title: Discovery of J chain in African lungfish (Protopterus dolloi, Sarcopterygii) using high throughput transcriptome sequencing: implications in mucosal immunity.
abstract: J chain is a small polypeptide responsible for immunoglobulin (Ig) polymerization and transport of Igs across mucosal surfaces in higher vertebrates. We identified a J chain in dipnoid fish, the African lungfish (Protopterus dolloi) by high throughput sequencing of the transcriptome. P. dolloi J chain is 161 aa long and contains six of the eight Cys residues present in mammalian J chain. Phylogenetic studies place the lungfish J chain closer to tetrapod J chain than to the coelacanth or nurse shark sequences. J chain expression occurs in all P. dolloi immune tissues examined and it increases in the gut and kidney in response to an experimental bacterial infection. Double fluorescent in-situ hybridization shows that 88.5% of IgM⁺ cells in the gut co-express J chain, a significantly higher percentage than in the pre-pyloric spleen. Importantly, J chain expression is not restricted to the B-cell compartment since gut epithelial cells also express J chain. These results improve our current view of J chain from a phylogenetic perspective.
authors: Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America.
authors: Luca
authors: L
authors: Tacchi
authors: Erin
authors: E
authors: Larragoite
authors: Irene
authors: I
authors: Salinas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004755:Enterobacteriaceae / Q000502:physiology; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D005399:Fishes / Q000235:genetics* / Q000276:immunology* / Q000382:microbiology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D018928:Immunity, Mucosal / Q000235:genetics*; D007075:Immunoglobulin M / Q000235:genetics / Q000276:immunology; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000166:cytology / Q000382:microbiology; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D016415:Sequence Alignment
chemical_list: D007075:Immunoglobulin M; D010455:Peptides
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