An RNA interference screen ide.jpgies Inhibitor of Apoptosis Protein 2 as a regulator of innate immune signalling in Drosophila

Abstract

Innate immunity in vertebrates and invertebrates is of central importance as a biological programme for host defence against pathogenic challenges. To find novel components of the Drosophila immune deficiency (IMD) pathway in cultured haemocyte-like cells, we screened an RNA interference library for modifiers of a pathway-specific reporter. Selected modifiers were further characterized using an independent reporter assay and placed into the pathway in relation to known pathway components. Interestingly, the screen identified the Inhibitor of Apoptosis Protein 2 (IAP2) as being required for IMD signalling. Whereas loss of DIAP1, the other member of the IAP protein family in Drosophila, leads to apoptosis, we show that IAP2 is dispensable for cell viability in haemocyte-like cells. Cell-based epistasis experiments show that IAP2 acts at the level of Tak1 (transforming growth factor-b-activated kinase 1

Methods to study Drosophila immunity

“…While the patchy efficiency of first generation RNAis relegated in vivo screens to fishing expeditions, improved second-generation RNAi libraries promise optimized throughput in RNAi-based screens. S2-based RNAi screens have successfully identified novel Toll, Imd and JNK pathway components [56][57][58][59], determinants of intracellular pathogen resistance [60] or phagocytic receptors on hemocytes [61,62], and in vivo RNAi screens have contributed to our understanding of Drosophila hemocyte development or response to intestinal infection [63,64].…”

Inhibitor of Apoptosis (IAP) Proteins-Modulators of Cell Death and Inflammation

“…NF-kB transcription factors are important regulators of the genes necessary for innate and adaptive immune responses and for the survival and proliferation of certain cell types (Karin and Greten 2005). The realization that IAPs function as critical components of NF-kB signal transduction first came from Drosophila where DIAP2 was found to be essential to fend off Gram-negative bacterial infection (Gesellchen et al 2005;Kleino et al 2005;Leulier et al 2006a;Huh et al 2007). In Drosophila, infection by Gram-negative bacteria triggers the innate immune response by activating the immune deficiency (IMD) signaling cascade (Lemaitre and Hoffmann 2007), a Rel/NF-kB-dependent pathway that shares striking similarities with mammalian tumor necrosis factor receptor 1 (TNF-R1) (Tanji and Ip 2005).…”

Relationship between [ 14 C]MeAIB uptake and amino acid transporter family gene expression levels or proliferative activity in a pilot study in human carcinoma cells: Comparison with [ 3 H]methionine uptake

“…Numerous amino acid transporters have been identified at the molecular level and have been characterized in mammalian cells [10][11][12]. The main transport systems for the uptake of neutral amino acids are the A, L, and alanine-serine-cysteine (ASC) amino acid transport systems.…”