Barrier epithelial cells lining the mucosal surfaces of the gastrointestinal and respiratory tracts interface directly with the environment. As such, these tissues are continuously challenged to maintain a healthy equilibrium between immunity and tolerance against environmental toxins, food components, and microbes. An extracellular mucus barrier, produced and secreted by the underlying epithelium plays a central role in this host defense response. Several dedicated molecules with a unique tissue-specific expression in mucosal epithelia govern mucosal homeostasis. Here, we review the biology of Inositol-requiring enzyme 1β (IRE1β), an ER-resident endonuclease and paralogue of the most evolutionarily conserved ER stress sensor IRE1α. IRE1β arose through gene duplication in early vertebrates and adopted functions unique from IRE1α which appear to underlie the basic development and physiology of mucosal tissues.

排列在胃肠道和呼吸道粘膜表面的屏障上皮细胞直接与环境接触。因此，这些组织不断受到挑战，以在免疫力和对环境毒素、食物成分和微生物的耐受性之间保持健康的平衡。由下层上皮细胞产生和分泌的细胞外粘液屏障在宿主防御反应中起着核心作用。几种在粘膜上皮细胞中具有独特组织特异性表达的专用分子控制粘膜稳态。在这里，我们回顾了需要肌醇的酶 1β (IRE1β) 的生物学，IRE1β 是一种内质网驻留的核酸内切酶，也是进化上最保守的内质网应激传感器 IRE1α 的旁系同源物。