Polyamines are small polycationic alkylamines involved in many fundamental cellular processes, including proliferation, nucleic acid synthesis, apoptosis, and protection from oxidative damage. It has been proposed that in addition to these functions, elevated levels of polyamines promote longevity in various biological systems, including yeast, Drosophila, and murine models. A series of in vitro mechanistic studies by multiple investigators has led to the conclusion that addition of exogenous spermidine promotes longevity through autophagy induction; however, these experiments were confounded by the use of mammalian cell culture systems supplemented with fetal bovine serum. Using cell viability assays, LC3B immunoblots, and live-cell fluorescence microscopy, we report here that in the presence of ruminant serum, exogenously added polyamines are quickly oxidized by the copper-containing bovine serum amine oxidase. This polyamine oxidation resulted in the production of harmful byproducts including hydrogen peroxide, ammonia, and reactive aldehydes. Our data demonstrate that it is critically important to prevent confounding bovine serum amine oxidase–induced cytotoxicity in mechanistic studies of the roles of polyamines in autophagy.

中文翻译：

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外源多胺诱导的自噬是培养血清中牛血清胺氧化酶活性的产物。


多胺是小的聚阳离子烷基胺，参与许多基本的细胞过程，包括增殖、核酸合成、细胞凋亡和防止氧化损伤。有人提出，除了这些功能之外，多胺水平的升高还可以促进各种生物系统的寿命，包括酵母、果蝇和小鼠模型。多名研究人员进行的一系列体外机制研究得出这样的结论：添加外源亚精胺可通过诱导自噬来延长寿命；然而，这些实验因使用补充有胎牛血清的哺乳动物细胞培养系统而受到干扰。使用细胞活力测定、LC3B 免疫印迹和活细胞荧光显微镜，我们在此报告，在反刍动物血清存在的情况下，外源添加的多胺会被含铜牛血清胺氧化酶快速氧化。这种多胺氧化导致产生有害副产物，包括过氧化氢、氨和活性醛。我们的数据表明，在多胺在自噬中的作用的机制研究中，防止混杂的牛血清胺氧化酶诱导的细胞毒性至关重要。