title: Functional characterization of chitinase-3 reveals involvement of chitinases in early embryo immunity in zebrafish.
abstract: The function and mechanism of chitinases in early embryonic development remain largely unknown. We show here that recombinant chitinase-3 (rChi3) is able to hydrolyze the artificial chitin substrate, 4-methylumbelliferyl-β-D-N,N',N″-triacetylchitotrioside, and to bind to and inhibit the growth of the fungus Candida albicans, implicating that Chi3 plays a dual function in innate immunity and chitin-bearing food digestion in zebrafish. This is further corroborated by the expression profile of Chi3 in the liver and gut, which are both immune- and digestion-relevant organs. Compared with rChi3, rChi3-CD lacking CBD still retains partial capacity to bind to C. albicans, but its enzymatic and antifungal activities are significantly reduced. By contrast, rChi3-E140N with the putative catalytic residue E140 mutated shows little affinity to chitin, and its enzymatic and antifungal activities are nearly completely lost. These suggest that both enzymatic and antifungal activities of Chi3 are dependent on the presence of CBD and E140. We also clearly demonstrate that in zebrafish, both the embryo extract and the developing embryo display antifungal activity against C. albicans, and all the findings point to chitinase-3 (Chi3) being a newly-identified factor involved in the antifungal activity. Taken together, a dual function in both innate immunity and food digestion in embryo is proposed for zebrafish Chi3. It also provides a new angle to understand the immune role of chitinases in early embryonic development of animals.
authors: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity, Department of Marine Biology, Ocean University of China, Qingdao 266003, China.
authors: Zinan
authors: Z
authors: Teng
authors: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity, Department of Marine Biology, Ocean University of China, Qingdao 266003, China.
authors: Chen
authors: C
authors: Sun
authors: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity, Department of Marine Biology, Ocean University of China, Qingdao 266003, China.
authors: Shousheng
authors: S
authors: Liu
authors: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity, Department of Marine Biology, Ocean University of China, Qingdao 266003, China.
authors: Hongmiao
authors: H
authors: Wang
authors: Laboratory for Evolution & Development, Institute of Evolution & Marine Biodiversity, Department of Marine Biology, Ocean University of China, Qingdao 266003, China. Electronic address: sczhang@ouc.edu.cn.
authors: Shicui
authors: S
authors: Zhang
mesh_terms: D000818:Animals; D002176:Candida albicans / Q000276:immunology*; D002177:Candidiasis / Q000201:enzymology / Q000276:immunology / Q000662:veterinary*; D002688:Chitinases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000201:enzymology* / Q000276:immunology / Q000382:microbiology; D005393:Fish Diseases / Q000201:enzymology / Q000276:immunology* / Q000382:microbiology; D015870:Gene Expression; D007113:Immunity, Innate; D008099:Liver / Q000201:enzymology; D009928:Organ Specificity; D011485:Protein Binding; D015027:Zebrafish / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D029961:Zebrafish Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*
chemical_list: D029961:Zebrafish Proteins; D002688:Chitinases; C000596166:chia.3 protein, zebrafish
keywords: Anti-fungal activity; Candida albicans; Chitinase; Maternal immunity; Zebrafish