Characterization of the Cytochrome P450 CYP716C52 in Celastrol Biosynthesis and Its Applications in Engineered Saccharomyces cerevisiae.

Celastrol is a bioactive pentacyclic triterpenoid with promising therapeutic effects that is mainly distributed in Celastraceae plants. Although some enzymes involved in the celastrol biosynthesis pathway have been reported, many biosynthetic steps remain unknown. Herein, transcriptomics and metabolic profiles of multiple species in Celastraceae were integrated to screen for cytochrome P450s (CYPs) that are closely related to celastrol biosynthesis. The CYP716 enzyme, TwCYP716C52, was found to be able to oxidize the C-2 position of polpunonic acid, a precursor of celastrol, to form the wilforic acid C. RNAi-mediated repression of TwCYP716C52 in Tripterygium wilfordii suspension cells further confirmed its involvement in celastrol biosynthesis. The C-2 catalytic mechanisms of TwCYP716C52 were further explored by using molecular docking and site-directed mutagenesis experiments. Moreover, a modular optimization strategy was used to construct an engineered yeast to produce wilforic acid C at a titer of 5.8 mg·L-1. This study elucidates the celastrol biosynthetic pathway and provides important functional genes and sufficient precursors for further enzyme discovery.

Structural and Catalytic Insight into the Unique Pentacyclic Triterpene Synthase TwOSC.

The oxidosqualene cyclase (OSC) catalyzed cyclization of the linear substrate (3S)-2,3-oxidosqualene to form diverse pentacyclic triterpenoid (PT) skeletons is one of the most complex reactions in nature. Friedelin has a unique PT skeleton involving a fascinating nine-step cation shuttle run (CSR) cascade rearrangement reaction, in which the carbocation formed at C2 moves to the other side of the skeleton, runs back to C3 to yield a friedelin cation, which is finally deprotonated. However, as crystal structure data of plant OSCs are lacking, it remains unknown why the CSR cascade reactions occur in friedelin biosynthesis, as does the exact catalytic mechanism of the CSR. In this study, we determined the first cryogenic electron microscopy structure of a plant OSC, friedelin synthase, from Tripterygium wilfordii Hook. f (TwOSC). We also performed quantum mechanics/molecular mechanics simulations to reveal the energy profile for the CSR cascade reaction and identify key residues crucial for PT skeleton formation. Furthermore, we semirationally designed two TwOSC mutants, which significantly improved the yields of friedelin and ß-amyrin, respectively.

[Cloning and functional characterization of two oxidosqualene cyclase genes from Siraitia grosvenorii].

Oxidosqualene cyclases(OSCs), belonging to a multigene family, can convert a common precursor 2,3-oxidosqualene into various types of triterpene skeletons. In this study, primers were designed according to the analysis of Siraitia grosvenorii transcriptome data, and two OSC genes SgAS1(GenBank No. QDO67189.1) and SgAS2(GenBank No. QDO67190.1) were cloned. The open reading frame(ORF) of SgAS1 was 2 262 bp, encoding 754 amino acids, and the ORF of SgAS2 was 2 289 bp, encoding 762 amino acids. Real-time quantitative PCR results demonstrated that the two SgOSCs genes showed different expression patterns in stems, leaves, and different stages of fruits. Phylogenetic analysis showed that both SgAS1 and SgAS2 were clustered with ß-amyrin synthases into a branch, but further functional characterization using yeast heterologous expression found that SgAS1 was inactive and SgAS2 could produce ß-amyrin as the sole product. Multiple sequence alignments revealed that SgAS2 had a conserved MWCYCR sequence related to ß-amyrin biosynthesis, while SgAS1 had an unusual LFCYTR sequence, for which the authors performed site-directed mutagenesis analysis of this sequence and found that tryptophan residue(W) was the key amino acid residue that affected the function of SgOSCs. In addition, the authors transformed the monofunctional ß-amyrin synthase SgAS2 into the chassis strain GH1, which was previously modified by the research group, and increased the yield of ß-amyrin to 44.05 mg·L~(-1). This study first reported the monofunctional ß-amyrin synthase SgAS2 from S. grosvenorii and conducted site-directed mutagenesis and synthetic biology investigation on it, providing a valuable resource for the directed biosynthesis of triterpenoids.

Identification of a cytochrome P450 from Tripterygium hypoglaucum (Levl.) Hutch that catalyzes polpunonic acid formation in celastrol biosynthesis.

Tripterygium hypoglaucum (Levl.) Hutch, a traditional Chinese medicinal herb with a long history of use, is widely distributed in China. One of its main active components, celastrol, has great potential to be developed into anti-cancer and anti-obesity drugs. Although it exhibits strong pharmacological activities, there is a lack of sustainable sources of celastrol and its derivatives, making it crucial to develop novel sources of these drugs through synthetic biology. The key step in the biosynthesis of celastrol is considered to be the cyclization of 2,3-oxidosqualene into friedelin under the catalysis of 2,3-oxidosqualene cyclases. Friedelin was speculated to be oxidized into celastrol by cytochrome P450 oxidases (CYP450s). Here, we reported a cytochrome P450 ThCYP712K1 from Tripterygium hypoglaucum (Levl.) Hutch that catalyzed the oxidation of friedelin into polpuonic acid when heterologously expressed in yeast. Through substrate supplementation and in vitro enzyme analysis, ThCYP712K1 was further proven to catalyze the oxidation of friedelin at the C-29 position to produce polpunonic acid, which is considered a vital step in the biosynthesis of celastrol, and will lay a foundation for further analysis of its biosynthetic pathway.

Key Glycosyltransferase Genes of Panax notoginseng: Identification and Engineering Yeast Construction of Rare Ginsenosides.

Panax notoginseng is one of the most famous valuable medical plants in China, and its broad application in clinical treatment has an inseparable relationship with the active molecules, ginsenosides. Ginsenosides are glycoside compounds that have varied structures for the diverse sugar chain. Although extensive work has been done, there are still unknown steps in the biosynthetic pathway of ginsenosides. Here, we screened candidate glycosyltransferase genes based on the previous genome and transcriptome data of P. notoginseng and cloned the full length of 27 UGT genes successfully. Among them, we found that PnUGT33 could catalyze different ginsenoside substrates to produce higher polarity rare ginsenosides by extending the sugar chain. We further analyzed the enzymatic kinetics and predicted the catalytic mechanism of PnUGT33 by simulating molecular docking. After that, we reconstructed the biosynthetic pathway of rare ginsenoside Rg3 and gypenoside LXXV in yeast. By combining the Golden Gate method and overexpressing the UDPG biosynthetic genes, we further improved the yield of engineering yeast strain. Finally, the shake-flask culture yield of Rg3 reached 51 mg/L and the fed-batch fermentation yield of gypenoside LXXV reached 94.5 mg/L, which was the first and highest record.

Emodin relieves the inflammation and pyroptosis of lipopolysaccharide-treated 1321N1 cells by regulating methyltransferase-like 3 -mediated NLR family pyrin domain containing 3 expression.

Sepsis brain injury (SBI) is a major cause of death in critically ill patients. The present study aimed to investigate the role of emodin in SBI development. Human astrocyte 1321N1 cells were stimulated with 100 ng/mL lipopolysaccharide (LPS) to establish an SBI model in vitro. Flow cytometry was performed to measure the cell pyroptosis. The protein expression levels of syndecan-1 (SDC-1), NLR family pyrin domain containing 3 (NLRP3), Caspase-1, and the N-terminal fragment of gasdermin D (GSDMD-N) were measured using Western blotting. Interleukin (IL)-1ß, IL-6, IL-10, and tumor necrosis factor (TNF)-α levels in cells were measured using enzyme-linked immunosorbent assay kits. The N6-methyladenosine (m6A) modification was analyzed using the methylated RNA immunoprecipitation assay. NLRP3 activator, nigericin, was used to overexpress NLRP3. LPS treatment significantly enhanced the pyroptosis in 1321N1 cells, increased the levels of TNF-α, IL-1ß, and IL-6, and decreased the levels of IL-10. The protein expression levels of NLRP3, SDC-1, GSDMD-N, and Caspase-1 were also increased. Emodin treatment decreased the levels of TNF-α, IL-1ß, IL-6, NLRP3, SDC-1, GSDMD-N, and Caspase-1, while increasing the levels of IL-10 in LPS-treated 1321N1 cells. Nigericin reversed the effects of emodin. Furthermore, emodin upregulated m6A levels in NLRP3 by increasing the expression of methyltransferase-like 3 (METTL3). Meanwhile, knockdown of METTL3 reversed the effects of emodin on the mRNA expression and stability of NLRP3. Therefore, emodin inhibits the inflammation and pyroptosis of LPS-treated 1321N1 cells by inactivating METTL3-mediated NLRP3 expression.

Metabolic Engineering of Saccharomyces cerevisiae for High-Level Friedelin via Genetic Manipulation.

Friedelin, the most rearranged pentacyclic triterpene, also exhibits remarkable pharmacological and anti-insect activities. In particular, celastrol with friedelin as the skeleton, which is derived from the medicinal plant Tripterygium wilfordii, is a promising drug due to its anticancer and antiobesity activities. Although a previous study achieved friedelin production using engineered Saccharomyces cerevisiae, strains capable of producing high-level friedelin have not been stably engineered. In this study, a combined strategy was employed with integration of endogenous pathway genes into the genome and knockout of inhibiting genes by CRISPR/Cas9 technology, which successfully engineered multiple strains. After introducing an efficient TwOSC1T502E, all strains with genetic integration (tHMG1, ERG1, ERG20, ERG9, POS5, or UPC2.1) showed a 3.0∼6.8-fold increase in friedelin production compared with strain BY4741. Through further double knockout of inhibiting genes, only strains GD1 and GD3 produced higher yields. Moreover, strains GQ1 and GQ3 with quadruple mutants (bts1; rox1; ypl062w; yjl064w) displayed similar increases. Finally, the dominant strain GQ1 with TwOSC1T502E was cultured in an optimized medium in shake flasks, and the final yield of friedelin reached 63.91 ± 2.45 mg/L, which was approximately 65-fold higher than that of the wild-type strain BY4741 and 229% higher than that in ordinary SD-His-Ura medium. It was the highest titer for friedelin production to date. Our work provides a good example for triterpenoid production in microbial cell factories and lays a solid foundation for the mining, pathway analysis, and efficient production of valuable triterpenoids with friedelin as the skeleton.

[Effect of isopentenyl pyrophosphate translocation on the biosynthesis of triptolide].

Triptolide has wide clinical applications due to its anti-inflammatory, anti-tumor and immunosuppressive activities. In this study, we investigated the effect of blocking isopentenyl pyrophosphate (IPP) translocation on the biosynthesis of triptolide by exogenously adding D,L-glyceraldehyde (DLG) to the suspension cells of Ttripterygium wilfordii at different stages (7 d, 14 d). Subsequently, the cell viability, biomass accumulation, triptolide contents, as well as the profiles of the key enzyme genes involved in the upstream pathway of triptolide biosynthesis, were analyzed. The results showed that IPP translocation is involved in the biosynthesis of triptolide. IPP is mainly translocated from the plastid (containing the MEP pathway) to the cytoplasm (containing the MVA pathway) in the early stage of the culture, but reversed in the late stage. Blocking the translocation of IPP affected the expression of key enzyme genes involved in the upstream pathway of triptolide, which in turn affected the accumulation of triptolide. Understanding the characteristics and mechanism of IPP translocation provides a theoretical basis for further promoting triptolide biosynthesis through synthetic biology.

[Meta analysis on the treatment of coronavirus disease 2019 by traditional Chinese and Western medicine].

OBJECTIVE: To evaluate the clinical efficacy and safety of combination of traditional Chinese and Western medicine in the treatment of coronavirus disease 2019 (COVID-19) by Meta analysis. METHODS: The clinical randomized controlled trials (RCT) and cohort studies on the treatment of COVID-19 with combination of Chinese traditional and Western medicine published on CNKI, Wanfang database, VIP database and PubMed were searched by computer from January 2020 to June 2020. Patients in the simple Western medicine treatment group were treated with routine treatment of Western medicine, and the patients in integrated traditional Chinese and Western medicine treatment group were treated with traditional Chinese medicine on the basis of routine treatment of Western medicine. The main outcome was the total effective rate of treatment. The secondary outcome were the antipyretic rate, chest CT recovery rate, lymphocyte count (LYM), C-reactive protein (CRP) level and safety. The Cochrane manual and the Newcastle Ottawa Scale (NOS) were used to evaluate the quality of the literature; the RevMan5.3 software was used to analyze the articles that meets the quality standards, and a funnel chart was drawn to evaluate the total effective publication bias. RESULTS: Thirteen articles were analyzed, including 1 039 COVID-19 patients, 559 in integrated traditional Chinese and Western medicine treatment group and 480 in simple Western medicine treatment group. The results of Meta- analysis showed that compared with the simple Western medicine treatment group, the combination of routine treatment of Western medicine and traditional Chinese medicine Qingfei Paidu decoction, Lianhua Qingwen granule, Shufeng jiedu capsule, Xuebijing injection or Reyanning mixture could significantly improve the total effective rate, antipyretic rate and chest CT recovery rate [total effective rate: odds ratio (OR) = 2.95, 95% confidence interval (95%CI) was 2.10-4.14, P < 0.000 01; antipyretic rate: OR =3.01, 95%CI was 1.64-5.53, P = 0.000 4; chest CT recovery rate: OR = 2.53, 95%CI was 1.83-3.51, P = 0.000 1], increase LYM levels [mean difference (MD) = 0.26, 95%CI was 0.02-0.50, P = 0.03], and reduce of CRP content (MD = -17.68, 95%CI was -33.14 to -2.22, P = 0.02). Based on the funnel chart analysis of 12 articles with total efficiency, the result showed that the funnel chart distribution was not completely symmetrical, indicating that there might be publication bias. CONCLUSIONS: On the basis of routine treatment with Western medicine, combined with traditional Chinese medicine can significantly improve the total effective rate of COVID-19 and improve the laboratory results and clinical symptoms of patients. Compared with the routine treatment of Western medicine alone, the combination of traditional Chinese and Western medicine has better clinical efficacy and safety.

Clinical effect of Changweishu on gastrointestinal dysfunction in patients with sepsis.

OBJECTIVE: To investigate Changweishu's clinical effect on gastrointestinal dysfunction in patients with sepsis. METHODS: Fifty patients with gastrointestinal dysfunction and sepsis were randomly divided into treatment and control groups. The control group patients received routine Western medicine treatments (meropenem, noradrenaline, glutamine glue, Bifidobacterium lactis triple-strain tablet), and the treatment group patients received routine Western medicine treatment combined with Changweishu. Treatments in both groups lasted 7 days. Changes in APACHE II score, gastrointestinal dysfunction score, serum levels of diamine oxidase (DAO), D-lactic acid, inflammatory factors (tumor necrosis factor (TNF)-α, interleukin (IL)-6, and high-mobility group box 1 (HMGB-1)), and the incidence of multiple organ dysfunction syndrome (MODS) and mortality were observed. RESULTS: After treatment, APACHE II score, gastrointestinal dysfunction score, and DAO, D-lactic acid, TNF-α, IL-6, and HMGB-1 levels decreased significantly in both groups, but the decrease was more significant in the treatment group than in the control group. The incidence of MODS and mortality were significantly lower in the treatment group than in the control group. CONCLUSION: The addition of Changweishu to routine Western treatments can improve gastrointestinal function in patients with sepsis and gastrointestinal dysfunction, as well as decreasing the incidence of MODS and mortality and improving patient prognosis.

[Visual analysis of influenza treated by traditional Chinese medicine based on CiteSpace].

OBJECTIVE: To analyze the research status, research hotspots and frontier trends of traditional Chinese medicine (TCM) in the treatment of influenza in the past 20 years through the knowledge graph, so as to provide reference basis for further research. METHODS: The related literatures of TCM in the treatment of influenza were collected in China National Knowledge Infrastructure (CNKI) from 2000 to 2019. The relevant graphs of authors, research institutions and key words were drawn by CiteSpace 5.6, the distribution and cooperation of main research forces in this field were analyzed, and the research frontiers and hot spot information in this field were discussed. RESULTS: A total of 3 048 related literatures were obtained, involving 949 authors and 242 research institutions. The analysis of the number of articles showed that the volume of articles related to the treatment of influenza with TCM fluctuated greatly in the past 20 years, which was obviously affected by the sudden hot spots around 2010, but showed an overall upward trend, with an average annual volume of about 152 articles. The analysis of the author's cooperation map showed that a total of 77 core authors had published more than 5 articles, accounting for only 8.1% of all authors, and 5 authors had published more than 30 articles. Five major teams had been formed with Gu Ligang, Liu Qingquan, Lu Fangguo, Cui Xiaolan and Zhang Fengxue as the core. The analysis of the cooperation map of research institutions showed that the cooperation among institutions was not good, and only the scientific research institutes in Beijing and Guangzhou had formed a closely related cooperation network. The keyword co-occurrence map showed that 8 keywords appeared more than 100 times, especially ultra-high-frequency keywords, influenza virus ranked first (n = 518). There were 14 key nodes, such as influenza virus, TCM treatment, viral pneumonia and so on, which supported the current research field of TCM in the treatment of influenza. Fourteen clusters were formed to classify the current research hotspots, including the nomenclature of influenza, virus type, TCM treatment, western medicine knowledge, etc., and the map showed that the clustering was reasonable and the structure was significant. Timeline graph showed that parainfluenza virus, virus disease, pharmacodynamics, heat-clearing and detoxifying drugs, bacteriostasis and experimental research had all been studied for more than 8 years, revealing the research hotspots and trends of TCM in the treatment of influenza. CONCLUSIONS: The overall research related to the treatment of influenza with TCM is relatively perfect. In the future, the close cooperation among authors and institutions should be strengthened. The molecular mechanism research, clinical and animal trials of TCM should be further studied, so as to improve the research system of TCM treatment of influenza.

Chinese Herbal Formula (CHF03) Attenuates Non-Alcoholic Fatty Liver Disease (NAFLD) Through Inhibiting Lipogenesis and Anti-Oxidation Mechanisms.

Nonalcoholic fatty liver disease (NAFLD) is a hepatic ailment with a rapidly increasing incidence in the human population due largely to dietary hyper nutrition and subsequent obesity. Discovering effective natural compounds and herbs against NAFLD can provide alternative and complementary medical treatments to current chemical pharmaceuticals. In this study, ICR male mice were fed a high-fat diet (HFD) in vivo and the AML12 cells were treated with palmitic acid (PA) in vitro. We explore the protective effect and potential mechanism of Chinese Herbal Formula (CHF03) against NAFLD by HE staining, transmission Electron Microscopy assay, Western blotting, and gene expression. In vivo, oxidative stress markers (GSH, GSH-px, MDA, SOD, and CAT) confirmed that CHF03 alleviated oxidative stress and abundance of NF-κB proteins indicating a reduction in inflammation and oxidative stress. The lower protein abundance of ACACA and FASN indicated a preventive effect on lipogenesis. Histological and ultrastructural observations revealed that CHF03 inhibited NAFLD. Expression of Srebf1, Fasn, and Acaca, which are associated with lipogenesis, were downregulated. In vitro, genes and proteins are expressed in a dose-dependent manner, consistent with those in the liver. CHF03 inhibited lipid accumulation and expression of NF-κB, nuclear transfer, and transcriptional activity in AML12 cells. The CHF03 might have a beneficial role in the prevention of hepatic steatosis by altering the expression of lipogenic genes and attenuating oxidative stress.

BMSCs laden injectable amino-diethoxypropane modified alginate-chitosan hydrogel for hyaline cartilage reconstruction.

We developed an injectable hydrogel composed of amino-diethoxypropane modified alginate and chitosan, and also investigated bone marrow mesenchy + mal stromal cells (BMSCs) laden hydrogel for cartilage reconstruction in vitro and in vivo. Different from the traditional oxidizing method, we first introduced an amino-diethoxypropane to the alginate and formed hemiacetal group on it. The hydrogel was formed when the modified alginate met with chitosan. We characterized the chemical and rheological properties of the hydrogel and investigated the growth of BMSC in hydrogel. Then, we used real-time qPCR to in vitro quantify the relative mRNA expressions of aggrecan, SOX9 and collagen II at 1, 2, 3 and 4 weeks, and found that these genes significantly presented higher expression in Group IV (BMSCs seeded in hydrogel in chondrogenic culture medium) than in BMSCs seeded in hydrogel in routine medium group (Group II) or BMSCs in chondrogenic culture medium group (Group III). For further testing, we implanted BMSCs laden hydrogel to a rabbit knee cartilage defect model. After 12 weeks, the BMSCs laden hydrogel group presented a better repair than other groups in gross appearance using ICRS histological grading system. The level of glycosaminoglycans (GAGs) was measured, and the result showed 4.9-fold higher level of glycosaminoglycans in BMSCs laden hydrogel treated group than in the defect group. The result of real-time qPCR showed that the gene expression of aggrecan (5.8-fold), type II collagen (9-fold), proteoglycans (5.3-fold), and SOX9 (17.9-fold) were significantly higher in the BMSCs loaded hydrogel treated group than in defect group, but the type I collagen gene expression was lower (4.9-fold) in BMSCs loaded hydrogel treated group than in defect group. In the histology analysis of HE, Alcian blue, Toluidine blue, and Masson's trichrome staining, the results showed that the BMSCs laden hydrogel treated group formed more chondrocytes, proteoglycans, and glycosaminoglycans (GAGs) than in the hydrogel treated group or defect group. Overall, our study showed that the developed injectable hydrogel can be loaded with BMSCs, and it can promote cartilage regeneration.

An injectable aldehyded 1-amino-3,3-diethoxy-propane hyaluronic acid-chitosan hydrogel as a carrier of adipose derived stem cells to enhance angiogenesis and promote skin regeneration.

We report an injectable aldehyded 1-amino-3,3-diethoxy-propane (ADEP)-hyaluronic acid (AHA)-chitosan (CS) hydrogel. This hydrogel can enhance wound healing by promoting cell migration, proliferation, granulation and angiogensis. During sol-gel transition, no chemical crosslinking agent was introduced and the structure of polysaccharide HA was grafted with a functional molecule, 1-amino-3,3-diethoxy-propane, but without using oxidation to break the HA structure as previously reported. Rheological tests showed the injectability and stability of this AHA-CS hydrogel. Full thickness skin defects (1 cm × 1 cm) were made on mice and the adipose derived stem cell loaded gel was tested in the healing-impaired wound. The AHA-CA hydrogel significantly accelerated wound closure, increased cell proliferation (Ki67 marker) and promoted keratinocyte migration (p63 marker). Histological examination demonstrated that the gel significantly advanced granulation tissue and capillary formation in the gel-treated wounds. mRNA expressions of angiogenesis (VEGF-A), chemotactic factors (SDF-1) and ECM-remodeling MMPs (MMP1 and MMP9) were also up-regulated in the hydrogel-treated wounds.