Contactin-associated protein-like 2(CNTNAP2)mutations impair the essentialα-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 a-secretase and presenilindependent y-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 a-cleavage product C79 by ADAM10 is required for the subsequent y-secretase cleavage to generate CNTNAP2 intracellular domain(CICD).ASD-associated CNTNAP2 mutations impair the a-cleavage to generate C79,and the inhibition leads to ASDIlike repetitive and social behavior abnormalties in the Cntnap2l1254T knock-in mice.Finaly,exogenous expression of 79 improves autism-ike phenotypes in the Cntnap2^(11254T) knock-in and Cntnap2^(-/-)knockout mice.This data demonstrates that the a-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.