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991.
Acconcia F Ascenzi P Fabozzi G Visca P Marino M 《Biochemical and biophysical research communications》2004,316(3):878-883
17beta-Estradiol (E2)-induced rapid functions (from seconds to minutes) can be attributed to a fraction of nuclear estrogen receptor-alpha (ERalpha) localized at the plasma membrane. As a potential mechanism, we postulated that S-palmitoylation of the Cys447 residue may explain the ability of ERalpha to associate to plasma membrane making possible E2-dependent rapid functions [e.g., extracellular regulated kinase (ERK) activation]. Here, we report direct evidence that the mutation of the Cys447 residue to Ala impairs human ERalpha palmitoylation and E2-induced rapid ERK phosphorylation when transfected in ER-devoid HeLa cells. Moreover, the Cys447Ala mutation significantly decreases the E2-induced transactivation of an estrogen responsive element construct probe. Similar effects were obtained treating HeLa cells transfected with wild type ERalpha with the palmitoyl-acyltransferase inhibitor 2-bromo-hexadecanoic acid. Moreover, the deletion of the A-D domains (containing the DNA binding region) of ERalpha had no consequences on [(3)H]palmitate incorporation, whereas no palmitoylation occurred in the ERalpha mutant devoid of the E domain (i.e., ligand binding domain). These results point to the pivotal role of the Cys447 residue in ERalpha palmitoylation and in the modulation of E2-induced non-genomic functions. 相似文献
992.
Carrozzo R Rizza T Stringaro A Pierini R Mormone E Santorelli FM Malorni W Matarrese P 《Journal of neurochemistry》2004,90(2):490-501
The key role of mitochondria in the apoptotic process is well understood, but not many data are available regarding the specific role of mitochondrial DNA mutations in determining cell fate. We investigated whether two mitochondrial DNA mutations (L217R and L156R) associated with maternally-inherited Leigh syndrome may play a specific role in triggering the apoptotic cascade. Considering that different nuclear genetic factors may influence the expression of mtDNA mutations, we used a 143BTK(-) osteosarcoma cell line deprived from its own mtDNA in order to insert mutated mtDNAs. Analysis of mitochondrial features in these cybrids indicated that both mitochondrial DNA mutations produced evidence of biochemical, functional and ultrastructural modifications of mitochondria, and that these modifications were associated with an increased apoptotic proneness. Cybrids were highly susceptible to two different apoptotic stimuli, tumour necrosis factor-alpha and Staurosporin. The mechanism involved was the mitochondrial 'intrinsic' pathway, i.e. the caspase 9-driven cascade. More importantly, our results also indicated that the polarization state of the mitochondrial membrane, i.e. a constitutive hyperpolarization detected in cybrid clones, played a specific role. Interestingly, the different effects of the two mutations in terms of susceptibility to apoptosis probably reflect the deeper bioenergetic defect associated with the L217R mutation. This work provides the first evidence that hyperpolarization of mitochondria may be a 'risk factor' for cells with a deep ATPase dysfunction, such as cells from patients with maternally-inherited Leigh syndrome. 相似文献
993.
Human immunodeficiency virus type 1 gp120 induces abnormal maturation and functional alterations of dendritic cells: a novel mechanism for AIDS pathogenesis 总被引:8,自引:0,他引:8
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Dendritic cells (DCs) play a crucial role in bridging innate and acquired immune responses to pathogens. In human immunodeficiency virus type 1 (HIV-1) infection, immature DCs (iDCs) are also main targets for HIV-1 at the mucosal level. In this study, we evaluated the effects of HIV-1-DC interactions on the maturation and functional activity of these cells. Exposure of human monocyte-derived iDCs to either aldrithiol-2-inactivated HIV-1 or gp120 led to an upmodulation of activation markers indicative of functional maturation. Despite their phenotype, these cells retained antigen uptake capacity and showed an impaired ability to secrete cytokines or chemokines and to induce T-cell proliferation. Although gp120 did not interfere with DC differentiation, the capacity of these cells to produce interleukin-12 (IL-12) upon maturation was markedly reduced. Likewise, iDCs stimulated by classical maturation factors in the presence of gp120 lacked allostimulatory capacity and did not produce IL-12, in spite of their phenotype typical of activated DCs. Exogenous addition of IL-12 restores the allostimulatory capacity of gp120-exposed DCs. The finding that gp120 induces abnormal maturation of DCs linked to profound suppression of their activities unravels a novel mechanism by which HIV can lead to immune dysfunction in AIDS patients. 相似文献
994.
Persichetti P Di Lella F Delfino S Scuderi N 《Plastic and reconstructive surgery》2004,113(1):373-8; discussion 379-80
Many authors have indicated the presence of ectopic or accessory upper eyelid fat pads, but the effective rate of eyelid fat variations and the corresponding clinical features are still unclear. The purpose of this study was to evaluate the variability of upper lid fat and to define the anatomical landmarks of the adipose pockets of the upper lid. From January of 1998 to January of 2002, the authors investigated the upper eyelid fat compartments of 47 patients who underwent upper blepharoplasty. To support surgical findings, 11 fresh cadavers were also investigated; the anatomy of the intraorbital fat and of the upper eyelid fat compartments was reviewed. Ten patients (21.3 percent) showed an accessory fat pad in the upper lid, which was found on both sides in nine cases. In all patients, the third fat pad was situated lateral to the two classic compartments described by Castanares, behind the orbital septum. Surgical dissections demonstrated that this fat pad derived from the preaponeurotic fat. Anatomical dissections in three cadavers demonstrated an accessory fat compartment protruding under the inferior border of the lacrimal gland. This protruding fat derived from the preaponeurotic fat in all cases and might justify the clinical appearance of a bulge or fullness in the lateral third of the upper eyelid. In the authors' experience, the presence of an accessory upper eyelid fat pad was a frequent finding during blepharoplasty; it could be found and actually resected in about 21 percent of all cases. Surgical and experimental findings put this element as a lateral physiological extension of the preaponeurotic fat that can anteriorly protrude under the inferior border of the lacrimal gland toward the orbital septum. The clinical appearance may be a bulge or fullness in the upper eyelid, and its resection can better define the lateral one third of the supratarsal fold. 相似文献
995.
996.
Aggregation kinetics of bovine serum albumin studied by FTIR spectroscopy and light scattering 总被引:5,自引:0,他引:5
Militello V Casarino C Emanuele A Giostra A Pullara F Leone M 《Biophysical chemistry》2004,107(2):175-187
To investigate which type of structural and conformational changes is involved in the aggregation processes of bovine serum albumin (BSA), we have performed thermal aggregation kinetics in D(2)O solutions of this protein. The tertiary conformational changes are followed by Amide II band, the secondary structural changes and the formation of beta-aggregates by the Amide I' band and, finally, the hydrodynamic radius of aggregates by dynamic light scattering. The results show, as a function of pD, that: tertiary conformational changes are more rapid as pD increases; the aggregation proceeds through formation of ordered aggregates (oligomers) at pD far from the isoelectric point of the protein; disordered structures add as the pD decreases. Moreover, beta-aggregates seem to contribute only to oligomers formation, as showed by the good correlation between kinetics of scattering intensity and IR absorption intensity. These results indicate for BSA a general mechanism of aggregation composed by partial unfolding of the tertiary structure and by the decrease of alpha-helix and random coil contents in favor of beta-sheet aggregates. This mechanism strictly depends on pD and gives rise to almost two distinct types of macromolecular aggregates. 相似文献
997.
998.
The flavanone naringenin (Nar), especially abundant in the Mediterranean diet, is reported to have anti-proliferative effects in many cancer cell lines. Antioxidant activities, kinase and glucose uptake inhibition have been proposed as molecular mechanisms for these effects. In addition, an anti-estrogenic activity has been observed but, at the present, it is poorly understood whether this latter activity could play a role in the Nar anti-tumoral effects. Here, we tested the ability of Nar to activate a specific, rapid signal transduction pathway committed to the generation of an apoptotic cascade in the presence of one of the two estrogen receptor (ER) isoforms (i.e., ERalpha or ERbeta). Cancer cells containing transfected (human cervix epitheloid carcinoma HeLa cells) or endogenous ERalpha (human hepatoma HepG2 cells) or ERbeta (human colon adenocarcinoma DLD-1 cells) were used. Our results show that Nar exerts an anti-proliferative effect only in the presence of ERalpha or ERbeta. Moreover, Nar stimulation induces the activation of p38/MAPK leading to the pro-apoptotic caspase-3 activation and to the poly(ADP-ribose) polymerase cleavage in all cancer cell lines considered. Notably, Nar shows an anti-estrogenic effect only in ERalpha containing cells; whereas in ERbeta containing cells, Nar mimics the 17beta-estradiol effects. These findings indicate new steps in the mechanism underlying ER-dependent anti-proliferative effects of Nar suggesting new potential chemopreventive actions of flavonoids on cancer growth. 相似文献
999.
Integration of anteroposterior and dorsoventral regulation of Phox2b transcription in cranial motoneuron progenitors by homeodomain proteins 总被引:4,自引:0,他引:4
Samad OA Geisen MJ Caronia G Varlet I Zappavigna V Ericson J Goridis C Rijli FM 《Development (Cambridge, England)》2004,131(16):4071-4083
Little is known about the molecular mechanisms that integrate anteroposterior (AP) and dorsoventral (DV) positional information in neural progenitors that specify distinct neuronal types within the vertebrate neural tube. We have previously shown that in ventral rhombomere (r)4 of Hoxb1 and Hoxb2 mutant mouse embryos, Phox2b expression is not properly maintained in the visceral motoneuron progenitor domain (pMNv), resulting in a switch to serotonergic fate. Here, we show that Phox2b is a direct target of Hoxb1 and Hoxb2. We found a highly conserved Phox2b proximal enhancer that mediates rhombomere-restricted expression and contains separate Pbx-Hox (PH) and Prep/Meis (P/M) binding sites. We further show that both the PH and P/M sites are essential for Hox-Pbx-Prep ternary complex formation and regulation of the Phox2b enhancer activity in ventral r4. Moreover, the DV factor Nkx2.2 enhances Hox-mediated transactivation via a derepression mechanism. Finally, we show that induction of ectopic Phox2b-expressing visceral motoneurons in the chick hindbrain requires the combined activities of Hox and Nkx2 homeodomain proteins. This study takes an important first step to understand how activators and repressors, induced along the AP and DV axes in response to signaling pathways, interact to regulate specific target gene promoters, leading to neuronal fate specification in the appropriate developmental context. 相似文献
1000.
Modica M Romeo G Materia L Russo F Cagnotto A Mennini T Gáspár R Falkay G Fülöp F 《Bioorganic & medicinal chemistry》2004,12(14):3891-3901
This work reports on the synthesis and affinities for the 5-HT(3) versus the 5-HT(4) receptor of new piperazinyl-substituted thienopyrimidine derivatives 20-45 with a view to identify potent and selective ligands for the 5-HT(3) receptor. Some of the new compounds show good affinity for the 5-HT(3) receptor and, notably, do not display any affinity for the 5-HT(4) receptor. 4-(4-Methyl-1-piperazinyl)-2-methylthio-6,7-dihydro-5H-cyclopenta[4,5]thieno[2,3-d]pyrimidine 31 exhibits the highest affinity for the 5-HT(3) receptor (Ki = 33 nM) and behaves as noncompetitive antagonist. 相似文献