Filopodia-like protrusions of adjacent somatic cells shape the developmental potential of oocytes

Authors:

Flora Crozet, Gaëlle Letort, Rose Bulteau, Christelle Da Silva, Adrien Eichmuller, Anna Francesca Tortorelli, Joséphine Blévinal, Morgane Belle, Julien Dumont, Tristan Piolot, Aurélien Dauphin, Fanny Coulpier, Alain Chédotal, Jean-Léon Maître, Marie-Hélène Verlhac, Hugh J Clarke, Marie-Emilie Terret

Keywords:

Oocytes, Filipodia

Abstract:

The oocyte must grow and mature before fertilization, thanks to a close dialogue with the somatic cells that surround it. Part of this communication is through filopodia-like protrusions, called transzonal projections (TZPs), sent by the somatic cells to the oocyte membrane. To investigate the contribution of TZPs to oocyte quality, we impaired their structure by generating a full knockout mouse of the TZP structural component myosin-X (MYO10). Using spinning disk and super-resolution microscopy combined with a machine-learning approach to phenotype oocyte morphology, we show that the lack of Myo10 decreases TZP density during oocyte growth. Reduction in TZPs does not prevent oocyte growth but impairs oocyte-matrix integrity. Importantly, we reveal by transcriptomic analysis that gene expression is altered in TZP-deprived oocytes and that oocyte maturation and subsequent early embryonic development are partially affected, effectively reducing mouse fertility. We propose that TZPs play a role in the structural integrity of the germline-somatic complex, which is essential for regulating gene expression in the oocyte and thus its developmental potential.

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