PAPPA2 is a metalloproteinase which cleaves insulin-like growth factor binding protein (IGFBP)-3 and IGFBP-5, and its role in pregnancy and postnatal growth is primarily studied. Using exclusion mapping, we reported a subcongenic (26-P) rat where a 0.71-Mbp region containing the pregnancy-associated plasma protein a2 (Pappa2) allele of salt-insensitive Brown Norway (BN) was introgressed into Dahl saltsensitive (SS) genetic background, resulting in the reduction of salt sensitivity. Pappa2 was differentially expressed in the adult kidney of 26-P and SS rats. Here, the expression and cellular localization of Pappa2 in embryonic and postnatal kidneys of 26-P and SS rats were examined. Pappa2 mRNA expression was 5-fold higher in the embryonic kidney (day 20.5) of the 26-P rat compared with the SS rat. Pappa2 mRNA expression progressively increased with the development of kidney, reaching a peak at postnatal day 5 before trending downward in subsequent stages of development in both strains. At all tested time points, Pappa2 remained higher in the 26-P compared with the SS rat kidney. Immunohistochemistry studies localized PAPPA2 in the ureteric bud (UB) and distal part of S-shaped body. PAPPA2 was colocalized with IGFBP-5 in the UB and Na⁺/K⁺/2Cl⁻ cotransporter–stained tubules, respectively. Future studies are needed to determine the role of Pappa2 in kidney development and mechanistic pathways involved in this process.

PAPPA2是一种金属蛋白酶，可切割胰岛素样生长因子结合蛋白（IGFBP）-3和IGFBP-5，并且主要研究其在妊娠和产后生长中的作用。使用排除映射，我们报告了一个亚同基因（26-P）大鼠，其中0.71 Mbp的区域包含盐敏感性布朗挪威（BN）的与怀孕相关的血浆蛋白a2（Pappa2）等位基因，进入达尔盐敏感性（SS）遗传背景，导致盐敏感性降低。Pappa2在26-P和SS大鼠的成年肾脏中差异表达。在这里，检查了Pappa2在26-P和SS大鼠的胚胎和出生后肾脏中的表达和细胞定位。帕帕2与SS大鼠相比，26-P大鼠的胚胎肾脏（第20.5天）的mRNA表达高5倍。Pappa2 mRNA表达随着肾脏的发展而逐渐增加，在出生后第5天达到峰值，然后在这两个菌株的后续发育阶段均趋于下降。在所有测试时间点，与SS大鼠肾脏相比，Pappa2在26-P中保持较高水平。免疫组织化学研究将PAPPA2定位于输尿管芽（UB）和S形体的远端。PAPPA2用IGFBP-5中的UB和Na共定位⁺ / K ⁺ / 2CL ^-协同转运蛋白染色的小管，分别。需要进一步的研究以确定Pappa2的作用 肾脏发育和此过程涉及的机制途径。