Abstract

The fruit fly Drosophila melanogaster Toll signaling pathway has an evolutionarily conserved role in controlling immune responses. Whereas the microbial recognition mechanisms and the core signaling pathway leading to activation of the humoral immune response via the NF-κB transcription factors have been well established for many years, the mechanistic understanding of the effector functions at the molecular level is currently rapidly evolving. In this review, we discuss the current developments in elucidating the role of the Drosophila Toll signaling pathway in immunity. We discuss the emerging role of Toll in viral infections and sex-specific differences in immunity. Mainly, we focus on Toll pathway regulation, the effector molecules, and cellular immunity.

Footnotes

This work was supported by a Tampere Tuberculosis Foundation grant to S.V., by Academy of Finland Grant 32273 and Sigrid Jusélius Foundation Grant 3122800849 to T.S.S., and by Sigrid Jusélius Foundation Grant 220161 and a Tampere Tuberculosis Foundation grant to M.R. The Drosophila work was carried out in the Tampere Drosophila Facility, which is partly funded by Biocenter Finland.

Abbreviations used in this article:

AMPantimicrobial peptideBaraABaramicin ABomBomaninCactCactusDAMPdamage-associated molecular patternDCVDrosophila C virusDlDorsalDrsDrosomycinIBINInduced by InfectionIMimmune-induced moleculeird1immune response deficient 1JumuJumeaulncRNAlong noncoding RNAmiRNAmicroRNAPliPellinoPRRpattern recognition receptorPSCposterior signaling centerPsyPersephoneRNAiRNA interferenceROSreactive oxygen speciesS2Schneider 2SPESpz processing enzymeSpzSpatzleTEPthioester-containing proteinVSVvesicular stomatitis virusReceived June 30, 2022.Accepted August 16, 2022.Copyright © 2022 by The American Association of Immunologists, Inc.