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Series GSE136058 Query DataSets for GSE136058
Status Public on Dec 31, 2019
Title Transcriptome of the nematode Caenorhabditis elegans infected by Bacillus thuringiensis
Organism Caenorhabditis elegans
Experiment type Expression profiling by high throughput sequencing
Summary In the past decade, the paradigm which claimed that invertebrate immune systems lack specificity has been reconsidered. Accumulating evidence supports that invertebrate immune systems are able to mount specific responses to the pathogen species-, and even to the pathogen strain-level. However, the underlying molecular mechanisms behind invertebrate immune specificity remain mostly unknown. Studying the molecular basis of invertebrate immune specificity in a genetically tractable model, such as the nematode Caenorhabditis elegans, has the potential to reveal insights into the immune systems of other metazoans, including humans. We chose to study the mechanisms of specific immune responses of the worm to two different pathogenic strains of the Gram-positive bacterium Bacillus thuringiensis (MYBY18247 and MYBT18679), because there is phenotypic evidence of specific genotype-genotype interactions between this host-pathogen pair. We did an initial RNA-Seq experiment upon pathogen exposure and found that 9% of the differentially expressed genes change their expression in different ways when comparing the two pathogen strains. Through promoter region motif enrichment analysis, we found the GATA transcription factor ELT-2 is responsible for the pathogen strain-specific transcriptomic response. Upon elt-2 knockdown worms exposed to MYBT18679 display lower survival rate coupled with higher intestinal damage than non-infected controls. Additionally, by performing further genetic analysis using gene knockdown and knockout, we found that the p38 MAPK pathway acts likely in parallel to elt-2 and the transcription factor skn-1 cooperates with elt-2 to promote resistance to MYBT18679. On the other hand, elt-2 knockdown leads to a substantially higher survival rate, together with lower intestinal tissue damage compared to control worms, upon exposure to MYBT18247, another pathogenic Bacillus thuringiensis strain. The MYBT18247 pathogen load of elt-2(RNAi) worms compared to control worms remained unchanged, suggesting the elt-2 negatively regulates tolerance towards MYBT18247. We found that tolerance to MYBT18247 was positively regulated by the transcription factors: FOXO daf-16, bZip zip-2, nhr-99 and nhr-193. To identify elt-2 negatively-regulated downstream targets that could promote tolerance to MYBT18247, we performed a second RNA-Seq experiment, this time including elt-2(RNAi) worms exposed to both pathogenic strains. We found four genes negatively regulated by elt-2: cdr-2, poml-3, dhs-30 and tre-3, with putative function in detoxification and lipid metabolism, which can mediate tolerance to MYBT18247. We conclude that ELT-2 coordinates strain-specific immune responses in this invertebrate host and promotes resistance upon exposure to MYBT18679, while it negatively regulates tolerance to MYBT18247. The response is likely to be specific to the crystal pore-forming toxins produced by this pathogen.
 
Overall design mRNA profiles of wild type (WT) C.elegans exposed to either Bacillus thuringiensis B-18247, B-18679 and B-18407 or E. coli OP50 at 2h, 6h, 12h or 24h were generated by deep sequencing (4 replicates), using Illumina HiSeq2000.
 
Contributor(s) Zarate-Potes A, Dierking K, Schulenburg H
Citation(s) 32970778
Submission date Aug 20, 2019
Last update date Mar 03, 2021
Contact name Hinrich Schulenburg
E-mail(s) hschulenburg@zoologie.uni-kiel.de
Organization name Christian-Albrechts-Universitaet zu Kiel
Department Evolutionary Ecology and Genetics, Zoological Institute
Lab Schulenburg Group
Street address Am Botanischen Garten 1-9
City Kiel
ZIP/Postal code 24118
Country Germany
 
Platforms (1)
GPL13657 Illumina HiSeq 2000 (Caenorhabditis elegans)
Samples (64)
GSM4040269 D1106_BT247_2h_rep1
GSM4040270 D1107_BT247_2h_rep2
GSM4040271 D1108_BT247_2h_rep3
Relations
BioProject PRJNA561143
SRA SRP218889

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Supplementary file Size Download File type/resource
GSE136058_BT_counts_table.txt.gz 2.1 Mb (ftp)(http) TXT
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Raw data are available in SRA
Processed data are available on Series record

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