Molecular cloning and functional characterization of multiple ApOSCs from Andrographis paniculata

Genome-wide identification of oxidosqualene cyclase genes regulating natural rubber in Taraxacum kok-saghyz

MAIN CONCLUSION

Nine TkOSC genes have been identified by genome-wide screening. Among them, TkOSC4-6 might be more crucial for natural rubber biosynthesis in Taraxacum kok-saghyz roots. Taraxacum kok-saghyz Rodin (TKS) roots contain large amounts of natural rubber, inulin, and valuable metabolites. Oxidosqualene cyclase (OSC) is a key member for regulating natural rubber biosynthesis (NRB) via the triterpenoid biosynthesis pathway. To explore the functions of OSC on natural rubber producing in TKS, its gene family members were identified in TKS genome via genome-wide screening. Nine TkOSCs were identified, which were mainly distributed in the cytoplasm. Their family genes experienced a neutral selection during the evolution process. Overall sequence homology analysis OSC proteins revealed 80.23% similarity, indicating a highly degree of conservation. Pairwise comparisons showed a multiple sequence similarity ranging from 57% to 100%. Protein interaction prediction revealed that TkOSCs may interact with baruol synthase, sterol 1,4-demethylase, lupeol synthase and squalene epoxidase. Phylogenetic analysis showed that OSC family proteins belong to two branches. TkOSC promoter regions contain cis-acting elements related to plant growth, stress response, hormones response and light response. Protein accumulation analysis demonstrated that TkOSC4, TkOSC5 and TkOSC6 proteins had strong expression levels in the root, latex and plumular axis. Comparison of gene expression patterns showed TkOSC1, TkOSC4, TkOSC5, TkOSC6, TkOSC7, TkOSC8 and TkOSC9 might be important in regulating NRB. Combination of gene and protein results revealed TkOSC4-6 might be more crucial, and the data might contribute to a more profound understanding of the roles of OSCs for NRB in TKS roots.

Molecular Cloning and Functional Characterization of Oxidosqualene Cyclases from Panax vietnamensis

Panax vietnamensis is a valuable medicinal resource with promising preclinical applications. Ginsenosides, which are triterpenoids, are the primary active components in P. vietnamensis. Oxidosqualene cyclases (OSCs) catalyze the formation of the basic skeleton of triterpenes from 2,3-oxidosqualene, which is a crucial step in the biosynthesis of triterpenoids. The OSCs involved in triterpenoid biosynthesis in P. vietnamensis have not yet been characterized. Four OSC genes (PvOSC1-4) were cloned from P. vietnamensis and functionally characterized via heterologous expression in yeast. Transgenic yeast expressing PvOSC1, PvOSC3, and PvOSC4 produced the corresponding products β-amyrin, cycloartenol, and dammarenediol-II, respectively. PvOSC1, PvOSC3, and PvOSC4 are monofunctional OSCs. In this study, we characterized three PvOSC genes, providing a better understanding of the biosynthesis of triterpenoids in P. vietnamensis and the multiple choices of plant OSCs for metabolic engineering in yeast and other hosts.

Regulatory Effects of Andrographolide on Lung Tissue Inflammation and Th17/Treg in Rats with Chronic Obstructive Pulmonary Disease Induced by Smoking and Lipopolysaccharide

The pathogenesis of Chronic obstructive pulmonary disease (COPD) is complex, and lung tissue inflammation and Th17/Treg imbalance are the key factors causing lung dysfunction. We constructed a rat COPD model induced by smoking and lipopolysaccharide to explore andrographolide’s regulation on lung inflammation and Th17/Treg in COPD rats. By contrast, the study found that normal rats, COPD rats forced expiratory volume of 0.3 seconds (FEV0.3), FEV0.3/forced vital capacity (FVC), and peak expiratory flow (PEF) levels decreased. In addition, the levels of IL-8, TNF-α, IL-17, and IL-6 in alveolar lavage fluid increased, and the level of IL-10 decreased. Concurrently, the total number of white blood cells, monocytes and macrophages, neutrophils, and lymphocytes increased. Meanwhile, the contents of CD25, CD4, and Foxp3 in lung tissue all increased, and the protein levels of HMGB1, TLR4, and p65 increased. After treatment with andrographolide, the levels of FEV0.3, FEV0.3/FVC, and PEF increased, proving the increase was positively correlated with the concentration of andrographolide. The levels of IL-8, TNF-α, IL-17, and IL-6 in rat alveolar lavage fluid decreased, and the level of IL-10 sequentially. The total number of white blood cells, the number of monocytes and macrophages, the number of lymphocytes, and the neutral Granulocytes decreased significantly. And the contents of CD25, CD4, and Foxp3 in lung tissue significantly decreased, and the protein levels of HMGB1, TLR4, and p65 significantly decreased. The above results indicate that andrographolide might be a potential COPD treatment approach. Andrographolide improves the lung function of rats with COPD, reduces lung inflammation, regulates Th17/Treg balance, and its mechanism may be related to HMGB1/TLR4/NF-кB signaling.