Cloning and characterization of the bovine polymeric immunoglobulin receptor-encoding cDNA.
ABSTRACT Trans-epithelial transport of polymeric immunoglobulins (pIg) into mucosal and glandular secretions is carried out by the pIg receptor (pIgR). Therefore, expression of the pIgR gene in epithelial cells of mucosal and glandular tissues is an absolute requirement for achieving mucosal immunity. We report the cloning and characterization of the bovine pIgR cDNA. Three overlapping cDNA clones with a total length of 3608 bp yielded an open reading frame encoding a 757-amino-acid (aa) transmembrane (TM) glycoprotein. Although polymorphism was found in two separate clones, Northern blot analysis showed a single pIgR mRNA (approx. 3.8 kb) to be present in the mammary gland, liver, lung, kidney and intestine of a lactating cow. There was no detectable expression of pIgR in the spleen of the same animal. Comparison of the deduced bovine pIgR as sequence with those of rat, mouse, man and rabbit shows that this receptor is highly conserved both in aa sequence and structural organization. The degree of conservation in the TM sequence and the C-terminal cytoplasmic tail, which contains the various signals for intracellular trafficking of the receptor, is 65-73%. We also find a high degree of conservation (61-66%) in the ectoplasmic part of the receptor, known as the secretory component (SC), with an exception for that of the rabbit SC, which is much lower (47%). Among the five Ig-like domains in the SC, the N-terminal domain I, where the primary pIg-binding site is located, showed the highest (72-83%) aa sequence conservation.
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ABSTRACT: The mucosal surfaces lining the gastrointestinal, respiratory and genitourinary tracts are continuously bombarded by potentially infectious agents such as bacteria, viruses, fungi, and parasites, in addition to soluble dietary and environmental substances. The first line of specific immunological defense against these environmental antigens is secretory IgA (SIgA) (Brandtzaeg et al., 1997; Lamm, 1997), which is produced by selective transport of polymeric IgA (pIgA) across epithelial cells lining mucosal surfaces (Kaetzel, 2005; Kaetzel and Mostov, 2005; Norderhaug et al., 1999). The magnitude of this transport process is impressive; it has been estimated that ~3 g of SIgA are transported daily into the intestines of the average adult (Conley and Delacroix, 1987; Mestecky et al., 1986). Transport of polymeric immunoglobulins (IgA and, to a lesser extent, IgM) across mucosal epithelial cells is mediated by a transmembrane glycoprotein called the polymeric immunoglobulin receptor (pIgR).01/1970: pages 43-89;
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ABSTRACT: The submandibular and parotid glands are the main sources of immunoglobulins A (IgAs) in human and rat saliva. These glands express the polymeric immunoglobulin receptor (pIgR), which transports IgAs into saliva. The main source of IgAs in saliva and pIgR expression in salivary glands has not been well documented in cattle. Expressions of pIgR were determined in the major bovine salivary glands (sublingual, submandibular, and parotid) by RT-PCR for mRNA and by Western blot analysis and immunohistochemistry (IHC) using an anti-human pIgR antibody for protein. The protein detected with the antibody was identified by nano-liquid chromatography-quadrupole time of flight mass spectrometry. Additionally, the distribution of Ig-producing plasma cells was analyzed by IHC. RT-PCR showed that pIgR was expressed in the sublingual and submandibular glands, but not in the parotid gland. Higher protein levels were observed in sublingual glands than in submandibular glands by Western blot. By IHC, pIgR was mainly located on the apical side of the cytoplasmic membrane in the sublingual gland, whereas it was observed only on the basal side in the submandibular gland. The highest density of plasma cells expressing IgAs was observed in the sublingual gland. These results suggest that the sublingual gland plays an important role in first-line defence of the oral cavity in cattle in contrast to humans and rats.The Veterinary Journal 02/2013; 197(2). DOI:10.1016/j.tvjl.2012.12.030 · 2.17 Impact Factor
Chapter: IgA and Antigen Sampling[Show abstract] [Hide abstract]
ABSTRACT: As the primary immunoglobulin class in mucosal secretions, secretory immunoglobulin A (SIgA) antibodies function as the immunological “ frontline,” protecting the vulnerable surfaces of the intestinal epithelium from pathogenic bacteria, viruses, and toxins encountered in the normal human diet. SIgA also serves as a barrier to commensal microbiota (Johansen et al., 1999; Kelly et al., 2005; Macpherson et al., 2000;), some of which are opportunistic pathogens capable of causing disease if afforded access to the systemic compartment. Protection is achieved primarily by “immune exclusion,” a general term referring to the ability of SIgA to coat intestinal antigens, thereby (1) preventing their attachment to epithelial cell receptors and (2) promoting their clearance from the intestinal lumen via peristalsis (Lamm, 1997). SIgA is also of critical importance to neonates whose mucosal immune systems are in the early stages of development. In humans, SIgA is the major immunoglobulin class in colostrum and breast milk, providing passive immunity to a variety of enteric pathogens (Brandtzaeg, 2003).10/2007: pages 203-220;