to the specific binding of these gonadal steroids. These studies provide a molecular understanding of the transcriptional regulation by MtrR that promotes N. gonorrhoeae survival in its human host.

Fibroblast growth factor-21 is required for weight loss induced by the glucagon-like peptide-1 receptor agonist liraglutide in male mice fed high carbohydrate diets.

OBJECTIVE: Glucagon-like peptide-1 receptor (GLP-1R) agonists (GLP-1RA) and fibroblast growth factor-21 (FGF21) confer similar metabolic benefits. GLP-1RA induce FGF21, leading us to investigate mechanisms engaged by the GLP-1RA liraglutide to increase FGF21 levels and the metabolic relevance of liraglutide-induced FGF21. METHODS: Circulating FGF21 levels were measured in fasted male C57BL/6J, neuronal GLP-1R knockout, ß-cell GLP-1R knockout, and liver peroxisome proliferator-activated receptor alpha knockout mice treated acutely with liraglutide. To test the metabolic relevance of liver FGF21 in response to liraglutide, chow-fed control and liver Fgf21 knockout (LivFgf21-/-) mice were treated with vehicle or liraglutide in metabolic chambers. Body weight and composition, food intake, and energy expenditure were measured. Since FGF21 reduces carbohydrate intake, we measured body weight in mice fed matched diets with low- (LC) or high-carbohydrate (HC) content and in mice fed a high-fat, high-sugar (HFHS) diet. This was done in control and LivFgf21-/- mice and in mice lacking neuronal ß-klotho (Klb) expression to disrupt brain FGF21 signaling. RESULTS: Liraglutide increases FGF21 levels independently of decreased food intake via neuronal GLP-1R activation. Lack of liver Fgf21 expression confers resistance to liraglutide-induced weight loss due to attenuated reduction of food intake in chow-fed mice. Liraglutide-induced weight loss was impaired in LivFgf21-/- mice when fed HC and HFHS diets but not when fed a LC diet. Loss of neuronal Klb also attenuated liraglutide-induced weight loss in mice fed HC or HFHS diets. CONCLUSIONS: Our findings support a novel role for a GLP-1R-FGF21 axis in regulating body weight in a dietary carbohydrate-dependent manner.

The TAS1R2 sweet taste receptor regulates skeletal muscle mass and fitness.

Muscle fitness and mass deteriorate under the conditions of obesity and aging for reasons yet to be fully elucidated. Herein, we describe a novel pathway linking peripheral nutrient sensing and skeletal muscle function through the sweet taste receptor TAS1R2 and the involvement of ERK2-PARP1-NAD signaling axis. Muscle-specific deletion of TAS1R2 (mKO) in mice produced elevated NAD levels due to suppressed PARP1 activity, improved mitochondrial function, increased muscle mass and strength, and prolonged running endurance. Deletion of TAS1R2 in obese or aged mice also ameliorated the decline in muscle mass and fitness arising from these conditions. Remarkably, partial loss-of-function of TAS1R2 (rs35874116) in older, obese humans recapitulated the healthier muscle phenotype displayed by mKO mice in response to exercise training. Our findings show that inhibition of the TAS1R2 signaling in skeletal muscle is a promising therapeutic approach to preserve muscle mass and function.

Liver Fibroblast Growth Factor 21 (FGF21) is Required for the Full Anorectic Effect of the Glucagon-Like Peptide-1 Receptor Agonist Liraglutide in Male Mice fed High Carbohydrate Diets.

Glucagon-like peptide-1 receptor (GLP-1R) agonists and fibroblast growth factor 21 (FGF21) confer similar metabolic benefits. Studies report that GLP-1RA induce FGF21. Here, we investigated the mechanisms engaged by the GLP-1R agonist liraglutide to increase FGF21 levels and the metabolic relevance of liraglutide-induced FGF21. We show that liraglutide increases FGF21 levels via neuronal GLP-1R activation. We also demonstrate that lack of liver Fgf21 expression confers partial resistance to liraglutide-induced weight loss. Since FGF21 reduces carbohydrate intake, we tested whether the contribution of FGF21 to liraglutide-induced weight loss is dependent on dietary carbohydrate content. In control and liver Fgf21 knockout (Liv Fgf21 -/- ) mice fed calorically matched diets with low- (LC) or high-carbohydrate (HC) content, we found that only HC-fed Liv Fgf21 -/- mice were resistant to liraglutide-induced weight loss. Similarly, liraglutide-induced weight loss was partially impaired in Liv Fgf21 -/- mice fed a high-fat, high-sugar (HFHS) diet. Lastly, we show that loss of neuronal ß-klotho expression also diminishes liraglutide-induced weight loss in mice fed a HC or HFHS diet, indicating that FGF21 mediates liraglutide-induced weight loss via neuronal FGF21 action. Our findings support a novel role for a GLP-1R-FGF21 axis in regulating body weight in the presence of high dietary carbohydrate content.

Potent In Vitro and Ex Vivo Anti-Gonococcal Activity of the RpoB Inhibitor Corallopyronin A.

Gonorrhea remains a major global public health problem because of the high incidence of infection (estimated 82 million cases in 2020) and the emergence and spread of Neisseria gonorrhoeae strains resistant to previous and current antibiotics used to treat infections. Given the dearth of new antibiotics that are likely to enter clinical practice in the near future, there is concern that cases of untreatable gonorrhea might emerge. In response to this crisis, the World Health Organization (WHO), in partnership with the Global Antibiotic Research and Development Partnership (GARDP), has made the search for and development of new antibiotics against N. gonorrhoeae a priority. Ideally, these antibiotics should also be active against other sexually transmitted organisms, such as Chlamydia trachomatis and/or Mycoplasma genitalium, which are often found with N. gonorrhoeae as co-infections. Corallopyronin A is a potent antimicrobial that exhibits activity against Chlamydia spp. and inhibits transcription by binding to the RpoB switch region. Accordingly, we tested the effectiveness of corallopyronin A against N. gonorrhoeae. We also examined the mutation frequency and modes of potential resistance against corallopyronin A. We report that corallopyronin A has potent antimicrobial action against antibiotic-susceptible and antibiotic-resistant N. gonorrhoeae strains and could eradicate gonococcal infection of cultured, primary human cervical epithelial cells. Critically, we found that spontaneous corallopyronin A-resistant mutants of N. gonorrhoeae are exceedingly rare (≤10-10) when selected at 4× the MIC. Our results support pre-clinical studies aimed at developing corallopyronin A for gonorrheal treatment regimens. IMPORTANCE The high global incidence of gonorrhea, the lack of a protective vaccine, and the emergence of N. gonorrhoeae strains expressing resistance to currently used antibiotics demand that new treatment options be developed. Accordingly, we investigated whether corallopyronin A, an antibiotic which is effective against other pathogens, including C. trachomatis, which together with gonococci frequently cause co-infections in humans, could exert anti-gonococcal action in vitro and ex vivo, and potential resistance emergence. We propose that corallopyronin A be considered a potential future treatment option for gonorrhea because of its potent activity, low resistance development, and recent advances in scalable production.

Glucagon-like peptide-1 receptor differentially controls mossy cell activity across the dentate gyrus longitudinal axis.

Understanding the role of dentate gyrus (DG) mossy cells (MCs) in learning and memory has rapidly evolved due to increasingly precise methods for targeting MCs and for in vivo recording and activity manipulation in rodents. These studies have shown MCs are highly active in vivo, strongly remap to contextual manipulation, and that their inhibition or hyperactivation impairs pattern separation and location or context discrimination. Less well understood is how MC activity is modulated by neurohormonal mechanisms, which might differentially control the participation of MCs in cognitive functions during discrete states, such as hunger or satiety. In this study, we demonstrate that glucagon-like peptide-1 (GLP-1), a neuropeptide produced in the gut and the brain that regulates food consumption and hippocampal-dependent mnemonic function, might regulate MC function through expression of its receptor, GLP-1R. RNA-seq demonstrated that most, though not all, Glp1r in hippocampal principal neurons is expressed in MCs, and in situ hybridization revealed strong expression of Glp1r in hilar neurons. Glp1r-ires-Cre mice crossed with Ai14D reporter mice followed by co-labeling for the MC marker GluR2/3 revealed that almost all MCs in the ventral DG expressed Glp1r and that almost all Glp1r-expressing hilar neurons were MCs. However, only ~60% of dorsal DG MCs expressed Glp1r, and Glp1r was also expressed in small hilar neurons that were not MCs. Consistent with this expression pattern, peripheral administration of the GLP-1R agonist exendin-4 (5 µg/kg) increased cFos expression in ventral but not dorsal DG hilar neurons. Finally, whole-cell patch-clamp recordings from ventral MCs showed that bath application of exendin-4 (200 nM) depolarized MCs and increased action potential firing. Taken together, this study adds to known MC activity modulators a neurohormonal mechanism that may preferentially affect ventral DG physiology and may potentially be targetable by several GLP-1R pharmacotherapies already in clinical use.

Structural Basis of Peptide-Based Antimicrobial Inhibition of a Resistance-Nodulation-Cell Division Multidrug Efflux Pump.

Bacterial efflux pumps in the resistance-nodulation-cell division (RND) family of Gram-negative bacteria contribute significantly to the development of antimicrobial resistance by many pathogens. In this study, we selected the MtrD transporter protein of Neisseria gonorrhoeae as it is the sole RND pump possessed by this strictly human pathogen and can export multiple antimicrobials, including antibiotics, bile salts, detergents, dyes, and antimicrobial peptides. Using knowledge from our previously published structures of MtrD in the presence or absence of bound antibiotics as a model and the known ability of MtrCDE to export cationic antimicrobial peptides, we hypothesized that cationic peptides could be accommodated within MtrD binding sites. Furthermore, we thought that MtrD-bound peptides lacking antibacterial action could sensitize bacteria to an antibiotic normally exported by the MtrCDE efflux pump or other similar RND-type pumps possessed by different Gram-negative bacteria. We now report the identification of a novel nonantimicrobial cyclic cationic antimicrobial peptide, which we termed CASP (cationic antibiotic-sensitizing peptide). By single-particle cryo-electron microscopy, we found that CASP binds within the periplasmic cleft region of MtrD using overlapping and distinct amino acid contact sites that interact with another cyclic peptide (colistin) or a linear human cationic antimicrobial peptide derived from human LL-37. While CASP could not sensitize Neisseria gonorrhoeae to an antibiotic (novobiocin) that is a substrate for RND pumps, it could do so against multiple Gram-negative, rod-shaped bacteria. We propose that CASP (or future derivatives) could serve as an adjuvant for the antibiotic treatment of certain Gram-negative infections previously thwarted by RND transporters. IMPORTANCE RND efflux pumps can export numerous antimicrobials that enter Gram-negative bacteria, and their action can reduce the efficacy of antibiotics and provide decreased susceptibility to various host antimicrobials. Here, we identified a cationic antibiotic-sensitizing peptide (CASP) that binds within the periplasmic cleft of an RND transporter protein (MtrD) produced by Neisseria gonorrhoeae. Surprisingly, CASP was able to render rod-shaped Gram-negative bacteria, but not gonococci, susceptible to an antibiotic that is a substrate for the gonococcal MtrCDE efflux pump. CASP (or its future derivatives) could be used as an adjuvant to treat infections for which RND efflux contributes to multidrug resistance.

Transcriptional regulation of the mtrCDE efflux pump operon: importance for Neisseria gonorrhoeae antimicrobial resistance.

This review focuses on the mechanisms of transcriptional control of an important multidrug efflux pump system (MtrCDE) possessed by Neisseria gonorrhoeae, the aetiological agent of the sexually transmitted infection termed gonorrhoea. The mtrCDE operon that encodes this tripartite protein efflux pump is subject to both cis- and trans-acting transcriptional factors that negatively or positively influence expression. Critically, levels of MtrCDE can influence levels of gonococcal susceptibility to classical antibiotics, host-derived antimicrobials and various biocides. The regulatory systems that control mtrCDE can have profound influences on the capacity of gonococci to resist current and past antibiotic therapy regimens as well as virulence. The emergence, mechanisms of action and clinical significance of the transcriptional regulatory systems that impact mtrCDE expression in gonococci are reviewed here with the aim of linking bacterial antimicrobial resistance with multidrug efflux capability.

Heavy metal concentrations in the Pacific sharpnose shark Rhizoprionodon longurio from the Santa Rosalia mining zone, Baja California Sur, Mexico.

Rhizoprionodon longurio is an important commercial species captured in an area with heavy metal presence due to the mining waste from Santa Rosalia, Gulf of California, and levels of heavy metals in its muscle remain unknown. This study aimed to investigate whether contamination levels are below the limits allowed for human consumption and to prevent health damage. Concentrations of essential (Cu, Fe, Mn, and Zn) and non-essential (Ag, Cd, and Pb) trace elements were determined in fifty-seven muscle samples of R. longurio. The average concentrations of Fe > Zn > Cu > Mn > Cd > Ag did not exceed the permissible limits for human consumption established by the Mexican norm, WHO, and FAO. The mineral daily ingestion was 0.10 to 0.53 % × 100 g of muscle, and the percentage of weekly consumption was 2.5 % to <12 % concerning corporal weight. The meat from this shark can be consumed due to its low toxic potential for human health.