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4 juin 2021: 2 événements

  • Département Biologie des Génomes

    Vendredi 4 juin 10:00-11:00 - Arthur Talman - MIVEGEC (University of Montpellier-CNRS-IRD)

    Sex determination in malaria parasites

    Résumé : Malaria is caused by parasites of the genus Plasmodium. Whilst the disease is caused by asexual parasites, only sexual forms are capable of infecting mosquitoes. Sexual stages arise from a small subset of blood-stage parasites which divert from the cycle of asexual replication and embark on a sexual developmental trajectory. The bifurcation leading to a sexual fate is dependent on the master regulator of sex, the transcription factor AP2-G. In the absence of sex chromosomes or conserved sex-determining mechanisms, events that lead to determination into either a male or a female are completely unknown.
    We applied single cell technology to understand the cascade of transcriptional events leading to determination into one sex or the other in the rodent malaria parasite Plasmodium berghei. We performed a high throughput genome scale screen and identified genes involved in the sex determining pathway. We then characterised the role of one male determining factor in the human malaria parasite P. falciparum. We unravel the sex-specific regulation of md1 expression and initiate the functional characterisation of the sex determining pathway in human malaria parasites. Targeting sex determination to sterilise population of parasites in the host could be used as a strategy to interrupt transmission to mosquitoes.
    Contact : Joana SANTOS <joana.santos i2bc.paris-saclay.fr>

    En savoir plus : Département Biologie des Génomes
  • Département Biologie Cellulaire

    Vendredi 4 juin 11:00-12:00 - Aymeric BAILLY - CRBM Montpellier

    The Ubiquitin-like NEDD8 as a novel cellular stress signalling molecule.

    Résumé : Similarly to Ubiquitin, NEDD8 is activated and conjugated by a set of specialized enzymes (E1, E2 and E3) that covalently attach the NEDD8 molecule to its targets through a lysine residue. Although NEDD8 has been originally described for its role in regulating the Cullin-Ring-Ligase activities (CRL) through the modification of Cullins, recent advances established the existence of NEDD8 substrates beyond Cullins. Notably, we have found that NEDD8 can modify itself and form poly-NEDD8 chains that directly regulate HSP70 functions. I will present recent technological advances we have developped to identify novel NEDD8 E3 ligases.
    Contact : Renaud LEGOUIS <renaud.legouis i2bc.paris-saclay.fr>

    Lieu : Auditorium - bâtiment 21 - Gif ou visio

    En savoir plus : Département Biologie Cellulaire

4 juin 2021: 1 événement

  • Département Biologie Cellulaire

    Vendredi 4 juin 14:00-17:00 - thesis defense Romane LEBOUTET - team Legouis, I2BC

    Functions of ubiquitin-like proteins GABARAP/LGG-1 during autophagy and development in Caenorhabditis elegans by CRISPR-CAS9 engineering

    Résumé : Autophagy is an important recycling process for the maintenance of cell homeostasis, allowing the recycling of cytoplasmic components. This mechanism is conserved among eukaryotes. In mammals, six homologs of atg8 exist (LC3A, LC3B, LC3C, GABARAP, GABARAPL1, GABARAPL2) and have multiple roles during this process, in the initiation, the recognition of cargo, the closure of autophagosomes and the fusion with the lytic compartment. These proteins exist in several forms, the precursor (form P) is cleaved into a cytosolic protein (form I) which, via a lipid conjugation system, is localized to the membrane (form II). Our research focuses on LGG-1, the homologue of the GABARAP family, essential for the viability and the development of the nematode Caenorhabditis elegans. In order to determine the different roles of GABARAP/LGG-1, we generated mutants by CRISPR/ CAS9, allowing expression of only the precursor, only the mature cytosolic form, or both. We were able to show that glycine116 of LGG-1 is essential for an efficient precursor cleavage and the localization of LGG-1 to autophagosome membranes. Our results show that a non-lipidable form of LGG-1 is sufficient to maintain both selective autophagy during the development (mitophagy and aggregation), and the physiological global autophagy during aging, or induced following a nutritional stress. Our results suggest that the major function of the mature cleaved form is involved in the early induction stages of the process.

    Lieu : Auditorium - building 21 - Gif-sur-Yvette or videoconference

    En savoir plus : Département Biologie Cellulaire