Induction of apoptosis and ganoderic acid biosynthesis by cAMP signaling in Ganoderma lucidum

• DOI: 10.1038/s41598-017-00281-x
• Publication Date: 2017-03-16T17:15:15Z
• Authors: Bang-Jau You; Ni Tien; Miin-Huey Lee; Bo-Ying Bao; Yih-Shyuan Wu; Tsung-Chi Hu; Hong-Zin Lee
• Keywords: 0303 health sciences; Reishi; Phosphodiesterase Inhibitors; Science; Q; R; Apoptosis; Article; Triterpenes; Biosynthetic Pathways; Mitochondria; 3. Good health; 03 medical and health sciences; Farnesyl-Diphosphate Farnesyltransferase; 1-Methyl-3-isobutylxanthine; Caffeine; Gene Expression Regulation, Fungal; Cyclic AMP; Medicine; Sodium Fluoride; Intramolecular Transferases; Signal Transduction

AbstractApoptosis is an essential physiological process that controls many important biological functions. However, apoptosis signaling in relation to secondary metabolite biosynthesis in plants and fungi remains a mystery. The fungusGanoderma lucidumis a popular herbal medicine worldwide, but the biosynthetic regulation of its active ingredients (ganoderic acids, GAs) is poorly understood. We investigated the role of 3′,5′-cyclic adenosine monophosphate (cAMP) signaling in fungal apoptosis and GA biosynthesis inG. lucidum. Two phosphodiesterase inhibitors (caffeine and 3-isobutyl-1-methylxanthine, IBMX) and an adenylate cyclase activator (sodium fluoride, NaF) were used to increase intracellular cAMP levels. Fungal apoptosis was identified by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay and a condensed nuclear morphology. Our results showed that GA production and fungal apoptosis were induced when the mycelium was treated with NaF, caffeine, or cAMP/IBMX. Downregulation of squalene synthase and lanosterol synthase gene expression by cAMP was detected in the presence of these chemicals, which indicates that these two genes are not critical for GA induction. Transcriptome analysis indicated that mitochondria might play an important role in cAMP-induced apoptosis and GA biosynthesis. To the best of our knowledge, this is the first report to reveal that cAMP signaling induces apoptosis and secondary metabolite production in fungi.