mTOR signaling in the arcuate nucleus of the hypothalamus mediates the anorectic action of estradiol

The authors dedicate this work to the bright memory of our colleague, master and friend Enrique Aguilar. The research leading to these results has received funding from Xunta de Galicia (R N: 2015-CP080 and 2016- PG057; M L: 2015-CP079), Junta de Andalucía (M T-S: P12-FQM-01943), MINECO co-funded by the FEDER Program of EU (C D: BFU2017-87721; R N: BFU2015-70664R; M T-S: BFU2014-57581-P and PIE14/0005; M L: SAF2015- 71026-R and BFU2015-70454-REDT/Adipoplast). The CiMUS is supported by the Xunta de Galicia (2016–2019, ED431G/05). CIBER Fisiopatología de la Obesidad y Nutrición is an initiative of ISCIII. A E-S is a recipient of a fellowship from MINECO (FPI/BES-2016-077439). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.Peer reviewedPublisher PD

κ-Opioid Signaling in the Lateral Hypothalamic Area Modulates Nicotine-Induced Negative Energy Balance

Several studies have reported that nicotine, the main bioactive component of tobacco, exerts a marked negative energy balance. Apart from its anorectic action, nicotine also modulates energy expenditure, by regulating brown adipose tissue (BAT) thermogenesis and white adipose tissue (WAT) browning. These effects are mainly controlled at the central level by modulation of hypothalamic neuropeptide systems and energy sensors, such as AMP-activated protein kinase (AMPK). In this study, we aimed to investigate the kappa opioid receptor (κOR)/dynorphin signaling in the modulation of nicotine’s effects on energy balance. We found that body weight loss after nicotine treatment is associated with a down-regulation of the κOR endogenous ligand dynorphin precursor and with a marked reduction in κOR signaling and the p70 S6 kinase/ribosomal protein S6 (S6K/rpS6) pathway in the lateral hypothalamic area (LHA). The inhibition of these pathways by nicotine was completely blunted in κOR deficient mice, after central pharmacological blockade of κOR, and in rodents where κOR was genetically knocked down specifically in the LHA. Moreover, κOR-mediated nicotine effects on body weight do not depend on orexin. These data unravel a new central regulatory pathway modulating nicotine’s effects on energy balanceThis research was funded from the Xunta de Galicia (R.N.: 2016-PG057; ML: 2016-PG068); Ministerio de Economía y Competitividad (MINECO) co-funded by the FEDER Program of EU (R.N.: RTI2018-099413-B-I00; C.D.: BFU2017-87721-P; M.L.: RTI2018-101840-B-I00); Atresmedia Corporación (RN and ML); Fundación BBVA (RN); “la Caixa” Foundation (ID 100010434), under the agreements LCF/PR/HR19/52160016 (R.N.) and LCF/PR/HR19/52160022 (M.L.); European Foundation for the Study of Diabetes (R.N.), ERC Synergy Grant-2019-WATCH- 810331 (R.N.) and Western Norway Regional Health Authority (Helse Vest RHF) (J.F.). P.S.-C. is the recipient of a fellowship from Xunta de Galicia (ED481B 2018/050). The CiMUS is supported by the Xunta de Galicia (2016-2019, ED431G/05). CIBER de Fisiopatología de la Obesidad y Nutrición is an initiative of ISCIIIS

Estradiol Regulates Energy Balance by Ameliorating Hypothalamic Ceramide-Induced ER Stress

Compelling evidence has shown that, besides its putative effect on the regulation of the gonadal axis, estradiol (E2) exerts a dichotomic effect on the hypothalamus to regulate food intake and energy expenditure. The anorectic effect of E2 is mainly mediated by its action on the arcuate nucleus (ARC), whereas its effects on brown adipose tissue (BAT) thermogenesis occur in the ventromedial nucleus (VMH). Here, we demonstrate that central E2 decreases hypothalamic ceramide levels and endoplasmic reticulum (ER) stress. Pharmacological or genetic blockade of ceramide synthesis and amelioration of ER stress selectively occurring in the VMH recapitulate the effect of E2, leading to increased BAT thermogenesis, weight loss, and metabolic improvement. These findings demonstrate that E2 regulation of ceramide-induced hypothalamic lipotoxicity and ER stress is an important determinant of energy balance, suggesting that dysregulation of this mechanism may underlie some changes in energy homeostasis seen in femalesThe research leading to these results has received funding from Xunta de Galicia (R.N.: 2015-CP080 and 2016-PG057; M.L.: 2015-CP079), MINECO co-funded by the FEDER Program of EU (R.N.: BFU2015-70664R; D.P.: SAF2016-77526-R; C.D.: BFU2017-87721; M.L.: SAF2015-71026-R and BFU2015-70454-REDT/Adipoplast). The CiMUS is supported by the Xunta de Galicia (2016-2019, ED431G/05). L.L.-P. is a recipient of a fellowship from Xunta de Galicia (ED481A-2016/094); E.R.-P. is a recipient of a fellowship from MINECO (BES-2015-072743); A.E.-S. is a recipient of a fellowship from MINECO (FPI/BES-2016-077439); C.R. is a recipient of a fellowship from MINECO (FPU16/04582). CIBER Fisiopatología de la Obesidad y Nutrición is an initiative of ISCIIIS

Papel de los astrocitos en la regulación de la homeostasis energética a través de AMPK

Los astrocitos se han mostrado siempre como células únicamente de sostén pero, en los últimos años, han adquirido especial relevancia por su participación en la detección y regulación de ciertos metabolitos y hormonas relacionadas con la homeostasis energética. A pesar de ello, aún se desconocen muchos de los mecanismos por los cuales los astrocitos participan en esta regulación. La proteína quinasa activada por AMP (AMPK, AMP-activated protein kinase) es un sensor celular especialmente importante en la regulación central del balance energético, sobre todo a nivel hipotalámico. Por ello, el trabajo de esta tesis fue investigar la implicación de los astrocitos en la homeostasis energética a través de AMPK. Nuestros resultados muestran que la eliminación genética de AMPKα1 en los astrocitos que expresan la proteína gliofibrilar acídica (GFAP, glial fibrillary acidic protein) provoca un aumento del peso corporal y una disminución de la termogénesis del tejido adiposo pardo (BAT, brown adipose tissue), únicamente en los ratones hembra. Además, estas hembras presentan un aumento de los niveles de aromatasa en el núcleo arcuato (ARC, arcuate nucleus) y en el núcleo ventromedial (VMH, ventromedial nucleus) del hipotálamo. Por lo tanto, estos datos muestran que los astrocitos presentan un claro dimorfismo sexual en el cual participa AMPK2023-01-2

Development of a biosensor based on a new marine luciferase fused to an affibody to assess Her2 expression in living cells

The development of new diagnostic tools in tumor pathology allows the optimization of individualized therapies in cancer patients. The functional optical image provides a unique opportunity to identify the pathophysiological characteristics of each tumor in a non-invasive way. Although fluorescent recombinant affibodies and nanobodies, capable of detecting certain membrane proteins present in tumor cells, has been described, the use of bioluminescent molecules is gaining a great impact in this field due to its high sensitivity. In this work, we characterize a new luciferase from the Metridia lucens copepod (MlLuc) and develop a novel bioluminescent recombinant affibody (MlLuc-aff) capable of recognizing the HER2 receptors that are overexpressed in breast cancer tumors. For this purpose, the thermostability and pH sensitivity of MlLuc1.1 were determined, showing no significant changes in the activity among temperatures between 4 and 70 °C, and with a maximum of brightness at pH 8.0. Furthermore, MlLuc-aff was able to accurately detect HER2 receptors expressed in the SK-BR-3 cells. Future applications of this new tracer can contribute to the early diagnosis of breast cancer patients and the assessment of the efficacy of the treatmentS

Hypothalamic astrocytic-BMAL1 regulates energy homeostasis in a sex-dependent manner

Summary: Here, we demonstrate that hypothalamic astrocytic BMAL1 computes cyclic metabolic information to optimize energetic resources in a sexually dimorphic manner. Knockdown of BMAL1 in female astrocytes leads to negative energy balance and alters basal metabolic cycles without affecting circadian locomotor activity. Thus, astrocytic BMAL1 contributes to the control of energy balance through the modulation of the metabolic rate, hepatic and white adipose tissue lipogenesis, and the activity of brown adipose tissue. Importantly, most of these alterations are specific to hypothalamic astrocytic BMAL1. Moreover, female mice with BMAL1 knockdown in astrocytes exhibited a “male-like” metabolic obese phenotype when fed a high-fat diet. Overall, our results suggest a sexually dimorphic effect of astrocytic BMAL1 on the regulation of energy homeostasis, which may be of interest in the physiopathology of obesity and related comorbidities

Genetic Targeting of GRP78 in the VMH Improves Obesity Independently of Food Intake

Recent data have demonstrated that the hypothalamic GRP78/BiP (glucose regulated protein 78 kDa/binding immunoglobulin protein) modulates brown adipose tissue (BAT) thermogenesis by acting downstream on AMP-activated protein kinase (AMPK). Herein, we aimed to investigate whether genetic over-expression of GRP78 in the ventromedial nucleus of the hypothalamus (VMH: a key site regulating thermogenesis) could ameliorate very high fat diet (vHFD)-induced obesity. Our data showed that stereotaxic treatment with adenoviruses harboring GRP78 in the VMH reduced hypothalamic endoplasmic reticulum ER stress and reversed vHFD-induced obesity. Herein, we also demonstrated that this body weight decrease was more likely associated with an increased BAT thermogenesis and browning of white adipose tissue (WAT) than to anorexia. Overall, these results indicate that the modulation of GRP78 in the VMH may be a target against obesity

BMP8 and activated brown adipose tissue in human newborns

The classical dogma states that brown adipose tissue (BAT) plays a major role in the regulation of temperature in neonates. However, although BAT has been studied in infants for more than a century, the knowledge about its physiological features at this stage of life is rather limited. This has been mainly due to the lack of appropriate investigation methods, ethically suitable for neonates. Here, we have applied non-invasive infrared thermography (IRT) to investigate neonatal BAT activity. Our data show that BAT temperature correlates with body temperature and that mild cold stimulus promotes BAT activation in newborns. Notably, a single short-term cold stimulus during the first day of life improves the body temperature adaption to a subsequent cold event. Finally, we identify that bone morphogenic protein 8B (BMP8B) is associated with the BAT thermogenic response in neonates. Overall, our data uncover key features of the setup of BAT thermogenesis in newborns

Activation of hypothalamic AMP-activated protein kinase ameliorates metabolic complications of experimental arthritis

Objective: To investigate whether thermogenesis and the hypothalamus may be involved in the physiopathology of experimental arthritis (EA). Methods: EA was induced in male Lewis rats by intradermal injection of Freund's complete adjuvant (CFA). Food intake, body weight, plasma cytokines, thermographic analysis, gene and protein expression of thermogenic markers in brown adipose tissue (BAT) and white adipose tissue (WAT), and hypothalamic AMP-activated protein kinase (AMPK) were analyzed. Virogenetic activation of hypothalamic AMPK was performed. Results: We first demonstrated that EA was associated with increased BAT thermogenesis and browning of subcutaneous WAT leading to elevated energy expenditure. Moreover, rats experiencing EA showed inhibition of hypothalamic AMPK, a canonical energy sensor modulating energy homeostasis at the central level. Notably, specific genetic activation of AMPK in the ventromedial nucleus of the hypothalamus (a key site modulating energy metabolism) reversed the effect of EA on energy balance, brown fat, and browning, as well as promoting amelioration of synovial inflammation in experimental arthritis. Conclusion: Overall, these data indicate that EA promotes a central catabolic state that can be targeted and reversed by the activation of hypothalamic AMPK. This might provide new therapeutic alternatives to treat rheumatoid arthritis (RA)–associated metabolic comorbidities, improving the overall prognosis in patients with RAThe Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CiMUS) is supported by the Xunta de Galicia (2016-2019, ED431G/05). The Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn) is an initiative of the Instituto de Salud Carlos III. Supported by the Xunta de Galicia (grants 2016-PG057 to Dr. Nogueiras, GPC IN607B2019/10 to Dr. Gualillo, and 2016-PG068 to Dr. López), the Ministerio de Economía y Competitividad (MINECO) co-funded by the FEDER Program of the European Union (grants BFU2017-90578-REDT/Adipoplast to Drs. Fernández-Real and López, RTI2018-099413-B-I00 to Dr. Nogueiras, BFU2017-87721-P to Dr. Diéguez, and RTI2018-101840-B-I00 to Dr. López), the Instituto de Salud Carlos III (grants PI15–01934 and PI18/0102224 to Dr. Fernández-Real and PI17/00409, PI20/00902, RD21/0002/0025, and RD16/0012/0014 to Dr. Gualillo), “la Caixa” Foundation (ID 100010434) (grant LCF/PR/HR19/52160022 to Dr. López), and the European Research Council (synergy grant-2019-WATCH- 810331 to Dr. Nogueiras). Dr. Seoane-Collazo's work was supported by the Xunta de Galicia (fellowship ED481B 2018/050) and the Horizon 2020 Research and Innovation Program of the European Union under the Marie Sklodowska-Curie actions. Drs. Nogueiras and López's work was supported in part by the Atresmedia Corporación. Dr. Nogueiras's work was supported in part by Fundación BBVA and the European Foundation for the Study of Diabetes. Dr. Gualillo's work was supported in part by the Horizon 2020 Research and Innovation Program of the European Union under the Marie Sklodowska-Curie actions (project no. 734899) and by the Xunta de Galicia through a research staff contract (ISCIII/SERGAS)S