Functional characterization of PGRP-LC1 of Anopheles gambiae through deletion and RNA interference

Abstract

Peptidoglycan recognition proteins (PGRP) play an important role in innate immunity in insects through the activation of the Imd pathway, which has been shown to be required in the antibacterial response in insects and in the limitation of the number of Plasmodium berghei oocysts developing in mosquito midgut. The LC1 gene of the PRGP family in Anopheles gambiae produces many products through alternative splicing. In this work, we demonstrate that PGRP-LC1a alone is sufficient to activate the Imd pathway in the A. gambiae L3-5 cell line through a combination of terminal or internal deletions, and RNA interference against endogenous PGRP-LC products. In the absence of endogenous PGRP-LC proteins, the integrity of the cytoplasmic domain is necessary for LC1a function, while that of the extracellular domain is not. Moreover, the shorter the extracellular domain, the higher the activity for LC1a. However, the removal of either the cytoplasmic or the extracellular PGRP-binding domain has little impact on the activity of LC1a in the presence of endogenous PGRP-LC proteins. © Institute of Zoology, Chinese Academy of Sciences.