Adragna N C, Ferrell C M, Zhang J, Di Fulvio M, Temprana C F, Sharma A, Fyffe R E W, Cool D R, Lauf P K
Cell Biophysics Group, Wright State University School of Medicine, Dayton, OH 45435, USA.
Acta Physiol (Oxf). 2006 May-Jun;187(1-2):125-39. doi: 10.1111/j.1748-1716.2006.01560.x.
The K+-Cl- cotransport (COT) regulatory pathways recently uncovered in our laboratory and their implication in disease state are reviewed. Three mechanisms of K+-Cl- COT regulation can be identified in vascular cells: (1) the Li+-sensitive pathway, (2) the platelet-derived growth factor (PDGF)-sensitive pathway and (3) the nitric oxide (NO)-dependent pathway. Ion fluxes, Western blotting, semi-quantitative RT-PCR, immunofluorescence and confocal microscopy were used. Li+, used in the treatment of manic depression, stimulates volume-sensitive K+-Cl- COT of low K+ sheep red blood cells at cellular concentrations <1 mM and inhibits at >3 mM, causes cell swelling, and appears to regulate K+-Cl- COT through a protein kinase C-dependent pathway. PDGF, a potent serum mitogen for vascular smooth muscle cells (VSMCs), regulates membrane transport and is involved in atherosclerosis. PDGF stimulates VSM K+-Cl- COT in a time- and concentration-dependent manner, both acutely and chronically, through the PDGF receptor. The acute effect occurs at the post-translational level whereas the chronic effect may involve regulation through gene expression. Regulation by PDGF involves the signalling molecules phosphoinositides 3-kinase and protein phosphatase-1. Finally, the NO/cGMP/protein kinase G pathway, involved in vasodilation and hence cardiovascular disease, regulates K+-Cl- COT in VSMCs at the mRNA expression and transport levels. A complex and diverse array of mechanisms and effectors regulate K+-Cl- COT and thus cell volume homeostasis, setting the stage for abnormalities at the genetic and/or regulatory level thus effecting or being affected by various pathological conditions.
本文综述了我们实验室最近发现的钾氯共转运体（COT）调控途径及其在疾病状态中的意义。在血管细胞中可识别出三种钾氯共转运体调控机制：（1）锂敏感途径；（2）血小板衍生生长因子（PDGF）敏感途径；（3）一氧化氮（NO）依赖途径。研究采用了离子通量测定、蛋白质印迹法、半定量逆转录聚合酶链反应、免疫荧光和共聚焦显微镜技术。用于治疗躁狂抑郁症的锂，在细胞内浓度<1 mM时刺激低钾绵羊红细胞的容积敏感型钾氯共转运体，而在>3 mM时则起抑制作用，导致细胞肿胀，且似乎通过蛋白激酶C依赖途径调控钾氯共转运体。PDGF是血管平滑肌细胞（VSMC）的一种强效血清促有丝分裂原，可调节膜转运并参与动脉粥样硬化。PDGF通过PDGF受体，以时间和浓度依赖的方式，急性和慢性地刺激VSMC的钾氯共转运体。急性效应发生在翻译后水平，而慢性效应可能涉及通过基因表达进行的调控。PDGF的调控涉及信号分子磷脂酰肌醇3激酶和蛋白磷酸酶-1。最后，参与血管舒张及心血管疾病的NO/cGMP/蛋白激酶G途径，在mRNA表达和转运水平调控VSMC中的钾氯共转运体。一系列复杂多样的机制和效应器调控着钾氯共转运体，进而维持细胞容积稳态，这为遗传和/或调控水平的异常创造了条件，从而影响各种病理状况或受其影响。
