Project acronym Age Asymmetry
Project Age-Selective Segregation of Organelles
Researcher (PI) Pekka Aleksi Katajisto
Host Institution (HI) HELSINGIN YLIOPISTO
Call Details Starting Grant (StG), LS3, ERC-2015-STG
Summary Our tissues are constantly renewed by stem cells. Over time, stem cells accumulate cellular damage that will compromise renewal and results in aging. As stem cells can divide asymmetrically, segregation of harmful factors to the differentiating daughter cell could be one possible mechanism for slowing damage accumulation in the stem cell. However, current evidence for such mechanisms comes mainly from analogous findings in yeast, and studies have concentrated only on few types of cellular damage.
I hypothesize that the chronological age of a subcellular component is a proxy for all the damage it has sustained. In order to secure regeneration, mammalian stem cells may therefore specifically sort old cellular material asymmetrically. To study this, I have developed a novel strategy and tools to address the age-selective segregation of any protein in stem cell division. Using this approach, I have already discovered that stem-like cells of the human mammary epithelium indeed apportion chronologically old mitochondria asymmetrically in cell division, and enrich old mitochondria to the differentiating daughter cell. We will investigate the mechanisms underlying this novel phenomenon, and its relevance for mammalian aging.
We will first identify how old and young mitochondria differ, and how stem cells recognize them to facilitate the asymmetric segregation. Next, we will analyze the extent of asymmetric age-selective segregation by targeting several other subcellular compartments in a stem cell division. Finally, we will determine whether the discovered age-selective segregation is a general property of stem cell in vivo, and it's functional relevance for maintenance of stem cells and tissue regeneration. Our discoveries may open new possibilities to target aging associated functional decline by induction of asymmetric age-selective organelle segregation.
Summary
Our tissues are constantly renewed by stem cells. Over time, stem cells accumulate cellular damage that will compromise renewal and results in aging. As stem cells can divide asymmetrically, segregation of harmful factors to the differentiating daughter cell could be one possible mechanism for slowing damage accumulation in the stem cell. However, current evidence for such mechanisms comes mainly from analogous findings in yeast, and studies have concentrated only on few types of cellular damage.
I hypothesize that the chronological age of a subcellular component is a proxy for all the damage it has sustained. In order to secure regeneration, mammalian stem cells may therefore specifically sort old cellular material asymmetrically. To study this, I have developed a novel strategy and tools to address the age-selective segregation of any protein in stem cell division. Using this approach, I have already discovered that stem-like cells of the human mammary epithelium indeed apportion chronologically old mitochondria asymmetrically in cell division, and enrich old mitochondria to the differentiating daughter cell. We will investigate the mechanisms underlying this novel phenomenon, and its relevance for mammalian aging.
We will first identify how old and young mitochondria differ, and how stem cells recognize them to facilitate the asymmetric segregation. Next, we will analyze the extent of asymmetric age-selective segregation by targeting several other subcellular compartments in a stem cell division. Finally, we will determine whether the discovered age-selective segregation is a general property of stem cell in vivo, and it's functional relevance for maintenance of stem cells and tissue regeneration. Our discoveries may open new possibilities to target aging associated functional decline by induction of asymmetric age-selective organelle segregation.
Max ERC Funding
1 500 000 €
Duration
Start date: 2016-05-01, End date: 2021-04-30
Project acronym CELLFUSION
Project Molecular dissection of the mechanisms of cell-cell fusion in the fission yeast
Researcher (PI) Sophie Geneviève Elisabeth Martin Benton
Host Institution (HI) UNIVERSITE DE LAUSANNE
Call Details Consolidator Grant (CoG), LS3, ERC-2015-CoG
Summary Cell fusion is critical for fertilization and development, for instance underlying muscle or bone formation. Cell fusion may also play important roles in regeneration and cancer. A conceptual understanding is emerging that cell fusion requires cell-cell communication, polarization of the cells towards each other, and assembly of a fusion machinery, in which an actin-based structure promotes membrane juxtaposition and fusogenic factors drive membrane fusion. However, in no single system have the molecular nature of all these parts been described, and thus the molecular basis of cell fusion remains poorly understood.
This proposal aims to depict the complete fusion process in a single organism, using the simple yeast model Schizosaccharomyces pombe, which has a long track record of discoveries in fundamental cellular processes. These haploid cells, which fuse to generate a diploid zygote, use highly conserved mechanisms of cell-cell communication (through pheromones and GPCR signaling), cell polarization (centred around the small GTPase Cdc42) and fusion. Indeed, we recently showed that these cells assemble an actin-based fusion structure, dubbed the actin fusion focus. Our five aims probe the molecular nature of, and the links between, signaling, polarization and the fusion machinery from initiation to termination of the process. These are:
1: To define the roles and feedback regulation of Cdc42 during cell fusion
2: To understand the molecular mechanisms of actin fusion focus formation
3: To identify the fusogen(s) promoting membrane fusion
4: To probe the GPCR signal for fusion initiation
5: To define the mechanism of fusion termination
By combining genetic, optogenetic, biochemical, live-imaging, synthetic and modeling approaches, this project will bring a molecular and conceptual understanding of cell fusion. This work will have far-ranging relevance for cell polarization, cytoskeletal organization, cell signalling and communication, and cell fate regulation.
Summary
Cell fusion is critical for fertilization and development, for instance underlying muscle or bone formation. Cell fusion may also play important roles in regeneration and cancer. A conceptual understanding is emerging that cell fusion requires cell-cell communication, polarization of the cells towards each other, and assembly of a fusion machinery, in which an actin-based structure promotes membrane juxtaposition and fusogenic factors drive membrane fusion. However, in no single system have the molecular nature of all these parts been described, and thus the molecular basis of cell fusion remains poorly understood.
This proposal aims to depict the complete fusion process in a single organism, using the simple yeast model Schizosaccharomyces pombe, which has a long track record of discoveries in fundamental cellular processes. These haploid cells, which fuse to generate a diploid zygote, use highly conserved mechanisms of cell-cell communication (through pheromones and GPCR signaling), cell polarization (centred around the small GTPase Cdc42) and fusion. Indeed, we recently showed that these cells assemble an actin-based fusion structure, dubbed the actin fusion focus. Our five aims probe the molecular nature of, and the links between, signaling, polarization and the fusion machinery from initiation to termination of the process. These are:
1: To define the roles and feedback regulation of Cdc42 during cell fusion
2: To understand the molecular mechanisms of actin fusion focus formation
3: To identify the fusogen(s) promoting membrane fusion
4: To probe the GPCR signal for fusion initiation
5: To define the mechanism of fusion termination
By combining genetic, optogenetic, biochemical, live-imaging, synthetic and modeling approaches, this project will bring a molecular and conceptual understanding of cell fusion. This work will have far-ranging relevance for cell polarization, cytoskeletal organization, cell signalling and communication, and cell fate regulation.
Max ERC Funding
1 999 956 €
Duration
Start date: 2016-10-01, End date: 2021-09-30
Project acronym CentrioleBirthDeath
Project Mechanism of centriole inheritance and maintenance
Researcher (PI) Monica BETTENCOURT CARVALHO DIAS
Host Institution (HI) FUNDACAO CALOUSTE GULBENKIAN
Call Details Consolidator Grant (CoG), LS3, ERC-2015-CoG
Summary Centrioles assemble centrosomes and cilia/flagella, critical structures for cell division, polarity, motility and signalling, which are often deregulated in human disease. Centriole inheritance, in particular the preservation of their copy number and position in the cell is critical in many eukaryotes. I propose to investigate, in an integrative and quantitative way, how centrioles are formed in the right numbers at the right time and place, and how they are maintained to ensure their function and inheritance. We first ask how centrioles guide their own assembly position and centriole copy number. Our recent work highlighted several properties of the system, including positive and negative feedbacks and spatial cues. We explore critical hypotheses through a combination of biochemistry, quantitative live cell microscopy and computational modelling. We then ask how the centrosome and the cell cycle are both coordinated. We recently identified the triggering event in centriole biogenesis and how its regulation is akin to cell cycle control of DNA replication and centromere assembly. We will explore new hypotheses to understand how assembly time is coupled to the cell cycle. Lastly, we ask how centriole maintenance is regulated. By studying centriole disappearance in the female germline we uncovered that centrioles need to be actively maintained by their surrounding matrix. We propose to investigate how that matrix provides stability to the centrioles, whether this is differently regulated in different cell types and the possible consequences of its misregulation for the organism (infertility and ciliopathy-like symptoms). We will take advantage of several experimental systems (in silico, ex-vivo, flies and human cells), tailoring the assay to the question and allowing for comparisons across experimental systems to provide a deeper understanding of the process and its regulation.
Summary
Centrioles assemble centrosomes and cilia/flagella, critical structures for cell division, polarity, motility and signalling, which are often deregulated in human disease. Centriole inheritance, in particular the preservation of their copy number and position in the cell is critical in many eukaryotes. I propose to investigate, in an integrative and quantitative way, how centrioles are formed in the right numbers at the right time and place, and how they are maintained to ensure their function and inheritance. We first ask how centrioles guide their own assembly position and centriole copy number. Our recent work highlighted several properties of the system, including positive and negative feedbacks and spatial cues. We explore critical hypotheses through a combination of biochemistry, quantitative live cell microscopy and computational modelling. We then ask how the centrosome and the cell cycle are both coordinated. We recently identified the triggering event in centriole biogenesis and how its regulation is akin to cell cycle control of DNA replication and centromere assembly. We will explore new hypotheses to understand how assembly time is coupled to the cell cycle. Lastly, we ask how centriole maintenance is regulated. By studying centriole disappearance in the female germline we uncovered that centrioles need to be actively maintained by their surrounding matrix. We propose to investigate how that matrix provides stability to the centrioles, whether this is differently regulated in different cell types and the possible consequences of its misregulation for the organism (infertility and ciliopathy-like symptoms). We will take advantage of several experimental systems (in silico, ex-vivo, flies and human cells), tailoring the assay to the question and allowing for comparisons across experimental systems to provide a deeper understanding of the process and its regulation.
Max ERC Funding
2 000 000 €
Duration
Start date: 2017-01-01, End date: 2021-12-31
Project acronym CentSatRegFunc
Project Dissecting the function and regulation of centriolar satellites: key regulators of the centrosome/cilium complex
Researcher (PI) Elif Nur Firat Karalar
Host Institution (HI) KOC UNIVERSITY
Call Details Starting Grant (StG), LS3, ERC-2015-STG
Summary Centrosomes are the main microtubule-organizing centers of animal cells. They influence the morphology of the microtubule cytoskeleton and function as the base of primary cilium, a nexus for important signaling pathways. Structural and functional defects in centrosome/cilium complex cause a variety of human diseases including cancer, ciliopathies and microcephaly. To understand the relationship between human diseases and centrosome/cilium abnormalities, it is essential to elucidate the biogenesis of centrosome/cilium complex and the control mechanisms that regulate their structure and function. To tackle these fundamental problems, we will dissect the function and regulation of centriolar satellites, the array of granules that localize around the centrosome/cilium complex in mammalian cells. Only recently interest in the satellites has grown because mutations affecting satellite components were shown to cause ciliopathies, microcephaly and schizophrenia.
Remarkably, many centrosome/cilium proteins localize to these structures and we lack understanding of when, why and how these proteins localize to satellites. The central hypothesis of this grant is that satellites ensure proper centrosome/cilium complex structure and function by acting as transit paths for modification, assembly, storage, stability and trafficking of centrosome/cilium proteins. In Aim 1, we will identify the nature of regulatory and molecular relationship between satellites and the centrosome/cilium complex. In Aim 2, we will elucidate the role of satellites in proteostasis of centrosome/cilium proteins. In Aim 3, we will investigate the functional significance of satellite-localization of centrosome/cilium proteins during processes that go awry in human disease. Using a multidisciplinary approach, the proposed research will expand our knowledge of the spatiotemporal regulation of the centrosome/cilium complex and provide new insights into pathogenesis of ciliopathies and primary microcephaly.
Summary
Centrosomes are the main microtubule-organizing centers of animal cells. They influence the morphology of the microtubule cytoskeleton and function as the base of primary cilium, a nexus for important signaling pathways. Structural and functional defects in centrosome/cilium complex cause a variety of human diseases including cancer, ciliopathies and microcephaly. To understand the relationship between human diseases and centrosome/cilium abnormalities, it is essential to elucidate the biogenesis of centrosome/cilium complex and the control mechanisms that regulate their structure and function. To tackle these fundamental problems, we will dissect the function and regulation of centriolar satellites, the array of granules that localize around the centrosome/cilium complex in mammalian cells. Only recently interest in the satellites has grown because mutations affecting satellite components were shown to cause ciliopathies, microcephaly and schizophrenia.
Remarkably, many centrosome/cilium proteins localize to these structures and we lack understanding of when, why and how these proteins localize to satellites. The central hypothesis of this grant is that satellites ensure proper centrosome/cilium complex structure and function by acting as transit paths for modification, assembly, storage, stability and trafficking of centrosome/cilium proteins. In Aim 1, we will identify the nature of regulatory and molecular relationship between satellites and the centrosome/cilium complex. In Aim 2, we will elucidate the role of satellites in proteostasis of centrosome/cilium proteins. In Aim 3, we will investigate the functional significance of satellite-localization of centrosome/cilium proteins during processes that go awry in human disease. Using a multidisciplinary approach, the proposed research will expand our knowledge of the spatiotemporal regulation of the centrosome/cilium complex and provide new insights into pathogenesis of ciliopathies and primary microcephaly.
Max ERC Funding
1 499 819 €
Duration
Start date: 2016-06-01, End date: 2021-05-31
Project acronym CIL2015
Project Dissecting the cellular mechanics of contact inhibition of locomotion
Researcher (PI) Brian Marc Stramer
Host Institution (HI) KING'S COLLEGE LONDON
Call Details Consolidator Grant (CoG), LS3, ERC-2015-CoG
Summary Our aim is to dissect the mechanisms of contact inhibition of locomotion (CIL), a process whereby migrating cells collide and repel each other, as it is now clear that CIL is pivotal to understanding embryogenesis and pathologies such as cancer. We have developed an in vivo model using Drosophila macrophages (hemocytes), along with novel analytical tools, to examine the contact inhibition response in cells during development. We therefore have an unprecedented opportunity to address CIL in a genetically tractable organism within a physiologically relevant setting. This model has revealed that a precisely controlled CIL response is a significant driving force behind the acquisition of embryonic patterns, and recent data show that this precision requires a series of synchronized changes in cytoskeletal dynamics. Our central hypothesis is that key to this cellular ‘dance’ is mechanosensation of the collision, which integrates subsequent signaling mechanisms to choreograph the steps of the contact inhibition process. The first part of this proposal will elucidate the molecular mechanisms controlling CIL by exploiting our unique ability to live image and genetically dissect this process in Drosophila. We will also take an interdisciplinary approach to elucidate the mechanical aspects of the response, which will allow us to examine the feedback between signaling pathways and the physical forces of the CIL response. We will subsequently extend our detailed understanding of the CIL process, and our novel set of analytical tools, to mammalian cell types and model systems. This will allow us to develop new assays to directly probe the mechanics of CIL and begin to investigate the function of this underexplored process in other cell types. This in depth knowledge of the response places us in the best position to extend our understanding of CIL to new physiologically relevant scenarios that in the future will impact on human health.
Summary
Our aim is to dissect the mechanisms of contact inhibition of locomotion (CIL), a process whereby migrating cells collide and repel each other, as it is now clear that CIL is pivotal to understanding embryogenesis and pathologies such as cancer. We have developed an in vivo model using Drosophila macrophages (hemocytes), along with novel analytical tools, to examine the contact inhibition response in cells during development. We therefore have an unprecedented opportunity to address CIL in a genetically tractable organism within a physiologically relevant setting. This model has revealed that a precisely controlled CIL response is a significant driving force behind the acquisition of embryonic patterns, and recent data show that this precision requires a series of synchronized changes in cytoskeletal dynamics. Our central hypothesis is that key to this cellular ‘dance’ is mechanosensation of the collision, which integrates subsequent signaling mechanisms to choreograph the steps of the contact inhibition process. The first part of this proposal will elucidate the molecular mechanisms controlling CIL by exploiting our unique ability to live image and genetically dissect this process in Drosophila. We will also take an interdisciplinary approach to elucidate the mechanical aspects of the response, which will allow us to examine the feedback between signaling pathways and the physical forces of the CIL response. We will subsequently extend our detailed understanding of the CIL process, and our novel set of analytical tools, to mammalian cell types and model systems. This will allow us to develop new assays to directly probe the mechanics of CIL and begin to investigate the function of this underexplored process in other cell types. This in depth knowledge of the response places us in the best position to extend our understanding of CIL to new physiologically relevant scenarios that in the future will impact on human health.
Max ERC Funding
1 993 803 €
Duration
Start date: 2016-09-01, End date: 2021-08-31
Project acronym CODECHECK
Project CRACKING THE CODE BEHIND MITOTIC FIDELITY: the roles of tubulin post-translational modifications and a chromosome separation checkpoint
Researcher (PI) Helder Jose Martins Maiato
Host Institution (HI) INSTITUTO DE BIOLOGIA MOLECULAR E CELULAR-IBMC
Call Details Consolidator Grant (CoG), LS3, ERC-2015-CoG
Summary During the human lifetime 10000 trillion cell divisions take place to ensure tissue homeostasis and several vital functions in the organism. Mitosis is the process that ensures that dividing cells preserve the chromosome number of their progenitors, while deviation from this, a condition known as aneuploidy, represents the most common feature in human cancers. Here we will test two original concepts with strong implications for chromosome segregation fidelity. The first concept is based on the “tubulin code” hypothesis, which predicts that molecular motors “read” tubulin post-translational modifications on spindle microtubules. Our proof-of-concept experiments demonstrate that tubulin detyrosination works as a navigation system that guides chromosomes towards the cell equator. Thus, in addition to regulating the motors required for chromosome motion, the cell might regulate the tracks in which they move on. We will combine proteomic, super-resolution and live-cell microscopy, with in vitro reconstitutions, to perform a comprehensive survey of the tubulin code and the respective implications for motors involved in chromosome motion, mitotic spindle assembly and correction of kinetochore-microtubule attachments. The second concept is centered on the recently uncovered chromosome separation checkpoint mediated by a midzone-associated Aurora B gradient, which delays nuclear envelope reformation in response to incompletely separated chromosomes. We aim to identify Aurora B targets involved in the spatiotemporal regulation of the anaphase-telophase transition. We will establish powerful live-cell microscopy assays and a novel mammalian model system to dissect how this checkpoint allows the detection and correction of lagging/long chromosomes and DNA bridges that would otherwise contribute to genomic instability. Overall, this work will establish a paradigm shift in our understanding of how spatial information is conveyed to faithfully segregate chromosomes during mitosis.
Summary
During the human lifetime 10000 trillion cell divisions take place to ensure tissue homeostasis and several vital functions in the organism. Mitosis is the process that ensures that dividing cells preserve the chromosome number of their progenitors, while deviation from this, a condition known as aneuploidy, represents the most common feature in human cancers. Here we will test two original concepts with strong implications for chromosome segregation fidelity. The first concept is based on the “tubulin code” hypothesis, which predicts that molecular motors “read” tubulin post-translational modifications on spindle microtubules. Our proof-of-concept experiments demonstrate that tubulin detyrosination works as a navigation system that guides chromosomes towards the cell equator. Thus, in addition to regulating the motors required for chromosome motion, the cell might regulate the tracks in which they move on. We will combine proteomic, super-resolution and live-cell microscopy, with in vitro reconstitutions, to perform a comprehensive survey of the tubulin code and the respective implications for motors involved in chromosome motion, mitotic spindle assembly and correction of kinetochore-microtubule attachments. The second concept is centered on the recently uncovered chromosome separation checkpoint mediated by a midzone-associated Aurora B gradient, which delays nuclear envelope reformation in response to incompletely separated chromosomes. We aim to identify Aurora B targets involved in the spatiotemporal regulation of the anaphase-telophase transition. We will establish powerful live-cell microscopy assays and a novel mammalian model system to dissect how this checkpoint allows the detection and correction of lagging/long chromosomes and DNA bridges that would otherwise contribute to genomic instability. Overall, this work will establish a paradigm shift in our understanding of how spatial information is conveyed to faithfully segregate chromosomes during mitosis.
Max ERC Funding
2 323 468 €
Duration
Start date: 2016-07-01, End date: 2021-06-30
Project acronym COREMA
Project Cell division and the origin of embryonic aneuploidy in preimplantation mouse development
Researcher (PI) Jan ELLENBERG
Host Institution (HI) EUROPEAN MOLECULAR BIOLOGY LABORATORY
Call Details Advanced Grant (AdG), LS3, ERC-2015-AdG
Summary Cell division is fundamental for development. In the early mammalian embryo it drives the rapid proliferation of totipotent cells, the basis for forming the fetus. Given its crucial importance, it is surprising that cell division is particularly error-prone at the beginning of mammalian life, resulting in spontaneous abortion or severe developmental retardation, the incidence of which is increasing with age of the mother. Why aneuploidy is so prevalent and how early embryonic development nevertheless achieves robustness is largely unknown. The goal of this project is a comprehensive analysis of cell divisions in the mouse preimplantation embryo to determine the molecular mechanisms underlying aneuploidy and its effects on normal development. Recent technological breakthroughs, including light sheet microscopy and rapid loss-of-function approaches in the mouse embryo will allow us for the first time to tackle the molecular mechanisms of aneuploidy generation and establish the preimplantation mouse embryo as a standard cell biological model system. For that purpose we will develop next generation light sheet microscopy to enable automated chromosome tracking in the whole embryo. Mapping of cell division errors will reveal when, where, and how aneuploidy occurs, what the fate of aneuploid cells is in the embryo, and how this changes with maternal age. We will then perform high resolution functional imaging assays to identify the mitotic pathways responsible for aneuploidy and understand why they do not fully function in early development. Key proteins will be functionally characterised in detail integrating light sheet imaging with single molecule biophysics in embryos from young and aged females to achieve a mechanistic understanding of the unique aspects of cell division underlying embryonic aneuploidy. The achieved knowledge gain will have an important impact for our understanding of mammalian, including human infertility.
Summary
Cell division is fundamental for development. In the early mammalian embryo it drives the rapid proliferation of totipotent cells, the basis for forming the fetus. Given its crucial importance, it is surprising that cell division is particularly error-prone at the beginning of mammalian life, resulting in spontaneous abortion or severe developmental retardation, the incidence of which is increasing with age of the mother. Why aneuploidy is so prevalent and how early embryonic development nevertheless achieves robustness is largely unknown. The goal of this project is a comprehensive analysis of cell divisions in the mouse preimplantation embryo to determine the molecular mechanisms underlying aneuploidy and its effects on normal development. Recent technological breakthroughs, including light sheet microscopy and rapid loss-of-function approaches in the mouse embryo will allow us for the first time to tackle the molecular mechanisms of aneuploidy generation and establish the preimplantation mouse embryo as a standard cell biological model system. For that purpose we will develop next generation light sheet microscopy to enable automated chromosome tracking in the whole embryo. Mapping of cell division errors will reveal when, where, and how aneuploidy occurs, what the fate of aneuploid cells is in the embryo, and how this changes with maternal age. We will then perform high resolution functional imaging assays to identify the mitotic pathways responsible for aneuploidy and understand why they do not fully function in early development. Key proteins will be functionally characterised in detail integrating light sheet imaging with single molecule biophysics in embryos from young and aged females to achieve a mechanistic understanding of the unique aspects of cell division underlying embryonic aneuploidy. The achieved knowledge gain will have an important impact for our understanding of mammalian, including human infertility.
Max ERC Funding
2 497 156 €
Duration
Start date: 2017-01-01, End date: 2021-12-31
Project acronym DanioPattern
Project Development and Evolution of Colour Patterns in Danio species
Researcher (PI) Christiane NÜSSLEIN-VOLHARD
Host Institution (HI) MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV
Call Details Advanced Grant (AdG), LS3, ERC-2015-AdG
Summary Colour patterns are prominent features of many animals and have important functions in communication such as camouflage, kin recognition and mate selection. Colour patterns are highly variable and evolve rapidly leading to large diversities even within a single genus. As targets for natural as well as sexual selection, they are of high evolutionary significance. The zebrafish (Danio rerio), a vertebrate model organism for the study of development and disease, displays a conspicuous pattern of alternating blue and golden stripes on the body and on the anal- and tailfins. Mutants with spectacularly altered patterns have been analysed, and novel approaches in lineage tracing have provided first insights into the cellular and molecular basis of colour patterning. These studies revealed that the mechanisms at play are novel and of fundamental interest to the biology of pattern formation. Closely related Danio species have very divergent colour patterns in body and fins offering the unique opportunity to study development and evolution of colour patterns in vertebrates building on the thorough analysis of one model species. Our research in zebrafish will explore the basis of direct interactions between chromatophores mediated by channels and junctions. We will investigate the divergent mode of stripe formation in the fins and the molecular influence of the cellular environment on chromatophore interactions. In closely related Danio species, we will investigate the cellular interactions during pattern formation. We will analyse transcriptomes and genome sequences to identify candidate genes providing the molecular basis for pigment pattern diversity. These candidate genes will be tested by creating mutants and exchanging allelic variants using the CRISPR/Cas9 system. The work will lay the foundation to understand not only the genetic basis of variation in colour pattern formation between Danio species, but also the evolution of biodiversity in other vertebrates.
Summary
Colour patterns are prominent features of many animals and have important functions in communication such as camouflage, kin recognition and mate selection. Colour patterns are highly variable and evolve rapidly leading to large diversities even within a single genus. As targets for natural as well as sexual selection, they are of high evolutionary significance. The zebrafish (Danio rerio), a vertebrate model organism for the study of development and disease, displays a conspicuous pattern of alternating blue and golden stripes on the body and on the anal- and tailfins. Mutants with spectacularly altered patterns have been analysed, and novel approaches in lineage tracing have provided first insights into the cellular and molecular basis of colour patterning. These studies revealed that the mechanisms at play are novel and of fundamental interest to the biology of pattern formation. Closely related Danio species have very divergent colour patterns in body and fins offering the unique opportunity to study development and evolution of colour patterns in vertebrates building on the thorough analysis of one model species. Our research in zebrafish will explore the basis of direct interactions between chromatophores mediated by channels and junctions. We will investigate the divergent mode of stripe formation in the fins and the molecular influence of the cellular environment on chromatophore interactions. In closely related Danio species, we will investigate the cellular interactions during pattern formation. We will analyse transcriptomes and genome sequences to identify candidate genes providing the molecular basis for pigment pattern diversity. These candidate genes will be tested by creating mutants and exchanging allelic variants using the CRISPR/Cas9 system. The work will lay the foundation to understand not only the genetic basis of variation in colour pattern formation between Danio species, but also the evolution of biodiversity in other vertebrates.
Max ERC Funding
2 250 000 €
Duration
Start date: 2016-11-01, End date: 2021-04-30
Project acronym ERCOPE
Project The ER located master regulation of endosomal positioning and further movements
Researcher (PI) Jacobus (Jacques) NEEFJES
Host Institution (HI) ACADEMISCH ZIEKENHUIS LEIDEN
Call Details Advanced Grant (AdG), LS3, ERC-2015-AdG
Summary The endo-lysosomal system is critical to diverse processes, including protein homeostasis, signaling and antigen presentation. The vesicular compartment is organized as a collective unit wherein the bulk of endosomes derived from disparate origins resides in a cloud in the perinuclear region and extends outwards to include quickly moving vesicles in the periphery. At this busy intersection between the endocytic and biosynthetic pathways, lies the late endosomal compartment, responsible for protein degradation and antigen processing. In dendritic and other immune cells, this major constituent of the perinuclear cloud serves as a hub for MHC class II antigen loading. Previous work by us and others has elucidated key elements of MHC class II biology through the study of late endosomal transport to and from the cell periphery. It is clear that cell biology of endosomes is modulated by their proximity to other membrane compartments during transport, maturation, cargo selection and delivery and even during cytokinesis in cell division. However, how endosomal positioning in the perinuclear cloud and how their release for further transport is controlled remains largely unknown. The aim of this proposal is to define the molecular basis for endosomal positioning and then to interrogate the relationship between spatial regulation of the endocytic compartment and its functions with respect to i) MHC class II antigen presentation, ii) bacterial infection and iii) mitotic resolution. From a genome-wide siRNA screen for factors influencing MHC class II biology, we have identified a unique and previously uncharacterized ubiquitin ligase that resides in the ER membrane, from where it controls endosomal positioning and times their arrivals and departures as a function of its catalytic activity. On this basis, the work proposed herein is poised to resolve an entirely new molecular network in control of endosomal biology with implications for diverse biological processes.
Summary
The endo-lysosomal system is critical to diverse processes, including protein homeostasis, signaling and antigen presentation. The vesicular compartment is organized as a collective unit wherein the bulk of endosomes derived from disparate origins resides in a cloud in the perinuclear region and extends outwards to include quickly moving vesicles in the periphery. At this busy intersection between the endocytic and biosynthetic pathways, lies the late endosomal compartment, responsible for protein degradation and antigen processing. In dendritic and other immune cells, this major constituent of the perinuclear cloud serves as a hub for MHC class II antigen loading. Previous work by us and others has elucidated key elements of MHC class II biology through the study of late endosomal transport to and from the cell periphery. It is clear that cell biology of endosomes is modulated by their proximity to other membrane compartments during transport, maturation, cargo selection and delivery and even during cytokinesis in cell division. However, how endosomal positioning in the perinuclear cloud and how their release for further transport is controlled remains largely unknown. The aim of this proposal is to define the molecular basis for endosomal positioning and then to interrogate the relationship between spatial regulation of the endocytic compartment and its functions with respect to i) MHC class II antigen presentation, ii) bacterial infection and iii) mitotic resolution. From a genome-wide siRNA screen for factors influencing MHC class II biology, we have identified a unique and previously uncharacterized ubiquitin ligase that resides in the ER membrane, from where it controls endosomal positioning and times their arrivals and departures as a function of its catalytic activity. On this basis, the work proposed herein is poised to resolve an entirely new molecular network in control of endosomal biology with implications for diverse biological processes.
Max ERC Funding
2 383 625 €
Duration
Start date: 2016-09-01, End date: 2021-08-31
Project acronym GAtransport
Project A direct, multi-faceted approach to investigate plant hormones spatial regulation: the case of gibberellins
Researcher (PI) Roy Weinstain
Host Institution (HI) TEL AVIV UNIVERSITY
Call Details Starting Grant (StG), LS3, ERC-2015-STG
Summary Plants evolved a unique molecular mechanism that spatially regulate auxin, forming finely tuned gradients and local maxima of auxin that inform and direct developmental patterning and adaptive growth processes. Recent findings call into question the uniqueness of polar auxin transport in the sense that more plant hormones seem to be actively transported. Although still lacking many mechanistic details, as well as comprehensive functional connotations, these findings warrant a more thorough investigation into the prospect of a broader scope for plants spatial regulation capacity in the context of additional hormones. Critically, we lack an effective set of tools to directly investigate and dissect the particulars of plant hormones mobility at the molecular level. My long-term goal is to provide a molecular and mechanistic understanding of plant hormones dynamics that will augment our evolving model of how they are regulated and how they convey information. Here, I hypothesize that GA mobility in plants is controlled and directed by an active transport mechanism to form distinct distribution patterns that affect signaling. I will test my hypothesis with a multi-faceted and multi-disciplinary approach, combining: fluorescent labeling of key gibberellins to map their accumulation sites in whole plants and at the sub-cellular level; chemical-biology strategies that facilitate manipulation of GA “origin point” in planta to map and quantify GA flow pathways; probe-based genetic screens and un-biased photo-affinity labeling to identify proteins affecting GA mobility; and genetic and molecular biology techniques to characterize identified proteins’ functions. I expect to offer an exceptional, detailed view into the inner workings of gibberellins dynamics in planta and into the mechanisms driving it. I further anticipate that the strategies developed here to specifically address gibberellins could be straightforwardly re-tailored to investigate additional plant hormones.
Summary
Plants evolved a unique molecular mechanism that spatially regulate auxin, forming finely tuned gradients and local maxima of auxin that inform and direct developmental patterning and adaptive growth processes. Recent findings call into question the uniqueness of polar auxin transport in the sense that more plant hormones seem to be actively transported. Although still lacking many mechanistic details, as well as comprehensive functional connotations, these findings warrant a more thorough investigation into the prospect of a broader scope for plants spatial regulation capacity in the context of additional hormones. Critically, we lack an effective set of tools to directly investigate and dissect the particulars of plant hormones mobility at the molecular level. My long-term goal is to provide a molecular and mechanistic understanding of plant hormones dynamics that will augment our evolving model of how they are regulated and how they convey information. Here, I hypothesize that GA mobility in plants is controlled and directed by an active transport mechanism to form distinct distribution patterns that affect signaling. I will test my hypothesis with a multi-faceted and multi-disciplinary approach, combining: fluorescent labeling of key gibberellins to map their accumulation sites in whole plants and at the sub-cellular level; chemical-biology strategies that facilitate manipulation of GA “origin point” in planta to map and quantify GA flow pathways; probe-based genetic screens and un-biased photo-affinity labeling to identify proteins affecting GA mobility; and genetic and molecular biology techniques to characterize identified proteins’ functions. I expect to offer an exceptional, detailed view into the inner workings of gibberellins dynamics in planta and into the mechanisms driving it. I further anticipate that the strategies developed here to specifically address gibberellins could be straightforwardly re-tailored to investigate additional plant hormones.
Max ERC Funding
1 500 000 €
Duration
Start date: 2016-02-01, End date: 2021-01-31
