Transcriptome profiling the gills of amoebic gill disease (AGD)-affected Atlantic salmon (Salmo salarL.): a role for tumor suppressor p53 in AGD pathogenesis?

Abstract

Neoparamoeba spp. are amphizoic amoebae with the capacity to colonize the gills of some marine fish, causing AGD. Here, the gill tissue transcriptome response of Atlantic salmon ( Salmo salar L.) to AGD is described. Tanks housing Atlantic salmon were inoculated with Neoparamoeba spp. and fish sampled at time points up to 8 days postinoculation (pi.). Gill tissues were taken from AGD-affected fish, and a DNA microarray was used to compare global gene expression against tissues from AGD-unaffected fish. A total of 206 genes, representing 190 unique transcripts, were reproducibly identified as up- or downregulated in response to Neoparamoeba spp. infection. Informative transcripts having GO biological process identifiers were grouped according to function. Although a number of genes were placed into each category, no distinct patterns were observed. One Atlantic salmon cDNA that was upregulated in infected gill relative to noninfected gill at 114 and 189 h pi. showed significant identity with the Xenopus, mouse, and human anterior gradient-2 (AG-2) homologs. Two Atlantic salmon AG-2 mRNA transcripts, designated asAG-2/1 and asAG-2/2, were cloned, sequenced, and shown to be predominantly expressed in the gill, intestine, and brain of a healthy fish. In AGD-affected fish, differential asAG-2 expression was confirmed in samples used for microarray analyses as well as in AGD-affected gill tissue taken from fish in an independent experiment. The asAG-2 upregulation was restricted to AGD lesions relative to unaffected tissue from the same gill arch, while p53 tumor suppressor protein mRNA was concurrently downregulated in AGD lesions. Differential expression of p53-regulated transcripts, proliferating cell nuclear antigen and growth arrest and DNA damage-inducible gene-45β (GADD45β) in AGD lesions, suggests a role for p53 in AGD pathogenesis. Thus AGD may represent a novel model for comparative analysis of p53 and p53-regulated pathways.

Molecular profiling of the gilthead sea bream (Sparus aurata L.) response to chronic exposure to the myxosporean parasite Enteromyxum leei

“…Ourth et al (2007) have suggested that MBL could be used as a genetic marker for disease resistance in the different strains of cultured catfish, as those more resistant to Edwardsiella ictaluri had nearly three fold higher levels of serum MBL. In other infection studies the transcriptomic responses of MBL were dependent on the pathogen involved, as demonstrated by the 4.2-fold down-regulation of the MBL gene in the gills of AGD-affected Atlantic salmon (Morrison et al, 2006), and the 2-fold up-regulation in juvenile Atlantic salmon infected with saprolegniasis, a fungal infection (Roberge et al, 2007).…”

“…Other immune parameters such as the phagocytic activity of macrophages and/or respiratory burst of leukocytes were also decreased in different hosts infected with other parasites (Mustafa et al, 2000;Fast et al, 2002;Scharsack et al, 2004;Karagouni et al, 2005). At the transcriptional level, the parasite-mediated amoebic gill disease (AGD) in Atlantic salmon produced a marked up-regulation of gene expression in early stages (4-8 days) of infection (Morrison et al, 2006), whereas at medium (19 days) (Wynne et al, 2008a) and long term exposure (36 days) (Young et al, 2008), a strong overall gene suppression was evident in the immune response, transport, translation and catalytic activity functional categories. This late suppression is in accordance with that observed in the present model of long term exposure to the myxosporean.…”

“…In salmonids, several studies have focused on the identification of molecular biomarkers in response to bacterial (Rise et al, 2004;Ewart et al, 2005;Baerwald et al, 2008), viral (Jorgensen et al, 2008;MacKenzie et al, 2008), fungal (Roberge et al, 2007) or parasitic infections (Morrison et al, 2006;Skugor et al, 2008;Wynne et al, 2008aWynne et al, , 2008b. The immune response of channel and blue catfish to bacterial (Peatman et al, 2007(Peatman et al, , 2008 and that of Japanese flounder to bacterial (Matsuyama et al, 2007a), 4 viral (Byon et al, 2005(Byon et al, , 2006, and parasitic (Matsuyama et al, 2007b) infections have also been studied.…”

Interferon type I and type II responses in an Atlantic salmon (Salmo salar) SHK-1 cell line by the salmon TRAITS/SGP microarray

“…Interferon type I and type II responses in an Atlantic salmon (Salmo salar) SHK-1 cell line by the salmon TRAITS/SGP microarray. Physiol Genomics 32: [33][34][35][36][37][38][39][40][41][42][43][44] 2007. First published September 5, 2007; doi:10.1152/physiolgenomics.00064.2007 RNA was hybridized to an Atlantic salmon cDNA microarray (salmon 17K feature TRAITS/SGP array) in order to assess differential gene expression in response to IFN exposure.…”

Predominant expression and cellular distribution of fish Agr2 in renal collecting system

“…As shown in Fig. 1B, CagAgr2 belongs to the fish Agr2 family including zebrafish ZAgr2, Atlantic salmon SAgr2 (Morrison et al, 2006) and pufferfish TAgr2. Moreover, this fish branch is grouped together with a branch including human HAGR2, mouse MAgr2 and chicken CAgr2 with a high bootstrap value (94% support), suggesting a closer relationship among these Agr2 genes.…”