BEGIN:VCALENDAR VERSION:2.0 PRODID:-//wp-events-plugin.com//6.4.7.2//EN TZID:Europe/Paris X-WR-TIMEZONE:Europe/Paris BEGIN:VEVENT UID:0-985@lptms.universite-paris-saclay.fr DTSTART;TZID=Europe/Paris:20241105T140000 DTEND;TZID=Europe/Paris:20241105T160000 DTSTAMP:20241017T083044Z URL:http://www.lptms.universite-paris-saclay.fr/seminars/soutenance-de-the se-enrico-lorenzetti/ SUMMARY:Soutenance de thèse: Enrico Lorenzetti - LPTMS (100% online semina r) - 5 Nov 24 14:00 DESCRIPTION:Modelling And Data Analysis of Protein Dynamics applied to a Fi ssion Yeast Mechanosensor\n \;\nEnrico Lorenzetti (Ladhyx\, LPTMS)\n&n bsp\;\n\nIntracellular dynamics is fundamental for cells to maintain homeo stasis and respond to environmental stimuli. Among these\, mechanical forc es can be a potential source of damage as they can compromise the integrit y of the cell. To cope with this risk\, living organisms are endowed with mechanosensors\, i.e. receptor at the sub-cellular level able to trigger a biological pathway by a mechanical signal. In fission yeast\, a mechanose nsor\, Wsc1 protein\, perceives excessive stress on the the cell wall and activates the glucan synthesis to keep this layer reinforced. More interes tingly\, Wsc1 concentration in- creases in the compressed region of the ce ll wall for- ming clusters. This work investigates this mechanosensitive c lustering behaviour advancing models and inference method for\nexperimenta l data of protein dynamics.\nBy setting a mathematical framework based on deterministic partial differential equations\, I describe the Wsc1 dynamic s along the cell wall. In this model\, I consider two possible protein rec ruitment mechanisms for shaping clusters\, either from the sides due to di ffusion along the cell wall and from the cytoplasm by exocytotosis. Moreov er\, following chemical considerations\, I suppose an affinity\nbetween th e cell wall and the protein that increases with the cell wall com- pressio n. The resulting reaction-diffusion equations obtained by this model are a ble to reproduce the clustering behaviour after cell wall compression. In addition\, the model correctly predicts a longer time-scale of the dynamic s in the compressed region of the cell wall. This result is in agreement w ith the outcomes of FRAP (Fluorescence Recovery After Photobleaching) expe riment\, whose analysis is based on the study of time-lapse images that re flects the spatial-temporal concentration of the molecule. However\, it is not clear yet if the protein recruitment is due to diffusion\, exchange w ith cytoplasm\, or both. For this reason\, in my work I also develop a new inference method for FRAP experiment capable of discerning different type s of dynamics. My analysis aims at quantifying the dynamical parameters\, such as diffusion coefficient and exchange rate\, by minimising the distan ce between the reaction-diffusion model prediction and actual data. The sp ecificity of my approach is the use of dimensional reduction to efficientl y perform computation without having knowledge of the initial bleached pro file. This new method is then tested and validated on artificial data. The results show that this analysis is flexible since it can work with imperf ect data\, where the signal-to-noise ratio is low\, the number of frames i s reduced and the spatial window is restricted.\nMoreover\, this approach can be potentially generalised to complex geometries\, for instance curved surface. This versatility is wellsuited for studying protein dynamics in the fission yeast cell wall. The inference method is applied to experiment al data of another mechanosensor in the cell wall\, Mtl2\, yielding reason able values of diffusion coefficient. Nevertheless\, it still needs to be tested on real\ndata of Wsc1 protein.\nOverall\, this study offers novel m ethodologies for quantifying and understanding intricate protein dynamics within cells and tissues.\n\nLocalization: amphithéâtre Becquerel - Éco le Polytechnique. CATEGORIES:seminars LOCATION:LPTMS (100% online seminar)\, LPTMS - Bâtiment Pascal n° 530 rue André Rivière - Université Paris-Saclay\, Orsay\, 91405\, France X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=LPTMS - Bâtiment Pascal n ° 530 rue André Rivière - Université Paris-Saclay\, Orsay\, 91405\, Fr ance;X-APPLE-RADIUS=100;X-TITLE=LPTMS (100% online seminar):geo:0,0 END:VEVENT BEGIN:VTIMEZONE TZID:Europe/Paris X-LIC-LOCATION:Europe/Paris BEGIN:STANDARD DTSTART:20241027T020000 TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET END:STANDARD END:VTIMEZONE END:VCALENDAR