کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2166549 | 1091865 | 2009 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Activation of the Ca2+-sensing receptor stimulates the activity of the epithelial Ca2+ channel TRPV5 Activation of the Ca2+-sensing receptor stimulates the activity of the epithelial Ca2+ channel TRPV5](/preview/png/2166549.png)
The extracellular Ca2+-sensing receptor (CaR) is a key-player in plasma Ca2+ homeostasis. It is essentially expressed in the parathyroid glands and along the kidney nephron. The distal convoluted tubules (DCT) and connecting tubules (CNT) in the kidney are involved in active Ca2+ reabsorption, but the function of the CaR has remained unclear in these segments. Here, the Ca2+-selective Transient Receptor Potential Vanilloid-subtype 5 channel (TRPV5) determines active Ca2+ reabsorption by forming the apical entry gate. In this study we show that the CaR and TRPV5 co-localize at the luminal membrane of DCT/CNT. Furthermore, by patch-clamp and Fura-2-ratiometric measurements we demonstrate that activation of the CaR leads to elevated TRPV5-mediated currents and increases intracellular Ca2+ concentrations in cells co-expressing TRPV5 and CaR. Activation of CaR initiated a signaling cascade that activated phorbol-12-myristate-13-acetate (PMA)-insensitive protein kinase C (PKC) isoforms. Importantly, mutation of two putative PKC phosphorylation sites, S299 and S654, in TRPV5 prevented the stimulatory effect of CaR activation on channel activity, as did a dominant negative CaR construct, CaRR185Q. Interestingly, the activity of TRPV6, TRPV5′ closest homologue, was not affected by the activated CaR. We conclude that activation of the CaR stimulates TRPV5-mediated Ca2+ influx via a PMA-insensitive PKC isoform pathway.
Journal: Cell Calcium - Volume 45, Issue 4, April 2009, Pages 331–339