Contactin-associated protein-like 2 (CNTNAP2) mutations impair the essential -secretase cleavages, leading to autism-like phenotypes

Mutations in the Contactin-associated protein-like 2 (CNTNAP2) gene are associated with autism spectrum disorder (ASD), and ectodomain shedding of the CNTNAP2 protein plays a role in its function. However, key enzymes involved in the C-terminal cleavage of CNTNAP2 remain largely unknown, and the effect of ASD-associated mutations on this process and its role in ASD pathogenesis remain elusive. In this report we showed that CNTNAP2 undergoes sequential cleavages by furin, ADAM10/17-dependent alpha-secretase and presenilin-dependent gamma-secretase. We identified that the cleavage sites of ADAM10 and ADAM17 in CNTNAP2 locate at its C-terminal residue I79 and L96, and the main alpha-cleavage product C79 by ADAM10 is required for the subsequent gamma-secretase cleavage to generate CNTNAP2 intracellular domain (CICD). ASD-associated CNTNAP2 mutations impair the alpha-cleavage to generate C79, and the inhibition leads to ASD-like repetitive and social behavior abnormalities in the Cntnap2-I1254T knock-in mice. Finally, exogenous expression of C79 improves autism-like phenotypes in the Cntnap2(-I1254T) knock-in and Cntnap2(-/- )knockout mice. This data demonstrates that the alpha-secretase is essential for CNTNAP2 processing and its function. Our study indicates that inhibition of the cleavage by pathogenic mutations underlies ASD pathogenesis, and upregulation of its C-terminal fragments could have therapeutical potentials for ASD treatment.