共查询到20条相似文献,搜索用时 109 毫秒
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Yoshida Y Obita T Kokusho Y Ohmura T Katayama T Ueda T Imoto T 《Cellular and molecular life sciences : CMLS》2003,60(9):1998-2008
DnaA protein binds specifically to a 9-base- pair motif called the DnaA box. Domain IV comprises 94 amino acid residues and is required for DNA binding. Using nuclear magnetic resonance analysis, we investigated the interaction between DnaA domain IV and both a DnaA box and a non-specific oligonucleotide that has a reduced affinity for DnaA. The 1H-15N HSQC spectrum of DnaA domain IV showed prominent chemical shift perturbations on six residues (Arg399, Ala404, Leu422, Asp433, Thr435 and Thr436) in the presence of the DnaA box. Through homology modeling, we located all of these residues on one side surface of the DnaA domain IV molecule. Moreover, we compared the chemical shift perturbation of the 1H-15N HSQC spectrum in the presence of the DnaA box with that in the presence of a non-specific oligonucleotide, and the results suggested that Leu422 imparts specificity in binding with the DnaA box.Received 6 May 2003; received after revision 18 June 2002; accepted 4 July 2003 相似文献
3.
Kris Meerschaert Moe Phyu Tun Eline Remue Ariane De Ganck Ciska Boucherie Berlinda Vanloo Gisèle Degeest Joël Vandekerckhove Pascale Zimmermann Nitin Bhardwaj Hui Lu Wonhwa Cho Jan Gettemans 《Cellular and molecular life sciences : CMLS》2009,66(24):3951-3966
Zonula occludens proteins (ZO) are postsynaptic density protein-95 discs large-zonula occludens (PDZ) domain-containing proteins that play a fundamental role in the assembly of tight junctions and establishment of cell polarity. Here, we show that the second PDZ domain of ZO-1 and ZO-2 binds phosphoinositides (PtdInsP) and we identified critical residues involved in the interaction. Furthermore, peptide and PtdInsP binding of ZO PDZ2 domains are mutually exclusive. Although lipid binding does not seem to be required for plasma membrane localisation of ZO-1, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P 2) binding to the PDZ2 domain of ZO-2 regulates ZO-2 recruitment to nuclear speckles. Knockdown of ZO-2 expression disrupts speckle morphology, indicating that ZO-2 might play an active role in formation and stabilisation of these subnuclear structures. This study shows for the first time that ZO isoforms bind PtdInsPs and offers an alternative regulatory mechanism for the formation and stabilisation of protein complexes in the nucleus. 相似文献
4.
Induction of vanadium accumulation and nuclear sequestration causing cell suicide in human Chang liver cells 总被引:1,自引:0,他引:1
K. H. Sit R. Paramanantham B. H. Bay K. P. Wong P. Thong F. Watt 《Cellular and molecular life sciences : CMLS》1996,52(8):778-785
Very little is known about the modulation of vanadium accumulation in cells, although this ultratrace element has long been seen as an essential nutrient in lower life forms, but not necessarily in humans where factors modulating cellular uptake of vanadium seem unclear. Using nuclear microscopy, which is capable of the direct evaluation of free and bound (total) elemental concentrations of single cells we show here that an NH4Cl acidification prepulse causes distinctive accumulation of vanadium (free and bound) in human Chang liver cells, concentrating particularly in the nucleus. Vanadium loaded with acidification but leaked away with realkalinization, suggests proton-dependent loading. Vanadyl(4), the oxidative state of intracellular vanadium ions, is known to be a potent source of hydroxyl free radicals (OH.). The high oxidative state of nuclei after induction of vanadyl(4) loading was shown by the redox indicator methylene blue, suggesting direct oxidative damage to nuclear DNA. Flow cytometric evaluation of cell cycle phase-specific DNA composition showed degradation of both 2N and 4N DNA phases in G1, S and G2/M cell cycle profiles to a solitary 1N DNA peak, in a dose-dependent manner, effective from micromolar vanadyl(4) levels. This trend was reproduced with microccocal nuclease digestion in a time response, supporting the notion of DNA fragmentation effects. Several other approaches confirmed fragmentation occurring in virtually all cells after 4 mM V(4) loading. Ultrastructural profiles showed various stages of autophagic autodigestion and well defined plasma membrane outlines, consistent with programmed cell death but not with necrotic cell death. Direct intranuclear oxidative damage seemed associated with the induction of mass suicide in these human Chang liver cells following vanadium loading and nuclear sequestration. 相似文献
5.
Recent advances in androgen receptor action 总被引:17,自引:0,他引:17
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The intracellular signaling pathways mediating the nuclear exclusion of the androgen receptor (AR) by melatonin were evaluated
in PC3 cells stably transfected with the AR. The melatonin-induced nuclear exclusion of the AR by melatonin (100 nM, 3 h)
was blocked by LY 83583 (an inhibitor of guanylyl cyclases). 8-Bromo-cGMP (a cell-permeable cGMP analog), mimicked the effect
of melatonin, as did ionomycin (a calcium ionophore) and PMA [an activator of protein kinase C (PKC)], and their effects were
blocked by GF-109203X (a selective PKC inhibitor). BAPTA (an intracellular calcium chelator) blocked the effects of melatonin
and 8-bromo-cGMP but not of PMA. Inhibition or activation of the protein kinase A pathway did not affect basal or melatonin-mediated
AR localization. We conclude that the melatonin-mediated rise in cGMP elicits AR nuclear exclusion via a pathway involving
increased intracellular calcium and PKC activation. These results define a novel signaling pathway that regulates AR localization
and androgen responses in target cells.
Received 31 July 2001; received after revision 18 September 2001; accepted 30 October 2001 相似文献
8.
Izaurralde E 《Cellular and molecular life sciences : CMLS》2001,58(8):1105-1112
The distinguishing feature of eukaryotic cells is the segregation of RNA biogenesis and DNA replication in the nucleus, separate
from the cytoplasmic machinery for protein synthesis. As a consequence, messenger RNAs (mRNAs) and all cytoplasmic RNAs from
nuclear origin need to be transported from their site of synthesis in the nucleus to their final cytoplasmic destination.
Nuclear export occurs through nuclear pore complexes (NPCs) and is mediated by saturable transport receptors, which shuttle
between the nucleus and cytoplasm. The past years have seen great progress in the characterization of the mRNA export pathway
and the identification of proteins involved in this process. A novel family of nuclear export receptors (the NXF family),
distinct from the well-characterized family of importin β-like proteins, has been implicated in the export of mRNA to the cytoplasm.
Received 23 January 2001; received after revision 12 April 2001; accepted 12 April 2001 相似文献
9.
Huiyu Low Chun Song Chua Tiow-Suan Sim 《Cellular and molecular life sciences : CMLS》2009,66(18):3081-3090
A mitogen-activated protein kinase (MAPK), Pfmap2, has been identified in Plasmodium falciparum. However, its bona fide activator remains elusive as no MAPK kinase (MAPKK) homologues have been found so far. Instead, Pfnek3,
a NIMA (never in mitosis, Aspergillus)-related kinase, was earlier reported to display a MAPKK-like activity due to its activating effect on Pfmap2. In this study,
the regulatory mechanism of Pfnek3 was investigated. Pfnek3 was found to possess a SSEQSS motif within its activation loop
that fulfills the consensus SXXXS/T phospho-activating sequence of MAPKKs. Functional analyses of the SSEQSS motif by site-directed
mutagenesis revealed that phosphorylation of residues S221 and S226 is essential for mediating Pfnek3 activity. Moreover,
via tandem mass-spectrometry, residue T82 was uncovered as an additional phosphorylation site involved in Pfnek3 activation.
Collectively, these results provide valuable insights into the potential in vivo regulation of Pfnek3, with residues T82,
S221 and S226 functioning as phospho-activating sites. 相似文献
10.
Antoni Camins Javier G. Pizarro Daniel Alvira Javier Gutierrez-Cuesta Aurelio Vazquez de la Torre Jaume Folch Francesc X. Sureda Ester Verdaguer Felix Junyent Joaquín Jordán Isidre Ferrer Mercè Pallàs 《Cellular and molecular life sciences : CMLS》2010,67(22):3865-3882
In the present study we demonstrated that neurotoxin MPP+-induced DNA damage is followed by ataxia telangiectasia muted (ATM) activation either in cerebellar granule cells (CGC) or in B65 cell line. In CGC, the selective ATM inhibitor KU-55933 showed neuroprotective effects against MPP+-induced neuronal cell loss and apoptosis, lending support to the key role of ATM in experimental models of Parkinson’s disease. Likewise, we showed that knockdown of ATM levels in neuroblastoma B65 cells using an ATM-specific siRNA attenuates the phosphorylation of retinoblastoma protein without affecting other cell-cycle proteins involved in the G0/G1 cell-cycle phase. Moreover, we demonstrated DNA damage, in human brain samples of PD patients. These findings support a model in which MPP+ leads to ATM activation with a subsequent DNA damage response and activation of pRb. Therefore, this study demonstrates a new link between DNA damage by MPP+ and cell-cycle re-entry through retinoblastoma protein phosphorylation. 相似文献
11.
Gineitis A Treigyte G Savickiene J Shanbhag VP Stigbrand T 《Cellular and molecular life sciences : CMLS》1999,55(2):317-326
The two-dimensional electrophoretic patterns of nuclear proteins and their tyrosine phosphorylation were compared for HL-60
cells before and after differentiation induction to granulocytes by dimethyl sulfoxide, all-trans retinoic acid and N
6,O
2-dibutyryl adenosine 3′5′-cyclic monophosphate. Regardless of the inducer used, some nuclear proteins, which are tyrosine-phosphorylated
in proliferating HL-60 cells, undergo gradual dephosphorylation 12–72 h after induction of differentiation, followed by drastic
dephosphorylation during maturation to granulocytes. At least 13 nuclear proteins with a molecular mass of 35–110 kDa are
dephosphorylated, and 6 nuclear proteins undergo tyrosine phosphorylation. Analysis of the nuclear proteins differentially
extracted by salt and detergents indicates that changes in their tyrosine phosphorylation during the maturation stage of differentiating
granulocytes occur mainly in proteins which are abundant in nucleoplasm, chromatin and residual nuclear structures. The abundance
of these proteins, residing in the nuclear structures, and their long-term modification in phosphorylation during the maturation
stages of differentiation strongly suggest that tyrosine phosphorylation of these proteins is involved in reorganization of
the differentiating cell nucleus.
Received 21 September 1998; received after revision 24 November 1998; accepted 3 December 1998 相似文献
12.
Sánchez-Margalet V González-Yanes C Santos-Alvarez J Najib S 《Cellular and molecular life sciences : CMLS》1999,55(1):142-147
Insulin action is initiated by binding to its cognate receptor, which then triggers multiple cellular responses by activating
different signaling pathways. There is evidence that insulin receptor signaling may involve G protein activation in different
target cells. We have studied the activation of G proteins in rat hepatoma (HTC) cells. We found that insulin stimulated binding
of guanosine 5′-O-(3-thiotriphosphate) (GTP-γ-35S) to plasma membrane proteins of HTC cells, in a dose-dependent manner. This effect was completely blocked by pertussis toxin
treatment of the membranes, suggesting the involvement of G proteins of the Gα
i/Gα
o family. The expression of these Gα proteins was checked by Western blotting. Next, we used blocking antibodies to sort out the specific Gα protein activated by insulin stimulation. Anti-Gα
il,2 antibodies completely prevented insulin-stimulated GTP binding, whereas anti-Gα
o,i3 did not modify this effect of insulin on GTP binding. Moreover, we found physical association of the insulin receptor with
Gα
i1,2 by copurification studies. These results further support the involvement of a pertussis toxin-sensitive G protein in insulin
receptor signaling and provides some evidence of specific association and activation of Gα
i1,2 protein by insulin. These findings suggest that Gα
i1,2 proteins might be involved in insulin action.
Received 23 September 1998; received after revision 23 November 1998; accepted 25 November 1998 相似文献
13.
Important to the function of calpains is temporal and spatial regulation of their proteolytic activity. Here, we demonstrate
that cytoplasm-resident calpain 2 cleaves human nuclear topoisomerase I (hTOP1) via Ca2+-activated proteolysis and nucleoplasmic shuttling of proteases. This proteolysis of hTOP1 was induced by either ionomycin-caused
Ca2+ influx or addition of Ca2+ in cellular extracts. Ca2+ failed to induce hTOP1 proteolysis in calpain 2-knockdown cells. Moreover, calpain 2 cleaved hTOP1 in vitro. Furthermore,
calpain 2 entered the nucleus upon Ca2+ influx, and calpastatin interfered with this process. Calpain 2 cleavage sites were mapped at K158 and K183 of hTOP1. Calpain 2-truncated hTOP1 exhibited greater relaxation activity but remained able to interact with nucleolin and
to form cleavable complexes. Interestingly, calpain 2 appears to be involved in ionomycin-induced protection from camptothecin-induced
cytotoxicity. Thus, our data suggest that nucleocytoplasmic shuttling may serve as a novel type of regulation for calpain
2-mediated nuclear proteolysis. 相似文献
14.
Senchou V Weide R Carrasco A Bouyssou H Pont-Lezica R Govers F Canut H 《Cellular and molecular life sciences : CMLS》2004,61(4):502-509
The RGD tripeptide sequence, a cell adhesion motif present in several extracellular matrix proteins of mammalians, is involved in numerous plant processes. In plant-pathogen interactions, the RGD motif is believed to reduce plant defence responses by disrupting adhesions between the cell wall and plasma membrane. Photoaffinity cross-linking of [125I]-azido-RGD heptapeptide in the presence of purified plasma membrane vesicles of Arabidopsis thaliana led to label incorporation into a single protein with an apparent molecular mass of 80 kDa. Incorporation could be prevented by excess RGD peptides, but also by the IPI-O protein, an RGD-containing protein secreted by the oomycete plant pathogen Phytophthora infestans. Hydrophobic cluster analysis revealed that the RGD motif of IPI-O (positions 53–56) is readily accessible for interactions. Single amino acid mutations in the RGD motif in IPI-O (of Asp56 into Glu or Ala) resulted in the loss of protection of the 80-kDa protein from labelling. Thus, the interaction between the two proteins is mediated through RGD recognition and the 80-kDa RGD-binding protein has the characteristics of a receptor for IPI-O. The IPI-O protein also disrupted cell wall-plasma membrane adhesions in plasmolysed A. thaliana cells, whereas IPI-O proteins mutated in the RGD motif (D56A and D56E) did not.Received 23 October 2003; received after revision 5 December 2003; accepted 12 December 2003 相似文献
15.
Summary Studies have implicated Ca++ in the actions of ethanol at many biochemical levels. Calcium as a major intracellular messenger in the central nervous system is involved in many processes, including protein phosphorylation enzyme activation and secretion of hormones and neurotransmitters. The control of intracellular calcium, therefore, represents a major step by which neuronal cells regulate their activities. The present review focuses on three primary areas which influence intracellular calcium levels; voltage-dependent Ca++ channels, receptor-mediated inositol phospholipid hydrolysis, and Ca++/Mg++-ATPase, the high affinity membrane Ca++ pump.Current research suggests that a subtype of the voltage-dependent Ca++ channel, the dihydropyridine-sensitive Ca++ channel, is uniquely sensitive to acute and chronic ethanol treatment. Acute exposure inhibits, while chronic ethanol exposure increases45Ca++-influx and [3H]dihydropyridine receptor binding sites. In addition, acute and chronic exposure to ethanol inhibits, then increases Ca++/Mg++-ATPase activity in neuronal membranes. Changes in Ca++ channel and Ca++/Mg++-ATPase activity following chronic ethanol may occur as an adaptation process to increase Ca++ availability for intracellular processes. Since receptor-dependent inositol phospholipid hydrolysis is enhanced after chronic ethanol treatment, subsequent activation of protein kinase-C may also be involved in the adaptation process and may indicate increased coupling for receptor-dependent changes in Ca++/Mg++-ATPase activity.The increased sensitivity of three Ca++-dependent processes suggest that adaptation to chronic ethanol exposure may involve coupling of one or more of these processes to receptor-mediated events. 相似文献
16.
S. Batra 《Cellular and molecular life sciences : CMLS》1986,42(6):608-611
Summary Specific binding of tritiated quinuclidinyl benzilate (3H-QNB) to surface membrane muscarinic receptors was utilized to identify plasma membrane (PM) fractions from smooth muscle of the rabbit urinary bladder. Accumulation of3H-QNB in the PM fraction was 4–5-fold higher than that in fractions of endoplasmic reticulum (EM) or mitochondria (M). A similar pattern of 相似文献
17.
Manuela Ambrosio Francesca Fanelli Silvia Brocchetti Francesco Raimondi Mario Mauri G. Enrico Rovati Valérie Capra 《Cellular and molecular life sciences : CMLS》2010,67(17):2979-2989
In class A GPCRs the E/DRY motif is critical for receptor activation and function. According to experimental and computational
data, R3.50 forms a double salt bridge with the adjacent E/D3.49 and E/D6.30 in helix 6, constraining the receptor in an inactive
state. The disruption of this network of interactions facilitates conformational transitions that generate a signal or constitutive
activity. Here we demonstrate that non-conservative substitution of either E129(3.49) or E240(6.30) of thromboxane prostanoid receptor (TP) resulted in mutants characterized by agonist-induced more efficient signaling properties,
regardless of the G protein coupling. Results of computational modeling suggested a more effective interaction between Gq and the agonist-bound forms of the TP mutants, compared to the wild type. Yet, none of the mutants examined revealed any
increase in basal activity, precluding their classification as constitutively active mutants. Here, we propose that these
alternative active conformations might be identified as superactive mutants or SAM. 相似文献
18.
Blenn C Wyrsch P Bader J Bollhalder M Althaus FR 《Cellular and molecular life sciences : CMLS》2011,68(8):1455-1466
Oxidative DNA damage to cells activates poly(ADP-ribose)polymerase-1 (PARP-1) and the poly(ADP-ribose) formed is rapidly degraded
to ADP-ribose by poly(ADP-ribose)glycohydrolase (PARG). Here we show that PARP-1 and PARG control extracellular Ca2+ fluxes through melastatin-like transient receptor potential 2 channels (TRPM2) in a cell death signaling pathway. TRPM2 activation
accounts for essentially the entire Ca2+ influx into the cytosol, activating caspases and causing the translocation of apoptosis inducing factor (AIF) from the inner
mitochondrial membrane to the nucleus followed by cell death. Abrogation of PARP-1 or PARG function disrupts these signals
and reduces cell death. ADP-ribose-loading of cells induces Ca2+ fluxes in the absence of oxidative damage, suggesting that ADP-ribose is the key metabolite of the PARP-1/PARG system regulating
TRPM2. We conclude that PARP-1/PARG control a cell death signal pathway that operates between five different cell compartments
and communicates via three types of chemical messengers: a nucleotide, a cation, and proteins. 相似文献
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Camille Faure Mariana Ramos Jean-Antoine Girault 《Cellular and molecular life sciences : CMLS》2013,70(1):137-152
Cytonuclear signaling is essential for long-term alterations of cellular properties. Several pathways involving regulated nuclear accumulation of Ser/Thr kinases have been described but little is known about cytonuclear trafficking of tyrosine kinases. Proline-rich tyrosine kinase 2 (Pyk2) is a cytoplasmic non-receptor tyrosine kinase enriched in neurons and involved in functions ranging from synaptic plasticity to bone resorption, as well as in cancer. We previously showed the Ca2+-induced, calcineurin-dependent, nuclear localization of Pyk2. Here, we characterize the molecular mechanisms of Pyk2 cytonuclear localization in transfected PC12 cells. The 700–841 linker region of Pyk2 recapitulates its depolarization-induced nuclear accumulation. This region includes a nuclear export motif regulated by phosphorylation at residue S778, a substrate of cAMP-dependent protein kinase and calcineurin. Nuclear import is controlled by a previously identified sequence in the N-terminal domain and by a novel nuclear targeting signal in the linker region. Regulation of cytonuclear trafficking is independent of Pyk2 activity. The region regulating nuclear localization is absent from the non-neuronal shorter splice isoform of Pyk2. Our results elucidate the mechanisms of Ca2+-induced nuclear accumulation of Pyk2. They also suggest that Pyk2 nuclear accumulation is a novel type of signaling response that may contribute to specific long-term adaptations in neurons. 相似文献