@phdthesis{8589, abstract = {The plant hormone auxin plays indispensable roles in plant growth and development. An essential level of regulation in auxin action is the directional auxin transport within cells. The establishment of auxin gradient in plant tissue has been attributed to local auxin biosynthesis and directional intercellular auxin transport, which both are controlled by various environmental and developmental signals. It is well established that asymmetric auxin distribution in cells is achieved by polarly localized PIN-FORMED (PIN) auxin efflux transporters. Despite the initial insights into cellular mechanisms of PIN polarization obtained from the last decades, the molecular mechanism and specific regulators mediating PIN polarization remains elusive. In this thesis, we aim to find novel players in PIN subcellular polarity regulation during Arabidopsis development. We first characterize the physiological effect of piperonylic acid (PA) on Arabidopsis hypocotyl gravitropic bending and PIN polarization. Secondly, we reveal the importance of SCFTIR1/AFB auxin signaling pathway in shoot gravitropism bending termination. In addition, we also explore the role of myosin XI complex, and actin cytoskeleton in auxin feedback regulation on PIN polarity. In Chapter 1, we give an overview of the current knowledge about PIN-mediated auxin fluxes in various plant tropic responses. In Chapter 2, we study the physiological effect of PA on shoot gravitropic bending. Our results show that PA treatment inhibits auxin-mediated PIN3 repolarization by interfering with PINOID and PIN3 phosphorylation status, ultimately leading to hyperbending hypocotyls. In Chapter 3, we provide evidence to show that the SCFTIR1/AFB nuclear auxin signaling pathway is crucial and required for auxin-mediated PIN3 repolarization and shoot gravitropic bending termination. In Chapter 4, we perform a phosphoproteomics approach and identify the motor protein Myosin XI and its binding protein, the MadB2 family, as an essential regulator of PIN polarity for auxin-canalization related developmental processes. In Chapter 5, we demonstrate the vital role of actin cytoskeleton in auxin feedback on PIN polarity by regulating PIN subcellular trafficking. Overall, the data presented in this PhD thesis brings novel insights into the PIN polar localization regulation that resulted in the (re)establishment of the polar auxin flow and gradient in response to environmental stimuli during plant development.}, author = {Han, Huibin}, issn = {2663-337X}, pages = {164}, publisher = {Institute of Science and Technology Austria}, title = {{Novel insights into PIN polarity regulation during Arabidopsis development}}, doi = {10.15479/AT:ISTA:8589}, year = {2020}, } @phdthesis{8657, abstract = {Synthesis of proteins – translation – is a fundamental process of life. Quantitative studies anchor translation into the context of bacterial physiology and reveal several mathematical relationships, called “growth laws,” which capture physiological feedbacks between protein synthesis and cell growth. Growth laws describe the dependency of the ribosome abundance as a function of growth rate, which can change depending on the growth conditions. Perturbations of translation reveal that bacteria employ a compensatory strategy in which the reduced translation capability results in increased expression of the translation machinery. Perturbations of translation are achieved in various ways; clinically interesting is the application of translation-targeting antibiotics – translation inhibitors. The antibiotic effects on bacterial physiology are often poorly understood. Bacterial responses to two or more simultaneously applied antibiotics are even more puzzling. The combined antibiotic effect determines the type of drug interaction, which ranges from synergy (the effect is stronger than expected) to antagonism (the effect is weaker) and suppression (one of the drugs loses its potency). In the first part of this work, we systematically measure the pairwise interaction network for translation inhibitors that interfere with different steps in translation. We find that the interactions are surprisingly diverse and tend to be more antagonistic. To explore the underlying mechanisms, we begin with a minimal biophysical model of combined antibiotic action. We base this model on the kinetics of antibiotic uptake and binding together with the physiological response described by the growth laws. The biophysical model explains some drug interactions, but not all; it specifically fails to predict suppression. In the second part of this work, we hypothesize that elusive suppressive drug interactions result from the interplay between ribosomes halted in different stages of translation. To elucidate this putative mechanism of drug interactions between translation inhibitors, we generate translation bottlenecks genetically using in- ducible control of translation factors that regulate well-defined translation cycle steps. These perturbations accurately mimic antibiotic action and drug interactions, supporting that the interplay of different translation bottlenecks partially causes these interactions. We extend this approach by varying two translation bottlenecks simultaneously. This approach reveals the suppression of translocation inhibition by inhibited translation. We rationalize this effect by modeling dense traffic of ribosomes that move on transcripts in a translation factor-mediated manner. This model predicts a dissolution of traffic jams caused by inhibited translocation when the density of ribosome traffic is reduced by lowered initiation. We base this model on the growth laws and quantitative relationships between different translation and growth parameters. In the final part of this work, we describe a set of tools aimed at quantification of physiological and translation parameters. We further develop a simple model that directly connects the abundance of a translation factor with the growth rate, which allows us to extract physiological parameters describing initiation. We demonstrate the development of tools for measuring translation rate. This thesis showcases how a combination of high-throughput growth rate mea- surements, genetics, and modeling can reveal mechanisms of drug interactions. Furthermore, by a gradual transition from combinations of antibiotics to precise genetic interventions, we demonstrated the equivalency between genetic and chemi- cal perturbations of translation. These findings tile the path for quantitative studies of antibiotic combinations and illustrate future approaches towards the quantitative description of translation.}, author = {Kavcic, Bor}, isbn = {978-3-99078-011-4}, issn = {2663-337X}, pages = {271}, publisher = {Institute of Science and Technology Austria}, title = {{Perturbations of protein synthesis: from antibiotics to genetics and physiology}}, doi = {10.15479/AT:ISTA:8657}, year = {2020}, } @article{8721, abstract = {Spontaneously arising channels that transport the phytohormone auxin provide positional cues for self-organizing aspects of plant development such as flexible vasculature regeneration or its patterning during leaf venation. The auxin canalization hypothesis proposes a feedback between auxin signaling and transport as the underlying mechanism, but molecular players await discovery. We identified part of the machinery that routes auxin transport. The auxin-regulated receptor CAMEL (Canalization-related Auxin-regulated Malectin-type RLK) together with CANAR (Canalization-related Receptor-like kinase) interact with and phosphorylate PIN auxin transporters. camel and canar mutants are impaired in PIN1 subcellular trafficking and auxin-mediated PIN polarization, which macroscopically manifests as defects in leaf venation and vasculature regeneration after wounding. The CAMEL-CANAR receptor complex is part of the auxin feedback that coordinates polarization of individual cells during auxin canalization.}, author = {Hajny, Jakub and Prat, Tomas and Rydza, N and Rodriguez Solovey, Lesia and Tan, Shutang and Verstraeten, Inge and Domjan, David and Mazur, E and Smakowska-Luzan, E and Smet, W and Mor, E and Nolf, J and Yang, B and Grunewald, W and Molnar, Gergely and Belkhadir, Y and De Rybel, B and Friml, Jiří}, issn = {1095-9203}, journal = {Science}, number = {6516}, pages = {550--557}, publisher = {American Association for the Advancement of Science}, title = {{Receptor kinase module targets PIN-dependent auxin transport during canalization}}, doi = {10.1126/science.aba3178}, volume = {370}, year = {2020}, } @article{8737, abstract = {Mitochondrial complex I couples NADH:ubiquinone oxidoreduction to proton pumping by an unknown mechanism. Here, we present cryo-electron microscopy structures of ovine complex I in five different conditions, including turnover, at resolutions up to 2.3 to 2.5 angstroms. Resolved water molecules allowed us to experimentally define the proton translocation pathways. Quinone binds at three positions along the quinone cavity, as does the inhibitor rotenone that also binds within subunit ND4. Dramatic conformational changes around the quinone cavity couple the redox reaction to proton translocation during open-to-closed state transitions of the enzyme. In the induced deactive state, the open conformation is arrested by the ND6 subunit. We propose a detailed molecular coupling mechanism of complex I, which is an unexpected combination of conformational changes and electrostatic interactions.}, author = {Kampjut, Domen and Sazanov, Leonid A}, issn = {10959203}, journal = {Science}, number = {6516}, publisher = {American Association for the Advancement of Science}, title = {{The coupling mechanism of mammalian respiratory complex I}}, doi = {10.1126/science.abc4209}, volume = {370}, year = {2020}, } @article{8943, abstract = {The widely used non-steroidal anti-inflammatory drugs (NSAIDs) are derivatives of the phytohormone salicylic acid (SA). SA is well known to regulate plant immunity and development, whereas there have been few reports focusing on the effects of NSAIDs in plants. Our studies here reveal that NSAIDs exhibit largely overlapping physiological activities to SA in the model plant Arabidopsis. NSAID treatments lead to shorter and agravitropic primary roots and inhibited lateral root organogenesis. Notably, in addition to the SA-like action, which in roots involves binding to the protein phosphatase 2A (PP2A), NSAIDs also exhibit PP2A-independent effects. Cell biological and biochemical analyses reveal that many NSAIDs bind directly to and inhibit the chaperone activity of TWISTED DWARF1, thereby regulating actin cytoskeleton dynamics and subsequent endosomal trafficking. Our findings uncover an unexpected bioactivity of human pharmaceuticals in plants and provide insights into the molecular mechanism underlying the cellular action of this class of anti-inflammatory compounds.}, author = {Tan, Shutang and Di Donato, Martin and Glanc, Matous and Zhang, Xixi and Klíma, Petr and Liu, Jie and Bailly, Aurélien and Ferro, Noel and Petrášek, Jan and Geisler, Markus and Friml, Jiří}, issn = {22111247}, journal = {Cell Reports}, number = {9}, publisher = {Elsevier}, title = {{Non-steroidal anti-inflammatory drugs target TWISTED DWARF1-regulated actin dynamics and auxin transport-mediated plant development}}, doi = {10.1016/j.celrep.2020.108463}, volume = {33}, year = {2020}, } @article{8971, abstract = {The actin-related protein (Arp)2/3 complex nucleates branched actin filament networks pivotal for cell migration, endocytosis and pathogen infection. Its activation is tightly regulated and involves complex structural rearrangements and actin filament binding, which are yet to be understood. Here, we report a 9.0 Å resolution structure of the actin filament Arp2/3 complex branch junction in cells using cryo-electron tomography and subtomogram averaging. This allows us to generate an accurate model of the active Arp2/3 complex in the branch junction and its interaction with actin filaments. Notably, our model reveals a previously undescribed set of interactions of the Arp2/3 complex with the mother filament, significantly different to the previous branch junction model. Our structure also indicates a central role for the ArpC3 subunit in stabilizing the active conformation.}, author = {Fäßler, Florian and Dimchev, Georgi A and Hodirnau, Victor-Valentin and Wan, William and Schur, Florian KM}, issn = {2041-1723}, journal = {Nature Communications}, keywords = {General Biochemistry, Genetics and Molecular Biology, General Physics and Astronomy, General Chemistry}, publisher = {Springer Nature}, title = {{Cryo-electron tomography structure of Arp2/3 complex in cells reveals new insights into the branch junction}}, doi = {10.1038/s41467-020-20286-x}, volume = {11}, year = {2020}, } @phdthesis{8983, abstract = {Metabolic adaptation is a critical feature of migrating cells. It tunes the metabolic programs of migrating cells to allow them to efficiently exert their crucial roles in development, inflammatory responses and tumor metastasis. Cell migration through physically challenging contexts requires energy. However, how the metabolic reprogramming that underlies in vivo cell invasion is controlled is still unanswered. In my PhD project, I identify a novel conserved metabolic shift in Drosophila melanogaster immune cells that by modulating their bioenergetic potential controls developmentally programmed tissue invasion. We show that this regulation requires a novel conserved nuclear protein, named Atossa. Atossa enhances the transcription of a set of proteins, including an RNA helicase Porthos and two metabolic enzymes, each of which increases the tissue invasion of leading Drosophila macrophages and can rescue the atossa mutant phenotype. Porthos selectively regulates the translational efficiency of a subset of mRNAs containing a 5’-UTR cis-regulatory TOP-like sequence. These 5’TOPL mRNA targets encode mitochondrial-related proteins, including subunits of mitochondrial oxidative phosphorylation (OXPHOS) components III and V and other metabolic-related proteins. Porthos powers up mitochondrial OXPHOS to engender a sufficient ATP supply, which is required for tissue invasion of leading macrophages. Atossa’s two vertebrate orthologs rescue the invasion defect. In my PhD project, I elucidate that Atossa displays a conserved developmental metabolic control to modulate metabolic capacities and the cellular energy state, through altered transcription and translation, to aid the tissue infiltration of leading cells into energy demanding barriers.}, author = {Emtenani, Shamsi}, issn = {2663-337X}, pages = {141}, publisher = {Institute of Science and Technology Austria}, title = {{Metabolic regulation of Drosophila macrophage tissue invasion}}, doi = {10.15479/AT:ISTA:8983}, year = {2020}, } @article{7343, abstract = {Coinfections with multiple pathogens can result in complex within‐host dynamics affecting virulence and transmission. While multiple infections are intensively studied in solitary hosts, it is so far unresolved how social host interactions interfere with pathogen competition, and if this depends on coinfection diversity. We studied how the collective disease defences of ants – their social immunity – influence pathogen competition in coinfections of same or different fungal pathogen species. Social immunity reduced virulence for all pathogen combinations, but interfered with spore production only in different‐species coinfections. Here, it decreased overall pathogen sporulation success while increasing co‐sporulation on individual cadavers and maintaining a higher pathogen diversity at the community level. Mathematical modelling revealed that host sanitary care alone can modulate competitive outcomes between pathogens, giving advantage to fast‐germinating, thus less grooming‐sensitive ones. Host social interactions can hence modulate infection dynamics in coinfected group members, thereby altering pathogen communities at the host level and population level.}, author = {Milutinovic, Barbara and Stock, Miriam and Grasse, Anna V and Naderlinger, Elisabeth and Hilbe, Christian and Cremer, Sylvia}, issn = {1461-0248}, journal = {Ecology Letters}, number = {3}, pages = {565--574}, publisher = {Wiley}, title = {{Social immunity modulates competition between coinfecting pathogens}}, doi = {10.1111/ele.13458}, volume = {23}, year = {2020}, } @article{7427, abstract = {Plants, like other multicellular organisms, survive through a delicate balance between growth and defense against pathogens. Salicylic acid (SA) is a major defense signal in plants, and the perception mechanism as well as downstream signaling activating the immune response are known. Here, we identify a parallel SA signaling that mediates growth attenuation. SA directly binds to A subunits of protein phosphatase 2A (PP2A), inhibiting activity of this complex. Among PP2A targets, the PIN2 auxin transporter is hyperphosphorylated in response to SA, leading to changed activity of this important growth regulator. Accordingly, auxin transport and auxin-mediated root development, including growth, gravitropic response, and lateral root organogenesis, are inhibited. This study reveals how SA, besides activating immunity, concomitantly attenuates growth through crosstalk with the auxin distribution network. Further analysis of this dual role of SA and characterization of additional SA-regulated PP2A targets will provide further insights into mechanisms maintaining a balance between growth and defense.}, author = {Tan, Shutang and Abas, Melinda F and Verstraeten, Inge and Glanc, Matous and Molnar, Gergely and Hajny, Jakub and Lasák, Pavel and Petřík, Ivan and Russinova, Eugenia and Petrášek, Jan and Novák, Ondřej and Pospíšil, Jiří and Friml, Jiří}, issn = {09609822}, journal = {Current Biology}, number = {3}, pages = {381--395.e8}, publisher = {Cell Press}, title = {{Salicylic acid targets protein phosphatase 2A to attenuate growth in plants}}, doi = {10.1016/j.cub.2019.11.058}, volume = {30}, year = {2020}, } @article{7490, abstract = {In plants, clathrin mediated endocytosis (CME) represents the major route for cargo internalisation from the cell surface. It has been assumed to operate in an evolutionary conserved manner as in yeast and animals. Here we report characterisation of ultrastructure, dynamics and mechanisms of plant CME as allowed by our advancement in electron microscopy and quantitative live imaging techniques. Arabidopsis CME appears to follow the constant curvature model and the bona fide CME population generates vesicles of a predominantly hexagonal-basket type; larger and with faster kinetics than in other models. Contrary to the existing paradigm, actin is dispensable for CME events at the plasma membrane but plays a unique role in collecting endocytic vesicles, sorting of internalised cargos and directional endosome movement that itself actively promote CME events. Internalized vesicles display a strongly delayed and sequential uncoating. These unique features highlight the independent evolution of the plant CME mechanism during the autonomous rise of multicellularity in eukaryotes.}, author = {Narasimhan, Madhumitha and Johnson, Alexander J and Prizak, Roshan and Kaufmann, Walter and Tan, Shutang and Casillas Perez, Barbara E and Friml, Jiří}, issn = {2050-084X}, journal = {eLife}, publisher = {eLife Sciences Publications}, title = {{Evolutionarily unique mechanistic framework of clathrin-mediated endocytosis in plants}}, doi = {10.7554/eLife.52067}, volume = {9}, year = {2020}, } @article{7580, abstract = {The eukaryotic endomembrane system is controlled by small GTPases of the Rab family, which are activated at defined times and locations in a switch-like manner. While this switch is well understood for an individual protein, how regulatory networks produce intracellular activity patterns is currently not known. Here, we combine in vitro reconstitution experiments with computational modeling to study a minimal Rab5 activation network. We find that the molecular interactions in this system give rise to a positive feedback and bistable collective switching of Rab5. Furthermore, we find that switching near the critical point is intrinsically stochastic and provide evidence that controlling the inactive population of Rab5 on the membrane can shape the network response. Notably, we demonstrate that collective switching can spread on the membrane surface as a traveling wave of Rab5 activation. Together, our findings reveal how biochemical signaling networks control vesicle trafficking pathways and how their nonequilibrium properties define the spatiotemporal organization of the cell.}, author = {Bezeljak, Urban and Loya, Hrushikesh and Kaczmarek, Beata M and Saunders, Timothy E. and Loose, Martin}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences}, number = {12}, pages = {6504--6549}, publisher = {Proceedings of the National Academy of Sciences}, title = {{Stochastic activation and bistability in a Rab GTPase regulatory network}}, doi = {10.1073/pnas.1921027117}, volume = {117}, year = {2020}, } @article{7600, abstract = {Directional intercellular transport of the phytohormone auxin mediated by PIN FORMED (PIN) efflux carriers plays essential roles in both coordinating patterning processes and integrating multiple external cues by rapidly redirecting auxin fluxes. Multilevel regulations of PIN activity under internal and external cues are complicated; however, the underlying molecular mechanism remains elusive. Here we demonstrate that 3’-Phosphoinositide-Dependent Protein Kinase1 (PDK1), which is conserved in plants and mammals, functions as a molecular hub integrating the upstream lipid signalling and the downstream substrate activity through phosphorylation. Genetic analysis uncovers that loss-of-function Arabidopsis mutant pdk1.1 pdk1.2 exhibits a plethora of abnormalities in organogenesis and growth, due to the defective PIN-dependent auxin transport. Further cellular and biochemical analyses reveal that PDK1 phosphorylates D6 Protein Kinase to facilitate its activity towards PIN proteins. Our studies establish a lipid-dependent phosphorylation cascade connecting membrane composition-based cellular signalling with plant growth and patterning by regulating morphogenetic auxin fluxes.}, author = {Tan, Shutang and Zhang, Xixi and Kong, Wei and Yang, Xiao-Li and Molnar, Gergely and Vondráková, Zuzana and Filepová, Roberta and Petrášek, Jan and Friml, Jiří and Xue, Hong-Wei}, issn = {20550278}, journal = {Nature Plants}, pages = {556--569}, publisher = {Springer Nature}, title = {{The lipid code-dependent phosphoswitch PDK1–D6PK activates PIN-mediated auxin efflux in Arabidopsis}}, doi = {10.1038/s41477-020-0648-9}, volume = {6}, year = {2020}, } @article{7805, abstract = {Plants as non-mobile organisms constantly integrate varying environmental signals to flexibly adapt their growth and development. Local fluctuations in water and nutrient availability, sudden changes in temperature or other abiotic and biotic stresses can trigger changes in the growth of plant organs. Multiple mutually interconnected hormonal signaling cascades act as essential endogenous translators of these exogenous signals in the adaptive responses of plants. Although the molecular backbones of hormone transduction pathways have been identified, the mechanisms underlying their interactions are largely unknown. Here, using genome wide transcriptome profiling we identify an auxin and cytokinin cross-talk component; SYNERGISTIC ON AUXIN AND CYTOKININ 1 (SYAC1), whose expression in roots is strictly dependent on both of these hormonal pathways. We show that SYAC1 is a regulator of secretory pathway, whose enhanced activity interferes with deposition of cell wall components and can fine-tune organ growth and sensitivity to soil pathogens.}, author = {Hurny, Andrej and Cuesta, Candela and Cavallari, Nicola and Ötvös, Krisztina and Duclercq, Jerome and Dokládal, Ladislav and Montesinos López, Juan C and Gallemi, Marçal and Semeradova, Hana and Rauter, Thomas and Stenzel, Irene and Persiau, Geert and Benade, Freia and Bhalearo, Rishikesh and Sýkorová, Eva and Gorzsás, András and Sechet, Julien and Mouille, Gregory and Heilmann, Ingo and De Jaeger, Geert and Ludwig-Müller, Jutta and Benková, Eva}, issn = {20411723}, journal = {Nature Communications}, publisher = {Springer Nature}, title = {{Synergistic on Auxin and Cytokinin 1 positively regulates growth and attenuates soil pathogen resistance}}, doi = {10.1038/s41467-020-15895-5}, volume = {11}, year = {2020}, } @article{7814, abstract = {Scientific research is to date largely restricted to wealthy laboratories in developed nations due to the necessity of complex and expensive equipment. This inequality limits the capacity of science to be used as a diplomatic channel. Maker movements use open-source technologies including additive manufacturing (3D printing) and laser cutting, together with low-cost computers for developing novel products. This movement is setting the groundwork for a revolution, allowing scientific equipment to be sourced at a fraction of the cost and has the potential to increase the availability of equipment for scientists around the world. Science education is increasingly recognized as another channel for science diplomacy. In this perspective, we introduce the idea that the Maker movement and open-source technologies have the potential to revolutionize science, technology, engineering and mathematics (STEM) education worldwide. We present an open-source STEM didactic tool called SCOPES (Sparking Curiosity through Open-source Platforms in Education and Science). SCOPES is self-contained, independent of local resources, and cost-effective. SCOPES can be adapted to communicate complex subjects from genetics to neurobiology, perform real-world biological experiments and explore digitized scientific samples. We envision such platforms will enhance science diplomacy by providing a means for scientists to share their findings with classrooms and for educators to incorporate didactic concepts into STEM lessons. By providing students the opportunity to design, perform, and share scientific experiments, students also experience firsthand the benefits of a multinational scientific community. We provide instructions on how to build and use SCOPES on our webpage: http://scopeseducation.org.}, author = {Beattie, Robert J and Hippenmeyer, Simon and Pauler, Florian}, issn = {2504-284X}, journal = {Frontiers in Education}, publisher = {Frontiers Media}, title = {{SCOPES: Sparking curiosity through Open-Source platforms in education and science}}, doi = {10.3389/feduc.2020.00048}, volume = {5}, year = {2020}, } @article{7815, abstract = {Beginning from a limited pool of progenitors, the mammalian cerebral cortex forms highly organized functional neural circuits. However, the underlying cellular and molecular mechanisms regulating lineage transitions of neural stem cells (NSCs) and eventual production of neurons and glia in the developing neuroepithelium remains unclear. Methods to trace NSC division patterns and map the lineage of clonally related cells have advanced dramatically. However, many contemporary lineage tracing techniques suffer from the lack of cellular resolution of progeny cell fate, which is essential for deciphering progenitor cell division patterns. Presented is a protocol using mosaic analysis with double markers (MADM) to perform in vivo clonal analysis. MADM concomitantly manipulates individual progenitor cells and visualizes precise division patterns and lineage progression at unprecedented single cell resolution. MADM-based interchromosomal recombination events during the G2-X phase of mitosis, together with temporally inducible CreERT2, provide exact information on the birth dates of clones and their division patterns. Thus, MADM lineage tracing provides unprecedented qualitative and quantitative optical readouts of the proliferation mode of stem cell progenitors at the single cell level. MADM also allows for examination of the mechanisms and functional requirements of candidate genes in NSC lineage progression. This method is unique in that comparative analysis of control and mutant subclones can be performed in the same tissue environment in vivo. Here, the protocol is described in detail, and experimental paradigms to employ MADM for clonal analysis and lineage tracing in the developing cerebral cortex are demonstrated. Importantly, this protocol can be adapted to perform MADM clonal analysis in any murine stem cell niche, as long as the CreERT2 driver is present.}, author = {Beattie, Robert J and Streicher, Carmen and Amberg, Nicole and Cheung, Giselle T and Contreras, Ximena and Hansen, Andi H and Hippenmeyer, Simon}, issn = {1940-087X}, journal = {Journal of Visual Experiments}, number = {159}, publisher = {MyJove Corporation}, title = {{Lineage tracing and clonal analysis in developing cerebral cortex using mosaic analysis with double markers (MADM)}}, doi = {10.3791/61147}, year = {2020}, } @article{7875, abstract = {Cells navigating through complex tissues face a fundamental challenge: while multiple protrusions explore different paths, the cell needs to avoid entanglement. How a cell surveys and then corrects its own shape is poorly understood. Here, we demonstrate that spatially distinct microtubule dynamics regulate amoeboid cell migration by locally promoting the retraction of protrusions. In migrating dendritic cells, local microtubule depolymerization within protrusions remote from the microtubule organizing center triggers actomyosin contractility controlled by RhoA and its exchange factor Lfc. Depletion of Lfc leads to aberrant myosin localization, thereby causing two effects that rate-limit locomotion: (1) impaired cell edge coordination during path finding and (2) defective adhesion resolution. Compromised shape control is particularly hindering in geometrically complex microenvironments, where it leads to entanglement and ultimately fragmentation of the cell body. We thus demonstrate that microtubules can act as a proprioceptive device: they sense cell shape and control actomyosin retraction to sustain cellular coherence.}, author = {Kopf, Aglaja and Renkawitz, Jörg and Hauschild, Robert and Girkontaite, Irute and Tedford, Kerry and Merrin, Jack and Thorn-Seshold, Oliver and Trauner, Dirk and Häcker, Hans and Fischer, Klaus Dieter and Kiermaier, Eva and Sixt, Michael K}, issn = {1540-8140}, journal = {The Journal of Cell Biology}, number = {6}, publisher = {Rockefeller University Press}, title = {{Microtubules control cellular shape and coherence in amoeboid migrating cells}}, doi = {10.1083/jcb.201907154}, volume = {219}, year = {2020}, } @article{7885, abstract = {Eukaryotic cells migrate by coupling the intracellular force of the actin cytoskeleton to the environment. While force coupling is usually mediated by transmembrane adhesion receptors, especially those of the integrin family, amoeboid cells such as leukocytes can migrate extremely fast despite very low adhesive forces1. Here we show that leukocytes cannot only migrate under low adhesion but can also transmit forces in the complete absence of transmembrane force coupling. When confined within three-dimensional environments, they use the topographical features of the substrate to propel themselves. Here the retrograde flow of the actin cytoskeleton follows the texture of the substrate, creating retrograde shear forces that are sufficient to drive the cell body forwards. Notably, adhesion-dependent and adhesion-independent migration are not mutually exclusive, but rather are variants of the same principle of coupling retrograde actin flow to the environment and thus can potentially operate interchangeably and simultaneously. As adhesion-free migration is independent of the chemical composition of the environment, it renders cells completely autonomous in their locomotive behaviour.}, author = {Reversat, Anne and Gärtner, Florian R and Merrin, Jack and Stopp, Julian A and Tasciyan, Saren and Aguilera Servin, Juan L and De Vries, Ingrid and Hauschild, Robert and Hons, Miroslav and Piel, Matthieu and Callan-Jones, Andrew and Voituriez, Raphael and Sixt, Michael K}, issn = {14764687}, journal = {Nature}, pages = {582–585}, publisher = {Springer Nature}, title = {{Cellular locomotion using environmental topography}}, doi = {10.1038/s41586-020-2283-z}, volume = {582}, year = {2020}, } @article{8002, abstract = {Wound healing in plant tissues, consisting of rigid cell wall-encapsulated cells, represents a considerable challenge and occurs through largely unknown mechanisms distinct from those in animals. Owing to their inability to migrate, plant cells rely on targeted cell division and expansion to regenerate wounds. Strict coordination of these wound-induced responses is essential to ensure efficient, spatially restricted wound healing. Single-cell tracking by live imaging allowed us to gain mechanistic insight into the wound perception and coordination of wound responses after laser-based wounding in Arabidopsis root. We revealed a crucial contribution of the collapse of damaged cells in wound perception and detected an auxin increase specific to cells immediately adjacent to the wound. This localized auxin increase balances wound-induced cell expansion and restorative division rates in a dose-dependent manner, leading to tumorous overproliferation when the canonical TIR1 auxin signaling is disrupted. Auxin and wound-induced turgor pressure changes together also spatially define the activation of key components of regeneration, such as the transcription regulator ERF115. Our observations suggest that the wound signaling involves the sensing of collapse of damaged cells and a local auxin signaling activation to coordinate the downstream transcriptional responses in the immediate wound vicinity.}, author = {Hörmayer, Lukas and Montesinos López, Juan C and Marhavá, Petra and Benková, Eva and Yoshida, Saiko and Friml, Jiří}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences}, number = {26}, publisher = {Proceedings of the National Academy of Sciences}, title = {{Wounding-induced changes in cellular pressure and localized auxin signalling spatially coordinate restorative divisions in roots}}, doi = {10.1073/pnas.2003346117}, volume = {117}, year = {2020}, } @misc{8097, abstract = {Antibiotics that interfere with translation, when combined, interact in diverse and difficult-to-predict ways. Here, we explain these interactions by "translation bottlenecks": points in the translation cycle where antibiotics block ribosomal progression. To elucidate the underlying mechanisms of drug interactions between translation inhibitors, we generate translation bottlenecks genetically using inducible control of translation factors that regulate well-defined translation cycle steps. These perturbations accurately mimic antibiotic action and drug interactions, supporting that the interplay of different translation bottlenecks causes these interactions. We further show that growth laws, combined with drug uptake and binding kinetics, enable the direct prediction of a large fraction of observed interactions, yet fail to predict suppression. However, varying two translation bottlenecks simultaneously supports that dense traffic of ribosomes and competition for translation factors account for the previously unexplained suppression. These results highlight the importance of "continuous epistasis" in bacterial physiology.}, author = {Kavcic, Bor}, keywords = {Escherichia coli, antibiotic combinations, translation, growth laws, drug interactions, bacterial physiology, translation inhibitors}, publisher = {Institute of Science and Technology Austria}, title = {{Analysis scripts and research data for the paper "Mechanisms of drug interactions between translation-inhibiting antibiotics"}}, doi = {10.15479/AT:ISTA:8097}, year = {2020}, } @article{8142, abstract = {Cell production and differentiation for the acquisition of specific functions are key features of living systems. The dynamic network of cellular microtubules provides the necessary platform to accommodate processes associated with the transition of cells through the individual phases of cytogenesis. Here, we show that the plant hormone cytokinin fine‐tunes the activity of the microtubular cytoskeleton during cell differentiation and counteracts microtubular rearrangements driven by the hormone auxin. The endogenous upward gradient of cytokinin activity along the longitudinal growth axis in Arabidopsis thaliana roots correlates with robust rearrangements of the microtubule cytoskeleton in epidermal cells progressing from the proliferative to the differentiation stage. Controlled increases in cytokinin activity result in premature re‐organization of the microtubule network from transversal to an oblique disposition in cells prior to their differentiation, whereas attenuated hormone perception delays cytoskeleton conversion into a configuration typical for differentiated cells. Intriguingly, cytokinin can interfere with microtubules also in animal cells, such as leukocytes, suggesting that a cytokinin‐sensitive control pathway for the microtubular cytoskeleton may be at least partially conserved between plant and animal cells.}, author = {Montesinos López, Juan C and Abuzeineh, A and Kopf, Aglaja and Juanes Garcia, Alba and Ötvös, Krisztina and Petrášek, J and Sixt, Michael K and Benková, Eva}, issn = {1460-2075}, journal = {The Embo Journal}, number = {17}, publisher = {Embo Press}, title = {{Phytohormone cytokinin guides microtubule dynamics during cell progression from proliferative to differentiated stage}}, doi = {10.15252/embj.2019104238}, volume = {39}, year = {2020}, }