A novel Netrin-1–sensitive mechanism promotes local SNARE-mediated exocytosis during axon branching

Developmental axon branching dramatically increases synaptic capacity and neuronal surface area. Netrin-1 promotes branching and synaptogenesis, but the mechanism by which Netrin-1 stimulates plasma membrane expansion is unknown. We demonstrate that SNARE-mediated exocytosis is a prerequisite for axon branching and identify the E3 ubiquitin ligase TRIM9 as a critical catalytic link between Netrin-1 and exocytic SNARE machinery in murine cortical neurons. TRIM9 ligase activity promotes SNARE-mediated vesicle fusion and axon branching in a Netrin-dependent manner. We identified a direct interaction between TRIM9 and the Netrin-1 receptor DCC as well as a Netrin-1–sensitive interaction between TRIM9 and the SNARE component SNAP25. The interaction with SNAP25 negatively regulates SNARE-mediated exocytosis and axon branching in the absence of Netrin-1. Deletion of TRIM9 elevated exocytosis in vitro and increased axon branching in vitro and in vivo. Our data provide a novel model for the spatial regulation of axon branching by Netrin-1, in which localized plasma membrane expansion occurs via TRIM9-dependent regulation of SNARE-mediated vesicle fusion.     

The botany,uses and production ofWasabia japonica (Miq.) (Cruciferae) Matsum

Wasabi (Wasabia japonica) is a unique native plant and a traditional condiment crop of Japan. It is used in traditional Japanese raw fish and noodle dishes and in several modern foods for its hot taste and tangy flavor. Japanese farmers grow the crop in wet upland orchard soils for leaves, petioles and small enlarged stems, and in flooded gravel and sand fields along streams or near springs to produce whole plants and large succulent green enlarged stems. Recent studies in Japan have demonstrated numerous enzymatic and biocidal properties of the plant. This review of Japanese and other literature details the history, uses, botany, cultivars, ecological requirements, production techniques, insect pests and diseases of wasabi.