Labex Memolife IBENS • CIRB • Laboratoire Plasticité du Cerveau de l'ESPCI

Samuel Tozer, Chooyoung Baek, Evelyne Fischer, Rosette Goiame and Xavier Morin

Highlights
• Centriolar satellites constitute a docking point for Mib1 at the daughter centriole
• Mib1 is inherited by the prospective neuron following asymmetric divisions
• Mib1 asymmetry regulates fate choices through unequal Notch activation in daughter cells
• In proliferative divisions, a Golgi apparatus pool of Mib1 compensates for the asymmetry

Summary
Unequal centrosome maturation correlates with asymmetric division in multiple cell types. Nevertheless, centrosomal fate determinants have yet to be identified. Here, we show that the Notch pathway regulator Mindbomb1 co-localizes asymmetrically with centriolar satellite proteins PCM1 and AZI1 at the daughter centriole in interphase. Remarkably, while PCM1 and AZI1 remain asymmetric during mitosis, Mindbomb1 is associated with either one or both spindle poles. Asymmetric Mindbomb1 correlates with neurogenic divisions and Mindbomb1 is inherited by the prospective neuron. By contrast, in proliferative divisions, a supplementary pool of Mindbomb1 associated with the Golgi apparatus in interphase is released during mitosis and compensates for Mindbomb1 centrosomal asymmetry. Finally, we show that preventing Mindbomb1 centrosomal association induces reciprocal Notch activation between sister cells and promotes symmetric divisions. Thus, we uncover a link between differential centrosome maturation and Notch signaling and reveal an unexpected compensatory mechanism involving the Golgi apparatus in restoring symmetry in proliferative divisions.

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