A splice variant of PGRP‐LC required for expression of antimicrobial peptides in Anopheles gambiae

Abstract Members of the peptidoglycan recognition protein (PGRP) family play essential roles in different manifestations of immune responses in insects. PGRP‐LC, one of seven members of this family in the malaria vector Anopheles gambiae produced several spliced variants. Here we show that PGRP‐LC, and not other members of the PGRP family nor the six members of the Gram‐negative binding protein families, is required for the expression of antimicrobial peptide genes (such as CEC1 and GAM1) under the control of the Imd‐Rel2 pathway in an A. gambiae cell line, 4a3A. PGRP‐LC produces many splice variants that can be classified into three sub‐groups (LC1, LC2 and LC3), based on the carboxyl terminal sequences. RNA interference against one LC1 sub‐group resulted in dramatic reduction of CEC1 and GAM1. Over‐expression of LC1a and to a lesser extent LC3a (a member of the LC1 and LC3 sub‐group, respectively) in the 4a3A cell line enhances the expression of CEC1 and GAM1. These results demonstrate that the LC1‐subgroup splice variants are essential for the expression of CEC1 and GAM1 in A. gambiae cell line.