Reprogramming of DNA methylation and changes of gene expression in grafted Hevea brasiliensis.

Rubber tree (Hevea brasiliensis) is reproduced by bud grafting for commercial planting, but significant intraclonal variations exist in bud-grafted clones. DNA methylation changes related to grafting may be partly responsible for intraclonal variations. In the current study, whole-genome DNA methylation profiles of grafted rubber tree plants (GPs) and their donor plants (DPs) were evaluated by whole-genome bisulfite sequencing. Data showed that DNA methylation was downregulated and DNA methylations in CG, CHG, and CHH sequences were reprogrammed in GPs, suggesting that grafting induced the reprogramming of DNA methylation. A total of 5,939 differentially methylated genes (DMGs) were identified by comparing fractional methylation levels between GPs and DPs. Transcriptional analysis revealed that there were 9,798 differentially expressed genes (DEGs) in the DP and GP comparison. A total of 1,698 overlapping genes between DEGs and DMGs were identified. These overlapping genes were markedly enriched in the metabolic pathway and biosynthesis of secondary metabolites by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Global DNA methylation and transcriptional analyses revealed that reprogramming of DNA methylation is correlated with gene expression in grafted rubber trees. The study provides a whole-genome methylome of rubber trees and an insight into the molecular mechanisms underlying the intraclonal variations existing in the commercial planting of grafted rubber trees.

New phenylbutenoids and terpene glycosides from Ginkgo biloba leaves.

Our continued works on the chemical constituents of Ginkgo biloba (G. biloba) leaves has led to the isolation of two novel phenylbutenoids (1, 2), along with five previously unidentified terpene glycosides (3-7). Among them, compounds 1 and 2 represent unique (Z)-phenylbutenoids, 3-6 are megastigmane glycosides, and 7 is identified as a rare bilobanone glycoside (Fig. 1). This study marks the first reported isolation of phenylbutenoid and bilobanone glycoside from G. biloba. The chemical structures of these compounds were elucidated through extensive spectroscopic analysis, including HR-ESI-MS and various 1D and 2D NMR experiments. Furthermore, the absolute configurations of these molecules were determined using Mosher's method, ECD experiments, and Cu-Kα X-ray crystallographic analyses.

Kinase inhibit region of SOCS3 attenuates IL6-induced proliferation and astrocytic differentiation of neural stem cells via cross talk between signaling pathways.

AIMS: Efficiency of neural stem cells (NSCs) therapy for brain injury is restricted by astrogliosis around the damaged region, in which JAK2/STAT3 signaling plays a key role. The SOCS3 that can directly inhibit JAK/STAT3 pathway. Here, we investigated the effects of a fusion peptide that combined kinase inhibitory region (KIR) of SOCS3 and virus trans-activator of transcription (TAT) on biological behavior of cultured NSCs under inflammatory conditions. METHODS: NSCs were isolated from embryonic brain of SD rats, TAT-KIR was synthesized, and penetration rate was evaluated by flow cytometry (FACS). CCK8, immunostaining, and FACS were used to detected of TAT-KIR on the proliferation of NSCs. The expressions of GFAP and ß tubulin III positive cells induced by IL6 with/without TAT-KIR were examined by immunostaining and Western blotting to observe the NSCs differentiation, and the effect of TAT-KIR on signaling cross talk was observed by Western blotting. RESULTS: Penetration rate of TAT-KIR into primary cultured NSCs was up to 94%. TAT-KIR did not affect the growth and viability of NSCs. It significantly reduced the NSCs proliferation that enhanced by IL-6 stimulation via blocking the cell cycle progression from the G0/G1 to S phase. In addition, TAT-KIR attenuated astrocytic differentiation and kept high level of neuronal differentiation derived from IL-6-induced NSCs. The fate of NSCs differentiation under inflammatory conditions was affected by TAT-KIR, which was associated with synchronous inhibition of STAT3 and AKT, while promoting JNK expression. CONCLUSION: TAT-KIR mimetic of SOCS3 could be a promising approach for brain repair via regulating the biological behaviors of exogenous NSCs.

Gerberdriasins A-F, six undescribed coumarin derivatives from Gerbera anandria (Linn) Sch-Bip and their protective effects on scopolamine-induced injury in PC12 cells.

A chemical investigation on the herb Gerbera anandria (Linn) Sch-Bip led to the isolation and identification of six previously undescribed coumarin derivatives, named Gerberdriasins A-F (1-6). Structurally, their chemical structures and absolute configurations were determined by nuclear magnetic resonance (1D and 2D NMR), high resolution electrospray ionization mass spectroscopy (HR-ESI-MS), experimental and quantum mechanical nuclear magnetic resonance (QM-NMR) methods, Mosher's method and calculated electronic circular dichroism (ECD) experiments. The biological activity of the obtained compounds showed that they displayed significant neuroprotective effects against scopolamine-induced injury in PC12 cells at the concentrations 12.5, 25.0 and 50.0 nM. Further study demonstrated that 1 could inhibit cell apoptosis, decrease malondialdehyde (MDA) levels and increase superoxide dismutase (SOD) activity in scopolamine-treated PC12 cells.

HbTGA1, a TGA Transcription Factor From Hevea brasiliensis, Regulates the Expression of Multiple Natural Rubber Biosynthesis Genes.

The TGA transcription factors are known to modulate the biosynthesis of secondary metabolites in plants. However, their regulatory function in natural rubber (NR) biosynthesis was not revealed in the rubber tree (Hevea brasiliensis). Here, 14 genes encoding TGA transcription factors (name HbTGA1-HbTGA14) were identified in the rubber tree. HbTGAs were differentially expressed in different tissues. HbTGA1 was expressed at its highest level in latex. We found specific in vitro and in vivo binding of the HbTGA1 protein with promoters of multiple NR biosynthesis genes (HbHMGS2, HbHMGR2, HbCPT6, HbCPT8, and HbSRPP2). The activation of the promoters of HbHMGS2 and HbCPT6 was significantly suppressed by HbTGA1, while the activities of promoters of HbHMGR2, HbCPT8, and HbSRPP2 were increased by HbTGA1. The promoter activities of HbHMGS2, HbHMGR2, HbCPT6, HbCPT8, and HbSRPP2 were significantly increased by HbTGA1 under jasmonate stress, while the promoter activities of HbHMGS2, HbHMGR2, HbCPT6, HbCPT8, and HbSRPP2 were also significantly increased by HbTGA1 under salicylic acid stress. The present study provides insights into the role of TGA transcription factors in regulating the expression of NR biosynthesis genes from H. brasiliensis.

Vlasouliodes A-D, four new C30 dimeric sesquiterpenes exhibiting potential inhibition of MCF-7 cells from Vladimiria souliei.

As our ongoing interest to search bioactive dimeric sesquiterpenes from the genus Vladimiria (Asteraceae), the plant of Vladimiria souliei was studied. Based on the repetitive chromatographic fractionation, a chemical investigation on the roots of Vladimiria souliei led to the isolation and the identification of four previously undescribed sesquiterpene dimers, vlasouliodes A-D (1-4). Their chemical structures were elucidated by comprehensive analysis of spectroscopic data, including HRESIMS, 1D and 2D NMR spectroscopic data. The absolute configurations of them were unambiguously established by the experimental and calculated ECD data. In the in vitro biological activity evaluation, 1 and 3 displayed pronounced inhibitory activity against human breast adenocarcinoma cell lines (MCF-7) with IC50 values of 17.12 ± 0.42 µM and 13.12 ± 0.10 µM, respectively. Additionally, treatment with 1 and 3 induced cell apoptosis in MCF-7 cells, down-regulated the expression of Caspase-3 and up-regulated the expression of Cleaved-caspase-3.

Coumarin-monoterpenes from Gerbera anandria (Linn.) Sch.-Bip and their neuroprotective activity.

Thirty-two undescribed coumarin-monoterpenes, including the first report of six pairs of enantiomeric and twenty congeners, were isolated from the petroleum ether extract of the stems of Gerbera anandria (Linn.) Sch.-Bip. Structurally, these compounds represented C3-substituted 5-methyl-4-hydroxycoumarin-monoterpenes. Among them, 1-7 and 10-24 were rare 5-methylcoumarin-monoterpenes formed through a furan ring. Their chemical structures and absolute configurations were determined by comprehensive analysis of spectroscopic data, including HRESIMS, 1D and 2D NMR spectroscopic data, Mosher's method, ECD calculations and single crystal X-ray diffraction. Furthermore, biological studies revealed that compounds 1-3, 3a, 5, 5a, 11-12, 21-22 and 26 had the neuroprotective effects on scopolamine-induced injury in PC12 cells. Notably, 3 exhibited the strongest neuroprotective activity with the cell viability values of 77.24%. Meanwhile, pretreatment with 3 significantly downregulate apoptosis and reactive oxygen species (ROS) production, as well as strengthen antioxidant enzyme activities (MDA and SOD). Moreover, pretreatment with 3 also could attenuate the down-regulation of HO-1 and Nrf2 induced by scopolamine. In conclusion, these results demonstrated that these compounds possessed the protective effects on scopolamine-injured PC12 cells through anti-apoptotic and anti-oxidant activities.

New ent-kaurane diterpenoid acids from Nouelia insignis Franch and their anti-inflammatory activity.

Eleven undescribed ent-kaurane-type diterpenoid acids, namely noueinsiancins A-K (1-11), together with sixteen related known analogs (12-27) were isolated from Nouelia insignis Franch. The chemical structures and absolute configurations of the new compounds were confirmed by the extensive spectroscopic data, electronic circular dichroism (ECD) data analysis and single crystal X-ray diffraction. Additionally, the anti-inflammatory assay was applied to estimate the nitric oxide (NO) inhibitory activities of all compounds by using lipopolysaccharide (LPS)-induced RAW 264.7 cells in vitro. The results revealed that 4-7 and 13-17 significantly inhibited NO production at the concentrations of 2.5 µM, 5.0 µM and 10.0 µM. Meanwhile, compounds 6 and 7 were found to down-regulate the protein expression levels of IL-6 and TNF-α in RAW 264.7 cells induced by LPS in a dose-dependent manner. In conclusion, these findings provided the reference values for exploring the new chemicals with biological activities from this genus.

Chemical approach to generating long-term self-renewing pMN progenitors from human embryonic stem cells.

Spinal cord impairment involving motor neuron degeneration and demyelination can cause lifelong disabilities, but effective clinical interventions for restoring neurological functions have yet to be developed. In early spinal cord development, neural progenitors of the motor neuron (pMN) domain, defined by the expression of oligodendrocyte transcription factor 2 (OLIG2), in the ventral spinal cord first generate motor neurons and then switch the fate to produce myelin-forming oligodendrocytes. Given their differentiation potential, pMN progenitors could be a valuable cell source for cell therapy in relevant neurological conditions such as spinal cord injury. However, fast generation and expansion of pMN progenitors in vitro while conserving their differentiation potential has so far been technically challenging. In this study, based on chemical screening, we have developed a new recipe for efficient induction of pMN progenitors from human embryonic stem cells. More importantly, these OLIG2+ pMN progenitors can be stably maintained for multiple passages without losing their ability to produce spinal motor neurons and oligodendrocytes rapidly. Our results suggest that these self-renewing pMN progenitors could potentially be useful as a renewable source of cell transplants for spinal cord injury and demyelinating disorders.

Neutralization of Hv1/HVCN1 With Antibody Enhances Microglia/Macrophages Myelin Clearance by Promoting Their Migration in the Brain.

Microglia dynamically monitor the microenvironment of the central nervous system (CNS) by constantly extending and retracting their processes in physiological conditions, and microglia/macrophages rapidly migrate into lesion sites in response to injuries or diseases in the CNS. Consequently, their migration ability is fundamentally important for their proper functioning. However, the mechanisms underlying their migration have not been fully understood. We wonder whether the voltage-gated proton channel HVCN1 in microglia/macrophages in the brain plays a role in their migration. We show in this study that in physiological conditions, microglia and bone marrow derived macrophage (BMDM) express HVCN1 with the highest level among glial cells, and upregulation of HVCN1 in microglia/macrophages is presented in multiple injuries and diseases of the CNS, reflecting the overactivation of HVCN1. In parallel, myelin debris accumulation occurs in both the focal lesion and the site where neurodegeneration takes place. Importantly, both genetic deletion of the HVCN1 gene in cells in vitro and neutralization of HVCN1 with antibody in the brain in vivo promotes migration of microglia/macrophages. Furthermore, neutralization of HVCN1 with antibody in the brain in vivo promotes myelin debris clearance by microglia/macrophages. This study uncovers a new role of HVCN1 in microglia/macrophages, coupling the proton channel HVCN1 to the migration of microglia/macrophages for the first time.

Genome-wide identification and expression analysis of terpene synthase gene family in Aquilaria sinensis.

Agarwood is the resinous portion of Aquilaria trees, and has been widely used as medicine and incense. Sesquiterpenes are the main chemical characteristic constituents of agarwood. Terpene synthase (TPS) is a critical enzyme responsible for biosynthesis of sesquiterpene compounds. However, limited information is available on genome-wide identification and characterization of the TPS family in Aquilaria trees. In this study, TPS gene family was identified and characterized in Aquilaria sinensis by bioinformatics methods. The expression of those genes was analyzed by RNA-seq and quantitative real-time PCR. Transcription factors regulating TPS gene expression were identified by yeast one-hybrid and dual-luciferase assay. In total, 26 AsTPS genes (AsTPS1-AsTPS26) were identified, which were classified into five subgroups. Many putative cis-elements putatively involved in stresses and phytohormones (especially jasmonic acid) were identified in the promoter regions of AsTPSs, suggesting that AsTPSs genes may be regulated by stresses and jasmonic acid. Expression analysis revealed seven TPS genes encoding sesquiterpene synthetases were induced by wounding and methyl jasmonic acid (MeJA), which may be related to sesquiterpene biosynthesis. By yeast one-hybrid screening, a ERF transcription factor AsERF1 was identified to interact with the AsTPS1 promoter. Subcellular localization analysis indicated AsERF1 was a nucleus-localized protein. Transient transfection of AsERF1 in leaves of Nicotiana benthamiana significantly enhanced the promoter activation of AsTPS1, suggesting AsERF1 may participate in sesquiterpene biosynthesis by regulating AsTPS1 expression. These data generated in this study provide a foundation for future studies on functional roles and regulation mechanisms of AsTPS in sesquiterpene biosynthesis and agarwood formation.

Discovery of naturally occurring inhibitors against SARS-CoV-2 3CLpro from Ginkgo biloba leaves via large-scale screening.

3-Chymotrypsin-like protease (3CLpro) is a virally encoded main proteinase that is pivotal for the viral replication across a broad spectrum of coronaviruses. This study aims to discover the naturally occurring SARS-CoV-2 3CLpro inhibitors from herbal constituents, as well as to investigate the inhibitory mechanism of the newly identified efficacious SARS-CoV-2 3CLpro inhibitors. Following screening of the inhibitory potentials of eighty herbal products against SARS-CoV-2 3CLpro, Ginkgo biloba leaves extract (GBLE) was found with the most potent SARS-CoV-2 3CLpro inhibition activity (IC50 = 6.68 µg/mL). Inhibition assays demonstrated that the ginkgolic acids (GAs) and the bioflavones isolated from GBLE displayed relatively strong SARS-CoV-2 3CLpro inhibition activities (IC50 < 10 µM). Among all tested constituents, GA C15:0, GA C17:1 and sciadopitysin displayed potent 3CLpro inhibition activities, with IC50 values of less than 2 µM. Further inhibition kinetic studies and docking simulations clearly demonstrated that two GAs and sciadopitysin strongly inhibit SARS-CoV-2 3CLprovia a reversible and mixed inhibition manner. Collectively, this study found that both GBLE and the major constituents in this herbal product exhibit strong SARS-CoV-2 3CLpro inhibition activities, which offer several promising leading compounds for developing novel anti-COVID-19 medications via targeting on 3CLpro.

Transcriptomes analysis reveals novel insight into the molecular mechanisms of somatic embryogenesis in Hevea brasiliensis.

BACKGROUND: Somatic embryogenesis (SE) is a promising technology for plant vegetative propagation, which has an important role in tree breeding. Though rubber tree (Hevea brasiliensis Muell. Arg.) SE has been founded, few late SE-related genes have been identified and the molecular regulation mechanisms of late SE are still not well understood. RESULTS: In this study, the transcriptomes of embryogenic callus (EC), primary embryo (PE), cotyledonary embryo (CE), abnormal embryo (AE), mature cotyledonary embryo (MCE) and withered abnormal embryo (WAE) were analyzed. A total of 887,852,416 clean reads were generated, 85.92% of them were mapped to the rubber tree genome. The de novo assembly generated 36,937 unigenes. The differentially expressed genes (DEGs) were identified in the pairwise comparisons of CE vs. AE and MCE vs. WAE, respectively. The specific common DEGs were mainly involved in the phytohormones signaling pathway, biosynthesis of phenylpropanoid and starch and sucrose metabolism. Among them, hormone signal transduction related genes were significantly enriched, especially the auxin signaling factors (AUX-like1, GH3.1, SAUR32-like, IAA9-like, IAA14-like, IAA27-like, IAA28-like and ARF5-like). The transcription factors including WRKY40, WRKY70, MYBS3-like, MYB1R1-like, AIL6 and bHLH93-like were characterized as molecular markers for rubber tree late SE. CML13, CML36, CAM-7, SERK1 and LEAD-29-like were also related to rubber tree late SE. In addition, histone modification had crucial roles during rubber tree late SE. CONCLUSIONS: This study provides important information to elucidate the molecular regulation during rubber tree late SE.

Tobacco rattle virus-induced gene silencing in Hevea brasiliensis.

Virus-induced gene silencing (VIGS) is a powerful gene-silencing tool that has been intensively applied in plants. To data, the application of VIGS in rubber tree has not yet been reported. In this study, we described the efficient gene silencing in rubber tree by VIGS. The gene encoding Hevea brasiliensis phytoene desaturase (HbPDS) was identified in rubber tree genome. Small interfering RNAs from HbPDS and the silencing gene fragment were predicted and a length of 399 bp was selected to be tested. We showed that the tobacco rattle virus (TRV)-VIGS could induce effective HbPDS silencing in rubber tree. This study was the first to report VIGS in rubber tree. The present TRV-VIGS method could be used to perform reverse genetic approaches to identify unknown gene functions and might be further applied to produce gene silenced rubber tree plants, to advance functional gene of rubber tree.

3,4-Secocycloartane Triterpenoids from the Cones of Pseudolarix amabilis.

Four new 3,4-secocycloartane triterpenoids, pseudolactones A-D (1-4), were isolated from the ethanol extract of the cones of Pseudol arixamabilis. Their structures were established by extensive 1D- and 2D-NMR experiments. The cones of P. arixamabilis are enriched in the ring-expanded or cleaved cycloartane triterpenoids. This work provides new insight into cycloartane triterpenoids from the cones of P. arixamabilis.

Differential Expression of lncRNAs and miRNAs Between Self-Rooting Juvenile and Donor Clones Unveils Novel Insight Into the Molecular Regulation of Rubber Biosynthesis in Hevea brasiliensis.

The rubber tree (Hevea brasiliensis Muell. Arg.) is a tropical tree species that produce natural rubber. Self-rooted juvenile clones (SRJCs) are novel rubber tree planting materials developed through primary somatic embryogenesis. SRJCs have a higher rubber yield compared with donor clones (DCs). The molecular basis underlying increased rubber yield in SRJCs remains largely unknown. Here, the latex from SRJCs and DCs were collected for strand-specific and small RNA-seq methods. A total of 196 differentially expressed long noncoding RNAs (DELs), and 11 differentially expressed microRNAs were identified in latex between SRJCs and DCs. Targeted genes of DELs were markedly enriched for various biological pathways related to plant hormone signal transduction, photosynthesis, glutathione metabolism, and amino acids biosynthesis. DELs probably acted as cis-acting regulation was calculated, and these DELs relevant to potentially regulate rubber biosynthesis, reactive oxygen species metabolism, and epigenetic modification. Furthermore, the DELs acting as microRNA targets were studied. The interaction of microRNA and DELs might involve in the regulation of natural rubber biosynthesis.

Vlasoulides A and B, a pair of neuroprotective C32 dimeric sesquiterpenes with a hexacyclic 5/7/5/5/(5)/7 carbon skeleton from the roots of Vladimiria souliei.

Vlasoulides A and B (1 and 2), a pair of epimeric C32 sesquiterpene lactone dimers, featuring a 5/7/5/5/(5)/7 ring system were isolated from the roots of Vladimiria souliei. Their chemical structures were determined by comprehensive analysis of spectroscopic data, including HRESIMS and 1D and 2D NMR spectroscopic data. Their absolute configurations were established by Mosher's method and ECD experiments. Furthermore, biological studies showed that compound 1 showed prominent neuroprotective effects against glutamate-induced neurotoxicity in PC-12 cells, with EC50 values of 13.54 ± 0.33 µM, while, the EC50 value of compound 2 is greater than 30 µM.

HbWRKY27, a group IIe WRKY transcription factor, positively regulates HbFPS1 expression in Hevea brasiliensis.

Farnesyl pyrophosphate synthase (FPS) is a key enzyme that catalyzes the formation of farnesyl pyrophosphate, the main initiator for rubber chain initiation in Hevea brasiliensis Muell. Arg. The transcriptional regulatory mechanisms of the FPS gene still not well understood. Here, a WRKY transcription factor designated HbWRKY27 was obtained by screening the latex cDNA library applied the HbFPS1 promoter as bait. HbWRKY27 interacted with the HbFPS1 promoter was further identified by individual Y1H and EMSA assays. HbWRKY27 belongs to group IIe WRKY subfamily which contains a typical WRKY domain and C-X5-CX23-HXH motif. HbWRKY27 was localized to the nucleus. HbWRKY27 predominantly accumulated in latex. HbWRKY27 was up-regulated in latex by ethrel, salicylic acid, abscisic acid, and methyl jasmonate treatment. Transient expression of HbWRKY27 led to increasing the activity of the HbFPS1 promoter in tobacco plant, suggesting that HbWRKY27 positively regulates the HbFPS1 expression. Taken together, an upstream transcription factor of the key natural rubber biosynthesis gene HbFPS1 was identified and this study will provide novel transcriptional regulatory mechanisms of the FPS gene in Hevea brasiliensis.

Five new C17/C15 sesquiterpene lactone dimers from Carpesium abrotanoides.

Five new unusual C17/C15 sesquiterpene lactone dimers, carabrodilactones A-E (1-5), along with four known common C15/C15 SLDs, carpedilactones A and B (6 and 7), faberidilactone A (8), and faberidilactone C (9), were isolated from the whole plants of Carpesium abrotanoides. The structures of 1-5 featured a flexible C-11/C-13' linked single bond between two sesquiterpene units and a tailed acetyl connected to the C-13 position. The preferential conformation of 1-5 was elucidated by the diagnostic NMR data of geminal proton of H-13. The biogenetic pathway of 1-5 was proposed to involve Stetter and Michael addition reactions. In addition, compound 1 exhibited significant cytotoxicities against the four cell lines (A549, HCT116, MDA-MB, and BEL7404 cells) with IC50 value in the range of 3.08-8.05 µM, while compounds 2-5 showed weak cytotoxicities.

Triterpenoid saponins from the roots of Psammosilene tunicoides.

Seven oleanane-type triterpenoid saponins, tunicosaponins B-D (1-3), F-I (4-7), along with eight known triterpenoid saponins (8-15), were isolated from the roots of Psammosilene tunicoides. The structures of compounds 1-7 were determined by comprehensive spectroscopic analysis, including 1D and 2D NMR techniques, mass spectrometry and chemical methods. Triterpene glycosides have been considered as major active constituents of P. tunicoides. This work provides a more complete insight into the saponin constituents of P. tunicoides.