Project acronym ACTOMYO
Project Mechanisms of actomyosin-based contractility during cytokinesis
Researcher (PI) Ana Costa Xavier de Carvalho
Host Institution (HI) INSTITUTO DE BIOLOGIA MOLECULAR E CELULAR-IBMC
Call Details Starting Grant (StG), LS3, ERC-2014-STG
Summary Cytokinesis completes cell division by partitioning the contents of the mother cell to the two daughter cells. This process is accomplished through the assembly and constriction of a contractile ring, a complex actomyosin network that remains poorly understood on the molecular level. Research in cytokinesis has overwhelmingly focused on signaling mechanisms that dictate when and where the contractile ring is assembled. By contrast, the research I propose here addresses fundamental questions about the structural and functional properties of the contractile ring itself. We will use the nematode C. elegans to exploit the power of quantitative live imaging assays in an experimentally tractable metazoan organism. The early C. elegans embryo is uniquely suited to the study of the contractile ring, as cells dividing perpendicularly to the imaging plane provide a full end-on view of the contractile ring throughout constriction. This greatly facilitates accurate measurements of constriction kinetics, ring width and thickness, and levels as well as dynamics of fluorescently-tagged contractile ring components. Combining image-based assays with powerful molecular replacement technology for structure-function studies, we will 1) determine the contribution of branched and non-branched actin filament populations to contractile ring formation; 2) explore its ultra-structural organization in collaboration with a world expert in electron microcopy; 3) investigate how the contractile ring network is dynamically remodeled during constriction with the help of a novel laser microsurgery assay that has uncovered a remarkably robust ring repair mechanism; and 4) use a targeted RNAi screen and phenotype profiling to identify new components of actomyosin contractile networks. The results from this interdisciplinary project will significantly enhance our mechanistic understanding of cytokinesis and other cellular processes that involve actomyosin-based contractility.
Summary
Cytokinesis completes cell division by partitioning the contents of the mother cell to the two daughter cells. This process is accomplished through the assembly and constriction of a contractile ring, a complex actomyosin network that remains poorly understood on the molecular level. Research in cytokinesis has overwhelmingly focused on signaling mechanisms that dictate when and where the contractile ring is assembled. By contrast, the research I propose here addresses fundamental questions about the structural and functional properties of the contractile ring itself. We will use the nematode C. elegans to exploit the power of quantitative live imaging assays in an experimentally tractable metazoan organism. The early C. elegans embryo is uniquely suited to the study of the contractile ring, as cells dividing perpendicularly to the imaging plane provide a full end-on view of the contractile ring throughout constriction. This greatly facilitates accurate measurements of constriction kinetics, ring width and thickness, and levels as well as dynamics of fluorescently-tagged contractile ring components. Combining image-based assays with powerful molecular replacement technology for structure-function studies, we will 1) determine the contribution of branched and non-branched actin filament populations to contractile ring formation; 2) explore its ultra-structural organization in collaboration with a world expert in electron microcopy; 3) investigate how the contractile ring network is dynamically remodeled during constriction with the help of a novel laser microsurgery assay that has uncovered a remarkably robust ring repair mechanism; and 4) use a targeted RNAi screen and phenotype profiling to identify new components of actomyosin contractile networks. The results from this interdisciplinary project will significantly enhance our mechanistic understanding of cytokinesis and other cellular processes that involve actomyosin-based contractility.
Max ERC Funding
1 499 989 €
Duration
Start date: 2015-07-01, End date: 2021-06-30
Project acronym ACTOMYOSIN RING
Project Understanding Cytokinetic Actomyosin Ring Assembly Through Genetic Code Expansion, Click Chemistry, DNA origami, and in vitro Reconstitution
Researcher (PI) Mohan Balasubramanian
Host Institution (HI) THE UNIVERSITY OF WARWICK
Call Details Advanced Grant (AdG), LS3, ERC-2014-ADG
Summary The mechanism of cell division is conserved in many eukaryotes, from yeast to man. A contractile ring of filamentous actin and myosin II motors generates the force to bisect a mother cell into two daughters. The actomyosin ring is among the most complex cellular machines, comprising over 150 proteins. Understanding how these proteins organize themselves into a functional ring with appropriate contractile properties remains one of the great challenges in cell biology. Efforts to generate a comprehensive understanding of the mechanism of actomyosin ring assembly have been hampered by the lack of structural information on the arrangement of actin, myosin II, and actin modulators in the ring in its native state. Fundamental questions such as how actin filaments are assembled and organized into a ring remain actively debated. This project will investigate key issues pertaining to cytokinesis in the fission yeast Schizosaccharomyces pombe, which divides employing an actomyosin based contractile ring, using the methods of genetics, biochemistry, cellular imaging, DNA origami, genetic code expansion, and click chemistry. Specifically, we will (1) attempt to visualize actin filament assembly in live cells expressing fluorescent actin generated through synthetic biological approaches, including genetic code expansion and click chemistry (2) decipher actin filament polarity in the actomyosin ring using total internal reflection fluorescence microscopy of labelled dimeric and multimeric myosins V and VI generated through DNA origami approaches (3) address when, where, and how actin filaments for cytokinesis are assembled and organized into a ring and (4) reconstitute actin filament and functional actomyosin ring assembly in permeabilized spheroplasts and in supported bilayers. Success in the project will provide major insight into the mechanism of actomyosin ring assembly and illuminate principles behind cytoskeletal self-organization.
Summary
The mechanism of cell division is conserved in many eukaryotes, from yeast to man. A contractile ring of filamentous actin and myosin II motors generates the force to bisect a mother cell into two daughters. The actomyosin ring is among the most complex cellular machines, comprising over 150 proteins. Understanding how these proteins organize themselves into a functional ring with appropriate contractile properties remains one of the great challenges in cell biology. Efforts to generate a comprehensive understanding of the mechanism of actomyosin ring assembly have been hampered by the lack of structural information on the arrangement of actin, myosin II, and actin modulators in the ring in its native state. Fundamental questions such as how actin filaments are assembled and organized into a ring remain actively debated. This project will investigate key issues pertaining to cytokinesis in the fission yeast Schizosaccharomyces pombe, which divides employing an actomyosin based contractile ring, using the methods of genetics, biochemistry, cellular imaging, DNA origami, genetic code expansion, and click chemistry. Specifically, we will (1) attempt to visualize actin filament assembly in live cells expressing fluorescent actin generated through synthetic biological approaches, including genetic code expansion and click chemistry (2) decipher actin filament polarity in the actomyosin ring using total internal reflection fluorescence microscopy of labelled dimeric and multimeric myosins V and VI generated through DNA origami approaches (3) address when, where, and how actin filaments for cytokinesis are assembled and organized into a ring and (4) reconstitute actin filament and functional actomyosin ring assembly in permeabilized spheroplasts and in supported bilayers. Success in the project will provide major insight into the mechanism of actomyosin ring assembly and illuminate principles behind cytoskeletal self-organization.
Max ERC Funding
2 863 705 €
Duration
Start date: 2015-11-01, End date: 2020-10-31
Project acronym ArtifiCell
Project Synthetic Cell Biology: Designing organelle transport mechanisms
Researcher (PI) James Edward Rothman
Host Institution (HI) UNIVERSITY COLLEGE LONDON
Call Details Advanced Grant (AdG), LS3, ERC-2014-ADG
Summary Imagine being able to design into living cells and organisms de novo vesicle transport mechanisms that do not naturally exist? At one level this is a wild-eyed notion of synthetic biology.
But we contend that this vision can be approached even today, focusing first on the process of exocytosis, a fundamental process that impacts almost every area of physiology. Enough has now been learned about the natural core machinery (as recognized by the award of the 2013 Nobel Prize in Physiology or Medicine to the PI and others) to take highly innovative physics/engineering- and DNA-based approaches to design synthetic versions of the secretory apparatus that could someday open new avenues in genetic medicine.
The central idea is to introduce DNA-based functional equivalents of the core protein machinery that naturally form (coats), target (tethers), and fuse (SNAREs) vesicles. We have already taken first steps by using DNA origami-based templates to produce synthetic phospholipid vesicles and complementary DNA-based tethers to specifically capture these DNA-templated vesicles on targeted bilayers. Others have linked DNA oligonucleotides to trigger vesicle fusion.
The next and much more challenging step is to introduce such processes into living cells. We hope to break this barrier, and in the process start a new field of research into “synthetic exocytosis”, by introducing Peptide-Nucleic Acids (PNAs) of tethers and SNAREs to re-direct naturally-produced secretory vesicles to artificially-programmed targets and provide artificially-programmed regulation. PNAs are chosen mainly because they lack the negatively charged phosphate backbones of DNA, and therefore are more readily delivered into the cell across the plasma membrane. Future steps, would include producing the transport vesicles synthetically within the cell by externally supplied origami-based PNA or similar cages, and - much more speculatively - ultimately using encoded DNA and RNAs to provide these functions.
Summary
Imagine being able to design into living cells and organisms de novo vesicle transport mechanisms that do not naturally exist? At one level this is a wild-eyed notion of synthetic biology.
But we contend that this vision can be approached even today, focusing first on the process of exocytosis, a fundamental process that impacts almost every area of physiology. Enough has now been learned about the natural core machinery (as recognized by the award of the 2013 Nobel Prize in Physiology or Medicine to the PI and others) to take highly innovative physics/engineering- and DNA-based approaches to design synthetic versions of the secretory apparatus that could someday open new avenues in genetic medicine.
The central idea is to introduce DNA-based functional equivalents of the core protein machinery that naturally form (coats), target (tethers), and fuse (SNAREs) vesicles. We have already taken first steps by using DNA origami-based templates to produce synthetic phospholipid vesicles and complementary DNA-based tethers to specifically capture these DNA-templated vesicles on targeted bilayers. Others have linked DNA oligonucleotides to trigger vesicle fusion.
The next and much more challenging step is to introduce such processes into living cells. We hope to break this barrier, and in the process start a new field of research into “synthetic exocytosis”, by introducing Peptide-Nucleic Acids (PNAs) of tethers and SNAREs to re-direct naturally-produced secretory vesicles to artificially-programmed targets and provide artificially-programmed regulation. PNAs are chosen mainly because they lack the negatively charged phosphate backbones of DNA, and therefore are more readily delivered into the cell across the plasma membrane. Future steps, would include producing the transport vesicles synthetically within the cell by externally supplied origami-based PNA or similar cages, and - much more speculatively - ultimately using encoded DNA and RNAs to provide these functions.
Max ERC Funding
3 000 000 €
Duration
Start date: 2015-09-01, End date: 2021-08-31
Project acronym AutoRecon
Project Molecular mechanisms of autophagosome formation during selective autophagy
Researcher (PI) Sascha Martens
Host Institution (HI) UNIVERSITAT WIEN
Call Details Consolidator Grant (CoG), LS3, ERC-2014-CoG
Summary I propose to study how eukaryotic cells generate autophagosomes, organelles bounded by a double membrane. These are formed during autophagy and mediate the degradation of cytoplasmic substances within the lysosomal compartment. Autophagy thereby protects the organism from pathological conditions such as neurodegeneration, cancer and infections. Many core factors required for autophagosome formation have been identified but the order in which they act and their mode of action is still unclear. We will use a combination of biochemical and cell biological approaches to elucidate the choreography and mechanism of these core factors. In particular, we will focus on selective autophagy and determine how the autophagic machinery generates an autophagosome that selectively contains the cargo.
To this end we will focus on the cytoplasm-to-vacuole-targeting pathway in S. cerevisiae that mediates the constitutive delivery of the prApe1 enzyme into the vacuole. We will use cargo mimetics or prApe1 complexes in combination with purified autophagy proteins and vesicles to reconstitute the process and so determine which factors are both necessary and sufficient for autophagosome formation, as well as elucidating their mechanism of action.
In parallel we will study selective autophagosome formation in human cells. This will reveal common principles and special adaptations. In particular, we will use cell lysates from genome-edited cells in combination with purified autophagy proteins to reconstitute selective autophagosome formation around ubiquitin-positive cargo material. The insights and hypotheses obtained from these reconstituted systems will be validated using cell biological approaches.
Taken together, our experiments will allow us to delineate the major steps of autophagosome formation during selective autophagy. Our results will yield detailed insights into how cells form and shape organelles in a de novo manner, which is major question in cell- and developmental biology.
Summary
I propose to study how eukaryotic cells generate autophagosomes, organelles bounded by a double membrane. These are formed during autophagy and mediate the degradation of cytoplasmic substances within the lysosomal compartment. Autophagy thereby protects the organism from pathological conditions such as neurodegeneration, cancer and infections. Many core factors required for autophagosome formation have been identified but the order in which they act and their mode of action is still unclear. We will use a combination of biochemical and cell biological approaches to elucidate the choreography and mechanism of these core factors. In particular, we will focus on selective autophagy and determine how the autophagic machinery generates an autophagosome that selectively contains the cargo.
To this end we will focus on the cytoplasm-to-vacuole-targeting pathway in S. cerevisiae that mediates the constitutive delivery of the prApe1 enzyme into the vacuole. We will use cargo mimetics or prApe1 complexes in combination with purified autophagy proteins and vesicles to reconstitute the process and so determine which factors are both necessary and sufficient for autophagosome formation, as well as elucidating their mechanism of action.
In parallel we will study selective autophagosome formation in human cells. This will reveal common principles and special adaptations. In particular, we will use cell lysates from genome-edited cells in combination with purified autophagy proteins to reconstitute selective autophagosome formation around ubiquitin-positive cargo material. The insights and hypotheses obtained from these reconstituted systems will be validated using cell biological approaches.
Taken together, our experiments will allow us to delineate the major steps of autophagosome formation during selective autophagy. Our results will yield detailed insights into how cells form and shape organelles in a de novo manner, which is major question in cell- and developmental biology.
Max ERC Funding
1 999 640 €
Duration
Start date: 2016-03-01, End date: 2021-02-28
Project acronym AuxinER
Project Mechanisms of Auxin-dependent Signaling in the Endoplasmic Reticulum
Researcher (PI) Jürgen Kleine-Vehn
Host Institution (HI) UNIVERSITAET FUER BODENKULTUR WIEN
Call Details Starting Grant (StG), LS3, ERC-2014-STG
Summary The phytohormone auxin has profound importance for plant development. The extracellular AUXIN BINDING PROTEIN1 (ABP1) and the nuclear AUXIN F-BOX PROTEINs (TIR1/AFBs) auxin receptors perceive fast, non-genomic and slow, genomic auxin responses, respectively. Despite the fact that ABP1 mainly localizes to the endoplasmic reticulum (ER), until now it has been proposed to be active only in the extracellular matrix (reviewed in Sauer and Kleine-Vehn, 2011). Just recently, ABP1 function was also linked to genomic responses, modulating TIR1/AFB-dependent processes (Tromas et al., 2013). Intriguingly, the genomic effect of ABP1 appears to be at least partially independent of the endogenous auxin indole 3-acetic acid (IAA) (Paque et al., 2014).
In this proposal my main research objective is to unravel the importance of the ER for genomic auxin responses. The PIN-LIKES (PILS) putative carriers for auxinic compounds also localize to the ER and determine the cellular sensitivity to auxin. PILS5 gain-of-function reduces canonical auxin signaling (Barbez et al., 2012) and phenocopies abp1 knock down lines (Barbez et al., 2012, Paque et al., 2014). Accordingly, a PILS-dependent substrate could be a negative regulator of ABP1 function in the ER. Based on our unpublished data, an IAA metabolite could play a role in ABP1-dependent processes in the ER, possibly providing feedback on the canonical nuclear IAA-signaling.
I hypothesize that the genomic auxin response may be an integration of auxin- and auxin-metabolite-dependent nuclear and ER localized signaling, respectively. This proposed project aims to characterize a novel auxin-signaling paradigm in plants. We will employ state of the art interdisciplinary (biochemical, biophysical, computational modeling, molecular, and genetic) methods to assess the projected research. The identification of the proposed auxin conjugate-dependent signal could have far reaching plant developmental and biotechnological importance.
Summary
The phytohormone auxin has profound importance for plant development. The extracellular AUXIN BINDING PROTEIN1 (ABP1) and the nuclear AUXIN F-BOX PROTEINs (TIR1/AFBs) auxin receptors perceive fast, non-genomic and slow, genomic auxin responses, respectively. Despite the fact that ABP1 mainly localizes to the endoplasmic reticulum (ER), until now it has been proposed to be active only in the extracellular matrix (reviewed in Sauer and Kleine-Vehn, 2011). Just recently, ABP1 function was also linked to genomic responses, modulating TIR1/AFB-dependent processes (Tromas et al., 2013). Intriguingly, the genomic effect of ABP1 appears to be at least partially independent of the endogenous auxin indole 3-acetic acid (IAA) (Paque et al., 2014).
In this proposal my main research objective is to unravel the importance of the ER for genomic auxin responses. The PIN-LIKES (PILS) putative carriers for auxinic compounds also localize to the ER and determine the cellular sensitivity to auxin. PILS5 gain-of-function reduces canonical auxin signaling (Barbez et al., 2012) and phenocopies abp1 knock down lines (Barbez et al., 2012, Paque et al., 2014). Accordingly, a PILS-dependent substrate could be a negative regulator of ABP1 function in the ER. Based on our unpublished data, an IAA metabolite could play a role in ABP1-dependent processes in the ER, possibly providing feedback on the canonical nuclear IAA-signaling.
I hypothesize that the genomic auxin response may be an integration of auxin- and auxin-metabolite-dependent nuclear and ER localized signaling, respectively. This proposed project aims to characterize a novel auxin-signaling paradigm in plants. We will employ state of the art interdisciplinary (biochemical, biophysical, computational modeling, molecular, and genetic) methods to assess the projected research. The identification of the proposed auxin conjugate-dependent signal could have far reaching plant developmental and biotechnological importance.
Max ERC Funding
1 441 125 €
Duration
Start date: 2015-06-01, End date: 2020-11-30
Project acronym bi-BLOCK
Project Building and bypassing plant polyspermy blocks
Researcher (PI) Rita Helene Groß-Hardt
Host Institution (HI) UNIVERSITAET BREMEN
Call Details Consolidator Grant (CoG), LS3, ERC-2014-CoG
Summary The ultimate goal for the survival of all species on earth is to reproduce. This uncompromising principle has triggered the evolution of numerous adaptations. One strategy commonly employed by sexually reproducing eukaryotes is the production of tremendous amounts of sperm to maximize the likelihood of an egg becoming fertilised. High sperm to egg ratios are, however, associated with an increased risk of supernumerary sperm fusion. This so-called polyspermy is lethal in many organisms. Accordingly, eukaryotes have evolved polyspermy barriers, which are implemented at different levels in the reproductive process. Flowering plants tightly control the number of sperm-transporting pollen tubes approaching a single ovule by a so-called pollen tube block. We have recently shown that the pollen tube block is relaxed in ethylene hyposensitive plants. Capitalizing on these results, this project aims at identifying and characterising the molecular mechanisms underlying plant polyspermy barriers.
Summary
The ultimate goal for the survival of all species on earth is to reproduce. This uncompromising principle has triggered the evolution of numerous adaptations. One strategy commonly employed by sexually reproducing eukaryotes is the production of tremendous amounts of sperm to maximize the likelihood of an egg becoming fertilised. High sperm to egg ratios are, however, associated with an increased risk of supernumerary sperm fusion. This so-called polyspermy is lethal in many organisms. Accordingly, eukaryotes have evolved polyspermy barriers, which are implemented at different levels in the reproductive process. Flowering plants tightly control the number of sperm-transporting pollen tubes approaching a single ovule by a so-called pollen tube block. We have recently shown that the pollen tube block is relaxed in ethylene hyposensitive plants. Capitalizing on these results, this project aims at identifying and characterising the molecular mechanisms underlying plant polyspermy barriers.
Max ERC Funding
1 910 769 €
Duration
Start date: 2015-09-01, End date: 2021-03-31
Project acronym ChromoCellDev
Project Chromosome Architecture and the Fidelity of Mitosis during Development
Researcher (PI) Raquel Aguiar Cardoso de Oliveira
Host Institution (HI) FUNDACAO CALOUSTE GULBENKIAN
Call Details Starting Grant (StG), LS3, ERC-2014-STG
Summary Genome stability relies on accurate partition of the genome during nuclear division. Proper mitosis, in turn, depends on changes in chromosome organization, such as chromosome condensation and sister chromatid cohesion. Despite the importance of these structural changes, chromatin itself has been long assumed to play a rather passive role during mitosis and chromosomes are usually compared to a “corpse at a funeral: they provide the reason for the proceedings but do not take an active part in them.” (Mazia, 1961). Recent evidence, however, suggests that chromosomes play a more active role in the process of their own segregation. The present proposal tests the “active chromosome” hypothesis by investigating how chromosome morphology influences the fidelity of mitosis. I will use innovative methods for acute protein inactivation, developed during my postdoctoral studies, to evaluate the role of two key protein complexes involved in mitotic chromosome architecture - Condensins and Cohesins. Using a multidisciplinary approach, combining acute protein inactivation, 3D-live cell imaging and quantitative methods, I propose to investigate the role of mitotic chromosomes in the fidelity of mitosis at three different levels. The first one will use novel approaches to uncover the process of mitotic chromosome assembly, which is still largely unknown. The second will explore how mitotic chromosomes take an active part in mitosis by examining how chromosome condensation and cohesion influence chromosome movement and the signalling of the surveillance mechanisms that control nuclear division. Lastly we will evaluate how mitotic errors arising from abnormal chromosome structure impact on development. We aim to evaluate, at the cellular and organism level, how the cell perceives such errors and how (indeed if) they tolerate mitotic abnormalities. By conceptually challenging the passive chromosome view this project has the potential to redefine the role of chromatin during mitosis.
Summary
Genome stability relies on accurate partition of the genome during nuclear division. Proper mitosis, in turn, depends on changes in chromosome organization, such as chromosome condensation and sister chromatid cohesion. Despite the importance of these structural changes, chromatin itself has been long assumed to play a rather passive role during mitosis and chromosomes are usually compared to a “corpse at a funeral: they provide the reason for the proceedings but do not take an active part in them.” (Mazia, 1961). Recent evidence, however, suggests that chromosomes play a more active role in the process of their own segregation. The present proposal tests the “active chromosome” hypothesis by investigating how chromosome morphology influences the fidelity of mitosis. I will use innovative methods for acute protein inactivation, developed during my postdoctoral studies, to evaluate the role of two key protein complexes involved in mitotic chromosome architecture - Condensins and Cohesins. Using a multidisciplinary approach, combining acute protein inactivation, 3D-live cell imaging and quantitative methods, I propose to investigate the role of mitotic chromosomes in the fidelity of mitosis at three different levels. The first one will use novel approaches to uncover the process of mitotic chromosome assembly, which is still largely unknown. The second will explore how mitotic chromosomes take an active part in mitosis by examining how chromosome condensation and cohesion influence chromosome movement and the signalling of the surveillance mechanisms that control nuclear division. Lastly we will evaluate how mitotic errors arising from abnormal chromosome structure impact on development. We aim to evaluate, at the cellular and organism level, how the cell perceives such errors and how (indeed if) they tolerate mitotic abnormalities. By conceptually challenging the passive chromosome view this project has the potential to redefine the role of chromatin during mitosis.
Max ERC Funding
1 492 000 €
Duration
Start date: 2015-10-01, End date: 2021-09-30
Project acronym COLOUR PATTERN
Project Morphogenesis and Molecular Regulation of Colour Patterning in Birds
Researcher (PI) Marie Celine Manceau
Host Institution (HI) COLLEGE DE FRANCE
Call Details Starting Grant (StG), LS3, ERC-2014-STG
Summary Animals display a tremendous diversity of patterns ‒from the colourful designs that adorn their body to repeated segmented appendages. Natural patterns result from the formation of discrete domains within developing tissues through the integration of positional cues by cells that consequently adopt specific fates and produce spatial heterogeneity. How can such developmental processes underlie the apparent complexity and diversity of natural patterns? We propose to address this long-standing question with an innovative experimental design: we will make use of natural variation as a powerful tool to facilitate the identification of patterning molecules and morphogenetic events. We will study colour pattern, a crucial adaptive trait that varies extensively in nature, from large colour domains to periodic designs. In amniotes, colour pattern is formed by spatial differences in the distribution of pigment cells and integumentary appendages. While the pigmentation system has been well characterized, the mechanisms governing the formation of compartments in the skin of wild animals have remained unclear, largely because laboratory models do not display ecologically-relevant colour patterns. We will use a combination of forward genetics, developmental biology, modelling, and imaging to study natural variation in the large colour domains of Estrildid finches and the periodic stripes of Galliform birds. For both phenotypes, we will characterize the organization of the embryonic skin and the mode of patterning (i.e., instructional patterning via external cues vs locally-occurring self-organization) underlying their formation, and identify the molecular factors and developmental processes contributing to their variation. Results from these studies will elucidate the biochemical events and tissue rearrangements orchestrating colour patterning in development and shed light on how these processes shape natural variation in this trait‒ and more generally, in natural patterns.
Summary
Animals display a tremendous diversity of patterns ‒from the colourful designs that adorn their body to repeated segmented appendages. Natural patterns result from the formation of discrete domains within developing tissues through the integration of positional cues by cells that consequently adopt specific fates and produce spatial heterogeneity. How can such developmental processes underlie the apparent complexity and diversity of natural patterns? We propose to address this long-standing question with an innovative experimental design: we will make use of natural variation as a powerful tool to facilitate the identification of patterning molecules and morphogenetic events. We will study colour pattern, a crucial adaptive trait that varies extensively in nature, from large colour domains to periodic designs. In amniotes, colour pattern is formed by spatial differences in the distribution of pigment cells and integumentary appendages. While the pigmentation system has been well characterized, the mechanisms governing the formation of compartments in the skin of wild animals have remained unclear, largely because laboratory models do not display ecologically-relevant colour patterns. We will use a combination of forward genetics, developmental biology, modelling, and imaging to study natural variation in the large colour domains of Estrildid finches and the periodic stripes of Galliform birds. For both phenotypes, we will characterize the organization of the embryonic skin and the mode of patterning (i.e., instructional patterning via external cues vs locally-occurring self-organization) underlying their formation, and identify the molecular factors and developmental processes contributing to their variation. Results from these studies will elucidate the biochemical events and tissue rearrangements orchestrating colour patterning in development and shed light on how these processes shape natural variation in this trait‒ and more generally, in natural patterns.
Max ERC Funding
1 483 144 €
Duration
Start date: 2015-05-01, End date: 2020-04-30
Project acronym EPAF
Project Role of Epithelial Apoptotic Force in Morphogenesis
Researcher (PI) Magali Aude Emmanuelle SUZANNE
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Consolidator Grant (CoG), LS3, ERC-2014-CoG
Summary Contrary to previous beliefs, recent studies have suggested that apoptotic cells play an important dynamic role during morphogenesis. Nonetheless, the mechanisms whereby dying cells drive tissue shape modification remain elusive.
Using the Drosophila developing leg as a model system to study apoptosis-dependent epithelium folding, we have recently shown that apoptotic cells produce a pulling force through the unexpected maintenance of their adherens junctions that serves as an anchor to an apico-basal Myosin II cable. The resulting apoptotic apico-basal force leads to a non-autonomous increase in tissue tension and apical constriction of surrounding cells, leading to epithelium folding. These results reveal that, far from being passively eliminated as generally thought, dying cells are very active until the end of the apoptotic process. The objective of the present proposal is to understand how apoptotic cells influence their surroundings from the micro-environment to the macro-scale level.
Our first aim is to dissect the cellular mechanisms governing the generation of the apoptotic force and its transmission to the tissue, both apically through planar polarity and basally through the extra-cellular matrix (ECM), in parallel with the identification of the network of genes orchestrating apoptosis-dependent morphogenesis through a powerful genetic screen. Interesting preliminary results have already identified the epithelio-mesenchymal-transition gene Snail as essential for the progression of apoptosis, thus validating our approach.
Therefore, the second aim of this project is to compare Snail function in the control of adhesion and ECM dynamics and in the generation of tissue tension in both EMT and apoptosis. This original comparative study should bring novel insight into these two fundamental processes.
To perform this work, we will use elegant genetic tools combined to state-of-the-art live imaging techniques, together with robust biophysical modelling.
Summary
Contrary to previous beliefs, recent studies have suggested that apoptotic cells play an important dynamic role during morphogenesis. Nonetheless, the mechanisms whereby dying cells drive tissue shape modification remain elusive.
Using the Drosophila developing leg as a model system to study apoptosis-dependent epithelium folding, we have recently shown that apoptotic cells produce a pulling force through the unexpected maintenance of their adherens junctions that serves as an anchor to an apico-basal Myosin II cable. The resulting apoptotic apico-basal force leads to a non-autonomous increase in tissue tension and apical constriction of surrounding cells, leading to epithelium folding. These results reveal that, far from being passively eliminated as generally thought, dying cells are very active until the end of the apoptotic process. The objective of the present proposal is to understand how apoptotic cells influence their surroundings from the micro-environment to the macro-scale level.
Our first aim is to dissect the cellular mechanisms governing the generation of the apoptotic force and its transmission to the tissue, both apically through planar polarity and basally through the extra-cellular matrix (ECM), in parallel with the identification of the network of genes orchestrating apoptosis-dependent morphogenesis through a powerful genetic screen. Interesting preliminary results have already identified the epithelio-mesenchymal-transition gene Snail as essential for the progression of apoptosis, thus validating our approach.
Therefore, the second aim of this project is to compare Snail function in the control of adhesion and ECM dynamics and in the generation of tissue tension in both EMT and apoptosis. This original comparative study should bring novel insight into these two fundamental processes.
To perform this work, we will use elegant genetic tools combined to state-of-the-art live imaging techniques, together with robust biophysical modelling.
Max ERC Funding
2 311 844 €
Duration
Start date: 2015-09-01, End date: 2020-08-31
Project acronym EPIROSE
Project Self-Organising Capacity of Stem Cells during Implantation and Early Post-implantation Development: Implications for Human Development
Researcher (PI) Magdalena Zernicka-goetz
Host Institution (HI) THE CHANCELLOR MASTERS AND SCHOLARSOF THE UNIVERSITY OF CAMBRIDGE
Call Details Advanced Grant (AdG), LS3, ERC-2014-ADG
Summary Embryonic development progresses through successive cell fate decisions and intricate three-dimensional morphogenetic transformations. Implantation is the defining event in mammalian pregnancy during which a fundamental morphogenetic transformation is initiated: the body axes are established and the embryonic germ layers created. Despite its importance, a comprehensive understanding of the molecular mechanisms, transcriptional pathways, cellular interactions, as well as the spatio-temporal development of the embryo at implantation stages is at present lacking, due to the embryo’s inaccessibility. To overcome these limitations, we generated a culture system that allows the development of mouse implanting embryos outside of the mother. This system provides the opportunity to address how architectural features and signaling events integrate to induce the emergence of the body plan. Combining this new technology with the analysis of genetically engineered mouse embryos, the aim of this research proposal is to fill the knowledge gap between pre and post-implantation development. Single cell sequencing, two-photon microscopy, high-content forward genetic screening, and modeling will be merged with a functional assessment of embryo development in vivo to reveal the determinants of implantation and early post-implantation development. This global understanding will be employed to explore the extent to which stem cells can recapitulate embryonic development, with tremendous potential for regenerative medicine. Knowledge of the cellular and molecular mechanisms that intertwine lineage specification, developmental potential, and tissue morphogenesis will offer novel insight on the pathological causes of embryo lethality and congenital disorders. The proposed studies will shed light on this crucial yet mysterious stage of development in the mouse and, by extrapolation, offer outstanding potential to advance our understanding of human development.
Summary
Embryonic development progresses through successive cell fate decisions and intricate three-dimensional morphogenetic transformations. Implantation is the defining event in mammalian pregnancy during which a fundamental morphogenetic transformation is initiated: the body axes are established and the embryonic germ layers created. Despite its importance, a comprehensive understanding of the molecular mechanisms, transcriptional pathways, cellular interactions, as well as the spatio-temporal development of the embryo at implantation stages is at present lacking, due to the embryo’s inaccessibility. To overcome these limitations, we generated a culture system that allows the development of mouse implanting embryos outside of the mother. This system provides the opportunity to address how architectural features and signaling events integrate to induce the emergence of the body plan. Combining this new technology with the analysis of genetically engineered mouse embryos, the aim of this research proposal is to fill the knowledge gap between pre and post-implantation development. Single cell sequencing, two-photon microscopy, high-content forward genetic screening, and modeling will be merged with a functional assessment of embryo development in vivo to reveal the determinants of implantation and early post-implantation development. This global understanding will be employed to explore the extent to which stem cells can recapitulate embryonic development, with tremendous potential for regenerative medicine. Knowledge of the cellular and molecular mechanisms that intertwine lineage specification, developmental potential, and tissue morphogenesis will offer novel insight on the pathological causes of embryo lethality and congenital disorders. The proposed studies will shed light on this crucial yet mysterious stage of development in the mouse and, by extrapolation, offer outstanding potential to advance our understanding of human development.
Max ERC Funding
2 477 951 €
Duration
Start date: 2016-01-01, End date: 2021-12-31
