Transport by the (Na+,K+) ATPase: modulation by differentiation inducers and inhibition of protein synthesis in the MDCK kidney epithelial cell line.
Transport by the (Na+,K+) ATPase: modulation by differentiation inducers and inhibition of protein synthesis in the MDCK kidney epithelial cell line.
复制标题
(Na ,K ) ATP 酶转运：通过分化诱导剂进行调节并抑制 MDCK 肾上皮细胞系中的蛋白质合成。
DOI：
10.1002/jcp.1041230317
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发表时间：
1985
影响因子：
5.6
通讯作者：
Lever,JE
中科院分区：
文献类型：
--
作者：
Kennedy,BG;Lever,JE
MDCK 肾上皮细胞培养物暴露于分化诱导剂六亚甲基双乙酰胺 (HMBA) 24 小时，显示每个 (Na+, K+)-ATP 酶分子的转运活性（周转数）降低 50%，但泵位点数量不变（Kennedy 和 Lever，1984）。 10 μM 放线菌酮或 2 μM 依米丁对蛋白质合成的抑制作用阻断了 HMBA 对 Na+/K+ 泵效率的抑制作用，这些抑制作用通过测量 [3H]-哇巴因与完整细胞的结合、去污剂激活的细胞提取物的 (Na+, K+) ATP 酶活性以及哇巴因敏感的 Rb+ 摄取来评估。在没有诱导剂处理的情况下，蛋白质合成的抑制使Na+/K+泵周转数增加两倍，同时将每个细胞的Na+/K+泵活性维持在恒定水平。放线菌酮治疗后细胞内Na+水平降低；因此，泵刺激不是由于底物效应造成的。此外，放线菌酮对 Rb+ 吸收的影响可能与对紧密连接的影响无关。这些观察结果表明 (Na+, K+) ATP 酶的转运活性受到依赖于蛋白质合成的因素的严格调节。
MDCK kidney epithelial cell cultures exposed to the differentiation inducer hexamethylene bisacetamid (HMBA) for 24 hours exhibited a 50% decrease in transport activity per (Na+, K+)‐ATPase molecule (turnover number) but an unchanged number of pump sites (Kennedy and Lever, 1984). Inhibition of protein synthesis by either 10 μM cycloheximide or 2 μM emetine blocked the inhibitory effects of HMBA on Na+/K+pump efficiency assessed by measurements of [3H]‐ouabain binding to intact cells, (Na+, K+) ATPase activity of detergent‐activated cell extracts, and ouabain‐sensitive Rb+uptake. In the absence of inducer treatment, inhibition of protein synthesis increased Na+/K+pump turnover number by twofold while maintaining Na+/K+pump activity per cell at a constant level. Intracellular Na+levels were decreased after cycloheximide treatment; therefore, pump stimulation was not due to substrate effects. Furthermore, cycloheximide effects of Rb+uptake could be dissociated from effects on tight junctions. These observations suggest that the transport activity of the (Na+, K+) ATPase is tightly regulated by factors dependent on protein synthesis.