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Floral induction in Tulipa gesneriana and Lilium longiflorum is triggered by contrasting temperature conditions, high and low temperature, respectively. In Arabidopsis, the floral integrator FLOWERING LOCUS T (FT), a member of the PEBP (phosphatidyl ethanolamine-binding protein) gene family, is a key player in flowering time control. In this study, one PEBP gene was identified and characterized in lily (LlFT) and three PEBP genes were isolated from tulip (TgFT1, TgFT2 and TgFT3). Overexpression of these genes in Arabidopsis thaliana resulted in an early flowering phenotype for LlFT and TgFT2, but a late flowering phenotype for TgFT1 and TgFT3. Overexpression of LlFT in L. longiflorum also resulted in an early flowering phenotype, confirming its proposed role as a flowering time-controlling gene. The tulip PEBP genes TgFT2 and TgFT3 have a similar expression pattern in tulip, but show opposite effects on the timing of flowering in Arabidopsis. Therefore, the difference between these two proteins was further investigated by interchanging amino acids thought to be important for the FT function. This resulted in the conversion of phenotypes in Arabidopsis upon overexpressing the substituted TgFT2 and TgFT3 genes, revealing the importance of these interchanged amino acid residues. Based on all obtained results, we hypothesize that LlFT is involved in creating meristem competence to flowering-related cues in lily, and TgFT2 is considered to act as a florigen involved in the floral induction in tulip. The function of TgFT3 remains unclear, but, based on our observations and phylogenetic analysis, we propose a bulb-specific function for this gene.

Tesis doctoral, 265 p., tablas e imágenes., [EN] Our research focuses on understanding the molecular mechanisms that mediate the actions of glucocorticoids (GCs) in skin pathophysiology through functional analysis of the GC receptor (GR) and the mineralocorticoid receptor (MR), two highly related structural and functionally proteins, which act as ligand-dependent transcription factors. Our previous data show that GR plays a central role in skin development; in adulthood, both GR and MR act as anti-inflammatory mediators in skin diseases (Sevilla et al. 2013; Boix et al. 2016). However, we did not know if the receptors exerted cooperative or antagonistic functions in the epidermis. This doctoral thesis has focused on the generation and characterization of mice with specific inactivation in the epidermis of GR and MR (double knock-out or DKO mice). At birth, DKO show a skin phenotype with defective epidermal differentiation and a unique inflammatory state characterized by epithelial immune infiltrates and alterations in gene expression, similar to psoriatic lesions. This phenotype was much more severe than that of individual KO (GR epidermal KO or GREKO and MR epidermal KO or MREKO mice), but resolved spontaneously from postnatal day 3. In adulthood, DKO skin showed an increase in epidermal thickness, similar to that of individual KO. All KO mice showed greater susceptibility to acute inflammation compared to controls (CO), which was not effectively counteracted by topical treatment with GCs. Furthermore, DKO mice show a greater susceptibility to imiquimod-induced psoriasis relative to individual KO. The increased inflammatory response in DKO was consistent with a significant increase in AP-1 and NF-kappaB activity in DKO keratinocytes relative to CO or individual KO. Taken together, our data show that epidermal GR and MR act cooperatively to counteract skin inflammation, during development and adulthood, and that both are required for optimal transcriptional response and therapeutic activity of GCs. Prolonged treatments with pharmacological doses of GCs produce defects such as cutaneous atrophy, similar to that which occurs during chronological aging, which correlates with an increase in endogenous local levels of GCs. This work has addressed the phenotypic consequences of epidermal loss of MR during chronological aging and the mechanisms involved. The 13-month-old MREKO mice were resistant to epidermal atrophy but displayed reduced dermal thickness and collagen deposition, in part due to a decrease in SMAD2 3 activity relative to the skin of CO mice. In addition, the subcutaneous adipose tissue (dWAT) thickened 2.5 times in MREKO vs CO at 13 months, with hyperplasia and hypertrophy of adipocytes. These changes were triggered, at least in part, through alterations in GC-mediated signaling, and the activation of WNT/beta-catenin induced by epidermal paracrine signals that led to increased expression of Pparg. These results show a crucial role for epidermal MR in the regulation of the cross-talk between compartments during chronological skin aging., [ES] Nuestra investigación se centra en comprender los mecanismos moleculares que median las acciones de los glucocorticoides (GCs) en la fisiopatología de la piel mediante el análisis funcional del receptor de GCs (GR) y el receptor de mineralocorticoides (MR), dos proteínas altamente relacionadas estructural y funcionalmente, que actúan como factores de transcripción dependientes de ligando. Nuestros datos previos demuestran que GR juega un papel central en el desarrollo de la piel; en la edad adulta, tanto GR como MR actúan como mediadores anti-inflamatorios en enfermedades cutáneas (Sevilla et al. 2013; Boix et al. 2016). No obstante, desconocíamos si los receptores ejercían funciones cooperativas o antagónicas en la epidermis. Esta tesis doctoral se ha centrado en la generación y caracterización de ratones con inactivación específica en la epidermis de GR y MR (ratones double knock-out o DKO). Al nacer, los DKO mostraron un fenotipo cutáneo con diferenciación epidérmica defectuosa y un estado inflamatorio único caracterizado por infiltrados inmunes epiteliales y alteraciones en la expresión génica, similar a las lesiones psoriáticas. Este fenotipo fue mucho más severo que el de los KO individuales (ratones GR epidermal KO o GREKO y MR epidermal KO o MREKO), pero se resolvió espontáneamente a partir del día post-natal 3. En la edad adulta, la piel DKO mostró un aumento en el grosor epidérmico, similar al de los KO individuales. Todos los ratones KO mostraron una mayor susceptibilidad a la inflamación aguda respecto a los controles (CO), que no se contrarrestó de forma efectiva por un tratamiento tópico con GCs. Además, los ratones DKO mostraron una mayor susceptibilidad a la psoriasis inducida por imiquimod respecto a los KO individuales. El aumento de la respuesta inflamatoria en los DKO era consistente con un aumento significativo de la actividad de AP-1 y NF-kappaB en queratinocitos DKO respecto a los CO o KO individuales. En conjunto, nuestros datos demuestran que GR y MR epidérmicos actúan de manera cooperativa para contrarrestar la inflamación de la piel, durante el desarrollo y la edad adulta, y que ambos son necesarios para una respuesta transcripcional óptima y una actividad terapéutica de los GCs. Los tratamientos prolongados con dosis farmacológicas de GCs producen defectos como la atrofia cutánea, similar a la que tiene lugar durante el envejecimiento cronológico, que correlaciona con un aumento de los niveles locales endógenos de GCs. Este trabajo ha abordado las consecuencias fenotípicas de la pérdida epidérmica de MR durante el envejecimiento cronológico y los mecanismos involucrados. Los ratones MREKO de 13 meses de edad fueron resistentes a la atrofia epidérmica pero mostraron un menor grosor dérmico y depósito de colágeno, en parte debido a una disminución de la actividad SMAD2/3 respecto a la piel de ratones CO. Además, el tejido adiposo subcutáneo (dWAT) se engrosó 2.5 veces en MREKO vs CO a los 13 meses, con hiperplasia e hipertrofia de adipocitos. Estos cambios se desencadenaron, al menos en parte, a través de alteraciones en la señalización mediada por GCs, y la activación de WNT/beta-catenina inducida por señales paracrinas epidérmicas que condujeron al aumento de expresión de Pparg. Estos resultados demuestran un papel crucial de MR epidérmico en la regulación del cross-talk entre compartimientos durante el envejecimiento cronológico de la piel., SAF2014-59474-R SAF2017-88046-R Judit Bigas Corominas ha disfrutado de una beca predoctoral FPI (BES2015-072722) otorgada por el Ministerio de Economía y Competitividad, asociada al proyecto SAF2014-59474-R. Agradecemos el apoyo de COST ADMIRE BM-1301 y NuRCaMeIn (SAF2015-71878-REDT y SAF2017-90604-REDT).

11 págs., 6 figuras. All data generated or analyzed during this study are included in this published article (and its SupplementaryInformation fles) at https://doi.org/10.1038/s41598-020-75853-5., Glucocorticoid (GC) actions are mediated through two closely related ligand-dependent transcription factors, the GC receptor (GR) and the mineralocorticoid receptor (MR). Given the wide and effective use of GCs to combat skin inflammatory diseases, it is important to understand the relative contribution of these receptors to the transcriptional response to topical GCs. We evaluated the gene expression profiles in the skin of mice with epidermal-specific loss of GR (GREKO), MR (MREKO), or both (double KO; DKO) in response to dexamethasone (Dex). The overall transcriptional response was abolished in GREKO and DKO skin suggesting dependence of the underlying dermis on the presence of epidermal GR. Indeed, the observed dermal GC resistance correlated with a constitutive decrease in GR activity and up-regulation of p38 activity in this skin compartment. Upon Dex treatment, more than 90% of differentially expressed genes (DEGs) in CO overlapped with MREKO. However, the number of DEGs was fourfold increased and the magnitude of response was higher in MREKO vs CO, affecting both gene induction and repression. Taken together our data reveal that, in the cutaneous transcriptional response to GCs mediated through endogenous receptors, epidermal GR is mandatory while epidermal MR acts as a chief modulator of gene expression., Tis work was supported by grant SAF2017-88046-R (MICINN, Spanish Government). J. Bigas is recipient of FPI fellowship of MINECO. We thank NURCAMEIN (SAF2017-90604-REDT) for support for dissemination.We also thank Julia Boix for assisting with the animal experiments.

10 páginas, 5 figuras. Supplementary material is linked to the online version of the paper at https://doi.org/10.1016/j.jid.2020.03.933, The increased production of endogenous glucocorticoids (GCs) in the skin of the elderly population contributes to age-related defects strikingly similar to those occurring after pharmacologic treatments with GCs. GCs act through the ligand-dependent transcription factors GC receptor (GR) and mineralocorticoid receptor (MR). We reported that epidermal MR plays nonredundant roles relative to GR in adult mouse skin homeostasis; however, its relative contribution to natural skin aging has not been previously investigated. A 13-month-old MR epidermal knockout (MREKO) mice showed differential features of aging relative to controls (CO) in all skin compartments. MREKO mice were resistant to age-induced epidermal atrophy but showed reduced dermal thickness, with decreased collagen deposition and decreased SMAD2 and 3 activity. Importantly, the dermal white adipose tissue (dWAT) was 2.5-fold enlarged in 13-month MREKO versus CO, featuring adipocyte hyperplasia and hypertrophy at least in part through early increases in Pparg. These changes correlated with compartment-specific alterations in GC signaling. In addition, conditioned medium from MREKO keratinocytes increased adipocyte differentiation, indicating paracrine regulation of adipogenesis through mechanisms that include activation of β-catenin signaling. These findings highlight the importance of epidermal MR in regulating cross-talk among skin compartments in naturally aged skin through GC and β-catenin signaling pathways., This research was supported by grant SAF2017-880464-R (Ministerio de Economı´a y Competitividad [MINECO], Spanish Government). JB is a recipient of Formacio´n Personal Investigador fellowship from MINECO (BES2015- 072722). The authors thank MINECO Nuclear Receptors in Cancer, Metabolism, and Inflammation for Networks of Excellence grant (SAF2017-90604-REDT).

14 páginas, 6 figuras. Material suplementario en https://doi.org/10.1038/s41419-018-0673-z., Endogenous and synthetic glucocorticoids (GCs) regulate epidermal development and combat skin inflammatory diseases. GC actions can be mediated through the GC receptor (GR) and/or the mineralocorticoid receptor (MR), highly homologous ligand-activated transcription factors. While the role of GR as a potent anti-inflammatory mediator is well known, that of MR is not as clear, nor is whether these receptors cooperate or antagonize each other in the epidermis. To address this, we generated mice with epidermal-specific loss of both receptors (double knockout, DKO), and analyzed the phenotypical and functional consequences relative to single KOs or controls (CO). At birth, DKO epidermis displayed a phenotype of defective differentiation and inflammation, which was more severe than in either single KO, featuring neutrophil-containing infiltrates, and gene dysregulation characteristic of human psoriatic lesions. This phenotype resolved spontaneously. However, in adulthood, single or combined loss of GC receptors increased susceptibility to inflammation and hyperproliferation triggered by phorbol ester which, different to CO, was not effectively counteracted by GC treatment. Also, DKOs were more susceptible to imiquimod-induced psoriasis than CO showing severe defective epidermal differentiation and microabcesses while single KOs showed an intermediate response. Immortalized DKO keratinocytes featured increased proliferation kinetics and reduced cell size, a unique phenotype relative to single KO cells. The lack of GR and MR in keratinocytes, individual or combined, caused constitutive increases in p38 and ERK activities, which were partially reversed upon reinsertion of receptors into DKO cells. DKO keratinocytes also displayed significant increases in AP-1 and NF-κB transcriptional activities, which were partially rescued by ERK and p38 inhibition, respectively. Reinsertion of GR and MR in DKO keratinocytes resulted in physical and cooperative functional interactions that restored the transcriptional response to GCs. In conclusion, our data have revealed that epidermal GR and MR act cooperatively to regulate epidermal development and counteract skin inflammation., This work was supported by grants SAF2014-59474-R and SAF2017-88046-R (MINECO, Spanish Government). J.B. is recipient of FPI fellowship from MINECO (BES2015-072722). We thank COST ADMIRE BM-1301 and NURCAMEIN (SAF2015-71878-REDT and SAF2017-90604-REDT) for support for dissemination.

10 páginas, 4 figuras, 1 tabla., Primary aldosteronism (PA) is a disease characterized by high aldosterone levels caused by benign adrenal tumors being the most frequent cause of secondary hypertension. Aldosterone plays vital physiological roles through the mineralocorticoid receptor (MR) but in certain cell types, it can also activate the glucocorticoid (GC) receptor (GR). Both MR and GR are structurally and functionally related and belong to the same family of ligand-dependent transcription factors that recognize identical GC regulatory elements (GREs) on their target genes. GCs play key roles in skin pathophysiology acting through both GR and MR; however, the effects of aldosterone and the potential association of PA and skin disease were not previously addressed. Skin samples from PA revealed histopathological alterations relative to control subjects, featuring epidermal hyperplasia, impaired differentiation, and increased dermal infiltrates, correlating with increased NF-κB signaling and up-regulation of TNF-A and IL-6 cytokines. PA skin samples also showed significantly higher expression of MR, GR, and HSD11B2. In cultured keratinocytes, aldosterone treatment increased GRE transcriptional activity which was significantly inhibited by co-treatment with GR- and MR-antagonists. This study demonstrates that high levels of aldosterone in PA patients correlate with skin anomalies and inflammatory features associated with abnormal GR/MR activation in epidermal keratinocytes., This work was supported by grant SAF2014-59474-R (MINECO, Spanish Government). J. Boix and J. Bigas are recipients of FPI fellowships of MINECO. We thank COST ADMIRE BM-1301 and NURCAMEIN (SAF2015-71878-REDT) for support for dissemination. We thank Jose Nieto for assistance with histopathological work. We are indebted to the patients and healthcare professionals that collaborated in this study.

Matrix metalloproteinases (MMPs, including the membrane-type MMPs (MT-MMPs)), a disintegrin and metalloproteinase (ADAM), and ADAM with thrombospondin motifs belong to the metzincins, a subclass of metalloproteinases that contain a Met residue and a Zn(2+) ion at the catalytic site necessary for enzymatic reaction. MMP proteolytic activity is mainly controlled by their natural tissue inhibitors of metalloproteinase (TIMP). A number of synthetic inhibitors have been developed to control deleterious MMP activity. The roles of MMPs and some of their ECM substrates in CNS physiology and pathology are covered by other chapters of the present volume and will thus not be addressed in depth. This chapter will focus (i) on the endogenous MMP inhibitors in the CNS, (ii) on MMP and TIMP regulations in three large classes of neuropathologic processes (inflammatory, neurodegenerative, and infectious), and (iii) on synthetic inhibitors of MMPs and the perspective of their use in different brain diseases.