Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
Department of Clinical Immunology, Children's Hospital of Fudan University, Shanghai 201102, China.
Int J Mol Sci. 2021 Feb 25;22(5):2284. doi: 10.3390/ijms22052284.
Transcytosis of polymeric IgA and IgM from the basolateral surface to the apical side of the epithelium and subsequent secretion into mucosal fluids are mediated by the polymeric immunoglobulin receptor (pIgR). Secreted IgA and IgM have vital roles in mucosal immunity in response to pathogenic infections. Binding and recognition of polymeric IgA and IgM by pIgR require the joining chain (J chain), a small protein essential in the formation and stabilization of polymeric Ig structures. Recent studies have identified marginal zone B and B1 cell-specific protein (MZB1) as a novel regulator of polymeric IgA and IgM formation. MZB1 might facilitate IgA and IgM transcytosis by promoting the binding of J chain to Ig. In this review, we discuss the roles of pIgR in transcytosis of IgA and IgM, the roles of J chain in the formation of polymeric IgA and IgM and recognition by pIgR, and focus particularly on recent progress in understanding the roles of MZB1, a molecular chaperone protein.
多聚免疫球蛋白受体（pIgR）介导多聚免疫球蛋白 A（pIgA）和多聚免疫球蛋白 M（pIgM）从基底外侧表面向上皮顶端的转胞运输，以及随后分泌到黏膜液中。分泌型 IgA 和 IgM 在针对致病感染的黏膜免疫中具有重要作用。pIgR 对 pIgA 和 pIgM 的结合和识别需要连接链（J 链），这是形成和稳定多聚 Ig 结构所必需的小蛋白。最近的研究确定边缘区 B 和 B1 细胞特异性蛋白（MZB1）是多聚 IgA 和 IgM 形成的新型调节剂。MZB1 可能通过促进 J 链与 Ig 的结合来促进 IgA 和 IgM 的转胞运输。在这篇综述中，我们讨论了 pIgR 在 IgA 和 IgM 转胞运输中的作用、J 链在多聚 IgA 和 IgM 形成和 pIgR 识别中的作用，并特别关注了理解分子伴侣蛋白 MZB1 作用的最新进展。
