Genetic, structural, and chemical insights into the dual function of GRASP55 in germ cell Golgi remodeling and JAM-C polarized localization during spermatogenesis

Amandine Cartier-Michaud (1, 2) , Anne-Laure Bailly (1, 2) , Stéphane Betzi (2, 1) , Xiaoli Shi (1, 2) , Jean-Claude Lissitzky (1, 2) , Ana Zarubica (3, 1, 2) , Arnauld Sergé (1, 2) , Philippe Roche (2, 1) , Adrien Lugari (1, 2) , Véronique Hamon (1, 2) , Florence Bardin (1, 2) , Carine Derviaux (1, 2) , Frédérique Lembo (2, 1) , Stéphane Audebert (1, 2) , Sylvie Marchetto (2, 1) , Bénédicte Durand (1, 2) , Jean-Paul Borg (2, 1) , Ning Shi (1, 2) , Xavier Morelli (1, 2) , Michel Aurrand-Lions (1, 2)

1 IPC - Institut Paoli-Calmettes
2 CRCM - Centre de Recherche en Cancérologie de Marseille
3 CIML - Centre d'Immunologie de Marseille - Luminy

Spermatogenesis is a dynamic process that is regulated by adhesive interactions between germ and Sertoli cells. Germ cells express the Junctional Adhesion Molecule-C (JAM-C, encoded by Jam3), which localizes to germ/Sertoli cell contacts. JAM-C is involved in germ cell polarity and acrosome formation. Using a proteomic approach, we demonstrated that JAM-C interacted with the Golgi reassembly stacking protein of 55 kDa (GRASP55, encoded by Gorasp2) in developing germ cells. Generation and study of Gorasp2-/- mice revealed that knock-out mice suffered from spermatogenesis defects. Acrosome formation and polarized localization of JAM-C in spermatids were altered in Gorasp2-/- mice. In addition, Golgi morphology of spermatocytes was disturbed in Gorasp2-/- mice. Crystal structures of GRASP55 in complex with JAM-C or JAM-B revealed that GRASP55 interacted via PDZ-mediated interactions with JAMs and induced a conformational change in GRASP55 with respect of its free conformation. An in silico pharmacophore approach identified a chemical compound called Graspin that inhibited PDZ-mediated interactions of GRASP55 with JAMs. Treatment of mice with Graspin hampered the polarized localization of JAM-C in spermatids, induced the premature release of spermatids and affected the Golgi morphology of meiotic spermatocytes.

Mots clés: Spermatids; Seminiferous tubules; DAPI staining; Spermatocytes; Spermatogenesis; Testes; Germ cells; Acrosomes

Domaines: Sciences du Vivant [q-bio]; Biologie cellulaire

Amandine Cartier-Michaud, Anne-Laure Bailly, Stéphane Betzi, Xiaoli Shi, Jean-Claude Lissitzky, et al.. Genetic, structural, and chemical insights into the dual function of GRASP55 in germ cell Golgi remodeling and JAM-C polarized localization during spermatogenesis. PLoS Genetics, 2017, 13 (6), ⟨10.1371/journal.pgen.1006803⟩. ⟨hal-01542697⟩