Screening and identification of osimertinib resistance gene ferredoxin 1 in nci-h1975 cells / 中国药理学与毒理学杂志

OBJECTIVE To study the potential resistance gene and molecular mechanism of osimertinib in non-small cell lung cancer cells. METHODS Using genome-wide CRISPR/Cas9-based screening, we identified the potential resistance gene ferredoxin 1 (FDX1) from NCI-H1975 cells. Then, the stable cell lines sg-FDX1 and sg-adeno-associated virus integration sitel (sg-AAVS1) were established after knockout of FDX1 and AAVS1 as control. Genomic DNA was extracted from sg-FDX1 cells and the DNA sequences on both sides of the sgRNA were amplified and connected to the T carrier for sequencing. Western blotting was used to detect the protein expression levels of FDX1 at the same time. sg-FDX1 or sg-AAVS1 cells were treated with osimertinib at 0, 30, 50 and 100 nmol-L'1 for 30 h and the expression levels of cleaved poly (ADP-ribose) polymerase (c-PARP), phosphorylation of epidermal growth factor receptor (p-EGFR) and phosphorylation of extracellular regulated protein kinases (ERK) were detected by Western blotting. The clones were grown to about 10 cells that were treated with osimertinib at 12 nmol-L'1 for 10 d, and the number of clones with ≥10 cells was counted under the microscope using the plate cloning assay. CCK8 assay was used to detect the survival rate of tumor cells after they were treated with osimertinib from 0 to 30 nmol • L-1 for 72 h, or 30 nmol • L-1 for 3, 5 and 7 d. RESULTS Sequencing results showed that FDX1 gene was deleted and FDX1 expression was knocked out effectively. The level of c-PARP expression was significantly reduced in sg-FDX1 cells, compared with sg-AAVS1 cells after osimertinib 50 nmol-L-1 treatment (P<0.01). The inhibition of osimertinib on phosphorylation level of EGFR and ERK was reduced in sg-FDX1 cells, compared with sg-AAVS1 cells (P<0.01). Cloning formation and CCK8 experiments showed that osimertinib inhibition on cloning formation rate and proliferation rate were decreased significantly in sg-FDX1 cells compared with sg-AAVS1 cells (P<0.05). CONCLUSION NCI-H1975 cells with FDX1 knockout can weaken osimertinib-induced apoptosis, which accounts for the mechanism by which FDX1 is involved in the resistance of NCI-H1975 cells to osimertinib.

Molecular and functional characterization of ferredoxin NADP(H) oxidoreductase from Gracilaria chilensis and its complex with ferredoxin

BACKGROUND: Ferredoxin NADP(H) oxidoreductases (EC 1.18.1.2) (FNR) are flavoenzymes present in photosynthetic organisms; they are relevant for the production of reduced donors to redox reactions, i.e. in photosynthesis, the reduction of NADP+ to NADPH using the electrons provided by Ferredoxin (Fd), a small FeS soluble protein acceptor of electrons from PSI in chloroplasts. In rhodophyta no information about this system has been reported, this work is a contribution to the molecular and functional characterization of FNR from Gracilaria chilensis, also providing a structural analysis of the complex FNR/Fd. METHODS: The biochemical and kinetic characterization of FNR was performed from the enzyme purified from phycobilisomes enriched fractions. The sequence of the gene that codifies for the enzyme, was obtained using primers designed by comparison with sequences of Synechocystis and EST from Gracilaria. 5'RACE was used to confirm the absence of a CpcD domain in FNRPBS of Gracilaria chilensis. A three dimensional model for FNR and Fd, was built by comparative modeling and a model for the complex FNR: Fd by docking. RESULTS: The kinetic analysis shows KMNADPH of 12.5 M and a kcat of 86 s-1, data consistent with the parameters determined for the enzyme purified from a soluble extract. The sequence for FNR was obtained and translated to a protein of 33646 Da. A FAD and a NADP+ binding domain were clearly identified by sequence analysis as well as a chloroplast signal sequence. Phycobilisome binding domain, present in some cyanobacteria was absent. Transcriptome analysis of Gch revealed the presence of two Fd; FdL and FdS, sharing the motif CX5CX2CX29X. The analysis indicated that the most probable partner for FNR is FdS. CONCLUSION: The interaction model produced, was consistent with functional properties reported for FNR in plants leaves, and opens the possibilities for research in other rhodophyta of commercial interest.

Introducing nitazoxanide as a promising alternative treatment for symptomatic to metronidazole-resistant giardiasis in clinical isolates

Objective To identify the frequencies (F) of ferredoxin and nitroreductase mutations on Iranian clinical isolates of Giardia lamblia in order to predict whether the nitazoxanide can be prescribed as suitable drug for symptomatic to metronidazole-resistant giardiasis. Methods Forty Giardia lamblia isolates as of 38 symptomatic and two metronidazole-resistant patients were collected from Iran. DNAs were extracted and amplified by targeting ferredoxin and GlNR genes. The amplicons were directly sequenced to determine gene mutations. Results The various amino acid substitutions (F: 20%, Haplotype diversity: 0.891, Tajima's D: −0.440 13) were identified by analyzing ferredoxin gene in four symptomatic and two resistant isolates. Only two haplotypes (F: 5%, HD: 0.345; Tajima's D: 0.778 15) characterized in metronidazole-resistant isolates of GlNR, however, no point mutations was found in symptomatic isolates. Conclusions Non-synonymous mutations of ferredoxin oxidoreductase gene reduce translational regulatory protein's binding affinity which concludes reduction of ferredoxin expression and its activity. This leads to decrease in metronidazole drug delivery into the cells. Mutations in these isolates may lead to their resistance to metronidazole. No to low synonymous mutations of GlNR demonstrates that nitazoxanide can be prescribed as promising alternative treatment for symptomatic to metronidazole-resistant giardiasis in Iranian clinical isolates.

Influence of 120 kDa Pyruvate:Ferredoxin Oxidoreductase on Pathogenicity of Trichomonas vaginalis

Trichomonas vaginalis is a flagellate protozoan parasite and commonly infected the lower genital tract in women and men. Iron is a known nutrient for growth of various pathogens, and also reported to be involved in establishment of trichomoniasis. However, the exact mechanism was not clarified. In this study, the author investigated whether the 120 kDa protein of T. vaginalis may be involved in pathogenicity of trichomonads. Antibodies against 120 kDa protein of T. vaginalis, which was identified as pyruvate:ferredoxin oxidoreductase (PFOR) by peptide analysis of MALDI-TOF-MS, were prepared in rabbits. Pretreatment of T. vaginalis with anti-120 kDa Ab decreased the proliferation and adherence to vaginal epithelial cells (MS74) of T. vaginalis. Subcutaneous tissue abscess in anti-120 kDa Ab-treated T. vaginalis-injected mice was smaller in size than that of untreated T. vaginalis-infected mice. Collectively, the 120 kDa protein expressed by iron may be involved in proliferation, adhesion to host cells, and abscess formation, thereby may influence on the pathogenicity of T. vaginalis.

Introducing nitazoxanide as a promising alternative treatment for symptomatic to metronidazole-resistant giardiasis in clinical isolates

OBJECTIVE@#To identify the frequencies (F) of ferredoxin and nitroreductase mutations on Iranian clinical isolates of Giardia lamblia in order to predict whether the nitazoxanide can be prescribed as suitable drug for symptomatic to metronidazole-resistant giardiasis.@*METHODS@#Forty Giardia lamblia isolates as of 38 symptomatic and two metronidazole-resistant patients were collected from Iran. DNAs were extracted and amplified by targeting ferredoxin and GlNR genes. The amplicons were directly sequenced to determine gene mutations.@*RESULTS@#The various amino acid substitutions (F: 20%, Haplotype diversity: 0.891, Tajima's D: -0.44013) were identified by analyzing ferredoxin gene in four symptomatic and two resistant isolates. Only two haplotypes (F: 5%, HD: 0.345; Tajima's D: 0.77815) characterized in metronidazole-resistant isolates of GlNR, however, no point mutations was found in symptomatic isolates.@*CONCLUSIONS@#Non-synonymous mutations of ferredoxin oxidoreductase gene reduce translational regulatory protein's binding affinity which concludes reduction of ferredoxin expression and its activity. This leads to decrease in metronidazole drug delivery into the cells. Mutations in these isolates may lead to their resistance to metronidazole. No to low synonymous mutations of GlNR demonstrates that nitazoxanide can be prescribed as promising alternative treatment for symptomatic to metronidazole-resistant giardiasis in Iranian clinical isolates.

Biological effect of down-regulating of MTRR gene on cisplatin-resistant ovarian cancer SKOV3 cells in vitro and in vivo studies / 中华妇产科杂志

Objective To study the biological effects of down-regulatingof methionine synthase reductase (MTRR) gene on cisplatin resistant ovarian cancer SKOV3/DDP cell in vitro and in vivo. Methods (1) Establishing the cell line of MTRR down-regulated. Four short hairpin RNA (shRNA) for MTRR gene (U6-GFP-Neo-homo-1106, U6-GFP-Neo-homo-1931, U6-GFP-Neo-homo-419, U6-GFP-Neo-homo-1460) were designed respectively. Western blot was used to detect the interference efficiency and selected the most efficient shRNA. The MTRR 1106 was selected as the best silencing effect of interference fragment and then therecombinant plasmid vector pSicoR-1106 was constructed and transfected into SKOV3/DDP cells.The stably transfected cells was obtained by screening of flow cytometry(FCM).Fluorescence quantitative reverse transcription (RT)-PCR and western blot were used to detect the expression of MTRR mRNA and protein. (2) Study in vitro: recombinant plasmid expression vector pSicoR-1106, pSicoR-NC and packaging plasmid were respectively transfected into 293T cell. SKOV3/DDP cells were transfected by viral supernatant. The experiment was divided into three groups, namely SKOV3/DDP-MTRRi (down-regulated MTRR group), SKOV3/DDP-NC (negative control group), and the SKOV3/DDP (blank control group). The cell growth curves and half maximal inhibitory concentration (IC50) of cisplatin were made by methyl thiazolyl tetrazolium (MTT) method. Three groups cells were treated with different concentration of cisplatin (0, 1, 2 and 4 μg/ml). The clonogenicity efficiency was observed by clony formation test. The cell cycles were measured by FCM . (3) Study in vivo: three groups cells were subcutaneously inoculated into the nude mice to develop a tumor model. Mice were injected intraperitoneally with cisplatin at 2.5 mg/kg (once every 2 days, in 21 rounds), then the tumor growth was observed. The expression of MTRR and proliferation-related Ki-67 antigen by immunohistochemistry in xenograft tumors were measured. Results (1) Results showed that U6-GFP-Neo-homo-1106 was the best shRNA with interference effect to MTRR. The recombinant plasmid pSicoR-1106 was constructed and transfected into SKOV3/DDP. The MTRR mRNA and protein were down-regulated after transfected. This result showed that MTRR down-regulated SKOV3/DDP cell line was constructed successfully. (2) The cell growth curves showed that the growth of SKOV3/DDP-MTRRi cells were significantly decreased compared with that in the SKOV3/DDP-NC cells and SKOV3/DDP cells (P<0.05). The IC50 of SKOV3/DDP-MTRRi, SKOV3/DDP-NC and SKOV3/DDP were 4.01, 7.90, and 8.91 μg/ml, respectively. The IC50 of SKOV3/DDP-MTRRi was significantly lower than that in control cell groups (P<0.05).Clony formation tests showed that the clony numbers of varied concentration of cisplatin of SKOV3/DDP-MTRRi were significantly less than those of SKOV3/DDP-NC cells and SKOV3/DDP cells (P<0.05). FCM showed that when the cisplatin concentration rose to 4 μg/ml, the G0/G1 phase cell ratio in SKOV3/DDP-MTRRi cells group was (72.8±5.0)%, which was significantly higher than those in the SKOV3/DDP-NC cells group and SKOV3/DDP cells group [(64.4±2.5)%and (64.3±3.0)%], respectively (all P<0.05).(3) Six weeks after nude mice intraperitoneal injection with cisplatin, the tumor volume of SKOV3/DDP-MTRRi, SKOV3/DDP-NC and SKOV3/DDP were respectively (97 ± 32), (168 ± 45), and (173 ± 32) mm3, the tumor weight were (0.36±0.17), (1.08±0.17), and (1.11±0.20) g, in which tumor volume and weight of SKOV3/DDP-MTRRi were significantly less than those of SKOV3/DDP-NC cells and SKOV3/DDP cells (all P<0.05). In three groups tumor tissue, positive rates of MTRR were respectively 2/8, 5/8, and 7/8, the positive rates of Ki-67 were respectively1/8, 6/8, and 7/8, in which SKOV3/DDP-MTRRi was significantly lower those SKOV3/DDP-NC cells and SKOV3/DDP cells (all P<0.05). Conclusion The growth and cisplatin resistance of ovarian cancer cells could be decreased by down-expressing of MTRR gene in vitro and in vivo.

Effect of MTRR gene on apoptosis and autophagy pathways in multi-resistant epithelial ovarian cancer / 中华妇产科杂志

Objective To explore the effect of down-regulated methionine synthase reductase (MTRR) gene on the apoptosis and autophagy pathway, and offer a possible approach for the MTRR to reverse the multi-resistant ovarian cancer. Methods (1) The experiment was divided into 3 groups, SKOV3/DDP-MTRRi (down-regulated MTRR group), SKOV3/DDP-NC (negative control group), and SKOV3/DDP (blank control group). Different concentration of cisplatin (0, 1, 2, and 4 μg/ml) treated on 3 groups cells. The apoptosis rate was measured by flow cytometry (FCM). Autophagy was detected by immunofluorescence. Autophagy microtubule associated protein light chain 3β(LC3B) and p62 were detected by western blot. The formation of autophagosome of cells was observed by transmission electron microscope. (2) Detection of autophagy and apoptosis of SKOV3/DDP-MTRRi induced by rapamycin. The experiment was divided into 4 groups included rapamycin group (5 nmol/L rapamycin), rapamycin+cisplatin group (5 nmol/L rapamycin+4μg/ml cisplatin), cisplatin group (4μg/ml cisplatin) and blank control group. LC3B and p62 protein were detected by western blot. The survival rate cells were detected by methyl thiazolyl tetrazolium (MTT) method. The apoptosis rate was measured by FCM. (3) The 3 groups cells (SKOV3/DDP, SKOV3/DDP-NC and SKOV3/DDP-MTRRi) induced by a certain concentration of cisplatin (4 μg/ml) after 48 hours, then detecting the protein expression of caspase, Bcl-2 family in apoptosis pathway and the key proteins in phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt) autophagy pathways by western blot, getting the time when the proteins′expression changed. Results (1) The 3 groups cells (SKOV3/DDP, SKOV3/DDP-NC, and SKOV3/DDP-MTRRi) induced by a certain concentration of cisplatin (4 μg/ml) after 48 hours, apoptosis and autophagy of 3 groups of cells were gradually increased with the increased concentration of cisplatin. The apoptosis rate of SKOV3/DDP-MTRRi cells [(26.2 ± 1.4)%] were significantly increased compared with the SKOV3/DDP-NC cells or SKOV3/DDP cells [(14.8 ± 2.4)%, (14.2 ± 2.4)%;all P0.05), but cleaved caspase-3, cleaved caspase-7, cleaved caspase-9, and cleaved PARP were significantly increased in SKOV3/DDP-MTRRi cells (P<0.05). For the autophagy pathway, the expression of phosphorylated Akt (p-Akt) and phosphorylated mammalian target of rapamycin (p-mTOR) were significantly increased (P<0.05), but Akt and mTOR had no significant variation. The expression of phosphatase and tensin homologue deleted on chromosome ten (PTEN) was significantly decreased (P<0.05). Conclusions MTRR silencing significantly increase cisplatin-induced apoptosis and reduce the autophagy induced by cisplatin in SKOV3/DDP cells. Down-regulation of MTRR enhanced the chemosensitivity of cisplatin-resistant ovarian cancer cells may be by activating caspase and Bcl-2 apoptosis family and inhibiting the PI3K/Akt autophagy pathway.

Association of methionine synthase reductase gene polymorphism with unexplained recurrent spontaneous abortion / 中华妇产科杂志

Objective To explore the relationship between the polymorphism of methionine synthase reductase(MTRR) A66G and the susceptibility to unexplained repeated spontaneous abortion (URSA).Methods Total of 200 Henan Han couples with URSA (URSA group) and 76 Henan Han healthy couples without URSA (control group)were enrolled in this study.Their MTRR A66G genotypes were determined by PCR restriction fragment length polymorphism (PCR-RFLP).Results (1) The allele frequencies of MTRR A66G:the frequencies of allele A and allele G in URSA group were 76.5％ (153/200)in husband and 72.8％ (146/200) in wife,23.5％ (47/200) in husband and 27.2％ (54/200) in wife,respectively.The frequencies of allele A and allele G in control group were 78.9％ (60/76) in husband and 78.3％ (59/76) in wife,21.1％ (16/76) in husband and 21.7％ (16/76) in wife,respectively.The frequencies of allele A and allele G were not significantly different between female and male subjects within the same experimental group (P ＞ 0.05),and also there were not significantly different between the same gender subjects at URAS and control groups(P ＞ 0.05).(2) The genotype frequencies of MTRR A66G:the frequencies of genotype AA,AG and GG in URSA group were 57.0％ (114/200) in husband and 52.0％ (104/200) in wife,39.0％ (78/200) in husband and 41.5％ (83/200) in wife,4.0％ (8/200) in husband and 6.5％ (13/200) in wife,prepectively.The frequencies of genotype AA,AG and GG in control group were 59.2％ (45/76) in husband and 59.2％ (50/76) in wife,39.5％ (30/76) in husband and 38.2％ (29/76) in wife;1.3 ％ (1/76) in husband and 2.6％ (2/76) in wife,prepectively.The frequencies of genotype AA,AG and GG were not significantly different between female and male subjects within the same group (P ＞ 0.05),and also there were not significantly different between the same gender subjects at URSA and control groups (P ＞0.05).(3) Combined genotype of couples:the combined genotype frequencies of GG + GG,GG + AG,GG +AA,AG + AG,AG + AA and AA + AA in URSA group were 1.0％ (2/200),2.5％ (5/200),6.0％ (12/200),20.0％ (40/200),38.0％ (76/200),and 32.5 ％ (65/200),prepectively ; the combined genotype frequencies in control group were 0,1.3％ (1/76),2.6％ (2/76),17.1％ (13/76),42.1％ (32/76),36.8％ (28/76),prepectively.The combined genotype analysis between the two groups were also not significantly different (P ＞ 0.05).Conclusion The polymorphism of MTRR A66G gene was not associated with the susceptibility to URSA (P ＞ 0.05),and so it was not the inherited genetic risk factor of URSA.

Hydrogenosomal activity of Trichomonas vaginalis cultivated under different iron conditions

To evaluate whether iron concentration in TYM medium influence on hydrogenosomal enzyme gene expression and hydrogenosomal membrane potential of Trichomonas vaginalis, trophozoites were cultivated in irondepleted, normal and iron-supplemented TYM media. The mRNA of hydrogenosomal enzymes, such as pyruvate ferredoxin oxidoreductase (PFOR), hydrogenase, ferredoxin and malic enzyme, was increased with iron concentrations in T. vaginalis culture media, measured by RT-PCR. Hydrogenosomal membrane potentials measured with DiOC6 also showed similar tendency, e.g. T. vaginalis cultivated in iron-depleted and iron-supplemented media for 3 days showed a significantly reduced and enhanced hydrogenosomal membrane potential compared with that of normal TYM media, respectively. Therefore, it is suggested that iron may regulate hydrogenosomal activity through hydrogenosomal enzyme expression and hydrogenosomal membrane potential.

A New (2Fe-2S) Ferredoxin Gene from Trichomonas Vaginalis / 热带医学杂志

Objectives The ferredoxins are iron-sulfur proteins, which function in electron transfer reactions in a variety of systems and participate in the activation of the antimicrobial agent metronidazole. The aim of this study is to clone and characterize ferredoxin genes of Trichomonas vaginalis. Methods A cDNA expression library was constructed with T. Vaginalis total RNA. Hundreds of cDNA clones were isolated and sequenced. Sequence analysis was performed using BLAST programs, ClustalW program, etc. Results One of the cDNA clones, which has homology with T.vaginalis ferredoxin, was further analyzed. This cDNA clone has an open reading frame of 312 base pairs. The deduced precursor protein contains 103 amino acid residues with a hydrogenosome targeting sequence (MLSQCSPLRF) at the N-terminal end. The primary sequence analysis revealed that this new ferredoxin (TvFd2) has a high homology (69% identity) to the previous reported T.vaginalis ferredoxin(TvFd). Interestingly, TvFd2 is homologous to both the two subclasses of (2Fe-2S) ferredoxins, the oxidase ferredoxins and the photosynthetic ferredoxins,but with low similarity. The conserved four-cysteine residues, which are predicted to form the iron-sulfur cluster,are arranged in a typical pattern of (2Fe-2S)ferredoxins(-C-X5-C-X2-C-Xn-C-). Conclusion These data show that TvFd2 is a putative new (2Fe-2S) ferredoxin of T.vaginalis. Its biological function remains to be studied.

Mechanism of reductive photoactivation of enzymes of C4 pathway.

Light, besides initiating primary photochemical processes, alters the redox state of soluble components in chloroplast. The present review attempts to cover the mechanism of reductive photoactivation of enzymes of photosynthetic carbon reduction cycle using key enzymes as examples. The reduced soluble components — ferredoxin, thioredoxin and NADPH, in turn, cause the reduction of disulphides to dithiols of chloroplastic enzymes. NADP-malate dehydrogenase is subject to activation by light through changes in NADPH/NADP. The key enzyme of C4 photosynthesis-PEP carboxylase, though cytosolic, has been shown to be activated by disulphide/sulphhydryl interconversion by reductants generated in light through chloroplast electron transport flow. Pyruvate Pi dikinase activity is controlled by the adenylate energy charge. It remains unclear how light controls the activation of cytosolic enzymes.

Cloning of ferredoxin I gene from Azotobacter vinelandii using synthetic oligonucleotide probes.

Two synthetic oligonucleotide probe mixtures, whose sequences were inferred from two separate stretches of amino acids, one closer to the carboxy terminal and the other closer to the amino terminal, of ferredoxin I protein of Azotobacter vinelandii, were used to select ferredoxin I gene clones from a cosmid gene library of Azotobacter vinelandii. Restriction analysis revealed that 7 out of 10 selected clones were of the same type. All these clones were found to hybridize with fixABCX genes of Rhizobium meliloti.