Developmental and Comparative Immunology 35 (2011) 521–524 Contents lists available at ScienceDirect Developmental and Comparative Immunology journal homepage: www.elsevier.com/locate/dci Short communication Mode of bacterial pathogenesis determines phenotype in elt-2 and elt-7 RNAi Caenorhabditis elegans Samantha L. Elliott ∗ , Craig R. Sturgeon 1 , Deborah M. Travers, Madeline C. Montgomery Department of Biology, St. Mary’s College of Maryland, 18952 East Fisher Road, St. Mary’s City, MD 20686, USA article info Article history: Received 15 November 2010 Received in revised form 9 December 2010 Accepted 11 December 2010 Available online 17 December 2010 Keywords: Caenorhabditis elegans Pseudomonas aeruginosa Immunity GATA transcription factors abstract Caenorhabditis elegans has become a useful model for studying innate immunity. ELT-2, which is homol- ogous to human GATA-4, -5 and -6, is considered the primary GATA transcription factor controlling intestinal immunity in C. elegans. In this study, we characterize the timeline of intestinal distension in nematodes where ELT-2 and another intestinal GATA transcription factor, ELT-7, are abrogated by RNAi using two different models: colonization and toxin-based infections by Pseudomonas aeruginosa. We show that both ELT-2 and ELT-7 are important for survival of C. elegans exposed to P. aeruginosa. Intestinal distension is accelerated in elt-2 RNAi nematodes, and is observed in colonization but not toxin-based Pseudomonas infection. Upon onset of intestinal distension, nematodes die within 24 h, regardless of experimental treatment. These data provide new insight into the role of ELT-2 and ELT-7 in protecting C. elegans against P. aeruginosa infection. © 2010 Elsevier Ltd. All rights reserved. 1. Introduction Over the last decade, Caenorhabditis elegans has become a model organism for understanding innate immunity (reviewed in Irazoqui et al., 2010b). Many evolutionarily conserved signaling pathways are present in C. elegans and play a role in the nema- tode immune response, including the MAPK, TGF-, programmed cell death, and insulin-like DAF-2/DAF-16 pathways (reviewed in Shivers et al., 2008). However, regulation of the C. elegans immune system remains largely unknown. DAF-16 itself is a transcription factor which, along with its negative regulator DAF-2, controls both nematode aging and portions of the immune response (Alper et al., 2010). The ATF-7 transcription factor has been recently linked to regulation of C. elegans immunity through the p38 MAPK pathway (Shivers et al., 2010). ZIP-2 is a transcription factor recently associ- ated with the C. elegans immune response to Pseudomonas through regulation of irg-2 (Estes et al., 2010). Previous work has impli- cated ELT-2 as a transcriptional regulator of the nematode immune response to Gram positive, Gram negative and fungal pathogens. This role for ELT-2 is conserved in the human immune response to Pseudomonas aeruginosa (Kerry et al., 2006; Shapira et al., 2006). Abbreviations: RNAi, RNA interference; SK, “slow killing” or colonization media; PGS, “peptone–glucose–sorbitol” or toxin media; PA14-GFP, Pseudomonas aeruginosa expressing green fluorescent protein. ∗ Corresponding author. Tel.: +1 240 895 4376; fax: +1 240 895 4776. E-mail address: slelliott@smcm.edu (S.L. Elliott). 1 Present address: Center for Celiac and Mucosal Biology Research, University of Maryland School of Medicine, 655 W Baltimore Street, BRB 13-024, Baltimore, MD 21201, USA. Many of the ELT family of GATA transcription factors are expressed at the primary sites where nematodes interact with pathogens. ELT-3, -5 and -6 are expressed in the hypodermis (Koh and Rothman, 2001; Budovskaya et al., 2008). Of these, only ELT-3 has been implicated so far in the immune response to the fungus Drechmeria coniospora (Pujol et al., 2008). ELT-2, -4 and -7 are found in the C. elegans intestine (Fukushige et al., 2003; Hunt-Newbury et al., 2007). ELT-2 is the most well characterized of this family, and is considered the primary regulator of intestinal gene expres- sion, from embryonic development through adulthood (McGhee et al., 2007, 2009). Indeed, lack of ELT-2 expression causes devel- oping nematodes to arrest and die at the L1 larval stage (Fukushige et al., 1998). There is no documented role for ELT-4 and ELT-7 in the nematode immune response; ELT-4 is considered a small, redun- dant gene in intestinal development, and ELT-7 has no direct effect on survival of nematodes on S. enterica (Fukushige et al., 2003; Kerry et al., 2006). Similarly to ELT-2, ELT-7 appears to play a role in C. elegans development, though this role is not as pronounced (Maduro et al., 2005; McGhee et al., 2007). Knockout of ELT-7 pro- duces a developmentally wild-type animal, because many of the genes for endoderm differentiation controlled by ELT-7 are redun- dantly controlled by ELT-2. ELT-7 also controls expression of pha-4, a transcription factor that in turn controls pharyngeal development and nematode longevity (Mango et al., 1994; Panowski et al., 2007; Murray et al., 2008). These data indicate ELT-2 as the primary GATA transcription factor involved in controlling intestinal development and immunity. One phenotype seen when expression of elt-2 is reduced by RNA interference (RNAi) is distension of the C. elegans intestine (Kerry et al., 2006; Shapira et al., 2006). Many models of C. 0145-305X/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.dci.2010.12.008