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13 novembre 2020: 1 événement

  • Département Biologie des Génomes

    Vendredi 13 novembre 11:00-12:00 - Ines DRINNENBERG - Institut Curie, Paris

    Evolution of centromeres : Conserved functions but diverse architectures

    Résumé : Despite their essentiality for faithful chromosome segregation, centromere architectures are diverse among eukaryotes and embody two main configurations : mono- and holocentromeres, referring respectively to a localized or unrestricted distribution of centromeric activity. Previous studies revealed that holocentricity in many insects strongly coincides with the loss of the otherwise essential centromeric marker CenH3 (CENP-A), suggesting a molecular link between the two events.
    Here, we aim to characterize this unique CenH3-deficient chromosome segregation pathway. Using proteomic and genomic approaches in Bombyx mori (silk moth) cell lines, we aim to determine the mechanism of CenH3-independent kinetochore assembly that led to the establishment of their holocentric architecture.
    In this context, we have recently identified additional inner kinetochore components including CENP-T and determined their contribution to kinetochore assembly independent of CenH3. In addition, we also leveraged the identification of these kinetochore components against which we also generated antibodies to map and characterize the centromeres of B. mori. This uncovered a robust correlation between centromere profiles and regions of low chromatin dynamics found anywhere along the chromosome. Transcriptional perturbation experiments showed that centromeres become excluded from regions of active chromatin but can form de novo in regions where chromatin activity is low. The identified link to chromatin dynamics helps to discuss the plasticity of centromere identity. In this context, our study points to a novel mechanism of centromere formation that occurs in a manner recessive to the chromosome-wide chromatin landscape rather than being defined by the presence of CenH3. Based on similar profiles observed in additional Lepidoptera, we propose an evolutionarily conserved mechanism that underlies the establishment of holocentromeres through loss of a specified centromere.

    Contact : Daan NOORDERMEER <daan.noordermeer i2bc.paris-saclay.fr>

    Lieu : Auditorium - bâtiment 21 - campus de Gif-sur-Yvette

    En savoir plus : Département Biologie des Génomes