Biomedical subjects
Publications and source records attributed to Yin Li.
Here, we report the complete genome sequence of Tissierella sp. strain MB52-C2 (= BCRC 81439) isolated from Wuyi Mountain soil, the source region of Wuyi rock tea. The genome is 3,892,263 bp with 30.9% G + C content and supports species delineation and genomic analyses of taxonomic position and genomic features.
BACKGROUND: The association between testosterone and lung cancer remains unclear. This study investigates the relationship between testosterone levels and lung cancer risk, focusing on bioavailable testosterone levels (BTLs), total testosterone levels (TTLs), and sex hormone-binding globulin (SHBG) in relation to lung cancer subtypes. METHODS: We utilized bidirectional and multivariable Mendelian randomization (MR) analyses based on genome-wide association studies (GWAS) to assess causal links. To validate the findings clinically, immunohistochemical (IHC) staining for androgen receptor (AR) expression and survival analyses were conducted on a cohort of 90 patients with lung squamous cell carcinoma (LUSC). RESULTS: MR analysis demonstrated that higher BTLs were significantly associated with a reduced risk of LUSC (OR = 0.365, P = 0.001), while no significant associations were observed for TTLs or SHBG. Reverse MR analysis found no causal effect of lung cancer on testosterone levels. Multivariable MR confirmed BTLs as an independent protective factor. In the clinical cohort, AR expression was significantly associated with better prognosis, showing improved median progression-free survival (12.3 vs. 9.0 months, P = 0.01) and median overall survival (35.3 vs. 29.4 months, P < 0.01). Cox regression identified AR expression as an independent protective factor for patient outcomes. However, study limitations include potential residual confounding, ethnic heterogeneity between European GWAS data and Asian clinical cohorts, and the lack of direct experimental validation. CONCLUSIONS: Our findings suggest that higher BTLs may play a protective role against LUSC. BTLs and AR expression show potential as valuable biomarkers for the diagnosis and prognostic assessment of LUSC.
Terminal nucleotidyltransferase 5C (TENT5C) is a noncanonical poly(A) polymerase that promotes cancer suppression. TENT5C has been proposed to mediate the susceptibility of multiple myeloma to treatment with dexamethasone, a steroid hormone analog that binds to the glucocorticoid receptor (GR). However, the relationship between TENT5C and nuclear receptor (NR) signaling remains unclear. In this study, we investigate the regulatory role of TENT5C in the GR and estrogen receptor α (ERα) ligand complexes. We find that TENT5C acts as a corepressor of both GR and ERα. Molecular dynamics simulations indicate that the third TENT5C LXXLL motif directly interacts with ERα, but not GR. The physical interaction of TENT5C and ERα is supported by co-immunoprecipitation assays. Reporter assays show that mutations to the third TENT5C LXXLL motif disrupt TENT5C-mediated repression of ERα but do not affect the repression of the GR complex. In addition, the disruption of TENT5C poly(A) polymerase activity does not appear to affect TENT5C repression of ERα in the cell lines studied. Taken together, our findings highlight a role of TENT5C as an NR corepressor, differentially modulating GR- and ERα-induced transcriptional activity.
Intrahepatic cholangiocarcinoma (iCCA) has a poor prognosis, and elucidation of the molecular mechanisms underlying iCCA malignancy is of great significance. Glycosylation, an important post-translational modification, is closely associated with tumor progression. Altered glycosylation, including aberrant sialylation resulting from abnormal expression of sialyltransferases (STs) and neuraminidases (NEUs), is a significant feature of cancer cells. However, there is limited information on the roles of STs and NEUs in iCCA malignancy. Here, utilizing our proteogenomic resources from a cohort of 262 patients with iCCA, we identified ST3GAL1 as a prognostically relevant molecule in iCCA. Moreover, overexpression of ST3GAL1 promoted proliferation, migration, and invasion and inhibited apoptosis of iCCA cells in vitro. Through proteomic analyses, we identified the downstream pathway potentially regulated by ST3GAL1, which was the NF-κB signaling pathway, and further demonstrated that this pathway was positively correlated with malignancy in iCCA cells. Notably, glycoproteomics showed that O-glycosylation was changed in iCCA cells with high ST3GAL1 expression. Importantly, the altered O-glycopeptides underscored the potential utility of O-glycosylation profiling as a discriminatory marker for iCCA cells with ST3GAL1 overexpression. Additionally, miR-320b was identified as a post-transcriptional regulator of ST3GAL1, capable of suppressing ST3GAL1 expression and then reducing the proliferation, migration, and invasion abilities of iCCA cell lines. Taken together, these results suggest ST3GAL1 could serve as a promising therapeutic target for iCCA.
Pyruvate production by Torulopsis glabrata was used as a model to study the mechanism of product inhibition and the strategy for enhancing pyruvate production. It was found that the concentration of cell growth and pyruvate deceased with the increase of NaCl and sorbitol concentrations. To enhance the osmotic stress resistance of the strain, an NaCl-tolerant mutant RS23 was screened and selected through a pH-controlled continuous culture with 70 g/L NaCl as the selective criterion. Compared with the parent strain, mutant RS23 could grow well on the medium containing 70 g/L NaCl or 0.6 mol/L sorbitol. Pyruvate concentration by the mutant strain RS23 reached 94.3 g/L at 82 h (yield on glucose 0.635 g/g) in a 7-l fermentor with 150 g/L glucose as carbon source. Pyruvate concentration and yield of mutant RS23 were 41.1% and 11.1% higher than those of the parent strain, respectively. The strategy for enhancing pyruvate production by increasing osmotic stress resistance may provide an alternative approach to enhance organic acids production with yeast.
Two-dimensional palladium (Pd) nanostructures have been fabricated by electrochemical deposition of Pd onto an indium tin oxide glass substrate modified with a thin flat film of polypyrrole or a nanofibril film of polyaniline. The experimental results demonstrated that the morphology of Pd nanoparticles strongly depended on the properties of conducting polymers and the conditions of electrochemical deposition. Two-dimensional nanostructures composed of flower-like (consisting of staggered nanosheets) or pinecone-like Pd nanoparticles were successfully synthesized. They can be used as substrates for surface-enhanced Raman scattering after partly decomposing the polymer components by heating in air, and the enhancement factor of the substrate composed of flower-like Pd nanoparticles was measured to be as high as 105 for 4-mercaptopyridine.
An epoxide hydrolase gene of about 0.8 kb was cloned from Rhodococcus opacus ML-0004, and the open reading frame (ORF) sequence predicted a protein of 253 amino acids with a molecular mass of about 28 kDa. An expression plasmid carrying the gene under the control of the tac promotor was introduced into Escherichia coli, and the epoxide hydrolase gene was successfully expressed in the recombinant strains. Some characteristics of purified recombinant epoxide hydrolase were also studied. Epoxide hydrolase showed a high stereospecificity for L: (+)-tartaric acid, but not for D: (+)-tartaric acid. The epoxide hydrolase activity could be assayed at the pH ranging from 3.5 to 10.0, and its maximum activity was obtained between pH 7.0 and 7.5. The enzyme was sensitive to heat, decreasing slowly between 30 degrees C and 40 degrees C, and significantly at 45 degrees C. The enzyme activity was activated by Ca(2+) and Fe(2+), while strongly inhibited by Ag(+) and Hg(+), and slightly inhibited by Cu(2+), Zn(2+), Ba(2+), Ni(+), EDTA-Na(2) and fumarate.
The biological function of GFPPS1b, a novel polysaccharide-peptide isolated from cultured mycelia of Grifola frondosa GF9801, was well investigated. GFPS1b has anti-tumor activity and can significantly inhibit the proliferation of SGC-7901 cells, whereas slightly influences the growth of human normal liver cell line L-02. When treated with GFPS1b, SGC-7901 cells showed typical apoptotic morphological features such as the loss of villus and appearance of apoptotic bodies on the cell surface, volume reduction, and chromatin condensation, by scanning electron microscopy (SEM) and fluorescent microscopy (Hoechst 33342). The results of flow cytometry analysis and annexin V-PI assay showed that the SGC-7901 cell cycle was arrested in the G(2)/M phase, the subdiploid peak of DNA characteristic of apoptotic was also observed, and the apoptosis ratio was about 15.08%. DNA isolated from SGC-7901 cells cultured with GFPS1b showed a typical DNA 'ladders' of apoptosis in agarose gel electrophoresis. Further investigation results showed that the apoptotic machinery of SGC-7901 induced by GFPS1b was associated with drop in mitochondrial trans-membrane potential, upregulation of Bax, downregulation of Bcl-2, and activation of caspase-3. Our finding suggests that GFPS1b could suppress SGC-7901 cell growth and reduce cell survival via arresting cell cycle and inducing apoptosis of tumor cells.
Expression of adrenomedullin (AM), a potent vasodilator peptide, was studied during adipocyte differentiation of human mesenchymal stem cells (hMSCs). Immunoreactive AM levels in the medium were increased at day 4 and 8 of the adipocyte differentiation. Northern blot analysis showed increased expression of AM mRNA in hMSCs-derived adipocytes at day 4, 8, 12, and 18. Transient transfection assay showed that the promoter activity was higher in hMSCs-derived adipocytes than in hMSCs, when cells were transfected with plasmids containing a cis-acting region (-70/-29) of the human AM gene. Electrophoretic mobility shift assay showed that specific bands bound to the region (-70/-29) in hMSCs-derived adipocytes but not in hMSCs, and were abolished by the stimulatory protein 1 (Sp1) antibody. The present study has shown that AM expression is up-regulated during adipocyte differentiation of hMSCs probably via the interaction between Sp1 or Sp1-related factor(s) and the AM promoter region (-70/-29).
Four kinds of solvent extracts from three Chinese barley varieties (Ken-3, KA4B, and Gan-3) were used to examine the effects of extraction solvent mixtures on antioxidant activity evaluation and their extraction capacity and selectivity for free phenolic compounds in barley through free radical scavenging activity, reducing power and metal chelating activity, and individual and total phenolic contents. Results showed that extraction solvent mixtures had significant impacts on antioxidant activity estimation, as well as different extraction capacity and selectivity for free phenolic compounds in barley. The highest DPPH* and ABTS*+ scavenging activities and reducing power were found in 80% acetone extracts, whereas the strongest *OH scavenging activity, O2*- scavenging activity, and metal chelating activity were found in 80% ethanol, 80% methanol, and water extracts, respectively. Additionally, 80% acetone showed the highest extraction capacity for (+)-catechin and ferulic, caffeic, vanillic, and p-coumaric acids, 80% methanol for (-)-epicatechin and syringic acid, and water for protocatechuic and gallic acids. Furthermore, correlations analysis revealed that TPC, reducing power, DPPH* and ABTS*+ scavenging activities were well positively correlated with each other (p < 0.01). Thus, for routine screening of barley varieties with higher antioxidant activity, 80% acetone was recommended to extract free phenolic compounds from barley. DPPH* scavenging activity and ABTS*+ scavenging activity or reducing power could be used to assess barley antioxidant activity.
Manipulation of cofactor (thiamine, biotin and Ca(2+)) levels as a potential tool to redistribute carbon flux was studied in Torulopsis glabrata. With sub-optimization of vitamin in fermentation medium, the carbon flux was blocked at the key node of pyruvate, and 69 g/L pyruvate was accumulated. Increasing the concentrations of thiamine and biotin could selectively open the valve of carbon flux from pyruvate to pyruvate dehydrogenase complex, the pyruvate carboxylase (PC) pathway and the channel into the TCA cycle, leading to the over-production of alpha-ketoglutarate. In addition, the activity of PC was enhanced with Ca(2+) present in fermentation medium. By combining high concentration's vitamins and CaCO(3) as the pH buffer, a batch culture was conducted in a 7-L fermentor, with the pyruvate concentration decreased to 21.8 g/L while alpha-ketoglutarate concentration increased to 43.7 g/L. Our study indicated that the metabolic flux could be redistributed to overproduce desired metabolites with manipulating the cofactor levels. Furthermore, the manipulation of vitamin level provided an alternative tool to realize metabolic engineering goals.
This study describes how a metabolic engineering approach can be used to improve bacterial stress resistance. Some Lactococcus lactis strains are capable of taking up glutathione, and the imported glutathione protects this organism against H(2)O(2)-induced oxidative stress. L. lactis subsp. cremoris NZ9000, a model organism of this species that is widely used in the study of metabolic engineering, can neither synthesize nor take up glutathione. The study described here aimed to improve the oxidative-stress resistance of strain NZ9000 by introducing a glutathione biosynthetic capability. We show that the glutathione produced by strain NZ9000 conferred stronger resistance on the host following exposure to H(2)O(2) (150 mM) and a superoxide generator, menadione (30 microM). To explore whether glutathione can complement the existing oxidative-stress defense systems, we constructed a superoxide dismutase deficient mutant of strain NZ9000, designated as NZ4504, which is more sensitive to oxidative stress, and introduced the glutathione biosynthetic capability into this strain. Glutathione produced by strain NZ4504(pNZ3203) significantly shortens the lag phase of the host when grown aerobically, especially in the presence of menadione. In addition, cells of NZ4504(pNZ3203) capable of producing glutathione restored the resistance of the host to H(2)O(2)-induced oxidative stress, back to the wild-type level. We conclude that the resistance of L. lactis subsp. cremoris NZ9000 to oxidative stress can be increased in engineered cells with glutathione producing capability.
Production of 1,3-propanediol (1,3-PD) from glycerol by Klebsiella pneumoniae is restrained by ethanol formation. The first step in the formation of ethanol from acetyl-CoA is catalyzed by aldehyde dehydrogenase (ALDH), an enzyme that competes with 1,3-PD oxidoreductase for the cofactor NADH. This study aimed to improve the production of 1,3-PD by engineering the ethanol formation pathway. An inactivation mutation of the aldA gene encoding ALDH in K. pneumoniae YMU2 was generated by insertion of a tetracycline resistance marker. Inactivation of ALDH resulted in a nearly abolished ethanol formation but a significantly improved 1,3-PD production. Metabolic flux analysis revealed that a pronounced redistribution of intracellular metabolic flux occurred. The final titer, the productivity of 1,3-PD and the yield of 1,3-PD relative to glycerol of the mutant strain reached 927.6 mmol L(-1), 14.05 mmol L(-1)h(-1) and 0.699 mol mol(-1), respectively, which were much higher than those of the parent strain. In addition, the specific 1,3-PD-producing capability (1,3-PD produced per gram of cells) of the mutant strain was 2-fold that of the parent strain due to a lower growth yield of the mutant. By increasing NADH availability, this study demonstrates an important metabolic engineering approach to improve the efficiency of oxidoreduction-coupled bioprocesses.
Endothelin-1 (ET-1) levels in the culture medium were considered to reflect the transcription of the ET-1 gene and the subsequent secretion of ET-1 from cultured cells. It has not been clarified how different ET-1 mRNA expression levels and immunoreactive (IR)-ET levels in the culture medium are in the cell culture system. We studied ET-1 mRNA expression levels and IR-ET levels in the medium of T98G glioblastoma cells treated with cytokines. T98G glioblastoma cells were cultured with cytokines (interferon-gamma 100 U/ml, tumor necrosis factor-alpha 20 ng/ml and interleukin-1beta 10 ng/ml) under normoxia or hypoxia (1% O(2)). Northern blot analysis showed that ET-1 mRNA expression levels were increased by tumor necrosis factor-alpha alone or a combination of tumor necrosis factor-alpha and interleukin-1beta, or three cytokines, and the increase was further enhanced under hypoxia. Particularly, relative expression levels of ET-1 mRNA were significantly higher under hypoxia than in normoxia in the treatment with a combination of three cytokines. IR-ET levels in the medium were increased by treatment with tumor necrosis factor-alpha, interleukin-1beta or a combination of tumor necrosis factor-alpha and interleukin-1beta, or three cytokines. In contrast to the mRNA expression levels, IR-ET levels in the medium of T98G cells treated with a combination of three cytokines were rather decreased under hypoxia compared with those in normoxia. These findings indicate that hypoxia induces ET-1 mRNA expression in the treatment of three cytokines, but IR-ET levels in the medium do not reflect this induction in T98G glioblastoma cells.
This study aimed at increasing the pyruvate productivity from a multi-vitamin auxotrophic yeast Torulopsis glabrata, by increasing the availability of NAD+. We examined two strategies for increasing availability of NAD+. To supplement nicotinic acid (NA), the precursor of NAD+; and to increase the activity of alcohol dehydrogenase integrating with addition acetaldehyde as exterior electron acceptor. The addition of 8 mg l(-1) NA to the fermentation medium resulted in a significant increase in the glucose consumption rate (48.4%) and the pyruvate concentration (29%). An ethanol-utilizing mutant WSH-13 was screened and selected after nitrosoguanidine mutagenesis of the parent strain T. glabrata CCTCC M202019. Compared with the parent strain, the alcohol dehydrogenase activity of the mutant WSH-13 increased about 110% and the mutant could utilize ethanol as the sole carbon source for growth (1.8 g l(-1) dry cell weight). When growing with glucose, the addition of 4 mg l(-1) acetaldehyde to the mutant WSH-13 culture broth led to a significant increase in the glucose consumption rate (26.3%) and pyruvate production (22.5%), but the ratio of NADH/NAD+ decreased to 0.22. Acetaldehyde did not affect the glucose and energy metabolism at high dissolved oxygen (DO) concentration. However, at lower DO concentration (20%), maintaining the acetaldehyde concentration in the mutant culture broth at 4 mg l(-1) caused an increased NAD+ concentration but a decreased NADH concentration. As a consequence, the pyruvate production rate, the pyruvate yield on glucose and the pyruvate concentration were 68, 44 and 45% higher, respectively, than the corresponding values of the control (without acetaldehyde). The strategy for increasing the glycolytic flux and the pyruvate productivity in T. glabrata by increasing the availability of NAD+ may provide an alternative approach to enhance the metabolites productivity in yeast.
Lactobacillus salivarius subsp. salivarius strain UCC118 is a bacteriocin-producing strain with probiotic characteristics. The 2.13-Mb genome was shown by sequencing to comprise a 1.83 Mb chromosome, a 242-kb megaplasmid (pMP118), and two smaller plasmids. Megaplasmids previously have not been characterized in lactic acid bacteria or intestinal lactobacilli. Annotation of the genome sequence indicated an intermediate level of auxotrophy compared with other sequenced lactobacilli. No single-copy essential genes were located on the megaplasmid. However, contingency amino acid metabolism genes and carbohydrate utilization genes, including two genes for completion of the pentose phosphate pathway, were megaplasmid encoded. The megaplasmid also harbored genes for the Abp118 bacteriocin, a bile salt hydrolase, a presumptive conjugation locus, and other genes potentially relevant for probiotic properties. Two subspecies of L. salivarius are recognized, salivarius and salicinius, and we detected megaplasmids in both subspecies by pulsed-field gel electrophoresis of sizes ranging from 100 kb to 380 kb. The discovery of megaplasmids of widely varying size in L. salivarius suggests a possible mechanism for genome expansion or contraction to adapt to different environments.
This study aimed at increasing the pyruvate productivity of a multi-vitamin auxotrophic yeast Torulopsis glabrata by redirecting NADH oxidation from adenosine triphosphate (ATP)-production pathway (oxidative phosphorylation pathway) to non-ATP production pathway (fermentative pathway). Two respiratory-deficient mutants, RD-17 and RD-18, were screened and selected after ethidium bromide (EtBr) mutagenesis of the parent strain T. glabrata CCTCC M202019. Compared with the parent strain, cytochrome aa (3) and b in electron transfer chain (ETC) of RD-18 and cytochrome b in RD-17 were disrupted. As a consequence, the activities of key ETC enzymes of the mutant RD-18, including F(0)F(1)-ATP synthase, complex I, complex I + III, complex II + III, and complex IV, decreased by 22.2, 41.6, 53.1, 23.6, and 84.7%, respectively. With the deficiency of cytochromes in ETC, a large amount of excessive cytosolic NADH was accumulated, which hampered the further increase of the glycolytic flux. An exogenous electron acceptor, acetaldehyde, was added to the strain RD-18 culture to oxidize the excessive NADH. Compared with the parent strain, the concentration of pyruvate and the glucose consumption rate of strain RD-18 were increased by 26.5 and 17.6%, respectively, upon addition of 2.1 mM of acetaldehyde. The strategy for increasing the glycolytic flux in T. glabrata by redirecting the NADH oxidation pathway may provide an alternative approach to enhance the glycolytic flux in yeast.
Adrenomedullin (AM), a potent vasodilator peptide, has been suggested to act against cardiovascular complications and insulin resistance in the metabolic syndrome. We have already reported the AM gene repression in the early phase of adipocyte differentiation of NIH 3T3-L1 cells. Here we show adipocyte differentiation-related regulatory element for AM gene repression (ADRE-AR) in 36-bp region (-2135/-2100) of the AM gene. 3T3-L1 cells were induced to differentiate to adipocytes by insulin, dexamethasone and 3-isobutyl-1-methylxanthine. On the third day of differentiation, the promoter function was analyzed using the reporter plasmids, which contain the promoter region of AM gene (-4616/+108) in pGL3-basic luciferase reporter vector. The promoter activity decreased to about 20% in 3T3-L1 adipocytes when compared with 3T3-L1 preadipocytes, and a 36-bp region (-2135 to -2100) upstream from the transcription initiation site of the AM gene was necessary for higher AM gene expression in preadipocytes. This 36-bp ADRE-AR contains three copies of G/AAAA sequence (5'-GAAATGAAAGTAAAA-3') (-2124/-2110), which are conserved between mouse and human, and the introduction of mutations in each copy of G/AAAA sequence decreased the promoter activity in preadipocytes and adipocytes. Electrophoretic mobility shift assay showed that the full-length ADRE-AR was specifically bound by a certain nuclear protein(s). The present study has raised the possibility that ADRE-AR may play important roles in the AM gene expression in preadipocytes, and that the AM gene may be repressed through the ADRE-AR in adipocytes.