[Molecular aspects of secretory IgA (S-IgA) in gut-associated lymphoid tissues].
Secretory IgA, which plays an important role in the defense of the exocrine tissue, is composed of a polymeric IgA, joining (J) chain and secretory component (SC). Polymeric IgA and J chain are produced by plasma cells and SC by glandular epithelial cells. We here described the molecular aspects of J chain and SC. Study of the J chain has been confined to vertebrates which produce immunoglobulin (Ig) because the function of J chain is considered to be a polymerization of Ig. Recent molecular studies indicate that the role of J chain has been questioned. The J chain is expressed in invertebrates, as well as, representative species of vertebrates and that J chain is a primitive polypeptide that arose before the evolution of Ig molecules. SC is a 80 kDa glycoprotein functioning as a receptor for J chain-containing polymeric Ig. The expression of SC is regulated by various inflammatory cytokines such as, IL-1, IL-4, IL-6, IL-8, IFN-gamma and TNF-alpha, suggesting SC upregulation in vivo in inflammatory conditions. The human SC cDNA analysis reveals that it consisted of 11 exons with no functional TATA-box or CCAAT-box in the putative promoter region. Further upstream, there are several interesting motifs such as NF-kB and IFN-gamma response element, suggesting possible regulation of SC by cytokines through cellular signal transduction pathways.
Moro
I
I
Department of Pathology, Nihon University School of Dentistry.
Komiyama
K
K
Kusama
K
K
Iwase
T
T
Asano
M
M
Takenouchi
N
N
D000818:Animals; D006801:Humans; D007071:Immunoglobulin A, Secretory; D007144:Immunoglobulin J-Chains / Q000235:genetics / Q000502:physiology; D010802:Phylogeny; D019056:Receptors, Polymeric Immunoglobulin; D012635:Secretory Component / Q000235:genetics / Q000502:physiology
D007071:Immunoglobulin A, Secretory; D007144:Immunoglobulin J-Chains; D019056:Receptors, Polymeric Immunoglobulin; D012635:Secretory Component