scholarly journals Thioredoxin reductase

2000 ◽  
Vol 346 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Debbie MUSTACICH ◽  
Garth POWIS

The mammalian thioredoxin reductases (TrxRs) are a family of selenium-containing pyridine nucleotide-disulphide oxidoreductases with mechanistic and sequence identity, including a conserved -Cys-Val-Asn-Val-Gly-Cys- redox catalytic site, to glutathione reductases. TrxRs catalyse the NADPH-dependent reduction of the redox protein thioredoxin (Trx), as well as of other endogenous and exogenous compounds. The broad substrate specificity of mammalian TrxRs is due to a second redox-active site, a C-terminal -Cys-SeCys- (where SeCys is selenocysteine), that is not found in glutathione reductase or Escherichia coli TrxR. There are currently two confirmed forms of mammalian TrxRs, TrxR1 and TrxR2, and it is possible that other forms will be identified. The availability of Se is a key factor determining TrxR activity both in cell culture and in vivo, and the mechanism(s) for the incorporation of Se into TrxRs, as well as the regulation of TrxR activity, have only recently begun to be investigated. The importance of Trx to many aspects of cell function make it likely that TrxRs also play a role in protection against oxidant injury, cell growth and transformation, and the recycling of ascorbate from its oxidized form. Since TrxRs are able to reduce a number of substrates other than Trx, it is likely that additional biological effects will be discovered for TrxR. Furthermore, inhibiting TrxR with drugs may lead to new treatments for human diseases such as cancer, AIDS and autoimmune diseases.

2018 ◽  
Vol 115 (51) ◽  
pp. 12967-12972 ◽  
Author(s):  
Rubén M. Buey ◽  
David Fernández-Justel ◽  
José M. de Pereda ◽  
José L. Revuelta ◽  
Peter Schürmann ◽  
...  

Ferredoxin-dependent thioredoxin reductase was identified 35 y ago in the fermentative bacterium Clostridium pasteurianum [Hammel KE, Cornwell KL, Buchanan BB (1983) Proc Natl Acad Sci USA 80:3681–3685]. The enzyme, a flavoprotein, was strictly dependent on ferredoxin as reductant and was inactive with either NADPH or NADH. This early work has not been further pursued. We have recently reinvestigated the problem and confirmed that the enzyme, here designated ferredoxin-dependent flavin thioredoxin reductase (FFTR), is a flavoprotein. The enzyme differs from ferredoxin−thioredoxin reductase (FTR), which has a signature [4Fe−4S] cluster, but shows structural similarities to NADP-dependent thioredoxin reductase (NTR). Comparative amino acid sequence analysis showed that FFTR is present in a number of clostridial species, some of which lack both FTR and an archetypal NTR. We have isolated, crystallized, and determined the structural properties of FFTR from a member of this group, Clostridium acetobutylicum, both alone and in complex with Trx. The structures showed an elongated FFTR homodimer, each monomer comprising two Rossmann domains and a noncovalently bound FAD cofactor that exposes the isoalloxazine ring to the solvent. The FFTR structures revealed an alternative domain organization compared with NTR that enables the enzyme to accommodate Fdx rather than NADPH. The results suggest that FFTR exists in a range of conformations with varying degrees of domain separation in solution and that the stacking between the two redox-active groups for the transfer of reducing equivalents results in a profound structural reorganization. A mechanism in accord with the findings is proposed.


2007 ◽  
Vol 388 (10) ◽  
pp. 1083-1090 ◽  
Author(s):  
Roland Geisberger ◽  
Claudia Kiermayer ◽  
Cornelia Hömig ◽  
Marcus Conrad ◽  
Jörg Schmidt ◽  
...  

Abstract Thioredoxin reductases (Txnrds) are a group of selenoenzymes participating in cellular redox regulation. Three Txnrd isoforms are known, each of which exhibits distinct cellular localisation and tissue-specific expression pattern. Txnrd1 is found in the cytoplasm, expression of Txnrd2 is restricted to mitochondria and Txnrd3 shows testis-specific expression. Recently, it was shown that Txnrd2 strongly affects the development of blood cells, since mouse embryos deficient for Txnrd2 are severely anaemic, show increased apoptosis in foetal liver and possess haematopoietic liver stem cells of reduced capacity to proliferate in vitro. However, because Txnrd2-deficient mice die at embryonic day 13.5, it was not known how this enzyme affects blood cell function in the adult animal. In the present study we show that conditional Txnrd2 knockouts generated using CD4- and CD19Cre transgenic mice lack Txnrd2 expression in CD4-- and CD19-positive T- and B-lymphocytes, respectively. However, the development and differentiation of both cell types in thymus and bone marrow was not significantly impaired. In addition, B-cell proliferation and activation in response to CD40 and IL-4 was unaltered in Txnrd2-deficient B-cells.


2005 ◽  
Vol 25 (5) ◽  
pp. 1980-1988 ◽  
Author(s):  
Cemile Jakupoglu ◽  
Gerhard K. H. Przemeck ◽  
Manuela Schneider ◽  
Stéphanie G. Moreno ◽  
Nadja Mayr ◽  
...  

ABSTRACT Two distinct thioredoxin/thioredoxin reductase systems are present in the cytosol and the mitochondria of mammalian cells. Thioredoxins (Txn), the main substrates of thioredoxin reductases (Txnrd), are involved in numerous physiological processes, including cell-cell communication, redox metabolism, proliferation, and apoptosis. To investigate the individual contribution of mitochondrial (Txnrd2) and cytoplasmic (Txnrd1) thioredoxin reductases in vivo, we generated a mouse strain with a conditionally targeted deletion of Txnrd1. We show here that the ubiquitous Cre-mediated inactivation of Txnrd1 leads to early embryonic lethality. Homozygous mutant embryos display severe growth retardation and fail to turn. In accordance with the observed growth impairment in vivo, Txnrd1-deficient embryonic fibroblasts do not proliferate in vitro. In contrast, ex vivo-cultured embryonic Txnrd1-deficient cardiomyocytes are not affected, and mice with a heart-specific inactivation of Txnrd1 develop normally and appear healthy. Our results indicate that Txnrd1 plays an essential role during embryogenesis in most developing tissues except the heart.


2021 ◽  
Vol 12 (9) ◽  
Author(s):  
An Xie ◽  
Xinping Xu ◽  
Peng Kuang ◽  
Ling Zhang ◽  
Feng Yu

AbstractLung squamous cell carcinoma (LUSC) has a poor clinical prognosis and lacks effective targeted therapy. The transmembrane emp24 trafficking protein 3 (TMED3) belongs to the TMED family, which is responsible for the transport of intracellular proteins. This study was to explore the clinicopathological significance and biological effects of TMED3 in LUSC. Expression of TMED3 in LUSC was detected by immunohistochemical (IHC). The loss-of-function assays were used to investigate the effects of TMED3 on proliferation, apoptosis, cell cycle, and migration of LUSC cells. The influence of TMED3 knockdown on tumor growth in vivo was evaluated by mice xenograft models. In addition, the downstream target of TMED3 was recognized by RNA sequencing and Ingenuity Pathway Analysis (IPA). Moreover, TMED3 was upregulated in LUSC tissue, which was positively correlated with pathological grade. TMED3 knockdown was involved in the regulation of LUSC cell function, such as inhibition of proliferation, reduction of colony formation, induction of apoptosis, and reduction of migration. TMED3 knockdown induced abnormalities in apoptosis-related proteins in LUSC cells. In addition, the inhibition of cell migration by TMED3 knockdown was achieved by regulating EMT. Mechanically, EZR was considered as a potential target for TMED3 to regulate the progress of LUSC. Inhibition of EZR can inhibit the progression of LUSC, and even reduce the promoting effects of TMED3 overexpression on LUSC. In conclusion, TMED3 promoted the progression and development of LUSC by EZR, which may be a novel therapeutic target for LUSC.


2020 ◽  
Vol 295 (52) ◽  
pp. 18134-18147
Author(s):  
Xin Xu ◽  
Yihua Zhang ◽  
Junjie Zhang ◽  
Xiaotian Zhang

NSun2 is an RNA methyltransferase introducing 5-methylcytosine into tRNAs, mRNAs, and noncoding RNAs, thereby influencing the levels or function of these RNAs. Autotaxin (ATX) is a secreted glycoprotein and is recognized as a key factor in converting lysophosphatidylcholine into lysophosphatidic acid (LPA). The ATX-LPA axis exerts multiple biological effects in cell survival, migration, proliferation, and differentiation. Here, we show that NSun2 is involved in the regulation of cell migration through methylating ATX mRNA. In the human glioma cell line U87, knockdown of NSun2 decreased ATX protein levels, whereas overexpression of NSun2 elevated ATX protein levels. However, neither overexpression nor knockdown of NSun2 altered ATX mRNA levels. Further studies revealed that NSun2 methylated the 3′-UTR of ATX mRNA at cytosine 2756 in vitro and in vivo. Methylation by NSun2 enhanced ATX mRNA translation. In addition, NSun2-mediated 5-methylcytosine methylation promoted the export of ATX mRNA from nucleus to cytoplasm in an ALYREF-dependent manner. Knockdown of NSun2 suppressed the migration of U87 cells, which was rescued by the addition of LPA. In summary, we identify NSun2-mediated methylation of ATX mRNA as a novel mechanism in the regulation of ATX.


2018 ◽  
Author(s):  
Francois Brial ◽  
Fawaz Alzaid ◽  
Kazuhiro Sonomura ◽  
Kelly Meneyrol ◽  
Aurélie Le Lay ◽  
...  

SUMMARYGut microbiota changes are associated with increased risk of Type 2 diabetes (T2D) and obesity. Through serum metabolome profiling in patients with cardiometabolic disease (CMD) we identified significant inverse correlation between the microbial metabolite 4-cresol and T2D. Chronic administration of non toxic dose of 4-cresol in two complementary preclinical models of CMD reduced adiposity, glucose intolerance and liver triglycerides, and enhanced insulin secretion in vivo, which may be explained by markedly increased pancreas weight, augmented islet density and size, and enhanced vascularisation suggesting activated islet neogenesis. Incubation of isolated islets with 4-cresol enhanced insulin secretion, insulin content and cell proliferation. In both CMD models 4-cresol treatment in vivo was associated with altered expression of SIRT1 and the kinase DYRK1A, which may contribute to mediate its biological effects. Our findings identify 4-cresol as an effective regulator of β-cell function and T2D endophenotypes, which opens therapeutic perspectives in syndromes of insulin deficiency.


2020 ◽  
Vol 246 (3) ◽  
pp. 223-236 ◽  
Author(s):  
Xiaoyi Ma ◽  
Fei Gao ◽  
Qi Chen ◽  
Xiuping Xuan ◽  
Ying Wang ◽  
...  

The angiotensin-converting enzyme 2 (ACE2)/angiotensin 1–7 (A1–7)/MAS axis and glutamate decarboxylase 67 (GAD67)/gamma-aminobutyric acid (GABA) signal both exist in the islet and play important roles in regulating blood glucose metabolism. It has been reported that the activation of ACE2 in the brain increases GABA expression to improve biological effects; however, it is unclear whether there is functional correlation between the ACE2/A1–7/MAS axis and GAD67/GABA signal in the islet. In this study, we showed that the ACE2/A1–7/MAS and GABA signaling systems decreased in the islet of different metabolic stress models. In ACE2-knockout mice, we found that GAD67 and GABA expression decreased significantly, which was reversed by exogenous administration of A1–7. Furthermore, A1–7 mediated PDX1 and AKT activation was inhibited by allylglycine (a specific GAD67 inhibitor) in MIN6 cells. Moreover, giving A1–7 and GABA could significantly reduce beta-cell dedifferentiation and improved glucose metabolism during metabolic stress in vivo and in vitro. In conclusion, our study reveals that the ACE2/A1–7/MAS axis improves beta-cell function through regulating GAD67/GABA signal in beta cells and that up-regulating the ACE2/A1–7/MAS axis and GABA signals delays the development of obesity-induced diabetes.


Author(s):  
Н.В. Белобородова ◽  
В.В. Мороз ◽  
А.Ю. Бедова

Интеграция метаболизма макроорганизма и его микробиоты, обеспечивающая в норме симбиоз и саногенез, нарушается при заболеваниях, травме, критическом состоянии, и вектор взаимодействия может изменяться в пользу прокариотов по принципу «метаболиты бактерий - против хозяина». Анализ литературы показал, что, с одной стороны, имеется живой интерес к ароматическим микробным метаболитам, с другой - отсутствует четкое представление об их роли в организме человека. Публикации, касающиеся ряда ароматических микробных метаболитов (фенилкарбоновых кислот, ФКК), как правило, не связаны между собой по тематике и направлены на решение тех или иных прикладных задач в разных областях биологии и медицины. Цель обзора - анализ информации о происхождении, биологических эффектах ФКК в экспериментах in vitro и in vivo , и клинических наблюдениях. Обобщая результаты приведенных в обзоре исследований на клеточном, субклеточном и молекулярном уровнях, логично предположить участие ароматических микробных метаболитов в патогенезе полиорганной недостаточности при сепсисе. Наиболее перспективным для раскрытия роли ароматических микробных метаболитов представляется изучение механизмов вторичной почечной недостаточности и септической энцефалопатии. Важным направлением для будущих исследований является изучение влияния продуктов микробной биодеградации ароматических соединений на развитие диссеминированного внутрисосудистого свертывания крови, артериальной гипотензии и септического шока. Результаты дальнейших исследований будут иметь не только фундаментальное значение, но и обогатят практическую медицину новыми диагностическими и лечебными технологиями. Significant increases in blood concentrations of some aromatic metabolites (phenylcarboxylic acids, PhCAs) in patients with sepsis have been previously shown. Enhanced bacterial biodegradation of aromatic compounds has been demonstrated to considerably contribute to this process. Integration of macroorganism metabolism and its microbiota, which provides normal symbiosis and sanogenesis, is disturbed in diseases, trauma, and critical conditions. Direction of this interaction may change in favor of prokaryotes according to the principle, “bacterial metabolites are against the host”. Analysis of literature showed a particular interest of many investigators to aromatic microbial metabolites. However, there is no clear understanding of their role in the human body. Publications on PhCAs are generally not thematically interrelated and usually focus on solving applied tasks in different fields of biology and medicine. The aim of this work was to consolidate existing information about origin and biological effects of PhCAs in in vitro / in vivo experiments and some clinical findings. The presented summary of reported data from studies performed at cellular, sub-cellular, and molecular levels suggests participation of aromatic microbial metabolites in the pathogenesis of multiple organ failure in sepsis. Studying mechanisms of secondary renal failure and septic encephalopathy is most promising for discovering the function of aromatic microbial metabolites. Effects of microbial biodegradation products of aromatic substances on development of disseminated intravascular coagulation, hypotension, and septic shock are an important challenge for future studies. Results of further investigations will be not only fundamental, but will also enrich medical practice with new diagnostic and therapeutic technologies.


2019 ◽  
Author(s):  
C. Tigrine ◽  
A. Kameli

In this study a polyphenolic extract from Cleome arabica leaves (CALE) was investigated for its antioxidant activity in vitro using DPPH•, metal chelating and reducing power methods and for its protective effects against AraC-induced hematological toxicity in vivo using Balb C mice. Results indicated that CALE exhibited a strong and dose-dependent scavenging activity against the DPPH• free radical (IC50 = 4.88 μg/ml) and a high reducing power activity (EC50 = 4.85 μg/ml). Furthermore, it showed a good chelating effects against ferrous ions (IC50 = 377.75 μg/ml). The analysis of blood showed that subcutaneous injection of AraC (50 mg/kg) to mice during three consecutive days caused a significant myelosupression (P < 0.05). The combination of CALE and AraC protected blood cells from a veritable toxicity. Where, the number of the red cells, the amount of hemoglobin and the percentage of the hematocrite were significantly high. On the other hand, AraC cause an elevation of body temperature (39 °C) in mice. However, the temperature of the group treated with CALE and AraC remained normal and did not exceed 37.5 °C. The observed biological effects of CALE, in vitro as well as in vivo, could be due to the high polyphenol and flavonoid contents. In addition, the antioxidant activity of CALE suggested to be responsible for its hematoprotective effect.


2019 ◽  
Vol 26 (7) ◽  
pp. 494-501 ◽  
Author(s):  
Sameer Suresh Bhagyawant ◽  
Dakshita Tanaji Narvekar ◽  
Neha Gupta ◽  
Amita Bhadkaria ◽  
Ajay Kumar Gautam ◽  
...  

Background: Diabetes and hypertension are the major health concern and alleged to be of epidemic proportions. This has made it a numero uno subject at various levels of investigation. Glucosidase inhibitor provides the reasonable option in treatment of Diabetes Mellitus (DM) as it specifically targets post prandial hyperglycemia. The Angiotensin Converting Enzyme (ACE) plays an important role in hypertension. Therefore, inhibition of ACE in treatment of elevated blood pressure attracts special interest of the scientific community. Chickpea is a food legume and seeds contain carbohydrate binding protein- a lectin. Some of the biological properties of this lectin hitherto been elucidated. Methods: Purified by ion exchange chromatography, chickpea lectin was tested for its in vitro antioxidant, ACE-I inhibitory and anti-diabetic characteristic. Results: Lectin shows a characteristic improvement over the synthetic drugs like acarbose (oral anti-diabetic drug) and captopril (standard antihypertensive drug) when, their IC50 values are compared. Lectin significantly inhibited α-glucosidase and α-amylase in a concentration dependent manner with IC50 values of 85.41 ± 1.21 ҝg/ml and 65.05 ± 1.2 µg/ml compared to acarbose having IC50 70.20 ± 0.47 value of µg/ml and 50.52 ± 1.01 µg/ml respectively. β-Carotene bleaching assay showed antioxidant activity of lectin (72.3%) to be as active as Butylated Hydroxylanisole (BHA). In addition, lectin demonstrated inhibition against ACE-I with IC50 value of 57.43 ± 1.20 µg/ml compared to captopril. Conclusion: Lectin demonstrated its antioxidant character, ACE-I inhibition and significantly inhibitory for α-glucosidase and α-amylase seems to qualify as an anti-hyperglycemic therapeutic molecule. The biological effects of chickpea lectin display potential for reducing the parameters of medically debilitating conditions. These characteristics however needs to be established under in vivo systems too viz. animals through to humans.


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