Identification of cancer-associated missense mutations in hace1 that impair cell growth control and Rac1 ubiquitylation

Emilie Andrio (1, 2) , Romain Lotte (1, 2, 3) , Daniel Hamaoui (1, 2) , Jacqueline Cherfils (4) , Anne Doye (2, 1) , Mads Daugaard (5, 6) , Poul Sørensen (7) , Frédéric Bost (8, 1) , Raymond Ruimy (1, 2, 3) , Amel Mettouchi (1, 2) , Emmanuel Lemichez (2, 1)

1 C3M - Centre méditerranéen de médecine moléculaire
2 Toxines bactériennes dans la relation hôtes-pathogènes
3 Laboratoire de Bactériologie [CHU Nice]
4 LBPA - Laboratoire de Biologie et de Pharmacologie Appliquée
5 UBC - University of British Columbia
6 VPC - Vancouver Prostate Centre [Vancouver General Hospital]
7 BCCRC - BC Cancer Agency Research Centre
8 Signalisation moléculaire et obésité

The E3 ubiquitin ligase HACE1 is a potent tumor suppressor that controls cell proliferation and ubiquitylates the small GTPase Rac1 to target it to proteasomal degradation. Whether and how the activity of HACE1 is regulated by the N-terminal ankyrin (ANK) and the middle (MID) domains is ill defined. Here, we identified in the version 64 of the Catalogue of Somatic Mutations in Cancer (COSMIC) 13 missense mutations of hace1 located outside the HECT domain, and found that all lead to defective control of cell proliferation. In addition, several mutations located in the ankyrin domain displayed a dramatic reduction in Rac1 ubiquitylation associated with a decrease of colony formation in soft agar. 3D structure modelling of the 7 ankyrin-repeats coupled to functional analysis identified a surface epitope centered on one of the mutated residue, Gly-175, which is critical for controlling Rac1 binding and ubiquitylation. We also identified a role for the MID domain in conferring the specificity of association of HACE1 to the active form of Rac1. Our study of the functional interplay between HACE1 and Rac1 in cancer thus sheds a new light on the molecular mechanism of Rac1 ubiquitylation by HACE1 and the impact of its cancer-associated mutations in cell proliferation.

Keywords: Proteolysis; Cell biology

Domains: Life Sciences [q-bio]; Microbiology and Parasitology; Bacteriology; Cellular Biology; Subcellular Processes [q-bio.SC]; Cell Behavior [q-bio.CB]

Emilie Andrio, Romain Lotte, Daniel Hamaoui, Jacqueline Cherfils, Anne Doye, et al.. Identification of cancer-associated missense mutations in hace1 that impair cell growth control and Rac1 ubiquitylation. Scientific Reports, 2017, 7 (1), pp.44779. ⟨10.1038/srep44779⟩. ⟨pasteur-02448600⟩