Person:
Alonso Gómez, Ángel Luis

First Name

Ángel Luis

Last Name

Alonso Gómez

URI

https://hdl.handle.net/20.500.14352/74436

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Biológicas

Department

Genética, Fisiología y Microbiología

Area

Fisiología

Identifiers

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Now showing 1 - 10 of 19

Nuclear receptors (PPARs, REV-ERBs, RORs) and clock gene rhythms in goldfish (Carassius auratus) are differently regulated in hypothalamus and liver
(Frontiers in Physiology, 2022) Gómez-Boronat, Miguel; Pedro Ormeño, Nuria de; Alonso Gómez, Ángel Luis; Delgado Saavedra, María Jesús; Isorna Alonso, Esther
The circadian system is formed by a network of oscillators located in central and peripheral tissues that are tightly linked to generate rhythms in vertebrates to adapt the organism to the cyclic environmental changes. The nuclear receptors PPARs, REV-ERBs and RORs are transcription factors controlled by the circadian system that regulate, among others, a large number of genes that control metabolic processes for which they have been proposed as key genes that link metabolism and temporal homeostasis. To date it is unclear whether these nuclear receptors show circadian expression and which zeitgebers are important for their synchronization in fish. Therefore, the objective of this study was to investigate whether the two main zeitgebers (light-dark cycle and feeding time) could affect the synchronization of central (hypothalamus) and peripheral (liver) core clocks and nuclear receptors in goldfish. To this aim, three experimental groups were established: fish under a 12 h light-12 h darkness and fed at Zeitgeber Time 2; fish with the same photoperiod but randomly fed; and fish under constant darkness and fed at Circadian Time 2. After one month, clock genes and nuclear receptors expression in hypothalamus and liver and circulating glucose were studied. Clock genes displayed daily rhythms in both tissues of goldfish if the light-dark cycle was present, with shifted-acrophases of negative and positive elements, as expected for proper functioning clocks. In darkness-maintained fish hypothalamic clock genes were fully arrhythmic while the hepatic ones were still rhythmic. Among studied nuclear receptors, in the hypothalamus only nr1d1 was rhythmic and only when the light-dark cycle was present. In the liver all nuclear receptors were rhythmic when both zeitgebers were present, but only nr1d1 when one of them was removed. Plasma glucose levels showed significant rhythms in fish maintained under random fed regimen or constant darkness, with the highest levels at 1-h postprandially in all groups. Altogether these results support that hypothalamus is mainly a light-entrained-oscillator, while the liver is a food-entrained-oscillator. Moreover, nuclear receptors are revealed as clear outputs of the circadian system acting as key elements in the timekeeping of temporal homeostasis, particularly in the liver.
The liver of goldfish as a component of the circadian system: Integrating a network of signals
(General and Comparative Endocrinology, 2015) Sánchez Bretaño, Aída; Alonso Gómez, Ángel Luis; Delgado Saavedra, María Jesús; Isorna Alonso, Esther
The circadian system drives daily physiological and behavioral rhythms that allow animals to anticipate cyclic environmental changes. The discovery of the known as ‘‘clock genes’’, which are very well conserved through vertebrate phylogeny, highlighted the molecular mechanism of circadian oscillators functioning, based on transcription and translation cycles (24 h) of such clock genes. Studies in goldfish have shown that the circadian system in this species is formed by a net of oscillators distributed at central and peripheral locations, as the retina, brain, gut and liver, among others. In this work we review the existing information about the hepatic oscillator in goldfish due to its relevance in metabolism, and its key role as target of a variety of humoral signals. Different input signals modify the molecular clockwork in the liver of goldfish. Among them, there are environmental cues (photocycle and feeding regime) and different encephalic and peripheral endogenous signals (orexin, ghrelin and glucocorticoids). Per clock genes seem to be a common target for different signals. Thus, this genes family might be important for shifting the hepatic oscillator. The physiological relevance of the crosstalking between metabolic and feeding-related hormones and the hepatic clock sets the stage for the hypothesis that these hormones could act as ‘‘internal zeitgebers’’ communicating oscillators in the goldfish circadian system.
In Situ Localization and Rhythmic Expression of Ghrelin and ghs-r1 Ghrelin Receptor in the Brain and Gastrointestinal Tract of Goldfish (Carassius auratus)
(PLoS ONE, 2015) Sánchez Bretaño, Aída; Blanco Imperiali, Ayelén M.; Unniappan, Suraj; Kah, Olivier; Gueguen, Marie-M.; Bertucci, Juan I.; Alonso Gómez, Ángel Luis; Valenciano González, Ana Isabel; Isorna Alonso, Esther; Delgado, María J.
Ghrelin is a gut-brain peptide hormone, which binds to the growth hormone secretagogue receptor (GHS-R) to regulate a wide variety of biological processes in fish. Despite these prominent physiological roles, no studies have reported the anatomical distribution of preproghrelin transcripts using in situ hybridization in a non-mammalian vertebrate, and its mapping within the different encephalic areas remains unknown. Similarly, no information is available on the possible 24-h variations in the expression of preproghrelin and its receptor in any vertebrate species. The first aim of this study was to investigate the anatomical distribution of ghrelin and GHS-R1a ghrelin receptor subtype in brain and gastrointestinal tract of goldfish (Carassius auratus) using immunohistochemistry and in situ hybridization. Our second aim was to characterize possible daily variations of preproghrelin and ghs-r1 mRNA expression in central and peripheral tissues using real-time reverse transcription-quantitative PCR. Results show ghrelin expression and immunoreactivity in the gastrointestinal tract, with the most abundant signal observed in the mucosal epithelium. These are in agreement with previous findings on mucosal cells as the primary synthesizing site of ghrelin in goldfish. Ghrelin receptor was observed mainly in the hypothalamus with low expression in telencephalon, pineal and cerebellum, and in the same gastrointestinal areas as ghrelin. Daily rhythms in mRNA expression were found for preproghrelin and ghs-r1 in hypothalamus and pituitary with the acrophase occurring at nighttime. Preproghrelin, but not ghs-r1a, displayed a similar daily expression rhythm in the gastrointestinal tract with an amplitude 3-fold higher than the rest of tissues. Together, these results described for the first time in fish the mapping of preproghrelin and ghrelin receptor ghs-r1a in brain and gastrointestinal tract of goldfish, and provide the first evidence for a daily regulation of both genes expression in such locations, suggesting a possible connection between the ghrelinergic and circadian systems in teleosts.
Fatty acid sensing in the gastrointestinal tract of rainbow trout: different to mammalian model?
(International Journal of Molecular Sciences, 2023) Calo, Jessica; Comesaña, Sara; Alonso Gómez, Ángel Luis; Soengas, José ; Blanco, Ayelén
It is well established in mammals that the gastrointestinal tract (GIT) senses the luminal presence of nutrients and responds to such information by releasing signaling molecules that ultimately regulate feeding. However, gut nutrient sensing mechanisms are poorly known in fish. This research characterized fatty acid (FA) sensing mechanisms in the GIT of a fish species with great interest in aquaculture: the rainbow trout (Oncorhynchus mykiss). Main results showed that: (i) the trout GIT has mRNAs encoding numerous key FA transporters characterized in mammals (FA transporter CD36 -FAT/CD36-, FA transport protein 4 -FATP4-, and monocarboxylate transporter isoform-1 -MCT-1-) and receptors (several free FA receptor -Ffar- isoforms, and G protein-coupled receptors 84 and 119 -Gpr84 and Gpr119-), and (ii) intragastrically-administered FAs differing in their length and degree of unsaturation (i.e., medium-chain (octanoate), long-chain (oleate), long-chain polyunsaturated (α-linolenate), and short-chain (butyrate) FAs) exert a differential modulation of the gastrointestinal abundance of mRNAs encoding the identified transporters and receptors and intracellular signaling elements, as well as gastrointestinal appetite-regulatory hormone mRNAs and proteins. Together, results from this study offer the first set of evidence supporting the existence of FA sensing mechanisms n the fish GIT. Additionally, we detected several differences in FA sensing mechanisms of rainbow trout vs. mammals, which may suggest evolutionary divergence between fish and mammals.
Anatomical distribution and daily profile of gper1b gene expression in brain and peripheral structures of goldfish (Carassius auratus)
(Chronobiology International, 2015) Sánchez Bretaño, Aída; Gueguen, Marie-M.; Cano-Nicolau, Joel; Kah, Olivier; Alonso Gómez, Ángel Luis; Delgado Saavedra, María Jesús; Isorna Alonso, Esther
The functional organization of the circadian system and the location of the main circadian oscillators vary through phylogeny. Present study investigates by in situ hybridization the anatomical location of the clock gene gPer1b in forebrain and midbrain, pituitary, and in two peripheral locations, the anterior intestine and liver, in a teleost fish, the goldfish (Carassius auratus). Moreover, the daily expression profiles of this gene were also studied by quantitative Real Time-PCR. Goldfish were maintained under a 12L–12D photoperiod and fed daily at 2 h after lights were switched on. A wide distribution of gPer1b mRNA in goldfish brain and pituitary was found in telencephalon, some hypothalamic nuclei (including the homologous to mammalian SCN), habenular nucleus, optic tectum, cerebellum and torus longitudinalis. Moreover, gPer1b expression was observed, for the first time in teleosts, in the pituitary, liver and anterior intestine. Day/night differences in gper1b mRNA abundance were found by in situ hybridization, with higher signal at nighttime that correlates with the results obtained by RT-PCR, where a rhythmic gPer1b expression was found in all tissues with acrophases at the end of the night. Amplitudes of gper1b rhythms vary among tissues, being higher in liver and intestine than in the brain, maybe because different cues entrain clocks in these locations. These results support the existence of functional clocks in many central and peripheral locations in goldfish coordinated, ticking at the same time.
Characterization of Ghrelin O-Acyltransferase (GOAT) in goldfish (Carassius auratus)
(Plos ONE, 2017) Blanco Imperiali, Ayelén M.; Gómez Boronat, Miguel; Alonso Gómez, Ángel Luis; Yufa, Roman; Unniappan, Suraj; Delgado Saavedra, María Jesús; Valenciano González, Ana Isabel
Ghrelin is the only known hormone posttranslationally modified with an acylation. This modification is crucial for most of ghrelin’s physiological effects and is catalyzed by the polytopic enzyme ghrelin O-acyltransferase (GOAT). The aim of this study was to characterize GOAT in a teleost model, goldfish (Carassius auratus). First, the full-length cDNA sequence was obtained by RT-PCR and rapid amplification of cDNA ends methods. Two highly homologous cDNAs of 1491 and 1413 bp, respectively, named goat-V1 and goat-V2 were identified. Deduced protein sequences (393 and 367 amino acids, respectively) are predicted to present 11 and 9 transmembrane regions, respectively, and both contain two conserved key residues proposed to be involved in catalysis: asparagine 273 and histidine 304. RT-qPCR revealed that both forms of goat mRNAs show a similar widespread tissue distribution, with the highest expression in the gastrointestinal tract and gonads and less but considerable expression in brain, pituitary, liver and adipose tissue. Immunostaining of intestinal sections showed the presence of GOAT immunoreactive cells in the intestinal mucosa, some of which colocalize with ghrelin. Using an in vitro approach, we observed that acylated ghrelin downregulates GOAT gene and protein levels in cultured intestine in a time-dependent manner. Finally, we found a rhythmic oscillation of goat mRNA expression in the hypothalamus, pituitary and intestinal bulb of goldfish fed at midday, but not at midnight. Together, these findings report novel data characterizing GOAT, and offer new information about the ghrelinergic system in fish.
Ghrelin induces clock gene expression in the liver of goldfish in vitro via protein kinase C and protein kinase A pathways
(Journal of Experimental Biology, 2017) Sánchez Bretaño, Aída; Blanco Imperiali, Ayelén M.; Alonso Gómez, Ángel Luis; Delgado Saavedra, María Jesús; Kah, Olivier; Isorna Alonso, Esther
The liver is the most important link between the circadian system and metabolism. As a food-entrainable oscillator, the hepatic clock needs to be entrained by food-related signals. The objective of the present study was to investigate the possible role of ghrelin (an orexigenic peptide mainly synthesized in the gastrointestinal tract) as an endogenous synchronizer of the liver oscillator in teleosts. To achieve this aim, we first examined the presence of ghrelin receptors in the liver of goldfish. Then, the ghrelin regulation of clock gene expression in the goldfish liver was studied. Finally, the possible involvement of the phospholipase C/protein kinase C (PLC/PKC) and adenylate cyclase/protein kinase A (AC/PKA) intracellular signalling pathways was investigated. Ghrelin receptor transcripts, ghs-r1a, are present in the majority of goldfish hepatic cells. Ghrelin induced the mRNA expression of the positive (gbmal1a, gclock1a) and negative (gper genes) elements of the main loop of the molecular clock machinery, as well as grev-erbα (auxiliary loop) in cultured liver. These effects were blocked, at least in part, by a ghrelin antagonist. Incubation of liver with a PLC inhibitor (U73122), a PKC activator (phorbol 12-myristate 13-acetate) and a PKC inhibitor (chelerythrine chloride) demonstrated that the PLC/PKC pathway mediates such ghrelin actions. Experiments with an AC activator (forskolin) and a PKA inhibitor (H89) showed that grev-erbα regulation could be due to activation of PKA. Taken together, the present results show for the first time in vertebrates a direct action of ghrelin on hepatic clock genes and support a role for this hormone as a temporal messenger in the entrainment of liver circadian functions.
Daily Rhythms in the IGF-1 System in the Liver of Goldfish and Their Synchronization to Light/Dark Cycle and Feeding Time
(Animals, 2022) Alonso-Gómez, Aitana; Madera Sánchez, Diego; Alonso Gómez, Ángel Luis; Valenciano González, Ana Isabel; Delgado Saavedra, María Jesús
The relevance of the insulin-like growth factor-1 (IGF-1) system in several physiological processes is well-known in vertebrates, although little information about their temporal organization is available. This work aims to investigate the possible rhythmicity of the different components of the IGF-1 system (igf-1, the igf1ra and igf1rb receptors and the paralogs of its binding proteins IGFBP1 and IGFBP2) in the liver of goldfish. In addition, we also study the influence of two environmental cues, the light/dark cycle and feeding time, as zeitgebers. The hepatic igf-1 expression showed a significant daily rhythm with the acrophase prior to feeding time, which seems to be strongly dependent on both zeitgebers. Only igfbp1a-b and igfbp1b-b paralogs exhibited a robust daily rhythm of expression in the liver that persists in fish held under constant darkness or randomly fed. The hepatic expression of the two receptor subtypes did not show daily rhythms in any of the experimental conditions. Altogether these results point to the igf-1, igfbp1a-b, and igfbp1b-b as clock-controlled genes, supporting their role as putative rhythmic outputs of the hepatic oscillator, and highlight the relevance of mealtime as an external cue for the 24-h rhythmic expression of the IGF-1 system in fish.
Adaptation to the European Space of Higher Education of the subject Projects and Studies in Biology
(Edulearn 10. Conference Proceedings, 2010) Vacas, Ana María; Fonfría Díaz, José; Acosta Gallo, Belén; Alonso Gómez, Ángel Luis; Pedro Ormeño, Nuria de; Díez Sancho, Manuel; Fernández Pérez, Joaquín; López Torres, Mónica; Ramírez, Rosalía; Barrera, Alfonso; Reviriego, Mario; Gómez Chova, L.; Martí Belenguer, D.; Candel Torres, I.
The subject projects and Studies in Biology is of a professional and applied nature, as the knowledge acquired can be applied in professional practice, because the students are initiated in the implementation of a Project (Planning, Alternative Solutions, Studies, Pre-projects and Projects. The general objective of this Project involved adapting the contents of the subject to the European Space of Higher Education (EEES) by installing it in the platform WebCT (Web Course Tools), adopted by Madrid's Complutense University for its Virtual Campus. The specific objectives to be met are the following: Conceptual objectives: To introduce students to the typology of Projects. This knowledge will enable people with a degree in Biology to work in Consultancy companies and different Organisms of the Administration and to adjust to the general work market. The students are also introduced to the Spanish System of Science and Technology and to the typology of Research Projects and Projects in collaboration with industries. Procedural objectives: handling procedures for searching for updated information, both offers and calls, and innovation in regulations or in science-technology and knowledge of software programs necessary for drafting a Budget for planning and implementing projects. Attitude-related projects: Considering that people with degrees in Biology traditionally work in Teaching and Research, this subject attempts to change the attitude of students towards what could involve practicing their profession in other areas tan these. In accordance wíth these objectives, the information on the development of the subject has been organized into a series of modules through which the basic knowledge the students should avail of is expounded. Each of these modules has línks to more elaborate documents in which the amount of material is increased and its implications and relationships with other contents of the subject are indicated. The modules are organízed into classes, practica! work aimed at problem- solving, common projects, presentation and debate, and the students must draft a Pre-project for implementation using the different documents it comprises. The subject requíres evaluation of the different conceptual, procedural and attitude-related objectives, and the general adoption of an ongoing evaluation process, in which the following aspects are evaluated: - Participation in classes requiring the presence of students, refresher courses and debates. - Evaluation of the seminars: presentation and defense of projects and of exercises completed. - Directed Academíc Work (creation and defense of a Pre-project with its corresponding documents). - Correct desígn of questionnaires. - Evaluation throughout the course with objective evaluation of the contents, by means of test-types exams.
Characterization of two different melatonin binding sites in peripheral tissues of the teleost Tinca tinca
(General and Comparative Endocrinology, 2012) López Patiño, M. A.; Guijarro, A. I.; Alonso Gómez, Ángel Luis; Delgado Saavedra, María Jesús
The aim of the present study was to localize and characterize 2-iodo-melatonin ([125I]Mel) binding sites in peripheral tissues of the teleost Tinca tinca. A wide distribution of [125I]Mel binding sites in peripheral locations of the tench is found, with highest densities being measured in the heart, gills and kidney, and low density of [125I]Mel binding sites in gastrointestinal tract, spleen, liver and gonads. Saturation, kinetics, and pharmacological approaches revealed the presence of, at least, two different [125I]Mel binding sites in the tench peripheral tissues. The unique characterized subtype in the heart fulfils all the criteria for a canonical melatonin receptor belonging to MT1 family (the binding is saturable, reversible, and inhibited by GTP analogs), and gives support for the presence of a functional melatonin receptor in the heart of the tench. In contrast, kinetic and pharmacological studies in the kidney revealed the preponderance of a melatonin binding site belonging to the MT3-like receptor subtype. Moreover, the decrease of specific binding in both, heart and kidney membranes, and the decrease of affinity in the kidney, produced by the addition of a non-hydrolysable GTP analog, and sodium cations suggest the presence of Gi/o-proteins (that mediate inhibition of cAMP formation) coupled to such melatonin binding sites. Our results also point to different Gi/o-proteins involved in the underlying mechanism of melatonin binding sites activation in the kidney. Additionally, the kinetics of [125I]Mel binding in kidney membrane preparations is a highly thermosensitive process, being necessary to perform the assays at 4 °C since the equilibrium was not reached at 25 °C assay temperature. The time needed to complete association of [125I]Mel at such low temperature is only 15 s, whereas 100 s is required to displace [125I]Mel specific binding by the unlabeled melatonin in kidney membranes. Present results support previous reports on melatonin effects in the regulation of different physiological functions in teleost (as cardiovascular physiology and osmoregulation) acting through peripheral specific receptors.