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Mitogen-activated protein kinase (MAPK) signaling pathway plays an important role in cellular response to inflammatory cytokines, environmental stress and pathogenic infection, However, compared with mammals and insects, the potential function of p38 MAPK from Chinese shrimp ( Fenneropenaeus chinensis ) in response to viruses and bacterial infection is limited. In the study, the immune responses of four genes MKK3, MKK4, p38 and ATF-2 from F. chinensis were investigated in defending against white spot syndrome virus (WSSV), Vibrio anguillarum ( V. anguillarum ) and Staphylococcus aureus ( S. aureus ) infection. Results demonstrated that the expression levels of these four genes were apparently modulated in hemocytes and gills when shrimp were stimulated by WSSV or bacteria, particularly at 3–24 h after infection. MKK3, p38 and ATF-2 were most sensitive to V. anguillarum (Gram-negative bacteria), followed by WSSV and S. aureus (Gram-positive bacteria), while MKK4 gene was most sensitive to S. aureus , followed by WSSV and V. anguillarum . Knockdown of Fcp38 by RNA interference (RNAi) resulted in a reduction in the expression of FcMKK3 and FcATF-2 . The results indicate that p38MAPK signaling pathway plays a role in defending against viral and bacterial infections in F. chinensis . [ABSTRACT FROM AUTHOR]

Abstract: Diseases caused by viruses are the greatest challenge to worldwide shrimp aquaculture. C-type lectins may play an important role in shrimp immunity. The gene encoding FcCTL, a C-type lectin-like protein, was isolated from Fenneropenaeus chinensis and characterized. This gene was composed of five exons spanning 2470 base pairs (bp). Intron 1 contained a possible promoter and many potential transcription factor binding sites, such as those for TATA binding protein, CREB, SRF, Ttk and three sites for HSFs. The 5′-flanking sequences (723bp) of FcCTL contained typical CTF (CAAT box) and transcriptional regulatory elements, such as CF1, CF2-II and HSEs, observed in immunity-related genes in other arthropods. A series of FcCTL promoter sequences, especially the full-length promoter, generated an increase in luciferase expression relative to the promoter-less vector; furthermore, the expression of FcCTL was induced by heat shock and white spot syndrome virus (WSSV) challenge. These results extended our previous findings and provided insights into the molecular regulation of FcCTL gene expression, which would be helpful for shrimp viral disease control. [Copyright &y& Elsevier]