Role of succinate dehydrogenase deficiency and oncometabolites in gastrointestinal stromal tumors

Gastrointestinal stromal tumors(GISTs)are the most common mesenchymal tumors of the gastrointestinal tract.At the molecular level,GISTs can be categorized into two groups based on the causative oncogenic mutations.Approximately 85%of GISTs are caused by gain-of-function mutations in the tyrosine kinase receptor KIT or platelet-derived growth factor receptor alpha(PDGFRA).The remaining GISTs,referred to as wild-type(WT)GISTs,are often deficient in succinate dehydrogenase complex(SDH),a key metabolic enzyme complex in the tricarboxylic acid(TCA)cycle and electron transport chain.SDH deficiency leads to the accumulation of succinate,a metabolite produced by the TCA cycle.Succinate inhibitsα-ketoglutarate-dependent dioxygenase family enzymes,which comprise approximately 60 members and regulate key aspects of tumorigenesis such as DNA and histone demethylation,hypoxia responses,and m6A mRNA modification.For this reason,succinate and metabolites with similar structures,such as D-2-hydroxyglutarate and fumarate,are considered oncometabolites.In this article,we review recent advances in the understanding of how metabolic enzyme mutations and oncometabolites drive human cancer with an emphasis on SDH mutations and succinate in WT GISTs.

Molecular Weight of Cytoplasmic Malate Dehydrogenase,Mitochondrial Malate Dehydrogenase and Lactate Dehydrogenase of a Freshwater Catfish

The multiple molecular forms of cytoplasmic malate dehydrogenase (cMDH), mitochondrial malate dehydrogenase (mMDH ) and lactate dehydrogenase (LDH ) were studied in the liver and skeletal muscle of the freshwater catfish, Clarias batrachus. There were two electrophoretically distinguishable bands (AA andBB) of cMDH and mMDH which suggests that they are apparently encoded at two gene loci (A and B) in both the tissues.However, the presence of a single band (LDH-1 ) of LDH in liver and double bands (LDH-1and LDH-2) in skeletal muscle in which LDH-2 was predominant reflects the differential expression of LDH genes in different metabolic tissues to meet the requirement of energy production. The AA isoform (74 kd) of liver cMDH was smaller than those of the AA form (110 kd) of skeletal muscle. In contrast, the BB isoform of liver (42 kd) and skeletal muscle (54 kd) were more or less similar in size. Unlike the case of cMDH, the molecular weight of AA isoform (115 kd) of liver mMDH was higher than those of the AA form (87kd) of skeletal muscle. Whereas the molecular weight of BB isoform (58 kd) of liver was in proximity to the weight of BB form (44 kd) of skeletal muscle mMDH. The size of AA isoform (74 kd) of liver cMDH was smaller, while the AA isoform (110 kd) of skeletal muscle was larger as compared to AA form of mMDH in the liver (115 kd) and skeletal muscle (87 kd). But the size of BB isoform of both the isozymes was almost equal in these metabolic tissues. The molecular weight of liver LDH-1 (96 kd) was close to the weight of LDH-1 (82 kd) in skeletal muscle. The molecular weight of skeletal muscle LDH-2 was deduced as 37 kd which is much more lower than the weight of LDH-1 in liver and skeletal muscle. The smaller size of LDH-2 in skeletal muscle may be of a physiological significance in this anaerobic tissue

Effect of Nitric Oxide on the Interaction Between Mitochondrial Malate Dehydrogenase and Citrate Synthase

Mitochondrial malate dehydrogenase （mMDH） and citrate synthase （CS） are sequential enzymes in Krebs cycle. mMDH, CS and the complex between mMDH and CS （mMDH＋CS） were treated with nitric oxide solution. The roles of notric oxide （NO） on the secondary structures and the interactions between mMDH and CS were studied using circular diehroism （CD） and Fourier transform surface plasmon resonance （FT-SPR）, respectivley. The effects of NO on the activities of mMDH, CS and mMDH＋CS were also studied. And the regulations by NO on mMDH and CS were simulated by PyMOL software. The results of SPR conifrmed that strong interaction between mMDH and CS existed and NO could signiifcantly regulate the interaction between the two enzymes. NO reduced the mass percents ofα-helix and increased that of random in mMDH, CS and mMDH＋CS. NO increased the activities of CS and mMDH＋CS, and inhibited the activity of mMDH. Graphic simulation indicated that covalent bond was formed between NO and Asn242 in active site of CS. However, there was no direct bond between NO and mMDH. The increase in activity of mMDH＋CS complex depended mostly on the interaction between NO and CS. All the results suggested that the regulations by NO on the activity and interaction between mMDH and CS were accord with the changes in mMDH, CS and mMDH＋CS caused by NO.

Tear Malate Dehydrogenase,Lactate Dehydrogenase and Their Isoenzymes in Normal Chinese Subjects and Patients of Ocular Surface Disorders

Purose:To determine levels of malate dehydrogenase(MDH),lactate dehydroge-nase(LDH)and their isoenzymes in tears of normal Chinese subjects and patients with ocular surface disorders.Methods:The age range of normal subjects was10-88,with136mal and 128fe-male subjects.123patients suffered from ocular surface disorders.Tears were col-lected from lower fornix on Xinghua filter disc(0.1mm thick,5mm in diameter).The values of tearMDHand LDHwere determined by MONARCH-2000Ana-lyzer(U.S.A)Their isoenzymes were separated by acetate cellulose elec-trophoresis and were determined by Model CDS-200light densitometer.Results:The normal values of tear LDH and MDH were 45.51+23.00-81.35+37.84umol·s^-1/Land11.00+5.33-19.50+9.17umol·s^-1/Lrespectively,dis-regarding sex or eye distriction(P>0.05).The values of tear LDHandMDH in the group aged10-19were significantly lower than in another groups(P<0.05),95%normal ranges of tearMDHaged below19and above20were3.63-19.90umol·s^-1/L.THe MDH isoenzymes comprised MDHs and MDHm,the former accounting for80.0-89.1%.The LDH isoenzymes comprised 5varieties.of which the ratioH/Mof subunit H tosubunit Mwas0.196+0.02.Levels of tear LDH,MDHand their isoenzymes in different diseases were various.Conclusions;Tear LDH/MDHratio reflected sensitively the matabolism of corneae and conjunetival epithelium.The changes in LDH isoenzymes were hel-ful to the differential diagnosis of external eye diseases,and the increase of MDHm reflected sensitively the degree of injury to the corneal epithelium.

Evaluation of Tear Malate Dehydrogenase 2 in Mild Dry Eye Disease

Purpose: To evaluate the effect of tear malate dehydrogenase2 on monitoring ocular surface injury in mild dry eye(DE)disease.Methods: A total of 15 DE patients(30 eyes) with mild subjective symptoms but no ocular surface fluorescein staining signs were enrolled in this study.(DE group)..The control group was 15 healthy age- and sex-matched volunteers(30eyes)..All subjects were asked to fill out a DE symptoms questionnaire and take different tests including tear MDH and MDH2 activities evaluation,..tear breakup time.(TBUT),Schirmer I,.and slit-lamp examination of the ocular surface.We investigated different changes in tear MDH and MDH2 activities in the DE group and control group,.discussed the association between tear MDH2 activity and DE symptoms, and the relationship between tear MDH2 activity and diagnostic tests(Schirmer I and TBUT). We also analyzed the changes in tear MDH2 activities after the treatment with artificial tears.Results:.Tear MDH activities in the DE group and control group were 288 ±102 U / L and 259 ±112 U / L,.respectively,and this difference was not statistically significant(P >0.05).The tear MDH2 activities in DE group were significantly increased compared with control group. Tear MDH2 was significantly and negatively correlated with the Schirmer's value(r=-0.733,P<0.01) and the TBUT value(r=-0.841,P<0.01)..MDH2 also had a significant positive correlation with soreness symptoms(r=0.687, P < 0.01). Treatment with artificial tears relieved or eliminated all discomfort symptoms, together with a considerable decrease in MDH2 activities(P <0.01),.but no significant changes in the Schirmer and the TBUT tests were observed.Conclusion: Tear MDH2 activity can indicate ocular surfaceinjury in mild DE patients and may be used to monitor the response to therapy.

Duplication of Locus Coding of Malate Dehydrogenase in Populus tomentosa Carr

Horizontal starch-gel electrophoresis was used to study crude enzyme extraction from young leaves of 234 clones of Populus tomentosa Cart. selected from nine provenances in North China. Ten enzyme systems were resolved. One hundred and fifty-six clones showing unusual allozyme band patterns at locus Mdh-Ⅰ were found. Three allozyme bands at locus Mdh-Ⅰ were 9：6：1 in concentration. Further studies on the electrophoretic patterns of ground mixed pollen extraction of 30 male clones selected at random from the 156 clones were conducted and it was found that allozyme bands at locus Mdh-Ⅰ were composed of two dark-stained bands and a weak band. Only one group of the malate dehydrogenase （MDH） zymogram composed of two bands was obtained from the electrophoretic segregation of pollen leachate of the same clones. A comparison of the electrophoretic patterns one another suggested that the locus Mdh-Ⅰ coding malate dehydrogenase in diploid species of P. tomentosa was duplicated. The duplicate gene locus possessed three same alleles and was located in mitochondria. The locus duplication of alleles coding malate dehydrogenase in P.tomentosa was discovered and reported for the first time.

A NOVEL Ser73Gly VARIATION OF SUCCINATE DEHYDROGENASE,SUBUNIT D AND A Cys634Gly MUTATION IN Ret PROTO-ONCOGENE OBSERVED IN A CHINESE MULTIPLE ENDOCRINE NEOPLASIA TYPE 2A PATIENT

Multiple endocrine neoplasia type 2A(MEN2A)is an autosomal dominant cancer syndrome that is characterized by medullary thyroid carcinoma(MTC),pheochromocytoma(50%-60% of cases),and hyperplasia of the parathyroid glands(20%-30% of cases).MEN2A comprises a heterogeneous group of neoplastic disorders that most commonly have a single missense substitution of the Ret proto-oncogene(RET)involving exons 10 and 11.Here,we reported a novel case of MEN2A associated with two variations in two distinct genes,Cys634Gly in RET and a rare Ser73Gly substitution in succinate dehydrogenase,subunit D(SDHD).Because the patient presented with medullary thyroid carcinoma and pheochromocytoma but without parathyroid gland involvement,we speculated that this clinical feature could be correlated with the two substitutions.This is the first report of a MEN2A case involving two different changes one in the RET gene and the other in the SDHD gene.

Death mode-dependent reduction in succinate dehydrogenase activity in hair cells of aging rat cochleae

Background Our previous studies have shown that both apoptosis and necrosis are involved in hair cell （HC） pathogenesis in aging cochleae. To better understand the biological mechanisms responsible for the regulation of HC death, we examined the activity of succinate dehydregenase （SDH）, a mitochondrial bioenergetic enzyme, in the HCs of aging cochleae. Methods The auditory brainstem response thresholds elicited by tone bursts at 4, 10 and 20 kHz were measured in both young （2-3 months） and aging （22-23 months） Wistar rats. SDH activity was evaluated with a colorimetric assay using nitroblue tetrazolium monosodium salt. The SDH-labeled organs of Corti were double stained with propidium iodide, a DNA intercalating fluorescent probe for illustration of HC nuclei. All the specimens were examined with fluorescence microscopy and confocal microscopy. Results Aging rats exhibited a significant elevation of ABR thresholds with threshold shifts being 34 dB at 20 kHz, 28 dB at 10 kHz, and 25 dB at 4 kHz. Consistent with the reduction in the cochlear function, aging cochleae exhibited the reduction of SDH staining intensity in the apical and the basal ends of the cochleae, where a large number of apoptotic, necrotic, and missing HCs were evident. The reduction in SDH staining appeared in a cell-death-mode dependent fashion. Specifically, SDH labeling remained in apoptotic HCs. In contrast, SDH staining was markedly reduced or absent in necrotic HCs. Conclusions In the aging cochlea, SDH activity is preserved in HCs undergoing apoptosis, but is substantially reduced in necrosis. These results sUggest that mitochondrial energetic function is involved in the regulation of cell death pathways in the pathogenesis of aging cochleae.

Succinate dehydrogenase in Parkinson＇s disease

BACKGROUND： The prevalence of neurodegenerative disorders such as Parkinson＇s disease （PD） is increased by age. Alleviation of their symptoms and protection of normal neurons against degeneration are the main aspects of the researches to establish novel therapeutic strategies. Many studies have shown that mitochondria as the most important organelles in the brain which show impairment in PD models. Succinate dehydrogenase （SDH） as a component of the oxidative phosphorylation system in mitochondria connects Krebs cycle to the electron transport chain. Dysfunction or inhibition of the SDH can trigger mitochondrial impairment and disruption in ATP generation. Excessive in lipid synthesis and induction of the excitotoxicity as inducers in PD are controlled by SDH activity directly and indirectly. On the other hand, mutation in subunits of the SDH correlates with the onset of neurodegenerative disorders. Therefore, SDH could behave as one of the main regulators in neuroprotection. OBJECTIVE： In this review we will consider contribution of the SDH and its related mechanisms in PD. METHODS： Pubmed search engine was used to find published studies from 1977 to 2016. ＂Succinate dehydrogenase＂, ＂lipid and brain＂, ＂mitochondria and Parkinson＇s disease＂ were the main keywords for searching in the engine. RESULTS： Wide ranges of studies （59 articles） in neurodegenerative disorders especially Parkinson＇s disease like genetics of the Parkinson＇s disease, effects of the mutant SDH on cell activity and physiology and lipid alteration in neurodegenerative disorders have been used in this review. CONCLUSION： Mitochondria as key organelles in the energy generation plays crucial roles in PD. ETC complex in this organelle consists four complexes which alteration in their activities cause ROS generation and ATP depletion. Most of complexes are encoded by mtDNA while complex Ⅱ is the only part of the ETC which is encoded by nuclear genome. So, focusing on the SDH and related pathways which have important role in neuronal survival and SDH has a potential to further studies as a novel neuroproteetive agent.

Molecular Characterization of a Cytosolic Malate Dehydrogenase Gene（GhcMDH1） from Cotton

Malate dehydrogenase（MDH） is a key enzyme that catalyzes the reversible oxidation of oxaloacetate to malate and plays an important role in the physiological processes of plant growth and development. However, cyto- solic malate dehydrogenase（cMDH）, which is crucial for malate synthesis in the cytosol, still has not been extensively characterized in plants. Here, we isolated a cytosolic malate dehydrogenase gene, designated as GhcMDH1, from Gossypium hirsutum and characterized its possible molecular function in cotton fiber. The cloned cDNA of GhcMDH1 is 1520 base pairs in length, and has an open reading frame of 999 base pairs, encoding for 332 amino acid residues with an estimated molecular weight of 35580 and pI of 6.35. Sequence alignment showed that the de- duced amino acid sequence of GhcMDH1 protein shared a high similarity to other plant cMDHs. Confocal and im- munological analysis confirmed that GhcMDH1 protein was subcellularly localized to the cytosol. Quantitative real-time polymerase chain reaction（PCR） revealed that GhcMDH1 was constitutively expressed in all vegetative cotton tissues, with slightly lower levels in roots than stems and leaves. Interestingly, the transcripts of GhcMDH1 were detected in 5--25 d post anthesis（DPA） fibers and highly abundant at 15 DPA fibers. The total MDH activities and malate contents of cotton fibers were positively correlated with the fiber elongation rates, suggesting that GhcMDH1 may function in malate synthesis in fast fiber elongation. In agreement with this suspicion, the recombi- nant His-GhcMDH1 protein mainly drives the reaction towards malate generation in vitro. In conclusion, our mole- cular characterization of the GhcMDH1 gene provides valuable insights to further investigate the malate equilibrium in cotton fiber development.

Cloning, expression and protective immunity evalua-tion of the full-length cDNA encoding succinate dehydrogenase iron-sulfur protein of Schistosoma japonicum

1071-bp fragment was obtained from the Schistosoma japonicum (Chinese strain) adult cDNA library after the 3′ and 5′ ends of the incomplete expression sequence tag (EST) of succinate dehydrogenase iron-sulfur protein of Schistosoma japonicum (SjSDISP) were amplified by the anchored PCR with 2 pairs of primers designed according to the EST of SjSDISP and the sequence of multiclone sites of the library vector. Sequence analysis indicated that the fragment was a full-length cDNA with a complete open reading frame (ORF), encoding 278 amino acid residues. The fragment was cloned into prokary- otic expression vector pQE30, and subsequently sequenced and expressed in Escherichia coli. SDS-PAGE and Western-blot analyses showed that the recombinant protein was about 32 kD and could be recognized by the polyclonal antisera from rabbits immunized with Schistosoma japonicum adult worm antigen. Compared with the FCA controls, mice vaccinated with rSjSDISP (test) or rSjGST (posi- tive control) all revealed high levels of specific antibody and significant reduction in worm burden, liver eggs per gram (LEPG), fecal eggs per gram (FEPG) and intrauterine eggs. These results suggest that SjSDISP may be a novel and partially protective vaccine candidate against schistosomiasis. In contrast to the worm burden reduction rate, the higher degree of egg reduction rate in the test group also sug- gested that SjSDISP vaccine may primarily play a role in anti-embryonation or anti-fecundity immunity.

Malate and Lactate Dehydrogenases of a Freshwater Catfish: Impact of Endosulfan

A sublethal concentration of technical grade endosulfan (END) inhibited 35 to 55% of the activities of cytoplasmic malate dehydrogenase (cMDH), mitochondrial malate dehydrogenase (mMDH), and lactate dehydrogenase (LDH) in the liver and the skeletal muscle of a freshwater catfish, Clarias halrachus, after 7 days of exposure. The activity remained in the inhibited state up to 28 days. The withdrawal of END from the medium after 1 week of exposure gradually restored the activities to control levels within 21 days in the skeletal muscle and 28 days in the liver. The administration of actinomycin D or cycloheximide between the 14th and the 21st day of the withdrawal of END almost completely inhibited the withdrawal-dependent recovery in the activities of all the three enzymes. This indicates de novo synthesis of the enzymes during the recovery period. A conjoint treatment of END and triiodothyronine (T_3) raised the activities of cMDH, mMDH, and LDH in the liver and the skeletal muscle up to the control levels. This shows that the inhibitory effect of END may be relieved in presence of T_3. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed few changes in the pattern of cytoplasmic proteins of the liver and the skeletal muscle in response to exposure to END. 1990 Academic Press. Inc.

A Review on Molecular Physiology of Malate and Lactate Dehydrogenases in Fishes

The malate(EC 1.1.1.37)and lactate(EC 1.1.1.27)dehydrogenases are themetabolic enzymes directly or indirectly involved in energy production,gluconeogenesis and lipogenesis.Malate dehydrogenase(MDH)exists in twoisoenzymic forms,cytoplasmic(cMDH)and mitochondrial(mMDH),composed of Aand/or B subunits(dimeric molecule:MW 40,000-120,000).Lactate dehydrogenase(LDH)has tetrameric(MW 35,000-110,000)structure made up of either A and/or B,orC(C,E,F)subunits.They catalyze an ordered bisubstrate(substrate and coenzyme)

Human lactate dehydrogenase and malate dehydrogenase possess the catalytic properties to produce aromaticα‑hydroxy acid

Lactate dehydrogenase and malate dehydrogenase are the two main alpha-hydroxy acid dehydrogenases in the human body.We investigated the catalytic properties of human lactate dehydrogenase LDHC,LDHL6A and malate dehydrogenase MDH1 on aromaticα-keto acids phenylpyruvic acid,p-hydroxyphenylpyruvic acid and 3,4-dihydroxyphenylpyruvic acid.The optimum temperatures for LDHC,LDHL6A,and MDH1 are 37℃,35℃,and 45℃,respectively;and the optimum pH is 6.5,6.5,and 5.5,respectively.The K_(m)of LDHC for phenylpyruvic acid and 3,4-dihydroxyphenylpyruvic acid were 0.90 mM and 0.92 mM,respectively.LDHL6A has a high affinity for phenylpyruvic acid and 3,4-dihydroxyphenylpyruvic acid with K_(m)of 0.77 mM and 0.80 mM,respectively;MDH1 has an extremely high affinity(K_(m)=0.46 mM)and catalytic efficiency(k_(cat)/K_(m)=23.87 s^(-1)·mM^(-1))for p-hydroxyphenylpyruvic acid.It also has a high affinity for 3,4-dihydroxyphenylpyruvic acid with a K_(m)of 0.90 mM,but with a low affinity for phenylpyruvic acid(K_(m)=3.76 mM).The catalytic properties of human LDHC,LDHL6A,and MDH1 for the abovementioned aromaticα-keto acids may be one of the sources of L-phenyllactic acid,L-p-hydroxyphenyllactic acid,and L-3,4-dihydroxyphenyllactic acid in humans.

高盐饮食导致小鼠卵巢组织线粒体功能异常

目的分析高盐饮食对卵巢线粒体功能的影响。方法将20只雌性ICR小鼠随机分为正常盐饮食(NSD)组和高盐饮食(HSD)组,每组10只。NSD组给予正常盐饮食,HSD组给予8%NaCl高盐饮食,持续4周。通过NaCl诱导体外培养的人卵巢颗粒细胞COV-434建立高盐处理细胞模型。采用Western blotting检测超氧化物歧化酶(SOD)和电子传递链复合物(Complex)Ⅰ~Ⅴ的表达情况,动力学法检测SOD和琥珀酸脱氢酶(SDH)的活性,化学发光法检测ATP水平。结果与NSD组相比,HSD组小鼠卵巢ComplexⅠ表达水平显著下降(P<0.01),ComplexⅤ表达水平显著升高(P<0.05),SDH活性显著降低(P<0.01),血清和卵巢中ATP含量也显著下降(P<0.01)。高盐处理后COV-434细胞中ComplexⅠ和ComplexⅡ表达水平显著下降(P<0.05),ComplexⅤ表达水平显著升高(P<0.05),SDH活性显著降低(P<0.01),ATP含量不足(P<0.01)。结论高盐可引起小鼠卵巢线粒体的氧化稳态失衡、Complex表达水平变化、三羧酸循受阻以及ATP水平不足等线粒体功能障碍。

琥珀酸脱氢酶A对胃癌增殖、迁移和侵袭的影响及意义

目的检测琥珀酸脱氢酶A(SDHA)在胃癌组织及细胞中的表达水平,探讨其对胃癌增殖、迁移和侵袭能力的影响。方法通过免疫组织化学法检测SDHA在胃癌组织及癌旁组织中的表达情况。结合Western blotting检测SDHA在正常胃上皮细胞与胃癌细胞中的表达。通过Transwell实验、划痕实验、CCK-8实验、克隆形成实验进一步研究异常表达SDHA对胃癌细胞迁移、侵袭和增殖能力的影响。结果免疫组织化学及Western blotting结果提示,SDHA在胃癌组织及胃癌细胞中高表达。敲低及过表达SDHA可影响胃癌细胞的增殖、迁移和侵袭。此外,SDHA表达与肿瘤免疫浸润显著相关。结论SDHA能够促进胃癌细胞增殖、迁移和侵袭,有望成为胃癌治疗的潜在靶点。

琥珀酸/GPR91通过DHODH/CoQ10促血管内皮细胞线粒体损伤

[目的]探讨琥珀酸/G蛋白偶联受体91(GPR91)对血管内皮细胞线粒体的影响及其调节机制。[方法]采用透射电镜、Western blot、荧光显微镜观察琥珀酸类似物琥珀酸二乙酯(DS)、GPR91激动剂及抑制剂对血管内皮细胞线粒体形态、嵴、嵴稳态相关蛋白、活性氧(ROS)含量、Ca^(2+)浓度、膜电位、二氢乳清酸脱氢酶(DHODH)表达以及氧化型辅酶Q10(CoQ10)的影响;荧光探针法观察DHODH抑制剂以及氧化型CoQ10对血管内皮细胞ROS含量、Ca^(2+)浓度的影响。[结果]DS处理后,血管内皮细胞线粒体固缩、体积变小、双层膜电子密度增加、嵴数量减少,嵴稳态相关蛋白MIC60表达下调23%,ROS含量升高,Ca^(2+)浓度增加,线粒体膜电位降低(P<0.05或P<0.01);GPR91激动剂处理后,线粒体嵴稳态相关蛋白MIC60表达下调31%,ROS含量升高27%,钙离子浓度升高36%,线粒体膜电位降低(P<0.05或P<0.01);GPR91抑制剂处理后,线粒体嵴稳态相关蛋白MIC60上调22%,ATP5I上调40%,ROS含量降低41%,Ca^(2+)浓度降低67%,线粒体膜电位恢复正常(P<0.05或P<0.01)。DS处理后,DHODH的表达下调43%,氧化型CoQ10的含量增加120%(P<0.05或P<0.01);GPR91激动剂处理后,DHODH的表达下调22%,氧化型CoQ10的含量增加36%(P<0.05或P<0.01);GPR91抑制剂处理后,DHODH的表达上调40%,氧化型CoQ10的含量降低39%(P<0.01);DHODH抑制剂处理后,ROS含量增加20%,Ca^(2+)浓度增加28%,线粒体膜电位降低(P<0.05或P<0.01);外源加入氧化型CoQ10处理后,ROS含量降低30%,Ca^(2+)浓度降低20%(P<0.05或P<0.01)。[结论]琥珀酸/GPR91可能通过影响线粒体嵴稳态下调DHODH的表达进而抑制氧化型CoQ10还原,导致线粒体损伤。

新型吡唑乙酰胺类琥珀酸脱氢酶抑制剂的设计、合成及抑菌活性

为开发出新型杀菌剂候选分子,通过柔性改造吡唑甲酰胺杀菌剂结构中的二元酰胺键得到了一系列潜在靶向真菌琥珀酸脱氢酶(SDH)的新型吡唑乙酰胺分子.借助菌丝生长速率法发现了其中具有广谱抑菌特性的二苯醚联吡唑乙酰胺分子(6l),其在药剂质量浓度为50μg/mL时对水稻纹枯病菌、小麦赤霉病菌和草莓灰霉病菌的抑制效果均优于对照药剂噁霉灵.化合物6l对水稻纹枯病菌的半最大效应浓度(EC_(50)值)为19.92μg/mL,抑菌活性明显优于对照药剂噁霉灵和氟吡菌酰胺(EC_(50)分别为76.74和40.36μg/mL).SDH酶活力测试结果表明,真菌体内的SDH是化合物6l抑制水稻纹枯病菌生长的潜在作用靶标.分子对接研究结果显示,化合物6l分子结构中的二苯醚单元能以多种方式与靶标口袋的关键残基结合,对分子发挥抑菌活性起到了关键作用.研究结果表明,二苯醚联吡唑乙酰胺分子对植物病原真菌具有较显著的抑制作用,在其结构基础上进行深度的优化和改造有望得到可有效防控植物病原真菌的新型杀菌剂候选分子.

丙二酸二钠通过抑制琥珀酸脱氢酶活性损伤人精子运动功能

目的 揭示琥珀酸脱氢酶(SDH)在人精子功能调控中的作用。方法 将分离纯化后的人精子样本与不同浓度(10、20、40 mmol/L)SDH抑制剂丙二酸二钠共孵育不同时间(1、2 h)后,试剂盒检测对照组及丙二酸二钠处理组SDH酶活性,Western blot检测SDH催化亚基(SDHA)蛋白水平。精子功能研究实验:1)通过计算机辅助精液分析系统检测丙二酸二钠对未获能精子重要运动参数[前向运动率(PR)、总活力(TM)、平均路径速度(VAP)]以及获能精子穿透粘性介质能力的影响;2)伊红-苯胺黑法评估丙二酸二钠对精子存活率的作用;3)PSA-FITC染色法检测丙二酸二钠处理对获能精子顶体反应发生率的影响。结果 丙二酸二钠不改变人精子中琥珀酸脱氢酶A(SDHA)蛋白表达水平,但其能够抑制SDH酶催化活性、精子前向运动率、总活力以及获能精子穿透粘性介质的能力,且上述抑制效应同丙二酸二钠浓度正相关。此外,丙二酸二钠不影响获能精子自发顶体反应发生率。结论 丙二酸二钠通过抑制SDH活性损伤人精子运动功能。

琥珀酸脱氢酶缺陷型胃肠道间质瘤1例并文献复习

琥珀酸脱氢酶(SDH)缺陷型胃肠道间质瘤(GIST)是一组独特的GIST,患者以中青年女性居多,临床表现无特异性。组织病理学特征以上皮细胞型为主,生长方式多呈丛状或多结节方式生长。诊断依赖于病理免疫组织化学SDHB阴性或弱阳性。手术切除仍然是可切除的SDH缺陷型GIST的首选治疗,传统靶向治疗疗效有限。本文介绍1例31岁的女性SDH缺陷型GIST病例,该患者因体检发现腹腔巨大占位,而后顺利进行手术切除,病理提示SDH缺陷型GIST,术后7个月复发,未治疗,规律随访,目前病灶仍稳定。此外,本文还进行了文献复习,以了解SDH缺陷型GIST的临床表现和病理特征,以便及时诊断和管理SDH缺陷型GIST。