Insulin potentiates AVP-induced AQP2 expression in cultured renal collecting duct principal cells
Insulin potentiates AVP-induced AQP2 expression in cultured renal collecting duct principal cells
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DOI：
10.1152/ajprenal.00180.2004
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发表时间：
2005-02-01
影响因子：
4.2
通讯作者：
Féraille, E
中科院分区：
文献类型：
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作者：
Bustamante, M;Hasler, U;Féraille, E
在肾集合管（CD）中，水重吸收依赖于主细胞顶膜中水通道蛋白2（AQP 2）的存在。AQP 2的表达和亚细胞再分配受AVP的调控。一些实验证据表明，额外的激素因素，包括胰岛素，也可能控制AQP 2的表达，从而CD水渗透性。我们先前已经表明AVP诱导培养的小鼠mpkCCD（cl 4）CD主细胞中的内源性AQP 2表达（23）。在本研究中，我们研究了胰岛素对mpkCCDcl 4细胞中AQP 2表达的影响。在过滤器上生长的细胞的基础培养基中加入胰岛素略微增加了AQP 2 mRNA和蛋白的表达，而胰岛素增强了AVP的作用。胰岛素增强AVP诱导的AQP 2表达可被转录抑制剂放线菌素D所消除。AVP洗脱条件下和/或氯喹（一种溶酶体降解抑制剂）存在下AQP 2蛋白表达的分析显示，胰岛素未显著改变AQP 2蛋白降解。抑制ERK、p38激酶和磷脂酰肌醇3 '-激酶（PI 3-激酶）活性可阻止胰岛素诱导的AQP 2表达刺激，而抑制PKC则无影响。总之，我们的结果表明，胰岛素增加AQP 2蛋白的表达主要是通过增加AQP 2 mRNA水平在培养的mpkCCDcl 4细胞。这种效应很可能依赖于响应MAPK和PI 3-激酶激活的AQP 2基因转录增加。
In the renal collecting duct ( CD), water reabsorption depends on the presence of aquaporin-2 (AQP2) in the apical membrane of principal cells. AQP2 expression and subcellular repartition are under the control of AVP. Some pieces of experimental evidence indicate that additional hormonal factors, including insulin, may also control AQP2 expression and thereby CD water permeability. We have previously shown that AVP induces endogenous AQP2 expression in cultured mouse mpkCCD(cl4) CD principal cells (23). In the present study, we investigated the effect of insulin on AQP2 expression in mpkCCDcl4 cells. Addition of insulin to the basal medium of cells grown on filters slightly increased AQP2 mRNA and protein expression, whereas insulin potentiated the effect of AVP. The potentiation of AVP-induced AQP2 expression by insulin was abolished by actinomycin D, a transcriptional inhibitor. Analysis of AQP2 protein expression under conditions of AVP washout and/or in the presence of chloroquine, a lysosomal degradation inhibitor, revealed that insulin did not significantly alter AQP2 protein degradation. Inhibition of ERK, p38 kinase, and phosphatidylinositol 3'-kinase (PI 3-kinase) activities prevented the insulin-induced stimulation of AQP2 expression, whereas inhibition of PKC has no effect. Taken together, our results indicate that insulin increased AQP2 protein expression mostly through increased AQP2 mRNA levels in cultured mpkCCDcl4 cells. This effect most likely relies on increased AQP2 gene transcription in response to MAPK and PI 3-kinase activation.