Molecular cloning and characterization of cathepsin F gene from olive flounder Paralichthys Olivaceus

Expression of Cathepsin F in response to bacterial challenges in Yesso scallop Patinopecten yessoensis

Cathepsin F is a unique papain cysteine proteinase with highly conserved structures: catalytic triad and a cystatin domain contained in the elongated N-terminal pro-region. It has been reported that cathepsin F is associated with the establishment of innate immune in several vertebrate including fish in aquaculture, but not known in bivalves. In this study, we firstly identified and characterized cathepsin F in the Yesso scallop (Patinopecten yessoensis). The protein structural and phylogenetic analyses were then conducted to determine its identity and evolutionary position. We've also investigated the expression levels of cathepsin F gene at different embryonic developmental stages, in healthy adult tissues and especially in the hemocytes and hepatopancreas after Gram-positive (Micrococcus luteus) and negative (Vibrio anguillarum) challenges using quantitative real-time PCR (qPCR). Cathepsin F was significantly up-regulated 3 h after infection of V. anguillarum in hemocytes, suggesting its participation in immune response. Our findings have provided strong evidence that cathepsin F may be a good target for enhancing the immune activity in Yesso scallop.

The involvement of cathepsin F gene (CTSF) in turbot (Scophthalmus maximus L.) mucosal immunity

Cathepsin F (CTSF) is a recently described papain-like cysteine protease and unique among cathepsins due to an elongated N-terminal pro-region, which contains a cystatin domain. CTSF likely plays a regulatory role in processing the invariant chain which is associated with the major histocompatibility complex (MHC) class II. In this regard, we identified the CTSF gene of turbot as well as its protein structure, phylogenetic relationships, and expression patterns in mucosal tissues following Vibrio anguillarum and Streptococcus iniae challenge. We also determined the expression patterns of CTSF in mucosal tissues after vaccinated with the formalin-inactivated V. vulnificus whole-cell vaccine. Briefly, turbot CTSF gene showed the closest relationship with that of Paralichthys olivaceus in phylogenetic analysis. And CTSF was ubiquitously expressed in all tested tissues with the highest expression level in gill. In addition, CTSF gene showed different expression patterns following different bacterial challenge. The significant quick regulation of CTSF in mucosal surfaces against infection indicated its roles in mucosal immunity. Functional studies should further characterize avail utilization of CTSF function to increase the disease resistance of turbot in maintaining the integrity of the mucosal barriers against infection and to facilitate selection of the disease resistant family/strain in turbot.

Expression Analysis of Cathepsin F during Embryogenesis and Early Developmental Stage in Olive Flounder (Paralichthys olivaceus)

Cathepsins are members of the multigene family of lysosomal cysteine proteinases and have regulated function in several life processes. The potential role of cathepsin F cysteine gene was expected as protease in the yolk processing mechanism during early developmental stage, but expression analysis was unknown after fertilization. The alignment analysis showed that amino acid sequence of cathepsin F from olive flounder liver expressed sequence tag (EST) homologous to cathepsin F of other known cathepsin F sequences with 87-98% identity. In this study, we examined the gene expression analysis of cathepsin F in various tissues at variety age flounder. Tissue distribution of the cathepsin F mRNA has been shown to be ubiquitous and constitutive pattern regardless of age in each group, although derived from cDNA library using liver sample. The mRNA level of cathepsin F more increased as developmental proceed during embryogenesis and early developmental stage, especially increased in the blastula, hatching stage and 3 days post hatching (dph). As a result, it may suggest that the proteolysis of yolk proteins (YPs) has been implicated as a mechanism for nutrient supply during early larval stages in olive flounder.