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Objective To construct an eukaryotic expression vector pEGFP-N1-CKB and establish a stably transfected NCI-H520 cell line.Methods Human CKB gene was amplified by PCR with human CKB cDNA library as the template and the fragment was combined with plasmid pEGFP-N1.The recombinant expression vector,pEGFP-N1-CKB,was transfected to NCI-H520 using Lipofectamin.The stably transfected cell line was established after G418 selection and the expression level of CKB gene before and after transfection was detected by Western blot.Results After identification by restriction enzyme digestion and sequencing,the eukaryotic expression vector,pEGFP-N1-CKB,was successfully constructed.The expression level of CKB in NCI-H520 transfected by pEGFP-N1-CKB was significantly higher than that in control.CKB gene had a stable transfection in NCI-H520 cells.Conclusions An eukaryotic plasmid encoding CKB (pEGFP-N1-CKB) has been constructed and a cell line expressed CKB stably has been successfully prepared.
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Objective In order to investigate the effect of SH2B1 on leptin signal transduction JAK2/IRS2 and its biological function.Methods Vitro kinase assay and Western blot were used to analyse tyrosine phosphorylatin of key molecule JAK2 and insulin receptor substrate-2 (IRS2). ELISA was used to measure the plasma leptin levels in mice. The postnatal growth of mice was monitored over 27 weeks. Results SH2B1 dramatically enhanced the leptin-stimulated tyrosine phosphorylation of JAK2 and IRS2 in HEK293 cells stably expressing LRb (HEK239~(LRb)). Leptin-stimulated activation of hypothalamic JAK2 and phosphorylation of hyphothalamic IRS2 were significantly impaired in SH2B1~(-/-) mice. The deletion of SH2B1 led to leptin resistance,and fasting and randomly fed plasma leptin levels were respectively 3.2 times and 5.1 times higher in SH2B1~(-/-) males than wild-type littermates at 15 weeks of age. SH2B1~(-/-) males gained body weight rapidly and exceeded wild-type littermates from 5~(th) week. SH2B1(-/-) (at 21 weeks) was approximately twice heavier than wild-type littermates.Conclusion SH2B1 is an endogenous enhancer of leptin sensitivity and required for maintaining normal bodyweight in mice via leptin JAK2/IRS2 pathway.
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The molecular techniques were used to analyse tyrosine phosphorylation of JAK2 and STAT3 in leptin receptor overpression cell lines and SH2-Bβ knockout (SH2-Bβ-/-) mice. The serum level of leptin in SH2-Bβ mice was measured by ELISA. The results showed that SH2-Bβ dramatically enhanced the leptin-stimulated tyrosine phosphorylation of JAK2 and STAT3 in vitro. Leptin-stimulated activation of JAK2 and phosphorylation of STAT3 were significantly impaired in hypothalamus of SH2-Bβ-/- mice. The fasting and postprandial serum levels of leptin and body weight were markedly increased in SH2-Bβ-/- mice. Therefore, SH2-Bβ is an endogenous enhancer of leptin sensitivity and regulates body weight via leptin/ JAK2/STAT3 pathway.
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Objective To investigate cholecystokinin (CCK),carbachol, and vasoactive intestinal peptide(VIP)stimulating peptide chain elongation in mouse pancreatic acini in vitro and its molecular mechanism. Methods ~3H-lecucine incorporation assay was used to measure the basal and secretagogues-stimulated pancreatic acini elongation rates. Western blot was applied to analyse the effect of phosphorylation of the elongation factor 2 (eEF2) and the eEF2 kinase. MEK inhibitor (PD98059), SAPK/p38 inhibitor (SB202190), and mTOR inhibitor (rapamycin) were used to respectively block MEK, SAPK/p38, and mTOR intracellular pathways or the phosphatase inhibitor (calyculin A) pretreatment before CCK treatment. Results All secretagogues except VIP increased the peptide chain elongation in mouse pancreatic acini in vitro. All secretagogues except VIP inhibited the phosphorylation level of eEF2 on Thr-56 and increased the phosphorylation level of eEF2K on Ser-366, which might correlate with their activation status. MEK inhibitor PD98059 partially reversed the dephosphorylation of eEF2 induced by CCK, as did treatment p38 MAPK inhibitor SB202190, mTOR inhibitor rapamycin, and the phosphatase inhibitor calyculin A.Conclusion CCK increases peptide chain elongation via inducement of dephosphorylation of eEF2 and eEF2 kinase phosphorylation in pancreatic acini in vitro. CCK-induced dephosphorylation of eEF2 in pancreatic acinar cells involves MEK, SAPK/p38, and mTOR, the three intracellular pathways.
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Objective To investigate the methylation status of 14-3-3σ promoter in nasopharyngeal carcinoma cell lines and the influence of de-methylation treatment on 14-3-3σ expression. Methods Methylation status of 14-3-3σ gene promoter and 14-3-3σ mRNA expression were detected by methylation specific PCR (MSP) and RT-PCR in nasopharyngeal carcinoma cell lines CNE1, CNE2,5-8F,6-10B and immortalized nonneoplastic human nasopharyngeal epithelial cell line, NP69. Four nasopharyngeal carcinoma cell lines were treated with 5-asa-2' -deoxycytidine(5-aza-2dC) in different concentration for 72 h, then 14-3-3σ promoter meth-ylation status and m RNA expression were assessed, and western-blot was performed to detect the expression of 14-3-3σ protein. Results 14-3-3σ promoter methylation was detected by MSP in all of the four nasopharyn-geal carcinoma cell lines untreated by 5-aza-2dC whereas not in the treated ones or the immortalized human na-sopharyngeal epithelial cell line, NP69. Accordingly, 14-3-3σ mRNA expression was significantly discounted in untreated nasopharyngeal carcinoma cell lines as compared with NP69. 5-aza-2dC treatment dose-depend-ently reversed 14-3-3σ promoter methylation status and consequently upregulated the expression of 14-3-3σmRNA and protein in 4 nasopharyngeal carcinoma cell lines. High-differentiated CNE1 was more sensitive to 5-aza-2dC than lowly-differentiated CNE2, 5-8F and 6-10B. Conclusion Promoter methylation directly leads to decreased 14-3-3σ gene expression in nasopharyngeal carcinoma cell lines, and 14-3-3σ promoter de-methylation perhaps indicates a new target for nasopharyngeal carcinoma treatment.
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Objective To identify lung adenocarcinoma-associated antigens by using Serologic Proteome Analysis(SERPA),an approach which combined conventional proteome analysis with serological screening.Methods SERPA of four human lung adenocarcinoma tissues were performed.The Western blot imaging films which reacted with autologous patient serum and with control normal serum were obtained and the differential reacting protein spots were recognized.Results Well-resolved,reproducible 2-DE Western blot imaging films of human lung adenocarcinoma reacted with autologous patient sera and the control sera were obtained.Totally(27?5) differentially expressed proteins which only were reactive with lung adenocarcinoma patient sera were found.Some differentially expressed proteins were identified by peptide mass fingerprint(PMF).Some of the proteins were the products of oncogenes,and others were involved in the regulation of cell cycle and signal transduction.Conclusion These results will provide scientific foundation on screening the molecular biomarker for the diagnosis,treatment,and prognosis of the lung adenocarcinoma.