No evidence that human GIGYF2 interacts with growth factor receptor-bound protein 10 (GRB10): implication for human disease

GIGYF2 (Growth factor receptor bound protein 10 (GRB10)-interacting GYF (glycine-tyrosine-phenylalanine) protein 2) reduces mRNA stability and translation via microRNAs, ribosome quality control, and several RNA-binding proteins. GIGYF2 was first identified in mouse cell lines as an interacting partner with Growth factor receptor-bound protein 10 (GRB10), which binds to the insulin receptor and insulin-like growth-factor receptor 1. Mutations in the human GIGYF2 gene were reported in autism spectrum disorder and Parkinsons disease. In mouse models, mutations in the gene encoding GIGYF2 exhibited disease phenotypes. It was, therefore, thought that the GIGYF2-associated disease in humans is caused by defective GRB10 signaling. We show here that GIGYF2 does not interact with GRB10 in human cell lines, as determined by proximity ligation and co-immunoprecipitation assays. Size exclusion chromatography assay further confirmed these findings. The lack of interaction is explained by the absence of the critical GYF-domain binding PPG{Phi} sequence in the human GRB10 protein. These results are in contrast with the current understanding that a GIGYF2/GRB10 complex is associated with human disease via IR and IGF-1R signaling and underscore alternative mechanisms responsible for the observed phenotypes related to mutations in the human GIGYF2 gene.