Project acronym ARFMEMBRANESENSORS
Project Membrane sensors in the Arf orbit
Researcher (PI) Bruno Antonny
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Advanced Grant (AdG), LS3, ERC-2010-AdG_20100317
Summary Cellular organelles are continuously remodelled by numerous cytosolic proteins that associate transiently with their lipid membrane. Some distort the bilayer, others change its composition, extract lipids or bridge membranes at distance. Previous works from my laboratory have underlined the importance of membrane sensors, i.e. elements within proteins that help to organize membrane-remodelling events by sensing the physical and chemical state of the underlying membrane. A membrane sensor is not necessarily of well-folded domain that interacts with a specific lipid polar head: some intrinsically unfolded motifs harboring deceptively simple sequences can display remarkable membrane adhesive properties. Among these are some amphipathic helices: the ALPS motif with a polar face made mostly by small uncharged polar residues, the Spo20 helix with several histidines in its polar face and, like a mirror image of the ALPS motif, the alpha-synuclein helix with very small hydrophobic residues. Using biochemistry and molecular dynamics, we will compare the membrane binding properties of these sequences (effect of curvature, charge, lipid unsaturation); using bioinformatics we will look for new motifs, using cell biology we will assess the adaptation of these motifs to the physical and chemical features of organelle membranes. Concurrently, we will use reconstitution approaches on artificial membranes to dissect how membrane sensors contribute to the organization of vesicle tethering by golgins and sterol transport by ORP proteins. We surmise that the combination of a molecular ¿switch¿, a small G protein of the Arf family, and of membrane sensors permit to organize these complex reactions in time and in space.
Summary
Cellular organelles are continuously remodelled by numerous cytosolic proteins that associate transiently with their lipid membrane. Some distort the bilayer, others change its composition, extract lipids or bridge membranes at distance. Previous works from my laboratory have underlined the importance of membrane sensors, i.e. elements within proteins that help to organize membrane-remodelling events by sensing the physical and chemical state of the underlying membrane. A membrane sensor is not necessarily of well-folded domain that interacts with a specific lipid polar head: some intrinsically unfolded motifs harboring deceptively simple sequences can display remarkable membrane adhesive properties. Among these are some amphipathic helices: the ALPS motif with a polar face made mostly by small uncharged polar residues, the Spo20 helix with several histidines in its polar face and, like a mirror image of the ALPS motif, the alpha-synuclein helix with very small hydrophobic residues. Using biochemistry and molecular dynamics, we will compare the membrane binding properties of these sequences (effect of curvature, charge, lipid unsaturation); using bioinformatics we will look for new motifs, using cell biology we will assess the adaptation of these motifs to the physical and chemical features of organelle membranes. Concurrently, we will use reconstitution approaches on artificial membranes to dissect how membrane sensors contribute to the organization of vesicle tethering by golgins and sterol transport by ORP proteins. We surmise that the combination of a molecular ¿switch¿, a small G protein of the Arf family, and of membrane sensors permit to organize these complex reactions in time and in space.
Max ERC Funding
1 997 321 €
Duration
Start date: 2011-05-01, End date: 2015-04-30
Project acronym CAPSEVO
Project Evolution of flower morphology: the selfing syndrome in Capsella
Researcher (PI) Michael Lenhard
Host Institution (HI) UNIVERSITAET POTSDAM
Call Details Starting Grant (StG), LS3, ERC-2010-StG_20091118
Summary The change from reproduction by outbreeding to selfing is one of the most frequent evolutionary transitions in plants. This transition is generally accompanied by changes in flower morphology and function, termed the selfing syndrome, including a reduction in flower size and a more closed flower structure. While the loss of self-incompatibility is relatively well understood, little is known about the molecular basis of the associated morphological changes and their evolutionary history. We will address these problems using the species pair Capsella grandiflora (the ancestral outbreeder) and C. rubella (the derived selfing species) as a genetically tractable model. We have established recombinant inbred lines from a cross of C. grandiflora x C. rubella and mapped quantitative trait loci affecting flower size and flower opening. Using this resource, the proposal will address four objectives. (1) We will isolate causal genes underlying the variation in flower size and opening, by combining genetic mapping with next-generation sequencing. (2) We will characterize the developmental and molecular functions of the isolated genes in Capsella and Arabidopsis. (3) We will dissect the molecular basis of the different allelic effects of the causal genes to determine which kinds of mutations have led to the morphological changes. (4) Based on population-genetic analyses of the isolated genes, the evolutionary history of the morphological changes will be retraced. Together, these strands of investigation will provide a detailed understanding of general processes underlying morphological evolution in plants.
Summary
The change from reproduction by outbreeding to selfing is one of the most frequent evolutionary transitions in plants. This transition is generally accompanied by changes in flower morphology and function, termed the selfing syndrome, including a reduction in flower size and a more closed flower structure. While the loss of self-incompatibility is relatively well understood, little is known about the molecular basis of the associated morphological changes and their evolutionary history. We will address these problems using the species pair Capsella grandiflora (the ancestral outbreeder) and C. rubella (the derived selfing species) as a genetically tractable model. We have established recombinant inbred lines from a cross of C. grandiflora x C. rubella and mapped quantitative trait loci affecting flower size and flower opening. Using this resource, the proposal will address four objectives. (1) We will isolate causal genes underlying the variation in flower size and opening, by combining genetic mapping with next-generation sequencing. (2) We will characterize the developmental and molecular functions of the isolated genes in Capsella and Arabidopsis. (3) We will dissect the molecular basis of the different allelic effects of the causal genes to determine which kinds of mutations have led to the morphological changes. (4) Based on population-genetic analyses of the isolated genes, the evolutionary history of the morphological changes will be retraced. Together, these strands of investigation will provide a detailed understanding of general processes underlying morphological evolution in plants.
Max ERC Funding
1 480 826 €
Duration
Start date: 2010-12-01, End date: 2016-11-30
Project acronym CASINO
Project Carbohydrate signals controlling nodulation
Researcher (PI) Jens Stougaard Jensen
Host Institution (HI) AARHUS UNIVERSITET
Call Details Advanced Grant (AdG), LS3, ERC-2010-AdG_20100317
Summary Mechanisms governing interaction between multicellular organisms and microbes are central for understanding pathogenesis, symbiosis and the function of ecosystems. We propose to address these mechanisms by pioneering an interdisciplinary approach for understanding cellular signalling, response processes and organ development. The challenge is to determine factors synchronising three processes, organogenesis, infection thread formation and bacterial infection, running in parallel to build a root nodule hosting symbiotic bacteria. We aim to exploit the unique possibilities for analysing endocytosis of bacteria in model legumes and to develop genomic, genetic and biological chemistry tools to break new ground in our understanding of carbohydrates in plant development and plant-microbe interaction. Surface exposed rhizobial polysaccharides play a crucial but poorly understood role in infection thread formation and rhizobial invasion resulting in endocytosis. We will undertake an integrated functional characterisation of receptor-ligand mechanisms mediating recognition of secreted polysaccharides and subsequent signal amplification. So far progress in this field has been limited by the complex nature of carbohydrate polymers, lack of a suitable experimental model system where both partners in an interaction could be manipulated and lack of corresponding methods for carbohydrate synthesis, analysis and interaction studies. In this context our legume model system and the discovery that the legume Nod-factor receptors recognise bacterial lipochitin-oligosaccharide signals at their LysM domains provides a new opportunity. Combined with advanced bioorganic chemistry and nanobioscience approaches this proposal will engage the above mentioned limitations.
Summary
Mechanisms governing interaction between multicellular organisms and microbes are central for understanding pathogenesis, symbiosis and the function of ecosystems. We propose to address these mechanisms by pioneering an interdisciplinary approach for understanding cellular signalling, response processes and organ development. The challenge is to determine factors synchronising three processes, organogenesis, infection thread formation and bacterial infection, running in parallel to build a root nodule hosting symbiotic bacteria. We aim to exploit the unique possibilities for analysing endocytosis of bacteria in model legumes and to develop genomic, genetic and biological chemistry tools to break new ground in our understanding of carbohydrates in plant development and plant-microbe interaction. Surface exposed rhizobial polysaccharides play a crucial but poorly understood role in infection thread formation and rhizobial invasion resulting in endocytosis. We will undertake an integrated functional characterisation of receptor-ligand mechanisms mediating recognition of secreted polysaccharides and subsequent signal amplification. So far progress in this field has been limited by the complex nature of carbohydrate polymers, lack of a suitable experimental model system where both partners in an interaction could be manipulated and lack of corresponding methods for carbohydrate synthesis, analysis and interaction studies. In this context our legume model system and the discovery that the legume Nod-factor receptors recognise bacterial lipochitin-oligosaccharide signals at their LysM domains provides a new opportunity. Combined with advanced bioorganic chemistry and nanobioscience approaches this proposal will engage the above mentioned limitations.
Max ERC Funding
2 399 127 €
Duration
Start date: 2011-05-01, End date: 2016-04-30
Project acronym CBSCS
Project Physiology of the adult carotid body stem cell niche
Researcher (PI) Ricardo Pardal
Host Institution (HI) UNIVERSIDAD DE SEVILLA
Call Details Starting Grant (StG), LS3, ERC-2010-StG_20091118
Summary The discovery of adult neural stem cells (NSCs) has broaden our view of the physiological plasticity of the nervous system,
and has opened new perspectives on the possibility of tissue regeneration and repair in the brain. NSCs reside in specialized
niches in the adult mammalian nervous system, where they are exposed to specific paracrine signals regulating their
behavior. These neural progenitors are generally in a quiescent state within their niche, and they activate their proliferation
depending on tissue regenerative and growth needs. Understanding the mechanisms by which NSCs enter and exit the
quiescent state is crucial for the comprehension of the physiology of the adult nervous system. In this project we will study
the behavior of a specific subpopulation of adult neural stem cells recently described by our group in the carotid body (CB).
This small organ constitutes the most important chemosensor of the peripheral nervous system and has neuronal glomus
cells responsible for the chemosensing, and glia-like sustentacular cells which were thought to have just a supportive role.
We recently described that these sustentacular cells are dormant stem cells able to activate their proliferation in response to a
physiological stimulus like hypoxia, and to differentiate into new glomus cells necessary for the adaptation of the organ.
Due to our precise experimental control of the activation and deactivation of the CB neurogenic niche, we believe the CB is
an ideal model to study fundamental questions about adult neural stem cell physiology and the interaction with the niche. We
propose to study the cellular and molecular mechanisms by which these carotid body stem cells enter and exit the quiescent
state, which will help us understand the physiology of adult neurogenic niches. Likewise, understanding this neurogenic
process will improve the efficacy of using glomus cells for cell therapy against neurological disease, and might help us
understand some neural tumors.
Summary
The discovery of adult neural stem cells (NSCs) has broaden our view of the physiological plasticity of the nervous system,
and has opened new perspectives on the possibility of tissue regeneration and repair in the brain. NSCs reside in specialized
niches in the adult mammalian nervous system, where they are exposed to specific paracrine signals regulating their
behavior. These neural progenitors are generally in a quiescent state within their niche, and they activate their proliferation
depending on tissue regenerative and growth needs. Understanding the mechanisms by which NSCs enter and exit the
quiescent state is crucial for the comprehension of the physiology of the adult nervous system. In this project we will study
the behavior of a specific subpopulation of adult neural stem cells recently described by our group in the carotid body (CB).
This small organ constitutes the most important chemosensor of the peripheral nervous system and has neuronal glomus
cells responsible for the chemosensing, and glia-like sustentacular cells which were thought to have just a supportive role.
We recently described that these sustentacular cells are dormant stem cells able to activate their proliferation in response to a
physiological stimulus like hypoxia, and to differentiate into new glomus cells necessary for the adaptation of the organ.
Due to our precise experimental control of the activation and deactivation of the CB neurogenic niche, we believe the CB is
an ideal model to study fundamental questions about adult neural stem cell physiology and the interaction with the niche. We
propose to study the cellular and molecular mechanisms by which these carotid body stem cells enter and exit the quiescent
state, which will help us understand the physiology of adult neurogenic niches. Likewise, understanding this neurogenic
process will improve the efficacy of using glomus cells for cell therapy against neurological disease, and might help us
understand some neural tumors.
Max ERC Funding
1 476 000 €
Duration
Start date: 2010-11-01, End date: 2015-10-31
Project acronym CELLMIG
Project Molecular and Cellular Mechanisms Promoting Single-Cell Migration in vivo
Researcher (PI) Erez Raz
Host Institution (HI) WESTFAELISCHE WILHELMS-UNIVERSITAET MUENSTER
Call Details Advanced Grant (AdG), LS3, ERC-2010-AdG_20100317
Summary The regulation of cell migration is central in pattern formation, homeostasis and disease. The proposed research is aimed at investigating the molecular basis for cell motility and the associated polarization of the cell. In view of the dynamic nature of these processes, we have chosen to utilize the migration of Primoridal Germ Cells (PGCs) in zebrafish - a model that offers unique experimental advantages for imaging and experimental manipulations. The fact that molecules facilitating the motility of zebrafish PGCs are evolutionary conserved and the finding that the cells are directed by chemokines, molecules that control a wide range of cell trafficking events in vertebrates, make this in vivo study of particular importance.
The proposed work involves both the functional analysis of previously identified candidates and the identification of molecules, which have a presently unknown effect on the migration process. For both objectives, we will employ novel experimental schemes. We will examine the role of proteins in achieving functional cell polarity compatible with efficient motility and response to directional cues, using unique techniques and analysis tools in the context of the living organism. The precise function of the identified proteins will be determined by combining mathematical tools aimed at quantitatively gauging the role of the molecules in conferring proper cell shape, biophysical methods aimed at measuring forces, rigidity and cytoplasm flow and determination of the effect on the organization of relevant structures using cryo electron tomography.
Together, this approach would provide a non-conventional understanding of cell migration by correlating structural, morphological and dynamic cellular properties with the ability of cells to effectively migrate towards their target.
Summary
The regulation of cell migration is central in pattern formation, homeostasis and disease. The proposed research is aimed at investigating the molecular basis for cell motility and the associated polarization of the cell. In view of the dynamic nature of these processes, we have chosen to utilize the migration of Primoridal Germ Cells (PGCs) in zebrafish - a model that offers unique experimental advantages for imaging and experimental manipulations. The fact that molecules facilitating the motility of zebrafish PGCs are evolutionary conserved and the finding that the cells are directed by chemokines, molecules that control a wide range of cell trafficking events in vertebrates, make this in vivo study of particular importance.
The proposed work involves both the functional analysis of previously identified candidates and the identification of molecules, which have a presently unknown effect on the migration process. For both objectives, we will employ novel experimental schemes. We will examine the role of proteins in achieving functional cell polarity compatible with efficient motility and response to directional cues, using unique techniques and analysis tools in the context of the living organism. The precise function of the identified proteins will be determined by combining mathematical tools aimed at quantitatively gauging the role of the molecules in conferring proper cell shape, biophysical methods aimed at measuring forces, rigidity and cytoplasm flow and determination of the effect on the organization of relevant structures using cryo electron tomography.
Together, this approach would provide a non-conventional understanding of cell migration by correlating structural, morphological and dynamic cellular properties with the ability of cells to effectively migrate towards their target.
Max ERC Funding
1 960 600 €
Duration
Start date: 2011-06-01, End date: 2017-05-31
Project acronym CENTRIOLSTRUCTNUMBER
Project Control of Centriole Structure And Number
Researcher (PI) Monica Bettencourt Carvalho Dias
Host Institution (HI) FUNDACAO CALOUSTE GULBENKIAN
Call Details Starting Grant (StG), LS3, ERC-2010-StG_20091118
Summary Centrioles are essential for the formation of several microtubule organizing structures including cilia, flagella and centrosomes. These structures are involved in a variety of functions, from cell motility to division. Centrosome defects are seen in many cancers, while abnormalities in cilia and flagella can lead to a variety of human diseases, such as polycystic kidney disease. The molecular mechanisms regulating centriole biogenesis have only recently started to be unravelled, opening new ways to answer a wide range of questions that have fascinated biologists for more than a century. In this grant we are asking two fundamental questions that are central to human disease: how is centriole structure and number established and regulated in the eukaryotic cell? To address these questions we propose to identify new molecular players, and to test the role of these and known players in the context of specific mechanistic hypothesis, using in vitro and in vivo models. We propose to develop novel assays for centriole structure and regulation in order to address mechanistic problems not accessible with today s assays. In our search for novel components we will use a multidisciplinary approach combining bioinformatics with high throughput screening. The use of in vitro systems will permit the quantitative dissection of molecular mechanisms, while the study of those mechanisms in Drosophila will allow us to understand them at the whole organism level. Furthermore, this analysis, together with studies in human tissue culture cells, will allow us to understand the consequences of misregulation of these fundamental centriole properties for human disease, such as ciliopathies and cancer. My group is already collaborating with medical doctors in the study of centriole aberrations in human disease (cancer and ciliopathies), which will be invaluable to bringing the results of this study to the translational level.
Summary
Centrioles are essential for the formation of several microtubule organizing structures including cilia, flagella and centrosomes. These structures are involved in a variety of functions, from cell motility to division. Centrosome defects are seen in many cancers, while abnormalities in cilia and flagella can lead to a variety of human diseases, such as polycystic kidney disease. The molecular mechanisms regulating centriole biogenesis have only recently started to be unravelled, opening new ways to answer a wide range of questions that have fascinated biologists for more than a century. In this grant we are asking two fundamental questions that are central to human disease: how is centriole structure and number established and regulated in the eukaryotic cell? To address these questions we propose to identify new molecular players, and to test the role of these and known players in the context of specific mechanistic hypothesis, using in vitro and in vivo models. We propose to develop novel assays for centriole structure and regulation in order to address mechanistic problems not accessible with today s assays. In our search for novel components we will use a multidisciplinary approach combining bioinformatics with high throughput screening. The use of in vitro systems will permit the quantitative dissection of molecular mechanisms, while the study of those mechanisms in Drosophila will allow us to understand them at the whole organism level. Furthermore, this analysis, together with studies in human tissue culture cells, will allow us to understand the consequences of misregulation of these fundamental centriole properties for human disease, such as ciliopathies and cancer. My group is already collaborating with medical doctors in the study of centriole aberrations in human disease (cancer and ciliopathies), which will be invaluable to bringing the results of this study to the translational level.
Max ERC Funding
1 500 000 €
Duration
Start date: 2011-01-01, End date: 2016-12-31
Project acronym DOME
Project Dissecting a Novel Mechanism of Cell Motility
Researcher (PI) Tâm Mignot
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Starting Grant (StG), LS3, ERC-2010-StG_20091118
Summary Cell motility is essential for many biological processes, including development and pathogenesis. Thus, the
molecular mechanisms underlying this process have been intensively studied in many cell systems, for
example, leukocytes, amoeba and even bacteria. Intriguingly, bacteria are also able to move across solid
surfaces (gliding motility) like eukaryotic cells by a process that has remained largely mysterious. The
emergence of bacterial cell biology: the discovery that the bacterial cell also has a dynamic cytoskeleton and
specialized subcellular regions now provides new research angles to study the motility mechanism. Using
cell biology approaches, we previously suggested that the mechanism may be akin to acto-myosin-based
motility in eukaryotic cells and proposed that bacterial focal adhesion complexes also power locomotion. In
this project, we propose two complementary research axes to define both the mechanism and its spatial
regulation in the cell at molecular resolution.
Using the model motility bacterium Myxococcus xanthus, we first propose to develop a “toolbox” of
biophysical and cell biology assays to analyze the motility process. Specifically, we will construct a Traction
Force Microscopy assay designed to image the motility forces directly by live moving cells and use
microfluidics to quantitate the secretion of a mucus that may participate directly in the motility process.
These assays, combined with a newly developed laser trap system to visualize dynamic focal adhesions in
the cell envelope, will be instrumental not only to define new features of the motility process, but also to
study the function of novel motility genes which may encode the components of the elusive motility engine.
This way, we hope to establish the mechanism and structure function relationships within an entirely novel
motility machinery.
In a second part, we propose to investigate the mechanism that controls a polarity switch, allowing M.
xanthus cells to change their direction of movement. We have previously shown that dynamic motility
protein pole-to-pole oscillations convert the initial leading cell pole into the lagging pole. Here, we propose
that like in a eukaryotic cells, a bacterial counterpart of small GTPases of the Ras superfamily, MglA
controls the polarity cycle. To test this hypothesis, we will study both the MglA upstream regulation and the
MglA downstream effectors. We thus hope to establish a model of dynamic polarity control in a bacterial
Summary
Cell motility is essential for many biological processes, including development and pathogenesis. Thus, the
molecular mechanisms underlying this process have been intensively studied in many cell systems, for
example, leukocytes, amoeba and even bacteria. Intriguingly, bacteria are also able to move across solid
surfaces (gliding motility) like eukaryotic cells by a process that has remained largely mysterious. The
emergence of bacterial cell biology: the discovery that the bacterial cell also has a dynamic cytoskeleton and
specialized subcellular regions now provides new research angles to study the motility mechanism. Using
cell biology approaches, we previously suggested that the mechanism may be akin to acto-myosin-based
motility in eukaryotic cells and proposed that bacterial focal adhesion complexes also power locomotion. In
this project, we propose two complementary research axes to define both the mechanism and its spatial
regulation in the cell at molecular resolution.
Using the model motility bacterium Myxococcus xanthus, we first propose to develop a “toolbox” of
biophysical and cell biology assays to analyze the motility process. Specifically, we will construct a Traction
Force Microscopy assay designed to image the motility forces directly by live moving cells and use
microfluidics to quantitate the secretion of a mucus that may participate directly in the motility process.
These assays, combined with a newly developed laser trap system to visualize dynamic focal adhesions in
the cell envelope, will be instrumental not only to define new features of the motility process, but also to
study the function of novel motility genes which may encode the components of the elusive motility engine.
This way, we hope to establish the mechanism and structure function relationships within an entirely novel
motility machinery.
In a second part, we propose to investigate the mechanism that controls a polarity switch, allowing M.
xanthus cells to change their direction of movement. We have previously shown that dynamic motility
protein pole-to-pole oscillations convert the initial leading cell pole into the lagging pole. Here, we propose
that like in a eukaryotic cells, a bacterial counterpart of small GTPases of the Ras superfamily, MglA
controls the polarity cycle. To test this hypothesis, we will study both the MglA upstream regulation and the
MglA downstream effectors. We thus hope to establish a model of dynamic polarity control in a bacterial
Max ERC Funding
1 437 693 €
Duration
Start date: 2011-01-01, End date: 2015-12-31
Project acronym DROSOPIRNAS
Project The piRNA pathway in the Drosophila germline a small RNA based genome immune system
Researcher (PI) Julius Brennecke
Host Institution (HI) INSTITUT FUER MOLEKULARE BIOTECHNOLOGIE GMBH
Call Details Starting Grant (StG), LS3, ERC-2010-StG_20091118
Summary The discovery of RNA interference (RNAi) has revolutionized biology. As a technology it opened up new experimental and therapeutic avenues. As a biological phenomenon it changed our view on a diverse array of cellular processes. Among those are the control of gene expression, the suppression of viral replication, the formation of heterochromatin and the protection of the genome against selfish genetic elements such as transposons.
I propose to study the molecular mechanism and the biological impact of a recently discovered RNAi pathway, the Piwi interacting RNA pathway (piRNA pathway).
The piRNA pathway is an evolutionarily conserved small RNA pathway acting in the animal germline. It is the key genome surveillance system that suppresses the activity of transposons. Recent work has provided a conceptual framework for this pathway: According to this, the genome stores transposon sequences in heterochromatic loci called piRNA clusters. These provide the RNA substrates for the biogenesis of 23-29 nt long piRNAs. An amplification cycle steers piRNA production predominantly to those cluster regions that are complementary to transposons being active at a given time. Finally, piRNAs guide a protein complex centered on Piwi-proteins to complementary transposon RNAs in the cell, leading to their silencing.
In contrast to other RNAi pathways, the mechanistic framework of the piRNA pathway is largely unknown. Moreover, the spectrum of biological processes impacted by it is only poorly understood. piRNAs are for example not only derived from transposon sequences but also from various other genomic repeats that are enriched at telomeres and in heterochromatin.
We will systematically dissect the piRNA pathway regarding its molecular architecture as well as its biological functions in Drosophila. Our studies will be a combination of fly genetics, proteomics and genomics approaches. Throughout we aim at linking our results back to the underlying biology of germline development.
Summary
The discovery of RNA interference (RNAi) has revolutionized biology. As a technology it opened up new experimental and therapeutic avenues. As a biological phenomenon it changed our view on a diverse array of cellular processes. Among those are the control of gene expression, the suppression of viral replication, the formation of heterochromatin and the protection of the genome against selfish genetic elements such as transposons.
I propose to study the molecular mechanism and the biological impact of a recently discovered RNAi pathway, the Piwi interacting RNA pathway (piRNA pathway).
The piRNA pathway is an evolutionarily conserved small RNA pathway acting in the animal germline. It is the key genome surveillance system that suppresses the activity of transposons. Recent work has provided a conceptual framework for this pathway: According to this, the genome stores transposon sequences in heterochromatic loci called piRNA clusters. These provide the RNA substrates for the biogenesis of 23-29 nt long piRNAs. An amplification cycle steers piRNA production predominantly to those cluster regions that are complementary to transposons being active at a given time. Finally, piRNAs guide a protein complex centered on Piwi-proteins to complementary transposon RNAs in the cell, leading to their silencing.
In contrast to other RNAi pathways, the mechanistic framework of the piRNA pathway is largely unknown. Moreover, the spectrum of biological processes impacted by it is only poorly understood. piRNAs are for example not only derived from transposon sequences but also from various other genomic repeats that are enriched at telomeres and in heterochromatin.
We will systematically dissect the piRNA pathway regarding its molecular architecture as well as its biological functions in Drosophila. Our studies will be a combination of fly genetics, proteomics and genomics approaches. Throughout we aim at linking our results back to the underlying biology of germline development.
Max ERC Funding
1 500 000 €
Duration
Start date: 2010-09-01, End date: 2015-08-31
Project acronym DYNASTEM
Project Dynamic, stem cell-mediated self-renewal in the Drosophila intestine
Researcher (PI) Bruce Alexander Edgar
Host Institution (HI) RUPRECHT-KARLS-UNIVERSITAET HEIDELBERG
Call Details Advanced Grant (AdG), LS3, ERC-2010-AdG_20100317
Summary Cells in intestinal epithelia turn over rapidly due to aging, damage, and toxins produced by the enteric microbiota. Gut homeostasis is maintained by intestinal stem cells (ISCs) that divide to renew the intestinal epithelium, but little is known about how ISC division and differentiation are coordinated with the loss of spent gut epithelial cells. This proposal addresses the mechanisms of dynamic self-renewal in the intestine of Drosophila. Our recent work has outlined a paradigm explaining intestinal homeostasis in Drosophila that could apply also to humans. A new lab is being established in Heidelberg where we wish to extend these studies. Our objectives are to understand: 1) How intestinal stem cell pool sizes are regulated; 2) How the cytokines and growth factors that mediate gut homeostasis are controlled; and 3) How these signals regulate the ISC cell cycle. Established genetic and cell biological methods will be applied, supported by molecular assays (microarrays, qPCR, ChIP/Seq) of gene control. New pathways of ISC control will be discovered via comprehensive genetic screens using transgenic RNAi and gene over-expression. In vitro culture of ISCs will be developed and used for live imaging and molecular analysis of the mechanisms controlling ISC proliferation and differentiation. These studies should elaborate a paradigm explaining intestinal homeostasis in flies that can guide studies in mammals, eventually contributing to the diagnosis and treatment for diseases in which gut homeostasis is disrupted, such as colorectal cancer and inflammatory bowel disease. Because stem cell biology is so highly relevant to wound healing, regeneration, cancer, aging and degenerative disease, this research could impact human health at many levels.
Summary
Cells in intestinal epithelia turn over rapidly due to aging, damage, and toxins produced by the enteric microbiota. Gut homeostasis is maintained by intestinal stem cells (ISCs) that divide to renew the intestinal epithelium, but little is known about how ISC division and differentiation are coordinated with the loss of spent gut epithelial cells. This proposal addresses the mechanisms of dynamic self-renewal in the intestine of Drosophila. Our recent work has outlined a paradigm explaining intestinal homeostasis in Drosophila that could apply also to humans. A new lab is being established in Heidelberg where we wish to extend these studies. Our objectives are to understand: 1) How intestinal stem cell pool sizes are regulated; 2) How the cytokines and growth factors that mediate gut homeostasis are controlled; and 3) How these signals regulate the ISC cell cycle. Established genetic and cell biological methods will be applied, supported by molecular assays (microarrays, qPCR, ChIP/Seq) of gene control. New pathways of ISC control will be discovered via comprehensive genetic screens using transgenic RNAi and gene over-expression. In vitro culture of ISCs will be developed and used for live imaging and molecular analysis of the mechanisms controlling ISC proliferation and differentiation. These studies should elaborate a paradigm explaining intestinal homeostasis in flies that can guide studies in mammals, eventually contributing to the diagnosis and treatment for diseases in which gut homeostasis is disrupted, such as colorectal cancer and inflammatory bowel disease. Because stem cell biology is so highly relevant to wound healing, regeneration, cancer, aging and degenerative disease, this research could impact human health at many levels.
Max ERC Funding
2 682 080 €
Duration
Start date: 2011-05-01, End date: 2016-04-30
Project acronym ELEGANSFUSION
Project Mechanisms of cell fusion in eukaryotes
Researcher (PI) Benjamin Podbilewicz
Host Institution (HI) TECHNION - ISRAEL INSTITUTE OF TECHNOLOGY
Call Details Advanced Grant (AdG), LS3, ERC-2010-AdG_20100317
Summary Membrane fusion is a universal process essential inside cells (endoplasmic) and between cells in fertilization and organ formation (exoplasmic). With the exception of SNARE-mediated endoplasmic fusion the proteins that mediate cellular fusion (fusogens) are unknown. Despite many years of research, little is known about the mechanism of cell-cell fusion. Our studies of developmental cell fusion in the nematode C. elegans have led to the discovery of the first family of eukaryotic fusogens (FF). These fusogens, EFF-1 and AFF-1, are type I membrane glycoproteins that are essential for cell fusion and can fuse cells when ectopically expressed on the membranes of C. elegans and heterologous cells.
Our main goals are:
(1) To determine the physicochemical mechanism of cell membrane fusion mediated by FF proteins.
(2) To find the missing fusogens that act in cell fusion events across all kingdoms of life.
We hypothesize that FF proteins fuse membranes by a mechanism analogous to viral or endoplasmic fusogens and that unidentified fusogens fuse cells following the same principles as FF proteins.
Our specific aims are:
AIM 1 Determine the mechanism of FF-mediated cell fusion: A paradigm for cell membrane fusion
AIM 2 Find the sperm-egg fusion proteins (fusogens) in C. elegans
AIM 3 Identify the myoblast fusogens in mammals
AIM 4 Test fusogens using functional cell fusion assays in heterologous systems
Identifying critical domains required for FF fusion, intermediates in membrane remodeling, and atomic structures of FF proteins will advance the fundamental understanding of the mechanisms of eukaryotic cell fusion. We propose to find the Holy Grail of fertilization and mammalian myoblast fusion. We estimate that this project, if successful, will bring a breakthrough to the sperm-egg and muscle fusion fields with potential applications in basic and applied biomedical sciences.
Summary
Membrane fusion is a universal process essential inside cells (endoplasmic) and between cells in fertilization and organ formation (exoplasmic). With the exception of SNARE-mediated endoplasmic fusion the proteins that mediate cellular fusion (fusogens) are unknown. Despite many years of research, little is known about the mechanism of cell-cell fusion. Our studies of developmental cell fusion in the nematode C. elegans have led to the discovery of the first family of eukaryotic fusogens (FF). These fusogens, EFF-1 and AFF-1, are type I membrane glycoproteins that are essential for cell fusion and can fuse cells when ectopically expressed on the membranes of C. elegans and heterologous cells.
Our main goals are:
(1) To determine the physicochemical mechanism of cell membrane fusion mediated by FF proteins.
(2) To find the missing fusogens that act in cell fusion events across all kingdoms of life.
We hypothesize that FF proteins fuse membranes by a mechanism analogous to viral or endoplasmic fusogens and that unidentified fusogens fuse cells following the same principles as FF proteins.
Our specific aims are:
AIM 1 Determine the mechanism of FF-mediated cell fusion: A paradigm for cell membrane fusion
AIM 2 Find the sperm-egg fusion proteins (fusogens) in C. elegans
AIM 3 Identify the myoblast fusogens in mammals
AIM 4 Test fusogens using functional cell fusion assays in heterologous systems
Identifying critical domains required for FF fusion, intermediates in membrane remodeling, and atomic structures of FF proteins will advance the fundamental understanding of the mechanisms of eukaryotic cell fusion. We propose to find the Holy Grail of fertilization and mammalian myoblast fusion. We estimate that this project, if successful, will bring a breakthrough to the sperm-egg and muscle fusion fields with potential applications in basic and applied biomedical sciences.
Max ERC Funding
2 380 000 €
Duration
Start date: 2011-05-01, End date: 2016-04-30
