Different flavors of Toll guide olfaction

The ECSIT Mediated Toll3-Dorsal-ALFs Pathway Inhibits Bacterial Amplification in Kuruma Shrimp

The Toll signaling pathway plays an important role in animal innate immunity. However, its activation and signal transmission greatly differ across species and need to be investigated. Shrimp farming is a worldwide economic activity affected by bacterial disease from the 1990s, which promoted research on shrimp immunity. In this study, we first proved that, among the three identified Toll receptors in Marsupenaeus japonicus kuruma shrimp, Toll 3 plays a pivotal role in initiating the antibacterial response in vivo, especially upon anti-Staphylococcus aureus infection. Further research showed that this result was due to the activation of the Dorsal transcription factor, which induced the expression of two anti-lipopolysaccharide factors (Alfs). Moreover, the evolutionarily conserved signaling intermediate in Toll pathways, ECSIT, was proved to be needed for signal transmission from Toll 3 to Dorsal and the expression of anti-lipopolysaccharide factors. Finally, the mortality assay showed that a Toll3-ECSIT-Dorsal-Alf axis was functional in the anti-S.aureus immunity of M. japonicus shrimp. The results provide new insights into the function and signal transduction of the Toll pathway in aquatic species and offer basic knowledge for shrimp disease control and genetic breeding.

Characterization of Spz5 as a novel ligand for Drosophila Toll-1 receptor

The Drosophila Toll-1 receptor is involved in embryonic development, innate immunity, and tissue homeostasis. Currently, as a ligand for the Toll-1 receptor, only Spätzle (Spz) has been identified and characterized. We previously reported that Drosophila larva-derived tissue extract contains ligand activity for the Toll-1 receptor, which differs from Spz based on the observation that larval extract prepared from spz mutants possessed full ligand activity. Here, we demonstrate that Spz5, a member of the Spz family of proteins, functions as a ligand for the Toll-1 receptor. Processing of Spz5 by Furin protease, which is known to be important for ligand activity of Spz5 to Toll-6, is not required for its function to the Toll-1 receptor. By generating a spz5 null mutant, we further showed that the Toll-1 ligand activity of larva-derived extract is mainly derived from Spz5. Finally, we found a genetic interaction between spz and spz5 in terms of developmental processes. This study identified a novel ligand for the Drosophila Toll-1 receptor, providing evidence that Toll-1 is a multi-ligand receptor, similar to the mammalian Toll-like receptor.