C. elegans Tensin Promotes Axon Regeneration by Linking the Met-like SVH-2 and Integrin Signaling Pathways.

Axon regeneration is a conserved mechanism induced by axon injury that initiates a neuronal response leading to regrowth of the axon. In Caenorhabditis elegans, the initiation of axon regeneration is regulated by the JNK MAP kinase (MAPK) pathway. We have previously identified a number of genes affecting the JNK pathway using an RNAi-based screen. Analysis of these genes, called the svh genes, has shed new light on the regulation of axon regeneration, revealing the involvement of a signaling cascade consisting of a growth factor SVH-1 and its receptor, the tyrosine kinase SVH-2. Here, we characterize the svh-6/tns-1 gene, which is a homolog of mammalian tensin, and show that it is a positive regulator of axon regeneration in motor neurons. We demonstrate that TNS-1 interacts with tyrosine-autophosphorylated SVH-2 and the integrin β subunit PAT-3 via its SH2 and PTB domains, respectively, to promote axon regeneration. These results suggest that TNS-1 acts as an adaptor to link the SVH-2 and integrin signaling pathways.SIGNIFICANCE STATEMENT The Caenorhabditis elegans JNK MAPK pathway regulates the initiation of axon regeneration. Previously, we showed that a signaling cascade consisting of the HGF-like growth factor SVH-1 and its Met-like receptor tyrosine kinase SVH-2 promotes axon regeneration through activation of the JNK pathway. In this study, we show that the C. elegans tensin, TNS-1, is required for efficient regeneration after axon injury. Phosphorylation of SVH-2 on tyrosine mediates its interaction with the SH2 domain of TNS-1 to positively regulate axon regeneration. Furthermore, TNS-1 interacts via its PTB domain with the integrin β subunit PAT-3. These results suggest that TNS-1 plays a critical role in the regulation of axon regeneration by linking the SVH-2 and integrin signaling pathways.