Landry C, Huet C, Mangeat P, Sahuquet A, Louvard D, Crine P
Département de Biochimie, Université de Montréal, Québec, Canada.
Differentiation. 1994 Apr;56(1-2):55-65. doi: 10.1046/j.1432-0436.1994.56120055.x.
Neutral endopeptidase (Endopeptidase 24.11; NEP; neprilysin), an integral membrane protein, and villin, a major microvillar cytoskeletal actin-binding protein, are both typically associated with brush border epithelia. In this study, cRNA probes were hybridized in situ to investigate the expression of NEP and villin genes in embryo and adult mouse enterocytes. During development, villin mRNAs were easily detected in the immature digestive tract well before establishment of the brush border. In 17-day-old embryos, a transient elevation of villin mRNA occurred just prior to a dramatic increase in microvilli length and density. NEP only appeared by day 17 as the embryonic gut began to become functional. It therefore appears that the onset of transcription of specialized cytoskeletal proteins from the brush border preceded that of intrinsic membrane-bound enzyme from microvilli. In the adult intestinal fold, both mRNAs were expressed along the whole length of the villus with maximal expression at its base. In contrast, both proteins were uniformly expressed along the whole crypt-villus axis. Quantitative analysis revealed an asymmetric intracellular distribution of both mRNAs that were differentially polarized in the apical cytoplasm of enterocytes.
中性内肽酶（内肽酶24.11；NEP；肾素-血管紧张素系统羧基肽酶）是一种整合膜蛋白，而绒毛蛋白是一种主要的微绒毛细胞骨架肌动蛋白结合蛋白，二者通常都与刷状缘上皮相关。在本研究中，采用原位杂交cRNA探针来研究NEP和绒毛蛋白基因在胚胎和成年小鼠肠细胞中的表达。在发育过程中，早在刷状缘形成之前，就能在未成熟的消化道中轻松检测到绒毛蛋白mRNA。在17日龄胚胎中，绒毛蛋白mRNA在微绒毛长度和密度急剧增加之前出现短暂升高。NEP直到第17天才出现，此时胚胎肠道开始具备功能。因此，似乎刷状缘特化细胞骨架蛋白的转录起始早于微绒毛内在膜结合酶的转录起始。在成年肠皱襞中，两种mRNA在绒毛全长均有表达，在其基部表达量最高。相反，两种蛋白质在整个隐窝-绒毛轴上均匀表达。定量分析显示，两种mRNA在肠细胞顶端细胞质中呈不对称的细胞内分布，且极性不同。
