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The interactome of the microcephaly gene ASPM in human cortical cells

par Piumatti, Matteo
Président du jury Casimir, Georges
Promoteur Vanderhaeghen, Pierre
Publication Non publié, 2021-05-18

Thèse de doctorat

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Résumé :

Mutations in the Abnormal Spindle-like Microcephaly-associated (ASPM) gene are the most common cause of primary microcephaly, a rare condition characterized by a severe reduction of brain size at birth. Several studies allowed to identify ASPM as a centrosome and mitotic spindle protein that regulates cell division and spindle orientation. However, little is known about ASPM molecular mechanisms, especially in human neural cells relevant to the disease. In order to decipher the molecular mechanisms of action of ASPM in human corticogenesis, we used co-immunoprecipitation (coIP) followed by mass spectrometry to identify the interactors of ASPM in human HEK cells and human cortical progenitors differentiated from pluripotent stem cells engineered to tag the endogenous ASPM protein. We thus identified and validated 14 ASPM interactors of which 12 are newly reported, and seven are found specifically in neural cells, including the important spindle pole regulator Nuclear mitotic apparatus (NUMA). We then characterized the expression and localization of the identified proteins in human cortical progenitors differentiated from control and isogenic ASPM mutant cells. This revealed that many of the identified proteins are selectively located at the spindle pole, and that this selective localization is disrupted in mutant cells for several of the interactors, in particular the MAP7 domain-containing protein 1 (MAP7D1) and DnaJ homolog subfamily B member 6 (DNAJB6). Our data uncover some of the complex ASPM interactome relevant and specific to human brain development and microcephaly, and suggest that ASPM acts as a major molecular hub at the centrosome and mitotic spindle to control the patterns of cell division of cortical progenitors.