Testosterone activates glucose metabolism through AMPK and androgen signaling in cardiomyocyte hypertrophy

Background: Testosterone regulates nutrient and energy balance to maintain protein synthesis and metabolism in cardiomyocytes, but supraphysiological concentrations induce cardiac hypertrophy. Previously, we determined that testosterone increased glucose uptake—via AMP-activated protein kinase (AMPK)—after acute treatment in cardiomyocytes. However, whether elevated glucose uptake is involved in long-term changes of glucose metabolism or is required during cardiomyocyte growth remained unknown. In this study, we hypothesized that glucose uptake and glycolysis increase in testosterone-treated cardiomyocytes through AMPK and androgen receptor (AR). Methods: Cultured cardiomyocytes were stimulated with 100 nM testosterone for 24 h, and hypertrophy was verified by increased cell size and mRNA levels of β-myosin heavy chain (β-mhc). Glucose uptake was assessed by 2-NBDG. Glycolysis and glycolytic capacity were determined by measuring extracellular acidification rate (ECAR). Results: Testosterone induced cardiomyocyte hypertrophy that was accompanied by increased glucose uptake, glycolysis enhancement and upregulated mRNA expression of hexokinase 2. In addition, testosterone increased AMPK phosphorylation (Thr172), while inhibition of both AMPK and AR blocked glycolysis and cardiomyocyte hypertrophy induced by testosterone. Moreover, testosterone supplementation in adult male rats by 5 weeks induced cardiac hypertrophy and upregulated β-mhc, Hk2 and Pfk2 mRNA levels. Conclusion: These results indicate that testosterone stimulates glucose metabolism by activation of AMPK and AR signaling which are critical to induce cardiomyocyte hypertrophy.Fil: Troncoso, Mayarling Francisca. Universidad de Chile; ChileFil: Pavez, Mario. Universidad de Chile; ChileFil: Wilson Rodriguez, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina. Universidad de Chile; ChileFil: Lagos, Daniel. Universidad de Chile; ChileFil: Duran, Javier. Universidad de Chile; ChileFil: Ramos, Sebastián. Universidad de Chile; ChileFil: Barrientos, Genaro. Universidad de Chile; ChileFil: Silva, Patricio. Universidad Central de Chile; ChileFil: Llanos, Paola. Universidad de Chile; ChileFil: Basualto Alarcón, Carla. Universidad de Chile; Chile. Universidad de Aysén; ChileFil: Westenbrink, B. Daan. University of Groningen; Países BajosFil: Lavandero, Sergio. Universidad de Chile; Chile. Texas A&M University; Estados UnidosFil: Estrada, Manuel. Universidad de Chile; Chil

In vitro and in vivo effects of PDGF-BB delivery strategies on tendon healing: a review

To promote and support tendon healing, one viable strategy is the use or administration of growth factors at the wound/rupture site. Platelet derived growth factor-BB (PDGF-BB), together with other growth factors, is secreted by platelets after injury. PDGF-BB promotes mitogenesis and angiogenesis, which could accelerate tendon healing. Therefore, in vitro studies with PDGF-BB have been performed to determine its effect on tenocytes and tenoblasts. Moreover, accurate and sophisticated drug delivery devices, aiming for a sustained release of PDGF-BB, have been developed, either by using heparin-binding and fibrin-based matrices or different electrospinning techniques. In this review, the structure and composition, as well as the healing process of tendons, are described. Part A deals with in vitro studies. They focus on the multiple effects evoked by PDGF-BB on the cellular level. Moreover, they address strategies for the sustained delivery of PDGF-BB. Part B focuses on animal models used to test different delivery strategies for PDGF-BB, in the context of tendon reconstruction. These studies showed that dosage and timing of PDGF-BB application are the most important factors for deciding which delivery device should be applied for a specific tendon laceration

Sodium-glucose co-transporter 2 inhibition with empagliflozin improves cardiac function in non-diabetic rats with left ventricular dysfunction after myocardial infarction

AIMS: Sodium-glucose co-transporter 2 (SGLT2) inhibition reduces heart failure hospitalizations in patients with diabetes, irrespective of glycaemic control. We examined the effect of SGLT2 inhibition with empagliflozin (EMPA) on cardiac function in non-diabetic rats with left ventricular (LV) dysfunction after myocardial infarction (MI). METHODS AND RESULTS: Non-diabetic male Sprague-Dawley rats underwent permanent coronary artery ligation to induce MI, or sham surgery. Rats received chow containing EMPA that resulted in an average daily intake of 30 mg/kg/day or control chow, starting before surgery (EMPA-early) or 2 weeks after surgery (EMPA-late). Cardiac function was assessed using echocardiography and histological and molecular markers of cardiac remodelling and metabolism were assessed in the left ventricle. Renal function was assessed in metabolic cages. EMPA increased urine production by two-fold without affecting creatinine clearance and serum electrolytes. EMPA did not influence MI size, but LV ejection fraction (LVEF) was significantly higher in the EMPA-early and EMPA-late treated MI groups compared to the MI group treated with vehicle (LVEF 54%, 52% and 43%, respectively, all P < 0.05). EMPA also attenuated cardiomyocyte hypertrophy, diminished interstitial fibrosis and reduced myocardial oxidative stress. EMPA treatment reduced mitochondrial DNA damage and stimulated mitochondrial biogenesis, which was associated with the normalization of myocardial uptake and oxidation of glucose and fatty acids. EMPA increased circulating ketone levels as well as myocardial expression of the ketone body transporter and two critical ketogenic enzymes, indicating that myocardial utilization of ketone bodies was increased. Together these metabolic changes were associated with an increase in cardiac ATP production. CONCLUSION: Empagliflozin favourably affects cardiac function and remodelling in non-diabetic rats with LV dysfunction after MI, associated with substantial improvements in cardiac metabolism and cardiac ATP production. Importantly, it did so without renal adverse effects. Our data suggest that EMPA might be of benefit in heart failure patients without diabetes

Selenoprotein dio2 is a regulator of mitochondrial function, morphology and uprmt in human cardiomyocytes

Members of the fetal-gene-program may act as regulatory components to impede deleterious events occurring with cardiac remodeling, and constitute potential novel therapeutic heart failure (HF) targets. Mitochondrial energy derangements occur both during early fetal development and in patients with HF. Here we aim to elucidate the role of DIO2, a member of the fetal-gene-program, in pluripotent stem cell (PSC)-derived human cardiomyocytes and on mitochondrial dynamics and energetics, specifically. RNA sequencing and pathway enrichment analysis was performed on mouse cardiac tissue at different time points during development, adult age, and ischemia-induced HF. To determine the function of DIO2 in cardiomyocytes, a stable human hPSC-line with a DIO2 knockdown was made using a short harpin sequence. Firstly, we showed the selenoprotein, type II deiodinase (DIO2): the enzyme responsible for the tissue-specific conversion of inactive (T4) into active thyroid hormone (T3), to be a member of the fetal-gene-program. Secondly, silencing DIO2 resulted in an increased reactive oxygen species, impaired activation of the mitochondrial unfolded protein response, severely impaired mitochondrial respiration and reduced cellular viability. Microscopical 3D reconstruction of the mitochondrial network displayed substantial mitochondrial fragmentation. Summarizing, we identified DIO2 to be a member of the fetal-gene-program and as a key regulator of mitochondrial performance in human cardiomyocytes. Our results suggest a key position of human DIO2 as a regulator of mitochondrial function in human cardiomyocytes

Research on pinch plasma focus devices of hundred of kilojoules to tens of joules

At present the Plasma Physics and Plasma Technology Group of the Comisión Chilena de Energía Nuclear (CCHEN) has the experimental facilities in order to study fast dense transient discharges in a wide range of energy and current, namely: I) energy from hundred of kilojoules to tens of joules, II) current from megaamperes to tens of kiloamperes. Also several diagnostics have been implemented. An overview of the work being carried out on dense pinch plasma focus discharges at the Comisión Chilena de Energía Nuclear is presented. The plasma energy density and scaling laws for the neutron yield are discussed. Possible applications of the radiation emitted are also discussed

Gain-of-function mutation in ubiquitin ligase KLHL24 causes desmin degradation and dilatation in hiPSC-derived engineered heart tissues

The start codon c.1A>G mutation in KLHL24, encoding ubiquitin ligase KLHL24, results in the loss of 28 N-terminal amino acids (KLHL24-ΔN28) by skipping the initial start codon. In skin, KLHL24-ΔN28 leads to gain of function, excessively targeting intermediate filament keratin-14 for proteasomal degradation and ultimately causing epidermolysis bullosa simplex (EBS). The majority of patients with EBS are also diagnosed with dilated cardiomyopathy (DCM), but the pathological mechanism in the heart is unknown. As desmin is the cardiac homolog of keratin-14, we hypothesized that KLHL24-ΔN28 leads to excessive degradation of desmin, resulting in DCM. Dynamically loaded engineered heart tissues (dyn-EHTs) were generated from human-induced pluripotent stem cell–derived (hiPSC-derived) cardiomyocytes from 2 patients and 3 nonfamilial controls. Ten-fold lower desmin protein levels were observed in patient-derived dyn-EHTs, in line with diminished desmin levels detected in patients’ explanted heart. This was accompanied by tissue dilatation, impaired mitochondrial function, decreased force values, and increased cardiomyocyte stress. HEK293 transfection studies confirmed KLHL24-mediated desmin degradation. KLHL24 RNA interference or direct desmin overexpression recovered desmin protein levels, restoring morphology and function in patient-derived dyn-EHTs. To conclude, presence of KLHL24-ΔN28 in cardiomyocytes leads to excessive degradation of desmin, affecting tissue morphology and function, which can be prevented by restoring desmin protein levels

The erythropoietin receptor expressed in skeletal muscle is essential for mitochondrial biogenesis and physiological exercise

Erythropoietin (EPO) is a haematopoietic hormone that regulates erythropoiesis, but the EPO-receptor (EpoR) is also expressed in non-haematopoietic tissues. Stimulation of the EpoR in cardiac and skeletal muscle provides protection from various forms of pathological stress, but its relevance for normal muscle physiology remains unclear. We aimed to determine the contribution of the tissue-specific EpoR to exercise-induced remodelling of cardiac and skeletal muscle. Baseline phenotyping was performed on left ventricle and m. gastrocnemius of mice that only express the EpoR in haematopoietic tissues (EpoR-tKO). Subsequently, mice were caged in the presence or absence of a running wheel for 4 weeks and exercise performance, cardiac function and histological and molecular markers for physiological adaptation were assessed. While gross morphology of both muscles was normal in EpoR-tKO mice, mitochondrial content in skeletal muscle was decreased by 50%, associated with similar reductions in mitochondrial biogenesis, while mitophagy was unaltered. When subjected to exercise, EpoR-tKO mice ran slower and covered less distance than wild-type (WT) mice (5.5 ± 0.6 vs. 8.0 ± 0.4 km/day, p < 0.01). The impaired exercise performance was paralleled by reductions in myocyte growth and angiogenesis in both muscle types. Our findings indicate that the endogenous EPO-EpoR system controls mitochondrial biogenesis in skeletal muscle. The reductions in mitochondrial content were associated with reduced exercise capacity in response to voluntary exercise, supporting a critical role for the extra-haematopoietic EpoR in exercise performance. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00424-021-02577-4

ATPase Inhibitory Factor-1 Disrupts Mitochondrial Ca2+ Handling and Promotes Pathological Cardiac Hypertrophy through CaMKIIδ

ATPase inhibitory factor-1 (IF1) preserves cellular ATP under conditions of respiratory collapse, yet the function of IF1 under normal respiring conditions is unresolved. We tested the hypothesis that IF1 promotes mitochondrial dysfunction and pathological cardiomyocyte hypertrophy in the context of heart failure (HF). Methods and results: Cardiac expression of IF1 was increased in mice and in humans with HF, downstream of neurohumoral signaling pathways and in patterns that resembled the fetal-like gene program. Adenoviral expression of wild-type IF1 in primary cardiomyocytes resulted in pathological hypertrophy and metabolic remodeling as evidenced by enhanced mitochondrial oxidative stress, reduced mitochondrial respiratory capacity, and the augmentation of extramitochondrial glycolysis. Similar perturbations were observed with an IF1 mutant incapable of binding to ATP synthase (E55A mutation), an indication that these effects occurred independent of binding to ATP synthase. Instead, IF1 promoted mitochondrial fragmentation and compromised mitochondrial Ca2+ handling, which resulted in sarcoplasmic reticulum Ca2+ overloading. The effects of IF1 on Ca2+ handling were associated with the cytosolic activation of calcium-calmodulin kinase II (CaMKII) and inhibition of CaMKII or co-expression of catalytically dead CaMKIIδC was sufficient to prevent IF1 induced pathological hypertrophy. Conclusions: IF1 represents a novel member of the fetal-like gene program that contributes to mitochondrial dysfunction and pathological cardiac remodeling in HF. Furthermore, we present evidence for a novel, ATP-synthase-independent, role for IF1 in mitochondrial Ca2+ handling and mitochondrial-to-nuclear crosstalk involving CaMKII

Estudio de la contaminación por plomo en suelos de una planta de reciclaje de baterías cerrada en Freire, IX Región.

Freire es una comuna de la Provincia de Cautín, IX Región de Chile. Hace unos 30 años operaba en dicha comuna una planta industrial de recuperación de materiales de baterías en desuso, proceso que está asociado a la generación de residuos con plomo. En el año 1996 se dispuso el cierre de la planta, sin embargo, tal acción no se realizó bajo los criterios ambientales actuales. Por esta razón, se sospecha que los suelos de la planta puedan contener altos niveles de plomo, generando un riesgo potencial para la salud de la población y el medio ambiente. Se realizó una campaña de muestreo que consistió en la recolección de 18 muestras simples de suelo a una profundidad de 0-20 cm. el 4 de Octubre de 2016. Se determinó 9 puntos de muestreo dentro del sitio de la planta y otros 8 en los alrededores del mismo correspondientes a los niveles basales o naturales. Los análisis fueron realizados en el Laboratorio de Química Ambiental del Centro Nacional del Medio Ambiente (CENMA). Se determinaron las características físico-químicas de las muestras de suelo: pH (método potenciométrico), humedad (pérdida de peso por evaporación) y materia orgánica (pérdida de peso por calcinación), y las concentraciones de plomo mediante espectrometría de plasma acoplado inductivamente con detector óptico (ICP-OES). No se encontró asociaciones estadísticamente significativas entre las variables pH, humedad y materia orgánica en relación con las concentraciones de plomo. Las concentraciones de plomo en el sitio superaban ampliamente los niveles basales y la normativa de referencia elegida (400 [mg/Kg] EPA). Para evaluar si estas concentraciones suponían un riesgo para la población se utilizó el software IEUBK, el cual permite estimar los niveles de plomo sanguíneo en niños expuestos a plomo medio ambiental. Las concentraciones fueron lo suficientemente altas como para sobrepasar el valor máximo de 30 [μg/dL] de plomo en la sangre para el cual el modelo fue calibrado y validado empíricamente. Para determinar si el plomo tenía la capacidad de alcanzar cuerpos de agua adyacentes al sitio, se llevaron a cabo test de lixiviación (TCLP: método 1311 EPA). Las muestras de suelo se colocaron en contacto con una solución de ácido a pH 4,93 por 18 horas a 23°C, posteriormente, fueron filtradas y se midió la concentración de viii plomo en los filtrados. Las concentraciones de plomo lixiviado por 4 de las 9 muestras fueron superiores a la Concentración Máxima Permisible (5 [mg/L] de acuerdo al DS 148), por lo que se les clasifica como residuos peligrosos y no deben permanecer en el sitio bajo las condiciones actuales. Considerando el riesgo potencial al que está expuesto la población, se proponen medidas tanto a corto como largo plazo. Las primeras, incluyen informar a las autoridades y comunidades, cercar el sitio e instalar letreros de advertencia; mientras que en el caso de las segundas, se plantean 4 alternativas de mitigación con sus respectivas ventajas y desventajas: solidificación/estabilización, lavado de suelo/lixiviación ácida, excavación del suelo y disposición fuera del sitio, y cobertura de suelo.Freire is a commune located at the Province of Cautín, IX Region of Chile. About 30 years ago, an industrial plant that recovered disused battery materials operated in this commune, process which is associated with the generation of lead waste. In 1996, the plant was stipulated to be closed, however, such action was not carried out under the current environmental criteria. For this reason, it is suspected that the soils of the industrial plant may contain high levels of lead, generating a potential risk to the health of the population and the environment. A sampling campaign was carried out on October 4, 2016, and it consisted in the collection of 18 simple soil samples at a depth of 0-20 cm. 9 sampling points were selected in the industrial plant site and 8 in the surrounding area, corresponding to the background/natural levels. The analyzes were carried out in the Environmental Chemistry Laboratory of the Environment National Center (CENMA). The physico-chemical characteristics of the soil samples were determined: pH (potentiometric method), moisture (loss of weight by evaporation) and organic matter (loss of weight by calcination). Lead concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). No statistically significant associations were found between pH, moisture and organic matter in relation to lead concentrations. Lead concentrations at the site far exceeded background levels and the chosen reference standard (400 [mg/kg] EPA). IEUBK software was used to evaluate whether these concentrations pose a risk to the population, allowing the estimation of blood lead levels in children exposed to environmental lead. Concentrations were high enough to exceed the maximum value of 30 [μg/dL] of lead in blood for which the model was calibrated and empirically validated. To determine if lead had the capability to reach water bodies adjacent to the industrial plant site, leaching tests (TCLP: method 1311 EPA) were conducted. Soil samples were placed in contact with an acid solution of pH 4.93 for 18 hours at 23°C, after which they were filtered and the concentration of lead in the filtrates was measured. Lead concentrations leached by 4 of the 9 samples were higher than the Maximum Permissible Concentration (5 [mg/L] according to DS 148), therefore, they x were classified as hazardous waste and should not remain in the site under current conditions. Considering the potential risk to which the population is exposed, both short and long term measures are proposed. Short-term measures include informing authorities and communities, fencing the site and installing warning signs. As regards long-term measures, 4 mitigation alternatives are proposed with their respective advantages and disadvantages: solidification/stabilization, soil washing/acid leaching, soil excavation and off-site disposal, and soil-capping