The natural statin α,β-dehydromonacolin K exerts anti-secretory effect in human intestinal epithelial cells via a nonsense-mediated mRNA decay-dependent mechanism

cAMP-induced intestinal chloride secretion plays a pivotal role in the pathogenesis of secretory diarrheas. In this study, we investigated the antisecretory effects of α,β-dehydromonacolin K, a derivative of lovastatin from <i>Aspergillus sclerotiorum</i>, on cAMP-induced chloride secretion in human T84 cells and fluid secretion in human colonoids. Short-circuit current analyses and swelling assays were used to investigate the effects of α,β-dehydromonacolin K on chloride transport and fluid secretion, respectively. Proteomic analyses were performed to determine the potential anti-diarrheal mechanisms of α,β-dehydromonacolin K. In T84 cells, α,β-dehydromonacolin K inhibited cAMP-induced chloride secretion with an IC₅₀ of ∼ 6.32 μM. Apical chloride current analyses demonstrated that α,β-dehydromonacolin K inhibited CFTR chloride channels stimulated by cAMP agonists with an IC₅₀ of ∼ 1 μM. Basolateral potassium current analyses indicated that α,β-dehydromonacolin K had no effect on basolateral potassium channel activities. In a three-dimensional (3D) model of human colonoids, α,β-dehydromonacolin K (20 µM) suppressed both cAMP-induced and calcium-induced fluid secretion by ∼ 70%. Proteomic analyses of human colonoids revealed that α,β-dehydromonacolin K interacted with 33 proteins, including those associated with non-sense-mediated mRNA decay (NMD). Notably, the inhibitory effects of α,β-dehydromonacolin K on cAMP-induced chloride and fluid secretion were significantly diminished in the presence of SMG1i, an inhibitor of serine/threonine-protein kinase SMG1 involved in NMD, suggesting that α,β-dehydromonacolin K inhibits cAMP-induced chloride-driven fluid secretion in human intestinal epithelial cells by mechanisms involving SMG1-dependent NMD pathways. α, β-Dehydromonacolin K represents a promising class of natural compounds that exert antisecretory effects in human intestinal epithelia <i>via</i> a novel mechanism of action involving SMG1 in NMD pathways.

环腺苷酸（cAMP）诱导的肠道氯离子分泌在分泌性腹泻的发病机制中发挥关键作用。本研究针对α,β-脱氢莫纳可林K（α,β-dehydromonacolin K）的抗分泌活性展开探究——该物质是来自硬壳曲霉（<i>Aspergillus sclerotiorum</i>）的洛伐他汀衍生物，旨在明确其对人T84细胞中cAMP诱导的氯离子分泌，以及人类结肠类器官中液体分泌的调控效果。研究分别采用短路电流分析与肿胀实验，探究α,β-脱氢莫纳可林K对氯离子转运与液体分泌的作用；同时通过蛋白质组学分析，揭示该化合物潜在的抗腹泻作用机制。在人T84细胞中，α,β-脱氢莫纳可林K可抑制cAMP诱导的氯离子分泌，其半数抑制浓度（IC₅₀）约为6.32 μM。顶膜氯离子电流分析显示，α,β-脱氢莫纳可林K可抑制cAMP激动剂激活的囊性纤维化跨膜电导调节因子（CFTR）氯离子通道，半数抑制浓度约为1 μM。基底侧钾离子电流分析表明，该化合物对基底侧钾离子通道活性无显著影响。在人类结肠类器官的三维（3D）模型中，20 μM的α,β-脱氢莫纳可林K可分别抑制cAMP诱导与钙离子诱导的液体分泌，抑制率约达70%。对人类结肠类器官的蛋白质组学分析显示，α,β-脱氢莫纳可林K可与33种蛋白质结合，其中包括与无义介导的mRNA降解（NMD）相关的蛋白。值得注意的是，当加入SMG1抑制剂（SMG1i，一种参与NMD通路的丝氨酸/苏氨酸蛋白激酶SMG1的抑制剂）时，α,β-脱氢莫纳可林K对cAMP诱导的氯离子与液体分泌的抑制作用显著减弱。这表明，α,β-脱氢莫纳可林K可通过依赖SMG1的NMD通路机制，抑制人肠道上皮细胞中cAMP诱导的氯离子依赖性液体分泌。α,β-脱氢莫纳可林K是一类极具开发潜力的天然化合物，可通过涉及NMD通路中SMG1的全新作用机制，在人类肠道上皮细胞中发挥抗分泌活性。