Actividad tejido-específica y regulación post-traduccional del receptor de mineralocorticoides.

La hormona aldosterona aumenta la reabsorción de sodio en epitelios de alta resistencia eléctrica mediante la activación del receptor de mineralocorticoides (MR), un factor de transcripción de la superfamilia de receptores nucleares. MR puede ser además activado por glucocorticoides y presenta una distribución de expresión amplia, habiendo sido implicado en distintos efectos fisiopatológicos en tejidos no epiteliales. La distribución subcelular de MR y su traslocación al núcleo inducida por ligando están controladas, entre otros mecanismos, por su interacción con la proteína de choque térmico HSP90, por la acción degradadora de cortisol de la enzima 11β-hidroxi-esteroide deshidrogenasa tipo 2 (11β-HSD2) y por modificaciones post-traduccionales del propio MR, teniendo efecto todo ello sobre la capacidad transactivadora del receptor sobre sus genes diana. En esta tesis doctoral se estudian los efectos de modificaciones post-traduccionales sobre la biología de MR, concretamente la acetilación de HSP90, SUMOilación de 11β-HSD2, y fosforilación de MR. Determinamos como estas modificaciones post-traduccionales, relacionadas directa o indirectamente con el receptor, alteran su distribución subcelular y cinética de traslocación al núcleo, modificando la respuesta a mineralocorticoides o glucocorticoides y la regulación de genes implicados en los efectos de la aldosterona. La metodología empleada en estos estudios ha sido además utilizada para evaluar la influencia de la torasemida, un diurético de asa del que se ha propuesto que también actúa como inhibidor de MR, sobre la traslocación nuclear y activación del receptor

Phosphorylation of mineralocorticoid receptor ligand binding domain impairs receptor activation and has a dominant negative effect over non-phosphorylated receptors

Post-translational modification of steroid receptors allows fine-tuning different properties of this family of proteins, including stability, activation, or interaction with co-regulators. Recently, a novel effect of phosphorylation on steroid receptor biology was described. Phosphorylation of human mineralocor ticoid receptor (MR) on Ser-843, a residue placed on the ligand binding domain, lowers affinity for agonists, producing inhibi tion of gene transactivation. We now show that MR inhibition by phosphorylation occurs even at high agonist concentration, suggesting that phosphorylation may also impair coupling between ligand binding and receptor activation. Our results demonstrate that agonists are able to induce partial nuclear translocation of MR but fail to produce transactivation due at least in part to impaired co-activator recruitment. The inhibi tory effect of phosphorylation on MR acts in a dominant-nega tive manner, effectively amplifying its functional effect on gene transactivation.info:eu-repo/semantics/publishedVersio

11β-HSD2 SUMOylation Modulates Cortisol-induced Mineralocorticoid Receptor Nuclear Translocation Independently of Effects on Transactivation

The enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) has an essential role in aldosterone target tissues, conferring aldosterone selectivity for the mineralocorticoid receptor (MR) by converting 11β-hydroxyglucocorticoids to inactive 11-ketosteroids. Congenital deficiency of 11β-HSD2 causes a form of salt-sensitive hypertension known as the syndrome of apparent mineralocorticoid excess. The disease phenotype, which ranges from mild to severe, correlates well with reduction in enzyme activity. Furthermore, polymorphisms in the 11β-HSD2 coding gene (HSD11B2) have been linked to high blood pressure and salt sensitivity, major cardiovascular risk factors. 11β-HSD2 expression is controlled by different factors such as cytokines, sex steroids, or vasopressin, but posttranslational modulation of its activity has not been explored. Analysis of 11β-HSD2 sequence revealed a consensus site for conjugation of small ubiquitin-related modifier (SUMO) peptide, a major posttranslational regulatory event in several cellular processes. Our results demonstrate that 11β-HSD2 is SUMOylated at lysine 266. Non-SUMOylatable mutant K266R showed slightly higher substrate affinity and decreased Vmax, but no effects on protein stability or subcellular localization. Despite mild changes in enzyme activity, mutant K266R was unable to prevent cortisol-dependent MR nuclear translocation. The same effect was achieved by coexpression of wild-type 11β-HSD2 with sentrin-specific protease 1, a protease that catalyzes SUMO deconjugation. In the presence of 11β-HSD2-K266R, increased nuclear MR localization did not correlate with increased response to cortisol or increased recruitment of transcriptional coregulators. Taken together, our data suggests that SUMOylation of 11β-HSD2 at residue K266 modulates cortisol-mediated MR nuclear translocation independently of effects on transactivation

Programación didáctica anual de Biología y Geología de 1º ESO y desarrollo de una unidad didáctica

Se presenta el Trabajo Fin de Máster mediante la modalidad de práctica educativa, contextualizado en el IES Tegueste, Santa Cruz de Tenerife, que incorpora una valoración de la programación didáctica del Departamento de Biología y Geología y el correspondiente análisis y reflexión de la experiencia docente adquirida durante el periodo de prácticas en el curso 2017-18. También incluye una Programación Didáctica Anual para 1º de Educación Secundaria Obligatoria (ESO), centrándola en los dos grupos de dicho nivel con los que se interactuó durante las Prácticas Externas. Se desarrolla además la Unidad Didáctica “Ni una gota de menos”, en la que se hace uso de metodologías innovadoras para favorecer la participación activa del alumnado, la adquisición de autonomía y un aprendizaje significativo.This Final Master's Project is presented through the modality of educational practice, contextualized in the IES Tegueste, Santa Cruz de Tenerife. It incorporates an assessment of the didactic program from the Department of Biology and Geology and the corresponding analysis and deliberation of the teaching experience acquired during the internship period in the 2017-18 academic year. It also includes an Annual Didactic Program for the 1st curse of “Educación Secundaria Obligatoria” (ESO), focusing on the two groups of that level which I interacted with during the External Practices. It is also developed the Didactic Unit “Ni una gota de menos”, wich makes use of innovative methodologies to promote the active participation of students, the acquisition of autonomy and meaningful learning

Phosphorylation of Mineralocorticoid Receptor Ligand Binding Domain Impairs Receptor Activation and Has a Dominant Negative Effect over Non-phosphorylated Receptors

Post-translational modification of steroid receptors allows fine-tuning different properties of this family of proteins, including stability, activation, or interaction with co-regulators. Recently, a novel effect of phosphorylation on steroid receptor biology was described. Phosphorylation of human mineralocorticoid receptor (MR) on Ser-843, a residue placed on the ligand binding domain, lowers affinity for agonists, producing inhibition of gene transactivation. We now show that MR inhibition by phosphorylation occurs even at high agonist concentration, suggesting that phosphorylation may also impair coupling between ligand binding and receptor activation. Our results demonstrate that agonists are able to induce partial nuclear translocation of MR but fail to produce transactivation due at least in part to impaired co-activator recruitment. The inhibitory effect of phosphorylation on MR acts in a dominant-negative manner, effectively amplifying its functional effect on gene transactivation