Biomedical subjects

Hui Qin

Publications and source records attributed to Hui Qin.

8 recordsLinked to original sources

PubMed2007

SHP-2 regulates cell growth by controlling the mTOR/S6 kinase 1 pathway.

Cell growth (accumulation in cell mass) ensues through the promotion of macromolecular biosynthesis. S 6 ribosomal kinase 1 (S6K1), which is activated by the mammalian target of rapamycin, is critical for cell growth. The early events that control S6K1 signaling remain unclear. Here we show that SHP-2 suppresses S6K1 activity under conditions of growth factor deprivation. We show that under conditions of growth factor deprivation, S6K1 activity was increased in fibroblasts lacking functional SHP-2 and in cells where knock down of SHP-2 expression was established by small interference RNA. Consistent with these findings, fibroblasts lacking functional SHP-2 exhibited increased cell size as compared with wild type cells. Growth factor deprivation reduces cellular energy, and the energy-sensing 5'-AMP-activated protein kinase (AMPK) negatively regulates S6K1. We found that SHP-2 promoted AMPK activity under conditions of growth factor deprivation (low energy), suggesting that SHP-2 negatively regulates S6K1 via an AMPK-dependent pathway. These results implicate SHP-2 as an early mediator in the S6K1 signaling pathway to limit cell growth in low energy states.

Adenylate Kinase↗

PubMed2006

[Proteomic analysis of proteins related to retinoid acid resistance].

OBJECTIVE: To evaluate the applicability of proteomic methods for shedding light on the mechanisms of All-trans retinoic acid resistance. METHODS: The expression of cellular proteins in the retinoid acid sensitive cell line NB4 and retinoid acid resistant cell line MR2 was analyzed using the two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Differentially expressed proteins were analyzed by mass spectrometry for peptide mass finger and identified by SWISS-PROT protein database. RESULTS: Approximately 600 spots appeared in an sodium dod(SDS-GEL). The match of the expression of cellular proteins between NB4 and MR2 was better. Three significantly differentially expressed proteins were screened and identified to DJ-1 and HSP70, as well as KIAA1289 of which the function is not yet known. CONCLUSION: The utilization of 2D-PAGE, coupled with mass spectrometry is effective in screening the drug resistance-associated proteins and could provide molecular targets for the elucidation of resistance mechanisms.

Antineoplastic Agents↗

PubMed2006

[Comparison between protein detection methods for two-dimensional gel electrophoresis].

The aim of this study was to compare and analyze protein staining in order to select the optimal staining method for proteomic research. Proteins from acute promyelocytic leukemia cell line NB4 and protein molecular weight marker were separated respectively by 2-D or 1-D electrophoresis and detected respectively by the typical Coomassie brilliant blue, the colloidal Coomassie brilliant blue, the modified Coomassie brilliant blue and the silver staining protocols. The protein detection sensitivity, compatibility with mass spectrometry (MS) and facility of the four staining protocols were compared. The results indicated that the silver staining exhibited the highest sensitivity and MS showed the lowest compatibility 10% of protein identification rate. The detection sensitivity of the modified Coomassie brilliant blue staining was superior to that of other two Coomassie brilliant blue stainings, close to but lower than the silver staining, however the compatibility with MS was better (protein identification rate about 55%). It is concluded that the protein detection sensitivity of the modified Coomassie brilliant blue staining is high, and its compatibility with MS is better, this modified Coomassie brilliant blue staining is an optimal staining method for proteomic research.

Coloring Agents↗

PubMed2006

[Analysis of differential protein expression profile between retinoic acid resistant and sensitive acute promyelocytic leukemia cells].

BACKGROUND & OBJECTIVE: This study was to compare the protein expression profiles between retinoic acid (RA) resistant and sensitive acute promyelocytic leukemia (APL) cells by proteomic research method. METHODS: Total cellular proteins extracted from a RA sensitive cell line NB4 and a RA resistant cell line MR2 were separated by two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE). High quality 2D-PAGE protein profiles were obtained and analyzed by PDQuest v7.1 analysis software to screen differentially expressed protein spots. Those sports were identified by mass spectrometry. RESULTS: 2-DE patterns of APL cell lines with high-resolution and reproducibility were obtained. The average spots for MR2 and NB4 cells were 890+/-45 and 912+/-56, respectively. 57 significantly differentially expressed protein spots were screened, among which 23 protein spots were identified to be up-regulated and 34 down-regulated in MR2 cells compared with NB4 cells. Ten proteins were identified by mass spectrometry, with a successful identification rate of 70%. The identified proteins could be classified into different categories: oncogenes,cell cycle regulator and signal transducer. CONCLUSION: The utilization of 2D-PAGE is effective in identifying the protein expression profiles between RA resistant and sensitive APL cells, therefore this study may provide a novel clue to elucidate the drug resistant mechanisms of all-trans retinoic acid.

Antineoplastic Agents↗

PubMed2005

[Screening tumor antigens of ovarian carcinoma by Western blot, immunoprecipitation, and mass spectrometry].

BACKGROUND & OBJECTIVE: Screening tumor antigens plays a key role in early diagnosis of ovarian carcinoma. Several technologies, such as phage antibody library, ribosome display, and serological analysis of recombinant cDNA expression libraries (SEREX), have been applied widely. This study was to screen and identify tumor antigens of ovarian carcinoma by Western blot, immunoprecipitation, and mass spectrometry, and to establish a new methodological entity. METHODS: Western blot was used to find out the obviously different serum in ovarian carcinoma patients; SKOV3 cells lysate was added in the serum; immunoprecipitation was used to enrich antigens; then, the different protein band was gained when compared with normal serum immunoprecipitates, identified by mass spectrometry, and analyzed with bioinformatics. RESULTS: The serum of patient No. 7 was the obviously different one screened with Western blot. Immunoprecipitation and SDS-PAGE showed a different protein band in the serum appeared in the position of about 66.2 ku when compared with normal serum immunoprecipitates. Through mass spectrometry and bioinformatics analysis, heat shock protein 70 (HSP70) and cytokeratin 9 were identified in the different protein band. CONCLUSION: Western blot, immunoprecipitation, and mass spectrometry is an effectively methodological entity for screening and identifying tumor antigens.

Antigens, Neoplasm↗

PubMed2004

WNK kinases: molecular regulators of integrated epithelial ion transport.

PURPOSE OF REVIEW: The WNK kinases are a recently discovered family of serine-threonine kinases that have been shown to play an essential role in the regulation of electrolyte homeostasis. This review focuses on the recent evidence elucidating the functions of these kinases in normal and disease physiology. RECENT FINDINGS: Mutations in WNK1 and WNK4 have been shown to cause pseudohypoaldosteronism type II, a disease featuring hypertension with hyperkalemia. Recent work has demonstrated that WNK4 is a potent inhibitor of diverse epithelial transporters including the thiazide-sensitive sodium chloride co-transporter (NCCT) and the renal outer medullary potassium ion channel. In addition, WNK4 activity promotes paracellular chloride ion flux. Importantly, mutations in WNK4 that cause disease have divergent effects on these transport pathways. WNK4 mutations relieve the inhibition of NCCT, increase the inhibition of the renal outer medullary potassium ion channel, and further increase paracellular chloride ion flux. These findings can explain the observed physiological abnormalities in patients with pseudohypoaldosteronism type II, and support a model in which WNK4 is a molecular switch that can alter the balance between chloride ion reabsorption and potassium ion secretion. The WNK kinases are also found in diverse epithelia throughout the body that are involved in chloride ion flux, suggesting that these kinases may play a general role in the regulation of chloride ion flux. SUMMARY: The WNK kinases define a previously unrecognized signaling pathway that is essential for the integrated regulation of electrolyte homeostasis. Their function has implications for understanding the coordinated regulation of electrolyte homeostasis and blood pressure, and identifies WNKs as dynamic regulators of the paracellular flux pathway.

Epithelium↗

PubMed2003

Phosphorylation screening identifies translational initiation factor 4GII as an intracellular target of Ca(2+)/calmodulin-dependent protein kinase I.

CaMKI is a Ca2+/calmodulin-dependent protein kinase that is widely expressed in eukaryotic cells and tissues but for which few, if any, physiological substrates are known. We screened a human lung cDNA expression library for potential CaMKI substrates by solid phase in situ phosphorylation ("phosphorylation screening"). Multiple overlapping partial length cDNAs encoding three proteins were detected. Two of these proteins are known: 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase and eukaryotic translation initiation factor (eIF) 4GII. To determine whether CaMKI substrates identified by phosphorylation screening represent authentic physiological targets, we examined the potential for [Ca2+]i- and CaMKI-dependent phosphorylation of eIF4GII in vitro and in vivo. Endogenous eIF4GII immunoprecipitated from HEK293T cells was phosphorylated by CaMKI, in vitro as was a recombinant fragment of eIF4GII encompassing the central and C-terminal regions. The latter phosphorylation occurred with favorable kinetics (Km = 1 microm; kcat = 1.8 s-1) at a single site, Ser1156, located in a segment of eIF4GII aligning with the phosphoregion of eIF4GI. Phosphopeptide mapping and back phosphorylation experiments revealed [Ca2+]i-dependent, CaMKI site-specific, eIF4GII phosphorylation in vivo. This phosphorylation was blocked by kinase-negative CaMKI consistent with a requirement for endogenous CaMKI for in vivo eIF4GII phosphorylation. We conclude that phosphorylation screening is an effective method for searching for intracellular targets of CaMKI and may have identified a new role of Ca2+ signaling to the translation apparatus.

Amino Acid Sequence↗

PubMed2002

[The effect of interferon alone, cytosine arabinoside alone and their combined effect on hematopoietic progenitors of chronic myeloid leukemia in vitro].

OBJECTIVE: In order to search for more effective treatment regimen of chronic myeloid leukemia (CML). METHODS: Semisolid culture and conventional chromosome assay were used to evaluate the effect of interferon (IFN) and Ara-c on K562 cell line and BMMNCs from CML patients and normal controls. RESULTS: IFN had no obvious inhibitory effect on K562 cell. IFN and Ara-c had preferential inhibitory effect on CFU-GM growth of CML and selective cytotoxic effect on CML Ph+ cell. The combination of IFN with Ara-c enhanced the cytotoxic effect of IFN or Ara-c alone on CML cells. CONCLUSION: IFN and Ara-c can be selected for therapy of CML in chronic phase. The combination of IFN with Ara-c may be more effective than IFN or Ara-c alone for the therapy of CML.

Adult↗