Oxidative modification of free-standing amino acids by Fe(Ⅱ)/αKG-dependent oxygenases

Fe(Ⅱ)/α-ketoglutarate(αKG)-dependent oxygenases catalyze the oxidative modification of various molecules,from DNA,RNA,and proteins to primary and secondary metabolites.They also catalyze a variety of biochemical reactions,including hydroxylation,halogenation,desaturation,epoxidation,cyclization,peroxidation,epimeriza-tion,and rearrangement.Given the versatile catalytic capability of such oxygenases,numerous studies have been conducted to characterize their functions and elucidate their structure-function relationships over the past few decades.Amino acids,particularly nonproteinogenic amino acids,are considered as important building blocks for chemical synthesis and components for natural product biosynthesis.In addition,the Fe(Ⅱ)/αKG-dependent oxy-genase superfamily includes important enzymes for generating amino acid derivatives,as they efficiently modify various free-standing amino acids.The recent discovery of new Fe(Ⅱ)/αKG-dependent oxygenases and the repur-posing of known enzymes in this superfamily have promoted the generation of useful amino acid derivatives.Therefore,this study will focus on the recent progress achieved from 2019 to 2022 to provide a clear view of the mechanism by which these enzymes have expanded the repertoire of free amino acid oxidative modifications.

Biochanin A attenuates spinal cord injury in rats during early stages by inhibiting oxidative stress and inflammasome activation

Previous studies have shown that Biochanin A,a flavonoid compound with estrogenic effects,can serve as a neuroprotective agent in the context of cerebral ischemia/reperfusion injury;howeve r,its effect on spinal cord injury is still unclea r. In this study,a rat model of spinal cord injury was established using the heavy o bject impact method,and the rats were then treated with Biochanin A(40 mg/kg) via intrape ritoneal injection for 14 consecutive days.The res ults showed that Biochanin A effectively alleviated spinal cord neuronal injury and spinal co rd tissue injury,reduced inflammation and oxidative stress in spinal cord neuro ns,and reduced apoptosis and pyroptosis.In addition,Biochanin A inhibited the expression of inflammasome-related proteins(ASC,NLRP3,and GSDMD)and the Toll-like receptor 4/nuclear factor-κB pathway,activated the Nrf2/heme oxygenase 1 signaling pathway,and increased the expression of the autophagy markers LC3 Ⅱ,Beclin-1,and P62.Moreove r,the therapeutic effects of Biochanin A on early post-s pinal cord injury were similar to those of methylprednisolone.These findings suggest that Biochanin A protected neurons in the injured spinal cord through the Toll-like receptor 4/nuclear factor κB and Nrf2/heme oxygenase 1 signaling pathways.These findings suggest that Biochanin A can alleviate post-spinal cord injury at an early stage.

Etomidate protects retinal ganglion cells from hydrogen peroxide-induced injury via Nrf2/HO-1 pathway

AIM:To determine whether etomidate(ET)has a protective effect on retinal ganglion cells(RGCs)injured with hydrogen peroxide(H_(2)O_(2))and to explore the potential mechanism underlying the antioxidative stress effect of ET.METHODS:Cultured RGCs were identified by double immunofluorescent labeling of microtubule-associated protein 2 and Thy1.1.An injury model of H_(2)O_(2)-induced RGCs oxidative stress was established in vitro.Cells were pretreated with different concentrations of ET(1,5,and 10μmol/L)for 4h,followed by further exposure to H_(2)O_(2)at 1000μmol/L.Cell counting kit 8 and Annexin V/propidium iodide assays were applied to detect the viabilities and apoptosis rates of the RGCs at 12,24,and 48h after H_(2)O_(2)stimulation.The levels of nitric oxide,malondialdehyde,and glutathione in culture media were measured at these time points.Quantitative reverse transcription polymerase chain reaction(qRT-PCR)and Western blot were performed to observe the effects of ET on the messenger RNA and protein expression of inducible nitric oxide synthase(iNOS),nuclear factor erythroid 2-related factor 2(Nrf2),heme oxygenase 1(HO-1),glutathione peroxidase 1 and the level of conjugated acrolein in RGCs at 12,24,and 48h after H_(2)O_(2)stimulation and in the retina at 12h after optic nerve transection(ONT).RESULTS:The applications of 5 and 10μmol/L of ET significantly increased the viability of RGCs.Results from qRT-PCR indicated a decrease in the expression of iNOS and an increase in the expressions of Nrf2 and HO-1 in ETpretreated RGCs at 12,24 and 48h after H_(2)O_(2)stimulation,as well as in ET-treated retinas at 12h after ONT.Western blot analysis revealed a decrease in the expression of iNOS and levels of conjugated acrolein,along with an increase in the expressions of Nrf2 and HO-1 in ET-pretreated RGCs in vitro and ET-treated retinas in vivo.CONCLUSION:ET is a neuroprotective agent in primary cultured RGCs injured by H_(2)O_(2).The effect of ET is dosedependent with the greatest effect being at 10μmol/L.ET plays an antioxidant role by inhibiting iNOS,up-regulating Nrf2/HO-1,decreasing the production of acrolein,and increasing the scavenge of acrolein.

Dual prognostic role of 2-oxoglutarate-dependent oxygenases in ten cancer types:implications for cell cycle regulation and cell adhesion maintenance

Background: Tumor hypoxia is associated with metastasis and resistance to chemotherapy and radiotherapy. Genes involved in oxygen-sensing are clinically relevant and have significant implications for prognosis. In this study, we examined the pan-cancer prognostic significance of oxygen-sensing genes from the 2-oxoglutarate-dependent oxygenase family. Methods: A multi-cohort, retrospective study of transcriptional profiles of 20,752 samples of 25 types of cancer was performed to identify pan-cancer prognostic signatures of 2-oxoglutarate-dependent oxygenase gene family (a family of oxygen-dependent enzymes consisting of 61 genes). We defined minimal prognostic gene sets using three independent pancreatic cancer cohorts (n = 681). We identified two signatures, each consisting of 5 genes. The ability of the signa-tures in predicting survival was tested using Cox regression and receiver operating characteristic (ROC) curve analyses. Results: Signature 1 (KDM8, KDM6B, P4HTM, ALKBH4, ALKBH7) and signature 2 (KDM3A, P4HA1, ASPH, PLOD1, PLOD2) were associated with good and poor prognosis. Signature 1 was prognostic in 8 cohorts representing 6 cancer types (n = 2627): bladder urothelial carcinoma (P = 0.039), renal papillary cell carcinoma (P = 0.013), liver cancer (P = 0.033 and P = 0.025), lung adenocarcinoma (P = 0.014), pancreatic adenocarcinoma (P < 0.001 and P = 0.040), and uterine corpus endometrial carcinoma (P < 0.001). Signature 2 was prognostic in 12 cohorts representing 9 cancer types (n = 4134): bladder urothelial carcinoma (P = 0.039), cervical squamous cell carcinoma and endocervical adenocar-cinoma (P = 0.035), head and neck squamous cell carcinoma (P = 0.038), renal clear cell carcinoma (P = 0.012), renal papillary cell carcinoma (P = 0.002), liver cancer (P < 0.001, P < 0.001), lung adenocarcinoma (P = 0.011), pancreatic adenocarcinoma (P = 0.002, P = 0.018, P < 0.001), and gastric adenocarcinoma (P = 0.004). Multivariate Cox regression confirmed independent clinical relevance of the signatures in these cancers. ROC curve analyses confirmed superior performance of the signatures to current tumor staging benchmarks. KDM8 was a potential tumor suppressor down- regulated in liver and pancreatic cancers and an independent prognostic factor. KDM8 expression was negatively correlated with that of cell cycle regulators. Low KDM8 expression in tumors was associated with loss of cell adhesion phenotype through HNF4A signaling. Conclusion: Two pan-cancer prognostic signatures of oxygen-sensing genes were identified. These genes can be used for risk stratification in ten diverse cancer types to reveal aggressive tumor subtypes.

Structural insights into the catalytic mechanism of aldehyde-deformylating oxygenases

The fatty alk（a/e）ne biosynthesis pathway found in cyanobacteria gained tremendous attention in recent years as a promising alternative approach for biofuel production. Cyanobacterial aldehyde-deformylating oxygenase （cADO）, which catalyzes the conversion of Cn fatty aldehyde to its corresponding Cn-1 alk（ale）ne, is a key enzyme in that pathway. Due to its low activity, alk（a/e）ne production by cADO is an inefficient process. Previous biochemical and structural investi. gations of cADO have provided some information on its catalytic reaction. However, the details of its cata- lytic processes remain unclear. Here we report five crystal structures of cADO from the Synechococcus elongates strain PCC7942 in both its iron-free and iron-bound forms, representing different states during its catalytic process. Structural comparisons and functional enzyme assays indicate that Giu144, one of the iron-coordinating residues, plays a vital role in the catalytic reaction of cADO. Moreover, the helix where Glu144 resides exhibits two distinct conformations that correlates with the different binding states of the di-iron center in cADO structures. Therefore, our results provide a structural explanation for the highly labile feature of cADO di-iron center, which we pro- posed to be related to its low enzymatic activity. On the basis of our structural and biochemical data, a possible catalytic process of cADO was proposed, which could aid the design of cADO with improved activity.

The functional differentiation of the post-PKS tailoring oxygenases contributed to the chemical diversities of atypical angucyclines

Angucyclines are one of the largest families of aromatic polyketides with various chemical structures and bioactivities.Decades of studies have made it easy for us to depict the picture of their early biosynthetic pathways.Two families of oxygenases,the FAD-dependent oxygenases and the ring opening oxygenases,contribute to the formation of some unique skeletons of atypical angucyclines.The FAD-dependent oxygenases involved in the biosynthetic gene clusters of typical angucyclines catalyze two hydroxylation reactions at C-12 and C-12b of prejadomycin,while their homolog JadH in jadomycin gene cluster catalyze the C-12 hydroxylation and 4a,12b-dehydration reactions of prejadomycin,which leads to the production of dehydrorabelomycin,a common intermediate during the biosynthesis of atypical angucyclines.Ring opening oxygenases of a unique family of oxygenases catalyze the oxidative CeC bond cleavage reaction of dehydrorabelomycin,followed by different rearrangement reactions,resulting in the formation of the various chemical skeletons of atypical angucyclines.These results suggested that the functional differentiation of these oxygenases could apparently enrich the sources of aromatic polyketides with greater structure diversities.

Upregulation of CDGSH iron sulfur domain 2 attenuates cerebral ischemia/reperfusion injury

CDGSH iron sulfur domain 2 can inhibit ferroptosis,which has been associated with cerebral ischemia/reperfusion,in individuals with head and neck cancer.Therefore,CDGSH iron sulfur domain 2 may be implicated in cerebral ischemia/reperfusion injury.To validate this hypothesis in the present study,we established mouse models of occlusion of the middle cerebral artery and HT22 cell models of oxygen-glucose deprivation and reoxygenation to mimic cerebral ischemia/reperfusion injury in vivo and in vitro,respectively.We found remarkably decreased CDGSH iron sulfur domain 2 expression in the mouse brain tissue and HT22 cells.When we used adeno-associated virus and plasmid to up-regulate CDGSH iron sulfur domain 2 expression in the brain tissue and HT22 cell models separately,mouse neurological dysfunction was greatly improved;the cerebral infarct volume was reduced;the survival rate of HT22 cells was increased;HT22 cell injury was alleviated;the expression of ferroptosis-related glutathione peroxidase 4,cystine-glutamate antiporter,and glutathione was increased;the levels of malondialdehyde,iron ions,and the expression of transferrin receptor 1 were decreased;and the expression of nuclear-factor E2-related factor 2/heme oxygenase 1 was increased.Inhibition of CDGSH iron sulfur domain 2 upregulation via the nuclear-factor E2-related factor 2 inhibitor ML385 in oxygen-glucose deprived and reoxygenated HT22 cells blocked the neuroprotective effects of CDGSH iron sulfur domain 2 up-regulation and the activation of the nuclear-factor E2-related factor 2/heme oxygenase 1 pathway.Our data indicate that the up-regulation of CDGSH iron sulfur domain 2 can attenuate cerebral ischemia/reperfusion injury,thus providing theoretical support from the perspectives of cytology and experimental zoology for the use of this protein as a therapeutic target in patients with cerebral ischemia/reperfusion injury.

Cytoprotective role of heme oxygenase-1 and heme degradation derived end products in liver injury

The activation of heme oxygenase-1(HO-1) appears to be an endogenous defensive mechanism used by cells to reduce inflammation and tissue damage in a number of injury models. HO-1, a stress-responsive enzyme that catabolizes heme into carbon monoxide(CO), biliverdin and iron, has previously been shown to protect grafts from ischemia/reperfusion and rejection.In addition, the products of the HO-catalyzed reaction, particularly CO and biliverdin/bilirubin, have been shown to exert protective effects in the liver against a number of stimuli, as in chronic hepatitis C and in transplanted liver grafts. Furthermore, the induction of HO-1 expression can protect the liver against damage caused by a number of chemical compounds. More specifically, the CO derived from HO-1-mediated heme catabolism has been shown to be involved in the regulation of inflammation; furthermore, administration of low concentrations of exogenous CO has a protective effect against inflammation. Both murine and human HO-1 deficiencies have systemic manifestations associated with iron metabolism, such as hepatic overload(with signs of a chronic hepatitis) and iron deficiency anemia(with paradoxical increased levels of ferritin).Hypoxia induces HO-1 expression in multiple rodent,bovine and monkey cell lines, but interestingly, hypoxia represses expression of the human HO-1 gene in a variety of human cell types(endothelial cells, epithelial cells, T cells). These data suggest that HO-1 and CO are promising novel therapeutic molecules for patients with inflammatory diseases. In this review, we present what is currently known regarding the role of HO-1 in liver injuries and in particular, we focus on the implications of targeted induction of HO-1 as a potential therapeutic strategy to protect the liver against chemically induced injury.

环氧化酶-2在胃癌中的研究进展

环氧化酶（cyclooxygenase，COX）又称前列腺素内过氧化物合成酶，是前列腺素合成过程中一个主要的限速酶，可将花生四烯酸代谢成各种前列腺素产物．从而参与机体的多种病理生理过程。目前发现哺乳动物COX至少有两种同工酶，

Effects of Batroxobin on Spatial Learning and Memory Disorder of Rats with Temporal Ischemia and the Expression of HSP32 and HSP70

The effect of Batroxobin on spatial memory disorder of left temporal ischemic rats and the expression of HSP32 and HSP70 were investigated with Morri`s water maze and immunohistochemistry methods. The results showed that the mean reaction time and distance of temporal ischemic rats in searching a goal were significantly longer than those of the sham-operated rats and at the same time HSP32 and HSP70 expression of left temporal ischemic region in rats was significantly increased as compared with the sham-operated rats. However, the mean reaction time and distance of the Batroxobin-treated rats were shorter and they used normal strategies more often and earlier than those of ischemic rats. The number of HSP32 and HSP70 immune reactive cells of Batroxobin-treated rats was also less than that of the ischemic group. In conclusion, Batroxobin can improve spatial memory disorder of temporal ischemic rats; and the down-regulation of the expression of HSP32 and HSP70 is probably related to the attenuation of ischemic injury.

血红素氧合酶-1与缺血性脑血管病关系的临床研究

血红素氧合酶(heme oxygenase,HO)是血红素降解过程中的限速酶,迄今已发现HO有3种亚型:HO-1、HO-2和HO-3。HO-1能将具有氧化性质的血红素分解生成具有抗氧化性质的胆红素和抗炎症作用的CO,而发挥抗炎症与抗氧化应激等细胞保护功能[1]。作为发病与炎症和氧化应激密切相关的缺血性脑血管病,HO-1水平与其的关系目前国内外鲜有报道。本研究通过检测缺血性脑血管病患者及正常对照组血清HO-1水平,为进一步探索通过调节HO-1的表达用于临床提供理论依据。

血红素加氧酶-1在炎症性肠病中的研究进展

血红素加氧酶（heme oxygenase．HO）是血红素降解过程中的限速酶．可将血红素降解为等摩尔的胆绿素、游离铁和一氧化碳（CO）。近年研究发现HO-1具有抗炎、抗凋亡、抗增生效应。炎症性肠病（IBD）包括溃疡性结肠炎（UC）和克罗恩病（CD），其病因和发病机制尚未完全阐明。目前认为IBD主要系由免疫反应介导．并与遗传、环境因素密切相关。其特点之一是炎性细胞增多，炎性细胞因子表达增加。新近研究证实，HO-1的诱导表达对实验性结肠炎动物模型有重要保护作用，能减轻IBD由免疫系统活化所致的组织损伤，预示着HO-1在IBD的治疗中具有广泛应用前景。

血红素加氧酶1对心血管保护作用的研究新进展

心血管疾病在全世界发生率逐年增高，严重危害人类的健康。研究表明，动脉粥样硬化、移植后损伤、缺血再灌注损伤等许多血管性疾病的发生发展都和氧化应激密切相关。因此，体内一些抗氧化剂或应激蛋白表达的升高可能对心血管起着重要的保护作用。血红素加氧酶1（heme oxygenase，HO-1）是一种广泛参与体内抗氧化应激的可诱导酶。最近的多项研究证明，HO-1表达升高对心血管的保护具有积极的意义，并且HO-1的启动子的基因多态性与心血管疾病的发生密切相关。本文就近年来关于HO-1对心血管保护作用的研究最新进展加以综述，旨在为心血管疾病的基因治疗提供新的思路。

环加氧酶-2和血管内皮生长因子蛋白在卵巢上皮癌中的表达情况及生物学意义

卵巢上皮癌是临床妇科常见的恶性肿瘤,大多数患者确诊时已属于中晚期。研究证实肿瘤的发生、发展受多种细胞基因及细胞因子的调控。环加氧酶（cyclo-oxygenase,COX）是花生四烯酸转化为前列腺素一种重要的限速酶,存在结构型COX-1和诱生型COX-2两种亚型,其中COX-2是诱导型酶,