Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg 69120, Germany; Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672, United States.
Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672, United States; Department of Pharmaceutical Sciences, University of Basel, Basel 4056, Switzerland.
Aquat Toxicol. 2022 Nov;252:106314. doi: 10.1016/j.aquatox.2022.106314. Epub 2022 Sep 25.
ABC export proteins including Multidrug resistance-related protein 2 (Mrp2) serve as detoxification mechanism in renal proximal tubules due to active transport of xenobiotics and metabolic waste products into primary urine. The environmental pollutants aluminum and arsenic interfere with a multitude of regulatory mechanisms in the body and here their impact on ABC transporter function was studied. NaAsO but not AlCl rapidly stimulated Mrp2-mediated Texas Red (TR) transport in isolated renal proximal tubules from killifish, a well-established laboratory model for the determination of efflux transporter activity by utilizing fluorescent substrates for the ABC transporters of interest and confocal microscopy followed by image analysis. This observed stimulation remained unaffected by the translation inhibitor cycloheximide (CHX), but it was abrogated by antagonists and inhibitors of the endothelin receptor type B (ET)/nitric oxide synthase (NOS)/protein kinase C (PKC) signaling pathway. NaAsO-triggered effects were abolished as a consequence of PKCα inhibition through Gö6976 and PKCα inhibitor peptide C2-4. Phosphatidylinositol 3-kinase (PI3K) inhibitor LY 294,002 as well as the mammalian target of rapamycin (mTOR) inhibitor rapamycin suppressed NaAsO-triggered stimulation of luminal TR transport. In addition, the stimulatory effect of NaAsO was abolished by GSK650394, an inhibitor of serum- and glucocorticoid-inducible kinase 1 (SGK1), which is an important downstream target. Environmentally relevant concentrations of NaAsO further stimulated transport function of P-glycoprotein (P-gp), Multidrug resistance-related protein 4 (Mrp4) and Breast cancer resistance protein (Bcrp) while AlCl was ineffective. To our knowledge, this is the first report engaging in the impact of NaAsO on efflux transporter signaling and it may contribute to the understanding of defense mechanisms versus this worrying pollutant.
ABC 出口蛋白，包括多药耐药相关蛋白 2（Mrp2），作为肾脏近端小管中的解毒机制，通过将外源性物质和代谢废物主动转运到初级尿中。环境污染物铝和砷干扰了体内多种调节机制，在此研究了它们对 ABC 转运蛋白功能的影响。NaAsO 而不是 AlCl 快速刺激来自食蚊鱼（一种用于利用荧光底物测定感兴趣的 ABC 转运体活性的成熟实验室模型）分离的肾脏近端小管中 Mrp2 介导的 Texas Red（TR）转运，随后进行共焦显微镜检查和图像分析。这种观察到的刺激不受翻译抑制剂环己酰亚胺（CHX）的影响，但被内皮素受体 B（ET）/一氧化氮合酶（NOS）/蛋白激酶 C（PKC）信号通路的拮抗剂和抑制剂所阻断。NaAsO 触发的效应由于 PKCα 通过 Gö6976 和 PKCα 抑制剂肽 C2-4 的抑制而被消除。磷酸肌醇 3-激酶（PI3K）抑制剂 LY 294,002 以及哺乳动物雷帕霉素靶蛋白（mTOR）抑制剂 rapamycin 抑制了 NaAsO 触发的管腔 TR 转运的刺激。此外，NaAsO 的刺激作用被 GSK650394 消除，GSK650394 是一种血清和糖皮质激素诱导激酶 1（SGK1）抑制剂，SGK1 是一个重要的下游靶标。环境相关浓度的 NaAsO 进一步刺激了 P-糖蛋白（P-gp）、多药耐药相关蛋白 4（Mrp4）和乳腺癌耐药蛋白（Bcrp）的转运功能，而 AlCl 则没有效果。据我们所知，这是首次报道 NaAsO 对外排转运蛋白信号的影响，这可能有助于理解针对这种令人担忧的污染物的防御机制。
