Huang W, Lee D, Yang Z, Casley D, Throsby M, Copolov D L, Johnston C, Lim A T
Neuroendocrine Laboratory, Royal Park Hospital, Parkville, Victoria, Australia.
Endocrinology. 1992 Aug;131(2):919-24. doi: 10.1210/endo.131.2.1386304.
Atrial natriuretic peptide (ANP), a 28-amino acid peptide, is produced and secreted by cardiac atriocytes to modulate cardiovascular and renal functions. We report here the production of ANP-(5-28) and its 15K mol wt (M(r)) presumptive precursors by cytotrophoblasts of rat placentae. Placental tissues were collected from Sprague-Dawley fetal rats on days 12, 16, 18, and 20 of gestation and acid extracted for immunoreactive (ir) ANP assay. The contents of placental irANP increased over the course of fetal growth, with the highest amount (mean +/- SE, 1083 +/- 125 pg/tissue; n = 7) found near term. Sephadex G-50 gel chromatographic profiles of the placental extract revealed a major peak of irANP coeluted with the 3K M(r) of synthetic rat (r) ANP-(1-28) and a minor peak in the position consistent with that of 15K M(r). HPLC analysis of the 3K M(r) species showed a single peak of immunoreactivity, which eluted with a retention time similar to that of rANP-(5-28). In placental sections, irANP and pro-ANP mRNA were localized by immunoperoxidase staining and colorimetric in situ hybridization in a subpopulation of placental cytotrophoblasts, but not in syncytiotrophoblasts or chorionic cells. Northern blot analysis showed a single band of pro-ANP mRNA in rat placental tissues similar in size to that found in the heart (approximately 0.85 kilobases), with the highest level of pro-ANP mRNA signal detected in the placentae of 16-day gestation fetuses. Our findings suggest that ANP is expressed and produced by a small population of rat placental cytotrophoblasts and that the 15K M(r) precursor peptide is extensively processed into the N-terminal-truncated form of ANP-(5-28) in the tissue.
心房利钠肽（ANP）是一种由28个氨基酸组成的肽，由心脏心房肌细胞产生并分泌，用于调节心血管和肾功能。我们在此报告大鼠胎盘的细胞滋养层细胞产生ANP-(5-28)及其推定的15K分子量（M(r)）前体。在妊娠第12、16、18和20天从Sprague-Dawley胎鼠收集胎盘组织，并进行酸提取以进行免疫反应性（ir）ANP测定。胎盘irANP的含量在胎儿生长过程中增加，在足月时含量最高（平均值±标准误，1083±125 pg/组织；n = 7）。胎盘提取物的Sephadex G-50凝胶色谱图谱显示，irANP的一个主要峰与合成大鼠（r）ANP-(1-28)的3K M(r)共洗脱，在与15K M(r)一致的位置有一个小峰。对3K M(r)物质的HPLC分析显示单一免疫反应性峰，其洗脱保留时间与rANP-(5-28)相似。在胎盘切片中，通过免疫过氧化物酶染色和比色原位杂交在胎盘细胞滋养层细胞亚群中定位irANP和前ANP mRNA，但在合体滋养层细胞或绒毛膜细胞中未定位。Northern印迹分析显示大鼠胎盘组织中前ANP mRNA的单一条带，其大小与心脏中发现的相似（约0.85千碱基），在妊娠16天胎儿的胎盘中检测到的前ANP mRNA信号水平最高。我们的研究结果表明，ANP由一小部分大鼠胎盘细胞滋养层细胞表达和产生，并且15K M(r)前体肽在组织中被广泛加工成N端截短形式的ANP-(5-28)。
