肾素(原)受体在大鼠肾小球系膜细胞和肾脏的表达

近年发现的肾素（原）受体（renin／prorenin receptor,RnR）已被证明具有生物学功能,在心、肾及多种细胞表达。本文旨在观察RnR在体外培养的大鼠肾小球系膜细胞（mesangial cells,MCs）和肾脏中是否表达,及其表达的细胞部位,并用RnR的多肽阻断剂肾素原“柄区肽”（handle region peptide,HRP）与RnR结合后观察受体复合物进入细胞的过程与定位。结果显示,RnR主要存在于大鼠肾脏皮质肾小球系膜区和体外培养的MCs的细胞核周围胞浆和细胞膜。将FITC标记的HRP（FITC-HRP）加入细胞培养液后30S到30min期间,可观察到FITC-HRP由培养液转移到胞浆内并进入细胞核。用免疫荧光和激光共聚焦技术观察到,HRP与RnR的共定位主要位于细胞膜和细胞核周围胞浆;在30min时,一部分HRP已进入细胞核,而RnR没有进入细胞核内,仍主要位于细胞核周围胞浆。上述结果提示,RnR与其配基结合后进入细胞内并发挥生物学效应。

Expression of renin/prorenin receptor in rat kidney and cultured mesangial cells

The renin/prorenin receptor (RnR) has recently been cloned and demonstrated to exist in different cells in the cardiovascular and renal systems, playing an important role in physiological and pathophysiological situations. In the present study, we used immunofluorescence method to identify whether and where the RnR expressed in cultured rat renal mesangial cells (MCs) and rat kidney. By using the prorenin handle region peptide (HRP) as a decoy peptide of the RnR, we observed the distribution of the HRP-RnR complex in the MCs. Our results showed that the RnR was localized in the perinuclear zone and plasma membrane of the MCs. At the organ level, the RnR was observed in the mesangium of cortical glomeruli in rat kidney. The FITC-labeled HRP (FITC-HRP) translocated from cell culture medium into the cytoplasm within 30 s. Colocalization of the HRP and RnR was observed mainly on the cell membrane and in the perinuclear zone of cytoplasm by using immunofluorescence and confocal microscopy. At 30 min the FITC-HRP was mainly observed in the nucleus while the RnR remained in the perinuclear zone of cytoplasm. Taken together, our results confirm the expression of RnR in the renal MCs. It is suggested that internalization of the RnR after binding with its ligand is at least one of the pathways through which the RnR exerts its biological actions.