Nephrin, podocin, CD2AP, and a-actinin-4 are important podocyte proteins that help maintain the integrity of the slit diaphragm and prevent proteinuria. Studies have shown that angiotensin-converting enzyme inhibitors, glucocorticoids, and all-trans retinoic acid (ATRA) have antiproteinuric effects. However, it is still unclear whether these drugs, with different pharmacological mechanisms, lead to a reduction in proteinuria by changing the expression and distribution of these important podocyte proteins. In this study, changes in the expression and distribution of nephrin, podocin, CD2AP, and a-actinin-4 were dynamically detected in Adriamycin-induced nephrotic (ADR) rats treated with three different drugs: lisinopril, prednisone, and ATRA. Nephropathy was induced by an intravenous injection of Adriamycin. After Adriamycin injection, rats received lisinopril, prednisone, and ATRA treatment, respectively. Renal tissues were collected at Days 3, 7, 14, and 28. The distribution and the expression of messenger RNA and protein of nephrin, podocin, CD2AP, and a-actinin-4 were detected by indirect immunofluorescence, real-time polymerase chain reaction, and Western blotting, respectively. With the intervention of lisinopril, prednisone, and ATRA, changes in the expression of nephrin, podocin, and CD2AP were diverse, which was different from that detected in ADR rats. After lisinopril and prednisone intervention, podocin exhibited prominent earlier changes compared with those of nephrin and CD2AP, whereas CD2AP showed more prominent changes after ATRA intervention. There was no change in the expression of a-actinin-4 molecule. In summary, we conclude that the antiproteinuric effects of lisinopril, prednisone, and ATRA were achieved by changes in the expression and distribution of the important podocyte molecules nephrin, podocin, CD2AP, and a-actinin-4. The pattern in the change of podocyte molecules after lisinopril and prednisone intervention was similar, but the pattern in the change of podocyte molecules after ATRA intervention was different from that of lisinopril or prednisone intervention.

The effects of the combined use of angiotensin converting enzyme inhibitor (ACEI) benazepril and angiotensin Ⅱ type 1 receptor antagonist (AT1RA) valsartan on apoptosis and the expression of apoptosis2related proteins Fas and FasL in the kidney of rats with adriamycin2induced nephritic glomerulosclerosis was investigated. Uninephrectomy and the injection of adriamycin induced the rat model of glomerulosclerosis. Benazepril (6 mg/ kg), valsantan (20 mg/ kg), or benazepril (3 mg/ kg) plus valsantan (20 mg/ kg) was respectively delivered daily by gavage to the rats in three treatment groups for 12 weeks. Apoptosis was examined by means of terminal-deoxynucleotidyl transferase mediated d-UTP nick end labeling ( TUNEL). Immunohistochemistry was adopted to detect the expression of Fas and FasL. Software of pathological analysis quantitated the levels of Fas and FasL. The results showed that as compared with those in the control group, the kidneys in the model group had more severe glomerulosclerosis, much more apoptotic cells and higher levels of expression of Fas and FasL. The degree of glomerulosclerosis, the number of apoptotic cells and the levels of expression of Fas and FasL were reduced by benazepril and valsartan. The combined use of benazepril and valsartan had the best therapeutic effect. It was concluded that benazepril and valsartan could suppress the excessive apoptosis of kidney cells by lowering the expression of the apoptosis-related proteins Fas and FasL, so as to postpone the process of glomerulosclerosis. The combined use of benazepril and valsartan has better therapeutic effect .

The abnormality of a single podocyte molecule, caused by a single gene mutation, such as NPHS1, NPHS2, CD2AP, and ACTN4, can lead to the hereditary/congenital nephrotic syndromes (NS). Further studies suggested that more than one podocyte molecule were together involved in acquired or experimental NS. However, we do not know much on the relationship among these podocyte molecules, and the molecular response induced by the change of each podocyte protein to the remaining ones. We respectively knockdown the nephrin, podocin, CD2AP, or a-actinin-4 mRNA by using reconstructed RNA interference vector – psiRNA-hH1GFPzeo in mouse podocyte clone. The molecular behavior or response was revealed by the quantitative expression both at mRNA and protein levels with RT-PCR and Western blot, and by the molecular distribution detected with confocal microscopy. With nephrin knockdown, only CD2AP increased, whereas podocin showed no change. Contrarily, with podocin or CD2AP knockdown, nephrin decreased, while CD2AP or podocin increased. Nephrin, podocin, or CD2AP knockdown did not change the expression of a-actinin-4, whereas a-actinin-4 knockdown begetted the reduction of nephrin, and the increment of podocin and CD2AP. The redistributions of nephrin, podocin, and CD2AP were revealed around a predominant nuclear staining compared with the membrane surface staining in the control podocytes. Our data imply that the response between the four podocyte molecules is very complicated and evidently different. There is not always an interaction between podocyte molecules. The normal localization of podocyte molecules would depend on their normal expression quantity and the molecular reactions between them.

蛋白尿是肾脏疾病最常见的临床症状之一。近年来，Nephrin、Podocin、CD2AP和α2actinin24等重要足细胞结构蛋白和细胞骨架分子的确立，为肾小球性蛋白尿发生机制的研究提供了新的思路[ 1～5 ] 。然而，由于蛋白尿临床病理以及遗传背景的异质性，其发生机制尤其是分子机制仍未完全阐明。2005年，Winn和Reiser研究组又确定了一个导致家族性局灶节段性肾小球硬化( FSGS ) 的基因——TRPC6[ 6， 7 ] ，其编码蛋白瞬时受体电位阳离子通道蛋白( transient recep tor potential cation channel 6，TRPC6)是一个非选择性阳离子通道，新近发现其在足细胞也有表达，而且和裂孔隔膜分子Nephrin以及Podocin间存在相互作用，这一发现将足细胞结构蛋白和离子通道联系起来，丰富了足细胞分子网络，拓宽了对肾小球性蛋白尿发生机制的认识。因此，认识该基因、筛查可能存在的突变以及进一步研究该基因的功能将对探讨蛋白尿发生的分子机制以及防治蛋白尿具有新的意义。本文着重介绍TRPC6突变致家族性FSGS，同时对TRPC6在肾脏疾病领域的研究也作一概述。

目的从足细胞分子的角度探讨抗蛋白尿药物作用的细胞分子机制。方法建立阿霉素肾病大鼠模型。注射阿霉素后次日分别给予利生普利、泼尼松以及全反式维甲酸（ATRA）干预蛋白尿。注射阿霉素后第3、7、14、28天每组处死6只大鼠，留取。肾脏标本。应用间接免疫荧光染色、实时PCR、Western印迹分别检测各个时间点nephrin、podocin、CD2相关蛋白（AP）、α辅肌动蛋白（actinin）-4的分布、mRNA和蛋白表达量的变化。应用免疫沉淀检测nephrin与podocin、nephfin与CD2AP分子间作用以及nephrin磷酸化水平。结果与对照组相比，第14天时肾病组尿蛋白显著增加（P < 0.01）。与肾病组相比，利生普利、泼尼松和ATRA干预后均显著降低了蛋白尿（P < 0.05），减轻了足突融合。通过分析不同时间点足细胞分子的表达．显示3种干预药物均引起了nephrin、podocin、CD2AP表达的变化，维持了正常的nephrin磷酸化水平，而且利生普利和泼尼松首先抑制了podocin分子，而ATRA首先抑制了CD2AP分子的异常变化。与此同时，nephrin、podocin、CD2AP和α-actinin-4分子的分布在干预后也趋于正常。此外．无论在肾病组还是干预组大鼠，nephrin与podocin、nephtin与CD2AP分子间一直保持着共沉淀关系。结论利生普利、泼尼松和ATRA都通过稳定重要的足细胞分子nephrin、podocin、CD2AP来发挥它们的抗蛋白尿作用。