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921.
922.
NELIN, a new F-actin associated protein, stimulates HeLa cell migration and adhesion 总被引:1,自引:0,他引:1
Wang W Zhang W Han Y Chen J Wang Y Zhang Z Hui R 《Biochemical and biophysical research communications》2005,330(4):1127-1131
A new gene (GenBank Accession No. AF114264) was cloned from umbilical vein wall tissue by using RT-PCR. The gene shares high similarity to the gene encoding F-actin binding protein nexilin, so named as NELIN. A clone of 2737bp contains open reading frame of 1344bp extending from 412 to 1755. NELIN was expressed primarily in the heart and skeletal muscle among eight tested normal tissues. Immunofluorescence and immunoprecipitation demonstrated that NELIN product was associated with F-actin. Stable transfection of NELIN into HeLa cells increased the cell migration by 2.17-fold and the adhesion by 1.67-fold, respectively, compared to cells with the empty vector (P<0.05). The results support that NELIN product is an F-actin associated protein and mediates cell motility. 相似文献
923.
One of the major problems in the treatment of human cancer is the phenomenon of drug resistance. Increased glutathione (gamma-glutamylcysteinylglycine, GSH) conjugation (inactivation) due to elevated level of cytosolic glutathione S-transferase (GST) is believed to be an important mechanism in tumor cell resistance. However, the potential involvement of microsomal GST in the establishment of acquired drug resistance (ADR) remains uncertain. In our experiments, a combination of liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) was employed for structural characterization of the resulting conjugates between GSH and melphalan, one of the alkylating agents. The spontaneous reaction of 1mM melphalan with 5mM GSH at 37 degrees C in aqueous phosphate buffer for 1h gave primarily the monoglutathionyl and diglutathionyl melphalan derivatives, with small amounts of mono- and dihydroxy melphalan derivatives. We demonstrated that rat liver microsomal GST presented a strong catalytic effect on the reaction as determined by the increase of monoglutathionyl and diglutathionyl melphalan derivatives and the decrease of melphalan. We showed that microsomal GST was activated by melphalan in a concentration- and time-dependent manner. Microsomal GST which was stimulated approximately 1.5-fold with melphalan had a stronger catalytic effect. Thus microsomal GST may play a potential role in the metabolism of melphalan in biological membranes, and in the development of ADR. 相似文献
924.
Receptor-ligand bonds that mediate cell adhesion are often subjected to forces that regulate their dissociation via modulating off-rates. Off-rates control how long receptor-ligand bonds last and how much force they withstand. One should therefore be able to determine off-rates from either bond lifetime or unbinding force measurements. However, substantial discrepancies exist between the force dependence of off-rates derived from the two types of measurements even for the same interactions, e.g., selectins dissociating from their ligands, which mediate the tethering and rolling of leukocytes on vascular surfaces during inflammation and immune surveillance. We used atomic force microscopy to measure survival times of P-selectin dissociating from P-selectin glycoprotein ligand 1 or from an antibody in both bond lifetime and unbinding force experiments. By a new method of data analysis, we showed that the discrepancies resulted from the assumption that off-rates were functions of force only. The off-rates derived from forced dissociation data depended not only on force but also on the history of force application. This finding provides a new paradigm for understanding how force regulates receptor-ligand interactions. 相似文献
925.
Zhou J Zhu P Jiang JL Zhang Q Wu ZB Yao XY Tang H Lu N Yang Y Chen ZN 《BMC cell biology》2005,6(1):25
Background
During infection and inflammation, circulating blood monocytes migrate from the intravascular compartments to the extravascular compartments, where they mature into tissue macrophages. The maturation process prepares the cells to actively participate in the inflammatory and immune responses, and many factors have been reported to be involved in the process. We found in our study that CD147 played a very important role in this process. 相似文献926.
Liu Z Sha Y Huang T Yang B Duan GL 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2005,828(1-2):2-8
A sensitive and reliable high-performance liquid chromatographic method was developed for the determination of vertilmicin in rat plasma. Derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by C(18) reversed-phase chromatography allowed the fluorimetric detection of vertilmicin. Optimal conditions for the derivatization of vertilmicin are described. The limit of quantification was 0.02 mg/L. The pharmacokinetics of vertilmicin was studied in 24 rats following intramuscular injection (i.m.) of different doses (4, 8, 16, 32 mg/kg of body weight). The pharmacokinetic parameter values were estimated by use of 3P97 program. In this study, we assessed the dose proportionality of vertilmicin after single intramuscular injection doses and obtained new information on the pharmacokinetics of the compound. 相似文献
927.
Zhao L Huang C Shan Z Xiang B Mei L 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2005,821(1):67-74
High-performance liquid chromatography (HPLC) was developed for fingerprint analysis of Psoralea corylifolia. Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MSn) technique was first employed to identify the components of the fingerprint. The samples were separated with an Alltima C18 column (250 mm x 4.6 mm, 5 microm) by linear gradient elution using water-acetic acid (A; 100:0.1, v/v) and acetonitrile (B; 0 min, 40%; 15 min, 50%; 35 min, 60%; 45 min, 70%; 55 min, 80%; and maintained for 5 min) as mobile phase at a flow rate of 1.0 ml/min and detector wavelength at 245 nm. A standard procedure was developed for HPLC fingerprint analysis. Average chromatogram of 10 batches of P. corylifolia L. from Sichuan and Henan Provinces, PR China, which has been considered as the original and genuine herbal medicine for a long time, was first established as the characteristic fingerprint. There are 12 common peaks in this fingerprint. Ten of these common peaks were identified by MS data. This profile was then used to identify and assess the differences among the herb grown in various areas of China. The HPLC fingerprint analysis is specific and may serve for quality identification and comprehensive evaluation of P. corylifolia. 相似文献
928.
Molecular cloning and functional analysis of ESGP, an embryonic stem cell and germ cell specific protein 总被引:2,自引:0,他引:2
Several putative Oct-4 downstream genes from mouse embryonic stem (ES) cells have been identified using the suppression-subtractive hybridization method. In this study, one of the novel genes encoding an ES cell and germ cell specific protein (ESGP) was cloned by rapid amplification of cDNA ends. ESGP contains 801 bp encoding an 84 amino acid small protein and has no significant homology to any known genes. There is a signal peptide at the N-terminal of ESGP protein as predicted by SeqWeb (GCG) (SeqWeb version 2 ttp://gcg.biosino.org:8080/). The result of immunofluorescence assay suggested that ESGP might encode a secretory protein. The expression pattern of ESGP is consistent with the expression of Oct-4 during embryonic development. ESGP protein was detected in fertilized oocyte, from 3.5 day postcoital (dpc) blastocyst to 17.5 dpc embryo, and was only detected in testis and ovary tissues in adult. In vitro, ESGP was only expressed in pluripotent cell lines, such as embryonic stem cells, embryonic carcinoma cells and embryonic germ cells, but not in their differentiated progenies. Despite its specific expression, forced expression of ESGP is not indispensable for the effect of Oct-4 on ES cell self-renewal, and does not affect the differentiation to three germ layers. 相似文献
929.
A very promising approach to understanding the mechanism of protein thermostability is to investigate the structure-function relationship of homologous proteins with different thermostabilities. Ribosome recycling factor (RRF), which is an essential factor for protein synthesis in bacteria, may be a good candidate for such study. In this report, a ribosome recycling factor from Thermoanaerobacter tengcongensis was expressed and characterized. This protein contains 184 residues, shows 51.4% identity to that of Escherichia coli RRF, and has very strong antigenic cross-reactivity with antibody to E. coli RRF. In vivo activity assay shows that weak residual activity may remain in TteRRF in E. coli cells. Circular dichroism spectral analysis shows that TteRRF has a very similar secondary structure to that of E. coli RRF, implying that they have similar tertiary structures. However, their thermostabilities are significantly different. To find which domain of RRF is mainly responsible for maintaining stability, TteDI/EcoDII and EcoDI/TteDII RRF chimeras were created. Their domain I and domain II are from E. coli and T. tengcongensis RRFs, respectively. The results of GdnHCl and heat induced denaturation of the chimeric RRFs suggest that the domain I plays a major role in maintaining the stability of the RRF molecule. 相似文献
930.
Jiang ZY Zhou QL Holik J Patel S Leszyk J Coleman K Chouinard M Czech MP 《The Journal of biological chemistry》2005,280(22):21622-21628
Insulin signaling through protein kinase Akt/protein kinase B (PKB), a downstream element of the phosphatidylinositol 3-kinase (PI3K) pathway, regulates diverse cellular functions including metabolic pathways, apoptosis, mitogenesis, and membrane trafficking. To identify Akt/PKB substrates that mediate these effects, we used antibodies that recognize phosphopeptide sites containing the Akt/PKB substrate motif (RXRXX(p)S/T) to immunoprecipitate proteins from insulin-stimulated adipocytes. Tryptic peptides from a 250-kDa immunoprecipitated protein were identified as the protein kinase WNK1 (with no lysine) by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, consistent with a recent report that WNK1 is phosphorylated on Thr60 in response to insulin-like growth factor I. Insulin treatment of 3T3-L1 adipocytes stimulated WNK1 phosphorylation, as detected by immunoprecipitation with antibody against WNK1 followed by immunoblotting with the anti-phosphoAkt substrate antibody. WNK1 phosphorylation induced by insulin was unaffected by rapamycin, an inhibitor of p70 S6 kinase pathway but abolished by the PI3K inhibitor wortmannin. RNA interference-directed depletion of Akt1/PKB alpha and Akt2/PKB beta attenuated insulin-stimulated WNK1 phosphorylation, but depletion of protein kinase C lambda did not. Whereas small interfering RNA-induced loss of WNK1 protein did not significantly affect insulin-stimulated glucose transport in 3T3-L1 adipocytes, it significantly enhanced insulin-stimulated thymidine incorporation by about 2-fold. Furthermore, depletion of WNK1 promoted serum-stimulated cell proliferation of 3T3-L1 preadipocytes, as evidenced by a 36% increase in cell number after 48 h in culture. These data suggest that WNK1 is a physiologically relevant target of insulin signaling through PI3K and Akt/PKB and functions as a negative regulator of insulin-stimulated mitogenesis. 相似文献