Effect of Repetitive Bleeding on NADH-Cytochrome b_5 Methemoglobin Reductase Activity and Molybdenum Content in Erythrocytes of Rats

Reticulocytosls in rats was induced by repetitive bleeding. Both the in vitro and the in vivo studies showed that the detected reductive speed of methemoglobin of the bleeding group was faster than that of the control group at all time intervals. At the same time, the NADH-cytochrome b5 methemoglobin reductase activity and the molybdenum content in erythrocytes of the bleeding group were significantly increased. Regressional analysis showed that there was a significantly positive correlation between the enzyme activity and the molybdenum content. It is proposed that molybdenum might be required for the enzyme activity

Cytochrome b5 reductase 2 suppresses tumor formation in nasopharyngeal carcinoma by attenuating angiogenesis

Background:Cytochrome b5 reductase 2(CYB5R2) is a potential tumor suppressor that inhibits cell proliferation and motility in nasopharyngeal carcinoma(NPC).Inactivation of CYB5R2 is associated with lymph node metastasis in NPC.This study aimed to explore the mechanisms contributing to the anti-neoplastic effects of CYB5R2.Methods:Polymerase chain reaction(PCR) assays were used to analyze the transcription of 84 genes known to be involved in representative cancer pathways in the NPC cell line HONE1.NPC cell lines CNE2 and HONE1 were transiently transfected with CYB5R2,and data was validated by real-time PCR.A chick chorioallantoic membrane(CAM)embryo model was implanted with CYB5R2-expressing CNE2 and HONE1 cells to evaluate the effect of CYB5R2 on angiogenesis.An immunohistochemical assay of the CAM model was used to analyze the protein expression of vascular endothelial growth factor(VEGF).Results:In CYB5R2-transfected NPC cells,PCR assays revealed up-regulated mRNA levels of Fas cell surface death receptor(FAS),FBJ murine osteosarcoma viral oncogene homolog(FOS),phosphoinositide-3-kinase regulatory subunit 1(PIK3R1),integrin beta 3(ITGB3),metastasis suppressor 1(MTSSl),interferon beta 1(IFNB1),and cyclin-dependent kinase inhibitor 2A(CDKN2A) and down-regulated levels of integrin beta 5(ITGB5),insulin-like growth factor 1(IGF1),TEK tyrosine kinase(TEK),transforming growth factor beta receptor 1(TGFBRl),and VEGF.The angiogenesis in the CAM model implanted with CYB5R2-transfected NPC cells was inhibited.Down-regulation of VEGF by CYB5R2 in NPC cells was confirmed by immunohistochemical staining in the CAM model.Conclusion:CYB5R2 up-regulates the expression of genes that negatively modulate angiogenesis in NPC cells and down-regulates the expression of VEGF to reduce angiogenesis,thereby suppressing tumor formation.

丙基硫氧嘧啶对甲状腺NADH-细胞色素b_5还原酶活性影响

目的 探讨丙基硫氧嘧啶 (PTU)抗甲状腺作用新的药理机制。方法 以高铁氰化钾和二氯酚靛酚为底物测定NADH 细胞色素b5还原酶 (b5R)活性 ,应用高香草酸荧光分析技术对H2 O2 浓度进行测定 ,观察PTU对甲状腺b5R活性和H2 O2 浓度影响。结果 PTU可抑制b5R活性 ,且呈浓度依赖性 ,0 0 5mmol·L-1PTU即对b5R活性有抑制作用 ,以后随PTU浓度增加 ,b5R活性逐渐降低 ;H2 O2 浓度则随b5R活性降低而下降。NADH有拮抗PTU对b5R的抑制作用。结论 PTU对甲状腺b5R活性有抑制作用 ,抑制b5R活性从而抑制H2 O2

NADH-细胞色素b_5还原酶在甲状腺过氧化氢生物合成中的作用

目的 探讨 NADH-细胞色素 b5还原酶 (b5R)在甲状腺过氧化氢生物合成中作用。 方法 应用高香草酸荧光分析技术及 NADH-高铁氰化钾还原酶法 ,对正常和格雷夫斯病甲状腺过氧化氢 (H2 O2 )和 b5R进行测定 ,同时观察 b5R抑制剂对 H2 O2 生成和蛋白结合碘形成的影响。 结果 格雷夫斯病甲状腺 b5R活性和 H2 O2 水平均明显高于正常 ,而 H2 O2 酶活性在两者间差异无显著性。加 b5R抑制剂对氯汞苯甲酸抑制 b5R活性 ,格雷夫斯病和正常甲状腺 b5R活性降低近 85 % ,同时 H2 O2 降低近 5 0 % ,蛋白结合碘形成减少近 5 2 %。 b5R活性和 H2 O2 水平两者呈显著正相关。 结论 b5R参与甲状腺内 H2 O2 的生物合成 ,是甲状腺内产生 H2 O2 的重要酶系。

Characteristics and roles of cytochrome b5 in cytochrome P450-mediated oxidative reactions in Locusta migratoria

Cytochrome b5(Cyt-b5)is a small heme protein and known to be involved in a wide range of biochemical transformations,in eluding cytochrome P450 monooxyge nase(CYP)-mediated metabolism of endoge nous and exogenous compo un ds.Studies on Cyt-b5 are more con centrated in mammals,but are relatively rare in in sects.The characteristics and functi on of Cyt-b5 from Locusta migratoria have not been described yet.We sequeneed the full-length cDNA sequenee of Cyt-b5 from L.migratoria(LmCyt-b5)by reverse transcription-PCR(RT-PCR)based on locust transcriptome database.The phylogenetic analysis showed that LmCyt-b5 was closely related to the Cyt-b5 from Blattodea.LmCyt-b5 was highly expressed in ovary,Malpighian tubules,midgut,gastric caeca,and fat bodies.Silencing of LmCyt-b5 had no effect on the susceptibility of L.migratoria to four different insecticides.Suppression of LmCyt-b5 or silencing of both LmCyt-b5 and LmCPR did not significantly change the total CYP activity toward the substrate 7-ethoxycoumarin(7-EC).However,coexpression of LmCYP6FD1 with LmCPR and LmCyt-b5 together in Sf9 cells by using Bac-to-Bac baculovirus expression system significantly increased the catalytic activity of LmCYP6FD1 toward 7-EC as compared with the coexpression of L.mCYP6FD1 with cytochrome P450 reductase(LmCPR)or LmCyt-b5 separately.These results suggest that LmCyt-b5 plays an important role in the catalytic reaction of LmCYP6FD1 toward 7-EC in our in vitro experiments.Further study is needed to clarify the role of LmCyt-b5 in CYP-mediated catalytic reactions in L.migratoria.

腺苷脱氨酶、5′-核苷酸酶及谷胱甘肽还原酶联合检测在评估乙型肝炎患者肝损伤中的临床价值

[目的]探讨腺苷脱氨酶(ADA)、5′-核苷酸酶(5′-NT)及谷胱甘肽还原酶(GR)联合检测在评估乙型肝炎(CHB)患者肝损伤中的临床价值.[方法]选择2020年1月—2024年6月间就诊的72例CHB患者列入实验组,按照肝损伤不同程度分为轻度组(n=39)、中度组(n=25)、重度组(n=8),另选择同期健康体格检查的72例健康者列入对照组.采集所有研究对象血液样本,检测并比较各组血清ADA、5′-NT、GR水平.[结果]实验组血清ADA、5′-NT、GR水平均明显高于对照组(P<0.05);肝损伤重度组患者的血清ADA、5′-NT、GR水平明显高于中度组、轻度组,中度组血清ADA、5′-NT、GR水平明显高于轻度组,相比较差异均有统计学意义(P<0.05).[结论]血清ADA、5′-NT、GR联合检测可应用于CHB临床辅助诊断及肝损伤程度评估中,为临床诊断与治疗方案制定提供依据.

EB病毒转化的永生性人B淋巴母细胞中MTHFR基因的表达

为检测用 EB病毒转化建立的永生性人 B淋巴母细胞株中 N5 ,N1 0 -亚甲基四氢叶酸还原酶(MTHFR)基因的表达及其 c DNA序列 ,用 EB病毒转化人外周血 B淋巴细胞 ,建立永生性细胞株后 ,从培养细胞中提取总 RNA,用 RT- PCR法扩增 MTHFR基因 c DNA的不同片段 ,进行 PAGE电泳分析和 c DNA序列测定。结果显示永生性人 B淋巴母细胞中有 MTHFR基因表达 ,其 c DNA序列与文献报道的人肝脏MTHFR基因 c

New insights into the role of cytochrome P450 reductase (POR) in microsomal redox biology

Cytochrome P450 reductase(POR)is an essential electron transfer protein located on the endoplasmic reticulum of most cell types,and has long been appreciated for its role in cytochrome P450-mediated drug metabolism.Additional roles and electron acceptors for POR have been described,but it is largely with the recent availability of POR-null tissues that these supplemental roles for POR have been able to be explored.These studies have confirmed POR as the principal redox partner for the microsomal P450s responsible for drug and xenobiotic metabolism as well as cholesterol and bile acid synthesis,and for heme oxygenase,which catalyzes the initial step in the breakdown of heme.Surprisingly,these studies have revealed that squalene monooxygenase,an enzyme essential to cholesterol synthesis,has a second unknown redox partner in addition to POR,and that 7-dehydrocholesterol reductase,previously proposed to require POR as an electron donor,functions fully independently of POR.These studies have also helped define the role of cytochrome b5 in P450 catalysis,and raise the question as to the extent to which POR contributes to b5-dependent redox pathways.

Cytochrome b5 Reductase 1 Triggers Serial Reactions that Lead to Iron Uptake in Plants

Rhizosphere acidification is essential for iron （Fe） uptake into plant roots. Plasma membrane （PM） H＊-ATPases play key roles in rhizosphere acidification. However, it is not fully understood how PM H＋-ATPase activity is regulated to enhance root Fe uptake under Fe-deficient conditions. Here, we present evidence that cytochrome b5 reductase 1 （CBR1） increases the levels of unsaturated fatty acids, which stimulate PM H＋-ATPase activity and thus lead to rhizosphere acidification. CBRl-overexpressing （CBRI-OX） Arabidopsis thaliana plants had higher levels of unsaturated fatty acids （18：2 and 18：3）, higher PM H＊-ATPase activity, and lower rhizosphere pH than wild-type plants. By contrast, cbrl loss-of-function mutant plants showed lower levels of unsaturated fatty acids and lower PM H＊-ATPase activity but higher rhizosphere pH. Reduced PM H＊-ATPase activity in cbrl could be restored in vitro by addition of unsatu- rated fatty acids. Transcript levels of CBR1, fatty acids desaturase 2 （FAD2）, and fatty acids desaturase 3 （FAD3） were increased under Fe-deficient conditions. We propose that CBR1 has a crucial role in increasing the levels of unsaturated fatty acids, which activate the PM H＊-ATPase and thus reduce rhizosphere pH. This reaction cascade ultimately promotes root Fe uptake.

4-Hydroxycinnamic acid attenuates neuronal cell death by inducing expression of plasma membrane redox enzymes and improving mitochondrial functions

Many approaches to neurodegenerative diseases that focus on amyloid-βclearance and gene therapy have not been successful.Some therapeutic applications focus on enhancing neuronal cell survival during the pathogenesis of neurodegenerative diseases,including mitochondrial dysfunction.Plasma membrane(PM)redox enzymes are crucial in maintaining cellular physiology and redox homeostasis in response to mitochondrial dysfunction.Neurohormetic phytochemicals are known to induce the expression of detoxifying enzymes under stress conditions.In this study,mechanisms of neuroprotective effects of 4-hydroxycinnamic acid(HCA)were examined by analyzing cell survival,levels of abnormal proteins,and mitochondrial functions in two different neuronal cells.HCA protected two neuronal cells exhibited high expression of PM redox enzymes and the consequent increase in the NAD^(+)/NADH ratio.Cells cultured with HCA showed delayed apoptosis and decreased oxidative/nitrative damage accompanied by decreased ROS production in the mitochondria.HCA increased the mitochondrial complexes I and II activities and ATP production.Also,HCA increased mitochondrial fusion and decreased mitochondrial fission.Overall,HCA maintains redox homeostasis and energy metabolism under oxidative/metabolic stress conditions.These findings suggest that HCA could be a promising therapeutic approach for neurodegenerative diseases.

多功能氧化酶系(MFO)与棉铃虫抗药性关系初步研究

本文在增效作用测定基础上 ,研究比较了多功能氧化酶系 (MFO)的三个组分 (细胞色素 P4 50、细胞色素 b5、细胞色素 c还原酶 )在相对敏感棉铃虫 (HDS)与抗氰戊菊酯棉铃虫 (KQR)中的含量、活性及其组织分布规律。增效作用测定结果表明 ,PBO及 SV1对氰戊菊酯具有显著的增效作用 ,增效倍数分别达 2 53.99和71.4 4倍 ;初步表明 MFO在 KQR种群棉铃虫的抗药性中起着重要作用 ;随后的生化研究表明 :KQR种群棉铃虫中肠、脂肪体及体壁的三个组分含量均显著或极显著高于 HDS种群棉铃虫相应部位的含量 ,其中细胞色素 P4 50在上述三个部位中的含量分别是 HDS种群棉铃虫的 1.76、3.12、4 .15倍 ,细胞色素 b5含量分别是HDS种群棉铃虫的 1.57、6 .2 8、2 .39倍 ,细胞色素 c还原酶活性分别是 HDS种群棉铃虫的 1.4 0、1.88、1.6 4倍 。

遗传性高铁血红蛋白血症患者NADH-细胞色素b_5还原酶基因点突变的检测和基因诊断

为了探讨中国遗传性高铁血红蛋白血症患者的基因突变类型和建立相应的基因诊断方法，从已发现的１例Ⅰ型患者的外周血白细胞中提取ＲＮＡ，应用反转录ＰＣＲ法分析了Ｃｙｔｂ５ＲｃＤＮＡ的全部编码序列的９２１ｂｐ片段。结果显示：Ｃｙｔｂ５ＲｃＤＮＡ基因的第５７位密码子存在有Ａｒｇ→Ｇｌｎ（ＣＧＧ→ＣＡＧ）的错义突变。针对这一突变，用套式ＰＣＲ的方法对已有的３个家系共６名患者进行了基因诊断。结果表明其中两个家系的患者均有此位点的突变，５名患者３名为纯合子，２名为杂合子；而另一家系的患者未检测到，推测可能存在有其它突变类型。提示中国人遗传性高铁血红蛋白血症患者致病的分子基础，并建立了相应的基因诊断方法。