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.

Mussel-inspired agarose hydrogel scaffolds for skin tissue engineering

Polysaccharide hydrogels are widely used in tissue engineering because of their superior biocompatibility and low immunogenicity.However,many of these hydrogels are unrealistic for practical applications as the cost of raw materials is high,and the fabrication steps are tedious.This study focuses on the facile fabrication and optimization of agarose-polydopamine hydrogel(APG)scaffolds for skin wound healing.The first study objective was to evaluate the effects of polydopamine(PDA)on the mechanical properties,water holding capacity and cell adhesiveness of APG.We observed that APG showed decreased rigidity and increased water content with the addition of PDA.Most importantly,decreased rigidity translated into significant increase in cell adhesiveness.Next,the slow biodegradability and high biocompatibility of APG with the highest PDA content(APG3)was confirmed.In addition,APG3 promoted full-thickness skin defect healing by accelerating collagen deposition and promoting angiogenesis.Altogether,we have developed a straightforward and efficient strategy to construct functional APG scaffold for skin tissue engineering,which has translation potentials in clinical practice.

Synthesis of Polypeptides with High-Fidelity Terminal Functionalities under NCA Monomer-Starved Conditions

Controlled polypeptide synthesis viaα-amino acid N-carboxylic anhydride(NCA)polymerization using conventional primary amine initiators encounters two major obstacles:(i)normal amine mechanism(NAM)and activated monomer mechanism(AMM)coexist due to amine basicity and nucleophilicity and(ii)NCA is notoriously sensitive towards moisture and heat and unstable upon storage.We serendipitously discover that N-phenoxycarbonyl-functionalizedα-amino acid(NPCA),a latent NCA precursor,could be polymerized solely based on NAM with high initiating efficiency by using primary amine hydrochloride as an initiator.The polymerization affords well-defined polypeptides with narrow polydispersity and highfidelity terminal functionalities,as revealed by the clean set of MALDI-TOF MS patterns.We further demonstrate successful syntheses of random and block copolypeptides,even under open-vessel conditions.Overall,the integration of moistureinsensitive and air-tolerant NPCA precursors with stable primary amine hydrochloride initiators represents a general strategy for controlled synthesis of high-fidelity polypeptides with sophisticated functions.

Synthesis of Polypeptides with High-Fidelity Terminal Functionalities under NCA Monomer-Starved Conditions

Controlled polypeptide synthesis viaα-amino acid N-carboxylic anhydride(NCA)polymerization using conventional primary amine initiators encounters two major obstacles:(i)normal amine mechanism(NAM)and activated monomer mechanism(AMM)coexist due to amine basicity and nucleophilicity and(ii)NCA is notoriously sensitive towards moisture and heat and unstable upon storage.We serendipitously discover that N-phenoxycarbonyl-functionalizedα-amino acid(NPCA),a latent NCA precursor,could be polymerized solely based on NAM with high initiating efficiency by using primary amine hydrochloride as an initiator.The polymerization affords well-defined polypeptides with narrow polydispersity and highfidelity terminal functionalities,as revealed by the clean set of MALDI-TOF MS patterns.We further demonstrate successful syntheses of random and block copolypeptides,even under open-vessel conditions.Overall,the integration of moistureinsensitive and air-tolerant NPCA precursors with stable primary amine hydrochloride initiators represents a general strategy for controlled synthesis of high-fidelity polypeptides with sophisticated functions.

A General Strategy toward Synthesis of Well-Defined Polypeptides with Complex Chain Topologies

The precise synthesis of polypeptides with varying chain topologies has attracted significant interest due to their diverse functional applications.However,conventional polymerization of environment-susceptible N-carboxylic anhydride monomers using primary amine initiators suffers from inevitable side reactions,which greatly compromise chain-end fidelity,thereby disabling access to polypeptides with high-order architectures.Herein,we have developed a general and robust strategy based on normal aminemechanism for the synthesis of various topological polypeptides via polymerization of moisture-insensitive and airtolerant N-phenoxycarbonyl-functionalizedα-amino acid precursors using primary amine hydrochloride as initiators.This strategy enabled the synthesis of a block,star,star-block,brush-type,and multiblock(co)polypeptides with desired sequences,predictable molecular weights,low polydispersity,and high-fidelity chain ends even under open-air conditions.Remarkably,the robustness of this approach has been exemplified by the precise synthesis of welldefined photoresponsive decablock copolypeptides,exhibiting a spontaneous morphological evolution from polymersomes to lamellae nanostructures upon light irradiation.This work provides a general and reliable tool for synthesizing polypeptides with varying topologies,shedding light on the development of synthetic polypeptide-based materials.