Identification and function of an evolutionarily conserved signaling intermediate in Toll pathways (ECSIT) from Crassostrea hongkongensis

Dev Comp Immunol. 2015 Nov;53(1):244-52. doi: 10.1016/j.dci.2015.07.015. Epub 2015 Jul 20.

Abstract

Evolutionarily conserved signaling intermediate in Toll pathways (ECSIT) is a multifunctional adaptor protein that plays a key role in the regulation of the oxidative phosphorylation (OXPHOS) system, bone morphogenetic protein (BMP) pathway and Toll-like receptor (TLR) signaling pathway in mammals. However, the function of ECSIT homologs in mollusks, the second most diverse group of animals, is not well understood. In this study, we identified an ECSIT homolog in the Hong Kong oyster Crassostrea hongkongensis (ChECSIT) and investigated its biological functions. The full-length cDNA of ChECSIT is 1734 bp and includes an open reading frame (ORF) of 1074 bp that encodes a polypeptide of 451 amino acids. The predicted ChECSIT protein shares similar structural characteristics with other known ECSIT family proteins. Quantitative real-time PCR analysis revealed that ChECSIT mRNA is broadly expressed in all of the examined tissues and at different stages of embryonic development; its transcript level could be significantly up-regulated by challenge with microorganisms (Vibrio alginolyticus, Staphylococcus haemolyticus and Saccharomyces cerevisiae). In addition, ChECSIT was found to be located primarily in the cytoplasm, and its overexpression stimulated the transcriptional activity of an NF-κB reporter gene in HEK293T cells. These findings suggest that ChECSIT might be involved in embryogenesis processes and immune responses in C. hongkongensis.

Keywords: Crassostrea hongkongensis; ECSIT; Innate immunity; NF-κB; TLR signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics*
  • Adaptor Proteins, Signal Transducing / immunology
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Bone Morphogenetic Proteins / metabolism
  • Cell Line
  • Cloning, Molecular
  • Crassostrea / genetics
  • Crassostrea / immunology*
  • HEK293 Cells
  • Humans
  • Immunity, Innate / immunology*
  • Molecular Sequence Data
  • NF-kappa B / genetics
  • Open Reading Frames / genetics
  • Oxidative Phosphorylation
  • RNA, Messenger / genetics
  • Saccharomyces cerevisiae / immunology
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Signal Transduction / immunology
  • Staphylococcus haemolyticus / immunology
  • Toll-Like Receptors / metabolism*
  • Transcription, Genetic / genetics
  • Transcriptional Activation
  • Vibrio alginolyticus / immunology

Substances

  • Adaptor Proteins, Signal Transducing
  • Bone Morphogenetic Proteins
  • NF-kappa B
  • RNA, Messenger
  • Toll-Like Receptors