Legionella effectors SidC/SdcA ubiquitinate multiple small GTPases and SNARE proteins to promote phagosomal maturation.

Protein ubiquitination is one of the most important posttranslational modifications (PTMs) in eukaryotes and is involved in the regulation of almost all cellular signaling pathways. The intracellular bacterial pathogen Legionella pneumophila translocates at least 26 effectors to hijack host ubiquitination signaling via distinct mechanisms. Among these effectors, SidC/SdcA are novel E3 ubiquitin ligases with the adoption of a Cys-His-Asp catalytic triad. SidC/SdcA are critical for the recruitment of endoplasmic reticulum (ER)-derived vesicles to the Legionella-containing vacuole (LCV). However, the ubiquitination targets of SidC/SdcA are largely unknown, which restricts our understanding of the mechanisms used by these effectors to hijack the vesicle trafficking pathway. Here, we demonstrated that multiple Rab small GTPases and target soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE) proteins are bona fide ubiquitination substrates of SidC/SdcA. SidC/SdcA-mediated ubiquitination of syntaxin 3 and syntaxin 4 promotes their unconventional pairing with the vesicle-SNARE protein Sec22b, thereby contributing to the membrane fusion of ER-derived vesicles with the phagosome. In addition, our data reveal that ubiquitination of Rab7 by SidC/SdcA is critical for its association with the LCV membrane. Rab7 ubiquitination could impair its binding with the downstream effector Rab-interacting lysosomal protein (RILP), which partially explains why LCVs avoid fusion with lysosomes despite the acquisition of Rab7. Taken together, our study reveals the biological mechanisms employed by SidC/SdcA to promote the maturation of the LCVs.

[Mechanism of n-butanol extract of Pulsatilla Decoction in treating ulcerative colitis by activating BMP signaling pathway].

The study aimed to investigate the therapeutic effects of the n-butanol extract of Pulsatilla Decoction(BEPD) on ulcerative colitis(UC) via the bone morphogenetic protein(BMP) signaling pathway. C57BL/6 mice were divided into six groups: control, model, mesalazine, and BEPD low-, medium-, and high-dose groups. Except for the control group, the rest groups were treated with 3% dextran sulfate sodium(DSS) freely for seven consecutive days to establish the UC mouse model, followed by treatment with different concentrations of BEPD and mesalazine by gavage. The murine body weight and disease activity index(DAI) were recorded. After the mice were sacrificed, their colon tissues were collected for histological analysis. Alcian blue/periodic acid-Schiff(AB/PAS) staining was used to detect the number and mucus secretion status of goblet cells; immunohistochemistry was performed to measure the expression of ki67, cleaved caspase-3, mucin 2(Muc2), and matrix metalloproteinase-9(MMP9) in colon tissues; and immunofluorescence was used to analyze the expression of tight junction proteins in colon tissues, and enzyme linked immunosorbent assay(ELISA) was employed to quantify the levels of tumor necrosis factor-α(TNF-α), interleukin(IL)-1ß, and IL-6. Western blot was conducted to evaluate the expression of BMP pathway-related proteins in mouse colon tissues. Quantitative real-time PCR(qRT-PCR) was performed to measure the expression of genes related to goblet cell differentiation in mouse colon tissues. In addition, this study also examined the protective effect and underlying mechanism of BEPD-containing serum on lipopolysaccharide(LPS)-induced barrier damages in LS174T goblet cells in vitro. The results showed that BEPD significantly alleviated UC symptoms in mice, restored goblet cell diffe-rentiation function, promoted Muc2 secretion and tight junction protein expression, and suppressed inflammatory factor secretion while activating the BMP signaling pathway. Therefore, BEPD may exert its therapeutic effects on UC by activating the BMP signaling pathway, providing a new strategy for drug intervention in UC.

Cinnamaldehyde Ameliorates Dextran Sulfate Sodium-Induced Colitis in Mice by Modulating TLR4/NF-κB Signaling Pathway and NLRP3 Inflammasome Activation.

Ulcerative colitis (UC) is a chronic inflammatory gastrointestinal disease mainly associated with immune dysfunction and microbiota disturbance. Cinnamaldehyde (CIN) is an active ingredient of Cinnamomum cassia with immunomodulatory and anti-inflammatory properties. However, the therapeutic effect and detailed mechanism of CIN on UC remains unclear, and warrant further dissection. In this study, network pharmacology and molecular docking analyses were introduced to predict the potential targets and mechanism of CIN against UC. The therapeutic effect and the predicted targets of CIN on UC were further validated by in vivo and in vitro experiments. Seven intersection targets shared by CIN and UC were obtained, and four hub targets, i. e., toll-like receptor 4 (TLR4), transcription factor p65 (NF-κB), NF-kappa-B inhibitor alpha (IκBα), prostaglandin G/H synthase 2 (COX2) were acquired, which were mainly involved in NF-κB, tumor necrosis factor (TNF), Toll-like receptor and NOD-like receptor signaling pathways. CIN alleviated the symptoms of dextran sulfate sodium (DSS)-induced colitis by decreasing the disease active index (DAI), restoring colon length, and relieving colonic pathology. CIN attenuated systemic inflammation by reducing serum myeloperoxidase (MPO), TNF-α, interleukin-6 (IL-6), and interleukin-1ß (IL-1ß), down-regulating TLR4, phosphorylated-NF-κB (p-NF-κB), phosphorylated-IκBα (p-IκBα), and COX2 expression in colonic tissues, and decreasing NOD-like receptor protein 3 (NLRP3), Caspase-1, and IL-1ß protein expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. These results indicate that CIN alleviates DSS-induced colitis inflammation by modulating TLR4/NF-κB signaling pathway and NLRP3 inflammasome activation.

[Mechanism of Shenling Baizhu Powder in alleviation of ulcerative colitis in mice based on high-throughput transcriptome sequencing].

High-throughput transcriptome sequencing was used to study the mechanism of Shenling Baizhu Powder(SLBZP) in the alleviation of the dextran sulfate sodium(DSS)-induced ulcerative colitis(UC) in mice. The mouse model of DDS-induced UC was treated with SLBZP by gavage. The changes in general state, disease activity index(DAI), and colon length were observed. The hematoxylin-eosin(HE) staining was used to observe the pathological changes in the colon tissues of mice. Enzyme-linked immunosorbent assay(ELISA) was used to determine the expression levels of tumor necrosis factor-α(TNF-α), interleukin(IL)-1ß, IL-6, IL-4, and IL-10 in the serum and tissues of mice. The differentially expressed genes in the control group, the model group, and the SLBZP group were analyzed by high-throughput transcriptome sequencing, and the Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analyses were conducted on the differentially expressed genes. The results showed that after intragastric administration of SLBZP, the symptoms of diarrhea and bloody stool were improved, and the disease active index(DAI) score was reduced. SLBZP effectively reduced the inflammatory cell infiltration and goblet cell loss in the colonic mucosal tissue, reduced the levels of TNF-α, IL-1ß, IL-6 in the serum and colon tissue, and increased the levels of IL-4 and IL-10 in the serum and colon tissue. There were 25 differential genes in SLBZP vs the model group, which were significantly enriched in immune response, immune system process, immunoglobulin production, and other biological processes. KEGG pathway analysis showed that the differential genes were enriched in signaling pathways such as neomycin, kanamycin, and gentamicin biosynthesis, cytokine-cytokine receptor interaction, primary immunodeficiency, and IgA synthesis of the intestinal immune network. This study shows that SLBZP may alleviate UC through immune regulation.

The bacterial deubiquitinase Ceg23 regulates the association of Lys-63-linked polyubiquitin molecules on the Legionella phagosome.

Legionella pneumophila is the causative agent of the lung malady Legionnaires' disease, it modulates host function to create a niche termed the Legionella-containing vacuole (LCV) that permits intracellular L. pneumophila replication. One important aspect of such modulation is the co-option of the host ubiquitin network with a panel of effector proteins. Here, using recombinantly expressed and purified proteins, analytic ultracentrifugation, structural analysis, and computational modeling, along with deubiquitinase (DUB), and bacterial infection assays, we found that the bacterial defective in organelle trafficking/intracellular multiplication effector Ceg23 is a member of the ovarian tumor (OTU) DUB family. We found that Ceg23 displays high specificity toward Lys-63-linked polyubiquitin chains and is localized on the LCV, where it removes ubiquitin moieties from proteins ubiquitinated by the Lys-63-chain type. Analysis of the crystal structure of a Ceg23 variant lacking two putative transmembrane domains at 2.80 Å resolution revealed that despite very limited homology to established members of the OTU family at the primary sequence level, Ceg23 harbors a catalytic motif resembling those associated with typical OTU-type DUBs. ceg23 deletion increased the association of Lys-63-linked polyubiquitin with the bacterial phagosome, indicating that Ceg23 regulates Lys-63-linked ubiquitin signaling on the LCV. In summary, our findings indicate that Ceg23 contributes to the regulation of the association of Lys-63 type polyubiquitin with the Legionella phagosome. Future identification of host substrates targeted by Ceg23 could clarify the roles of these polyubiquitin chains in the intracellular life cycle of L. pneumophila and Ceg23's role in bacterial virulence.

Abundance interaction in Candida albicans and Candida glabrata mixed biofilms under diverse conditions.

Candida albicans and Candida glabrata are frequently coisolated from the oral cavity in immunosuppressive or immunocompromised individuals. Their relationship is usually defined as competition as C. glabrata can inhibit growth of C. albicans in cohabitation. In this study, eight C. albicans isolates as well as two C. glabrata strains were used to investigate the effects of culture medium (Roswell Park Memorial Institute [RPMI]-1640, YPD, YND), incubation time (24 h, 48 h, 72 h, 96 h), initial inoculum (C. glabrata: C. albicans = 2:1, 1:1, 1:2), and medium state (static and dynamic states) on viable cell enumeration and relative abundance in both Candida SB and MB. The results showed that in most cases, C. glabrata and C. albicans SB and MB flourished in RPMI-1640 at 24 h under dynamic state compared with other conditions. Except YPD medium, there were high proportions of preponderance of C. albicans over C. glabrata in MB compared with SB. High initial inoculum promoted corresponding Candida number in both SB and MB and its abundance in MB relative to SB. This study revealed an impact of several environmental conditions on the formation of C. albicans and C. glabrata SB and MB and their abundance in MB in comparison with SB, deepening our understanding of both Candida interaction and their resistance mechanism in MB. LAY SUMMARY: This study described the effects of diverse experimental conditions on the numbers of Candida albicans and Candida glabrata single biofilms and mixed biofilms and their abundance.

Paeonol alleviates dextran sodium sulfate induced colitis involving Candida albicans-associated dysbiosis.

Inflammatory bowel disease (IBD), which consists of ulcerative colitis (UC) and Crohn's disease (CD), is a chronic inflammatory disorder of the gastrointestinal tract. Occurrence and development of UC have been associated with multiple potential causative factors, which include fungal dysbiosis. Growing evidence reveals that Candida albicans-associated dysbiosis is correlated with clinical deterioration in UC. Paeonol (PAE) is a commonly used traditional medicine with multiple reported properties including effective alleviation of UC. In this study, a murine UC model was established by colonizing mice with additional C. albicans via gavage prior to dextran sodium sulfate (DSS) administration. Effects of PAE treatment were also assessed at initiation and in preestablished C. albicans-associated colitis. The results showed that C. albicans supplementation could aggravate disease activity index (DAI), compromise mucosal integrity, exacerbate fecal and tissue fungal burdens, increase serum ß-glucan and anti-Saccharomyces cerevisiae antibody (ASCA) levels, promote serum and colonic tissue pro-inflammatory cytokine secretion (tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6, and IL-8) and decrease the anti-inflammatory cytokine IL-10 level. It also stimulated Dectin-1, TLR2 and TLR4 as well as expression of their downstream effector NF-κB in colonic tissue. After PAE treatment, the adverse impacts of C. albicans on colitis were relieved, via decreased receptor-associated local and systemic inflammation. Our study suggests that PAE should be a candidate for treatment of fungal dysbiosis-associated UC and may act through the Dectin-1/NF-κB pathway in collaboration with TLR2 and TLR4. LAY SUMMARY: Candida albicans is believed to be an important stimulator in ulcerative colitice (UC) development. Suppressing the growth of intestinal C. albicans can be contributory to the amelioration of UC. Paeonol (PAE) is a commonly used traditional medicine with multiple biological functions. In this study, we observed that PAE could alleviate symptoms in mice UC model accompanying with burden reduction of C. albicans. Therefore, we suppose that PAE can be a candidate in the treatment of C. albicans-associated UC.

[Mechanism of Sanhuang Decoction in alleviating dextran sulfate sodium induced ulcerative colitis in mice with Candida albicans colonization:based on high-throughput transcriptome sequencing].

This study explored the mechanism of Sanhuang Decoction(SHD) in treating dextran sulfate sodium(DSS)-induced ulcerative colitis(UC) in mice with Candida albicans(Ca) colonization via high-throughput transcriptome sequencing. Specifically, the animal model was established by oral administration of 3.0% DSS for 7 days followed by intragastrical administration of Ca suspension at 1.0 × 10~8 cells for 4 days and then the mice were treated with SHD enema for 7 days. Afterwards, the general signs were observed and the disease activity index(DAI) was recorded every day. After mice were sacrificed, colon length and colon mucosa damage index(CMDI) were determined and the histomorphology was observed with the HE staining method. The fungal loads of feces were detected with the plate method. Anti-saccharomyces cerevisiae antibody(ASCA) and ß-1,3-glucan in serum, and TNF-α, IL-1ß, and IL-6 in serum and colon were detected by ELISA. High-throughput RNA sequencing method was adopted to identify transcriptome of colon tissues from the control, model and SHD(15.0 g·kg~(-1)) groups. Differentially expressed genes(DEGs) among groups were screened and the GO and KEGG pathway enrichment analysis of the DEGs was performed. The expression levels of NLRP3, ASC, caspase-1, and IL-1ß genes related to the NOD-like receptor signaling pathway which involved 9 DEGs, were examined by qRT-PCR and Western blot. The results demonstrated that SHD improved the general signs, decreased DAI and Ca loads of feaces, alleviated colon edema, erosion, and shortening, and lowered the content of ß-1,3-glucan in serum and TNF-α, IL-1ß, and IL-6 in serum and colon tissues of mice. Transcriptome sequencing revealed 383 DEGs between SHD and model groups, which were mainly involved in the biological processes of immune system, response to bacterium, and innate immune response. They were mainly enriched in the NOD-like signaling pathway, cytokine-cytokine interaction pathway, and retinol metabolism pathway. Moreover, SHD down-regulated the mRNA and protein levels of NLRP3, caspase-1, and IL-1ß. In a word, SHD ameliorates DSS-induced UC in mice colonized with Ca, which probably relates to its regulation of NOD-like receptor signaling pathway.

Transcriptome analysis of Clinopodium gracile (Benth.) Matsum and identification of genes related to Triterpenoid Saponin biosynthesis.

BACKGROUND: Clinopodium gracile (Benth.) Matsum (C. gracile) is an annual herb with pharmacological properties effective in the treatment of various diseases, including hepatic carcinoma. Triterpenoid saponins are crucial bioactive compounds in C. gracile. However, the molecular understanding of the triterpenoid saponin biosynthesis pathway remains unclear. RESULTS: In this study, we performed RNA sequencing (RNA-Seq) analysis of the flowers, leaves, roots, and stems of C. gracile plants using the BGISEQ-500 platform. The assembly of transcripts from all four types of tissues generated 128,856 unigenes, of which 99,020 were mapped to several public databases for functional annotation. Differentially expressed genes (DEGs) were identified via the comparison of gene expression levels between leaves and other tissues (flowers, roots, and stems). Multiple genes encoding pivotal enzymes, such as squalene synthase (SS), or transcription factors (TFs) related to triterpenoid saponin biosynthesis were identified and further analyzed. The expression levels of unigenes encoding important enzymes were verified by quantitative real-time PCR (qRT-PCR). Different chemical constituents of triterpenoid saponins were identified by Ultra-Performance Liquid Chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS). CONCLUSIONS: Our results greatly extend the public transcriptome dataset of C. gracile and provide valuable information for the identification of candidate genes involved in the biosynthesis of triterpenoid saponins and other important secondary metabolites.

Antifungal evaluation of traditional herbal monomers and their potential for inducing cell wall remodeling in Candida albicans and Candida auris.

Traditional herbal monomers (THMs) are widely distributed in many traditional Chinese formulas (TCFs) and decoctions (TCDs) and are frequently used for the prevention and treatment of fungal infections. The antifungal activities of five common THMs, including sodium houttuyfonate (SH), berberine (BER), palmatine (PAL), jatrorrhizine (JAT) and cinnamaldehyde (CIN), and their potential for inducing cell wall remodeling (CWR), were evaluated against Candida albicans SC5314 and Candida auris 12372. SH/CIN plus BER/PAL/JAT showed synergistic antifungal activity against both Candida isolates. Furthermore, SH-associated combinations (SH plus BER/PAL/JAT) induced stronger exposure of ß-glucan and chitin than their counterparts, while CIN triggered more marked exposure compared with CIN-associated combinations (CIN plus BER/PAL/JAT). Collectively, this study demonstrated the anti-Candida effect and the CWR induction potential of the five THMs and their associated combinations, providing a possibility of their in vivo application against fungal-associated infections.

[Therapeutic effect of cinnamaldehyde on ulcerative colitis in mice induced by dextran sulfate sodium with Candida albicans colonization and its effect on dectin-1/TLRs/NF-κB signaling pathway].

To observe the efficacy of cinnamaldehyde on dextran sulfate sodium(DSS)-induced ulcerative colitis(UC) with Can-dida albicans(Ca) colonization and its effect on dectin-1/TLRs/NF-κB signaling pathway in mice. C57 BL/6 mice were randomly divided into normal group, DSS group, DSS+Ca group, cinnamaldehyde group and mesalazine group. Mice in DSS+Ca group were given Ca(1×10~8 CFU per mouse) through intragastrical administration for 4 consecutive days and then distilled water with 3.0% DSS for 7 consecutive days. In cinnamaldehyde group and mesalazine group, in addition to the induction method of the DSS+Ca group, mice were given 75 mg·kg~(-1) cinnamaldehyde and 200 mg·kg~(-1) mesalazine accompanied with 3.0% DSS for 7 consecutive days, respectively. Mice in normal group and DSS group were correspondingly administered with distilled water. The general conditions of the mice were observed daily, the diseased activity index(DAI) score was calculated, and fungal loads of feces were detected by plate method. The mice were sacrificed on day 12, colon length was measured, colon mucosa damage index(CMDI) score was calculated, and histopathological analysis was carried out by HE staining. Anti-saccharomces cerevisiae antibody(ASCA) and ß-1,3-glucan in serum, and TNF-α, IL-1ß, IL-6, IL-8, IL-10 in serum and colon tissue were detected by ELISA. The contents of ß-1,3-glucan and macrophage infiltration in colon tissues were examined by immunofluorescence staining. The protein expressions of dectin-1, TLR2, TLR4 and NF-κB were detected by Western blot and immunohistochemistry staining. The results showed that cinnamaldehyde could significantly improve the general conditions of UC mice with Ca colonization, decrease DAI and histopathological scores, reduce intestinal mucosal congestion, erosion and colon shortening, decrease Ca load in mouse feces and tissues, down-regulate the contents of ASCA and ß-1,3-glucan in serum, reduce the contents of TNF-α, IL-1ß, IL-6, IL-8 and increase IL-10 in serum and colon tissues, inhibit macrophages infiltration and down-regulate the protein expression of dectin-1, TLR2, TLR4 and NF-κB in colon tissue. These results suggested that cinnamaldehyde had a therapeutic effect on UC mice with Ca colonization, which might be related to the inhibition of Ca proliferation, the regulation of dectin-1/TLRs/NF-κB signaling pathways and the coordination of the balance between pro-inflammatory and anti-inflammatory factors.

Inhibition of the type III secretion system by syringaldehyde protects mice from Salmonella enterica serovar Typhimurium.

The invasiveness of Salmonella enterica serovar Typhimurium (S. Typhimurium) is closely associated with the Salmonella pathogenicity island (SPI)-encoded type Ⅲ secretion system (T3SS), which can directly inject a series of effector proteins into eukaryotic cells to enable bacterial infection. In this study, syringaldehyde was identified as an effective inhibitor of the S. Typhimurium T3SS using an effector protein-lactamase fusion reporter system. Syringaldehyde treatment could inhibit the expression of important effector proteins (SipA, SipB and SipC) at a concentration of 0.18 mM without affecting bacterial growth. Additionally, significant inhibition of bacterial invasion and cellular injury was observed following the syringaldehyde treatment in the co-infection system of HeLa cells and S. Typhimurium. Furthermore, treatment with syringaldehyde provided systemic protection to mice infected with S. Typhimurium, reducing mortality (40.00%) and bacterial loads and relieving caecal damage and systemic inflammation. The results presented in this study indicate that syringaldehyde significantly affects T3SS activity and is a potential leading compound for treating S. Typhimurium infections.

Transcriptome Analysis of Clinopodium chinense (Benth.) O. Kuntze and Identification of Genes Involved in Triterpenoid Saponin Biosynthesis.

Clinopodium chinense (Benth.) O. Kuntze (C. chinense) is an important herb in traditional Chinese medicine. Triterpenoid saponins are a major class of active compounds in C. chinense with broad pharmacological activities and hemostatic, antitumor, and anti-hyperglycemic effects. To identify genes involved in triterpenoid saponin biosynthesis, transcriptomic analyses of leaves, stems, and roots from C. chinense were performed. A total of 135,968 unigenes were obtained by assembling the leaf, stem, and root transcripts, of which 102,154 were annotated in public databases. Differentially expressed genes were determined based on expression profile analysis and analyzed for differential expression of unique genes related to triterpenoid saponin biosynthesis. Multiple unigenes encoding crucial enzymes or transcription factors involved in triterpenoid saponin synthesis were identified and analyzed. The expression levels of unigenes encoding enzymes were experimentally validated using quantitative real-time PCR. This study greatly broadens the public transcriptome database for this species and provides a valuable resource for identifying candidate genes involved in the biosynthesis of triterpenoid saponins and other secondary metabolites.

[Mechanism of butyl alcohol extract of Baitouweng Decoction (BAEB) on Candida albicans biofilms based on pH signal pathway].

This study aimed to investigate the effect of butyl alcohol extract of Baitouweng Decoction( BAEB) on Candida albicans biofilms based on pH signal pathway. The morphology of biofilms of the pH mutants was observed by scanning electron microscope. The biofilm thickness of the pH mutants was measured by CLSM. The biofilm activity of the pH mutants was analyzed by microplate reader.The biofilm damage of the pH mutants was detected by flow cytometry. The expression of pH mutant biofilm-related genes was detected by qRT-PCR. The results showed that the deletion of PHR1 gene resulted in the defect of biofilm,but there were more substrates for PHR1 complementation. BAEB had no significant effect on the two strains. RIM101 gene deletion or complementation did not cause significant structural damage,but after BAEB treatment,the biofilms of both strains were significantly inhibited. For the biofilm thickness,PHR1 deletion or complementation caused the thickness to decrease,after BAEB treatment,the thickness of the two strains did not change significantly. However,RIM101 gene deletion or complementation had little effect on the thickness,and the thickness of the two strains became thinner after adding BAEB. For biofilm activity,PHR1 deletion or complementation and RIM101 deletion resulted in decreased activity,RIM101 complementation did not change significantly; BAEB significantly inhibited biofilm activity of PHR1 deletion,PHR1 complemetation,RIM101 deletion and RIM101 complemetation strains. For the biofilm damage,PHR1 gene deletion or complementation,RIM101 gene deletion or complementation all showed different degrees of damage; after adding BAEB,the damage rate of PHR1 deletion or complementation was not significantly different,but the damage rate of RIM101 deletion or complementation was significantly increased. Except to the up-regulation of HSP90 gene expression,ALS3,SUN41,HWP1,UME6 and PGA10 genes of PHR1 deletion,PHR1 complementation,RIM101 deletion,and RIM101 complementation strains showed a downward expression trend. In a word,this study showed that mutations in PHR1 and RIM101 genes in the pH signaling pathway could enhance the sensitivity of the strains to the antifungal drug BAEB,thus inhibiting the biofilm formation and related genes expression in C. albicans.

[Cloning and characterization of chalcone synthase and chalcone isomerase genes in Arisaema heterophyllum].

Chalcone synthase( CHS) and chalcone isomerase( CHI) are key enzymes in the biosynthesis pathway of flavonoids. In this study,unigenes for CHS and CHI were screened from the transcriptome database of Arisaema heterophyllum. The open reading frame( ORFs) of chalcone synthase( Ah CHS) and chalcone isomerase( Ah CHI) were cloned from the plant by RT-PCR. The physicochemical properties,expression and structure characteristics of the encoded proteins Ah CHS and Ah CHI were analyzed. The ORFs of Ah CHS and Ah CHI were 1 176,630 bp in length and encoded 392,209 amino acids,respectively. Ah CHS functioned as a symmetric homodimer. The N-terminal helix of one monomer entwined with the corresponding helix of another monomer. Each CHS monomer consisted of two structural domains. In particular,four conserved residues define the active site. The tertiary structure of Ah CHI revealed a novel open-faced ß-sandwich fold. A large ß-sheet( ß4-ß11) and a layer of α-helices( α1-α7) comprised the core structure. The residues spanning ß4,ß5,α4,and α6 in the three-dimensional structure were conserved among CHIs from different species. Notably,these structural elements formed the active site on the protein surface,and the topology of the active-site cleft defined the stereochemistry of the cyclization reaction. The homology comparison showed that Ah CHS had the highest similarity to the CHS of Anthurium andraeanum,while Ah CHI had the highest similarity to the CHI of Paeonia delavayi. This study provided the basis for the functional study of Ah CHS and Ah CHI and the further study on plant flavonoid biosynthesis pathway.

Upregulation of Ubiquitin Carboxyl-Terminal Hydrolase L1 (UCHL1) Mediates the Reversal Effect of Verapamil on Chemo-Resistance to Adriamycin of Hepatocellular Carcinoma.

BACKGROUND The aim of this study was to investigate the role of ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) in the reversal effect of verapamil (VER) on chemo-resistance to Adriamycin (ADM) in treatment of hepatocellular carcinoma (HCC). MATERIAL AND METHODS HCC cell lines SMMC-7721 and BEL-7402 were used as model cell lines. High-throughput transcriptome sequencing based on Illumina technology was used to screen whether UCHL1 mediated the reversal effect of VER on chemo-resistance. Quantitative real-time PCR (qRT-PCR) was performed to determine the expression level of UCHL1 mRNA in HCC cells, and western blot analysis was performed to examine the protein expression of UCHL1 protein in HCC cells. Immunohistochemistry assay was performed to determine the protein expression of UCHL1 in tissue samples from patients presenting with either positive or negative responses to the reversal therapeutic regimen of VER. Moreover, cell models with UCHL1 knockdown and overexpression were established to examine the reversal effect of VER on chemo-resistance to ADM in HCC cells. Cell apoptosis was determined by flow cytometry following Annexin V-PI staining. RESULTS The expression levels of UCHL1 genes correlated with the level of apoptosis induced by ADM+VER. Overexpression of UCHL1 genes promoted apoptosis in cells treated with VER+ADM. UCHL1 knockdown using siRNA weakened the effect of ADM+VER, indicating that ADM+VER promotes HCC cell apoptosis and that UCHL1 genes participate in VER-mediated promotion in tumor cell apoptosis. CONCLUSIONS Upregulation of UCHL1 enhanced the reversal effect of VER on chemo-resistance to ADM and promoted cell apoptosis. The underlying mechanism of the function of UCHL1 and the signaling pathway involved in its effect are to be investigated in our future research.

Loss of miR-638 in vitro promotes cell invasion and a mesenchymal-like transition by influencing SOX2 expression in colorectal carcinoma cells.

BACKGROUND: Colorectal carcinoma (CRC) is a major cause of cancer mortality. The aberrant expression of several microRNAs is associated with CRC progression; however, the molecular mechanisms underlying this phenomenon are unclear. METHODS: miR-638 and SRY-box 2 (SOX2) expression levels were detected in 36 tumor samples and their adjacent, non-tumor tissues from patients with CRC, as well as in 4 CRC cell lines, using real-time quantitative RT-PCR (qRT-PCR). SOX2 expression levels were detected in 90 tumor samples and their adjacent tissue using immunohistochemistry. Luciferase reporter and Western blot assays were used to validate SOX2 as a target gene of miR-638. The regulation of SOX2 expression by miR-638 was assessed using qRT-PCR and Western blot assays, and the effects of exogenous miR-638 and SOX2 on cell invasion and migration were evaluated in vitro using the HCT-116 and SW1116 CRC cell lines. RESULTS: We found that miR-638 expression was differentially impaired in CRC specimens and dependent on tumor grade. The inhibition of miR-638 by an antagomiR promoted cell invasion and a mesenchymal-like transition (lamellipodium stretching increased and cell-cell contacts decreased, which was accompanied by the suppression of the epithelial cell marker ZO-1/E-cadherin and the upregulation of the mesenchymal cell marker vimentin). A reporter assay revealed that miR-638 repressed the luciferase activity of a reporter gene coupled to the 3'-untranslated region of SOX2. miR-638 overexpression downregulated SOX2 expression, and miR-638 inhibition upregulated SOX2 expression. Moreover, miR-638 expression levels were correlated inversely with SOX2 mRNA levels in human CRC tissues. The RNAi-mediated knockdown of SOX2 phenocopied the invasion-inhibiting effect of miR-638; furthermore, SOX2 overexpression blocked the miR-638-induced CRC cell transition to epithelial-like cells. CONCLUSIONS: These results demonstrate that the loss of miR-638 promotes invasion and a mesenchymal-like transition by directly targeting SOX2 in vitro. These findings define miR-638 as a new, invasion-associated tumor suppressor of CRC.

Bacterial ubiquitin ligases hijack the host deubiquitinase OTUB1 to inhibit MTORC1 signaling and promote autophagy.

Many bacterial pathogens have evolved effective strategies to interfere with the ubiquitination network to evade clearance by the innate immune system. Here, we report that OTUB1, one of the most abundant deubiquitinases (DUBs) in mammalian cells, is subjected to both canonical and noncanonical ubiquitination during Legionella pneumophila infection. The effectors SidC and SdcA catalyze OTUB1 ubiquitination at multiple lysine residues, resulting in its association with a Legionella-containing vacuole. Lysine ubiquitination by SidC and SdcA promotes interactions between OTUB1 and DEPTOR, an inhibitor of the MTORC1 pathway, thus suppressing MTORC1 signaling. The inhibition of MTORC1 leads to suppression of host protein synthesis and promotion of host macroautophagy/autophagy during L. pneumophila infection. In addition, members of the SidE family effectors (SidEs) induce phosphoribosyl (PR)-linked ubiquitination of OTUB1 at Ser16 and Ser18 and block its DUB activity. The levels of the lysine and serine ubiquitination of OTUB1 are further regulated by effectors that function to antagonize the activities of SidC, SdcA and SidEs, including Lem27, DupA, DupB, SidJ and SdjA. Our study reveals an effectors-mediated complicated mechanism in regulating the activity of a host DUB.Abbreviations: BafA1: bafilomycin A1; BMDMs: bone marrow-derived macrophages; DUB: deubiquitinase; Dot/Icm: defective for organelle trafficking/intracellular multiplication; DEPTOR: DEP domain containing MTOR interacting protein; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; L. pneumophila: Legionella pneumophila; LCV: Legionella-containing vacuole; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MOI: multiplicity of infection; MTORC1: mechanistic target of rapamycin kinase complex 1; OTUB1: OTU deubiquitinase, ubiquitin aldehyde binding 1; PR-Ub: phosphoribosyl (PR)-linked ubiquitin; PTM: posttranslational modification; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SidEs: SidE family effectors; Ub: ubiquitin.

DNA methylation-regulated miR-193a-3p dictates resistance of hepatocellular carcinoma to 5-fluorouracil via repression of SRSF2 expression.

Chemoresistance prevents effective cancer therapy and is rarely predictable prior to treatment, particularly for hepatocellular carcinoma (HCC). Following the chemoresistance profiling of eight HCC cell lines to each of nine chemotherapeutics, two cell lines (QGY-7703 as a sensitive and SMMC-7721 as a resistant cell line to 5-fluorouracil (5-FU) treatment) were systematically studied for mechanistic insights underpinning HCC 5-FU chemoresistance. Genomic profiling at both DNA methylation and microRNA (miR) levels and subsequent mechanistic studies illustrate a new mechanism for how DNA methylation-regulated miR-193a-3p dictates the 5-FU resistance of HCC cells via repression of serine/arginine-rich splicing factor 2 (SRSF2) expression. In turn, SRSF2 preferentially up-regulates the proapoptotic splicing form of caspase 2 (CASP2L) and sensitizes HCC cells to 5-FU. Forced changes of miR-193a-3p level reverse all of the phenotypic features examined, including cell proliferation, cell cycle progression, and 5-FU sensitivity, in cell culture and in nude mice. Importantly, the siRNA-mediated repression of SRSF2 phenocopies all of the miR-193a-3p mimic-triggered changes in QGY-7703. This newly identified miR-193a-3p-SRSF2 axis highlights a new set of companion diagnostics required for optimal 5-FU therapy of HCC, which involve assaying both the DNA methylation state of the miR-193a gene and the expression of miR-193a-3p and SRSF2 and the relative level of the proapoptotic versus antiapoptotic splicing forms of caspase 2 in clinical samples.

MicroRNA 34c gene down-regulation via DNA methylation promotes self-renewal and epithelial-mesenchymal transition in breast tumor-initiating cells.

Tumor-initiating cells (T-ICs), a subpopulation of cancer cells with stem cell-like properties, are related to tumor relapse and metastasis. Our previous studies identified a distinct profile of microRNA (miRNA) expression in breast T-ICs (BT-ICs), and the dysregulated miRNAs contribute to the self-renewal and tumorigenesis of these cells. However, the underlying mechanisms for miRNA dysregulation in BT-ICs remain obscure. In the present study, we demonstrated that the expression and function of miR-34c were reduced in the BT-ICs of MCF-7 and SK-3rd cells, a breast cancer cell line enriched for BT-ICs. Ectopic expression of miR-34c reduced the self-renewal of BT-ICs, inhibited epithelial-mesenchymal transition, and suppressed migration of the tumor cells via silencing target gene Notch4. Furthermore, we identified a single hypermethylated CpG site in the promoter region of miR-34c gene that contributed to transcriptional repression of miR-34c in BT-ICs by reducing DNA binding activities of Sp1. Therefore, miR-34c reduction in BT-ICs induced by a single hypermethylated CpG site in the promoter region promotes self-renewal and epithelial-mesenchymal transition of BT-ICs.