Wiesmann W P, Johnson J P, Miura G A, Chaing P K
Am J Physiol. 1985 Jan;248(1 Pt 2):F43-7. doi: 10.1152/ajprenal.1985.248.1.F43.
The effect of aldosterone (Aldo) on phospholipid (PL) biosynthesis in cultured toad bladder epithelial cells was studied in cells incubated with [1,2-14C]choline and [methyl-3H]methionine over a 5-h period. Aldo (10(-7) M) did not alter the uptake of either precursor but significantly stimulated the incorporation of both labels into phosphatidylcholine (PC), the only PL labeled. 3H labeling of PC increased 29% and 14C incorporation into PC increased 34% in cells exposed to Aldo. A similar 30% increase in protein carboxymethylation occurred in cells treated with Aldo. 3-Deazaadenosine (DZA), a methylation inhibitor, abolished the Aldo-stimulated increase in PC labeling from [3H]methionine. PC labeling from [1,2-14C]choline was not affected by DZA. Basal and Aldo-stimulated protein carboxy-methylation were inhibited by DZA. DZA (300 microM) caused a mild decrease in basal short-circuit current (ISC) but completely inhibited the ISC response to 10(-7) M Aldo. Inhibition was complete when DZA was added up to 2 h following exposure to Aldo, and was reversible. Cells previously exposed to Aldo showed a significant increase in ISC within 2 h following removal of DZA. We conclude that Aldo stimulates PL methylation, protein carboxymethylation, and turnover of PC from choline. Inhibition of methylation reactions coincides with the inhibition of ISC response to Aldo.
在以[1,2-¹⁴C]胆碱和[甲基-³H]甲硫氨酸孵育5小时的培养蟾蜍膀胱上皮细胞中，研究了醛固酮（Aldo）对磷脂（PL）生物合成的影响。醛固酮（10⁻⁷ M）不改变任何一种前体的摄取，但显著刺激两种标记物掺入磷脂酰胆碱（PC），这是唯一被标记的磷脂。在暴露于醛固酮的细胞中，PC的³H标记增加了29%，¹⁴C掺入PC增加了34%。在用醛固酮处理的细胞中，蛋白质羧甲基化也有类似的30%增加。甲基化抑制剂3-脱氮腺苷（DZA）消除了醛固酮刺激的[³H]甲硫氨酸掺入PC的增加。[1,2-¹⁴C]胆碱掺入PC不受DZA影响。基础和醛固酮刺激的蛋白质羧甲基化均被DZA抑制。DZA（300 μM）使基础短路电流（ISC）轻度降低，但完全抑制了对10⁻⁷ M醛固酮的ISC反应。当在暴露于醛固酮后2小时内加入DZA时，抑制是完全的，且是可逆的。先前暴露于醛固酮的细胞在去除DZA后2小时内ISC显著增加。我们得出结论，醛固酮刺激PL甲基化、蛋白质羧甲基化以及胆碱来源的PC周转。甲基化反应的抑制与对醛固酮的ISC反应抑制相吻合。
