共查询到20条相似文献,搜索用时 859 毫秒
1.
Yvonne G. J. van Helden Roger W. L. Godschalk Hans J. M. Swarts Peter C. H. Hollman Frederik J. van Schooten Jaap Keijer 《Cellular and molecular life sciences : CMLS》2011,68(3):489-504
Molecular mechanisms triggered by high dietary beta-carotene (BC) intake in lung are largely unknown. We performed microarray
gene expression analysis on lung tissue of BC supplemented beta-carotene 15,15′-monooxygenase 1 knockout (Bcmo1
−/−) mice, which are—like humans—able to accumulate BC. Our main observation was that the genes were regulated in an opposite direction in male and female Bcmo1
−/− mice by BC. The steroid biosynthetic pathway was overrepresented in BC-supplemented male Bcmo1
−/− mice. Testosterone levels were higher after BC supplementation only in Bcmo1
−/− mice, which had, unlike wild-type (Bcmo1
+/+) mice, large variations. We hypothesize that BC possibly affects hormone synthesis or metabolism. Since sex hormones influence
lung cancer risk, these data might contribute to an explanation for the previously found increased lung cancer risk after
BC supplementation (ATBC and CARET studies). Moreover, effects of BC may depend on the presence of frequent human BCMO1 polymorphisms, since these effects were not found in wild-type mice. 相似文献
2.
Diversity of Cl− Channels 总被引:5,自引:0,他引:5
Cl− channels are widely found anion pores that are regulated by a variety of signals and that play various roles. On the basis
of molecular biologic findings, ligand-gated Cl− channels in synapses, cystic fibrosis transmembrane conductors (CFTRs) and ClC channel types have been established, followed
by bestrophin and possibly by tweety, which encode Ca2+-activated Cl− channels. The ClC family has been shown to possess a variety of functions, including stabilization of membrane potential,
excitation, cellvolume regulation, fluid transport, protein degradation in endosomal vesicles and possibly cell growth. The
molecular structure of Cl− channel types varies from 1 to 12 transmembrane segments. By means of computer-based prediction, functional Cl− channels have been synthesized artificially, revealing that many possible ion pores are hidden in channel, transporter or
unidentified hydrophobic membrane proteins. Thus, novel Cl−-conducting pores may be occasionally discovered, and evidence from molecular biologic studies will clarify their physiologic
and pathophysiologic roles.
Received 28 July 2005; received after revision 25 August 2005; accepted 21 September 2005 相似文献
3.
Catherine Aude-Garcia Christian Villiers Serge M. Candéias Catherine Garrel Caroline Bertrand Véronique Collin Patrice N. Marche Evelyne Jouvin-Marche 《Cellular and molecular life sciences : CMLS》2011,68(4):687-696
The cellular prion glycoprotein (PrPC) is ubiquitously expressed but its physiologic functions remain enigmatic, particularly in the immune system. Here, we demonstrate
in vitro and in vivo that PrPC is involved in T lymphocytes response to oxidative stress. By monitoring the intracellular level of reduced glutathione,
we show that PrP−/− thymocytes display a higher susceptibility to H2O2 exposure than PrP+/+ cells. Furthermore, we find that in mice fed with a restricted diet, a regimen known to increase the intracellular level
of ROS, PrP−/− thymocytes are more sensitive to oxidative stress. PrPC function appears to be specific for oxidative stress, since no significant differences are observed between PrP−/− and PrP+/+ mice exposed to other kinds of stress. We also show a marked evolution of the redox status of T cells throughout differentiation
in the thymus. Taken together, our results clearly ascribe to PrPC a protective function in thymocytes against oxidative stress. 相似文献
4.
Lucas Matt Stylianos Michalakis Franz Hofmann Verena Hammelmann Andreas Ludwig Martin Biel Thomas Kleppisch 《Cellular and molecular life sciences : CMLS》2011,68(1):125-137
Neuronal hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are known to modulate spontaneous activity, resting
membrane potential, input resistance, afterpotential, rebound activity, and dendritic integration. To evaluate the role of
HCN2 for hippocampal synaptic plasticity, we recorded long-term potentiation (LTP) in the direct perforant path (PP) to CA1
pyramidal cells. LTP was enhanced in mice carrying a global deletion of the channel (HCN2−/−) but not in a pyramidal neuron-restricted knockout. This precludes an influence of HCN2 located in postsynaptic pyramidal
neurons. Additionally, the selective HCN blocker zatebradine reduced the activity of oriens-lacunosum moleculare interneurons
in wild-type but not HCN2−/− mice and decreased the frequency of spontaneous inhibitory currents in postsynaptic CA1 pyramidal cells. Finally, we found
amplified LTP in the PP of mice carrying an interneuron-specific deletion of HCN2. We conclude that HCN2 channels in inhibitory
interneurons modulate synaptic plasticity in the PP by facilitating the GABAergic output onto pyramidal neurons. 相似文献
5.
J. -P. Bargetzi 《Cellular and molecular life sciences : CMLS》1958,14(12):445-447
Summary Two closely related forms ofCoregonus from Lake Neuchatel were examined cytologically and biochemically, in order to ascertain the chromosome number and the DNA
content of haploid and diploid nuclei.Coregonus fera has 2N=78 ± 2 chromosomes, and a DNA content (diploid) of 5.8 × 10−9 mg;Coregonus macrophthalmus, 2N=78+ ± 3, DNA content of 6.1 × 10−9 mg. The difference between the two DNA constants is statistically significant. These results do not support the hypothesis
which postulates that polyploidy may be a determining factor in the speciation of these fishes.
相似文献
6.
M. F. Shi J. Jiao W. G. Lu F. Ye D. Ma Q. G. Dong X. Xie 《Cellular and molecular life sciences : CMLS》2010,67(22):3915-3925
Cancer stem cells (CSCs) play an important role in the development, invasion, and drug resistance of carcinoma, but the exact
phenotype and characteristics of ovarian CSCs are still disputable. In this study, we identified cancer stem cell-like cells
(CSC-LCs) and investigated their characteristics from the ovarian adenocarcinoma cell line 3AO. Our results showed that CSC-LCs
were enriched in sphere-forming test and highly expressed CD44+CD24−. The spheres and CD24− cells possessed strong tumorigenic ability by transplantation into nonobese diabetic/severe combined immunodeficient mice.
CD44+CD24− cells expressed stem cell markers and differentiated to CD44+CD24+ cells by immunofluorescence assay and fluorescence-activated cell-sorting analysis. In vitro experiments verified that CD44+CD24− cells were markedly resistant to carboplatin and paclitaxol. In conclusion, our study identifies the CD44+CD24− phenotype, self-renewal, high tumorigenicity, differentiation potential, and drug resistance of ovarian CSC-LCs. Our findings
may provide the evidence needed to explore a new strategy in the treatment of ovarian cancer. 相似文献
7.
Porcelli AM Ghelli A Mastrocola T Rugolo M 《Cellular and molecular life sciences : CMLS》1999,56(1-2):167-173
The Ca2+ ionophore ionomycin induced cytosolic [Ca2+]i elevation as well as strong activation of Cl− efflux in mouse mammary epithelial cell lines expressing wild-type or mutated (deletion of phenylalaline 508) cystic fibrosis
transmembrane conductance regulator (CFTR) or vector. Ionomycin-induced Cl− efflux was abolished by the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid, whereas both activators and inhibitors of phospholipase A2 had no effect, indicating the involvement of Ca2+-dependent Cl- channels. Stimulation of arachidonic acid release by ionomycin and phorbol ester was not significantly different between
wild-type or mutated cell lines, whereas vector-transfected cells exhibited a significant higher release, which was shown
to be due to larger amount of immunoreactive cytosolic phospholipase A2. These results indicate that phospholipase A2 activity of C127 cells was not influenced by the presence of wild-type or mutated CFTR.
Received 27 April 1999; received after revision 11 June 1999; accepted 23 July 1999 相似文献
8.
δ-Protocadherins constitute a group of cadherins characterized by several conserved motifs in their cytoplasmic domains. We
present a phylogenetic analysis that further divides this group into δ1-protocadherins (comprising protocadherin-1, −7, −9
and −11 or -X/Y) and δ2-protocadherins (comprising protocadherin-8, −10, −17, −18 and −19). The δ-protocadherin genes, which
are located on different chromosomes in man and mouse, have a similar gene structure. They are expressed as multiple splice
forms, differing mostly in their cytoplasmic domains. Some δ-protocadherins were reported to mediate weak cell-cell adhesion
in vitro and cell sorting in vivo. In addition, individual δ-protocadherins might play important roles in signaling pathways,
as they bind to proteins such as TAF1/Set, protein phosphatase-1α and the Frizzled 7 receptor. The spatiotemporally restricted
expression of δ-protocadherins in different tissues and species and the results of their functional analysis, mainly in Xenopus, suggest that they play multiple, tightly regulated roles in vertebrate development.
Received 18 July 2005; received after revision 26 August 2005; accepted 2 September 2005 相似文献
9.
Yuk-Man Leung Kar-Lok Wong Chia-Huei Lin Chia-Chia Chao Chun-Hsiao Chou Li-Yun Chang Siao-Wei Chen Tzu-Hurng Cheng Yueh-Hsiung Kuo 《Cellular and molecular life sciences : CMLS》2010,67(1):147-156
Voltage-gated K+ (Kv) channels exhibit slow or C-type inactivation during continuous depolarization. A selective pharmacological agent targeting
C-type inactivation is hitherto lacking. Here, we report that 6β-acetoxy-7α-hydroxyroyleanone (AHR), a diterpenoid compound
isolated from Taiwania cryptomerioides, can selectively modify C-type inactivation of Kv1.2 channels. Extracellular, but not intracellular, AHR (50 μM) dramatically
accelerated the slow decay of Kv currents and left-shifted the steady-state inactivation curve. AHR blocked Kv currents with
an IC50 of 17.7 μM. AHR did not affect the kinetics and voltage-dependence of Kv1.2 channel activation. Channel block by AHR was
independent of intracellular K+ concentration. In addition, effect of AHR was much attenuated in a Kv1.2 V370G mutant defective in C-type inactivation. Therefore,
block of Kv1.2 channels by AHR did not appear to involve direct occlusion of the outer pore but depended on C-type inactivation.
AHR could thus be a probe targeting Kv channel C-type inactivation gate. 相似文献
10.
Cancer cell metabolism is characterized by limited oxidative phosphorylation in order to minimize oxidative stress. We have
previously shown that the flavonoid flavone in HT-29 colon cancer cells increases the uptake of pyruvate or lactate into mitochondria,
which is followed by an increase in O2−.. production that finally leads to apoptosis. Similarly, a supply of palmitoylcarnitine in combination with carnitine induces
apoptosis in HT-29 cells by increasing the mitochondrial respiration rate. Here we show that flavone-induced apoptosis is
increased more than twofold in the presence of palmitoylcarnitine due to increased mitochondrial fatty acid transport and
the subsequent metabolic generation of O2−. in mitochondria is the initiating factor for the execution of apoptosis.
Received 12 August 2005; received after revision 12 October 2005; accepted 14 October 2005 相似文献
11.
12.
R.E. Williamson J.E. Burn C.H. Hocart 《Cellular and molecular life sciences : CMLS》2001,58(10):1475-1490
Cellulose microfibrils containing crystalline β-1,4-glucan provide the major structural framework in higher-plant cell walls. Genetic analyses of Arabidopsis thaliana now link specific genes to plant cellulose production just as was achieved some years earlier with bacteria. Cellulose-deficient
mutants have defects in several members of one family within a complex glycosyltransferase superfamily and in one member of
a small family of membrane-bound endo-1,4-β-glucanases. The mutants also accumulate a readily extractable β-1,4-glucan that has short chains which, in at least one case, are lipid linked. Cellulose could be made by direct extension
of the glucan chain by the glycosyltransferase or, as the mutant suggests, by an indirect route which makes lipid-linked oligosaccharides.
Models discussed incorporate the known enzymes and lipo-glucan and raise the possibility that different CesA glycosyltransferases
may catalyse different steps.
Received 5 January 2001; received after revision 25 April 2001; accepted 25 April 2001 相似文献
13.
Laitinen OH Hytönen VP Nordlund HR Kulomaa MS 《Cellular and molecular life sciences : CMLS》2006,63(24):2992-3017
Chicken avidin and bacterial streptavidin, (strept)avidin, are proteins widely utilized in a number of applications in life
science, ranging from purification and labeling techniques to diagnostics, and from targeted drug delivery to nanotechnology.
(Strept)avidin-biotin technology relies on the extremely tight and specific affinity between (strept)avidin and biotin (dissociation
constant, Kd≈10−14–10−16 M). (Strept)avidins are also exceptionally stable proteins. To study their ligand binding and stability characteristics,
the two proteins have been extensively modified both chemically and genetically. There are excellent accounts of this technology
and chemically modified (strept)avidins, but no comprehensive reviews exist concerning genetically engineered (strept)avidins.
To fill this gap, we here go through the genetically engineered (strept)avidins, summarizing how these constructs were designed
and how they have improved our understanding of the structural and functional characteristics of these proteins, and the benefits
they have provided for (strept)avidin-biotin technology.
Received 22 June 2006; received after revision 1 August 2006; accepted 21 September 2006 相似文献
14.
Werner Kuhn 《Cellular and molecular life sciences : CMLS》1957,13(8):301-307
Summary The time requirement is treated for a longitudinal fission by Brownian movement of a very long particle consisting of two
or more filaments twisted a great number of times round each other to form a double spiral. It is shown that a comparatively
swift disintegration is obtained by partial rotation or torsion round the axis of the spiral, resulting in a loosing of the
spiral structure and subsequent separation of the constituents by translational Brownian movement. The time required to separate
a double spiral consisting of about 900 turns of a height of 3.4 × 10−7 cm and a radius of 10−7 cm, thus having a length of 3 × 10−4 cm being realized approximately by deoxyribonucleic acid is found by this mechanism to be about 50 to 80 s. The time required
to undo the same spiral by unwrapping it turn by turn would be about 150 days. The result of the considerations is related
to observations published byAlexander andSteacy on deoxyribonucleic acid. An additional remark stresses the importance of stereochemical asymmetry for the practicability
of the mechanism and therefore the importance of optical activity for the time requirement of such disintegrations or transformations
of high polymer material occurring in living organisms.
相似文献
15.
According to the widely acknowledged mitochondrial free radical theory of aging (MFRTA), the macromolecular damage that results
from the production of toxic reactive oxygen species (ROS) during cellular respiration is the cause of aging. However, although
it is clear that oxidative damage increases during aging, the fundamental question regarding whether mitochondrial oxidative
stress is in any way causal to the aging process remains unresolved. An increasing number of studies on long-lived vertebrate
species, mutants and transgenic animals have seriously challenged the pervasive MFRTA. Here, we describe some of these new
results, including those pertaining to the phenotype of the long-lived Mclk1
+/−
mice, which appear irreconcilable with the MFRTA. Thus, we believe that it is reasonable to now consider the MFRTA as refuted
and that it is time to use the insight gained by many years of testing this theory to develop new views as to the physiological
causes of aging. 相似文献
16.
Simon S. Gerber Sofia Lejon Michael Locher Johann Schaller 《Cellular and molecular life sciences : CMLS》2010,67(9):1505-1518
The human α2-plasmin inhibitor (A2PI) possesses unique N- and C-terminal extensions that significantly influence its biological activities.
The C-terminal segment, A2PIC (Asn398-Lys452), contains six lysines thought to be involved in the binding to lysine-binding sites in the kringle domains of human plasminogen,
of which four (Lys422, Lys429, Lys436, Lys452) are completely and two (Lys406, Lys415) are partially conserved. Multiple Lys to Ala mutants of A2PIC were expressed in Escherichia coli and used in intrinsic fluorescence titrations with kringle domains K1, K4, K4 + 5, and K1 + 2 + 3 of human plasminogen. We
were able to identify the C-terminal Lys452 as the main binding partner in recombinant A2PIC (rA2PIC) constructs with isolated kringles. We could show a cooperative,
zipper-like enhancement of the interaction between C-terminal Lys452 and internal Lys436 of rA2PIC and isolated K1 + 2 + 3, whereas the other internal lysine residues contribute only to a minor extent to the binding
process. Sulfated Tyr445 in the unique C-terminal segment revealed no influence on the binding affinity to kringle domains. 相似文献
17.
Résumé Le système neuromusculaire dansElectrophorus electricus est étudié avec des électrodes intracellulaires. La transmission neuromusculaire est supprimée avec D-tubocurarine (5 · 10–7
p/v) ou avec un excès des ions Mg++ (12 mM) dans la solution. 相似文献
18.
19.
Kim DS Jeong YM Moon SI Kim SY Kwon SB Park ES Youn SW Park KC 《Cellular and molecular life sciences : CMLS》2006,63(22):2661-2668
Indole-3-carbinol (I3C) has been found to act against several types of cancer, while ultraviolet B (UVB) is known to induce
the apoptosis of human melanoma cells. Here, we investigated whether I3C can sensitize G361 human melanoma cells to UVB-induced
apoptosis. We examined the effects of combined I3C and UVB (I3C/UVB) at various dosages. I3C (200 μM)/UVB (50 mJ/cm2) synergistically reduced melanoma cell viability, whereas I3C (200 μM) or UVB (50 mJ/cm2), separately, had little effect on cell viability. DNA fragmentation assays indicated that I3C/UVB induced apoptosis. Further
results show that I3C/UVB activates caspase-8, −3, and Bid and causes the cleavage of poly(ADP-ribose) polymerase. Moreover,
I3C decreased the expression of the anti-apoptotic protein, Bcl-2, whereas UVB increased the translocation of Bax to mitochondria.
Thus, an increased Bax/Bcl-2 ratio by I3C/UVB may result in melanoma apoptosis. In conclusion, our study demonstrated that
I3C sensitizes human melanoma cells by down-regulating Bcl-2.
Received 5 July 2006; received after revision 25 August 2006; accepted 11 September 2006 相似文献
20.
Inoue K 《Cellular and molecular life sciences : CMLS》2008,65(19):3074-3080
Accumulating findings indicate that nucleotides play an important role in microglia through P2 purinoceptors. P2 purinoceptors
are divided into two families, ionotropic receptors (P2X) and metabotropic receptors (P2Y). P2X receptors (7 types; P2X1 – P2X7) contain intrinsic pores that open by binding with ATP. P2Y receptors (8 types; P2Y1, 2, 4, 6, 11, 12, 13 and 14) are activated by nucleotides and couple to intracellular second-messenger systems through heteromeric G-proteins. Nucleotides
are released or leaked from non-excitable cells as well as neurons in physiological and pathophysiological conditions. Microglia
express many types of P2 purinoceptors and are known as resident macrophages in the CNS. ATP and other nucleotides work as
‘warning molecules’ especially through activating microglia in pathophysiological conditions. Microglia play a key role in
neuropathic pain, chemotaxis and phagocytosis through nucleotide-evoked activation of P2X4, P2Y12 and P2Y6 receptors, respectively. These findings indicate that extracellular nucleotides are important players in the central stage
of microglial function.
Received 19 April 2008; received after revision 20 May 2008; accepted 23 May 2008 相似文献