Molecular Cloning And Expression Analysis Of Mannose Receptor In Grass Carp(Ctenopharyngodon Idella)

Mannose receptor (MR) is one of the members of pattern-recognition receptors (PRRs), which not only plays a significant role in innate immunity responses through binding to the pathogen-associated molecular patterns (PAMPs) presented on surfaces of microorganisms, but also in acquired immune response through processing and presenting antigens. Much work on MR has been done in human and mice while little in fish. In this study, we first cloned and characterized mannose receptor in grass carp (gcMR). The expression profiles of gcMR mRNA expression in different tissues, during embryonic development and Aeromonas hydrophila infection were assessed using real-time quantitative reverse transcription PCR (qRT-PCR). The results were as follows:1. The full-length gcMR contained5291bp, consisted of a5’terminal untranslated region (UTR) of88bp, a3’UTR of904bp, and an open reading frame (ORF) of4299bp encoding a polypeptide of1432amino acids. The predicted amino acid sequences showed that gcMR contained a signal peptide, a cysteine-rich (CR) domain, a fibronectin type II (FN II) domain, eight C-type lectin-like domains (CTLDs), a transmembrane domain and a short cytoplasmic domain.2. During embryonic development, gcMR transcript levels were highest at cleavage stage.3. gcMR were constitutively expressed in different organs with the higher expression in spleen and head kidney.4. The up-regulation expression of gcMR, IL-1β and TNF-a in liver, spleen, head kidney and intestine after Aeromonas hydrophila infection indicating its involvement in innate immune regulation during bacterial infections.