Papers by Ana Karen Sotelo
Molecular and Cellular Endocrinology
Journal of Molecular Endocrinology
Growth hormone (GH) exerts major actions in cardiac growth and metabolism. Considering the import... more Growth hormone (GH) exerts major actions in cardiac growth and metabolism. Considering the important role of insulin in the heart and the well-established anti-insulin effects of GH, cardiac insulin resistance may play a role in the cardiopathology observed in acromegalic patients. As conditions of prolonged exposure to GH are associated with a concomitant increase of circulating GH, IGF1 and insulin levels, to dissect the direct effects of GH, in this study, we evaluated the activation of insulin signaling in the heart using four different models: (i) transgenic mice overexpressing GH, with chronically elevated GH, IGF1 and insulin circulating levels; (ii) liver IGF1-deficient mice, with chronically elevated GH and insulin but decreased IGF1 circulating levels; (iii) mice treated with GH for a short period of time; (iv) primary culture of rat cardiomyocytes incubated with GH. Despite the differences in the development of cardiomegaly and in the metabolic alterations among the three...
Trends in Endocrinology & Metabolism, 2021
Epidermal growth factor receptor (EGFR) signaling has a central role in the regenerative response... more Epidermal growth factor receptor (EGFR) signaling has a central role in the regenerative response of the liver upon injury and is involved in cellular transformation linked to chronic damage. Hepatic EGFR expression, trafficking, and signaling are regulated by growth hormone (GH). Chronically elevated GH levels are associated with liver cancer development and progression in mice. Studies in different in vivo experimental models indicate that EGF and GH mutually crossregulate in a complex manner. Several factors, such as the extent of exposure to supraphysiological GH levels and the pattern of GH administration, are important variables to be considered in exploring the interplay between the two hormones in connection with the progression of hepatic tumors.
Molecular and Cellular Endocrinology, 2020
Continuously elevated levels of growth hormone (GH) during life in mice are associated with hepat... more Continuously elevated levels of growth hormone (GH) during life in mice are associated with hepatomegaly due to hepatocytes hypertrophy and hyperplasia, chronic liver inflammation, elevated levels of arachidonic acid (AA) at young ages and liver tumors development at old ages. In this work, the hepatic expression of enzymes involved in AA metabolism, cPLA2α, COX1 and COX2 enzymes, was evaluated in young and old GH-transgenic mice. Mice overexpressing GH exhibited higher hepatic expression of cPLA2α, COX1 and COX2 in comparison to controls at young and old ages and in both sexes. In old mice, when tumoral and non-tumoral tissue were compared, elevated expression of COX2 was observed in tumors. In contrast, exposure to continuous lower levels of hormone for a short period affected only COX1 expression in males. Considering the role of inflammation during liver tumorigenesis, these findings support a role of alterations in AA metabolism in GH-driven liver tumorigenesis.
Biochemistry and Molecular Biology Education, 2018
Enzyme kinetics is an essential topic in undergraduate Biochemistry courses. A laboratory work th... more Enzyme kinetics is an essential topic in undergraduate Biochemistry courses. A laboratory work that covers the principal basic concepts of enzyme kinetics in steady state is presented. The alkaline phosphatase catalyzed reaction of phenylphosphate hydrolysis was studied as a model. The laboratory experience was designed to reinforce the concepts of initial velocity dependence on substrate and enzyme concentration, and to highlight the importance of the accurate determination of initial reaction rate. The laboratory work consists in two parts, in which students first determine the enzyme concentration and the time to be used in the following session to obtain the kinetic parameters (K M and V max) by non-lineal fitting of the Michaelis-Menten equation to the initial velocity dependence with substrate concentration results. The experimental methodology is robust, the cost per student is low and the equipment and reagents used are of easy access.
Molecular and Cellular Endocrinology, 2019
The renin-angiotensin system modulates insulin action. Pharmacological stimulation of angiotensin... more The renin-angiotensin system modulates insulin action. Pharmacological stimulation of angiotensin type 2 receptor (AT2R) was shown to have beneficial metabolic effects in various animal models of insulin resistance and type 2 diabetes and also to increase insulin sensitivity in wild type mice. In this study we further explored the role of the AT2R on insulin action and glucose homeostasis by investigating the glycemic profile and in vivo insulin signaling status in insulin-target tissues from both male and female AT2R knockout (KO) mice. When compared to the respective wild-type (WT) group, glycemia and insulinemia was unaltered in AT2RKO mice regardless of sex. However, female AT2RKO mice displayed decreased insulin sensitivity compared to their WT littermates. This was accompanied by a compensatory increase in adiponectinemia and with a specific attenuation of the activity of main insulin signaling components (insulin receptor, Akt and ERK1/2) in adipose tissue with no apparent alterations in insulin signaling in either liver or skeletal muscle. These parameters remained unaltered in male AT2RKO mice as compared to male WT mice. Present data show that the AT2R has a physiological role in the conservation of insulin action in female but not in male mice. Our results suggest a sexual dimorphism in the control of insulin action and glucose homeostasis by the AT2R
American Journal of Physiology-Endocrinology and Metabolism, 1995
The levels and characteristics of growth hormone (GH)-binding protein (GHBP) and the distribution... more The levels and characteristics of growth hormone (GH)-binding protein (GHBP) and the distribution of GH in peripheral circulation between the free and the bound fractions were studied in three lines of transgenic mice with various degrees of overexpression of bovine (b) GH gene. Two serum fractions bound GH specifically: one with low affinity and high capacity (GHBPI) and one with high affinity and low capacity (GHBPII). The GHBP binding capacity in normal mice (both sexes), transgenic male mice that express the metallothionein-I-hybrid bGH genes, transgenic female mice that express phosphoenolpyruvate carboxykinase (PEPCK)-bGH hybrid genes (PEPCK-bGH-1), and transgenic PEPCK-bGH-5 animals was 1.1 +/- 0.2, 2.0 +/- 0.1, 3.0 +/- 0.1, and 3.9 +/- 0.6 pmol/ml serum, respectively. The amount of GH bound to GHBP in transgenic animals vs. normal siblings was increased 1.8-, 2.5-, and 3.9-fold in these three lines. Consequently, the levels of GH-GHBP complexes in the circulation of PEPCK-bG...
Endocrine Connections, 2019
Transgenic mice overexpressing growth hormone (GH) spontaneously develop liver tumors, including ... more Transgenic mice overexpressing growth hormone (GH) spontaneously develop liver tumors, including hepatocellular carcinoma (HCC), within a year. The preneoplastic liver pathology in these mice recapitulates that observed in humans at high risk of developing hepatic cancer. Although increased expression of galectin 1 (GAL1) in liver tissue is associated with HCC aggressiveness, a link between this glycan-binding protein and hormone-related tumor development has not yet been explored. In this study, we investigated GAL1 expression during liver tumor progression in mice continuously exposed to high levels of GH. GAL1 expression was determined by Western blotting, RT-qPCR and immunohistochemistry in the liver of transgenic mice overexpressing GH. Animals of representative ages at different stages of liver pathology were studied. GAL1 expression was upregulated in the liver of GH-transgenic mice. This effect was observed at early ages, when animals displayed no signs of liver disease or m...
American Journal of Physiology-Endocrinology and Metabolism, 1997
The decay curve of labeled growth hormone (GH) in the plasma followed a three-compartment model a... more The decay curve of labeled growth hormone (GH) in the plasma followed a three-compartment model and could be described by the equation: concentration = Ae-alpha t + Be-beta t + Ce-gamma t, where A, B, and C are y-intercepts and alpha, beta, and gamma are compartments. When 125I-labeled ovine prolactin (oPRL) was injected, the decay curve could be described by the equation: concentration = Ae-alpha t + Ce-gamma t. Formation of 125I-labeled bovine-GH-binding protein (GHBP) complexes with somatogenic characteristics was demonstrated in the serum of both normal and GH transgenic mice. In contrast, 125I-oPRL was unable to form complexes of this type in any of the mice studied. Receptor-mediated liver uptake was found to be faster for PRL than for GH (5-6 min vs. 15-20 min). Liver uptake of radioactivity was significantly lower for PRL than for GH [liver to blood ratio (L/B) of 1.7 +/- 0.3 at 6 min vs. L/B of 3.7 +/- 0.6 at 20 min, respectively]. The presence of binding proteins for GH su...
International Journal of Molecular Sciences, 2017
The reliability of reverse transcription-quantitative PCR (RT-qPCR) results in gene expression st... more The reliability of reverse transcription-quantitative PCR (RT-qPCR) results in gene expression studies depends on the approaches used to account for non-biological variations. In order to find a proper normalization strategy for the study of genes related to growth hormone signaling in skeletal muscle of growing mice, nine unrelated genes were evaluated as internal controls. According to the most used algorithms-geNorm, the Comparative ∆Cq method, NormFinder and BestKeeper-GSK3B, YWHAZ, RPL13A and RN18S were found as the most stable. However, the relative expression levels of eight of the potential reference genes assessed decreased with age in cDNA samples obtained from the same amount of total RNA. In a different approach to analyze this apparent discrepancy, experiments were performed with cDNA obtained from equal amounts of purified mRNA. Since the decline was still observed, the hypothesis of an age-related change in mRNA to total RNA ratio that could account for the systematic decrease was rejected. Differences among experimental groups could be due to a substantial increase with age in highly expressed mRNAs, which would bias the quantitation of the remaining genes. Consequently, those reference genes reflecting this dilution effect, which would have been discarded considering their variable relative expression levels, arose as suitable internal controls.
Journal of Endocrinology, 2017
Transgenic mice overexpressing growth hormone (GH) show increased hepatic protein content of the ... more Transgenic mice overexpressing growth hormone (GH) show increased hepatic protein content of the epidermal growth factor receptor (EGFR), which is broadly associated with cell proliferation and oncogenesis. However, chronically elevated levels of GH result in desensitization of STAT-mediated EGF signal and similar response of ERK1/2 and AKT signaling to EGF compared to normal mice. To ascertain the mechanisms involved in GH attenuation of EGF signaling and the consequences on cell cycle promotion, phosphorylation of signaling mediators was studied at different time points after EGF stimulation, and induction of proteins involved in cell cycle progression was assessed in normal and GH-overexpressing transgenic mice. Results from kinetic studies confirmed the absence of STAT3 and 5 activation and comparable levels of ERK1/2 phosphorylation upon EGF stimulation, which was associated with diminished or similar induction of c-MYC, c-FOS, c-JUN, CYCLIN D1 and CYCLIN E in transgenic compar...
Cell cycle (Georgetown, Tex.), Jan 3, 2016
Growth hormone (GH) is a pleiotropic hormone that triggers STATs, ERK1/2 and Akt signaling, relat... more Growth hormone (GH) is a pleiotropic hormone that triggers STATs, ERK1/2 and Akt signaling, related to cell growth and proliferation. Transgenic mice overexpressing GH present increased body size, with a disproportionate liver enlargement due to hypertrophy and hyperplasia of the hepatocytes. We had described enhanced mitogenic signaling in liver of young adult transgenic mice. We now evaluate the activation of these signaling cascades during the growth period and relate them to the morphological alterations found. Signaling mediators, cell cycle regulators and transcription factors involved in cellular growth in the liver of GH-overexpressing growing mice were assessed by immunoblotting, RT-qPCR and immunohistochemistry. Hepatocyte enlargement can be seen as early as 2-weeks of age in GH-overexpressing animals, although it is more pronounced in young adults. Levels of cell cycle mediators PCNA and cyclin D1, and transcription factor c-Jun increase with age in transgenic mice with n...
Revista Andaluza De Patologia Digestiva, 2013
Introduccion y objetivos: La hernia de Spiegel es un defecto de la pared abdominal de presentacio... more Introduccion y objetivos: La hernia de Spiegel es un defecto de la pared abdominal de presentacion diversa; con diagnostico y tratamiento no estandarizados. Presentamos nuestra serie de pacientes con Hernia de Spiegel. El objetivo es analizar su evolucion historica y perfeccionar su manejo. Material y metodos: Se realiza un estudio retrospectivo de los pacientes intervenidos desde 1986 a 2011. Se analizan los factores epidemiologicos, diagnostico, tecnica quirurgica, morbilidad y recidivas. Realizamos un analisis de la evolucion historica de estas hernias, comparando el periodo 1986-98 y el 1999-2011. Resultados: SHemos tratado 64 pacientes, 24 varones y 40 mujeres, con una edad media de 54´23 anos (rango, 19-93 anos). La localizacion mas frecuente fue el lado izquierdo. Tres hernias eran bilaterales. El diagnostico clinico se hizo en el 59´37 % de los casos. La tomografia computarizada diagnostico correctamente el defecto en 13 de 16 pacientes y la ecografia en 8 de 14 pacientes. El diagnostico con pruebas de imagen se hizo en el 32´81% de los casos. Las tecnicas mas frecuentes realizadas fueron hernioplastia abierta y herniorrafia. Se efectuo cirugia de urgencias en el 26´56 % de los casos. Hubo 10 complicaciones postoperatorias. Se identificaron dos recurrencias. En el primer periodo hubo 20 pacientes vs 44 en el segundo. Edad media 60´75 anos vs 50´43 anos. Mujeres 50% vs 68´18%. Obesidad, como factor predisponente, 25% vs 40´90%. Diagnostico por imagen 30% vs 34´09%. Se uso malla por via abierta en el 20% vs 93´18%. Cirugia de urgencias 15% vs 31´81%. Tratamiento laparoscopico 0% vs 4´54%. Recidiva 5% vs 2´27%. Conclusiones: La hernia de Spiegel requiere un alto indice de sospecha debido a su sintomatologia insidiosa. En casos dudosos la tomografia computarizada es la prueba de imagen mas fiable. Debido a la alta tasa de complicaciones, su tratamiento es quirurgico. La reparacion abierta de la hernia de Spiegel, con o sin malla, consigue buenos resultados. En los ultimos trece anos se ha duplicado el numero de nuestros pacientes, la edad media ha bajado 10 anos, ha aumentado: el porcentaje de mujeres , el de obesidad, la cirugia de urgencias y el uso de malla; se han mantenido el diagnostico por imagen y las recidivas. Por ultimo destacar la incorporacion de la laparoscopia al arsenal terapeutico de la hernia de Spiegel.
Archivos Latinoamericanos De Nutricion, 2000
Archivos latinoamericanos de nutrición, 2000
The purpose of this study is to obtain a low cholesterol egg powder for the preparation of differ... more The purpose of this study is to obtain a low cholesterol egg powder for the preparation of different foods for persons whose egg consumption is restricted. Egg white and yolk mixtures prepared in different proportions were dehydrated; the following dried mixtures were obtained: A (1:1), B (2:1) and C (3:1) of egg white:yolk respectively. These mixtures were evaluated using the following parameters: proximal analysis, microbiological assay and protein quality evaluation. Physical characteristics of the powder and the sensorial tests of foods prepared with these mixtures were carried out. The fat and the cholesterol content in the mixture C were decreased by 40% and 20% respectively. The microbiological tests showed that the three mixtures were safe for human consumption. The PER of sample A (whole egg) was 3.65 and for the mixture C 3:1 egg white:yolk was 3.05. The PER of the 50:50 protein mixtures eggs white and yolk: with corn lime treated flour (HMN) were higher than that of the c...
Journal of molecular endocrinology, Jan 17, 2015
Growth hormone (GH)/STAT5 signaling is desensitized in liver of adult transgenic mice overexpress... more Growth hormone (GH)/STAT5 signaling is desensitized in liver of adult transgenic mice overexpressing GH; however, these animals present greater body size. To assess if the STAT5 pathway is active during the growth period in the liver of these animals, and how signaling modulators participate in this process, growing transgenic mice and normal siblings were evaluated. STAT5 does not respond to an acute GH-stimulus but presents higher basal phosphorylation in liver of growing GH-overexpressing mice. GH receptor and positive modulators GR and HNF1 display greater abundance in transgenic animals, supporting STAT5 activity. Negative modulators CIS and PTP1B are increased in GH-overexpressing mice. Suppressors SOCS2 and SOCS3 exhibit higher mRNA levels in transgenic mice but lower protein content, suggesting they are being degraded. Therefore, STAT5 signaling is increased in liver of GH-transgenic mice during the growth period, with a balance between positive and negative effectors result...
BioMed Research International, 2014
Lecithins, mainly composed of the phospholipids phosphatidylcholines (PC), have many different us... more Lecithins, mainly composed of the phospholipids phosphatidylcholines (PC), have many different uses in the pharmaceutical and clinical field. PC are involved in structural and biological functions as membrane trafficking processes and cellular signaling. Considering the increasing applications of lecithin-based nanosystems for the delivery of therapeutic agents, the aim of the present work was to determine the effects of phosphatidylcholine nanoparticles over breast cancer cellular proliferation and signaling. PC dispersions at 0.01 and 0.1% (w/v) prepared in buffer pH 7.0 and 5.0 were studied in the MCF-7 breast cancer cell line. Neutral 0.1% PC-derived nanoparticles induced the activation of the MEK-ERK1/2 pathway, increased cell viability and induced a 1.2 fold raise in proliferation. These biological effects correlated with the increase of epidermal growth factor receptor (EGFR) content and its altered cellular localization. Results suggest that nanoparticles derived from PC dis...
Contemporary Aspects of Endocrinology, 2011
This chapter will describe the effects of long term exposure to growth hormone (GH) at the molecu... more This chapter will describe the effects of long term exposure to growth hormone (GH) at the molecular level in the liver. Expression and activation of intermediates involved in GH-induced signaling were analyzed in transgenic mice overexpressing GH, as well as the influence of chronically elevated GH levels over Amend: epidermal growth factor receptor (EGFR) signaling. Several signaling mediators involved in cellular proliferation, survival and migration are altered in the liver of GH-transgenic mice. The molecular mechanisms underlying the prooncogenic pathology induced by prolonged exposure to elevated GH levels will be discussed. 1.1 Physiological actions of GH Growth hormone (GH), also known as somatotropin, is the main regulator of postnatal body growth, but its actions are not limited to corporal stature. GH has important metabolic functions on carbohydrate, lipid and protein metabolism, as well as on tissue maintenance and repair, cardiac and immune function, mental agility and ageing. It exerts its actions both directly, and by means of endocrine and paracrine insulin-like growth factor (IGF) 1. At the cellular level, GH modulates proliferation, differentiation, motility and apoptosis. GH secretion: Growth hormone, part of the somatotropic axis, is mainly synthesized in somatotroph cells from the anterior pituitary. Growth hormone secretion is regulated centrally, through the hypothalamic-portal circulation, by hypothalamic peptides: its synthesis and release are promoted by growth-hormone releasing hormone (GHRH) and inhibited by somatostatin, and it is also stimulated by stomach-derived ghrelin. Stress, exercise, malnutrition, and anorexia also promote its secretion. By means of negative feedback, GH inhibits its own secretion: in the short central loop, GH acts on somatotroph cells to generate IGF1 locally, that in turn inhibits the cell; and it acts at the hypothalamic level to inhibit GHRH synthesis and release and to stimulate both synthesis and release of somatostatin. In the long peripheral loop, GH acts on the liver to generate most of circulating IGF1, which inhibits GH secretion by a dual mechanism: direct inhibition of the somatotrophs and stimulation of somatostatin release. GH is also produced locally in many tissues, acting in an autocrine and www.intechopen.com Contemporary Aspects of Endocrinology 74 paracrine fashion. Central cholinergic stimulation increases the release of GH reducing the secretion of somatostatin. Glucocorticoids and metabolic substrates also affect GH secretion; treatment with glucocorticoids inhibits its release while fasting states with hypoglycemia, low circulating free fatty acids, and high circulating amino acid concentrations stimulate it. GH secretion presents sexual dimorphism: the frequency of pulses is higher in females. The difference is most striking in rats, where secretion profile in males is characterized by high amplitude pulses every 3-4 h, with almost non-detectable values between pulses. Female rats, on the contrary, have more frequent lower amplitude pulses, and thus present baseline GH levels (Waxman & Frank, 2000). Humans, on the other hand, present higher values at night, during the first hours of sleep, and lower values in the early morning. GH secretory pattern conditions the sexually dimorphic gene expression in the liver, particularly of proteins involved in steroid and drug metabolism. GH secretion presents age-dependency: circulating GH levels progressively rise during childhood, to achieve a maximum towards the end of adolescence in humans, and slowly diminish thereafter. By the sixth decade of life, they are only 20% of maximum (Turyn & Sotelo, 2004). GH function: Somatic growth: GH acts directly on bone and indirectly, through endocrine hepatic derived IGF1, as well as the locally produced factor. These growth promoting peptides act on the epiphyseal cartilage, inducing chondrocyte proliferation, which leads to longitudinal skeletal growth (Tritos & Biller, 2009). Longitudinal growth ceases when the epiphyses of the long bones fuse to the diaphyses. Oversecretion before this instance results in gigantism, whereas oversecretion afterwards results in acromegaly, characterized by abnormal growth of hands and feet, and roughening of the facial features: protrusion of brow and lower jaw, and nose enlargement. Lack of GH or GHR in humans results in severe short stature, reduced muscle mass, increased fat storage, decreased cortical bone mineral density and decreased fertility in females (Lichanska & Waters., 2008a). In animals, basically the same growth outcome can be observed, either in spontaneous mutants or in genetically engineered models. Notably, mice lacking GH or GHR live longer than their littermates (Bartke & Brown-Borg, 2004). Besides its effects on skeletal growth, GH regulates body composition, increasing muscle mass and decreasing adipose content. The relationship between GH status and body composition is evidenced in patients and animal models lacking GH, which become obese. In humans, symptoms of GH deficiency resemble those of ageing, when GH levels decline: loss of muscular mass and tone, loss of bone mineral density, loss of strength, abdominal obesity (Perrini et al., 2010). Metabolic actions: GH has important metabolic actions on lipid and carbohydrate metabolism. It presents both insulin-like and insulin-antagonistic actions, presumably the first are IGF1-mediated while the latter are directly exerted by the hormone, since the effects of IGF1 on lipolysis and gluconeogenesis are contrary to those of GH (Kaplan & Cohen, 2010). GH exerts lipolytic effects, principally at the visceral adipose tissue, resulting in an increase of circulating free fatty acids, by increasing adipose tissue hormone-sensitive lipase activity; at the same time, it inhibits glucose uptake in adipose tissue. On the other hand, in liver GH promotes triglyceride (TG) uptake and storage, and in skeletal muscle it induces TG uptake and utilization. GH also presents anabolic actions on protein metabolism, since it stimulates protein synthesis and inhibits its proteolysis (Vijayakumar et al., 2010).
Endocrine …, 2012
Growth hormone (GH) is involved in body growth and metabolism. This hormone is used for the treat... more Growth hormone (GH) is involved in body growth and metabolism. This hormone is used for the treatment of various clinical conditions and is administrated subcutaneously once daily or 3 times a week. The chronic use of GH has side effects; among them, the increase in ...
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Papers by Ana Karen Sotelo