Remodeling arteries: studying the mechanical properties of 3D-bioprinted hybrid photoresponsive materials.

3D-printed cell models are currently in the spotlight of medical research. Whilst significant advances have been made, there are still aspects that require attention to achieve more realistic models which faithfully represent the in vivo environment. In this work we describe the production of an artery model with cyclic expansive properties, capable of mimicking the different physical forces and stress factors that cells experience in physiological conditions. The artery wall components are reproduced using 3D printing of thermoresponsive polymers with inorganic nanoparticles (NPs) representing the outer tunica adventitia, smooth muscle cells embedded in extracellular matrix representing the tunica media, and finally a monolayer of endothelial cells as the tunica intima. Cyclic expansion can be induced thanks to the inclusion of photo-responsive plasmonic NPs embedded within the thermoresponsive ink composition, resulting in changes in the thermoresponsive polymer hydration state and hence volume, in a stimulated on-off manner. By changing the thermoresponsive polymer composition, the transition temperature and pulsatility can be efficiently tuned. We show the direct effect of cyclic expansion and contraction on the overlying cell layers by analyzing transcriptional changes in mechanoresponsive mesenchymal genes associated with such microenvironmental physical cues. The technique described herein involving stimuli-responsive 3D printed tissue constructs, also described as four- dimensional (4D) printing, offers a novel approach for the production of dynamic biomodels.Financial support is acknowledged from the MCIN/AEI/ 10.13039/501100011033 through grant # PID2019-108854RAI00. C. G. A. thanks to the Ministerio de Ciencia e Innovacio´n (MCIN) for a Juan de la Cierva Incorporacio´n Fellowship (IJC2019-040827-I). M. S.-A. is recipient of a Ramo´n y Cajal contract and a ‘‘Generacio´n de Conocimiento’’ grant from the Ministerio de Ciencia e Innovacio´n (RYC2020-029690-I and PID2021-128106NA-I00). MAdP is coordinator and PL of ‘‘AtheroConvergence’’ La Caixa Foundation Health Research consortium (HR20-00075). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the MCIN and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (grant CEX2020-001041-S). We acknowledge ALBA for provision of synchrotron radiation facilities. We would like to thank Dr Marc Malfois for assistance in using BL11-NCD beamline, and Unai Cossı´o and Daniel Padro for help with image analysis.S

Procesos geomorfológicos activos en cárcavas del borde del piedemonte norte de la Sierra de Guadarrama (Provincia de Segovia, España)

Dos localizaciones situadas cerca del borde del piedemonte norte de la Sierra de Guadarrama (provincia de Segovia) ofrecen formas erosivas en cárcavas bien desarrolladas: (a) un conjunto de barrancos encajados sobre arenas arcósicas del Mioceno, en un relieve de lomas y vaguadas del suroeste provincial; (b) cárcavas sobre arenas silíceas del Cretácico Superior, en un relieve de laderas de mesas y cuestas de la zona centro sur de la Provincia. En este trabajo se caracteriza la actividad geomorfológica de esos barrancos y cárcavas, y se inicia su cuantificación. El objetivo está encaminado a conocer qué procesos movilizan sedimentos, y a evaluar sus tasas de actuación, intensidad, frecuencia de ocurrencia y conectividad entre los mismos. Los procesos de erosión hídrica por salpicadura, arroyada laminar y concentrada en rills, junto con la actividad gravitacional observada, movilizan materiales desde las cabeceras de las cárcavas hasta los colectores, rellenándolos; éstos son evacuados mediante procesos de encajamiento en los canales efímeros, y sedimentados en pequeños conos aluviales. En los barrancos sobre arcosas, los eventos de precipitación poco intensos y de alta frecuencia tienden a rellenar los lechos arenosos, mientras que la fusión nival y las precipitaciones de alta intensidad y baja frecuencia vacían los canales, sedimentando en zonas apicales de los conos aluviales. En las cárcavas sobre arenas silíceas, los primeros datos obtenidos apuntan a unas tasas de erosión y producción de sedimentos muy elevadas, ya que sobre ellas se produce escorrentía y erosión hídrica de manera casi instantánea; por ello, los eventos de precipitación de baja intensidad son capaces de sedimentar en las zonas apicales de los conos, mientras que los eventos de alta intensidad originan lóbulos telescópicos sobre conos aluviales existentes en pedimentos. [ABSTRACT] Two areas located at the edge of the North piedmont of the Guadarrama Mountains (province of Segovia) show a conspicuous development of gullies. A series of valley side gullies, or ravines, cut on arkosic sand sediments of Miocene age at the Río Chico Valley (southwest of the Segovia province); and slope gullies, cut on silica sand, shale and gravel sediments of Upper Cretaceous age, on the slopes of a set of mesas and cuestas at the río Cega piedmont (Pedraza region, south centre of the Segovia province). This paper characterizes the geomorphic activity of both types of gullies. In addition, the quantification of their current activity is initiated. The objectives are: to know which processes are eroding and mobilizing the sediments within the gullies, and to evaluate their rates, intensity, frequency and connectivity. A detailed field survey shows that weathering processes (sandstone sheeting, and the formation of popcorn structures on shale layers), and splash, sheet and rill erosion, along with sand and mud falls, slides and flows move sediment from the gully slopes and internal divides to the dry washes. These materials are temporary stored in ephemeral stream channels (filled with sandy bed material), evacuated by stream-bed scour and fill processes, and deposited in alluvial cones. In order to get a first approximation of the amount of erosion and sediment movement, a set of field methods have been applied to these areas. These methods include: erosion pins, measurement of pedestals, system of rods and washers, pit traps (box and gabion check-dam types), and topographic surveys after extensive sedimentation on alluvial cones, along with the installation of pluviographs. The results show how on the arkosic valley side gullies, the precipitation events of low intensity and high frequency tend to fill the sandy stream-beds, whereas the snowmelt and the high intensity and low frequency precipitation events scour the sandy stream-beds. The sedimentation occurs here at the apex part of the alluvial cones, which rest directly on the nearby floodplain of the Chico River. On the silica sand slope gullies, the first gathered data point at very high rates of erosion and sedimentation (44.1 tons/ha for a single event), which is interpreted due to the fact that runoff and water erosion occurs here almost instantaneously after precipitation. Here, the precipitation events of low intensity and high frequency produce sedimentation at the apex part of the alluvial cones, whereas the high intensity and low frequency precipitation events sediment in the form of telescopic lobes, on existing alluvial cones, which rest on pediments

Caveolin-1 is required for TGF-β-induced transactivation of the EGF receptor pathway in hepatocytes through the activation of the metalloprotease TACE/ADAM17

Transforming growth factor-beta (TGF-β) plays a dual role in hepatocytes, inducing both pro- and anti-apoptotic responses, whose balance decides cell fate. Survival signals are mediated by the epidermal growth factor receptor (EGFR) pathway, which is activated by TGF-β in these cells. Caveolin-1 (Cav1) is a structural protein of caveolae linked to TGF-β receptors trafficking and signaling. Previous results have indicated that in hepatocytes, Cav1 is required for TGF-β-induced anti-apoptotic signals, but the molecular mechanism is not fully understood yet. In this work, we show that immortalized Cav1(-/-) hepatocytes were more sensitive to the pro-apoptotic effects induced by TGF-β, showing a higher activation of caspase-3, higher decrease in cell viability and prolonged increase through time of intracellular reactive oxygen species (ROS). These results were coincident with attenuation of TGF-β-induced survival signals in Cav1(-/-) hepatocytes, such as AKT and ERK1/2 phosphorylation and NFκ-B activation. Transactivation of the EGFR pathway by TGF-β was impaired in Cav1(-/-) hepatocytes, which correlated with lack of activation of TACE/ADAM17, the metalloprotease responsible for the shedding of EGFR ligands. Reconstitution of Cav1 in Cav1(-/-) hepatocytes rescued wild-type phenotype features, both in terms of EGFR transactivation and TACE/ADAM17 activation. TACE/ADAM17 was localized in detergent-resistant membrane (DRM) fractions in Cav1(+/+) cells, which was not the case in Cav1(-/-) cells. Disorganization of lipid rafts after treatment with cholesterol-binding agents caused loss of TACE/ADAM17 activation after TGF-β treatment. In conclusion, in hepatocytes, Cav1 is required for TGF-β-mediated activation of the metalloprotease TACE/ADAM17 that is responsible for shedding of EGFR ligands and activation of the EGFR pathway, which counteracts the TGF-β pro-apoptotic effects. Therefore, Cav1 contributes to the pro-tumorigenic effects of TGF-β in liver cancer cells.This work was supported by grants from: (1) the Ministry of Economy and Competitiveness (MINECO), Spain (BFU2012-35538 and ISCIII-RTICC: RD12-0036-0029 to IF; SAF2013-43713 to PM-S; BFU2012-33932 to GE; SAF2011-25047 and CSD2009-00016 to MAdP); (2) AGAUR-Generalitat de Catalunya (2009SGR-312 to IF); and (3) People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no. PITN-GA-2012-316549 (IT LIVER) to IF JM-C and RM-V were recipients of pre-doctoral fellowships from the FPU program (Ministry of Education, Culture and Sport, Spain) and the FPI program (associated to SAF201125047, MINECO, Spain), respectively. We acknowledge the review and suggestions of Dr. Christoph Meyer (University of Heidelberg, Mannheim, Germany).S

Functional connectivity in mild cognitive impairment during a memory task: implications for the disconnection hypothesis.

Mild cognitive impairment (MCI) has been considered an intermediate state between healthy aging and dementia. The early damage in anatomical connectivity and progressive loss of synapses that characterize early Alzheimer's disease suggest that MCI could also be a disconnection syndrome. Here, we compare the degree of synchronization of brain signals recorded with magnetoencephalography from patients (22) with MCI with that of healthy controls (19) during a memory task. Synchronization Likelihood, an index based on the theory of nonlinear dynamical systems, was used to measure functional connectivity. During the memory task patients showed higher interhemispheric synchronization than healthy controls between left and right -anterior temporo-frontal regions (in all studied frequency bands) and in posterior regions in the γ band. On the other hand, the connectivity pattern from healthy controls indicated two clusters of higher synchronization, one among left temporal sensors and another one among central channels. Both of them were found in all frequency bands. In the γ band, controls showed higher Synchronization Likelihood values than MCI patients between central-posterior and frontal-posterior channels and a high synchronization in posterior regions. The inter-hemispheric increased synchronization values could reflect a compensatory mechanism for the lack of efficiency of the memory networks in MCI patients. Therefore, these connectivity profiles support only partially the idea of MCI as a disconnection syndrome, as patients showed increased long distance inter-hemispheric connections but a decrease in antero-posterior functional connectivit

The Dioxin receptor modulates Caveolin-1 mobilization during directional migration: role of cholesterol

Background: Adhesion and migration are relevant physiological functions that must be regulated by the cell under both normal and pathological conditions. The dioxin receptor (AhR) has emerged as a transcription factor regulating both processes in mesenchymal, epithelial and endothelial cells. Indirect results suggest that AhR could cooperate not only with additional transcription factors but also with membrane-associated proteins to drive such processes. Results: In this study, we have used immortalized and primary dermal fibroblasts from wild type (AhR+/+) and AhR-null (AhR-/-) mice to show that AhR modulates membrane distribution and mobilization of caveolin-1 (Cav-1) during directional cell migration. AhR co-immunoprecipitated with Cav-1 and a fraction of both proteins co-localized to detergent-resistant membrane microdomains (DRM). Consistent with a role of AhR in the process, AhR-/-cells had a significant reduction in Cav-1 in DRMs. Moreover, high cell density reduced AhR nuclear levels and moved Cav-1 from DRMs to the soluble membrane in AhR+/+ but not in AhR-/-cells. Tyrosine-14 phosphorylation had a complex role in the mechanism since its upregulation reduced Cav-1 in DRMs in both AhR+/+ and AhR-/-cells, despite the lower basal levels of Y-14-Cav-1 in the null cells. Fluorescence recovery after photobleaching revealed that AhR knock-down blocked Cav-1 transport to the plasma membrane, a deficit possibly influencing its depleted levels in DRMs. Membrane distribution of Cav-1 in AhR-null fibroblasts correlated with higher levels of cholesterol and with disrupted membrane microdomains, whereas addition of exogenous cholesterol changed the Cav-1 distribution of AhR+/+ cells to the null phenotype. Consistently, higher cholesterol levels enhanced caveolae-dependent endocytosis in AhR-null cells. Conclusions: These results suggest that AhR modulates Cav-1 distribution in migrating cells through the control of cholesterol-enriched membrane microdomains. Our study also supports the likely possibility of membrane-related, transcription factor independent, functions of AhR.This work was supported by grants to P. M. F-S. from the Spanish Ministry of Science and Innovation (SAF2008-00462 and BFU2011-22678) and from the Junta de Extremadura (GR10008). Research at P. M. F-S laboratory is also funded by the Red Tematica de Investigacion Cooperativa en Cancer (RTICC), Fondo de Investigaciones Sanitarias (FIS), Carlos III Institute, Spanish Ministry of Health (RD12/0036/0032). J.R.B. was a F.P.U. program fellow from the Spanish Ministry of Education and Sciences. All Spanish funding is co-sponsored by the European Union FEDER program. The support and help of the Servicio de Tecnicas Aplicadas a las Biociencia (STAB) of the Universidad de Extremadura is greatly acknowledged. We are very grateful to Dr. Lisardo Bosca (Instituto de Investigaciones Biomedicas, Madrid, Spain) for providing the Cav-1-GFP and the Cav-1Y14F-GFP expression vectors and to Dr. Miguel A. Alonso Lebrero (Centro de Biologia Molecular Severo Ochoa, Madrid, Spain) for assistance with the sucrose density gradient method. The technical support of Eva Barrasa is greatly appreciated.S