ERC FUNDED PROJECTS

The brain evolves, develops, and operates in the context of animal movements. As a consequence, fundamental brain functions such as spatial perception and motor control critically depend on the precise knowledge of the ongoing body motion. An accurate internal estimate of self-movement is thought to emerge from sensorimotor integration; nonetheless, which circuits perform this internal estimation, and exactly how motor-sensory coordination is implemented within these circuits are basic questions that remain to be poorly understood. There is growing evidence suggesting that, during locomotion, motor-related and visual signals interact at early stages of visual processing. In mammals, however, it is not clear what the function of this interaction is. Recently, we have shown that a population of Drosophila optic-flow processing neurons —neurons that are sensitive to self-generated visual flow, receives convergent visual and walking-related signals to form a faithful representation of the fly’s walking movements. Leveraging from these results, and combining quantitative analysis of behavior with physiology, optogenetics, and modelling, we propose to investigate circuit mechanisms of self-movement estimation during walking. We will:1) use cell specific manipulations to identify what cells are necessary to generate the motor-related activity in the population of visual neurons, 2) record from the identified neurons and correlate their activity with specific locomotor parameters, and 3) perturb the activity of different cell-types within the identified circuits to test their role in the dynamics of the visual neurons, and on the fly’s walking behavior. These experiments will establish unprecedented causal relationships among neural activity, the formation of an internal representation, and locomotor control. The identified sensorimotor principles will establish a framework that can be tested in other scenarios or animal systems with implications both in health and disease.

1 500 000 €

Start date: 2017-11-01, End date: 2022-10-31

Cytokinesis completes cell division by partitioning the contents of the mother cell to the two daughter cells. This process is accomplished through the assembly and constriction of a contractile ring, a complex actomyosin network that remains poorly understood on the molecular level. Research in cytokinesis has overwhelmingly focused on signaling mechanisms that dictate when and where the contractile ring is assembled. By contrast, the research I propose here addresses fundamental questions about the structural and functional properties of the contractile ring itself. We will use the nematode C. elegans to exploit the power of quantitative live imaging assays in an experimentally tractable metazoan organism. The early C. elegans embryo is uniquely suited to the study of the contractile ring, as cells dividing perpendicularly to the imaging plane provide a full end-on view of the contractile ring throughout constriction. This greatly facilitates accurate measurements of constriction kinetics, ring width and thickness, and levels as well as dynamics of fluorescently-tagged contractile ring components. Combining image-based assays with powerful molecular replacement technology for structure-function studies, we will 1) determine the contribution of branched and non-branched actin filament populations to contractile ring formation; 2) explore its ultra-structural organization in collaboration with a world expert in electron microcopy; 3) investigate how the contractile ring network is dynamically remodeled during constriction with the help of a novel laser microsurgery assay that has uncovered a remarkably robust ring repair mechanism; and 4) use a targeted RNAi screen and phenotype profiling to identify new components of actomyosin contractile networks. The results from this interdisciplinary project will significantly enhance our mechanistic understanding of cytokinesis and other cellular processes that involve actomyosin-based contractility.

1 499 989 €

Start date: 2015-07-01, End date: 2021-12-31

Zinc finger (ZF) and transcription activator-like effector (TALE) based technologies are been allowing the tailored design of “artificial” DNA-binding proteins targeted to specific and unique DNA genomic sequences. Coupling DNA binding proteins to effectors domains enables the constitution of DNA binding factors for genomic directed transcriptional modulation or targeted genomic editing. We have demonstrated that pairing a ZF DNA binding protein to the transcriptional repressor Kruppel-associated box enables in vivo, the transcriptional repression of one of the most abundantly expressed gene in mammals, the human rhodopsin gene (RHO). We propose to generate RHO DNA binding silencers (“AlleleChoker”), which inactivate RHO either by transcriptional repression or targeted genome modification, irrespectively to wild-type or mutated alleles (mutational-independent approach), and combine RHO endogenous silencing to RHO replacement (silencing-replacement strategy). With this strategy in principle a single bimodal bio-therapeutic will enable the correction of any photoreceptor disease associated with RHO mutation. Adeno-associated viral (AAV) vector-based delivery will be used for photoreceptors gene transfer. Specifically our objectives are: 1) Construction of transcriptional repressors and nucleases for RHO silencing. Characterization and comparison of RHO silencing mediated by transcriptional repressors (ZFR/ TALER) or nucleases (ZFN/ TALEN) to generate genomic directed inactivation by non-homologous end-joining (NHEJ), and refer these results to RNA interference (RNAi) targeted to RHO; 2) RHO silencing in photoreceptors. to determine genome-wide DNA binding specificity of silencers, chromatin modifications and expression profile on human retinal explants; 3) Tuning silencing and replacement. To determine the impact of gene silencing-replacement strategy on disease progression in animal models of autosomal dominant retinitis pigmentosa (adRP) associated to RHO mutations

1 354 840 €

Start date: 2013-02-01, End date: 2018-01-31

Normal placental angiogenesis is critical for embryonic survival and development. Epigenetic modifications, such as methylation of CpG islands, regulate the expression and imprinting of genes. Epigenetic abnormalities have been observed in embryos from assisted reproductive technologies (ART), which could explain the poor placental vascularisation, embryonic/fetal death, and altered fetal growth in these pregnancies. Both cloned (somatic cell nuclear transfer, or SNCT) and monoparental (parthogenotes, only maternal genes; androgenotes, only paternal genes) embryos provide important models for studying defects in expression and methylation status/imprinting of genes regulating placental function. Our hypothesis is that placental vascular development is compromised during early pregnancy in embryos from ART, in part due to altered expression or imprinting/methylation status of specific genes regulating placental angiogenesis. We will evaluate fetal growth, placental vascular growth, and expression and epigenetic status of genes regulating placental angiogenesis during early pregnancy in 3 Specific Aims: (1) after natural mating; (2) after transfer of biparental embryos from in vitro fertilization, and SCNT; and (3) after transfer of parthenogenetic or androgenetic embryos. These studies will therefore contribute substantially to our understanding of the regulation of placental development and vascularisation during early pregnancy, and could pinpoint the mechanism contributing to embryonic loss and developmental abnormalities in foetuses from ART. Any or all of these observations will contribute to our understanding of and also our ability to successfully employ ART, which are becoming very wide spread and important in human medicine as well as in animal production.

363 600 €

Start date: 2008-10-01, End date: 2012-06-30