[Anti-tumor activity of HIS-4,a biflavonoid from Resina draconis,on human hepatoma HepG2 and SK-HEP-1 cells].

The research of anti-hepatocellular carcinoma(HCC) drug has attracted more and more attention. Natural products are the important source of active compounds for cancer treatment. A biflavonoid HIS-4 was isolated from Resina draconis in our previous study. MTT assay, hoechst staining, and flow cytometry analysis were used to investigate the effects of HIS-4 on the proliferation and apoptosis of human hepatoma HepG2 and SK-HEP-1 cells. Moreover, the effects of HIS-4 on the migration and invasion ability of HepG2 and SK-HEP-1 cells were evaluated by wound healing assay and Transwell assay. In addition, MTT assay, flow cytometry analyses, Hoechst staining, wound healing assay, Transwell assay, and tube formation assay were used to explore the anti-angiogenic activity of HIS-4 in human umbilical vein endothelial cells(HUVECs). Mechanistically, the HIS-4 regulatory of signal pathways in H9 epG2 and SK-HEP-1 cells were analyzed by Western blot. This results showed that HIS-4 suppressed the proliferation of human hepatoma HepG2 and SK-HEP-1 cells. Moreover HIS-4 induced their apoptosis of HepG2 and SK-HEP-1 cells. HIS-4 inhibited the migration and invasion of HepG2 and SK-HEP-1 cells. Additionally, HIS-4 exhibited angiogenesis effects. Mechanistically, up-regulation of MAPK signaling pathway and down-regulation of mTOR signaling pathway may be responsible for anti-hepatoma activity of HIS-4. Therefore, HIS-4 may be a promising candidate drug for HCC treatment.

Anti-tumor activity of HIS-4,a biflavonoid from Resina draconis,on human hepatoma HepG2 and SK-HEP-1 cells / 中国中药杂志

The research of anti-hepatocellular carcinoma(HCC) drug has attracted more and more attention. Natural products are the important source of active compounds for cancer treatment. A biflavonoid HIS-4 was isolated from Resina draconis in our previous study. MTT assay, hoechst staining, and flow cytometry analysis were used to investigate the effects of HIS-4 on the proliferation and apoptosis of human hepatoma HepG2 and SK-HEP-1 cells. Moreover, the effects of HIS-4 on the migration and invasion ability of HepG2 and SK-HEP-1 cells were evaluated by wound healing assay and Transwell assay. In addition, MTT assay, flow cytometry analyses, Hoechst staining, wound healing assay, Transwell assay, and tube formation assay were used to explore the anti-angiogenic activity of HIS-4 in human umbilical vein endothelial cells(HUVECs). Mechanistically, the HIS-4 regulatory of signal pathways in H9 epG2 and SK-HEP-1 cells were analyzed by Western blot. This results showed that HIS-4 suppressed the proliferation of human hepatoma HepG2 and SK-HEP-1 cells. Moreover HIS-4 induced their apoptosis of HepG2 and SK-HEP-1 cells. HIS-4 inhibited the migration and invasion of HepG2 and SK-HEP-1 cells. Additionally, HIS-4 exhibited angiogenesis effects. Mechanistically, up-regulation of MAPK signaling pathway and down-regulation of mTOR signaling pathway may be responsible for anti-hepatoma activity of HIS-4. Therefore, HIS-4 may be a promising candidate drug for HCC treatment.

[Construction and high-density fermentation of alkaline pectate lyase high-yield yeast].

Pectate lyase is widely applied in ramie degumming and fabric bioscouring in the textile industry. Compared to conventional processes that involve high alkaline and high temperature treatment, enzyme based treatments have significant advantages in fibers protectiveness, improved efficiency of refining, reduced energy consumption and pollution. Hence, it would be highly desirable to construct high-yield alkaline pectate lyase engineered strains and reduce the pectate lyase production cost. In the previous study, pectate lyase gene pel from Bacillus subtilis168 was expressed in Pichia pastoris GS115 after codon usage optimization based on the vector pHBM905A. To improve the expression level, the vector pHBM905BDM with optimized promoter and signal peptide was used to express the optimized gene pels in GS115. The transformant had increased activity from 68 U/mL to 100 U/mL with the improvement in the transcription level by 27% measured by qPCR. The transformants were further screened on pectin plates, where higher halo forming strains were picked for shake-flask fermentation and strain GS115-pHBM905BDM-pels4 showed the highest activity of 536 U/mL. Then plasmid pPIC9K-pels was constructed and electroporated into the GS115-pHBM905BDM-pels4 cells. Subsequently, high-copy transformant was screened by using the medium containing antibiotics G418, strain GS115-pHBM905BDMpPIC9K- pels1 was identified with increased activity of 770 U/mL and the copy number of pels was 7 confirmed by qPCR. Finally, the activity of pectate lyase produced by GS115-pHBM905BDM-pPIC9K-pels1reached to 2 271 U/mL in a 5-L fermentor. The activity of pectate lyase in our study reached the highest level of expression in P. pastoris, showing good application potential in the textile industry.

Construction and high-density fermentation of alkaline pectate lyase high-yield yeast / 生物工程学报

Pectate lyase is widely applied in ramie degumming and fabric bioscouring in the textile industry. Compared to conventional processes that involve high alkaline and high temperature treatment, enzyme based treatments have significant advantages in fibers protectiveness, improved efficiency of refining, reduced energy consumption and pollution. Hence, it would be highly desirable to construct high-yield alkaline pectate lyase engineered strains and reduce the pectate lyase production cost. In the previous study, pectate lyase gene pel from Bacillus subtilis168 was expressed in Pichia pastoris GS115 after codon usage optimization based on the vector pHBM905A. To improve the expression level, the vector pHBM905BDM with optimized promoter and signal peptide was used to express the optimized gene pels in GS115. The transformant had increased activity from 68 U/mL to 100 U/mL with the improvement in the transcription level by 27% measured by qPCR. The transformants were further screened on pectin plates, where higher halo forming strains were picked for shake-flask fermentation and strain GS115-pHBM905BDM-pels4 showed the highest activity of 536 U/mL. Then plasmid pPIC9K-pels was constructed and electroporated into the GS115-pHBM905BDM-pels4 cells. Subsequently, high-copy transformant was screened by using the medium containing antibiotics G418, strain GS115-pHBM905BDMpPIC9K- pels1 was identified with increased activity of 770 U/mL and the copy number of pels was 7 confirmed by qPCR. Finally, the activity of pectate lyase produced by GS115-pHBM905BDM-pPIC9K-pels1reached to 2 271 U/mL in a 5-L fermentor. The activity of pectate lyase in our study reached the highest level of expression in P. pastoris, showing good application potential in the textile industry.

Apparent Epigenetic Meiotic Double-Strand-Break Disparity in Saccharomyces cerevisiae: A Meta-Analysis.

Previously published, and some unpublished, tetrad data from budding yeast (Saccharomyces cerevisiae) are analyzed for disparity in gene conversion, in which one allele is more often favored than the other (conversion disparity). One such disparity, characteristic of a bias in the frequencies of meiotic double-strand DNA breaks at the hotspot near the His4 locus, is found in diploids that undergo meiosis soon after their formation, but not in diploids that have been cloned and frozen. Altered meiotic DNA breakability associated with altered metabolism-related chromatin states has been previously reported. However, the above observations imply that such differing parental chromatin states can persist through at least one chromosome replication, and probably more, in a common environment. This conclusion may have implications for interpreting changes in allele frequencies in populations.

Efficient cleavage of DNA oligonucleotides by a non-FokI-type zinc finger nuclease containing one His4-type finger domain derived from the first finger domain of Sp1.

In this study, we sought to improve the hydrolytic activity of a His4-type single finger domain (f2), which was previously derived from the second finger domain (f2') of the Sp1 zinc finger protein (Sp1wt), which has 3 tandem finger domains (f1', f2', and f3'). To this end, 2 His4-type single finger domains were generated by mutating 2 Cys residues participating in Zn(II) coordination with the His residues in the first (f1') and third finger (f3') domains of Sp1wt. Circular dichroism spectroscopy results showed that the first and second His4-type zinc finger domains (f1 and f2) adopted folded ßßα structures in the presence of Zn(II), but that the third His4-type zinc finger domain (f3) did not. Non-FokI-type zinc finger nucleases containing 3 or 4 finger domains were also prepared by combining a His4-type zinc finger domain with the Sp1wt scaffold. We studied their DNA-binding abilities and hydrolytic activities against DNA oligonucleotides by performing gel-mobility-shift assays. The results showed that f1 had higher hydrolytic activity for a DNA oligonucleotide with a GC box (5'-GGG GCG GGG-3'), compared with that of f2, although both His4-type single finger domains had similar DNA-binding affinities. The difference in the hydrolytic activity between f1 and f2 was ascribed not only to the zinc coordinate structure, but also to its folding structure and the stability of finger domain.