Miró-Julià C, Escoda-Ferran C, Carrasco E, Moeller J B, Vadekaer D F, Gao X, Paragas N, Oliver J, Holmskov U, Al-Awqati Q, Lozano F
Grup d'Immunoreceptors, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centre Esther Koplowitz, Barcelona, Spain.
Tissue Antigens. 2014 Apr;83(4):273-85. doi: 10.1111/tan.12330.
S5D-SRCRB is a novel mouse secretory glycoprotein belonging to the ancient and highly conserved scavenger receptor cysteine-rich superfamily of protein receptors. Available evidence indicates that S5D-SRCRB interacts with conserved microbial cell wall components, as well as with some endogenous proteins, and presents a restricted tissue expression pattern. This study further analyzes the expression of S5D-SRCRB along the mouse urogenital tract. Immunohistochemical staining for S5D-SRCRB was observed in spermatocytes from seminiferous tubules and in the epithelial surface from urethra and bladder, as well as in kidney tubules, mainly from medulla and papilla. Double stainings showed that S5D-SRCRB is expressed in both principal (P) and intercalated (IC) cells from renal collecting ducts (CD). By using an in vitro cell model of IC cell differentiation, preferential expression of S5D-SRCRB was observed in the apical border of terminally differentiated IC. Colocalization of S5D-SRCRB with galectin-3 (Gal-3) was also observed in kidney and bladder, but not in testis, supporting concurrent biochemical studies demonstrating the carbohydrate-dependent interaction of Gal-3 and S5D-SRCRB. Furthermore, upregulation of S5D-SRCRB expression was observed in in vitro and in vivo models of bacterial aggression, reinforcing the emerging view that CD, and specially IC, are important players in innate defense of the urinary tract against infection. Taken together, the results indicate that S5D-SRCRB is an integral component of the urogenital tract involved in innate immune functions.
S5D-SRCRB是一种新型的小鼠分泌性糖蛋白，属于古老且高度保守的富含半胱氨酸的清道夫受体蛋白受体超家族。现有证据表明，S5D-SRCRB与保守的微生物细胞壁成分以及一些内源性蛋白质相互作用，并呈现出受限的组织表达模式。本研究进一步分析了S5D-SRCRB在小鼠泌尿生殖道中的表达情况。在生精小管的精母细胞、尿道和膀胱的上皮表面以及主要来自髓质和乳头的肾小管中观察到了S5D-SRCRB的免疫组织化学染色。双重染色显示，S5D-SRCRB在肾集合管（CD）的主细胞（P）和闰细胞（IC）中均有表达。通过使用IC细胞分化的体外细胞模型，在终末分化的IC细胞的顶端边界观察到了S5D-SRCRB的优先表达。在肾脏和膀胱中也观察到了S5D-SRCRB与半乳糖凝集素-3（Gal-3）的共定位，但在睾丸中未观察到，这支持了同时进行的生化研究，证明了Gal-3与S5D-SRCRB之间的碳水化合物依赖性相互作用。此外，在细菌侵袭的体外和体内模型中观察到了S5D-SRCRB表达的上调，强化了一种新出现的观点，即CD，特别是IC，是尿路抵抗感染的固有防御中的重要参与者。综上所述，结果表明S5D-SRCRB是参与固有免疫功能的泌尿生殖道的一个组成部分。
