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.

Inhibition of cystathionine β-synthase promotes apoptosis and reduces cell proliferation in chronic myeloid leukemia

Increased endogenous hydrogen sulfide(H_(2)S)level by cystathionine β-synthase(CBS)has been shown to closely relate tumorigenesis.H_(2)S promotes angiogenesis,stimulates bioenergy metabolism and inhibits selective phosphatases.However,the role of CBS and H_(2)S in chronic myeloid leukemia(CML)remains elusive.In this study,we found that CBS and H_(2)S levels were increased in the bone marrow mononuclear cells of pediatric CML patients,as well as in the CML-derived K562 cells and CBS expression levels were correlated with different disease phases.Inhibition of CBS reduced the proliferation of the CML primary bone marrow mononuclear cells and induced growth inhibition,apoptosis,cell cycle arrest,and migration suppression in K562 cells and tumor xenografts.The knockdown of CBS expression by shRNA and inhibiting CBS activity by AOAA decreased the endogenous H_(2)S levels,promoted mitochondrial-related apoptosis and inhibited the NF-xB-mediated gene expression.Our study suggests that inhibition of CBS induces cell apoptosis,as well as limits cell proliferation and migration,a potential target for the treatment of chronic myeloid leukemia.