Role of PKCalpha in feedback regulation of Na(+) transport in an electrically tight epithelium.
Role of PKCalpha in feedback regulation of Na(+) transport in an electrically tight epithelium.
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PKCα 在电致密的上皮细胞中 Na(+) 运输的反馈调节中的作用。
DOI：
10.1152/ajpcell.00142.2002
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Bengrine,Abderrahmane
中科院分区：
文献类型：
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作者：
Awayda,MouhamedS;Platzer,JustinD;Reger,RoxanneL;Bengrine,Abderrahmane
长期以来，人们已经知道，在电紧密上皮细胞中的Na+通道是由稳态机制调节的，该稳态机制维持稳定状态，并允许新水平的转运在受到攻击的细胞中得以维持。对这些过程中涉及的潜在途径知之甚少。除了短期效应外，最近的证据还表明PKC在蛋白质水平上参与上皮Na+通道（ENaC）的长期调节（40）。为了确定ENaC的刺激是否涉及PKC水平的反馈调节，我们利用蛋白质印迹分析来确定极化A6上皮细胞中PKC亚型的分布。我们发现在常规（α和γ）、新型（δ、η和ε）和非典型（ι、λ和ε）组中存在PKC亚型。醛固酮对Na+转运的稳态刺激伴随着胞质和膜组分中PKCα蛋白水平的特异性降低。同样，用不带电荷的阿米洛利类似物（CDPC）过夜治疗，这是一种通过反馈调节刺激Na+转运的方法，也降低了PKCα水平。这些效应是累加的，表明在PKCα水平上会聚的单独机制。北方印迹分析表明，这些作用不伴随PKCα mRNA水平的变化。我们建议，这可能代表了一种新的监管反馈机制，必要的持续增加的Na+运输。
It has long been known that Na+channels in electrically tight epithelia are regulated by homeostatic mechanisms that maintain a steady state and allow new levels of transport to be sustained in hormonally challenged cells. Little is known about the potential pathways involved in these processes. In addition to short-term effect, recent evidence also indicates the involvement of PKC in the long-term regulation of the epithelial Na+channel (ENaC) at the protein level (40). To determine whether stimulation of ENaC involves feedback regulation of PKC levels, we utilized Western blot analysis to determine the distribution of PKC isoforms in polarized A6 epithelia. We found the presence of PKC isoforms in the conventional (α and γ), novel (δ, η, and ε), and atypical (ι, λ, and ζ) groups. Steady-state stimulation of Na+transport with aldosterone was accompanied by a specific decrease of PKCα protein levels in both the cytoplasmic and membrane fractions. Similarly, overnight treatment with an uncharged amiloride analog (CDPC), a procedure that through feedback regulation causes a stimulation of Na+transport, also decreased PKCα levels. These effects were additive, indicating separate mechanisms that converge at the level of PKCα. These effects were not accompanied by changes of PKCα mRNA levels as determined by Northern blot analysis. We propose that this may represent a novel regulatory feedback mechanism necessary for sustaining an increase of Na+transport.