@article{21384, abstract = {Cell migration in vivo is often guided by chemical signaling, i.e., chemotaxis. For immune cells performing chemotaxis in the organism, this process is influenced by the complex geometry of the tissue environment. In this study, we use a theoretical model of branched cell migration on a network to explore the cellular response to chemical gradients. The model predicts the response of a branched cell to a chemical gradient: how the cell reorients its internal polarity and how it navigates through a complex environment up a chemical gradient. We then compare the model’s predictions with experimental observations of neutrophils migrating to the site of a laser-inflicted wound in a zebrafish larva fin, and neutrophils migrating in vitro inside a regular lattice of pillars. We find that the model captures the details of the subcellular response to the chemokine gradient, as well as qualitative characteristics of the large-scale migration, suggesting that the neutrophils behave as fast cells, which explains the functionality of these immune cells.}, author = {Liu, Jiayi and Ron, Jonathan E. and Rinaldi, Giulia and Williantarra, Ivanna and Georgantzoglou, Antonios and de Vries, Ingrid and Sixt, Michael K and Sarris, Milka and Gov, Nir S.}, issn = {1553-7358}, journal = {PLOS Computational Biology}, number = {2}, publisher = {Public Library of Science}, title = {{Modelling chemotaxis of branched cells in complex environments provides insights into immune cell navigation}}, doi = {10.1371/journal.pcbi.1013934}, volume = {22}, year = {2026}, } @article{21707, abstract = {Structural and functional differences between brain hemispheres are a common feature of animal nervous systems with reduced bilateral asymmetry often linked to impaired cognitive performance. How neuronal left-right asymmetry is initiated and integrated into a bilaterally symmetrical ground pattern is poorly understood. Here, we show that the directional asymmetry of a Drosophila central brain circuit originates from axonal interactions of two types of bilateral pioneer neurons. Subsequent recruitment of neighboring neurons into the asymmetric neuropil primordium results in hemisphere-specific microcircuits. Circuit lateralization requires dynamic expression of the cell adhesion molecule Fasciclin 2 to maintain structural plasticity in axonal remodeling. Reduced circuit asymmetry following cell type–specific Fasciclin 2 manipulation affects adult brain function. These results reveal an unexpected degree of developmental plasticity of late-born Drosophila neurons in the formation of a circuit node via the lateralized recruitment of symmetric circuit components.}, author = {Markovitsch, Johann W. and Mitić, Daniel and Del Pilar Jiménez García, Alisa and Zane, Alsberga and Kainz, Sarah and Kaur, Rashmit and Hummel, Thomas}, issn = {2375-2548}, journal = {Science Advances}, number = {13}, publisher = {American Association for the Advancement of Science}, title = {{Sequential formation of Drosophila circuit asymmetry via prolonged structural plasticity}}, doi = {10.1126/sciadv.aea6020}, volume = {12}, year = {2026}, } @article{19928, abstract = {Patho-mechanistic origins of ulcerative colitis are still poorly understood. The actin cross-linker filamin A (FLNA) impacts cellular responses through interaction with cytosolic proteins. Posttranscriptional A-to-I editing generates two forms of FLNA: genome-encoded FLNAQ and FLNAR. FLNA is edited in colon fibroblasts, smooth muscle cells, and endothelial cells. We found that the FLNA editing status determines colitis severity. Editing was highest in healthy colons and reduced during murine and human colitis. Mice that exclusively express FLNAR were highly resistant to DSS-induced colitis, whereas fully FLNAQ animals developed severe inflammation. While the genetic induction of FLNA editing influenced transcriptional states of structural cells and microbiome composition, we found that FLNAR exerts protection specifically via myeloid cells, which are physiologically unedited. Introducing fixed FLNAR did not hamper cell migration but reduced macrophage inflammation and rendered neutrophils less prone to NETosis. Thus, loss of FLNA editing correlates with colitis severity, and targeted editing of myeloid cells serves as a novel therapeutic approach in intestinal inflammation.}, author = {Gawish, Riem and Varada, Rajagopal and Deckert, Florian and Hladik, Anastasiya and Steinbichl, Linda and Cimatti, Laura and Milanovic, Katarina and Jain, Mamta and Torgasheva, Natalya and Tanzer, Andrea and De Paepe, Kim and Van De Wiele, Tom and Hausmann, Bela and Lang, Michaela and Pechhacker, Martin and Ibrahim, Nahla and De Vries, Ingrid and Brostjan, Christine and Sixt, Michael K and Gasche, Christoph and Boon, Louis and Berry, David and Jantsch, Michael F. and Pereira, Fatima C. and Vesely, Cornelia}, issn = {1540-9538}, journal = {Journal of Experimental Medicine}, number = {9}, publisher = {Rockefeller University Press}, title = {{Filamin A editing in myeloid cells reduces intestinal inflammation and protects from colitis}}, doi = {10.1084/jem.20240109}, volume = {222}, year = {2025}, } @article{20427, abstract = {Animal cells migrating up chemotactic gradients often show speed oscillations. A new study describes a molecular circuit that switches zebrafish germ cells between phases of straight runs, tumbling and directional reorientation.}, author = {Li, Ziqiang and Sixt, Michael K}, issn = {1879-0445}, journal = {Current Biology}, number = {18}, pages = {R890--R892}, publisher = {Elsevier}, title = {{Cell migration: How animal cells run and tumble}}, doi = {10.1016/j.cub.2025.08.016}, volume = {35}, year = {2025}, } @article{19404, abstract = {Cell migration is a fundamental process during embryonic development. Most studies in vivo have focused on the migration of cells using the extracellular matrix (ECM) as their substrate for migration. In contrast, much less is known about how cells migrate on other cells, as found in early embryos when the ECM has not yet formed. Here, we show that lateral mesendoderm (LME) cells in the early zebrafish gastrula use the ectoderm as their substrate for migration. We show that the lateral ectoderm is permissive for the animal-pole-directed migration of LME cells, while the ectoderm at the animal pole halts it. These differences in permissiveness depend on the lateral ectoderm being more cohesive than the animal ectoderm, a property controlled by bone morphogenetic protein (BMP) signaling within the ectoderm. Collectively, these findings identify ectoderm tissue cohesion as one critical factor in regulating LME migration during zebrafish gastrulation.}, author = {Tavano, Ste and Brückner, David and Tasciyan, Saren and Tong, Xin and Kardos, Roland and Schauer, Alexandra and Hauschild, Robert and Heisenberg, Carl-Philipp J}, issn = {2211-1247}, journal = {Cell Reports}, number = {3}, publisher = {Elsevier}, title = {{BMP-dependent patterning of ectoderm tissue material properties modulates lateral mesendoderm cell migration during early zebrafish gastrulation}}, doi = {10.1016/j.celrep.2025.115387}, volume = {44}, year = {2025}, } @article{17459, abstract = {Atopic dermatitis (AD) is the most common chronic inflammatory skin disease worldwide. AD is a highly complex disease with different subtypes. Many elements of AD pathophysiology have been described, but if/how they interact with each other or which mechanisms are important in which patients is still unclear. Langerhans cells (LCs) are antigen-presenting cells (APCs) in the epidermis. Depending on the context, they can act either pro- or anti-inflammatory. Many different studies have investigated LCs in the context of AD and found them to be connected to all major mechanisms of AD pathophysiology. As APCs, LCs recruit other immune cells and shape the immune response, especially adaptive immunity via polarization of T cells. As sentinel cells, LCs are primary sensors of the skin microbiome and are important for the decision of immunity versus tolerance. LCs are also involved with the integrity of the skin barrier by influencing tight junctions. Finally, LCs are important cells in the neuro-immune crosstalk in the skin. In this review, we provide an overview about the many different roles of LCs in AD. Understanding LCs might bring us closer to a more complete understanding of this highly complex disease. Potentially, modulating LCs might offer new options for targeted therapies for AD patients.}, author = {Pan, Yi and Hochgerner, Mathias and Cichon, Malgorzata Anna and Benezeder, Theresa and Bieber, Thomas and Wolf, Peter}, issn = {1468-3083}, journal = {Journal of the European Academy of Dermatology and Venereology}, number = {2}, pages = {278--289}, publisher = {Wiley}, title = {{Langerhans cells: Central players in the pathophysiology of atopic dermatitis}}, doi = {10.1111/jdv.20291}, volume = {39}, year = {2025}, } @unpublished{21427, abstract = {While tumor malignancy has been extensively studied under the prism of genetic and epigenetic heterogeneity, tumor cell states also critically depend on reciprocal interactions with the microenvironment. This raises the hitherto untested possibility that heterogeneity of the untransformed tumor stroma can actively fuel malignant progression. As biological heterogeneity is inherently difficult to control, we adopted a reductionist approach and let tumor cells invade micro-engineered environments harboring obstacles with precision-controlled geometry. We find that not only the presence of obstacles, but more surprisingly their spatial disorder, causes a drastic shift from a collective to a single-cell mode of invasion – comparable in strength to cadherin loss. Combining live-imaging and perturbation experiments with minimal biophysical modeling, we demonstrate that cell detachments result both from local geometrical constraints and a global integration of spatial disorder over time. We show that different types of microenvironments map onto different universality classes of invasion dynamics - homogeneous substrates follow Kardar–Parisi–Zhang (KPZ) scaling, while disordered ones exhibit exponents consistent with KPZ with quenched disorder (KPZq). Our findings highlight generic physical principles for how the mode of cancer cell invasion depends on environmental heterogeneity, with potential implications to understand tumor evolution in vivo.}, author = {Dunajova, Zuzana and Tasciyan, Saren and Majek, Juraj and Merrin, Jack and Sahai, Erik and Sixt, Michael K and Hannezo, Edouard B}, publisher = {bioRxiv}, title = {{Substrate heterogeneity promotes cancer cell dissemination through interface roughening}}, doi = {10.1101/2025.05.20.655037}, year = {2025}, } @article{20082, abstract = {Efficient immune responses rely on the capacity of leukocytes to traverse diverse and complex tissues. To meet such changing environmental conditions, leukocytes usually adopt an ameboid configuration, using their forward-positioned nucleus as a probe to identify and follow the path of least resistance among pre-existing pores. We show that, in dense environments where even the largest pores preclude free passage, leukocytes position their nucleus behind the centrosome and organelles. The local compression imposed on the cell body by its surroundings triggers assembly of a central F-actin pool, located between cell front and nucleus. Central actin pushes outward to transiently dilate a path for organelles and nucleus. Pools of central and front actin are tightly coupled and experimental depletion of the central pool enhances actin accumulation and protrusion formation at the cell front. Although this shifted balance speeds up cells in permissive environments, migration in restrictive environments is impaired, as the unleashed leading edge dissociates from the trapped cell body. Our findings establish an actin regulatory loop that balances path dilation with advancement of the leading edge to maintain cellular coherence.}, author = {Dos Reis Rodrigues, Patricia and Avellaneda Sarrió, Mario and Canigova, Nikola and Gärtner, Florian R and Vaahtomeri, Kari and Riedl, Michael and De Vries, Ingrid and Merrin, Jack and Hauschild, Robert and Fukui, Yoshinori and Juanes Garcia, Alba and Sixt, Michael K}, issn = {1529-2916}, journal = {Nature Immunology}, pages = {1258–1266}, publisher = {Springer Nature}, title = {{Migrating immune cells globally coordinate protrusive forces}}, doi = {10.1038/s41590-025-02211-w}, volume = {26}, year = {2025}, } @phdthesis{20149, abstract = {Immune responses depend on the coordinated and efficient migration of leukocytes. These cells, which are embedded and tightly confined within tissues, must navigate and traverse diverse and complex three-dimensional environments. Leukocytes adapt their locomotory behavior to the mechanical, geometrical, and biochemical characteristics of their surroundings. In low-density environments, where the pore size of the interstitial matrix allows free passage, these cells position the nucleus directly behind the lamellipodium, the protrusive actin structure that forms the leading front of the cell. In this configuration, they use the nucleus as a gauge to identify the path of least resistance. Here, we show that in high-density environments, where the pore size precludes free passage of the cell body, leukocytes reposition the microtubule-organizing center (MTOC) and associated organelles in front of the nucleus. In this configuration, they use actin structures protruding orthogonally to the direction of migration in order to open a path for the cell body. We identify two distinct actin populations that serve this purpose at different subcellular localizations. At the leading edge, local indentation of the plasma membrane leads to recruitment of the Wiskott-Aldrich syndrome protein (WASp), which, via Arp2/3, results in the formation of individual actin foci. At the cell body, actin polymerization is triggered by DOCK8, a Cdc42 exchange factor, resulting in the formation of a central actin pool. We demonstrate that the central and peripheral actin pools are functionally communicating and that depletion of the central actin pool leads to increased actin accumulation at the cell front, resulting in excessive extension of the leading edge.}, author = {Dos Reis Rodrigues, Patricia}, issn = {2663-337X}, pages = {114}, publisher = {Institute of Science and Technology Austria}, title = {{Coordination of protrusive forces in immune cell migration }}, doi = {10.15479/AT-ISTA-20149}, year = {2025}, } @article{20289, abstract = {Cell and tissue movement in development, cancer invasion, and immune response relies on chemical or mechanical guidance cues. In many systems, this behavior is locally directed by self-generated signaling gradients rather than long-range, prepatterned cues. However, how heterogeneous mixtures of cells interact nonreciprocally and navigate through self-generated gradients remains largely unexplored. Here, we introduce a theoretical framework for the self-organized chemotaxis of heterogeneous cell populations. We find that the relative chemotactic sensitivities of different cell populations control their long-time coupling and comigration dynamics, with boundary conditions such as external cell and attractant reservoirs substantially influencing the migration patterns. Our model predicts an optimal parameter regime that enables robust and colocalized migration. We test our theoretical predictions with in vitro experiments demonstrating the comigration of distinct immune cell populations, and quantitatively reproduce observed migration patterns under wild-type and perturbed conditions. Interestingly, immune cell comigration occurs close to the predicted optimal regime. Finally, we incorporate mechanical interactions into our framework, revealing a nontrivial interplay between chemotactic and mechanical nonreciprocity in driving collective migration. Together, our findings suggest that self-generated chemotaxis is a robust strategy for the navigation of mixed cell populations.}, author = {Ucar, Mehmet C and Zane, Alsberga and Alanko, Jonna H and Sixt, Michael K and Hannezo, Edouard B}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences}, number = {34}, publisher = {National Academy of Sciences}, title = {{Self-generated chemotaxis of mixed cell populations}}, doi = {10.1073/pnas.2504064122}, volume = {122}, year = {2025}, } @phdthesis{19745, abstract = {Cell migration is a crucial process in animal development and maintenance. It is incredibly heterogeneous, with different cell types utilizing fundamentally distinct migration strategies. The strategies also depend on the cellular microenvironment, where cells can switch between migration modes as they encounter new environmental cues. In this thesis, we investigated how dendritic cells adapt their migration strategy when encountering geometrically, mechanically and chemically distinct environments. When dendritic cells are embedded in a homogeneous fibrous network, they migrate in a fast and directional amoeboid manner. In this migration strategy, extracellular proteolysis and integrin-mediated adhesions are dispensable. Instead, the cells use topography of the environment to propel their cell body forward. To migrate efficiently in the maze of different pore sizes, they position the nucleus ahead of the microtubule organizing center (MTOC) and use it to gauge the pores to identify the path of least resistance. Our aim was to identify whether dendritic cells adapt their migration strategy when encountering asymmetrical transitions into much denser environments with limited choice of large pores. In such invasive transitions it is unclear if the cells can cross tight pores without the use of adhesions and extracellular proteolysis and whether they maintain the nucleus in the cell front. Using various cell migration assays such as fibrous 3D collagen gels, geometrically defined microchannels with constrictions and simplistic under agarose migration assay, we provide a comprehensive characterization of invasive migration of dendritic cells. We show that during invasion the cells stall and stretch, reflecting the difficulty to translocate the bulky cell body into the dense environment. In collagen gels, we show that dendritic cells can invade without proteolysis and adhesions. Instead, they utilize contractility, which can lead to largescale collagen compressions. During invasion, the nucleus stalls at tight constrictions, leading to a transient organelle reorientation. To resolve the stalling, upregulated rear contractility is required. This contractile force is simultaneously necessary for reverting the nucleus back to the cell front after invasion and maintaining this positioning during permissive migration. A functional role of the reorientation was uncovered in the first collaboration project. A prominent central actin pool was identified around the MTOC, especially pronounced in dense and compressive environments. The actin pool was shown to generate pushing forces to dilate the space for cell translocation. These forces are only necessary in non-permissive environments, where the nucleus reorients to the cell rear, allowing the actin pool to generate space. In permissive environments where space generation is dispensable, the MTOC is located behind the nucleus and the actin cloud has reduced intensity, allowing more actin to be incorporated into the lamellipodium, speeding up migration. In the second collaboration project, we investigated the effects of distinct chemical environments on dendritic cell migration. The strikingly persistent migration of these cells was explained by their ability to modulate and even self-generate chemokine gradients. This allows the cells to migrate faster and more persistent in uniform chemokine fields compared to imposed chemokine gradients. The chemokine receptor CCR7 was identified as a crucial player in this process, both sensing the signal and internalizing the chemokine to create a sink.}, author = {Canigova, Nikola}, isbn = {978-3-99078-058-9}, issn = {2663-337X}, pages = {133}, publisher = {Institute of Science and Technology Austria}, title = {{Adaptive strategies of dendritic cell migration in response to environmental cues}}, doi = {10.15479/AT-ISTA-19745}, year = {2025}, } @article{18109, abstract = {Venous thromboembolism (VTE) is a common, deadly disease with an increasing incidence despite preventive efforts. Clinical observations have associated elevated antibody concentrations or antibody-based therapies with thrombotic events. However, how antibodies contribute to thrombosis is unknown. Here, we show that reduced blood flow enabled immunoglobulin M (IgM) to bind to FcμR and the polymeric immunoglobulin receptor (pIgR), initiating endothelial activation and platelet recruitment. Subsequently, the procoagulant surface of activated platelets accommodated antigen- and FcγR-independent IgG deposition. This leads to classical complement activation, setting in motion a prothrombotic vicious circle. Key elements of this mechanism were present in humans in the setting of venous stasis as well as in the dysregulated immunothrombosis of COVID-19. This antibody-driven thrombosis can be prevented by pharmacologically targeting complement. Hence, our results uncover antibodies as previously unrecognized central regulators of thrombosis. These findings carry relevance for therapeutic application of antibodies and open innovative avenues to target thrombosis without compromising hemostasis.}, author = {Stark, Konstantin and Kilani, Badr and Stockhausen, Sven and Busse, Johanna and Schubert, Irene and Tran, Thuy Duong and Gärtner, Florian R and Leunig, Alexander and Pekayvaz, Kami and Nicolai, Leo and Fumagalli, Valeria and Stermann, Julia and Stephan, Felix and David, Christian and Müller, Martin B. and Heyman, Birgitta and Lux, Anja and Da Palma Guerreiro, Alexandra and Frenzel, Lukas P. and Schmidt, Christoph Q. and Dopler, Arthur and Moser, Markus and Chandraratne, Sue and Von Brühl, Marie Luise and Lorenz, Michael and Korff, Thomas and Rudelius, Martina and Popp, Oliver and Kirchner, Marieluise and Mertins, Philipp and Nimmerjahn, Falk and Iannacone, Matteo and Sperandio, Markus and Engelmann, Bernd and Verschoor, Admar and Massberg, Steffen}, issn = {1097-4180}, journal = {Immunity}, number = {9}, pages = {2140--2156}, publisher = {Elsevier}, title = {{Antibodies and complement are key drivers of thrombosis}}, doi = {10.1016/j.immuni.2024.08.007}, volume = {57}, year = {2024}, } @article{14846, abstract = {Contraction and flow of the actin cell cortex have emerged as a common principle by which cells reorganize their cytoplasm and take shape. However, how these cortical flows interact with adjacent cytoplasmic components, changing their form and localization, and how this affects cytoplasmic organization and cell shape remains unclear. Here we show that in ascidian oocytes, the cooperative activities of cortical actomyosin flows and deformation of the adjacent mitochondria-rich myoplasm drive oocyte cytoplasmic reorganization and shape changes following fertilization. We show that vegetal-directed cortical actomyosin flows, established upon oocyte fertilization, lead to both the accumulation of cortical actin at the vegetal pole of the zygote and compression and local buckling of the adjacent elastic solid-like myoplasm layer due to friction forces generated at their interface. Once cortical flows have ceased, the multiple myoplasm buckles resolve into one larger buckle, which again drives the formation of the contraction pole—a protuberance of the zygote’s vegetal pole where maternal mRNAs accumulate. Thus, our findings reveal a mechanism where cortical actomyosin network flows determine cytoplasmic reorganization and cell shape by deforming adjacent cytoplasmic components through friction forces.}, author = {Caballero Mancebo, Silvia and Shinde, Rushikesh and Bolger-Munro, Madison and Peruzzo, Matilda and Szep, Gregory and Steccari, Irene and Labrousse Arias, David and Zheden, Vanessa and Merrin, Jack and Callan-Jones, Andrew and Voituriez, Raphaël and Heisenberg, Carl-Philipp J}, issn = {1745-2481}, journal = {Nature Physics}, pages = {310--321}, publisher = {Springer Nature}, title = {{Friction forces determine cytoplasmic reorganization and shape changes of ascidian oocytes upon fertilization}}, doi = {10.1038/s41567-023-02302-1}, volume = {20}, year = {2024}, } @article{14933, abstract = {Centrioles are part of centrosomes and cilia, which are microtubule organising centres (MTOC) with diverse functions. Despite their stability, centrioles can disappear during differentiation, such as in oocytes, but little is known about the regulation of their structural integrity. Our previous research revealed that the pericentriolar material (PCM) that surrounds centrioles and its recruiter, Polo kinase, are downregulated in oogenesis and sufficient for maintaining both centrosome structural integrity and MTOC activity. We now show that the expression of specific components of the centriole cartwheel and wall, including ANA1/CEP295, is essential for maintaining centrosome integrity. We find that Polo kinase requires ANA1 to promote centriole stability in cultured cells and eggs. In addition, ANA1 expression prevents the loss of centrioles observed upon PCM-downregulation. However, the centrioles maintained by overexpressing and tethering ANA1 are inactive, unlike the MTOCs observed upon tethering Polo kinase. These findings demonstrate that several centriole components are needed to maintain centrosome structure. Our study also highlights that centrioles are more dynamic than previously believed, with their structural stability relying on the continuous expression of multiple components.}, author = {Pimenta-Marques, Ana and Perestrelo, Tania and Dos Reis Rodrigues, Patricia and Duarte, Paulo and Ferreira-Silva, Ana and Lince-Faria, Mariana and Bettencourt-Dias, Mónica}, issn = {1469-3178}, journal = {EMBO Reports}, number = {1}, pages = {102--127}, publisher = {Embo Press}, title = {{Ana1/CEP295 is an essential player in the centrosome maintenance program regulated by Polo kinase and the PCM}}, doi = {10.1038/s44319-023-00020-6}, volume = {25}, year = {2024}, } @article{15146, abstract = {The extracellular matrix (ECM) serves as a scaffold for cells and plays an essential role in regulating numerous cellular processes, including cell migration and proliferation. Due to limitations in specimen preparation for conventional room-temperature electron microscopy, we lack structural knowledge on how ECM components are secreted, remodeled, and interact with surrounding cells. We have developed a 3D-ECM platform compatible with sample thinning by cryo-focused ion beam milling, the lift-out extraction procedure, and cryo-electron tomography. Our workflow implements cell-derived matrices (CDMs) grown on EM grids, resulting in a versatile tool closely mimicking ECM environments. This allows us to visualize ECM for the first time in its hydrated, native context. Our data reveal an intricate network of extracellular fibers, their positioning relative to matrix-secreting cells, and previously unresolved structural entities. Our workflow and results add to the structural atlas of the ECM, providing novel insights into its secretion and assembly.}, author = {Zens, Bettina and Fäßler, Florian and Hansen, Jesse and Hauschild, Robert and Datler, Julia and Hodirnau, Victor-Valentin and Zheden, Vanessa and Alanko, Jonna H and Sixt, Michael K and Schur, Florian KM}, issn = {1540-8140}, journal = {Journal of Cell Biology}, number = {6}, publisher = {Rockefeller University Press}, title = {{Lift-out cryo-FIBSEM and cryo-ET reveal the ultrastructural landscape of extracellular matrix}}, doi = {10.1083/jcb.202309125}, volume = {223}, year = {2024}, } @article{15408, abstract = {Background: IgE-mediated degranulation of mast cells (MCs) provides rapid protection against environmental hazards, including animal venoms. A fraction of tissue-resident MCs intimately associates with blood vessels. These perivascular MCs were reported to extend projections into the vessel lumen and to be the first MCs to acquire intravenously injected IgE, suggesting that IgE loading of MCs depends on their vascular association. Objective: We sought to elucidate the molecular basis of the MC–blood vessel interaction and to determine its relevance for IgE-mediated immune responses. Methods: We selectively inactivated the Itgb1 gene, encoding the β1 chain of integrin adhesion molecules (ITGB1), in MCs by conditional gene targeting in mice. We analyzed skin MCs for blood vessel association, surface IgE density, and capability to bind circulating antibody specific for MC surface molecules, as well as in vivo responses to antigen administered via different routes. Results: Lack of ITGB1 expression severely compromised MC–blood vessel association. ITGB1-deficient MCs showed normal densities of surface IgE but reduced binding of intravenously injected antibodies. While their capacity to degranulate in response to IgE ligation in vivo was unimpaired, anaphylactic responses to antigen circulating in the vasculature were largely abolished. Conclusions: ITGB1-mediated association of MCs with blood vessels is key for MC immune surveillance of blood vessel content, but is dispensable for slow steady-state loading of endogenous IgE onto tissue-resident MCs.}, author = {Link, Kristina and Muhandes, Lina and Polikarpova, Anastasia and Lämmermann, Tim and Sixt, Michael K and Fässler, Reinhard and Roers, Axel}, issn = {1097-6825}, journal = {Journal of Allergy and Clinical Immunology}, number = {3}, pages = {745--753}, publisher = {Elsevier}, title = {{Integrin β1–mediated mast cell immune-surveillance of blood vessel content}}, doi = {10.1016/j.jaci.2024.03.022}, volume = {154}, year = {2024}, } @article{17191, abstract = {Dendritic cells migrate to and from lymph nodes in response to chemokine gradients.Data now show that steady-state migration of these cells can be triggered by a mechanosensitive pathway.}, author = {Lembo, Sergio and Sixt, Michael K}, issn = {1529-2916}, journal = {Nature Immunology}, pages = {1131–1132 }, publisher = {Springer Nature}, title = {{Nuclear squeezing wakes up dendritic cells}}, doi = {10.1038/s41590-024-01881-2}, volume = {25}, year = {2024}, } @article{17233, abstract = {CRISPR-Cas9 technology has become an essential tool for plant genome editing. Recent advancements have significantly improved the ability to target multiple genes simultaneously within the same genetic background through various strategies. Additionally, there has been significant progress in developing methods for inducible or tissue-specific editing. These advancements offer numerous possibilities for tailored genome modifications. Building upon existing research, we have developed an optimized and modular strategy allowing the targeting of several genes simultaneously in combination with the synchronized expression of the Cas9 endonuclease in the egg cell. This system allows significant editing efficiency while avoiding mosaicism. In addition, the versatile system we propose allows adaptation to inducible and/or tissue-specific edition according to the promoter chosen to drive the expression of the Cas9 gene. Here, we describe a step-by-step protocol for generating the binary vector necessary for establishing Arabidopsis edited lines using a versatile cloning strategy that combines Gateway® and Golden Gate technologies. We describe a versatile system that allows the cloning of as many guides as needed to target DNA, which can be multiplexed into a polycistronic gene and combined in the same construct with sequences for the expression of the Cas9 endonuclease. The expression of Cas9 is controlled by selecting from among a collection of promoters, including constitutive, inducible, ubiquitous, or tissue-specific promoters. Only one vector containing the polycistronic gene (tRNA-sgRNA) needs to be constructed. For that, sgRNA (composed of protospacers chosen to target the gene of interest and sgRNA scaffold) is cloned in tandem with the pre-tRNA sequence. Then, a single recombination reaction is required to assemble the promoter, the zCas9 coding sequence, and the tRNA-gRNA polycistronic gene. Each element is cloned in an entry vector and finally assembled according to the Multisite Gateway® Technology. Here, we detail the process to express zCas9 under the control of egg cell promoter fused to enhancer sequence (EC1.2en-EC1.1p) and to simultaneously target two multiple C2 domains and transmembrane region protein genes (MCTP3 and MCTP4, respectively at3g57880 and at1g51570), using one or two sgRNA per gene.}, author = {Li, Ziqiang and Huard, Jennifer and Bayer, Emmanuelle M. and Wattelet-Boyer, Valérie}, issn = {2331-8325}, journal = {Bio-protocol}, number = {13}, publisher = {Bio-Protocol}, title = {{Versatile cloning strategy for efficient multigene editing in Arabidopsis}}, doi = {10.21769/BioProtoc.5029}, volume = {14}, year = {2024}, } @article{17279, abstract = {In a recent issue of Cell, Zhang et al.1 demonstrate that mechanical features of a solid tumor can drive T cells into dysfunctionality and identify pathways that revert this “exhausted” state.}, author = {Avellaneda Sarrió, Mario and Sixt, Michael K}, issn = {2451-9448}, journal = {Cell Chemical Biology}, number = {7}, pages = {1242--1243}, publisher = {Elsevier}, title = {{Rescuing T cells from stiff tumors}}, doi = {10.1016/j.chembiol.2024.06.011}, volume = {31}, year = {2024}, } @article{17284, abstract = {Platelet homeostasis is essential for vascular integrity and immune defence1,2. Although the process of platelet formation by fragmenting megakaryocytes (MKs; thrombopoiesis) has been extensively studied, the cellular and molecular mechanisms required to constantly replenish the pool of MKs by their progenitor cells (megakaryopoiesis) remains unclear3,4. Here we use intravital imaging to track the cellular dynamics of megakaryopoiesis over days. We identify plasmacytoid dendritic cells (pDCs) as homeostatic sensors that monitor the bone marrow for apoptotic MKs and deliver IFNα to the MK niche triggering local on-demand proliferation and maturation of MK progenitors. This pDC-dependent feedback loop is crucial for MK and platelet homeostasis at steady state and under stress. pDCs are best known for their ability to function as vigilant detectors of viral infection5. We show that virus-induced activation of pDCs interferes with their function as homeostatic sensors of megakaryopoiesis. Consequently, activation of pDCs by SARS-CoV-2 leads to excessive megakaryopoiesis. Together, we identify a pDC-dependent homeostatic circuit that involves innate immune sensing and demand-adapted release of inflammatory mediators to maintain homeostasis of the megakaryocytic lineage.}, author = {Gärtner, Florian R and Ishikawa-Ankerhold, Hellen and Stutte, Susanne and Fu, Wenwen and Weitz, Jutta and Dueck, Anne and Nelakuditi, Bhavishya and Fumagalli, Valeria and Van Den Heuvel, Dominic and Belz, Larissa and Sobirova, Gulnoza and Zhang, Zhe and Titova, Anna and Navarro, Alejandro Martinez and Pekayvaz, Kami and Lorenz, Michael and Von Baumgarten, Louisa and Kranich, Jan and Straub, Tobias and Popper, Bastian and Zheden, Vanessa and Kaufmann, Walter and Guo, Chenglong and Piontek, Guido and Von Stillfried, Saskia and Boor, Peter and Colonna, Marco and Clauß, Sebastian and Schulz, Christian and Brocker, Thomas and Walzog, Barbara and Scheiermann, Christoph and Aird, William C. and Nerlov, Claus and Stark, Konstantin and Petzold, Tobias and Engelhardt, Stefan and Sixt, Michael K and Hauschild, Robert and Rudelius, Martina and Oostendorp, Robert A.J. and Iannacone, Matteo and Heinig, Matthias and Massberg, Steffen}, issn = {1476-4687}, journal = {Nature}, pages = {645--653}, publisher = {Springer Nature}, title = {{Plasmacytoid dendritic cells control homeostasis of megakaryopoiesis}}, doi = {10.1038/s41586-024-07671-y}, volume = {631}, year = {2024}, }