Nematoda: The Caenorhabditis elegans Model for Innate Immunity – Interactions Between Worms and Pathogens, and Their Responses to Immunogenic Damage
The nematode worm Caenorhabditis elegans has evolved a sophisticated innate immune response that responds to viral, bacterial, and fungal infections. Because of the lack of an adaptive immune response, including specialized immune cells, the worm has become a powerful model for studying highly conserved basic features of innate immune responses. In this chapter we discuss the signaling pathways that mediate the immune response and features of the worm’s defenses against specific pathogens, as they are currently understood. In particular, recent unique discoveries in C. elegans that have provided valuable details on the interconnectedness between innate immunity, organismal stress resistance, and longevity pathways are highlighted—particularly in the context of how a simple animal can respond to environmental assaults to preserve both its somatic tissue and genetic material.
KeywordsCaenorhabditis elegans Innate immunity DNA damage MAP kinase Stress response Insulin signaling Toll-like receptor p38 signaling Viral defense RNA interference (RNAi) p53 tumor suppressor Surveillance immunity Cellular homeostasis
Ortholog of phosphoinositide 3-kinase (PI3K) p110 catalytic subunit.
Homologs of serine/threonine kinase Akt/PKB ortholog of the serine/threonine kinase Akt/PKB.
Leucine zipper transcription factor; ortholog of CREB/activating transcription factors.
bZip transcription factor involved in UPRmt.
Ortholog of human CCAAT7 enhancer binding protein gamma (CEBPG).
BH3 domain-containing protein involved in apoptosis.
Ortholog of human tumor suppressor p53.
Receptor tyrosine kinase; insulin/insulin growth factor receptor ortholog.
Serine/threonine kinase; ortholog of type II transforming growth factor (TGF)-β receptor.
Forkhead box O (FOXO) transcription factor in insulin-mediated signaling.
Beta-type insulin; homologous to human insulin.
Member of transforming growth factor (TGF)-β super family.
Ortholog of human neuropeptide FF receptors (1 and 2) and pyroglutamylated RF amide peptide receptor.
Ribonuclease involved in RNA interference.
Dicer-related helicase involved in RNA interference.
BH3 domain-containing protein involved in apoptosis.
Ortholog of vertebrate RAF protein.
Mitogen-activated protein kinase (MAPK) kinase involved in Ras-mediated signaling.
Mitogen-activated protein kinase (MAPK); ortholog of human extracellular signal-regulated kinase (ERK).
RNaseD homolog involved in RNA interference.
G-protein-coupled neuropeptide receptor; homolog of mammalian neuropeptide Y receptor.
Neuronal symmetry family member 1. Mitogen-activated protein kinase (MAPK) kinase; ortholog of mammalian ASK family of proteins.
G-protein-coupled receptor involved in neuronal signaling.
Mitogen-activated protein kinase (MAPK); ortholog of human p38 MAPK, orthologous to human mi MAPK (OMIM:600289); MAPK, orthologous to human MAPK (OMIM:600289).
Argonaute and PIWI family protein.
Double-stranded RNA (dsRNA)-binding protein involved in RNA interference.
Ortholog of human mitogen-activated protein kinase kinases (MAPKK) 3 and 6.
Orthologs of SMAD proteins.
Serine/threonine protein kinase; orthologous to type I transforming growth factor (TGF)-β receptors.
Toll/interleukin-1 receptor domain adapter protein; ortholog of human SARM.
Toll-like receptor protein.
Mitochondrial unfolded protein response.
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