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1.
Julie Herman Nicolas Thelen Nicolas Smargiasso Anne-Catherine Mailleux André Luxen Marie Cloes Edwin De Pauw Andy Chevigné Moreno Galleni Marie-Eve Dumez 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
The enzymatic activity of the four proteases found in the house dust mite Dermatophagoides pteronyssinus is involved in the pathogenesis of allergy. Our aim was to elucidate the activation cascade of their corresponding precursor forms and particularly to highlight the interconnection between proteases during this cascade.Methods
The cleavage of the four peptides corresponding to the mite zymogen activation sites was studied on the basis of the Förster Resonance Energy Transfer method. The proDer p 6 zymogen was then produced in Pichia pastoris to elucidate its activation mechanism by mite proteases, especially Der p 1. The role of the propeptide in the inhibition of the enzymatic activity of Der p 6 was also examined. Finally, the Der p 1 and Der p 6 proteases were localised via immunolocalisation in D. pteronyssinus.Results
All peptides were specifically cleaved by Der p 1, such as proDer p 6. The propeptide of proDer p 6 inhibited the proteolytic activity of Der p 6, but once cleaved, it was degraded by the protease. The Der p 1 and Der p 6 proteases were both localised to the midgut of the mite.Conclusions
Der p 1 in either its recombinant form or in the natural context of house dust mite extracts specifically cleaves all zymogens, thus establishing its role as a major activator of both mite cysteine and serine proteases.General significance
This finding suggests that Der p 1 may be valuable target against mites. 相似文献2.
Background
Mitochondria are multifunctional organelles that not only serve as cellular energy stores but are also actively involved in several cellular stress responses, including apoptosis. In addition, mitochondria themselves are also continuously challenged by stresses such as reactive oxygen species (ROS), an inevitable by-product of oxidative phosphorylation. To exert various functions against these stresses, mitochondria must be equipped with appropriate stress responses that monitor and maintain their quality.Scope of review
Interestingly, increasing evidence indicates that mitochondrial proteolysis has important roles in mitochondrial and cellular stress responses. In this review, we summarize current advances in mitochondrial proteolysis-mediated stress responses.Major conclusions
Mitochondrial proteases do not only function as surveillance systems of protein quality control by degrading unfolded proteins but also regulate mitochondrial stress responses by processing specific mitochondrial proteins.General significance
Studies on the regulation of mitochondrial proteolysis-mediated stress responses will provide the novel mechanistic insights into the stress response research fields. 相似文献3.
Milica M. Grozdanović Branko J. Drakulić Marija Gavrović-Jankulović 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Actinidin, a protease from kiwifruit, belongs to the C1 family of cysteine proteases. Cysteine proteases were found to be involved in many disease states and are valid therapeutic targets. Actinidin has a wide pH activity range and wide substrate specificity, which makes it a good model system for studying enzyme–substrate interactions.Methods
The influence of inhibitor (E-64) binding on the conformation of actinidin was examined by 2D PAGE, circular dichroism (CD) spectroscopy, hydrophobic ligand binding assay, and molecular dynamics simulations.Results
Significant differences were observed in electrophoretic mobility of proteolytically active and E-64-inhibited actinidin. CD spectrometry and hydrophobic ligand binding assay revealed a difference in conformation between active and inhibited actinidin. Molecular dynamics simulations showed that a loop defined by amino-acid residues 88–104 had greater conformational mobility in the inhibited enzyme than in the active one. During MD simulations, the covalently bound inhibitor was found to change its conformation from extended to folded, with the guanidino moiety approaching the carboxylate.Conclusions
Conformational mobility of actinidin changes upon binding of the inhibitor, leading to a sequence of events that enables water and ions to protrude into a newly formed cavity of the inhibited enzyme. Drastic conformational mobility of E-64, a common inhibitor of cysteine proteases found in many crystal structures stored in PDB, was also observed.General significance
The analysis of structural changes which occur upon binding of an inhibitor to a cysteine protease provides a valuable starting point for the future design of therapeutic agents. 相似文献4.
Thomas Ross Karol Szczepanek Elizabeth Bowler Ying Hu Andrew Larner Edward J. Lesnefsky Qun Chen 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
The reverse electron flow-induced ROS generation (RFIR) is decreased in ischemia-damaged mitochondria. Cardiac ischemia leads to decreased complex I activity and depolarized inner mitochondrial membrane potential (ΔΨ) that are two key factors to affect the RFIR in isolated mitochondria. We asked if a partial inhibition of complex I activity without alteration of the ΔΨ is able to decrease the RFIR.Methods
Cardiac mitochondria were isolated from mouse heart (C57BL/6) with and without ischemia. The rate of H2O2 production from mitochondria was determined using amplex red coupled with horseradish peroxidase. Mitochondria were isolated from the mitochondrial-targeted STAT3 overexpressing mouse (MLS-STAT3E) to clarify the role of partial complex I inhibition in RFIR production.Results
The RFIR was decreased in ischemia-damaged mouse heart mitochondria with decreased complex I activity and depolarized ΔΨ. However, the RFIR was not altered in the MLS-STAT3E heart mitochondria with complex I defect but without depolarization of the ΔΨ. A slight depolarization of the ΔΨ in wild type mitochondria completely eliminated the RFIR.Conclusions
The mild uncoupling but not the partially decreased complex I activity contributes to the observed decrease in RFIR in ischemia-damaged mitochondria.General significance
The RFIR is less likely to be a key source of cardiac injury during reperfusion. 相似文献5.
Aims
The molecular mechanism(s) by which extracellular signal-regulated kinase 1/2 (ERK1/2) and other kinases communicate with downstream targets have not been fully determined. Multiprotein signaling complexes undergoing spatiotemporal redistribution may enhance their interaction with effector proteins promoting cardioprotective response. Particularly, it has been proposed that some active kinases in association with caveolae may converge into mitochondria. Therefore, in this study we investigate if PHO-ERK1/2 interaction with mitochondria may provide a mechanistic link in the regulation of these organelles in cardioprotective signaling.Main methods
Using a model of dilated cardiomyopathy followed by ischemia–reperfusion injury, we determined ERK1/2 signaling at the level of mitochondria and evaluated its effect on the permeability transition pore.Key findings
The most important finding of the present study is that, under cardioprotective conditions, a subpopulation of activated ERK1/2 was directed to the mitochondrial membranes through vesicular trafficking, concurring with increased phosphorylation of mitochondrial proteins and inhibition of the mitochondrial permeability transition pore opening. In addition, our results suggest that vesicles enriched with caveolin-3 could form structures that may drive ERK1/2, GSK3β and Akt to mitochondria.Significance
Signaling complexes including PHO-ERK, PHO-Akt, PHO-eNOS and caveolin-3 contribute to cardioprotection by directly targeting the mitochondrial proteome and regulating the opening of the permeability transition pore in this model. 相似文献6.
Xiu-Zhen Wu Ai-Xia Cheng Ling-Mei Sun Shu-Juan Sun Hong-Xiang Lou 《Biochimica et Biophysica Acta (BBA)/General Subjects》2009
Background
Plagiochin E (PLE) is an antifungal macrocyclic bis(bibenzyl) isolated from liverwort Marchantia polymorpha L. Its antifungal mechanism is unknown. To elucidate the mechanism of action, its effect on mitochondria function in Candida albicans was studied.Methods
We assayed the mitochondrial membrane potential (mtΔψ) using rhodamine 123, measured ATP level in mitochondria by HPLC, and detected the activities of mitochondrial F0F1-ATPase and dehydrogenases. Besides, the mitochondrial dysfunction-induced reactive oxygen species (ROS) production was determined by a fluorometric assay, and the effects of antioxidant L-cysteine on PLE-induced ROS production and the antifungal effect of PLE on C. albicans were also investigated.Results
Exposure to PLE resulted in an elevation of mtΔψ, and a decrease of ATP level in mitochondria. The ATP depletion owed to PLE-induced enhancement of mitochondrial F0F1-ATPase and inhibition of the mitochondrial dehydrogenases. These dysfunctions of mitochondria caused ROS accumulation in C. albicans, and this increase in the level of ROS production and PLE-induced decrease in cell viability were prevented by addition of L-cysteine, indicating that ROS was an important mediator of the antifungal action of PLE.Conclusions
PLE exerts its antifungal activity through mitochondrial dysfunction-induced ROS accumulation in C. albicans.General significance
The effect of PLE on the mitochondria function in C. albicans was assayed for the first time. These results would conduce to elucidate its underlying antifungal mechanism. 相似文献7.
Sylvain Hanein Mathilde Garcia Lucas Fares-Taie Valérie Serre Yves De Keyzer Thierry Delaveau Isabelle Perrault Nathalie Delphin Sylvie Gerber Alain Schmitt Jean-Marc Masse Arnold Munnich Josseline Kaplan Frédéric Devaux Jean-Michel Rozet 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Hereditary optic neuropathies (HONs) are a heterogeneous group of disorders that affect retinal ganglion cells (RGCs) and axons that form the optic nerve. Leber's Hereditary Optic Neuropathy and the autosomal dominant optic atrophy related to OPA1 mutations are the most common forms. Nonsyndromic autosomal recessive optic neuropathies are rare and their existence has been long debated. We recently identified the first gene responsible for these conditions, TMEM126A. This gene is highly expressed in retinal cellular compartments enriched in mitochondria and supposed to encode a mitochondrial transmembrane protein of unknown function.Methods
A specific polyclonal antibody targeting the TMEM126A protein has been generated. Quantitative fluorescent in situ hybridization, cellular fractionation, mitochondrial membrane association study, mitochondrial sub compartmentalization analysis by both proteolysis assays and transmission electron microscopy, and expression analysis of truncated TMEM126A constructs by immunofluorescence confocal microscopy were carried out.Results
TMEM126A mRNAs are strongly enriched in the vicinity of mitochondria and encode an inner mitochondrial membrane associated cristae protein. Moreover, the second transmembrane domain of TMEM126A is required for its mitochondrial localization.Conclusions
TMEM126A is a mitochondrial located mRNA (MLR) that may be translated in the mitochondrial surface and the protein is subsequently imported to the inner membrane. These data constitute the first step toward a better understanding of the mechanism of action of TMEM126A in RGCs and support the importance of mitochondrial dysfunction in the pathogenesis of HON.General significance
Local translation of nuclearly encoded mitochondrial mRNAs might be a mechanism for rapid onsite supply of mitochondrial membrane proteins. 相似文献8.
Fatemeh Shaki Mir-Jamal Hosseini Mahmoud Ghazi-Khansari Jalal Pourahmad 《Biochimica et Biophysica Acta (BBA)/General Subjects》2012
Background
Kidney is known as the most sensitive target organ for depleted uranium (DU) toxicity in comparison to other organs. Although the oxidative stress and mitochondrial damage induced by DU has been well investigated, the precise mechanism of DU-induced nephrotoxicity has not been thoroughly recognized yet.Methods
Kidney mitochondria were obtained using differential centrifugation from Wistar rats and mitochondrial toxicity endpoints were then determined in both in vivo and in vitro uranyl acetate (UA) exposure cases.Results
Single injection of UA (0, 0.5, 1 and 2 mg/kg, i.p.) caused a significant increase in blood urea nitrogen and creatinine levels. Isolated mitochondria from the UA-treated rat kidney showed a marked elevation in oxidative stress accompanied by mitochondrial membrane potential (MMP) collapse as compared to control group. Incubation of isolated kidney mitochondria with UA (50, 100 and 200 μM) manifested that UA can disrupt the electron transfer chain at complex II and III that leads to induction of reactive oxygen species (ROS) formation, lipid peroxidation, and glutathione oxidation. Disturbances in oxidative phosphorylation were also demonstrated through decreased ATP concentration and ATP/ADP ratio in UA-treated mitochondria. In addition, UA induced a significant damage in mitochondrial outer membrane. Moreover, MMP collapse, mitochondrial swelling and cytochrome c release were observed following the UA treatment in isolated mitochondria.General significance
Both our in vivo and in vitro results showed that UA-induced nephrotoxicity is linked to the impairment of electron transfer chain especially at complex II and III which leads to subsequent oxidative stress. 相似文献9.
Background
Aspartic proteases Cathepsin (Cath) E and D are two different proteases, but they share many common characteristics, including molecular weight, catalytic mechanism, substrate preferences, proteolytic conditions and inhibition susceptibility. To define the biological roles of these proteases, it is necessary to elucidate their substrate specificity. In the present study, we report a new peptide–substrate that is only sensitive to Cath E but not Cath D.Methods
Substrate e, Mca-Ala-Gly-Phe-Ser-Leu-Pro-Ala-Lys(Dnp)-DArg-CONH2, designed in such a way that due to the close proximity of a Mca-donor and a Dnp-acceptor, near complete intramolecular quenching effect was achieved in its intact state. After the proteolytic cleavage of the hydrophobic motif of peptide substrate, both Mca and Dnp would be further apart, resulting in bright fluorescence.Results
Substrate e showed a 265 fold difference in the net fluorescence signals between Cath E and D. This Cath E selectivity was established by having -Leu**Pro- residues at the scissile peptide bond. The confined cleavage site of substrate e was confirmed by LC-MS. The catalytic efficiency (Kcat/KM) of Cath E for substrate e was 16.7 μM−1 S−1. No measurable catalytic efficiency was observed using Cath D and no detectable fluorescent changes when incubated with Cath S and Cath B.Conclusions
This study demonstrated the promise of using the developed fluorogenic substrate e as a selective probe for Cath E proteolytic activity measurement.General significance
This study forms the foundation of Cath E specific inhibitor development in further studies. 相似文献10.
Peter Schönfeld Nicol Kruska Georg Reiser 《Biochimica et Biophysica Acta (BBA)/General Subjects》2009,1790(12):1698-1704
Background
Hydroxy-1-aryl-isochromans (HAIC) are newly emerging natural polyphenolic antioxidants, enriched in extravirgin olive oil, whose antioxidative potency was only scarcely characterized using cell-free systems and cells.Methods
We characterized the activity of HAIC to inactivate reactive oxygen species (ROS) generated by the xanthine/xanthine oxidase system, mitochondria (rat brain) and neural cells. ROS levels were estimated using ROS-sensitive probes, such as Amplex Red, MitoSOXRED.Results
HAIC (with 2, 3 or 4 hydroxyl substituents) effectively scavenge ROS released from mitochondria. EC50 values estimated with mitochondria and submitochondrial particles were around 20 μM. Moreover, in PC12 and cultured neural primary cells, HAIC buffered cytosolic ROS. Although HAIC permeate biological membranes, HAIC fail to buffer matrix ROS in isolated mitochondria. We show that hydrogen peroxide was effectively abolished by HAIC, whereas the production of superoxide was not affected.Conclusion
HAIC exert high antioxidative activity to reduce hydrogen peroxide. The antioxidative activity of HAIC is comparable with that of the stilbene-like, polyphenolic resveratrol, but much higher than that of trolox, N-acetylcysteine or melatonin.General significance
Unlike resveratrol, HAIC do not impair mitochondrial ATP synthesis or Ca2+ retention by mitochondria. Thus, HAIC have the decisive advantage to be potent antioxidants with no detrimental side effects on mitochondrial functions. 相似文献11.
Arti Parihar Mordhwaj S. Parihar Rafal Nazarewicz Pedram Ghafourifar 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Background
Ceramides are intracellular lipid mediator implicated in various cellular responses, including oxidative stress and programmed cell death. Studies demonstrated strong links between ceramide and the mitochondria in the regulation of apoptosis. However, the mechanism of apoptosis induced by ceramides is not fully understood. The present study delineates importance of the redox state of cytochrome c for release of cytochrome c and apoptosis of human mammary adenocarcinoma MCF-7 and MDA-MB-231 cells induced by ceramides.Methods
The study uses MCF-7 and MDA-MB-231 cells, isolated mitochondria, submitochondrial particles, and oxidized and reduced cytochrome c. Methods used include flow cytometry, immunoblotting, spectroscopy, and respirometry.Results
We show that ceramides induce mitochondrial oxidative stress and release of cytochrome c from the mitochondria of these cells. Our findings show that ceramides react with oxidized cytochrome c whereas reduced cytochrome c does not react with ceramides. We also show that oxidized cytochrome c reacted with ceramides exerts lower reducibility and function to support mitochondrial respiration. Furthermore, our data show that glutathione protects cytochrome c of reacting with ceramides by increasing the reduced state of cytochrome c.Conclusions
Ceramides induce oxidative stress and apoptosis in human mammary adenocarcinoma cells by interacting with oxidized cytochrome c leading to the release of cytochrome c from the mitochondria. Our findings suggest a novel mechanism for protective role of glutathione.General significance
Our study suggests that the redox state of cytochrome c is important in oxidative stress and apoptosis induced by ceramides. 相似文献12.
Monika W. Murcha Yan Wang Reena Narsai James Whelan 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
Mitochondria play essential roles in the life and death of almost all eukaryotic cells, ranging from single-celled to multi-cellular organisms that display tissue and developmental differentiation. As mitochondria only arose once in evolution, much can be learned from studying single celled model systems such as yeast and applying this knowledge to other organisms. However, two billion years of evolution have also resulted in substantial divergence in mitochondrial function between eukaryotic organisms.Scope of Review
Here we review our current understanding of the mechanisms of mitochondrial protein import between plants and yeast (Saccharomyces cerevisiae) and identify a high level of conservation for the essential subunits of plant mitochondrial import apparatus. Furthermore, we investigate examples whereby divergence and acquisition of functions have arisen and highlight the emerging examples of interactions between the import apparatus and components of the respiratory chain.Major conclusions
After more than three decades of research into the components and mechanisms of mitochondrial protein import of plants and yeast, the differences between these systems are examined. Specifically, expansions of the small gene families that encode the mitochondrial protein import apparatus in plants are detailed, and their essential role in seed viability is revealed.General significance
These findings point to the essential role of the inner mitochondrial protein translocases in Arabidopsis, establishing their necessity for seed viability and the crucial role of mitochondrial biogenesis during germination. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research. 相似文献13.
The 30-kDa mitochondrial proteins induced by hormone stimulation in MA-10 mouse Leydig tumor cells are processed from larger precursors 总被引:4,自引:0,他引:4
Acute regulation of steroidogenesis in steroidogenic tissue is controlled by the transfer of cholesterol from the outer to the inner mitochondrial membrane where cleavage to produce pregnenolone occurs. Hormonal stimulation of MA-10 mouse Leydig tumor cells results in a large increase in steroidogenesis and the concomitant appearance of a series of 30-kDa proteins which have been localized to the mitochondria. In the present study we have shown that the appearance of these proteins occurs in a dose-responsive manner with both human chorionic gonadotropin and cyclic AMP analog. We have also shown that while steroidogenesis is inhibited rapidly in response to a cessation of protein synthesis, the 30-kDa mitochondrial proteins remain in the mitochondria, posing a potential dilemma for arguments favoring their role in the acute regulation of steroidogenesis. We report that the 30-kDa mitochondrial proteins arise from two precursor proteins with molecular masses of 37 and 32 kDa which are also found to be associated with the mitochondria. The use of pulse-chase experiments and the inhibitors ortho-phenanthroline and carbonyl cyanide m-chlorophenylhydrazone demonstrated the precursor-product relationship between the 37-, 32-, and 30-kDa proteins. We have also demonstrated that, as shown for a number of other mitochondrial proteins, the 30-kDa proteins are transferred to the inner mitochondrial membrane by a process requiring both proteolytic removal of the targeting sequences and an electrical potential across the inner mitochondrial membrane. We propose that during this transfer contact sites form between the two mitochondrial membranes and may offer an ideal situation for the transfer of cholesterol from the outer membrane to the inner membrane by an as yet unknown mechanism. Following transfer, the 30-kDa proteins remain in the inner membrane no longer able to function in the further transfer of cholesterol, and it is the continuing synthesis and processing of more precursor proteins which provides additional substrate for steroidogenesis. 相似文献
14.
Cibely Cristine Fontes-Oliveira Sílvia Busquets Míriam Toledo Fabio Penna Maria Paz Aylwin Sònia Sirisi Ana Paula Silva Marcel Orpí Albert García Angelica Sette Maria Inês Genovese Mireia Olivan Francisco J. López-Soriano Josep M. Argilés 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Cachexia is a wasting condition that manifests in several types of cancer, and the main characteristic is the profound loss of muscle mass.Methods
The Yoshida AH-130 tumor model has been used and the samples have been analyzed using transmission electronic microscopy, real-time PCR and Western blot techniques.Results
Using in vivo cancer cachectic model in rats, here we show that skeletal muscle loss is accompanied by fiber morphologic alterations such as mitochondrial disruption, dilatation of sarcoplasmic reticulum and apoptotic nuclei. Analyzing the expression of some factors related to proteolytic and thermogenic processes, we observed in tumor-bearing animals an increased expression of genes involved in proteolysis such as ubiquitin ligases Muscle Ring Finger 1 (MuRF-1) and Muscle Atrophy F-box protein (MAFBx). Moreover, an overexpression of both sarco/endoplasmic Ca2 +-ATPase (SERCA1) and adenine nucleotide translocator (ANT1), both factors related to cellular energetic efficiency, was observed. Tumor burden also leads to a marked decreased in muscle ATP content.Conclusions
In addition to muscle proteolysis, other ATP-related pathways may have a key role in muscle wasting, both directly by increasing energetic inefficiency, and indirectly, by affecting the sarcoplasmic reticulum–mitochondrial assembly that is essential for muscle function and homeostasis.General significance
The present study reports profound morphological changes in cancer cachectic muscle, which are visualized mainly in alterations in sarcoplasmic reticulum and mitochondria. These alterations are linked to pathways that can account for energy inefficiency associated with cancer cachexia. 相似文献15.
Background
While there is agreement that exercise is a powerful stimulus to increase both mitochondrial function and content, we do not know the optimal training stimulus to maximise improvements in mitochondrial biogenesis.Scope of review
This review will focus predominantly on the effects of exercise on mitochondrial function and content, as there is a greater volume of published research on these adaptations and stronger conclusions can be made.Major conclusions
The results of cross-sectional studies, as well as training studies involving rats and humans, suggest that training intensity may be an important determinant of improvements in mitochondrial function (as determined by mitochondrial respiration), but not mitochondrial content (as assessed by citrate synthase activity). In contrast, it appears that training volume, rather than training intensity, may be an important determinant of exercise-induced improvements in mitochondrial content. Exercise-induced mitochondrial adaptations are quickly reversed following a reduction or cessation of physical activity, highlighting that skeletal muscle is a remarkably plastic tissue. Due to the small number of studies, more research is required to verify the trends highlighted in this review, and further studies are required to investigate the effects of different types of training on the mitochondrial sub-populations and also mitochondrial adaptations in different fibre types. Further research is also required to better understand how genetic variants influence the large individual variability for exercise-induced changes in mitochondrial biogenesis.General significance
The importance of mitochondria for both athletic performance and health underlines the importance of better understanding the factors that regulate exercise-induced changes in mitochondrial biogenesis. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research. 相似文献16.
Junyan Han Myung Shin Han Ching-Hsuan Tung 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Mitochondria, powerhouses of cells, are responsible for many critical cellular functions, such as cell energy metabolism, reactive oxygen species production, and apoptosis regulation. Monitoring mitochondria morphology in live cells temporally and spatially could help with the understanding of the mechanisms of mitochondrial functional regulation and the pathogenesis of mitochondria-related diseases.Methods
A novel non-cytotoxic fluorogenic compound, AcQCy7, was developed as a mitochondria-specific dye.Results
AcQCy7 emitted no fluorescent signal outside of cells, but it became fluorescent after intracellular hydrolysis of the acetyl group. The hydrolyzed fluorescent product was well retained in mitochondria, enabling long-lasting fluorescence imaging of mitochondria without cell washing. A 2-day culture study using AcQCy7 showed no sign of cytotoxicity, whereas a commonly used mitochondria-staining probe, Mitochondria Tracker Green, caused significant cell death even at a much lower concentration. Apoptosis-causing mitochondria fission was monitored clearly in real time by AcQCy7.Conclusions
A simple add-and-read mitochondria specific dye AcQCy7 has been validated in various cell models. Bright mitochondria specific fluorescent signal in treated cells lasted several days without noticeable toxicity.General Significance
The probe AcQCy7 has been proofed to be a non-toxic agent for long-term mitochondria imaging. 相似文献17.
Carolyn M. Porteous Angela Logan Cameron Evans Elizabeth C. Ledgerwood David K. Menon Franklin Aigbirhio Robin A.J. Smith Michael P. Murphy 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Background
Mitochondrial dysfunction contributes to a range of pathologies, consequently there is a need to monitor mitochondrial function and to intervene pharmacologically to prevent mitochondrial damage. One approach to this is to deliver antioxidants, probes and pharmacophores to mitochondria by conjugation to the lipophilic triphenylphosphonium (TPP) cation that is taken up selectively by mitochondria driven by the membrane potential.Conclusions
Oral administration of TPP-conjugated antioxidants protects against mitochondrial damage in vivo. However, there is also a need to deliver molecules rapidly to mitochondria to respond quickly to pathologies and for the real-time assessment of mitochondrial function.Methods
To see if this was possible we investigated how rapidly TPP cations were taken up by mitochondria in vivo following intravenous (iv) administration.Results
AlkylTPP cations were accumulated selectively by mitochondria within mice within 5 min of iv injection. The extent of uptake was enhanced 10–30-fold relative to simple alkylTPP cations by attaching functional groups to the TPP cation via long, hydrophobic alkyl chains. Conclusions: Mitochondria-targeted antioxidants, probes and pharmacophores can be delivered into mitochondria within minutes of iv administration.General significance
These findings greatly extend the utility of mitochondria-targeted lipophilic cations as therapies and probes. 相似文献18.
Aim
Recent studies have emphasized the importance of the extracellular microenvironment in modulating cell growth, motility, and signalling. In this study we have evaluated the ability of a fibroblast derived-extracellular matrix (fd-ECM) to regulate type I collagen synthesis and degradation in fibroblasts.Main methods
Fibroblasts were plated on plastic (control) or on fd-ECM and type I collagen synthesis and degradation was evaluated. MTT, western blotting, real time PCR, zymographic analysis and inhibitor assays were utilised to investigate the molecular mechanism of type I collagen regulation by the fd-ECM.Key findings
Fibroblasts plated on fd-ECM showed significant downregulation in the production of type I collagen and COL1A2 messenger ribonucleic acid (mRNA) whilst COL1A1 mRNA remained unchanged. Cells grown on fd-ECM exhibited increased matrix metalloproteases (MMPs) and their corresponding mRNAs. The use of transforming growth factor β (TGF-β) and MMP inhibitors showed that the excess COL1A1 polypeptide chains were degraded by the combined action of MMP-1, MMP-2, MMP-9 and cathepsins.Significance
These results show the crucial role played by proteases in regulating extracellular matrix protein levels in the feedback regulation of connective tissue gene expression. 相似文献19.
Nicola Giangregorio Ferdinando Palmieri Cesare Indiveri 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
The mitochondrial carnitine/acylcarnitine carrier (CAC) is essential for cell metabolism since it catalyzes the transport of acylcarnitines into mitochondria allowing the β-oxidation of fatty acids. CAC functional and structural properties have been characterized. Cys residues which could form disulfides suggest the involvement of CAC in redox switches.Methods
The effect of GSH and GSSG on the [3H]-carnitine/carnitine antiport catalyzed by the CAC in proteoliposomes has been studied. The Cys residues involved in the redox switch have been identified by site-directed mutagenesis. Glutathionylated CAC has been assessed by glutathionyl-protein specific antibody.Results
GSH led to increase of transport activity of the CAC extracted from liver mitochondria. A similar effect was observed on the recombinant CAC. The presence of glutaredoxin-1 (Grx1) accelerated the GSH activation of the recombinant CAC. The effect was more evident at 37 °C. GSSG led to transport inhibition which was reversed by dithioerythritol (DTE). The effects of GSH and GSSG were studied on CAC Cys-mutants. CAC lacking C136 and C155 was insensitive to both reagents. Mutants containing these two Cys responded as the wild-type. Anti-glutathionyl antibody revealed the formation of glutathionylated CAC.Conclusions
CAC is redox-sensitive and it is regulated by the GSH/GSSG couple. C136 and C155 are responsible for the regulation which occurs through glutathionylation.General significance
CAC is sensitive to the redox state of the cell switching between oxidized and reduced forms in response to variation of GSSG and GSH concentrations. 相似文献20.