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1.
The uptake ofL-arginine into purified rat brain synaptosomes was investigated with respect to time and various concentrations ofL-[3H] arginine. Specific uptake was found to be linear with time for up to 5 min of incubation at 37°C. Electrolytes, including sodium chloride, potassium chloride, magnesium chloride and calcium chloride, inhibited uptake of 3 ML-arginine, and the inhibitory effect increased with increased electrolyte concentration under constant osmolarity. It was found thatL-arginine was transported into synaptosomes by two uptake components — a high affinity component (3.5 M) and a low affinity component (100 M). These two components were similar to the Ly+ system because of their extreme sensitivity to inhibition byL-lysine andL-ornithine but were distinguishable from each other by kinetic analysis of the uptake data and by their relative sensitivity to inhibition by several amino acids. 相似文献
2.
I. Campia E. Gazzano G. Pescarmona D. Ghigo A. Bosia C. Riganti 《Cellular and molecular life sciences : CMLS》2009,66(9):1580-1594
Digoxin and ouabain are steroid drugs that inhibit the Na+/K+-ATPase, and are widely used in the treatment of heart diseases. They may also have additional effects, such as on metabolism
of steroid hormones, although until now no evidence has been provided about the effects of these cardioactive glycosides on
the synthesis of cholesterol. Here we report that digoxin and ouabain increased the synthesis of cholesterol in human liver
HepG2 cells, enhancing the activity and the expression of the
3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), the rate-limiting enzyme of the cholesterol synthesis. This effect
was mediated by the binding of the sterol regulatory element binding protein-2 (SREBP-2) to the HMGCR promoter, and was lost
in cells silenced for SREBP-2 or loaded with increasing amounts of cholesterol. Digoxin and ouabain competed with cholesterol
for binding to the SREBP-cleavage-activating protein, and are critical regulators of cholesterol synthesis in human liver
cells.
Received 10 January 2009; received after revision 11 February 2009; accepted 6 March 2009 相似文献
3.
K. L. Sand E. Knudsen J. Rolin Y. Al-Falahi A. A. Maghazachi 《Cellular and molecular life sciences : CMLS》2009,66(8):1446-1456
Glatiramer acetate (GA or Copaxone) is a drug used to treat experimental autoimmune encephalomyelitis in mice and multiple
sclerosis in human. Here, we describe a new mechanism of action for this drug. GA enhanced the cytolysis of human NK cells
against autologous and allogeneic immature and mature monocyte-derived dendritic cells (DCs). This drug reduced the percentages
of mature DCs expressing CD80, CD83, HLA-DR or HLA-I. In contrast, it did not modulate the percentages of NK cells expressing
NKG2D, NKp30, or NKp44. Nonetheless, anti-NKp30 or anti-CD86 inhibited GA-enhanced human NK cell lysis of immature DCs. Hence,
CD86, and NKp30 are important for NK cell lysis of immature DCs, whereas CD80, CD83, HLA-DR and HLA-I are important for the
lysis of mature DCs when GA is used as a stimulus. Further, GA inhibited the release of IFN-γ 24 h but increased the release
of TNF-α 48 h after incubation with NK cells.
Received 13 November 2008; received after revision 10 February 2009; accepted 18 February 2009 相似文献
4.
Lan Chen Yan Wei Xueqing Wang Rongqiao He 《Cellular and molecular life sciences : CMLS》2009,66(15):2559-2571
Although the glycation of Tau that is involved in paired helical filament formation in Alzheimer’s disease has been widely
studied, little attention has been paid to the role of d-ribose in the glycation of Tau. Here, we show that Tau is rapidly glycated in the presence of d-ribose, resulting in oligomerization and polymerization. Glycated derivatives appeared after 24 h incubation. Western blotting
indicated the formation of advanced glycation end-products (AGEs) during initial stages of glycation. Thioflavin T-positive
(ThT-positive) aggregations that appeared from day 4 indicated the globular-like features. Atomic force microscopy revealed
that the surface morphology of ribosylated Tau40 was globular-like. Kinetic studies suggested that d-ribosylated Tau is slowly oligomerized and rapidly polymerized with ThT-positive features. Moreover, d-ribosylated Tau aggregates were highly toxic to SHSY5Y cells and resulted in both apoptosis and necrosis. This work has demonstrated
that d-ribose reacted with Tau protein rapidly, producing ThT-positive aggregations which had high cytotoxicity.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Vanhove M Zakhem M Devreese B Franceschini N Anne C Bebrone C Amicosante G Rossolini GM Van Beeumen J Frère JM Galleni M 《Cellular and molecular life sciences : CMLS》2003,60(11):2501-2509
The CphA metallo--lactamase produced by Aeromonas hydrophila exhibits two zinc-binding sites. Maximum activity is obtained upon binding of one zinc ion, whereas binding of the second zinc ion results in a drastic decrease in the hydrolytic activity. In this study, we analyzed the role of Asn116 and Cys221, two residues of the active site. These residues were replaced by site-directed mutagenesis and the different mutants were characterized. The C221S and C221A mutants were seriously impaired in their ability to bind the first, catalytic zinc ion and were nearly completely inactive, indicating a major role for Cys221 in the binding of the catalytic metal ion. By contrast, the binding of the second zinc ion was only slightly affected, at least for the C221S mutant. Mutation of Asn116 did not lead to a drastic decrease in the hydrolytic activity, indicating that this residue does not play a key role in the catalytic mechanism. However, the substitution of Asn116 by a Cys or His residue resulted in an approximately fivefold increase in the affinity for the second, inhibitory zinc ion. Together, these data suggested that the first zinc ion is located in the binding site involving the Cys221 and that the second zinc ion binds in the binding site involving Asn116 and, presumably, His118 and His196.Received 3 March 2003; received after revision 4 August 2003; accepted 25 August 2003 相似文献
6.
Interaction of galectin-1 with caveolae induces mouse embryonic stem cell proliferation through the Src, ERas, Akt and mTOR signaling pathways 总被引:1,自引:0,他引:1
M. Y. Lee S. H. Lee J. H. Park H. J. Han 《Cellular and molecular life sciences : CMLS》2009,66(8):1467-1478
Galectins have the potential to provide a promising alternative for unveiling the complexity of embryonic stem (ES) cell self-renewal,
although the mechanism by which galectins maintain ES cell self-renewal has yet to be identified. Galectin-1 increased [3H]-thymidine incorporation as well as cyclin expression and decreased p27kip1 expression. Src and caveolin-1 phosphorylation was increased by galectin-1, and phospho-caveolin-1 was inhibited by PP2.
In addition, inhibition of caveolin-1 by small interfering RNA and methyl-β-cyclodextrin (Mβ-CD) decreased galectin-1-induced
cyclin expression and [3H]-thymidine incorporation. Galectin-1 caused Akt and mTOR phosphorylation, which is involved in cyclin expression. Galectin-1-induced
phospho-Akt and -mTOR was inhibited by PP2, ERas siRNA, caveolin-1 siRNA and Mβ-CD. Furthermore, mTOR phosphorylation was
decreased by LY294002 and Akt inhibitor. Galectin-1-induced increase in cyclin expression and decrease in p27kip1 was blocked by Akt inhibitor and rapamycin. In conclusion, galectin-1 increased DNA synthesis in mouse ES cells via Src,
caveolin-1 Akt, and mTOR signaling pathways.
Received 30 October 2008; received after revision 18 February 2009; accepted 24 February 2009 相似文献
7.
R. J. S. Viana A. F. Nunes R. E. Castro R. M. Ramalho J. Meyerson S. Fossati J. Ghiso A. Rostagno C. M. P. Rodrigues 《Cellular and molecular life sciences : CMLS》2009,66(6):1094-1104
The vasculotropic E22Q mutant of the amyloid-β (Aβ) peptide is associated with hereditary cerebral hemorrhage with amyloidosis
Dutch type. The cellular mechanism(s) of toxicity and nature of the AβE22Q toxic assemblies are not completely understood.
Comparative assessment of structural parameters and cell death mechanisms elicited in primary human cerebral endothelial cells
by AβE22Q and wild-type Aβ revealed that only AβE22Q triggered the Bax mitochondrial pathway of apoptosis. AβE22Q neither
matched the fast oligomerization kinetics of Aβ42 nor reached its predominant β-sheet structure, achieving a modest degree
of oligomerization with a secondary structure that remained a mixture of β and random conformations. The endogenous molecule
tauroursodeoxycholic acid (TUDCA) was a strong modulator of AβE22Q-triggered apoptosis but did not significantly change the
secondary structures and fibrillogenic propensities of Aβ peptides. These data dissociate the pro-apoptotic properties of
Aβ peptides from their distinct mechanisms of aggregation/fibrillization in vitro, providing new perspectives for modulation of amyloid toxicity.
Received 20 November 2008; received after revision 12 December 2008; accepted 12 January 2009 相似文献
8.
Taylor DM Maxwell MM Luthi-Carter R Kazantsev AG 《Cellular and molecular life sciences : CMLS》2008,65(24):4000-4018
Sirtuins comprise a unique class of nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases that target multiple protein substrates to execute diverse biological functions. These enzymes are
key regulators of clinically important cellular and organismal processes, including metabolism, cell division and aging. The
desire to understand the important determinants of human health and lifespan has resulted in a firestorm of work on the seven
mammalian sirtuins in less than a decade. The implication of sirtuins in medically important areas such as diabetes, cancer,
cardiovascular dysfunction and neurodegenerative disease has further catapulted them to a prominent status as potential targets
for nutritional and therapeutic development. Here, we present a review of published results on sirtuin biology and its relevance
to human disease.
Received 25 June 2008; received after revision 20 August 2008; accepted 29 August 2008 相似文献
9.
R. P. Massengo-Tiassé J. E. Cronan 《Cellular and molecular life sciences : CMLS》2009,66(9):1507-1517
The enoyl-acyl carrier protein reductase (ENR) is the last enzyme in the fatty acid elongation cycle. Unlike most enzymes
in this essential pathway, ENR displays an unusual diversity among organisms. The growing interest in ENRs is mainly due to
the fact that a variety of both synthetic and natural antibacterial compounds are shown to specifically target their activity.
The primary anti-tuberculosis drug, isoniazid, and the broadly used antibacterial compound, triclosan, both target this enzyme.
In this review, we discuss the diversity of ENRs, and their inhibitors in the light of current research progress.
Received 3 November 2008; received after revision 5 December 2008; accepted 8 December 2008 相似文献
10.
11.
Structural biology of the purine biosynthetic pathway 总被引:1,自引:0,他引:1
Purine biosynthesis requires ten enzymatic transformations to generate inosine monophosphate. PurF, PurD, PurL, PurM, PurC,
and PurB are common to all pathways, while PurN or PurT, PurK/PurE-I or PurE-II, PurH or PurP, and PurJ or PurO catalyze the
same steps in different organisms. X-ray crystal structures are available for all 15 purine biosynthetic enzymes, including
7 ATP-dependent enzymes, 2 amidotransferases and 2 tetrahydrofolate-dependent enzymes. Here we summarize the structures of
the purine biosynthetic enzymes, discuss similarities and differences, and present arguments for pathway evolution. Four of
the ATP-dependent enzymes belong to the ATP-grasp superfamily and 2 to the PurM superfamily. The amidotransferases are unrelated,
with one utilizing an N-terminal nucleophileglutaminase and the other utilizing a triad glutaminase. Likewise the tetrahydrofolate-dependent
enzymes are unrelated. Ancestral proteins may have included a broad specificity enzyme instead of PurD, PurT, PurK, PurC,
and PurP, and a separate enzyme instead of PurM and PurL.
Received 26 May 2008; received after revision 30 June 2008; accepted 9 July 2008 相似文献
12.
S. M. Houten M. Chegary H. te Brinke W. J. Wijnen J. F. C. Glatz J. J. F. P. Luiken F. A. Wijburg R. J. A. Wanders 《Cellular and molecular life sciences : CMLS》2009,66(7):1283-1294
Organs are flexible as to which substrates they will use to maintain energy homeostasis. Under well-fed conditions, glucose
is a preferred substrate for oxidation. During fasting, fatty acid oxidation will become a more important energy source. Glucose
oxidation is decreased by fatty acids, a process in which the pyruvate dehydrogenase complex (PDH) and its regulator pyruvate
dehydrogenase kinase 4 (PDK4) play important roles. It is currently unknown how energy status influences PDH activity. We
show that AMP-activated protein kinase (AMPK) activation by hypoxia and AICAR treatment combined with fatty acid administration
synergistically induce PDK4 expression. We provide evidence that AMPK activation modulates ligand-dependent activation of
peroxisome proliferator-activated receptor. Finally, we show that this synergistic induction of PDK4 decreases cellular glucose
oxidation. In conclusion, AMPK and fatty acids play a direct role in fuel selection in response to cellular energy status
in order to spare glucose.
S. M. Houten, M. Chegary: These two authors contributed equally to this work.
Received 11 July 2008; received after revision 26 January 2009; accepted 02 February 2009 相似文献
13.
K. von Schwarzenberg S. A. E. Held A. Schaub K. M. Brauer A. Bringmann P. Brossart 《Cellular and molecular life sciences : CMLS》2009,66(7):1295-1308
In order to analyze the effects of peroxisome proliferator-activated receptor-γ (PPARγ) activation on renal cell carcinomas
we utilized several cell lines that were treated with the high affinity PPARγ agonist, troglitazone. Incubation of RCC cells
with troglitazone resulted in reduced secretion of growth factors that was due to the inhibition of MAP kinase signaling and
reduced nuclear localized expression of relB and HIF1alpha. Interestingly, the cell lines used showed a different sensitivity
towards apoptosis induction that did not correlate with the inhibition of growth factors or expression of pro- and antiapoptotic
molecules. To overcome this resistance the cells were treated with a combination of troglitazone and the proteasome inhibitor,
bortezomib. The combination of both compounds induced apoptosis even in cells resistant to both agents alone, due to increased
induction of ER-stress and caspase-3 mediated cell death.
Received 03 September 2009; received after revision 02 February 2009; accepted 10 February 2009 相似文献
14.
V. Le Fourn K. Gaplovska-Kysela B. Guhl R. Santimaria C. Zuber J. Roth 《Cellular and molecular life sciences : CMLS》2009,66(8):1434-1445
Little is known about the fate of machinery proteins of the protein quality control and endoplasmic reticulum(ER)-associated
degradation (ERAD). We investigated the degradation of the ERAD component EDEM1, which directs overexpressed misfolded glycoproteins
to degradation. Endogenous EDEM1 was studied since EDEM1 overexpression not only resulted in inappropriate occurrence throughout
the ER but also caused cytotoxic effects. Proteasome inhibitors had no effect on the clearance of endogenous EDEM1 in non-starved
cells. However, EDEM1 could be detected by immunocytochemistry in autophagosomes and biochemically in LC3 immuno-purified
autophagosomes. Furthermore, influencing the lysosome-autophagy pathway by vinblastine or pepstatin A/E64d and inhibiting
autophagosome formation by 3-methyladenine or ATGs short interfering RNA knockdown stabilized EDEM1. Autophagic degradation
involved removal of cytosolic Triton X-100-insoluble deglycosylated EDEM1, but not of EDEM1-containing ER cisternae. Our studies
demonstrate that endogenous EDEM1 in cells not stressed by the expression of a transgenic misfolded protein reaches the cytosol
and is degraded by basal autophagy.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Received 15 January 2009; received after revision 16 February 2009; accepted 17 February 2009
V. Le Fourn, K. Gaplovska-Kysela: These authors equally contributed to this work. 相似文献
15.
Poelarends GJ Veetil VP Whitman CP 《Cellular and molecular life sciences : CMLS》2008,65(22):3606-3618
Tautomerase superfamily members have an amino-terminal proline and a β–α–β fold, and include 4-oxalocrotonate tautomerase
(4-OT), 5-(carboxymethyl)-2-hydroxymuconate isomerase (CHMI), trans- and cis-3-chloroacrylic acid dehalogenase (CaaD and cis-CaaD, respectively), malonate semialdehyde decarboxylase (MSAD), and macrophage migration inhibitory factor (MIF), which
exhibits a phenylpyruvate tautomerase (PPT) activity. Pro-1 is a base (4-OT, CHMI, the PPT activity of MIF) or an acid (CaaD,
cis-CaaD, MSAD). Components of the catalytic machinery have been identified and mechanistic hypotheses formulated. Characterization
of new homologues shows that these mechanisms are incomplete. 4-OT, CaaD, cis-CaaD, and MSAD also have promiscuous activities with a hydratase activity in CaaD, cis-CaaD, and MSAD, PPT activity in CaaD and cis-CaaD, and CaaD and cis-CaaD activities in 4-OT. The shared promiscuous activities provide evidence for divergent evolution from a common ancestor,
give hints about mechanistic relationships, and implicate catalytic promiscuity in the emergence of new enzymes.
Received 22 May 2008; received after revision 20 June 2008; accepted 02 July 2008 相似文献
16.
Cardiolipin, the heart of mitochondrial metabolism 总被引:5,自引:0,他引:5
Cardiolipin is a unique phospholipid, which is almost exclusively localized in the mitochondrial inner membrane where it is
synthesized from phosphatidylglycerol and cytidinediphosphate-diacylglycerol. After primary synthesis, the mature acyl chain
composition of cardiolipin is achieved by at least two remodeling mechanisms. In the mitochondrial membrane cardiolipin plays
an important role in energy metabolism, mainly by providing stability for the individual enzymes and enzyme complexes involved
in energy production. Moreover, cardiolipin is involved in different stages of the mitochondrial apoptotic process and in
mitochondrial membrane dynamics. Cardiolipin alterations have been described in various pathological conditions. Patients
suffering from Barth syndrome have an altered cardiolipin homeostasis caused by a primary deficiency in cardiolipin remodeling.
Alterations in cardiolipin content or composition have also been reported in more frequent diseases such as diabetes and heart
failure. In this review we provide an overview of cardiolipin metabolism, function and its role in different pathological
states.
Received 16 January 2008; received after revision 26 February 2008; accepted 26 March 2008 相似文献
17.
F. Magherini A. Carpentieri A. Amoresano T. Gamberi C. De Filippo L. Rizzetto M. Biagini P. Pucci A. Modesti 《Cellular and molecular life sciences : CMLS》2009,66(5):933-947
In this study, a proteomic approach that combines selective labelling of proteins containing reduced cysteine residues with
two-dimensional electrophoresis/mass spectrometry was used to evaluate the redox state of protein cysteines during chronological
ageing in Saccharomyces cerevisiae. The procedure was developed on the grounds that biotinconjugated iodoacetamide (BIAM) specifically reacts with reduced cysteine
residues. BIAM-labelled proteins can then be selectively isolated by streptavidin affinity capture. We compared cells grown
on 2% glucose in the exponential phase and during chronological ageing and we found that many proteins undergo cysteine oxidation.
The target proteins include enzymes involved in glucose metabolism. Both caloric restriction and growth on glycerol resulted
in a decrease in the oxidative modification. Furthermore, in these conditions a reduced production of ROS and a more negative
glutathione half cell redox potential were observed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Received 15 September 2008; received after revision 17 December 2008; accepted 06 January 2009 相似文献
18.
S. Wilde E. Schlatter H. Koepsell B. Edemir S. Reuter H. Pavenstädt U. Neugebauer R. Schröter S. Brast G. Ciarimboli 《Cellular and molecular life sciences : CMLS》2009,66(10):1729-1740
In this work, regulation of organic cation transporter type 2 from rat (rOCT2) stably transfected in HEK293 cells was investigated
by microfluorimetry with 4-(4-(dimethylamino)styryl)-N-methylpyridinium as substrate. The transport mediated by rOCT2 was
specifically stimulated by PKA, phosphatidylinositol-3-kinase, p56lck tyrosine kinase, mitogen-extracellular-signal-regulated-kinase-1/2, calmodulin (CaM), and CaM-kinase-II. The regulatory pattern
of rOCT2 differs markedly quantitatively and qualitatively from that of other OCT isoforms. Only CaM-dependent upregulation
is conserved throughout the OCT family. For this reason, CaM regulation of rOCT2 was also investigated in isolated S3-segments
(known to express only rOCT2) of male and female rat proximal tubules. Inhibition of CaM by calmidazolium significantly decreased
rOCT2 activity (−49.0 ± 13.6%, n = 4) in male but not female (9.0 ± 13.0%, n = 4) rats. Real-time PCR and Western blot investigations
of CaM expression in rat kidneys showed that male animals have significantly higher CaM expression. This is the first study
describing post-translational gender-dependent rOCT2 regulation.
Received 26 February 2009; accepted 16 March 2009 相似文献
19.
A. Deshmukh F. Salehzadeh S. Metayer-Coustard R. Fahlman K. S. Nair L. Al-Khalili 《Cellular and molecular life sciences : CMLS》2009,66(8):1457-1466
Excessive nutrients, especially amino acids, impair insulin action on glucose metabolism in skeletal muscle. We tested the
hypothesis that the branched-chain amino acid leucine reduces acute insulin action in primary myotubes via a negative feedback mechanism involving ribosomal protein S6 kinase 1 (S6K1). The effect of S6K1 on glucose metabolism was
determined by applying RNA interference (siRNA). Leucine (5 mM) reduced glucose uptake and incorporation to glycogen by 13%
and 22%, respectively, compared to the scramble siRNA-transfected control at the basal level. Leucine also reduced insulin-stimulated
Akt phosphorylation, glucose uptake and glucose incorporation to glycogen (39%, 39% and 37%, respectively), and this reduction
was restored after S6K1 silencing. Depletion of S6K1 enhanced basal glucose utilization and protected against the development
of impaired insulin action, in response to excessive leucine. In conclusion, S6K1 plays an important role in the regulation
of insulin action on glucose metabolism in skeletal muscle.
Received 22 December 2008; received after revision 19 February 2009; accepted 23 February 2009 相似文献
20.
C. Gordon-Thomson A. Kumari L. Tomkins P. Holford J. T. Djordjevic L. C. Wright T. C. Sorrell G. P. M. Moore 《Cellular and molecular life sciences : CMLS》2009,66(6):1116-1125
Chitotriosidase secreted by activated human macrophages has been implicated in the defence against chitin-bearing pathogens.
The antifungal properties of human chitotriosidase were investigated here following retroviral vector-mediated gene transfer
of the open reading frame of the chitotriosidase gene into Chinese hamster ovary cells. A chitinase assay confirmed that the
engineered cells secreted recombinant chitotriosidase constitutively. Two dimensional gel electrophoresis and western blotting
indicated that the recombinant protein is the major, chitin-binding, fifty kilodalton isoform. Culture medium conditioned
by the transduced cells inhibited growth of isolates of Aspergillus niger, Candida albicans and Cryptococcus neoformans. Furthermore, longevity was significantly increased in a mouse model of cryptococcosis when cells transduced with the chitotriosidase
gene and encapsulated in alginate microspheres were implanted subcutaneously in the animals. Engraftment of microcapsules
containing cells transduced with the chitotriosidase gene has the potential to combat infections caused by chitinous pathogens
through the prolonged delivery of recombinant chitotriosidase.
Received 29 November 2008; received after revision 11 January 2009; accepted 13 January 2009 相似文献