Project acronym 3D-loop
Project Mechanism of homology search and the logic of homologous chromosome pairing in meiosis
Researcher (PI) Aurele PIAZZA
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Starting Grant (StG), LS2, ERC-2019-STG
Summary Homologous recombination (HR) is a conserved DNA double-strand breaks (DSB) repair pathway that uniquely uses an intact DNA molecule as a template. Genome-wide homology search is carried out by a nucleoprotein filament (NPF) assembled on the ssDNA flanking the DSB, and whose product is a “D-loop” joint molecule. Beyond accurate DSB repair, this capacity of HR to spatially associates homologous molecules is also harnessed for homolog pairing in meiosis. The goal of “3D-loop” is to tackle two long lasting conundrums: the fundamental homology search mechanism that achieves accurate and efficient identification of a single homologous donor in the vastness of the genome and nucleus, and how this mechanism is adapted for the purpose of homologs attachment in meiosis.
I overcame the main hurdle to study these core steps of HR by developing a suite of proximity ligation-based methodologies and experimental systems to physically detect joint molecules in yeast cells. It revealed elaborate regulation controlling D-loop dynamics and a novel class of joint molecules. This proposal builds upon these methodologies and findings to first address basic properties of the homology sampling process by the NPF and the role of D-loop dynamics, with the long-term goal to establish a quantitative framework of homology search in mitotic cells (WP1). Second, the meiosis-specific regulation of homology search leading to homolog pairing likely integrates chromosomal-scale information. Genome re-synthesis and engineering approaches will be deployed to (i) achieve a quantitative and dynamic cartography of the cytological and molecular events of meiosis over a large chromosomal region, (ii) probe cis-acting regulations at the chromosomal scale, and (iii) revisit the molecular paradigm for crossover formation (WP2). We expect this project to shed light on the fundamental process of homology search and its involvement in the chromosome pairing phenomenon lying at the basis of sexual reproduction.
Summary
Homologous recombination (HR) is a conserved DNA double-strand breaks (DSB) repair pathway that uniquely uses an intact DNA molecule as a template. Genome-wide homology search is carried out by a nucleoprotein filament (NPF) assembled on the ssDNA flanking the DSB, and whose product is a “D-loop” joint molecule. Beyond accurate DSB repair, this capacity of HR to spatially associates homologous molecules is also harnessed for homolog pairing in meiosis. The goal of “3D-loop” is to tackle two long lasting conundrums: the fundamental homology search mechanism that achieves accurate and efficient identification of a single homologous donor in the vastness of the genome and nucleus, and how this mechanism is adapted for the purpose of homologs attachment in meiosis.
I overcame the main hurdle to study these core steps of HR by developing a suite of proximity ligation-based methodologies and experimental systems to physically detect joint molecules in yeast cells. It revealed elaborate regulation controlling D-loop dynamics and a novel class of joint molecules. This proposal builds upon these methodologies and findings to first address basic properties of the homology sampling process by the NPF and the role of D-loop dynamics, with the long-term goal to establish a quantitative framework of homology search in mitotic cells (WP1). Second, the meiosis-specific regulation of homology search leading to homolog pairing likely integrates chromosomal-scale information. Genome re-synthesis and engineering approaches will be deployed to (i) achieve a quantitative and dynamic cartography of the cytological and molecular events of meiosis over a large chromosomal region, (ii) probe cis-acting regulations at the chromosomal scale, and (iii) revisit the molecular paradigm for crossover formation (WP2). We expect this project to shed light on the fundamental process of homology search and its involvement in the chromosome pairing phenomenon lying at the basis of sexual reproduction.
Max ERC Funding
1 499 779 €
Duration
Start date: 2020-01-01, End date: 2024-12-31
Project acronym 3DEpi
Project Transgenerational epigenetic inheritance of chromatin states : the role of Polycomb and 3D chromosome architecture
Researcher (PI) Giacomo CAVALLI
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Advanced Grant (AdG), LS2, ERC-2017-ADG
Summary Epigenetic inheritance entails transmission of phenotypic traits not encoded in the DNA sequence and, in the most extreme case, Transgenerational Epigenetic Inheritance (TEI) involves transmission of memory through multiple generations. Very little is known on the mechanisms governing TEI and this is the subject of the present proposal. By transiently enhancing long-range chromatin interactions, we recently established isogenic Drosophila epilines that carry stable alternative epialleles, defined by differential levels of the Polycomb-dependent H3K27me3 mark. Furthermore, we extended our paradigm to natural phenotypes. These are ideal systems to study the role of Polycomb group (PcG) proteins and other components in regulating nuclear organization and epigenetic inheritance of chromatin states. The present project conjugates genetics, epigenomics, imaging and molecular biology to reach three critical aims.
Aim 1: Analysis of the molecular mechanisms regulating Polycomb-mediated TEI. We will identify the DNA, protein and RNA components that trigger and maintain transgenerational chromatin inheritance as well as their mechanisms of action.
Aim 2: Role of 3D genome organization in the regulation of TEI. We will analyze the developmental dynamics of TEI-inducing long-range chromatin interactions, identify chromatin components mediating 3D chromatin contacts and characterize their function in the TEI process.
Aim 3: Identification of a broader role of TEI during development. TEI might reflect a normal role of PcG components in the transmission of parental chromatin onto the next embryonic generation. We will explore this possibility by establishing other TEI paradigms and by relating TEI to the normal PcG function in these systems and in normal development.
This research program will unravel the biological significance and the molecular underpinnings of TEI and lead the way towards establishing this area of research into a consolidated scientific discipline.
Summary
Epigenetic inheritance entails transmission of phenotypic traits not encoded in the DNA sequence and, in the most extreme case, Transgenerational Epigenetic Inheritance (TEI) involves transmission of memory through multiple generations. Very little is known on the mechanisms governing TEI and this is the subject of the present proposal. By transiently enhancing long-range chromatin interactions, we recently established isogenic Drosophila epilines that carry stable alternative epialleles, defined by differential levels of the Polycomb-dependent H3K27me3 mark. Furthermore, we extended our paradigm to natural phenotypes. These are ideal systems to study the role of Polycomb group (PcG) proteins and other components in regulating nuclear organization and epigenetic inheritance of chromatin states. The present project conjugates genetics, epigenomics, imaging and molecular biology to reach three critical aims.
Aim 1: Analysis of the molecular mechanisms regulating Polycomb-mediated TEI. We will identify the DNA, protein and RNA components that trigger and maintain transgenerational chromatin inheritance as well as their mechanisms of action.
Aim 2: Role of 3D genome organization in the regulation of TEI. We will analyze the developmental dynamics of TEI-inducing long-range chromatin interactions, identify chromatin components mediating 3D chromatin contacts and characterize their function in the TEI process.
Aim 3: Identification of a broader role of TEI during development. TEI might reflect a normal role of PcG components in the transmission of parental chromatin onto the next embryonic generation. We will explore this possibility by establishing other TEI paradigms and by relating TEI to the normal PcG function in these systems and in normal development.
This research program will unravel the biological significance and the molecular underpinnings of TEI and lead the way towards establishing this area of research into a consolidated scientific discipline.
Max ERC Funding
2 500 000 €
Duration
Start date: 2018-11-01, End date: 2023-10-31
Project acronym 4D-GenEx
Project Spatio-temporal Organization and Expression of the Genome
Researcher (PI) Antoine COULON
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Starting Grant (StG), LS2, ERC-2017-STG
Summary This project investigates the two-way relationship between spatio-temporal genome organization and coordinated gene regulation, through an approach at the interface between physics, computer science and biology.
In the nucleus, preferred positions are observed from chromosomes to single genes, in relation to normal and pathological cellular states. Evidence indicates a complex spatio-temporal coupling between co-regulated genes: e.g. certain genes cluster spatially when responding to similar factors and transcriptional noise patterns suggest domain-wide mechanisms. Yet, no individual experiment allows probing transcriptional coordination in 4 dimensions (FISH, live locus tracking, Hi-C...). Interpreting such data also critically requires theory (stochastic processes, statistical physics…). A lack of appropriate experimental/analytical approaches is impairing our understanding of the 4D genome.
Our proposal combines cutting-edge single-molecule imaging, signal-theory data analysis and physical modeling to study how genes coordinate in space and time in a single nucleus. Our objectives are to understand (a) competition/recycling of shared resources between genes within subnuclear compartments, (b) how enhancers communicate with genes domain-wide, and (c) the role of local conformational dynamics and supercoiling in gene co-regulation. Our organizing hypothesis is that, by acting on their microenvironment, genes shape their co-expression with other genes.
Building upon my expertise, we will use dual-color MS2/PP7 RNA labeling to visualize for the first time transcription and motion of pairs of hormone-responsive genes in real time. With our innovative signal analysis tools, we will extract spatio-temporal signatures of underlying processes, which we will investigate with stochastic modeling and validate through experimental perturbations. We expect to uncover how the functional organization of the linear genome relates to its physical properties and dynamics in 4D.
Summary
This project investigates the two-way relationship between spatio-temporal genome organization and coordinated gene regulation, through an approach at the interface between physics, computer science and biology.
In the nucleus, preferred positions are observed from chromosomes to single genes, in relation to normal and pathological cellular states. Evidence indicates a complex spatio-temporal coupling between co-regulated genes: e.g. certain genes cluster spatially when responding to similar factors and transcriptional noise patterns suggest domain-wide mechanisms. Yet, no individual experiment allows probing transcriptional coordination in 4 dimensions (FISH, live locus tracking, Hi-C...). Interpreting such data also critically requires theory (stochastic processes, statistical physics…). A lack of appropriate experimental/analytical approaches is impairing our understanding of the 4D genome.
Our proposal combines cutting-edge single-molecule imaging, signal-theory data analysis and physical modeling to study how genes coordinate in space and time in a single nucleus. Our objectives are to understand (a) competition/recycling of shared resources between genes within subnuclear compartments, (b) how enhancers communicate with genes domain-wide, and (c) the role of local conformational dynamics and supercoiling in gene co-regulation. Our organizing hypothesis is that, by acting on their microenvironment, genes shape their co-expression with other genes.
Building upon my expertise, we will use dual-color MS2/PP7 RNA labeling to visualize for the first time transcription and motion of pairs of hormone-responsive genes in real time. With our innovative signal analysis tools, we will extract spatio-temporal signatures of underlying processes, which we will investigate with stochastic modeling and validate through experimental perturbations. We expect to uncover how the functional organization of the linear genome relates to its physical properties and dynamics in 4D.
Max ERC Funding
1 499 750 €
Duration
Start date: 2018-04-01, End date: 2023-03-31
Project acronym AnoPath
Project Genetics of mosquito resistance to pathogens
Researcher (PI) Kenneth Du Souchet Vernick
Host Institution (HI) INSTITUT PASTEUR
Call Details Advanced Grant (AdG), LS2, ERC-2012-ADG_20120314
Summary Malaria parasite infection in humans has been called “the strongest known force for evolutionary selection in the recent history of the human genome”, and I hypothesize that a similar statement may apply to the mosquito vector, which is the definitive host of the malaria parasite. We previously discovered efficient malaria-resistance mechanisms in natural populations of the African malaria vector, Anopheles gambiae. Aim 1 of the proposed project will implement a novel genetic mapping design to systematically survey the mosquito population for common and rare genetic variants of strong effect against the human malaria parasite, Plasmodium falciparum. A product of the mapping design will be living mosquito families carrying the resistance loci. Aim 2 will use the segregating families to functionally dissect the underlying molecular mechanisms controlled by the loci, including determination of the pathogen specificity spectra of the host-defense traits. Aim 3 targets arbovirus transmission, where Anopheles mosquitoes transmit human malaria but not arboviruses such as Dengue and Chikungunya, even though the two mosquitoes bite the same people and are exposed to the same pathogens, often in malaria-arbovirus co-infections. We will use deep-sequencing to detect processing of the arbovirus dsRNA intermediates of replication produced by the RNAi pathway of the mosquitoes. The results will reveal important new information about differences in the efficiency and quality of the RNAi response between mosquitoes, which is likely to underlie at least part of the host specificity of arbovirus transmission. The 3 Aims will make significant contributions to understanding malaria and arbovirus transmission, major global public health problems, will aid the development of a next generation of vector surveillance and control tools, and will produce a definitive description of the major genetic factors influencing host-pathogen interactions in mosquito immunity.
Summary
Malaria parasite infection in humans has been called “the strongest known force for evolutionary selection in the recent history of the human genome”, and I hypothesize that a similar statement may apply to the mosquito vector, which is the definitive host of the malaria parasite. We previously discovered efficient malaria-resistance mechanisms in natural populations of the African malaria vector, Anopheles gambiae. Aim 1 of the proposed project will implement a novel genetic mapping design to systematically survey the mosquito population for common and rare genetic variants of strong effect against the human malaria parasite, Plasmodium falciparum. A product of the mapping design will be living mosquito families carrying the resistance loci. Aim 2 will use the segregating families to functionally dissect the underlying molecular mechanisms controlled by the loci, including determination of the pathogen specificity spectra of the host-defense traits. Aim 3 targets arbovirus transmission, where Anopheles mosquitoes transmit human malaria but not arboviruses such as Dengue and Chikungunya, even though the two mosquitoes bite the same people and are exposed to the same pathogens, often in malaria-arbovirus co-infections. We will use deep-sequencing to detect processing of the arbovirus dsRNA intermediates of replication produced by the RNAi pathway of the mosquitoes. The results will reveal important new information about differences in the efficiency and quality of the RNAi response between mosquitoes, which is likely to underlie at least part of the host specificity of arbovirus transmission. The 3 Aims will make significant contributions to understanding malaria and arbovirus transmission, major global public health problems, will aid the development of a next generation of vector surveillance and control tools, and will produce a definitive description of the major genetic factors influencing host-pathogen interactions in mosquito immunity.
Max ERC Funding
2 307 800 €
Duration
Start date: 2013-03-01, End date: 2018-02-28
Project acronym BactRNA
Project Bacterial small RNAs networks unravelling novel features of transcription and translation
Researcher (PI) Maude Audrey Guillier
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Consolidator Grant (CoG), LS2, ERC-2018-COG
Summary Regulation of gene expression plays a key role in the ability of bacteria to rapidly adapt to changing environments and to colonize extremely diverse habitats. The relatively recent discovery of a plethora of small regulatory RNAs and the beginning of their characterization has unravelled new aspects of bacterial gene expression. First, the expression of many bacterial genes responds to a complex network of both transcriptional and post-transcriptional regulators. However, the properties of the resulting regulatory circuits on the dynamics of gene expression and in the bacterial adaptive response have been poorly addressed so far. In a first part of this project, we will tackle this question by characterizing the circuits that are formed between two widespread classes of bacterial regulators, the sRNAs and the two-component systems, which act at the post-transcriptional and the transcriptional level, respectively. The study of sRNAs also led to major breakthroughs regarding the basic mechanisms of gene expression. In particular, we recently showed that repressor sRNAs can target activating stem-loop structures located within the coding region of mRNAs that promote translation initiation, in striking contrast with the previously recognized inhibitory role of mRNA structures in translation. The second objective of this project is thus to draw an unprecedented map of non-canonical translation initiation events and their regulation by sRNAs.
Overall, this project will greatly improve our understanding of how bacteria can so rapidly and successfully adapt to many different environments, and in the long term, provide clues towards the development of anti-bacterial strategies.
Summary
Regulation of gene expression plays a key role in the ability of bacteria to rapidly adapt to changing environments and to colonize extremely diverse habitats. The relatively recent discovery of a plethora of small regulatory RNAs and the beginning of their characterization has unravelled new aspects of bacterial gene expression. First, the expression of many bacterial genes responds to a complex network of both transcriptional and post-transcriptional regulators. However, the properties of the resulting regulatory circuits on the dynamics of gene expression and in the bacterial adaptive response have been poorly addressed so far. In a first part of this project, we will tackle this question by characterizing the circuits that are formed between two widespread classes of bacterial regulators, the sRNAs and the two-component systems, which act at the post-transcriptional and the transcriptional level, respectively. The study of sRNAs also led to major breakthroughs regarding the basic mechanisms of gene expression. In particular, we recently showed that repressor sRNAs can target activating stem-loop structures located within the coding region of mRNAs that promote translation initiation, in striking contrast with the previously recognized inhibitory role of mRNA structures in translation. The second objective of this project is thus to draw an unprecedented map of non-canonical translation initiation events and their regulation by sRNAs.
Overall, this project will greatly improve our understanding of how bacteria can so rapidly and successfully adapt to many different environments, and in the long term, provide clues towards the development of anti-bacterial strategies.
Max ERC Funding
1 999 754 €
Duration
Start date: 2019-09-01, End date: 2024-08-31
Project acronym CDNF
Project Compartmentalization and dynamics of Nuclear functions
Researcher (PI) Angela Taddei
Host Institution (HI) INSTITUT CURIE
Call Details Starting Grant (StG), LS2, ERC-2007-StG
Summary The eukaryotic genome is packaged into large-scale chromatin structures that occupy distinct domains in the nucleus and this organization is now seen as a key contributor to genome functions. Two key functions of the genome can take advantage of nuclear organization: regulated gene expression and the propagation of a stable genome. To understand these fundamental processes, we have chosen to use yeast as a model system that allows genetics, molecular biology and advanced live microscopy approaches to be combined. Budding yeast have been very powerful to demonstrate that gene position can play an active role in regulating gene expression. Distinct subcompartments dedicated to either gene silencing or activation of specific genes are positioned at the nuclear periphery. To gain insight into the mechanisms underlying this sub-compartmentalization, we will address three complementary issues: - What are the mechanisms involved in the establishment and maintenance of silent nuclear compartments? - How and why are some activated genes recruited to the nuclear periphery? - What are the relationships between repressive and activating nuclear compartments? Concerning the maintenance of genome integrity, recent advances in yeast highlight the importance of nuclear architecture. However, how nuclear organization influences the formation and processing of DNA lesions remain poorly understood. We will focus on two main questions: - How and where in the nucleus are double strand breaks recognized, processed, and repaired? - Where do breaks or gaps resulting from replicative stress at 'fragile sites' arise in the nucleus and how does nuclear organization influence their stability? We hope to gain a better understanding of the mechanisms presiding nuclear organization and its importance for genome functions. These mechanisms are likely to be conserved and will be subsequently tested in higher eukaryotic cells.
Summary
The eukaryotic genome is packaged into large-scale chromatin structures that occupy distinct domains in the nucleus and this organization is now seen as a key contributor to genome functions. Two key functions of the genome can take advantage of nuclear organization: regulated gene expression and the propagation of a stable genome. To understand these fundamental processes, we have chosen to use yeast as a model system that allows genetics, molecular biology and advanced live microscopy approaches to be combined. Budding yeast have been very powerful to demonstrate that gene position can play an active role in regulating gene expression. Distinct subcompartments dedicated to either gene silencing or activation of specific genes are positioned at the nuclear periphery. To gain insight into the mechanisms underlying this sub-compartmentalization, we will address three complementary issues: - What are the mechanisms involved in the establishment and maintenance of silent nuclear compartments? - How and why are some activated genes recruited to the nuclear periphery? - What are the relationships between repressive and activating nuclear compartments? Concerning the maintenance of genome integrity, recent advances in yeast highlight the importance of nuclear architecture. However, how nuclear organization influences the formation and processing of DNA lesions remain poorly understood. We will focus on two main questions: - How and where in the nucleus are double strand breaks recognized, processed, and repaired? - Where do breaks or gaps resulting from replicative stress at 'fragile sites' arise in the nucleus and how does nuclear organization influence their stability? We hope to gain a better understanding of the mechanisms presiding nuclear organization and its importance for genome functions. These mechanisms are likely to be conserved and will be subsequently tested in higher eukaryotic cells.
Max ERC Funding
1 000 000 €
Duration
Start date: 2008-09-01, End date: 2014-05-31
Project acronym CENEVO
Project A new paradigm for centromere biology:Evolution and mechanism of CenH3-independent chromosome segregation in holocentric insects
Researcher (PI) Ines DRINNENBERG
Host Institution (HI) INSTITUT CURIE
Call Details Starting Grant (StG), LS2, ERC-2017-STG
Summary Faithful chromosome segregation in all eukaryotes relies on centromeres, the chromosomal sites that recruit kinetochore proteins and mediate spindle attachment during cell division. Fundamental to centromere function is a histone H3 variant, CenH3, that initiates kinetochore assembly on centromeric DNA. CenH3 is conserved throughout most eukaryotes; its deletion is lethal in all organisms tested. These findings established the paradigm that CenH3 is an absolute requirement for centromere function. My recent findings undermined this paradigm of CenH3 essentiality. I showed that CenH3 was lost independently in four lineages of insects. These losses are concomitant with dramatic changes in their centromeric architecture, in which each lineage independently transitioned from monocentromeres (where microtubules attach to a single chromosomal region) to holocentromeres (where microtubules attach along the entire length of the chromosome). Here, I aim to characterize this unique CenH3-deficient chromosome segregation pathway. Using proteomic and genomic approaches in lepidopteran cell lines, I will determine the mechanism of CenH3-independent kinetochore assembly that led to the establishment of their holocentric architecture. Using comparative genomic approaches, I will determine whether this kinetochore assembly pathway has recurrently evolved over the course of 400 million years of evolution and its impact on the chromosome segregation machinery.
My discovery of CenH3 loss in holocentric insects establishes a new class of centromeres. My research will reveal how CenH3 that is essential in most other eukaryotes, could have become dispensable in holocentric insects. Since the evolution of this CenH3-independent chromosome segregation pathway is associated with the independent rises of holocentric architectures, my research will also provide the first insights into the transition from a monocentromere to a holocentromere.
Summary
Faithful chromosome segregation in all eukaryotes relies on centromeres, the chromosomal sites that recruit kinetochore proteins and mediate spindle attachment during cell division. Fundamental to centromere function is a histone H3 variant, CenH3, that initiates kinetochore assembly on centromeric DNA. CenH3 is conserved throughout most eukaryotes; its deletion is lethal in all organisms tested. These findings established the paradigm that CenH3 is an absolute requirement for centromere function. My recent findings undermined this paradigm of CenH3 essentiality. I showed that CenH3 was lost independently in four lineages of insects. These losses are concomitant with dramatic changes in their centromeric architecture, in which each lineage independently transitioned from monocentromeres (where microtubules attach to a single chromosomal region) to holocentromeres (where microtubules attach along the entire length of the chromosome). Here, I aim to characterize this unique CenH3-deficient chromosome segregation pathway. Using proteomic and genomic approaches in lepidopteran cell lines, I will determine the mechanism of CenH3-independent kinetochore assembly that led to the establishment of their holocentric architecture. Using comparative genomic approaches, I will determine whether this kinetochore assembly pathway has recurrently evolved over the course of 400 million years of evolution and its impact on the chromosome segregation machinery.
My discovery of CenH3 loss in holocentric insects establishes a new class of centromeres. My research will reveal how CenH3 that is essential in most other eukaryotes, could have become dispensable in holocentric insects. Since the evolution of this CenH3-independent chromosome segregation pathway is associated with the independent rises of holocentric architectures, my research will also provide the first insights into the transition from a monocentromere to a holocentromere.
Max ERC Funding
1 497 500 €
Duration
Start date: 2018-04-01, End date: 2023-03-31
Project acronym CHROMTOPOLOGY
Project Understanding and manipulating the dynamics of chromosome topologies in transcriptional control
Researcher (PI) Thomas, Ivor Sexton
Host Institution (HI) CENTRE EUROPEEN DE RECHERCHE EN BIOLOGIE ET MEDECINE
Call Details Starting Grant (StG), LS2, ERC-2015-STG
Summary Transcriptional regulation of genes in eukaryotic cells requires a complex and highly regulated interplay of chromatin environment, epigenetic status of target sequences and several different transcription factors. Eukaryotic genomes are tightly packaged within nuclei, yet must be accessible for transcription, replication and repair. A striking correlation exists between chromatin topology and underlying gene activity. According to the textbook view, chromatin loops bring genes into direct contact with distal regulatory elements, such as enhancers. Moreover, we and others have shown that genomes are organized into discretely folded megabase-sized regions, denoted as topologically associated domains (TADs), which seem to correlate well with transcription activity and histone modifications. However, it is unknown whether chromosome folding is a cause or consequence of underlying gene function.
To better understand the role of genome organization in transcription regulation, I will address the following questions:
(i) How are chromatin configurations altered during transcriptional changes accompanying development?
(ii) What are the real-time kinetics and cell-to-cell variabilities of chromatin interactions and TAD architectures?
(iii) Can chromatin loops be engineered de novo, and do they influence gene expression?
(iv) What genetic elements and trans-acting factors are required to organize TADs?
To address these fundamental questions, I will use a combination of novel technologies and approaches, such as Hi-C, CRISPR knock-ins, ANCHOR tagging of DNA loci, high- and super-resolution single-cell imaging, genome-wide screens and optogenetics, in order to both study and engineer chromatin architectures.
These studies will give groundbreaking insight into if and how chromatin topology regulates transcription. Thus, I anticipate that the results of this project will have a major impact on the field and will lead to a new paradigm for metazoan transcription control.
Summary
Transcriptional regulation of genes in eukaryotic cells requires a complex and highly regulated interplay of chromatin environment, epigenetic status of target sequences and several different transcription factors. Eukaryotic genomes are tightly packaged within nuclei, yet must be accessible for transcription, replication and repair. A striking correlation exists between chromatin topology and underlying gene activity. According to the textbook view, chromatin loops bring genes into direct contact with distal regulatory elements, such as enhancers. Moreover, we and others have shown that genomes are organized into discretely folded megabase-sized regions, denoted as topologically associated domains (TADs), which seem to correlate well with transcription activity and histone modifications. However, it is unknown whether chromosome folding is a cause or consequence of underlying gene function.
To better understand the role of genome organization in transcription regulation, I will address the following questions:
(i) How are chromatin configurations altered during transcriptional changes accompanying development?
(ii) What are the real-time kinetics and cell-to-cell variabilities of chromatin interactions and TAD architectures?
(iii) Can chromatin loops be engineered de novo, and do they influence gene expression?
(iv) What genetic elements and trans-acting factors are required to organize TADs?
To address these fundamental questions, I will use a combination of novel technologies and approaches, such as Hi-C, CRISPR knock-ins, ANCHOR tagging of DNA loci, high- and super-resolution single-cell imaging, genome-wide screens and optogenetics, in order to both study and engineer chromatin architectures.
These studies will give groundbreaking insight into if and how chromatin topology regulates transcription. Thus, I anticipate that the results of this project will have a major impact on the field and will lead to a new paradigm for metazoan transcription control.
Max ERC Funding
1 500 000 €
Duration
Start date: 2016-06-01, End date: 2021-05-31
Project acronym DARK
Project Dark matter of the human transcriptome: Functional study of the antisense Long Noncoding RNAs and Molecular Mechanisms of Action
Researcher (PI) Antonin Morillon
Host Institution (HI) INSTITUT CURIE
Call Details Consolidator Grant (CoG), LS2, ERC-2013-CoG
Summary 98% of the human genome is non-protein coding raising the question of the role of the dark matter of the genome. It is now admitted that pervasive transcription generates thousands of noncoding transcripts that regulate gene expression and have broad impacts on development and disease. Among the long non coding (lnc)RNAs, antisense transcripts have been poorly studied despite their putative regulatory importance. Several functional examples include X-chromosome inactivation, maintenance of pluripotency and transcriptional regulation. However, no systematic study has yet addressed the comprehensive functional description of human antisense ncRNA, mainly because of technological issues and their low abundance. Indeed, in budding yeast S. cerevisiae, our group showed the existence of an entire class of antisense regulatory lncRNA extremely sensitive to RNA decay pathways, impinging their study so far. The roles for yeast antisense lncRNAs in shaping the epigenome raises important questions: What are the molecular and biochemical mechanisms by which antisense lncRNAs carry out their functions and are they functionally conserved in human cells? We propose that the dark side of the non-coding genome is another layer of gene regulation complexity that needs to be deciphered.
With this proposal, we aim to draw the first exhaustive catalog of human antisense lncRNA in various cell types and tissues using up to date High throughput technologies and bioinformatics pipelines. Second, we propose to determine the functional role of antisense lncRNA on genome expression and stability in the context of cellular stress and cancer. We anticipate that powerful and modern genetic tools such DNA-mediated gene inactivation (ASO) and TALEN approaches will allow precise antisense genes manipulation never achieved so far. Our project is strongly supported by preliminary data indicating an unexpected large number of hidden antisense lncRNA in human cells controlled by RNA decay pathways.
Summary
98% of the human genome is non-protein coding raising the question of the role of the dark matter of the genome. It is now admitted that pervasive transcription generates thousands of noncoding transcripts that regulate gene expression and have broad impacts on development and disease. Among the long non coding (lnc)RNAs, antisense transcripts have been poorly studied despite their putative regulatory importance. Several functional examples include X-chromosome inactivation, maintenance of pluripotency and transcriptional regulation. However, no systematic study has yet addressed the comprehensive functional description of human antisense ncRNA, mainly because of technological issues and their low abundance. Indeed, in budding yeast S. cerevisiae, our group showed the existence of an entire class of antisense regulatory lncRNA extremely sensitive to RNA decay pathways, impinging their study so far. The roles for yeast antisense lncRNAs in shaping the epigenome raises important questions: What are the molecular and biochemical mechanisms by which antisense lncRNAs carry out their functions and are they functionally conserved in human cells? We propose that the dark side of the non-coding genome is another layer of gene regulation complexity that needs to be deciphered.
With this proposal, we aim to draw the first exhaustive catalog of human antisense lncRNA in various cell types and tissues using up to date High throughput technologies and bioinformatics pipelines. Second, we propose to determine the functional role of antisense lncRNA on genome expression and stability in the context of cellular stress and cancer. We anticipate that powerful and modern genetic tools such DNA-mediated gene inactivation (ASO) and TALEN approaches will allow precise antisense genes manipulation never achieved so far. Our project is strongly supported by preliminary data indicating an unexpected large number of hidden antisense lncRNA in human cells controlled by RNA decay pathways.
Max ERC Funding
1 998 884 €
Duration
Start date: 2014-12-01, End date: 2019-11-30
Project acronym DECODE
Project Decoding the complexity of quantitative natural variation in Arabidopsis thaliana
Researcher (PI) Olivier Loudet
Host Institution (HI) INSTITUT NATIONAL DE RECHERCHE POUR L'AGRICULTURE, L'ALIMENTATION ET L'ENVIRONNEMENT
Call Details Starting Grant (StG), LS2, ERC-2009-StG
Summary Following a long history of quantitative genetics in crop plants, it now becomes feasible to use naturally-occuring variation contained in Arabidopsis thaliana accessions (lines isolated from natural populations) as the source of quantitative genomics approaches, designed to map QTLs and resolve them at the gene level. Apart from being able to exploit in multiple genetic backgrounds allelic variation that cannot be easily generated by conventional mutagenesis, the (relatively few) success of the QTL studies has often been because of the use of quantitative phenotyping, as opposed to the qualitative gauges used in typical mutant screens. Among the various genetic mechanisms responsible for natural variation that have just started to be revealed, cis-acting regulation is potentially of large impact, despite remaining more difficult to recognize and confirm. The objective of this project is to apply genome-wide quantitative molecular genetics to both, a very integrative and classical quantitative trait (growth in interaction with the environment) and a molecular trait a priori more directly linked to the source of variation (gene expression under cis-regulation). We propose to use a combination of our unique high-troughput phenotyping robot, fine-mapping, complementation approaches and association genetics to pinpoint a significant number of QTLs and eQTLs to the gene level and identify causative polymorphisms and the molecular variation controlling natural diversity. Working at an unprecedented scale should finally allow to resolve enough quantitative loci and pay a significant contribution to drawing a general picture as to how and where in the pathways adaptation is shaping natural variation and improve our understanding of the transcriptional cis-regulatory code.
Summary
Following a long history of quantitative genetics in crop plants, it now becomes feasible to use naturally-occuring variation contained in Arabidopsis thaliana accessions (lines isolated from natural populations) as the source of quantitative genomics approaches, designed to map QTLs and resolve them at the gene level. Apart from being able to exploit in multiple genetic backgrounds allelic variation that cannot be easily generated by conventional mutagenesis, the (relatively few) success of the QTL studies has often been because of the use of quantitative phenotyping, as opposed to the qualitative gauges used in typical mutant screens. Among the various genetic mechanisms responsible for natural variation that have just started to be revealed, cis-acting regulation is potentially of large impact, despite remaining more difficult to recognize and confirm. The objective of this project is to apply genome-wide quantitative molecular genetics to both, a very integrative and classical quantitative trait (growth in interaction with the environment) and a molecular trait a priori more directly linked to the source of variation (gene expression under cis-regulation). We propose to use a combination of our unique high-troughput phenotyping robot, fine-mapping, complementation approaches and association genetics to pinpoint a significant number of QTLs and eQTLs to the gene level and identify causative polymorphisms and the molecular variation controlling natural diversity. Working at an unprecedented scale should finally allow to resolve enough quantitative loci and pay a significant contribution to drawing a general picture as to how and where in the pathways adaptation is shaping natural variation and improve our understanding of the transcriptional cis-regulatory code.
Max ERC Funding
1 742 113 €
Duration
Start date: 2010-02-01, End date: 2016-01-31
