Facilitating trypanosome imaging.

Research on trypanosomes as a model organism has provided a substantial contribution to a detailed understanding of basic cellular processes within the last few years. At the same time, major advances in super-resolution microscopy have been achieved, facilitating the resolution of biological structures in living cells at a scale of a few nm. However, the motility of trypanosomes has prevented access to high resolution microscopy of live cells. Here, we present a hydrogel based on poly(ethylene glycol) functionalized with either norbornene or thiol moieties for UV induced thiol-ene crosslinking for the embedding and imaging of live trypanosomes. The resulting gel exhibits low autofluorescence properties, immobilizes the cells efficiently on the nanometer scale and is compatible with cell viability for up to one hour at 24 °C. We applied super-resolution imaging to the inner plasma membrane leaflet using lipid-anchored eYFP as a probe. We find specific domains within the membrane where the fluorescence either accumulates or appears diluted rather than being homogenously distributed. Based on a Ripley's analysis, the size of the domains was determined to be raccumulated=170±5 nm and rdilute>115±15 nm. We hypothesize that this structuring of the membrane is associated with the underlying cytoskeleton.ME is supported by DFG grants EN305 and SPP1726. ME is a member of the Wilhelm Conrad Röntgen Center for Complex Material Systems (RCCM). Work in MC's lab was funded by the a Wellcome Trust award (093008/Z10/Z)

Shielding of actin by the endoplasmic reticulum impacts nuclear positioning

© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.Nuclear position is central to cell polarization, and its disruption is associated with various pathologies. The nucleus is moved away from the leading edge of migrating cells through its connection to moving dorsal actin cables, and the absence of connections to immobile ventral stress fibers. It is unclear how these asymmetric nucleo-cytoskeleton connections are established. Here, using an in vitro wound assay, we find that remodeling of endoplasmic reticulum (ER) impacts nuclear positioning through the formation of a barrier that shields immobile ventral stress fibers. The remodeling of ER and perinuclear ER accumulation is mediated by the ER shaping protein Climp-63. Furthermore, ectopic recruitment of the ER to stress fibers restores nuclear positioning in the absence of Climp-63. Our findings suggest that the ER mediates asymmetric nucleo-cytoskeleton connections to position the nucleus.This work was supported by the European Research Council H2020-GA 810207-ARPCOMPLEXITY and FP7-GA 617676 PHONICS (ERG), EMBO installation (ERG), Marine Biological Laboratory Whitman Center Fellowship (ERG), Association pour la Recherche sur le Cancer and La Ligue Nacionale contre le Cancer (ERG) and Fundação para a Ciência e a Tecnologia (SFRH/BD/112286/2015)(CJ), European Research Council H2020-GA 679368 AXIAL.EC (CF); Fundação para a Ciência e Tecnologia (PTDC/MED-PAT/31639/2017; CEECIND/04251/2017)(CF) and Fondation LeDucq (17CVD03)(CF).info:eu-repo/semantics/publishedVersio

PolNet:A Tool to Quantify Network-Level Cell Polarity and Blood Flow in Vascular Remodeling

In this article, we present PolNet, an open-source software tool for the study of blood flow and cell-level biological activity during vessel morphogenesis. We provide an image acquisition, segmentation, and analysis protocol to quantify endothelial cell polarity in entire in vivo vascular networks. In combination, we use computational fluid dynamics to characterize the hemodynamics of the vascular networks under study. The tool enables, to our knowledge for the first time, a network-level analysis of polarity and flow for individual endothelial cells. To date, PolNet has proven invaluable for the study of endothelial cell polarization and migration during vascular patterning, as demonstrated by two recent publications. Additionally, the tool can be easily extended to correlate blood flow with other experimental observations at the cellular/molecular level. We release the source code of our tool under the Lesser General Public License

Non-canonical Wnt signaling regulates junctional mechanocoupling during angiogenic collective cell migration

© 2019, Carvalho et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.Morphogenesis of hierarchical vascular networks depends on the integration of multiple biomechanical signals by endothelial cells, the cells lining the interior of blood vessels. Expansion of vascular networks arises through sprouting angiogenesis, a process involving extensive cell rearrangements and collective cell migration. Yet, the mechanisms controlling angiogenic collective behavior remain poorly understood. Here, we show this collective cell behavior is regulated by non-canonical Wnt signaling. We identify that Wnt5a specifically activates Cdc42 at cell junctions downstream of ROR2 to reinforce coupling between adherens junctions and the actin cytoskeleton. We show that Wnt5a signaling stabilizes vinculin binding to alpha-catenin, and abrogation of vinculin in vivo and in vitro leads to uncoordinated polarity and deficient sprouting angiogenesis in Mus musculus. Our findings highlight how non-canonical Wnt signaling coordinates collective cell behavior during vascular morphogenesis by fine-tuning junctional mechanocoupling between endothelial cells.Research was supported by European Research Council starting grant (679368), the H2020-Twinning grant (692322), the Fundação para a Ciência e a Tecnologia funding (grants: IF/00412/2012; EXPL-BEX-BCM-2258–2013; PRECISE-LISBOA-01–0145-FEDER-016394; UID/BIM/50005/2019, a project funded by Fundação para a Ciência e a Tecnologia (FCT)/ Ministério da Ciência,Tecnologia e Ensino Superior (MCTES) through Fundos do Orçamento de Estado; and a grant from the Fondation Leducq (17CVD03); and personal fellowships: BD/52224/2013​​ to JRC, BD/105856/2014 to PB, and BD/128375/2017 to CF) and LISBOA-01–0145-FEDER-007391, project cofunded by FEDER, through POR Lisboa 2020 - Programa Operacional Regional de Lisboa, PORTUGAL 2020, and Fundação para a Ciência e a Tecnologia.info:eu-repo/semantics/publishedVersio

Competition for endothelial cell polarity drives vascular morphogenesis in the mouse retina

© 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Blood-vessel formation generates unique vascular patterns in each individual. The principles governing the apparent stochasticity of this process remain to be elucidated. Using mathematical methods, we find that the transition between two fundamental vascular morphogenetic programs-sprouting angiogenesis and vascular remodeling-is established by a shift of collective front-to-rear polarity of endothelial cells in the mouse retina. We demonstrate that the competition between biochemical (VEGFA) and mechanical (blood-flow-induced shear stress) cues controls this collective polarity shift. Shear stress increases tension at focal adhesions overriding VEGFA-driven collective polarization, which relies on tension at adherens junctions. We propose that vascular morphogenetic cues compete to regulate individual cell polarity and migration through tension shifts that translates into tissue-level emergent behaviors, ultimately leading to uniquely organized vascular patterns.Funding: European Research Council: C.A.F. (679368); X.T. (883739). European Commission: C.A.F. and M.O.B. (801423); X.T. and P.R.-C. (731957). H2020-MSCA-PF grants to M.G.-G. (797621) and M.O. (842498). Fondation LeDucq: C.A.F., A.E., and M.O.B. (17CVD03). EPSRC: M.O.B. (EP/T008806/1; EP/R029598/1). Fundação para a Ciência e Tecnologia: C.A.F. (PTDC/MED-PAT/31639/2017; PTDC/BIA-CEL/32180/2017; CEECIND/04251/2017). Spanish Ministry of Science and Innovation: P.R.-C. (PID2019-110298GB-I00); X.T. (PGC2018-099645-B-I00). Generalitat de Catalunya: X.T. and P.R.-C. (2017-SGR-1602). La Caixa Foundation: X.T. and P.R.-C. (LCF/PR/HR20/52400004). Fundació la Marató de TV3: X.T. (201903-30-31-32). EMBO: L.M.F. (ALTF 2-2018)info:eu-repo/semantics/publishedVersio

The defense mechanism test-separation theme in two anxiety disorders

Two groups of 26 age- and sex-matched outpatients, with DSM-IV diagnoses of obsessive-compulsive disorder and panic disorder with agoraphobia, were compared on the Defense Mechanism Test-Separation Theme. A stimulus portraying a mother figure who is leaving a room where a baby lies alone on the floor was presented 22 times at increasing exposure durations in a single-view tachistoscope. Participants were asked to describe what they perceived at each step, according to the method of the Defense Mechanism Test. As predicted, reports of the mother seen as an inanimate object (phobic repression) were statistically significantly associated with agoraphobia, while reports of the mother entering the room or doing something other than leaving the baby (reaction formation) and reports of the baby as an angel (intellectualization) were associated with obsessive-compulsive disorder