Drosophila Thor participates in host immune defense and connects a translational regulator with innate immunity.
Thor has been identified as a new type of gene involved in Drosophila host immune defense. Thor is a member of the 4E-binding protein (4E-BP) family, which in mammals has been defined as critical regulators in a pathway that controls initiation of translation through binding eukaryotic initiation factor 4E (eIF4E). Without an infection, Thor is expressed during all developmental stages and transcripts localize to a wide variety of tissues, including the reproductive system. In response to bacterial infection and, to a lesser extent, by wounding, Thor is up-regulated. The Thor promoter has the canonical NFkappaB and associated GATA recognition sequences that have been shown to be essential for immune induction, as well as other sequences commonly found for Drosophila immune response genes, including interferon-related regulatory sequences. In survival tests, Thor mutants show symptoms of being immune compromised, indicating that Thor may be critical in host defense. In contrast to Thor, Drosophila eIF4E is not induced by bacterial infection. These findings for Thor provide the first evidence that a 4E-BP family member has a role in immune induction in any organism. Further, no gene in the translation initiation pathway that includes 4E-BP has been previously found to be immune induced. Our results suggest either a role for translational regulation in humoral immunity or a new, nontranslational function for 4E-BP type genes.
Bernal
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Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, Houston, TX 77005, USA.
Kimbrell
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DA
D000595:Amino Acid Sequence; D000818:Animals; D001424:Bacterial Infections / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004198:Disease Susceptibility; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics / Q000276:immunology*; D050981:Erythroid-Specific DNA-Binding Factors; D039561:Eukaryotic Initiation Factor-4E; D005786:Gene Expression Regulation; D017344:Genes, Insect; D020022:Genetic Predisposition to Disease; D007121:Immunocompetence / Q000235:genetics*; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D039561:Eukaryotic Initiation Factor-4E; D019476:Insect Proteins; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D010448:Peptide Initiation Factors; C410006:Thor protein, Drosophila; D014157:Transcription Factors