Wolff Natascha A, Thies Karen, Kuhnke Nicola, Reid Glen, Friedrich Björn, Lang Florian, Burckhardt Gerhard
Center for Physiology and Pathophysiology, Georg August University, Göttingen, Germany.
J Am Soc Nephrol. 2003 Aug;14(8):1959-68. doi: 10.1097/01.asn.0000079040.55124.25.
Organic anion transport in intact renal proximal tubule cells in animal model systems is downregulated by treatments that activate protein kinase C (PKC). How this downregulation is achieved is not yet known. Stimulation of PKC with sn-1,2-dioctanoylglycerol resulted in strong inhibition of p-aminohippurate transport mediated by the cloned human organic anion transporter 1 (hOAT1) expressed in Xenopus oocytes and HEK293 cells, as well as hOAT1 internalization in both expression systems. The sn-1,2-dioctanoylglycerol-induced transport inhibition was partially prevented by staurosporine. It was independent of the conserved canonical PKC consensus sites in hOAT1, however, and was unaffected by agents that destabilize actin filaments or microtubules, which altered baseline hOAT1-mediated p-aminohippurate uptake activity in oocytes. It is concluded that PKC-induced hOAT1 downregulation is achieved through carrier retrieval from the cell membrane and does not involve phosphorylation of the predicted classic hOAT1 PKC consensus sites.
在动物模型系统中，完整肾近端小管细胞中的有机阴离子转运可被激活蛋白激酶C（PKC）的处理下调。这种下调是如何实现的尚不清楚。用sn-1,2-二辛酰甘油刺激PKC导致在非洲爪蟾卵母细胞和人胚肾293细胞（HEK293）中表达的克隆人有机阴离子转运体1（hOAT1）介导的对氨基马尿酸转运受到强烈抑制，以及在这两种表达系统中hOAT1内化。sn-1,2-二辛酰甘油诱导的转运抑制被星形孢菌素部分阻止。然而，它不依赖于hOAT1中保守的典型PKC共有序列，并且不受破坏肌动蛋白丝或微管的试剂的影响，这些试剂改变了卵母细胞中基线hOAT1介导的对氨基马尿酸摄取活性。得出的结论是，PKC诱导的hOAT1下调是通过从细胞膜回收载体实现的，并且不涉及预测的经典hOAT1 PKC共有序列的磷酸化。
