Department of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, China Medical University, Taichung, Taiwan.
PLoS One. 2013;8(1):e53616. doi: 10.1371/journal.pone.0053616. Epub 2013 Jan 10.
Ganoderma lucidum is one of most widely used herbal medicine and functional food in Asia, and ganoderic acids (GAs) are its active ingredients. Regulation of GA biosynthesis and enhancing GA production are critical to using G. lucidum as a medicine. However, regulation of GA biosynthesis by various signaling remains poorly understood. This study investigated the role of apoptosis signaling on GA biosynthesis and presented a novel approach, namely apoptosis induction, to increasing GA production. Aspirin was able to induce cell apoptosis in G. lucidum, which was identified by terminal deoxynucleotidyl transferase mediated dUPT nick end labeling assay positive staining and a condensed nuclear morphology. The maximum induction of lanosta-7,9(11), 24-trien-3α-01-26-oic acid (ganoderic acid 24, GA24) production and total GA production by aspirin were 2.7-fold and 2.8-fold, respectively, after 1 day. Significantly lower levels of GA 24 and total GAs were obtained after regular fungal culture for 1.5 months. ROS accumulation and phosphorylation of Hog-1 kinase, a putative homolog of MAPK p38 in mammals, occurred after aspirin treatment indicating that both factors may be involved in GA biosynthetic regulation. However, aspirin also reduced expression of the squalene synthase and lanosterol synthase coding genes, suggesting that these genes are not critical for GA induction. To the best of our knowledge, this is the first report showing that GA biosynthesis is linked to fungal apoptosis and provides a new approach to enhancing secondary metabolite production in fungi.
灵芝是亚洲最广泛使用的草药和功能性食品之一，而灵芝酸（GAs）是其有效成分。调控 GA 生物合成和提高 GA 产量对于灵芝作为药物的应用至关重要。然而，各种信号通路对 GA 生物合成的调控仍知之甚少。本研究探讨了细胞凋亡信号对 GA 生物合成的作用，并提出了一种新的方法，即诱导细胞凋亡，以提高 GA 产量。阿司匹林能够诱导灵芝细胞凋亡，这通过末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记（TUNEL）染色阳性和核固缩形态学鉴定得到证实。阿司匹林处理后，灵芝中 lanosta-7,9(11), 24-三烯-3α-01-26-酸（灵芝酸 24，GA24）产量和总 GA 产量的最大诱导倍数分别为 2.7 倍和 2.8 倍，处理后 1 天。经过 1.5 个月的常规真菌培养，GA24 和总 GAs 的水平显著降低。阿司匹林处理后 ROS 积累和 Hog-1 激酶（哺乳动物中 MAPK p38 的假定同源物）磷酸化，表明这两个因素可能都参与了 GA 生物合成的调控。然而，阿司匹林也降低了鲨烯合酶和羊毛甾醇合酶编码基因的表达，表明这些基因对于 GA 的诱导并非关键。据我们所知，这是首次报道表明 GA 生物合成与真菌凋亡有关，并为提高真菌中次生代谢产物的产量提供了一种新方法。
