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

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 ide.jpgied 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‐β‐activated kinase 1). Our results indicate that IAP gene family members may have acquired other functions, such as the regulation of the tumour necrosis factor‐like IMD pathway during innate immune responses.

[1]  M Vingron,et al.  An integrated gene annotation and transcriptional profiling approach towards the full gene content of the Drosophila genome , 2003, Genome Biology.

[2]  B. Hay,et al.  The Drosophila DIAP1 Protein Is Required to Prevent Accumulation of a Continuously Generated, Processed Form of the Apical Caspase DRONC* , 2002, The Journal of Biological Chemistry.

[3]  T. Maniatis,et al.  The Role of Ubiquitination in Drosophila Innate Immunity* , 2005, Journal of Biological Chemistry.

[4]  M. Levine,et al.  Immunity regulatory DNAs share common organizational features in Drosophila. , 2004, Molecular cell.

[5]  Gerald M. Rubin,et al.  Drosophila homologs of baculovirus inhibitor of apoptosis proteins function to block cell death , 1995, Cell.

[6]  G. Hannon,et al.  Unlocking the potential of the human genome with RNA interference , 2004, Nature.

[7]  J. Hoffmann,et al.  Drosophila innate immunity: an evolutionary perspective , 2002, Nature Immunology.

[8]  N. Perrimon,et al.  Genome-Wide RNAi Analysis of Growth and Viability in Drosophila Cells , 2004, Science.

[9]  Norbert Perrimon,et al.  Signaling role of hemocytes in Drosophila JAK/STAT-dependent response to septic injury. , 2003, Developmental cell.

[10]  Zhijian J. Chen,et al.  TAK1 is a ubiquitin-dependent kinase of MKK and IKK , 2001, Nature.

[11]  A. Fire,et al.  Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans , 1998, Nature.

[12]  K. Irie,et al.  TAB1: an activator of the TAK1 MAPKKK in TGF-beta signal transduction. , 1996, Science.

[13]  David L. Vaux,et al.  IAPs, RINGs and ubiquitylation , 2005, Nature Reviews Molecular Cell Biology.

[14]  B. Lemaître,et al.  How Drosophila combats microbial infection: a model to study innate immunity and host-pathogen interactions. , 2002, Current opinion in microbiology.

[15]  G. Rubin,et al.  A putative Ras GTPase activating protein acts as a negative regulator of signaling by the Sevenless receptor tyrosine kinase , 1992, Cell.

[16]  Michael Boutros,et al.  Identification of JAK/STAT signalling components by genome-wide RNA interference , 2005, Nature.

[17]  G. Evan,et al.  The Drosophila caspase DRONC is regulated by DIAP1 , 2000, The EMBO journal.

[18]  J. Hoffmann,et al.  The immune response of Drosophila , 2003, Nature.

[19]  K. Irie,et al.  TAB1: An Activator of the TAK1 MAPKKK in TGF-β Signal Transduction , 1996, Science.

[20]  Tom Maniatis,et al.  Caspase-mediated processing of the Drosophila NF-κB factor Relish , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[21]  D. Zachary,et al.  Drosophila immune deficiency (IMD) is a death domain protein that activates antibacterial defense and can promote apoptosis. , 2001, Developmental cell.

[22]  K. Irie,et al.  TAB2, a novel adaptor protein, mediates activation of TAK1 MAPKKK by linking TAK1 to TRAF6 in the IL-1 signal transduction pathway. , 2000, Molecular cell.

[23]  R. Kind,et al.  The Nature of the 660-Kilometer Upper-Mantle Seismic Discontinuity from Precursors to the PP Phase , 1996, Science.

[24]  N. Perrimon,et al.  Sequential activation of signaling pathways during innate immune responses in Drosophila. , 2002, Developmental cell.

[25]  J C Reed,et al.  IAP family proteins--suppressors of apoptosis. , 1999, Genes & development.

[26]  S. Orkin,et al.  The Friend of GATA proteins U-shaped, FOG-1, and FOG-2 function as negative regulators of blood, heart, and eye development in Drosophila , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[27]  D. Hultmark,et al.  In vitro induction of cecropin genes--an immune response in a Drosophila blood cell line. , 1992, Biochemical and biophysical research communications.

[28]  J. Hoffmann,et al.  The Jak-STAT signaling pathway is required but not sufficient for the antiviral response of drosophila , 2005, Nature Immunology.

[29]  Akira Ishizuka,et al.  Distinct roles for Argonaute proteins in small RNA-directed RNA cleavage pathways. , 2004, Genes & development.

[30]  J. Hoffmann,et al.  Toll-related receptors and the control of antimicrobial peptide expression in Drosophila. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[31]  K. Anderson,et al.  Drosophila: the genetics of innate immune recognition and response. , 2004, Annual review of immunology.