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 ChaperoneRegulome
Project ChaperoneRegulome: Understanding cell-type-specificity of chaperone regulation
Researcher (PI) Ritwick SAWARKAR
Host Institution (HI) THE CHANCELLOR MASTERS AND SCHOLARSOF THE UNIVERSITY OF CAMBRIDGE
Call Details Consolidator Grant (CoG), LS3, ERC-2018-COG
Summary Protein misfolding causes devastating health conditions such as neurodegeneration. Although the disease-causing protein is widely expressed, its misfolding occurs only in certain cell-types such as neurons. What governs the susceptibility of some tissues to misfolding is a fundamental question with biomedical relevance.
Molecular chaperones help cellular proteins fold into their native conformation. Despite the generality of their function, chaperones are differentially expressed across various tissues. Moreover exposure to misfolding stress changes chaperone expression in a cell-type-dependent manner. Thus cell-type-specific regulation of chaperones is a major determinant of susceptibility to misfolding. The molecular mechanisms governing chaperone levels in different cell-types are not understood, forming the basis of this proposal. We will take a multidisciplinary approach to address two key questions: (1) How are chaperone levels co-ordinated with tissue-specific demands on protein folding? (2) How do different cell-types regulate chaperone genes when exposed to the same misfolding stress?
Cellular chaperone levels and their response to misfolding stress are both driven by transcriptional changes and influenced by chromatin. The proposed work will bring the conceptual, technological and computational advances of chromatin/ transcription field to understand chaperone biology and misfolding diseases. Using in vivo mouse model and in vitro differentiation model, we will investigate molecular mechanisms that control chaperone levels in relevant tissues. Our work will provide insights into functional specialization of chaperones driven by tissue-specific folding demands. We will develop a novel and ambitious approach to assess protein-folding capacity in single cells moving the chaperone field beyond state-of-the-art. Thus by implementing genetic, computational and biochemical approaches, we aim to understand cell-type-specificity of chaperone regulation.
Summary
Protein misfolding causes devastating health conditions such as neurodegeneration. Although the disease-causing protein is widely expressed, its misfolding occurs only in certain cell-types such as neurons. What governs the susceptibility of some tissues to misfolding is a fundamental question with biomedical relevance.
Molecular chaperones help cellular proteins fold into their native conformation. Despite the generality of their function, chaperones are differentially expressed across various tissues. Moreover exposure to misfolding stress changes chaperone expression in a cell-type-dependent manner. Thus cell-type-specific regulation of chaperones is a major determinant of susceptibility to misfolding. The molecular mechanisms governing chaperone levels in different cell-types are not understood, forming the basis of this proposal. We will take a multidisciplinary approach to address two key questions: (1) How are chaperone levels co-ordinated with tissue-specific demands on protein folding? (2) How do different cell-types regulate chaperone genes when exposed to the same misfolding stress?
Cellular chaperone levels and their response to misfolding stress are both driven by transcriptional changes and influenced by chromatin. The proposed work will bring the conceptual, technological and computational advances of chromatin/ transcription field to understand chaperone biology and misfolding diseases. Using in vivo mouse model and in vitro differentiation model, we will investigate molecular mechanisms that control chaperone levels in relevant tissues. Our work will provide insights into functional specialization of chaperones driven by tissue-specific folding demands. We will develop a novel and ambitious approach to assess protein-folding capacity in single cells moving the chaperone field beyond state-of-the-art. Thus by implementing genetic, computational and biochemical approaches, we aim to understand cell-type-specificity of chaperone regulation.
Max ERC Funding
1 992 500 €
Duration
Start date: 2020-01-01, End date: 2024-12-31
Project acronym CHROMABOLISM
Project Chromatin-localized central metabolism regulating gene expression and cell identity
Researcher (PI) Stefan KUBICEK
Host Institution (HI) CEMM - FORSCHUNGSZENTRUM FUER MOLEKULARE MEDIZIN GMBH
Call Details Consolidator Grant (CoG), LS3, ERC-2017-COG
Summary Epigenetics research has revealed that in the cell’s nucleus all kinds of biomolecules–DNA, RNAs, proteins, protein posttranslational modifications–are highly compartmentalized to occupy distinct chromatin territories and genomic loci, thereby contributing to gene regulation and cell identity. In contrast, small molecules and cellular metabolites are generally considered to passively enter the nucleus from the cytoplasm and to lack distinct subnuclear localization. The CHROMABOLISM proposal challenges this assumption based on preliminary data generated in my laboratory. I hypothesize that chromatin-bound enzymes of central metabolism and subnuclear metabolite gradients contribute to gene regulation and cellular identity.
To address this hypothesis, we will first systematically profile chromatin-bound metabolic enzymes, chart nuclear metabolomes across representative leukemia cell lines, and develop tools to measure local metabolite concentrations at distinct genomic loci. In a second step, we will then develop and apply technology to perturb these nuclear metabolite patterns by forcing the export of metabolic enzymes for the nucleus, aberrantly recruiting these enzymes to selected genomic loci, and perturbing metabolite patterns by addition and depletion of metabolites. In all these conditions we will measure the impact of nuclear metabolism on chromatin structure and gene expression. Based on the data obtained, we will model for the effects of cellular metabolites on cancer cell identity and proliferation. In line with the recent discovery of oncometabolites and the clinical use of antimetabolites, we expect to predict chromatin-bound metabolic enzymes that can be exploited as druggable targets in oncology. In a final aim we will validate these targets in leukemia and develop chemical probes against them.
Successful completion of this project has the potential to transform our understanding of nuclear metabolism in control of gene expression and cellular identity.
Summary
Epigenetics research has revealed that in the cell’s nucleus all kinds of biomolecules–DNA, RNAs, proteins, protein posttranslational modifications–are highly compartmentalized to occupy distinct chromatin territories and genomic loci, thereby contributing to gene regulation and cell identity. In contrast, small molecules and cellular metabolites are generally considered to passively enter the nucleus from the cytoplasm and to lack distinct subnuclear localization. The CHROMABOLISM proposal challenges this assumption based on preliminary data generated in my laboratory. I hypothesize that chromatin-bound enzymes of central metabolism and subnuclear metabolite gradients contribute to gene regulation and cellular identity.
To address this hypothesis, we will first systematically profile chromatin-bound metabolic enzymes, chart nuclear metabolomes across representative leukemia cell lines, and develop tools to measure local metabolite concentrations at distinct genomic loci. In a second step, we will then develop and apply technology to perturb these nuclear metabolite patterns by forcing the export of metabolic enzymes for the nucleus, aberrantly recruiting these enzymes to selected genomic loci, and perturbing metabolite patterns by addition and depletion of metabolites. In all these conditions we will measure the impact of nuclear metabolism on chromatin structure and gene expression. Based on the data obtained, we will model for the effects of cellular metabolites on cancer cell identity and proliferation. In line with the recent discovery of oncometabolites and the clinical use of antimetabolites, we expect to predict chromatin-bound metabolic enzymes that can be exploited as druggable targets in oncology. In a final aim we will validate these targets in leukemia and develop chemical probes against them.
Successful completion of this project has the potential to transform our understanding of nuclear metabolism in control of gene expression and cellular identity.
Max ERC Funding
1 980 916 €
Duration
Start date: 2018-05-01, End date: 2023-04-30
Project acronym ChromHeritance
Project Chromosome inheritance from mammalian oocytes to embryos
Researcher (PI) Kikue Tachibana-Konwalski
Host Institution (HI) INSTITUT FUER MOLEKULARE BIOTECHNOLOGIE GMBH
Call Details Starting Grant (StG), LS3, ERC-2013-StG
Summary One of the most dramatic transitions in biology is the oocyte-to-zygote transition. This refers to the maturation of the female germ cell or oocyte, which undergoes two rounds of meiotic chromosome segregation and, following fertilization, is converted to a mitotically dividing embryo. We aim to establish an innovative research program that addresses fundamental questions about the molecular processes controlling the mammalian oocyte-to-zygote transition to ensure faithful inheritance of genomes from one generation to the next. We are taking an interdisciplinary approach combining germ cell and chromosome biology with cell cycle and epigenetic studies to understand how maternal factors regulate chromosome segregation in oocytes and chromatin organization in the zygote. A molecular understanding of key players regulating these processes is a requisite step for investigating how their deterioration contributes to maternal age-related aneuploidy and infertility. Aneuploidy is the leading cause of mental retardation and spontaneous miscarriage. The current trend towards advanced maternal age has increased the frequency of trisomic fetuses by 71% in the past ten years. A better understanding of mammalian meiosis is therefore relevant to human reproductive health.
A special feature of the female germ line is that meiotic DNA replication occurs in the embryo but oocytes remain arrested until the first meiotic division is triggered months (mouse) or decades (human) later. The longevity of oocytes poses a challenge for the cohesin complex that must hold together sister chromatids from DNA synthesis until chromosome segregation. We specifically aim to: 1) elucidate how sister chromatid cohesion is maintained in mammalian oocytes, 2) identify mechanisms regulating cohesion in young and aged oocytes, and 3) investigate how the inheritance of genetic and resetting of epigenetic information is coordinated with cell cycle progression at the oocyte-to-zygote transition.
Summary
One of the most dramatic transitions in biology is the oocyte-to-zygote transition. This refers to the maturation of the female germ cell or oocyte, which undergoes two rounds of meiotic chromosome segregation and, following fertilization, is converted to a mitotically dividing embryo. We aim to establish an innovative research program that addresses fundamental questions about the molecular processes controlling the mammalian oocyte-to-zygote transition to ensure faithful inheritance of genomes from one generation to the next. We are taking an interdisciplinary approach combining germ cell and chromosome biology with cell cycle and epigenetic studies to understand how maternal factors regulate chromosome segregation in oocytes and chromatin organization in the zygote. A molecular understanding of key players regulating these processes is a requisite step for investigating how their deterioration contributes to maternal age-related aneuploidy and infertility. Aneuploidy is the leading cause of mental retardation and spontaneous miscarriage. The current trend towards advanced maternal age has increased the frequency of trisomic fetuses by 71% in the past ten years. A better understanding of mammalian meiosis is therefore relevant to human reproductive health.
A special feature of the female germ line is that meiotic DNA replication occurs in the embryo but oocytes remain arrested until the first meiotic division is triggered months (mouse) or decades (human) later. The longevity of oocytes poses a challenge for the cohesin complex that must hold together sister chromatids from DNA synthesis until chromosome segregation. We specifically aim to: 1) elucidate how sister chromatid cohesion is maintained in mammalian oocytes, 2) identify mechanisms regulating cohesion in young and aged oocytes, and 3) investigate how the inheritance of genetic and resetting of epigenetic information is coordinated with cell cycle progression at the oocyte-to-zygote transition.
Max ERC Funding
1 499 738 €
Duration
Start date: 2014-02-01, End date: 2019-01-31
Project acronym ChromoCellDev
Project Chromosome Architecture and the Fidelity of Mitosis during Development
Researcher (PI) Raquel Aguiar Cardoso de Oliveira
Host Institution (HI) FUNDACAO CALOUSTE GULBENKIAN
Call Details Starting Grant (StG), LS3, ERC-2014-STG
Summary Genome stability relies on accurate partition of the genome during nuclear division. Proper mitosis, in turn, depends on changes in chromosome organization, such as chromosome condensation and sister chromatid cohesion. Despite the importance of these structural changes, chromatin itself has been long assumed to play a rather passive role during mitosis and chromosomes are usually compared to a “corpse at a funeral: they provide the reason for the proceedings but do not take an active part in them.” (Mazia, 1961). Recent evidence, however, suggests that chromosomes play a more active role in the process of their own segregation. The present proposal tests the “active chromosome” hypothesis by investigating how chromosome morphology influences the fidelity of mitosis. I will use innovative methods for acute protein inactivation, developed during my postdoctoral studies, to evaluate the role of two key protein complexes involved in mitotic chromosome architecture - Condensins and Cohesins. Using a multidisciplinary approach, combining acute protein inactivation, 3D-live cell imaging and quantitative methods, I propose to investigate the role of mitotic chromosomes in the fidelity of mitosis at three different levels. The first one will use novel approaches to uncover the process of mitotic chromosome assembly, which is still largely unknown. The second will explore how mitotic chromosomes take an active part in mitosis by examining how chromosome condensation and cohesion influence chromosome movement and the signalling of the surveillance mechanisms that control nuclear division. Lastly we will evaluate how mitotic errors arising from abnormal chromosome structure impact on development. We aim to evaluate, at the cellular and organism level, how the cell perceives such errors and how (indeed if) they tolerate mitotic abnormalities. By conceptually challenging the passive chromosome view this project has the potential to redefine the role of chromatin during mitosis.
Summary
Genome stability relies on accurate partition of the genome during nuclear division. Proper mitosis, in turn, depends on changes in chromosome organization, such as chromosome condensation and sister chromatid cohesion. Despite the importance of these structural changes, chromatin itself has been long assumed to play a rather passive role during mitosis and chromosomes are usually compared to a “corpse at a funeral: they provide the reason for the proceedings but do not take an active part in them.” (Mazia, 1961). Recent evidence, however, suggests that chromosomes play a more active role in the process of their own segregation. The present proposal tests the “active chromosome” hypothesis by investigating how chromosome morphology influences the fidelity of mitosis. I will use innovative methods for acute protein inactivation, developed during my postdoctoral studies, to evaluate the role of two key protein complexes involved in mitotic chromosome architecture - Condensins and Cohesins. Using a multidisciplinary approach, combining acute protein inactivation, 3D-live cell imaging and quantitative methods, I propose to investigate the role of mitotic chromosomes in the fidelity of mitosis at three different levels. The first one will use novel approaches to uncover the process of mitotic chromosome assembly, which is still largely unknown. The second will explore how mitotic chromosomes take an active part in mitosis by examining how chromosome condensation and cohesion influence chromosome movement and the signalling of the surveillance mechanisms that control nuclear division. Lastly we will evaluate how mitotic errors arising from abnormal chromosome structure impact on development. We aim to evaluate, at the cellular and organism level, how the cell perceives such errors and how (indeed if) they tolerate mitotic abnormalities. By conceptually challenging the passive chromosome view this project has the potential to redefine the role of chromatin during mitosis.
Max ERC Funding
1 492 000 €
Duration
Start date: 2015-10-01, End date: 2021-09-30
Project acronym CHROMOCOND
Project A molecular view of chromosome condensation
Researcher (PI) Frank Uhlmann
Host Institution (HI) CANCER RESEARCH UK LBG
Call Details Advanced Grant (AdG), LS3, ERC-2009-AdG
Summary Eukaryotic cells inherit much of their genomic information in the form of chromosomes during cell division. Centimetre-long DNA molecules are packed into micrometer-sized chromosomes to enable this process. How DNA is organised within mitotic chromosomes is still largely unknown. A key structural protein component of mitotic chromosomes, implicated in their compaction, is the condensin complex. In this proposal, we aim to elucidate the molecular architecture of mitotic chromosomes, taking advantage of new genomic techniques and the relatively simple genome organisation of yeast model systems. We will place particular emphasis on elucidating the contribution of the condensin complex, and the cell cycle regulation of its activities, in promoting chromosome condensation. Our previous work has provided genome-wide maps of condensin binding to budding and fission yeast chromosomes. We will continue to decipher the molecular determinants for condensin binding. To investigate how condensin mediates DNA compaction, we propose to generate chromosome-wide DNA/DNA proximity maps. Our approach will be an extension of the chromosome conformation capture (3C) technique. High throughput sequencing of interaction points has provided a first glimpse of the interactions that govern chromosome condensation. The role that condensin plays in promoting these interactions will be investigated. The contribution of condensin s ATP-dependent activities, and cell cycle-dependent post-translational modifications, will be studied. This will be complemented by mathematical modelling of the condensation process. In addition to chromosome condensation, condensin is required for resolution of sister chromatids in anaphase. We will develop an assay to study the catenation status of sister chromatids and how condensin may contribute to their topological resolution.
Summary
Eukaryotic cells inherit much of their genomic information in the form of chromosomes during cell division. Centimetre-long DNA molecules are packed into micrometer-sized chromosomes to enable this process. How DNA is organised within mitotic chromosomes is still largely unknown. A key structural protein component of mitotic chromosomes, implicated in their compaction, is the condensin complex. In this proposal, we aim to elucidate the molecular architecture of mitotic chromosomes, taking advantage of new genomic techniques and the relatively simple genome organisation of yeast model systems. We will place particular emphasis on elucidating the contribution of the condensin complex, and the cell cycle regulation of its activities, in promoting chromosome condensation. Our previous work has provided genome-wide maps of condensin binding to budding and fission yeast chromosomes. We will continue to decipher the molecular determinants for condensin binding. To investigate how condensin mediates DNA compaction, we propose to generate chromosome-wide DNA/DNA proximity maps. Our approach will be an extension of the chromosome conformation capture (3C) technique. High throughput sequencing of interaction points has provided a first glimpse of the interactions that govern chromosome condensation. The role that condensin plays in promoting these interactions will be investigated. The contribution of condensin s ATP-dependent activities, and cell cycle-dependent post-translational modifications, will be studied. This will be complemented by mathematical modelling of the condensation process. In addition to chromosome condensation, condensin is required for resolution of sister chromatids in anaphase. We will develop an assay to study the catenation status of sister chromatids and how condensin may contribute to their topological resolution.
Max ERC Funding
2 076 126 €
Duration
Start date: 2010-04-01, End date: 2015-03-31
Project acronym CHROMONUMBER
Project Chromosome number variations in vivo: probing mechanisms of genesis and elimination
Researcher (PI) Renata BASTO
Host Institution (HI) INSTITUT CURIE
Call Details Consolidator Grant (CoG), LS3, ERC-2016-COG
Summary How variations in whole chromosome number impact organism homeostasis remains an open question. Variations to the normal euploid genome content are frequently found in healthy animals and are thought to contribute with phenotypic variability in adverse situations. Yet they are also at the basis of several human diseases, including neuro-developmental disorders and cancer. Our preliminary data shows that physiological aneuploidy can be identified in certain cells during development. Moreover, we have observed that when induced through mutations, non-euploid cells are effectively eliminated from the cycling population. A quantitative view of the frequency of non-euploid karyotypes and the mechanisms underlying their genesis is lacking in the literature. Further, the tissue specific responses at play to eliminate non-euploid cells, when induced through mutations are not understood. The objectives of this proposal are to quantitatively assess the occurrence of physiological chromosome number variations gaining insight into mechanisms involved in generating it. Additionally, we will identify the tissue-specific pathways involved in maintaining organism homeostasis through the elimination of non-euploid cells. We will use a novel genetic approach to monitor individual chromosome loss at the level of the entire organism, combine it with quantitative methods and state-of-the art-microscopy, and focus on two model organisms - Drosophila and mouse - during development and adulthood. We predict that the findings resulting from this proposal will significantly impact the fields of cell, developmental and animal physiology, generating novel concepts that will bridge the existing gaps in the field, and expand our understanding of the links between karyotype variations, animal development and disease establishment.
Summary
How variations in whole chromosome number impact organism homeostasis remains an open question. Variations to the normal euploid genome content are frequently found in healthy animals and are thought to contribute with phenotypic variability in adverse situations. Yet they are also at the basis of several human diseases, including neuro-developmental disorders and cancer. Our preliminary data shows that physiological aneuploidy can be identified in certain cells during development. Moreover, we have observed that when induced through mutations, non-euploid cells are effectively eliminated from the cycling population. A quantitative view of the frequency of non-euploid karyotypes and the mechanisms underlying their genesis is lacking in the literature. Further, the tissue specific responses at play to eliminate non-euploid cells, when induced through mutations are not understood. The objectives of this proposal are to quantitatively assess the occurrence of physiological chromosome number variations gaining insight into mechanisms involved in generating it. Additionally, we will identify the tissue-specific pathways involved in maintaining organism homeostasis through the elimination of non-euploid cells. We will use a novel genetic approach to monitor individual chromosome loss at the level of the entire organism, combine it with quantitative methods and state-of-the art-microscopy, and focus on two model organisms - Drosophila and mouse - during development and adulthood. We predict that the findings resulting from this proposal will significantly impact the fields of cell, developmental and animal physiology, generating novel concepts that will bridge the existing gaps in the field, and expand our understanding of the links between karyotype variations, animal development and disease establishment.
Max ERC Funding
2 000 000 €
Duration
Start date: 2017-07-01, End date: 2022-06-30
Project acronym CHROMOOCYTE
Project Mechanisms of chromosome segregation in mammalian oocytes
Researcher (PI) Melina Schuh
Host Institution (HI) MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV
Call Details Starting Grant (StG), LS3, ERC-2013-StG
Summary All animal life starts with the fertilization of an egg. A haploid egg and a haploid sperm fuse and together they form a new genetically unique embryo. But surprisingly, eggs frequently contain an incorrect number of chromosomes. Depending on the age of the woman, 10-50% of eggs are chromosomally abnormal. This high percentage of abnormal eggs results from chromosome segregation errors during oocyte maturation, the process by which a diploid oocyte matures into a haploid egg. Thus, errors during meiosis in human oocytes are the most common cause of pregnancy losses and contribute to approximately 95% of human aneuploidy such as Down’s syndrome. Surprisingly, we still know very little about how mammalian oocytes mature into eggs, and it is still unclear why chromosome segregation during meiosis is so much more error-prone than during mitosis.
My proposal combines three innovative and complementary approaches towards understanding how homologous chromosomes are segregated and why oocyte maturation in mammals is so error-prone. Specifically, we will work towards the following three aims: 1. We will complete the first large scale screen for genes required for accurate progression through meiosis in mammalian oocytes and characterize the function of a few selected genes in detail. 2. We will analyse meiosis and investigate potential causes of chromosome segregation errors directly in live human oocytes. 3. We will study the function of an F-actin spindle and a chromosome-associated myosin that might be required for chromosome segregation in mammalian oocytes.
Because errors during oocyte maturation lead to pregnancy loss, birth defects and infertility, this work will not only provide important insights into fundamental cellular mechanisms, but will also have important implications for human health.
Summary
All animal life starts with the fertilization of an egg. A haploid egg and a haploid sperm fuse and together they form a new genetically unique embryo. But surprisingly, eggs frequently contain an incorrect number of chromosomes. Depending on the age of the woman, 10-50% of eggs are chromosomally abnormal. This high percentage of abnormal eggs results from chromosome segregation errors during oocyte maturation, the process by which a diploid oocyte matures into a haploid egg. Thus, errors during meiosis in human oocytes are the most common cause of pregnancy losses and contribute to approximately 95% of human aneuploidy such as Down’s syndrome. Surprisingly, we still know very little about how mammalian oocytes mature into eggs, and it is still unclear why chromosome segregation during meiosis is so much more error-prone than during mitosis.
My proposal combines three innovative and complementary approaches towards understanding how homologous chromosomes are segregated and why oocyte maturation in mammals is so error-prone. Specifically, we will work towards the following three aims: 1. We will complete the first large scale screen for genes required for accurate progression through meiosis in mammalian oocytes and characterize the function of a few selected genes in detail. 2. We will analyse meiosis and investigate potential causes of chromosome segregation errors directly in live human oocytes. 3. We will study the function of an F-actin spindle and a chromosome-associated myosin that might be required for chromosome segregation in mammalian oocytes.
Because errors during oocyte maturation lead to pregnancy loss, birth defects and infertility, this work will not only provide important insights into fundamental cellular mechanisms, but will also have important implications for human health.
Max ERC Funding
1 487 611 €
Duration
Start date: 2014-02-01, End date: 2019-01-31
Project acronym ChromoSOMe
Project Canonical and Non-canonical modes of Chromosome Segregation in Oocyte Meiosis
Researcher (PI) Julien Dumont
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Consolidator Grant (CoG), LS3, ERC-2018-COG
Summary Cell division is crucial for the development of complex organisms, for the homeostasis of tissues, and for the reproductive capacity of individuals. While most somatic cells are diploid and proliferate through mitosis, multiplication of sexually reproducing species relies on haploid gametes that are generated through a specialized cell division process called meiosis. To achieve this reduction in ploidy, two rounds of chromosome segregation follow a single phase of genome replication. Inaccuracy in this process leads to gametes that carry an incorrect number of chromosomes and to aneuploid embryos after fertilization. In their vast majority, these are non-viable and lead to spontaneous abortion: defective meiotic division is therefore a major obstacle in achieving reproduction. However, the key principles that drive this process are still poorly understood, one main reason being the diversity of the molecular scenarios that have been adopted across evolution to regulate oocyte chromosome segregation.
To dissect the key components of oocyte meiotic chromosome segregation, we propose to carry out a multi-disciplinary approach, combining several nematode species with the use of high-resolution live and electron microscopy, cutting edge genomic and proteomic technologies, and biochemistry coupled to in silico modeling. In Work Package 1 (WP1), we will analyze the molecular mechanisms controlling the self-assembly of the chromosome segregation machinery -the meiotic spindle- in the oocyte. WP2 will focus on defining how chromosome segregation is achieved in oocytes with non-canonical kinetochore geometry. WP3 aims at analyzing meiotic divisions in parthenogenetic nematodes with specific meiotic constraints, such as centrosomal oogenesis and unichromosomal genomes. By considering the wealth of mechanisms that can drive chromosome segregation in oocytes, this project will provide decisive steps towards understanding the essential and universal features of female meiosis.
Summary
Cell division is crucial for the development of complex organisms, for the homeostasis of tissues, and for the reproductive capacity of individuals. While most somatic cells are diploid and proliferate through mitosis, multiplication of sexually reproducing species relies on haploid gametes that are generated through a specialized cell division process called meiosis. To achieve this reduction in ploidy, two rounds of chromosome segregation follow a single phase of genome replication. Inaccuracy in this process leads to gametes that carry an incorrect number of chromosomes and to aneuploid embryos after fertilization. In their vast majority, these are non-viable and lead to spontaneous abortion: defective meiotic division is therefore a major obstacle in achieving reproduction. However, the key principles that drive this process are still poorly understood, one main reason being the diversity of the molecular scenarios that have been adopted across evolution to regulate oocyte chromosome segregation.
To dissect the key components of oocyte meiotic chromosome segregation, we propose to carry out a multi-disciplinary approach, combining several nematode species with the use of high-resolution live and electron microscopy, cutting edge genomic and proteomic technologies, and biochemistry coupled to in silico modeling. In Work Package 1 (WP1), we will analyze the molecular mechanisms controlling the self-assembly of the chromosome segregation machinery -the meiotic spindle- in the oocyte. WP2 will focus on defining how chromosome segregation is achieved in oocytes with non-canonical kinetochore geometry. WP3 aims at analyzing meiotic divisions in parthenogenetic nematodes with specific meiotic constraints, such as centrosomal oogenesis and unichromosomal genomes. By considering the wealth of mechanisms that can drive chromosome segregation in oocytes, this project will provide decisive steps towards understanding the essential and universal features of female meiosis.
Max ERC Funding
1 561 563 €
Duration
Start date: 2020-01-01, End date: 2024-12-31
Project acronym ChroNeuroRepair
Project Chromatin states in neurogenesis – from understanding chromatin loops to eliciting neurogenesis for repair
Researcher (PI) Magdalena Götz
Host Institution (HI) HELMHOLTZ ZENTRUM MUENCHEN DEUTSCHES FORSCHUNGSZENTRUM FUER GESUNDHEIT UND UMWELT GMBH
Call Details Advanced Grant (AdG), LS3, ERC-2013-ADG
Summary The mechanisms regulating neural stem cells and their progression to neurogenesis are important not only to understand brain development and evolution, but also to elicit neurogenesis after brain injury. Our recent findings imply novel chromatin-associated proteins in the regulation of neural stem cell fate and neurogenesis. Therefore this project aims to understand the molecular mechanisms of how these factors regulate neurogenesis in developing and adult mice (Aim1) and implement this knowledge for reprogramming glia into neurons after brain injury (Aim2). This will be pursued in mouse models in vivo (2.1) and with human glial cells derived from patient brain resections in vitro (2.2). It is well known that transcription factors need to alter the chromatin structure to achieve transcriptional regulation, but the factors involved in this regulation in neural stem and progenitor cells are still ill understood. Therefore the molecular function of the novel chromatin interacting protein Trnp1 with essential roles in neural stem cell (NSC) fate and the chromatin conformation mediated at neurogenic target genes by Pax6/Brg1-containing BAF complexes will be addressed in Aim1. Combined with genome-wide approaches to determine changes in chromatin conformation at neurogenic target gene sites this will greatly further our understanding of key roles of chromatin conformation in neural stem cells and neurogenesis. In Aim2 Trnp1 promoting neural stem cells fate and later acting neurogenic transcription factors will be used to improve neuronal reprogramming after stab wound injury in the murine brain in vivo and in patient-derived glial cells in vitro. Together with novel strategies to induce chromatin looping in a sequence-specific manner this project will not only advance our knowledge at the frontier of transcriptional regulation in neurogenesis, but also implement highly innovative approaches to utilize this knowledge for neuronal repair by direct reprogramming.
Summary
The mechanisms regulating neural stem cells and their progression to neurogenesis are important not only to understand brain development and evolution, but also to elicit neurogenesis after brain injury. Our recent findings imply novel chromatin-associated proteins in the regulation of neural stem cell fate and neurogenesis. Therefore this project aims to understand the molecular mechanisms of how these factors regulate neurogenesis in developing and adult mice (Aim1) and implement this knowledge for reprogramming glia into neurons after brain injury (Aim2). This will be pursued in mouse models in vivo (2.1) and with human glial cells derived from patient brain resections in vitro (2.2). It is well known that transcription factors need to alter the chromatin structure to achieve transcriptional regulation, but the factors involved in this regulation in neural stem and progenitor cells are still ill understood. Therefore the molecular function of the novel chromatin interacting protein Trnp1 with essential roles in neural stem cell (NSC) fate and the chromatin conformation mediated at neurogenic target genes by Pax6/Brg1-containing BAF complexes will be addressed in Aim1. Combined with genome-wide approaches to determine changes in chromatin conformation at neurogenic target gene sites this will greatly further our understanding of key roles of chromatin conformation in neural stem cells and neurogenesis. In Aim2 Trnp1 promoting neural stem cells fate and later acting neurogenic transcription factors will be used to improve neuronal reprogramming after stab wound injury in the murine brain in vivo and in patient-derived glial cells in vitro. Together with novel strategies to induce chromatin looping in a sequence-specific manner this project will not only advance our knowledge at the frontier of transcriptional regulation in neurogenesis, but also implement highly innovative approaches to utilize this knowledge for neuronal repair by direct reprogramming.
Max ERC Funding
2 376 560 €
Duration
Start date: 2014-02-01, End date: 2019-01-31
