Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Pathobiology. 2012;79(1):34-44. doi: 10.1159/000332215. Epub 2012 Jan 12.
Sprouty, a common antagonist of fibroblast growth factor (FGF) and epidermal growth factor signaling, is a key player regulating tracheal branching and eye development in Drosophila. Four Sprouty homologs have been identified in vertebrates and all share a cysteine-rich region. However, the physiological function(s) of the individual Sprouty homologs is unknown. mRNA of Sprouty homologs is expressed during mouse lung development. In the present study, we investigated the immunolocalization of Sprouty proteins in rat lung at different stages of development.
Rabbit antibodies were raised against peptides derived from rat Sprouty-1 and Sprouty-2 and were used in Western blot analysis to determine Sprouty distribution in subcellular fractions (pellets and supernatant centrifuged at 5,000 and 20,000 g) and bronchoalveolar lavage fluid (BAL) from adult rat lungs or used in immunohistochemistry.
Western blot analysis revealed a 30-kDa Sprouty-1 band and a 34-kDa Sprouty-2 band in the supernatant and pellet fractions centrifuged at 20,000 g. BAL contained a band of approximately 16 kDa with Sprouty-1 antibody derived from proteolytic fragmentation of Sprouty-1. In embryonic day (E) 14 and E16 lungs, Sprouty-1 and Sprouty-2 were expressed both in epithelial and peripheral mesenchymal cells. In adult rat lung, bronchiolar and alveolar type II epithelial cells showed staining for both Sprouty-1 and Sprouty-2. Sprouty-1 expression was also seen in alveolar type I epithelial cells.
In light of the proximity of the distribution of Sprouty to that of FGF-10 (peripheral mesenchyme) and its receptor FGFR2IIIb (distal tubular epithelium) in lung development, and the finding that FGF-9, which is expressed in mesothelial cells, upregulates FGF-10, it appears that Sprouty expression in epithelial and mesenchymal cells during branching morphogenesis is closely related to signaling by FGF-9 and FGF-10.
芽殖蛋白（Sprouty）是一种常见的成纤维细胞生长因子（FGF）和表皮生长因子信号的拮抗剂，是调节果蝇气管分支和眼睛发育的关键因子。在脊椎动物中已经鉴定出 4 种 Sprouty 同源物，它们都具有富含半胱氨酸的区域。然而，单个 Sprouty 同源物的生理功能尚不清楚。Sprouty 同源物的 mRNA 在小鼠肺发育过程中表达。本研究探讨了 Sprouty 蛋白在不同发育阶段大鼠肺中的免疫定位。
用兔抗 Sprouty-1 和 Sprouty-2 肽的抗体进行 Western blot 分析，以确定 Sprouty 在亚细胞部分（在 5000g 和 20000g 离心的沉淀和上清液）和支气管肺泡灌洗液（BAL）中的分布，来自成年大鼠肺或用于免疫组织化学。
Western blot 分析显示，在 20000g 离心的上清液和沉淀部分中，Sprouty-1 出现 30kDa 条带，Sprouty-2 出现 34kDa 条带。BAL 含有一条约 16kDa 的带，用 Sprouty-1 抗体从 Sprouty-1 的蛋白水解片段中衍生而来。在胚胎第 14 天（E14）和 E16 肺中，Sprouty-1 和 Sprouty-2 在上皮细胞和周围间质细胞中均有表达。在成年大鼠肺中，细支气管和肺泡 II 型上皮细胞显示出 Sprouty-1 和 Sprouty-2 的染色。Sprouty-1 表达也见于肺泡 I 型上皮细胞。
鉴于 Sprouty 与 FGF-10（周围间质）及其受体 FGFR2IIIb（远端管状上皮）在肺发育中的分布接近，以及表达于间皮细胞的 FGF-9 上调 FGF-10 的发现，在分支形态发生过程中，上皮细胞和间充质细胞中 Sprouty 的表达似乎与 FGF-9 和 FGF-10 的信号密切相关。
