PoCRIP1, Paralichthys olivaceus cysteine-rich intestinal protein 1: molecular characterization, expression analysis upon Edwardsiella tarda challenge and a possible role in the immune regulation.

Cysteine-rich intestinal protein (CRIP) is a LIM domain protein containing a zinc-finger motif and plays a role in the regulation of the inflammatory immune response. In the present study, we isolated a CRIP1 cDNA, designated PoCRIP1, from an olive flounder Paralichthys olivaceus intestine cDNA library by EST analysis. The PoCRIP cDNA consists of 421 bp with a polyadenylation signal sequence, AATAAA, and a poly(A) tail; it encodes a polypeptide of 76 amino acids containing a double zinc-finger motif (Cys(2)HisCys and Cys(4) sequences). The deduced amino acid sequence of PoCRIP1 showed 75.3-94.7% homology with CRIP1s of other species, including mammals. The PoCRIP1 transcript was highly expressed in the intestine and pyloric ceca and moderately expressed in the gill, heart, kidney, liver, muscle, spleen, skin, and stomach of normal conditioned flounder. Inducible expression of the PoCRIP1 transcript was observed in flounder challenged with Edwardsiella tarda, an economically important pathogen for aquaculture of flounder. Over-expression of PoCRIP1 augmented p65-driven flounder IL-6 promoter activity in HINAE cells. These results suggest that PoCRIP1 may function in the immune response of the flounder through the regulation of cytokine expression.