Figure 5.

The Cysteine Protease Inhibitor E-64 Blocks Psh-Dependent Induction of drs Expression upon Immune Challenge

(A–C) A total of 18.4 nL of PBS alone or containing 2 mM of the cysteine protease inhibitor E-64 were injected into w¹¹¹⁸ (WT), psh¹ (Psh), and Grass^hrd flies (Grass). spz^rm7 mutant flies (Spz) were used as control. After 2 hr, flies were immune challenged for 24 hr by septic injury with E. faecalis (OD₆₀₀ = 1) (A), by natural infection with B. bassiana (B), or by septic injury with M. luteus (OD₆₀₀ > 200) (C).

(D–F) The E-64 inhibitor was injected at 0.5 or 2 mM into w¹¹¹⁸ flies and Grass^hrd, psh¹, and spz^rm7 mutant flies were used as control. After 2 hr, flies were challenged for 16 hr with A. oryzae protease (D), for 24 hr with M. luteus peptidoglycans (E), and for 16 hr with B. subtilis protease (F). Flies were collected and drs gene expression was monitored by qRT-PCR in total RNA extracts. Ribosomal protein 49 (Rp49) mRNA was used as reference gene. Results were normalized to the value obtained with the control conditions.

Data represent means ± SEs of three independent experiments, each containing three groups of ten flies (five males and five females). p values obtained from Student’s t test are indicated on the graphs.