Celo inter manus pontificum tradidit spiritum. The ideology surrounding royal deaths in the light of the Latin castilian-leonese chronicles (twelfth and thirteenth centuries)

The death of a king in the medieval chronicles is an incomparable historiographical locus from which to examine this phenomenon. Historiographical texts written at the Castilian-Leonese court during the twelfth century and first half of the thirteenth century, in addition to offering first hand information on royal deaths and the accompanying ceremonies and funeral rites, fully reflect the ideological conceptions and propagandistic constructs surrounding such exceptional events, as will be seen in the first section of this article. In a second section, attention will be paid to the narrative and literary treatment given to the death of a king, as on a formal plane this is also considered to be an event of notable importance.This article is framed in the Migravit and Sepultus Research Projects financed by the Ministerio de Ciencia, Innovación y Universidades and the Casa de Velázquez [ref.: HAR2016-74846-P]

Identificación bioquímica, genética y funcional de genes implicados en la potencialidad de células germinales

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Bioquímica. Fecha de lectura: 13-01-2017La obtención de células troncales pluripotentes inducidas ha supuesto un gran avance científico. Sin embargo, la baja eficiencia de su obtención y la falta de conocimiento acerca de los fundamentos moleculares implicados en la adquisición de pluripotencia han retrasado la aplicación de esta tecnología a la práctica clínica. Para esclarecer los mecanismos implicados en la reprogramación celular, el presente trabajo utilizó células germinales primordiales (PGCs) de ratón, que conservan una estrecha relación con la pluripotencia. En primer lugar, las PGCs expresan factores relacionados con la pluripotencia, como Oct4, Sox2, Nanog y Lin28. Además, las PGCs, que normalmente dan lugar únicamente a los gametos, son capaces de reprogramarse hacía células germinales embrionarias (EGCs), de tipo pluripotente, al ser cultivadas en presencia de bFGF o de tricostatina A. Finalmente, al ser cultivadas en condiciones de hipoxia, las PGCs dan lugar a células reprogramadas capaces de diferenciarse in vitro hacia las tres hojas embrionarias y de integrarse en mórulas en desarrollo. Sin embargo, las células generadas por exposición a hipoxia no son capaces de expandirse en cultivo, probablemente por su negatividad para Klf4 y c-Myc. Los resultados recogidos en esta tesis doctoral muestran que tanto el metabolismo energético como la autofagia o la modificación epigenética entre otros procesos, intervienen en la reprogramación de las PGCs y son capaces de inducirla mediante el uso de factores solubles. Las células obtenidas mediante el uso de estos factores reprogramadores son capaces de dar lugar a las 3 hojas embrionarias in vitro. Sin embargo, las células obtenidas son negativas para Klf4 y/o c-Myc y no pueden mantenerse en cultivo a largo plazo. La inducción de pluripotencia mediante los diversos compuestos reprogramadores converge en un pico esporádico de expresión de HIF1α y en la pérdida progresiva de la expresión de HIF2α. Además, se aprecia un mayor número de mitocondrias inactivas y una desregulación en los niveles de Oct4 dependiente de HIF. La alteración del metabolismo energético y del estado epigenético aumenta la capacidad proliferativa de las células reprogramadas, que muestran positividad para c-Myc, pero no para Klf4, y que igualmente no alcanzan la capacidad de autorrenovación indefinida. En conclusión, la reprogramación de PGCs implica una reestructuración celular, metabólica y epigenética que converge en la expresión temporal de HIF1α y en la pérdida de HIF2α, lo cual desemboca en la alteración de los niveles de Oct4 y en la reprogramación metabólica hacia un perfil glicolítico. Las células reprogramadas obtenidas no alcanzan un fenotipo reprogramado completo, ya que aunque presentan capacidad pluripotente dando lugar a células de las tres hojas embrionarias, no poseen una capacidad plena de autorrenovación.The generation of induced pluripotent stem cells represents a major scientific breakthrough. However, the low efficiency of their derivation and the lack of understanding of the molecular pathways involved in the acquisition of pluripotency have delayed the application of this technology into clinical practice. In order to unfold the mechanisms involved in cell reprogramming, this study utilized mouse primordial germ cells (PGCs), which indirectly store pluripotency. Firstly, PGCs express transcription factors associated to pluripotency, such as Oct4, Sox2, Nanog and Lin28. Secondly, PGCs, which normally only give rise to gametes, are able to reprogram towards pluripotent embryonic germ cells (EGCs) when cultured with bFGF and trichostatin A. Also, when cultured under hypoxic conditions, PGCs reprogram into cells able to differentiate in vitro towards the three germ layers and to integrate in vivo into developing morulae. However, these hypoxiaderived cells are not able to expand indefinitely in vitro, probably because of their lack of expression of Klf4 and c-Myc. Results included in this study show that energetic metabolism, autophagy or epigenetic state among others intervene in PGCs reprogramming and are able to induce it using soluble factors. Cells derived using these reprogramming factors are able to differentiate into the three germ layers in vitro. However, these reprogrammed cells are also Klf4 and/or c-Myc-negative and cannot be maintained indefinitely in culture. Induction of pluripotency using these reprogramming factors shares some common features: a peak of expression of HIF1α and the progressive loss of HIF2α. In addition, a larger number of inactive mitochondria and a HIFdependent Oct4 levels deregulation are observed. Also, alteration of energetic metabolism and epigenetic state enhance the proliferative capacity of reprogrammed cells, which become c- Myc-positive but remain Klf4-negative and do not acquire full self-renewal capacity. In conclusion, PGCs reprogramming involves cell, metabolic and epigenetic rearrangements, which lead to temporary expression of HIF1α, loss of HIF2α, Oct4 deregulation and metabolic reprogramming towards a glycolytic profile. Reprogrammed cells do not reach a complete reprogrammed phenotype, since they do not show a full self-renewal capacity although they are able to give rise to cells of the three germ layers

Primordial Germ Cell Reprogramming

Primordial germ cells (PGCs) are the embryonic precursors of the gametes. Thus, they are unipotent cells. However, PGCs share some common features with pluripotent stem cells. Among them, PGCs show alkaline phosphatase activity and express stage-specific embryonic antigens and pluripotency factors Lin28, Oct4, Sox2, and Nanog. Under specific conditions, they undergo spontaneous reprogramming in vivo. Moreover, they can be easily reprogrammed in vitro into pluripotent embryonic germ cells (EGCs) by culturing them in the presence of basic fibroblast growth factor or the epigenetic modulator trichostatin A. Previous work in our laboratory has also proven that hypoxia alone can reprogram PGCs into hypoxia-induced embryonic germ-like cells, which have a pluripotent phenotype but which do not show self-renewal capacity. Therefore, PGCs are an interesting model to further comprehensively understand the process of cell reprogramming. This chapter reviews various methods to achieve PGC reprogramming, as well as the molecular pathways involved. We focus on soluble factors and genetic strategies to obtain pluripotent cells from PGCs. Special emphasis will be given to factors implied in energetic metabolism, epigenetics, and cell signaling transduction, both in vitro and in vivo

Cell-cycle exit and stem cell differentiation are coupled through regulation of mitochondrial activity in the Drosophila testis

Summary Whereas stem and progenitor cells proliferate to maintain tissue homeostasis, fully differentiated cells exit the cell cycle. How cell identity and cell-cycle state are coordinated during differentiation is still poorly understood. The Drosophila testis niche supports germline stem cells and somatic cyst stem cells (CySCs). CySCs give rise to post-mitotic cyst cells, providing a tractable model to study the links between stem cell identity and proliferation. We show that, while cell-cycle progression is required for CySC self-renewal, the E2f1/Dp transcription factor is dispensable for self-renewal but instead must be silenced by the Drosophila retinoblastoma homolog, Rbf, to permit differentiation. Continued E2f1/Dp activity inhibits the expression of genes important for mitochondrial activity. Furthermore, promoting mitochondrial biogenesis rescues the differentiation of CySCs with ectopic E2f1/Dp activity but not their cell-cycle exit. In sum, E2f1/Dp coordinates cell-cycle progression with stem cell identity by regulating the metabolic state of CySCs

Inhibition of PKCε induces primordial germ cell reprogramming into pluripotency by HIF1&2 upregulation and histone acetylation

Historically, primordial germ cells (PGCs) have been a good model to study pluripotency. Despite their low numbers and limited accessibility in the mouse embryo, they can be easily and rapidly reprogrammed at high efficiency with external physicochemical factors and do not require transcription factor transfection. Employing this model to deepen our understanding of cell reprogramming, we specifically aimed to determine the relevance of Ca2+ signal transduction pathway components in the reprogramming process. Our results showed that PGC reprogramming requires a normal extracellular [Ca2+] range, in contrast to neoplastic or transformed cells, which can continue to proliferate in Ca2+-deficient media, differentiating normal reprogramming from neoplastic transformation. Our results also showed that a spike in extracellular [Ca2+] of 1-3 mM can directly reprogram PGC. Intracellular manipulation of Ca2+ signal transduction pathway components revealed that inhibition of classical Ca2+ and diacylglycerol (DAG)-dependent PKCs, or intriguingly, of only the novel DAG-dependent PKC, PKCε, were able to induce reprogramming. PKCε inhibition changed the metabolism of PGCs toward glycolysis, increasing the proportion of inactive mitochondria. This metabolic switch from oxidative phosphorylation to glycolysis is mediated by hypoxia-inducible factors (HIFs), given we found upregulation of both HIF1α and HIF2α in the first 48 hours of culturing. PKCε inhibition did not change the classical pluripotency gene expression of PGCs, Oct4, or Nanog. PKCε inhibition changed the histone acetylation of PGCs, with histones H2B, H3, and H4 becoming acetylated in PKCε-inhibited cultures (markers were H2BacK20, H3acK9, and H4acK5K8, K12, K16), suggesting that reprogramming by PKCε inhibition is mediated by histone acetylation

Diagnóstico Territorial del Litoral de Cantabria. Volumen I: Informe.

Estudios de base para la redacción del Plan de Ordenación del Litoral (POL) de Cantabria.Este proyecto de investigación aplicada se ha realizado gracias al Convenio de Colaboración entre el Gobierno de Cantabria y la Universidad de Cantabria titulado “Diagnóstico Territorial del Litoral de Cantabria”

Análisis Socio-Urbanístico de Cantabria. Volumen II: Análisis del Planeamiento.

Estudios de base para la redacción de las Normas Urbanísticas Regionales (NUR) de Cantabria.Este proyecto de investigación aplicada se ha realizado gracias al Convenio de Colaboración entre el Gobierno de Cantabria y la Universidad de Cantabria titulado “Análisis Socio-Urbanístico de Cantabria”