Molecular cloning and expression analysis of mannose receptor C type 1 in grass carp (Ctenopharyngodon idella)

Mannose receptor C type 1 (MRC1) is a pattern-recognition receptor (PRR) which plays a significant role in immune responses. Much work on MRC1 has been done in mammals and birds while little in fish. In this study, we cloned and characterized MRC1 in grass carp (gcMR). The full-length gcMR contained 5291bp encoding a putative protein of 1432 amino 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. gcMR were constitutively expressed in different organs with the higher expression in spleen and head kidney. During embryonic development, gcMR transcript levels were highest at cleavage stage. The up-regulation expression of gcMR, IL-1β and TNF-α in liver, spleen, head kidney and intestine after Aeromonas hydrophila infection indicating it involved in innate immune regulation during bacterial infections.