Tigliane-and daphnane-type diterpenoids from the buds of Daphne genkwa with their cytotoxic activities.

Two new tigliane- and daphnane-type diterpenoids, given the trivial names daphnegens A-B (1-2) were isolated from the buds of Daphne genkwa. Their structures were assigned on the basis of extensive spectroscopic. The absolute configurations of both compounds were determined by comparison of their calculated and experimental CD curves. In addition, compounds 1-2 were tested for their cytotoxic activities against MCF-7 and HepG-2 human cancer cell lines, and compound 2 showed remarkable cytotoxic activity against HepG-2 cell line with the IC50 value of 11.5 µM.

HOTAIR/Sp1/miR-199a critically regulates cancer stemness and malignant progression of cutaneous squamous cell carcinoma.

The long non-coding RNA (lncRNA), HOX antisense intergenic RNA (HOTAIR) is a well-characterized oncogene in multiple human cancers, but not in cutaneous squamous cell carcinoma (CSCC). In this study, we focused on investigating the potential role of HOTAIR in stemness of CSCC. By measuring its expression using RT-qPCR in CSCC vs. normal tissues, as well as in CSCC cell lines A431 or SCC13, A431- or SCC13-derived CSCC stem cells (CSCSCs), and normal skin fibroblasts (HSFs), we detected higher expression of HOTAIR in CSCC than in normal tissues, in recurrent than in non-recurrent CSCC tissues, in CSCCs and CSCSCs than in HSFs, and particularly, in CSCSCs than in CSCCs. Kaplan-Meier analysis suggested that higher expression of HOTAIR was positively correlated with worse overall survival of CSCC patients. Functional assays on colony formation, EdU incorporation, sphere formation, western blot on stem-cell biomarkers, and in vivo models showed that HOTAIR was essential in maintaining multiple stem cell phenotypes of CSCSCs in vitro and in vivo xenograft growth as well as metastasis. Mechanistically, HOTAIR directly interacted with and up-regulated Sp1. Sp1 then induced DNMT1-mediated promoter methylation and direct transcriptional repression of miR-199a-5p. Targeting Sp1 or DNMT1 further boosted the in vivo anti-tumor and anti-metastasis activities of targeting HOTAIR. In conclusion, HOTAIR, by up-regulating Sp1 and targeting miR-199a, promotes stemness and progression of CSCC. Targeting HOTAIR, Sp1 or the underlying mechanisms may thus benefit CSCC treatment.

Impacts of anthropogenic disturbances on microbial community of coastal waters in Shenzhen, South China.

During the urbanization, human activities have brought great changes to marine biodiversity and microbial communities of coastal water. Shenzhen is a coastal city that has developed rapidly over the past four decades, but the microbial communities and metabolic potential in offshore water are still not well characterized. Here, 16S rRNA gene V4-V5 sequencing was conducted to determine the microbial components from coastal waters in twenty selected areas of Shenzhen. The results showed a significant difference on the microbial composition between the western and eastern waters. Samples from western coast had more abundant Burkholderiaceae, Sporichthyaceae, Aeromonadaceae, and Methylophilaceae compared to eastern coast, and at the genus level, Candidatus Aquiluna, Aeromonas, Arcobacter, Ottowia and Acidibacter were significantly higher in western waters. There was also a notable difference within the western sample group, suggesting the taxa-compositional heterogeneity. Moreover, analysis of environmental factors and water quality revealed that salinity, pH and dissolved oxygen were relatively decreased in western samples, while total nitrogen, total phosphorus, chemical oxygen demand, and harmful marine vibrio were significantly increased compared to eastern waters. The results suggest the coastal waters pollution is more serious in western Shenzhen than eastern Shenzhen and the microbial communities are altered, which can be associated with anthropogenic disturbances.

Identification of virion-associated transcriptional transactivator (VATT) of SGIV ICP46 promoter and their binding site on promoter.

BACKGROUND: Iridoviruses are large DNA viruses that cause diseases in fish, amphibians and insects. Singapore grouper iridovirus (SGIV) is isolated from cultured grouper and characterized as a ranavirus. ICP46 is defined to be a core gene of the family Iridoviridae and SGIV ICP46 was demonstrated to be an immediate-early (IE) gene associated with cell growth control and could contribute to virus replication in previous research. METHODS: The transcription start site (TSS) and 5'-untranslated region (5'-UTR) of SGIV ICP46 were determined using 5' RACE. The core promoter elements of ICP46s were analyzed by bioinformatics analysis. The core promoter region and the regulation model of SGIV ICP46 promoter were revealed by the construction of serially deleted promoter plasmids, transfections, drug treat and luciferase reporter assays. The identification of virion-associated transcriptional transactivator (VATT) that interact with SGIV ICP46 promoter and their binding site on promoter were performed by electrophoretic mobility shift assays (EMSA), DNA pull-down assays and mass spectrometry (MS). RESULTS: SGIV ICP46 was found to have short 5'-UTR and a presumptive downstream promoter element (DPE), AGACA, which locates at + 36 to + 39 nt downstream of the TSS. The core promoter region of SGIV ICP46 located from - 22 to + 42 nt relative to the TSS. VATTs were involved in the promoter activation of SGIV ICP46 and further identified to be VP12, VP39, VP57 and MCP. A 10-base DNA sequence "ATGGCTTTCG" between the TSS and presumptive DPE was determined to be the binding site of the VATTs. CONCLUSION: Our study showed that four VAATs (VP12, VP39, VP57 and MCP) might bind with the SGIV ICP46 promoter and be involved in the promoter activation. Further, the binding site of the VATTs on promoter was a 10-base DNA sequence between the TSS and presumptive DPE.

Targeting regulation of tryptophan metabolism for colorectal cancer therapy: a systematic review.

Colorectal cancer (CRC) is one of the most malignant cancers resulting from abnormal metabolism alterations. As one of the essential amino acids, tryptophan has a variety of physiological functions, closely related to regulation of immune system, central nervous system, gastrointestinal nervous system and intestinal microflora. Colorectal cancer, a type of high-grade malignancy disease, stems from a variety of factors and often accompanies inflammatory reactions, dysbacteriosis, and metabolic disorders. Colorectal cancer accompanies inflammation and imbalance of intestinal microbiota and affects tryptophan metabolism. It is known that metabolites, rate-limiting enzymes, and ARH in tryptophan metabolism are associated with the development of CRC. Specifically, IDO1 may be a potential therapeutic target in colorectal cancer treatment. Furthermore, the reduction of tryptophan amount is proportional to the poor quality of life for colorectal cancer patients. This paper aims to discuss the role of tryptophan metabolism in a normal organism and investigate the relationship between this amino acid and colorectal cancer. This study is expected to provide theoretical support for research related to targeted therapy for colorectal cancer. Furthermore, strategies that modify tryptophan metabolism, effectively inhibiting tumor progression, may be more effective for CRC treatment.

Ultra-performance liquid chromatography/mass spectrometry technology and high-throughput metabolomics for deciphering the preventive mechanism of mirabilite on colorectal cancer via the modulation of complex metabolic networks.

Colorectal cancer (CRC) is a highly virulent and malignant disease and always accompanied by metabolic disorders. Currently, there are no effective therapeutic drugs for the treatment of CRC. High-throughput metabolomics approaches have been used to unveil the metabolic pathways related to several diseases. In this study, ultra-performance liquid chromatography/mass spectrometry-based high-throughput metabolomics was used for deciphering the potential preventive mechanism of mirabilite on CRC via the modulation of the associated metabolic disorders; a total of 28 differential biomarkers, including indole acetaldehyde, 5-hydroxyindoleacetic acid, hypoxanthine, retinal, retinal ester, linoleic acid, stearic acid, 6-deoxocastasterone, 2-hydroxybutyric acid and LysoPC, were identified in the APCmin/+ mice. These differential biomarkers are involved in the tryptophan metabolism, glycerophospholipid metabolism and biosynthesis of unsaturated fatty acids. Note that these biomarkers and their disturbed metabolic pathways were also regulated by mirabilite. It has been found that the prevention of CRC by mirabilite is mainly associated with tryptophan metabolism; this study shows that high-throughput metabolomics can reveal the perturbed metabolic disorders targeted in the action mechanism of drug treatment.

Comparisons of the therapeutic effects of three different routes of bone marrow mesenchymal stem cell transplantation in cerebral ischemic rats.

Bone marrow mesenchymal stem cells (BMSCs) are mainly administered via three routes: intra-arterial, intravenous and intracerebral. It has been reported that BMSC administration via each route ameliorates the functional deficits after cerebral ischemia. However, there have been no comparisons of the therapeutic benefits of BMSC administration through different delivery routes. In this study, we injected BMSCs into a rat model of transient middle cerebral artery occlusion (MCAO) through the intra-arterial, intravenous, or intracerebral route at day 7 after MCAO. Control animals received only the vehicle. Neurological function was assessed at post-ischemic days (PIDs) 1, 7, 14, 21, 28 and 35 using behavioral tests (modified Neurological Severity Score (mNSS) and the adhesive removal test). At PID 35, the rat brain tissues were processed for histochemical and immunohistochemical staining. Our results showed that BMSC transplantation via the intra-arterial, intravenous, and intracerebral routes induced greater improvement in neurological functions than the control treatments; furthermore, the intra-arterial route showed the greatest degree and speed of neurological functional recovery. Moreover, BMSCs treatment through each route enhanced reconstruction of axonal myelination in the area of the corpus callosum on the infarct side of the cerebral hemisphere, increased the expression of SYN and Ki-67, and decreased the expression of Nogo-A in the brain. These effects were more apparent in the intra-arterial group than in the intravenous and intracerebral groups. These data suggest that BMSCs transplantation, especially through intra-arterial delivery, can effectively improve neurological function intra-arterial. The underlying mechanism may include the promotion of synaptogenesis, endogenous cell proliferation, and axonal regeneration.

Network pharmacology combined with functional metabolomics discover bile acid metabolism as a promising target for mirabilite against colorectal cancer.

In this study, a combination of network pharmacology and metabolomics was used to explore the mechanism by which mirabilite regulates bile acid metabolism in the treatment of colorectal cancer. The PharmMapper web server was applied to make preliminary predictions for the treatment targets of mirabilite and to predict the interaction between mirabilite and disease targets using Discovery Studio 2.5. Furthermore, the urine metabolic profile was analyzed by the UPLC-Q-TOF-MS technology. The original data were processed by Progenesis QI software and analyzed by multivariate pattern recognition, which allowed us to reveal the metabolic disturbance in colorectal cancer and explain the therapeutic effect of mirabilite. The network pharmacology results showed that mirabilite can act on the disease targets, and the sites of action include amino acid residues Arg-364 and Asp-533, as well as nucleotides TPC-11, DG-112 and DA-113. Based on metabolomics, potential biomarkers were found to lie in the relevant pathways of bile acid metabolism, such as taurine, chenodeoxycholic acid, cholic acid, and deoxycholic acid. The results showed that mirabilite could regulate the distribution of overall metabolic disturbance, and bile acid metabolism was the main targeted pathway. Additionally, we predicted the upstream targets by ingenuity pathway analysis and found that mirabilite played a significant role in regulating the bile acid-related biomarkers, which allowed comprehensive analysis of the effect of mirabilite on colorectal cancer. This study fully explained the role of mirabilite in inhibiting colorectal cancer, which mainly occurs through bile acid metabolism, via the approach of network pharmacology combined with functional metabolomics.

High-throughput lipidomics reveal mirabilite regulating lipid metabolism as anticancer therapeutics.

Altered lipid metabolism is an emerging hallmark of cancers. Mirabilite has a therapeutic effect on colorectal cancer (CRC); however, its metabolic mechanism remains unclear. This study aims to explore the potential therapeutic targets of mirabilite protection against colorectal cancer in APCmin/+ mice model. Oral administration of mirabilite was started from the ninth month, while the same dosage of distilled water was given to both the control group and the model group. Based on lipidomics, we collected serum samples of all mice at the 20th week and used a non-targeted method to identify the lipid biomarkers of CRC. Compared with C57BL/6J mice, the metabolic profile of CRC model mice was significantly disturbed, and we identified that 25 lipid-related biomarkers, including linoleic acid, 2-hydroxybutyric acid, 6-deoxocastasterone, hypoxanthine, PC(16:1), PC(18:4), and retinyl acetate, were associated with CRC. According to the abovementioned results, there were six lipid molecules with significant differences that can be used as new targets for handling of CRC through six metabolic pathways, namely, linoleic acid metabolism, retinol metabolism, propanoate metabolism, arachidonic acid metabolism, biosynthesis of unsaturated fatty acids and purine metabolism. Compared with the model group, the metabolic profiles of these disorders tend to recover after treatment. These results indicated that the lipid molecules associated with CRC were regulated by mirabilite. In addition, we identified seven key lipid molecules, of which four had statistical significance. After administration of mirabilite, all disordered metabolic pathways showed different degrees of regulation. In conclusion, high-throughput lipidomics approach revealed mirabilite regulating the altered lipid metabolism as anticancer therapeutics.

Investigation of Controllable Nanoscale Heat-Denatured Bovine Serum Albumin Films on Graphene.

Two-dimensional graphene devices are widely used for biomolecule detection. Nevertheless, the surface modification of graphene is critical to achieve the high sensitivity and specificity required for biological detection. Herein, native bovine serum albumin (BSA) in inorganic solution is denatured on the graphene surface by heating, leading to the formation of nanoscale BSA protein films adsorbed on the graphene substrate via π-stacking interactions. This technique yields a controllable, scalable, uniform, and high-coverage method for graphene biosensors. Further, the application of such nanoscale heat-denatured BSA films on graphene as a universal graphene biosensor platform is explored. The thickness of heat-denatured BSA films increased with heating time and BSA concentration but decreased with solvent concentration as confirmed by atomic force microscopy. The noncovalent interaction between denatured BSA films and graphene was investigated by Raman spectroscopy. BSA can act as a p-type and n-type dopant by modulating pH-dependent net charges on the layered BSA-graphene surface, as assessed by current-voltage measurements. Chemical groups of denatured BSA films, including amino and carboxyl groups, were verified by X-ray photoelectron microscopy, attenuated total reflectance-Fourier transform infrared spectra, and fluorescent labeling. The tailoring of the BSA-graphene surfaces through chemical modification, controlled thickness, and doping type via noncovalent interactions provides a controllable, multifunctional biosensor platform for molecular diagnosis without the possibility of nonspecific adsorption on graphene.

Highly sensitive enumeration of circulating tumor cells in lung cancer patients using a size-based filtration microfluidic chip.

Circulating tumor cells (CTCs) in the peripheral blood could serve as a surrogate marker for the diagnosis of cancer metastasis and for therapeutic evaluation. However, the separation and characterization of CTCs is technically challenging owing to the extremely low number of CTCs present. Here we developed a size-based and high-throughput microfluidic chip, which exploits filtration microchannels to isolate the relatively larger CTCs from the rest of the blood constituents. High isolation efficiency of our microfluidic chip was demonstrated with three lung cancer cell lines spiked in blood samples at an optimal flow rate of 0.4 mL/h. The average recovery rates of 96%, 95% and 92% were obtained for A549, SK-MES-1, and H446, respectively. To clinically validate the chip, we also employed it to isolate CTCs from 59 lung cancer patients. CTCs were detected in 96.7% of patients with the mean number of 18.6 cells/mL, which was significantly higher than normal controls (P<0.05). The work here indicates that the size-based microfluidic platform with the advantage of capturing tumor cells without reliance on cell surface expression markers can provide a novel, inexpensive and effective tool for CTC detection and evaluation of cancer status.

Reversible neurotoxicity of kanamycin on dorsal cochlear nucleus.

The time course of aminoglycoside neurotoxic effect on cochlear nucleus is still obscure. We examined dynamic pathological changes of dorsal cochlear nucleus (DCN) and investigated whether apoptosis or autophagy was upregulated in the neurotoxic course of kanamycin on DCN after kanamycin treatment. Rats were treated with kanamycin sulfate/kg/day at a dose of 500mg by subcutaneous injection for 10 days. Dynamic pathological changes, neuron density and neuron apoptosis of the DCN were examined at 1, 7, 14, 28, 56, 70 and 140 days after kanamycin treatment. The expressions of JNK1, DAPK2, Bcl-2, p-Bcl-2, Caspase-3, LC3B and Beclin-1 were also detected. Under transmission electron microscopy, the mitochondrial swelling and focal vacuoles as well as endoplasmic reticulum dilation were progressively aggravated from 1 day to 14 days, and gradually recovered from 28 days to 140 days. Meanwhile, both autophagosomes and autolysosomes were increased from 1 day to 56 days. Only few neurons were positive to the TUNEL staining. Moreover, neither the expressions of caspase-3 and DAPK2 nor neurons density of DCN changed significantly. LC3-II was drastically increased at 7 days. Beclin-1 was upgraded at 1 and 7 days. P-Bcl-2 increased at 1, 7, 14 and 28 days. JNK1 increased at 7 days, and Bcl-2 was downgraded at 140 days. LC3-B positive neurons were increased at 1, 7 and 14 days. These data demonstrated that the neurons damage of the DCN caused by kanamycin was reversible and autophagy was upregulated in the neurotoxic course of kanamycin on DCN through JNK1-mediated phosphorylation of Bcl-2 pathway.

The effect of overexpression of PGC-1α on the mtDNA4834 common deletion in a rat cochlear marginal cell senescence model.

Aging is a natural process usually defined as a progressive loss of function with an accumulation of senescent cells. The clinical manifestations of this process include age-related hearing loss (AHL)/presbycusis. Several investigations indicated the association between a mitochondrial common deletion (CD) (mtDNA 4977-bp deletion in humans, corresponding to 4834-bp deletion in rats) and presbycusis. Previous researches have shown that peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) is a key regulator of mitochondrial biogenesis and energy metabolism. However, the expression of PGC-1α in the inner ear and the possible effect of PGC-1α on presbycusis are not clear. Our data demonstrated the distribution of PGC-1α and its downstream transcription factors nuclear respiratory factor-1 (NRF-1), mitochondrial transcription factor A (Tfam) and nuclear factor κB (NF-κB) in marginal cells (MCs) for the first time. To explore the role of PGC-1α in cellular senescence, we established a model of marginal cell senescence harboring the mtDNA4834 common deletion induced by d-galactose. We also found that PGC-1α and its downstream transcription factors compensatorily increased in our cell senescence model. Furthermore, the overexpression of PGC-1α induced by transfection largely increased the expression levels of NRF-1 and TFAM and significantly decreased the expression level of NF-κB in the cell senescence model. And the levels of CD, senescent cells and apoptotic cells in the cell model decreased after PGC-1α overexpression. These results suggested that PGC-1α might protect MCs in this cell model from senescence through a nuclear-mitochondrial interaction and against apoptosis. Our study may shed light on the pathogenesis of presbycusis and provide a new therapeutic target for presbycusis.

[Association between angiotensin-converting enzyme and polymorphisms of N5, N10-methylenetetrahydrofolic acid reductase gene in patients with ischemic stroke].

OBJECTIVE: To explore the association between angiotensin-converting enzyme (ACE) and the polymorphisms of N5, N10-methylenetetrahydrofolic acid reductase (MTHFR) gene in patients with ischemic stroke (IS). METHODS: Totally 454 patients with IS (IS group) and 334 controls (control group) were recruited in our study. Their I/D polymorphisms of ACE gene and C677T polymorphisms of MTHFR gene were detected by PCR and denaturing high performance liquid chromatography. RESULTS: The frequencies of DD, ID, II and CC, CT, TT genotype in IS group were 22.5%, 43.4%, 34.1%, and 51.8%, 40.5%, 7.7%, respectively, and were 17.4%, 45.5%, 37.1% and 56.9%, 38.3%, 4.8% in the control group, respectively. DD genotype was associated with large-artery atherosclerosis (LAA), and TT genotype and T allele were associated with LAA and cardioembolism. Synergistic effects were found between TT and DD/ID DD genotypes in the pathogenesis of ischemic stroke. CONCLUSION: DD, TT genotype and T allele are risk factors of IS, and ACE gene and MTHFR gene have synergistic effects in the pathogenesis of IS.

[Relationship between angiotensin converting enzyme gene and ischemic stroke].

OBJECTIVE: To study relationship between angiotensin converting enzyme (ACE) gene and ischemic stroke (IS). METHODS: (1)Four hundred and fifty-four patients and 334 controls were recruited in our study, their I/D polymorphisms of ACE gene were detected by polymerase chain reaction (PCR) and denaturing high performance liquid chromatogram, and their risk factors of IS were recorded at the same time. (2)In addition, 29 stroke-prone spontaneously hypertensive rats (SHR-SP) and 40 Sprague-Dawley (SD) rats were enrolled, and hypoxia- apnoea animal models and simple apnoea animal models were used at the same time. Their plasma angiotensin II (Ang II) levels were determined. RESULTS: The frequencies of DD, ID and II genotype in IS patients were 22.5%, 43.4% and 34.1%, respectively, and 17.4%, 45.5% and 37.1%, respectively in controls. DD genotype was associated with large artery arteriosclerosis (LAA). Plasma Ang II level in SHR-SP group was (164.49+/-34.58) ng/L, and it was higher than that in control group [(150.92+/-24.92)ng/L] with no significant difference (P>0.05). Ang II levels in apnoea and hypoxia-apnoea group were (382.84+/-62.75) ng/L and (295.90+/-55.07) ng/L, respectively, and they were significantly higher than that in control group (all P<0.01). The relative risks of DD genotype and D alleles in IS patients with smoking, alcohol abuse, or with diabetes mellitus were higher than those in controls, but II genotype and I alleles were lower than those in controls. CONCLUSION: DD genotype is a risk factor for IS, Ang II takes part in the course of hypoxia-stress, and it is correlated with smoking, alcohol abuse and diabetes mellitus in the pathogenesis of IS.

[Relationship between methylenetrahydrofolate reductase gene and ischemic stroke].

OBJECTIVE: To study the relationship between methylenetrahydrofolate reductase (MTHFR) gene and ischemic stroke. METHODS: Four hundred and fifty four ischemic stroke patients were enrolled in the study. They were divided into large artery atherosclerosis (LAA), cardioembolism (CE), small artery occlusion (SAA), stroke of other determined etiology (SOE) and stroke of undetermined etiology (SUE) according to TOAST (Trail of ORG 10172 in Acute Stroke Treatment) criteria; and they were divided into mild, moderate and severe types ischemic stroke according to their scores of neurologic impairment. Three hundred and thirty four subjects, in whom hypertension, coronary heart disease, cerebral vascular disease, diabetes mellitus, cancer, renal failure etc. were excluded, served as controls in the study. Their C677T polymorphisms of MTHFR gene were determined with polymerase chain reaction (PCR) and denaturing high performance liquid chromatography (DHPLC), and their risk factors of ischemic stroke were recorded at the same time. RESULTS: The frequencies of CC, CT and TT genotype in ischemic stroke were 51.8%, 40.5% and 7.7%, respectively, and they were 56.9%, 38.3% and 4.8% respectively in controls. TT genotype and T allele were associated with LAA and CE, moderate type and severe type of ischemic stroke. The frequencies of TT genotype and T allele in ischemic stroke patients were significantly higher in those with smoking, alcohol abuse or diabetes mellitus than those in controls (all P<0.10), but CC genotype and C allele were significantly lower in them than those in controls (all P<0.05). On the other hand, all of genotypes and alleles in ischemic stroke patients with no history of smoking, alcohol abuse or diabetes mellitus were not significantly different from those in controls. CONCLUSION: TT genotype and T allele are risk factors for ischemic stroke. It exists interactions between smoking, alcohol abuse, diabetes mellitus and MTHFR gene in the pathogenesis of ischemic stroke.

[Detecting the polymorphism of methylenetetrahydrofolate reductase gene by denaturing high performance liquid chromatography].

OBJECTIVE: To establish a method for detecting the polymorphism of methylenetetrahydrofolate reductase gene (MTHFR). METHODS: The MTHFR was amplified, and the amplified products were detected by denaturing high performance liquid chromatography (DHPLC), and the amplified MTHFR was confirmed by sequencing and restriction enzyme digesting. RESULTS: A total of 334 individuals of Han people in southern China were recruited in our study, and their polymorphisms of MTHFR were detected. The accurate rate of the DHPLC method, that was very sensitive with 100% detection rate available, was over 99%. The frequencies of CC, CT and TT genotypes were 56.9%, 38.3% and 4.8% individually, and the frequencies of T and C alleles were 23.95% and 76.05% individually. CONCLUSION: The DHPLC method can detect polymorphism of MTHFR rapidly, effectively and economically. And there is the existence of different MTHFR polymorphisms in area and race.

[Expression of xylanase gene xynA from Streptomyces olivaceoviridis A1 in Escherichia coli and Pichia pastoris].

The gene xynA encoding xylanase was cloned from Streptomyces olivaceoviridis A1. The xynA with and without origin signal peptide sequence were fused behind pel B signal peptide in the plasmid pET-22b(+) respectively, then transfered into the host E. coli. The xylanase expressed in E. coli had normal bioactivity. Further, the xynA without origin signal peptide sequence was cloned into the plasmid pPIC9 under the control of AOX1 promoter and introduced into the host Pichia pastoris by electroporation. The results of SDS-PAGE and activity assay of the xylanase expressed by recombinant P. pastoris showed that the xynA had been overexpressed and secreted, and the xylanase expressed had normal bioactivity. The expression level of xylanase in recombinant P. pastoris exceeded 0.2mg/mL in shake culture.