Location: Warmwater Aquaculture Research UnitTitle: Microfibrillar associated protein 4 mfap4 genes in catfish play a novel role in innate immune responses Author
|Waldbieser, Geoffrey - Geoff|
Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2011
Publication Date: 1/11/2011
Publication URL: http://handle.nal.usda.gov/10113/55441
Citation: Niu, D., Peatman, E., Liu, H., Lu, J., Kucuktas, H., Liu, S., Sun, F., Zhang, H., Feng, T., Zhou, Z., Terhune, J., Waldbieser, G.C., Li, J., Liu, Z. 2011. Microfibrillar associated protein 4 mfap4 genes in catfish play a novel role in innate immune responses. Developmental and Comparative Immunology. 35:568-579. Interpretive Summary: Commercial catfish producers experience significant losses due to disease in earthen pond culture but molecular mechanisms of catfish immunity are not well understood. In this research, multiple MFAP4 genes were identified in the catfish genome to assist investigations into the potential of the MFAP4 proteins as pathogen receptors. Experimental challenges with two bacterial pathogens demonstrated upregulation of the genes after infection. This research demonstrates the potential for a novel role for MFAP4 proetins in fish immune responses.
Technical Abstract: The lectin pathway of the complement system is characterized by two groups of soluble pattern recognition molecules, mannose-binding lectins (MBLs) and ficolins. These molecules recognize and bind carbohydrates in pathogens and activate complement leading to opsonization, leukocyte activation, and direct pathogen killing. While MBLs have been reported in many fish species, ficolins do not appear to be present in the teleost lineage, despite their importance in invertebrate and higher vertebrate innate immunity. A protein with a similar fibrinogen-like domain, microfibrillar-associated protein 4, MFAP4, is present in fish, albeit with no described immune function. We examined whether MFAP4 genes in fish may potentially act as pathogen receptors in the absence of ficolin. We isolated and characterized five MFAP4 genes from channel catfish. Linkage mapping and phylogenetic analysis indicated that at least three of the catfish MFAP4 genes are tightly clustered on a single chromosome, suggesting that they may have arisen through tandem duplication. Divergent, duplicated families of MFAP4 genes are also present in other teleost species. Expression analysis of the catfish MFAP4 transcripts revealed unique patterns of homeostatic expression among the genes in gill, spleen, skin, liver, and muscle. Expression of the five MFAP4 transcripts showed significant changes in expression as soon as 4 h after infection with either Edwardsiella ictaluri or Flavobacterium columnare with modulation of expression continuing up to 7 d following pathogen exposure. Several different tissues and gene-specific patterns were captured and transcript expression changes of >30-fold were observed over the course of the bacterial challenges. Our results suggest a novel role for MFAP4 in teleost immune responses.