Biomedical subjects

Qiong Jiang

Publications and source records attributed to Qiong Jiang.

At least 19 recordsLinked to original sources

PubMed2007

Role of the intracellular domain of IL-7 receptor in T cell development.

Signals from the IL-7R are uniquely required for T cell development and maintenance, despite the resemblance of IL-7R to other cytokine receptors and the apparent sharing of common signaling pathways. This unique requirement could either reflect unique expression of IL-7R or IL-7, or it could indicate that the IL-7R delivers unique signals. To determine whether the IL-7R provided unique signals, we exchanged its intracellular domain with that of other cytokine receptors: IL-4R, IL-9R, and prolactin receptor (PRLR). Chimeric receptors were used to reconstitute development of IL-7R(-/-) hemopoietic progenitors by transducing the receptors in retroviral vectors. Whereas IL-7R(-/-) thymocytes are arrested at the double-negative stage, IL-4R, IL-9R, or PRLR all imparted some progression to the double-positive stage. IL-4R and PRLR gave only small numbers of thymocytes, whereas IL-9R gave robust alphabeta T cell development and reconstitution of peripheral CD4 and CD8 cells, indicating that it can duplicate many of the functions of IL-7R. However, IL-9R failed to reconstitute rearrangement of the TCRgamma locus or development of gammadelta T cells. Thus, the IL-7R signals required in the alphabeta T cell lineage (such as survival and proliferation) are not unique to this receptor, whereas rearrangement of the TCRgamma locus may require a signal that is not shared by other receptors.

Animals↗

PubMed2006

IL-7 promotes T cell proliferation through destabilization of p27Kip1.

Interleukin (IL)-7 is required for survival and homeostatic proliferation of T lymphocytes. The survival effect of IL-7 is primarily through regulation of Bcl-2 family members; however, the proliferative mechanism is unclear. It has not been determined whether the IL-7 receptor actually delivers a proliferative signal or whether, by promoting survival, proliferation results from signals other than the IL-7 receptor. We show that in an IL-7-dependent T cell line, cells protected from apoptosis nevertheless underwent cell cycle arrest after IL-7 withdrawal. This arrest was accompanied by up-regulation of the cyclin-dependent kinase inhibitor p27Kip1 through a posttranslational mechanism. Overexpression of p27Kip1 induced G1 arrest in the presence of IL-7, whereas knockdown of p27Kip1 by small interfering RNA promoted S phase entry after IL-7 withdrawal. CD4 or CD8 T cells transferred into IL-7-deficient hosts underwent G1 arrest, whereas 27Kip1-deficient T cells underwent proliferation. We observed that IL-7 withdrawal activated protein kinase C (PKC)theta and that inhibition of PKCtheta with a pharmacological inhibitor completely blocked the rise of p27Kip1 and rescued cells from G1 arrest. The conventional pathway to breakdown of p27Kip1 is mediated by S phase kinase-associated protein 2; however, our evidence suggests that PKCtheta acts via a distinct, unknown pathway inducing G1 arrest after IL-7 withdrawal from T cells. Hence, IL-7 maintains T cell proliferation through a novel pathway of p27Kip1 regulation.

Animals↗

PubMed2006

Stat5a/b are essential for normal lymphoid development and differentiation.

Cytokines that use the common gamma chain gammac are critical for lymphoid development and function. Mutations of the IL-7 receptor, gammac, or its associated kinase, Jak3, are the major cause of human severe combined immunodeficiency. Although activated by IL-7, Stat5a/b (Stat, signal transducer and activator of transcription) have been thought to play limited roles in lymphoid development. However, we now show that mice completely deficient in Stat5a/b have severely impaired lymphoid development and differentiation. Absence of Stat5 also abrogates T cell receptor gamma rearrangement and survival of peripheral CD8(+) T cells. Thus, deficiency of Stat5 results in severe combined immunodeficiency, similar in many respects to deficiency of IL-7R, gammac, and Jak3.

Animals↗

PubMed2006

Lsh is involved in de novo methylation of DNA.

Deletion of Lsh perturbs DNA methylation patterns in mice yet it is unknown whether Lsh plays a direct role in the methylation process. Two types of methylation pathways have been distinguished: maintenance methylation by Dnmt1 occurring at the replication fork, and de novo methylation established by the methyltransferases Dnmt3a and Dnmt3b. Using an episomal vector in Lsh-/- embryonic fibroblasts, we demonstrate that the acquisition of DNA methylation depends on the presence of Lsh. In contrast, maintenance of previously methylated episomes does not require Lsh, implying a functional role for Lsh in the establishment of novel methylation patterns. Lsh affects Dnmt3a as well as Dnmt3b directed methylation suggesting that Lsh can cooperate with both enzymatic activities. Furthermore, we demonstrate that embryonic stem cells with reduced Lsh protein levels show a decreased ability to silence retroviral vector or to methylate endogenous genes. Finally, we demonstrate that Lsh associates with Dnmt3a or Dnmt3b but not with Dnmt1 in embryonic cells. These results suggest that the epigenetic regulator, Lsh, is directly involved in the control of de novo methylation of DNA.

Animals↗

PubMed2005

[Effect of aloe vera polysaccharide on the release of cytokines and nitric oxide in cultured human keratinocytes].

OBJECTIVE: To investigate the effects of polysaccharide extracted from Aloe Barbadensis on the release of cytokines and nitric oxide (NO) in cultured human keratinocytes. METHODS: The levels of transforming growth factor-alpha (TGF-alpha), TGF-beta1, interleukin-1beta (IL-1beta), IL-6, IL-8, tumor necrosis factor (TNF) and NO in the supernatants of keratinocyte culture in which culture media containing 25, 50, 100, 200, 400 microg/ml, respectively of aloe polysaccharide were assayed. In the control group equal volume of media without the polysaccharide was used. RESULTS: Compared with control group, the levels of TGF-alpha, TGF-beta1, IL-1beta, IL-6, IL-8 and TNF in the supernatants of cultured keratinocytes were significantly higher when aloe polysaccharide was added (P<0.05 or P<0.01), and they were positively correlated to the concentration of aloe polysaccharide (P<0.01). However, aloe polysaccharide markedly decreased the level of NO in a dose dependent manner (P<0.01). CONCLUSION: Aloe polysaccharide could promote keratinocytes to secrete TGF-alpha, TGF-beta1, IL-1beta, IL-6, IL-8 and TNF, and inhibit the release of NO.

Aloe↗

PubMed2005

[Effect of shexiang baoxin pill in alleviating myocardial fibrosis in spontaneous hypertensive rats].

OBJECTIVE: To investigate the effects and mechanisms of Shexiang Baoxin Pill (SBP) on myocardial fibrosis in spontaneous hypertensive rats (SHR). METHODS: SHR of 12 weeks old were divided into the SBP group, the control group (treated with benazepril) and the model control group. The effects on such indexes as systolic blood pressure (SBP), left ventricular mass (LVM), left ventricular mass index (LVMI), content of myocardial collagen (MC) in left ventricle, extracellular matrix fibronectin (FN), laminin (LN), cardiac fibroblast (cFb) and transforming growth factor-beta1 (TGF-beta1) were determined after 12 weeks of treatment. RESULTS: SBP had no marked pressure depressive effect, but had the effect similar to that of benazepril in reducing the level of LVM, LVMI and content of MC (P < 0.05), as well as the content of LN, FN in myocardium, cFb count and TGF-beta1 expression (P < 0.05). CONCLUSION: SBP can prevent and treat myocardial fibrosis, whose action is independent of its hypotensive effect. The mechanism may be associated with such factors as the decrease of MC synthesis in left ventricle and the deposition of extracellular matrix.

Animals↗

PubMed2005

[Influence of polysaccharide from Aloe vera on the proliferation of the human epithelial cells cultured in vitro].

OBJECTIVE: To investigate the influence of polysaccharide from Aloe Vera (AP) on the proliferation of the human epithelial cells cultured in vitro. METHODS: The human epithelial cells undergoing 3 to 4 passages of confluence culture were randomly divided into control and 25, 50, 100, 200 and 400 mg/L AP groups according to different dosage of the polysaccharide (AP) added into the culture medium. In the control group (C), equal volume of DK-SFM medium was added to the culturing cells. The conjugation time of epithelial cells, the changes in the cell morphology and ultrastructure were observed under inverted phase contrast microscope and transmission electron microscope, respectively. The cell proliferation was measured by MTT, cell count analysis and [(3)H]-TdR incorporation. Flow cytometry analysis was employed to detect the cell cycle. The leakage rate of lactate dehydrogenase (LDH) was assayed for the evaluation of the epithelial cell injury. RESULTS: There was no significant difference in the morphology of the epithelial cells among the groups under inverted phase contrast microscope. But under the transmission electron microscope (TEM), the cells in 100 to 400 mg/L AP groups were seen to have proliferated actively, with euchromatin dominant in the nuclei, while heterochromatin was dominant in the cellular nucleus in control and 25 mg/L AP groups. The confluence time of epithelial cells in 50, 100, 200, 400 mg/L AP groups (154 +/- 12, 141 +/- 20, 130 +/- 19, 124 +/- 13) h preceded noticeably than that in control group (182 +/- 8) h, (P < 0.01). The cell proliferation in 100, 200, 400 mg/L groups reached the peak on the 5th day after AP treatment, while that in control and other groups was delayed by 1 to 2 days. The survival rate of the cells in 25 to 400 mg/L AP groups increased dramatically compared with that in control group, with its [(3)H]-TdR incorporation levels significantly increased in a dose dependent manner. The leakage rate of LDH in 200 and 400 mg/L AP groups was lower than that in control group (P < 0.01). The flow cytometric analysis of the cell cycle distribution revealed that the percentage of cell cycle from phase G0/G1 to G2/M and S in 25 to 400 mg/L AP groups increased significantly in a dose dependent manner compared with that in control group (P < 0.01). CONCLUSION: AP might be beneficial to the protection of epithelial cells by promoting cell proliferation through inducing the progression of epidermal cells from phase G0/G1 into G2/M and S phases.

Aloe↗

PubMed2005

[Effect of Aloe coarse polysaccharide on cytokine secretion of keratinocytes in vitro].

OBJECTIVE: To study the effects of Aloe coarse polysaccharide on the levels of growth factors (EGF, TGF-alpha, TGF-beta1) and interleukins (IL-1beta, IL-6, IL-8) and tumor necrosis factor (TNF) in cultured keratinocytes. METHOD: The cultured keratinocytes were treated with Aloe coarse polysaccharide at concentrations of 75, 150, 300, 600, 1 200 mg x L(-1) land the equal volume of media as control group. The levels of EGF, TGF-alpha, TGF-beta1, IL-1beta, IL-6, IL-8 and TNF in the supernatants of cultured keratinocytes were assayed by enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA). RESULT: Compared with the control group, the levels of EGF, TGF-alpha, IL-1beta, IL-6 and IL-8 were significantly increased by treatment with Aloe coarse polysaccharide (P < 0.05, P < 0.01) and in a dose dependent manner, and the levels of TGF-beta1 and TNF were also increased but no statistical significance. CONCLUSION: Aloe coarse polysaccharide may promote keratinocytes to secrete EGF, TGF-alpha, IL-1beta, IL-6 and IL-8.

Aloe↗

PubMed2004

Interleukin-7 inactivates the pro-apoptotic protein Bad promoting T cell survival.

Interleukin-7 (IL-7) is a cytokine that is required for T cell development and survival. The anti-apoptotic function of IL-7 is partly through induction of Bcl-2 synthesis and cytosolic retention of Bax. Here we show that the Bcl-2 homology 3 domain-only protein, Bad, is involved in cell death following IL-7 withdrawal from D1 cells, an IL-7-dependent murine thymocyte cell line. IL-7 stimulation resulted in the inactivation of Bad by phosphorylation at Ser-112, -136, and -155. The phosphoinositide 3-kinase (PI3K)/Akt pathway has been implicated previously in Bad phosphorylation. In response to IL-7, the PI3K/Akt pathway induced phosphorylation at Ser-136 and -155, but Ser-112 was partly independent of the PI3K/Akt pathway, indicating an as yet unknown pathway in this response. Following IL-7 withdrawal, dephosphorylated Bad translocated from cytosol to mitochondria, bound to Bcl-2, and accelerated cell death. Thus, the inactivation of Bad contributes to the survival function of IL-7.

Animals↗

PubMed2004

Genomic organization and transcriptional analysis of gonadotropin-regulated testicular RNA helicase--GRTH/DDX25 gene.

The gonadotropin-regulated testicular RNA helicase (GRTH/DDX25) is a new member of the DEAD-box protein family. Phylogenetic analysis revealed that GRTH is distantly related to other members of the family. GRTH is transcriptionally up-regulated by gonadotropin, displays ATPase and RNA helicase activities, and participates in germ cell development. To understand the regulation of GRTH gene expression, we investigated its structural organization and aspects of basal transcriptional regulation at the promoter domain. The 20-kb mouse GRTH gene contains 12 coding exons and all but one of its conserved helicase motifs are contained within single exons. GRTH is a TATA-less gene with multiple transcriptional start sites (TSS), GC-rich sequences and a promoter located within -205/+63 bp of the gene. Sequences -852/-354 and -501/-354 bp caused 40-60% and >80% inhibition of transcription in expressing and non-expressing cells, respectively. Transcriptional activity was recovered only in expressing cells by the addition of upstream sequences (-1085/-852 bp). Sp1/Sp3 supported basal transcriptional activity in all cell types, while E-box was an activator-binding site only in non-expressing cells. These findings indicate that a differential pattern of transcriptional regulation may be involved in the control of GRTH gene expression in a cell-specific manner.

5' Flanking Region↗

PubMed2004

IL-7 induces tyrosine phosphorylation of clathrin heavy chain.

IL-7 induction of protein tyrosine phosphorylation was examined in an IL-7-dependent thymocyte cell line, D1, which was generated from a p53-/- mouse. Anti-phosphotyrosine antibody was used both to immunoprecipitate and Western blot, and showed that IL-7 induced tyrosine phosphorylation of a protein with a molecular weight of approximately 200 kDa. The P200 band was purified by reversed-phase high-performance liquid chromatography. Amino acid sequencing by mass spectrometry revealed three peptides identical to rat clathrin heavy chain (CHC) 1 (192 kDa), and this was confirmed by blotting with an anti-clathrin antibody. Stimulation of normal pro-T cells by IL-7 showed an increased tyrosine phosphorylation of clathrin heavy chain. Tyrosine phosphorylation of clathrin heavy chain was strongly induced by IL-7 and to a lesser extent by IL-4, while no effect could be observed with the cytokines IL-2, IL-9 and IL-15, whose receptors share the gammac chain. Phosphorylation of clathrin heavy chain was found to be sensitive to Jak3 inhibitors but not to Src inhibitors. Clathrin is involved in internalization of many receptors, and its phosphorylation by IL-7 stimulation may affect the internalization of the IL-7 receptor.

Animals↗

PubMed2004

Distinct regions of the interleukin-7 receptor regulate different Bcl2 family members.

The antiapoptotic function of the interleukin-7 (IL-7) receptor is related to regulation of three members of the Bcl2 family: synthesis of Bcl2, phosphorylation of Bad, and cytosolic retention of Bax. Here we show that, in an IL-7-dependent murine T-cell line, different regions of the IL-7 receptor initiate the signal transduction pathways that regulate these proteins. Both Box1 and Y449 are required to signal Bcl2 synthesis and Bax cytosolic retention. This suggests a sequential model in which Jak1, which binds to Box1, is first activated and then phosphorylates Y449, leading to Bcl2 and Bax regulation, accounting for approximately 90% of the survival function. Phosphorylation of Bad required Box1 but not Y449, suggesting that Jak1 also initiates an additional signaling cascade that accounts for approximately 10% of the survival function. Stat5 was activated from the Y449 site but only partially accounted for the survival signal. Proliferation required both Y449 and Box1. Thymocyte development in vivo showed that deletion of Y449 eliminated 90% of alphabeta T-cell development and completely eliminated gammadelta T-cell development, whereas deleting Box 1 completely eliminated both alphabeta and gammadelta T-cell development. Thus the IL-7 receptor controls at least two distinct pathways, in addition to Stat5, that are required for cell survival.

Animals↗

PubMed2004

[The change of the erythrocyte chemokine receptor binding activity in the shock stage of burn rats].

AIM: To investigate the change of the erythrocyte chemokine receptor(ECKR) binding activity in the shock stage of burn rats. METHODS: SD rats were randomly divided into two group, burn and control groups. In the burn group rats, 30% total body surface area (TBSA)were scalded to III degree. The binding activity of rat ECKR in the shock stage was detected by ELISA using IL-8 as ligand at various time points (0.5, 2, 4, 8, 16, 24 and 48 hours) after burn. RESULTS: Compared with control group, the binding activity of rat ECKR declined significantly half an hour after burn and maintained at low level for 48 hours (P<0.01). The comparison of the binding activity of rat ECKR at various time points after burn indicated that the binding activity declined gradually from 2 hours (P<0.01-0.05), reached lowest value 24 hrs, and then rose significantly 48 hrs after burn (P<0.01). CONCLUSION: The ECKR binding activity declined significantly after burn, suggesting erythrocytes may participate in the regulation of chemokines and play some role in the inflammation.

Animals↗

PubMed2004

[Cloning of a laccase gene from Flammulina velutipes and study on its expression in Pichia pastoris].

Laccase(EC1.10.3.2) can be used for enzymatic detoxification of lignocellulosic hydrolysates. By using molecular techniques such as RACE (rapid amplification of cDNA ends) and Genome-Walking, a laccase gene and its corresponding full-length cDNA were cloned from Flammulina velutipes and designated as glccFv and IccFv. The sequences were submitted to GenBank, and the accession numbers obtained were AY485826 and AY450406, respectively. Analysis of amino acids sequence suggested that one laccase from Polyporus ciliatus possessed the highest homology with the protein encoded by lccFv showing for 72%. The ORF (open reading frame) of lccFv was transformed into Pichia pastoris strain GS115 through the P. pastoris expression vector pHBM906, which contains both the promoter and transcription terminator of the AOX1 gene. The recombinant laccase LCCFv was detected from the engineering strain GS115 (pHBM557) which was fermented with BMMY liquid medium and induced by 1.0% (V/V) methanol at 20 degrees C with the highest expression level (0.1070 U/mL). The optimal reaction temperature of LCCFv that secreted from P. pastoris GS115(pHBM557) was 45 degrees C, the optimal reaction pH value was pH3.9 and the thermostability and pH stability were very well under the optimal conditions.

Base Sequence↗

PubMed2003

[Change of the erythrocyte chemokine receptor binding activity in scalded rats with Pseudomonas aeruginosa infection].

OBJECTIVE: To explore the influence of infection on the erythrocyte chemokine receptor (ECKR) binding activity in severely scalded rats. METHODS: The Sprague-Dawley (SD) rats were randomly divided into three group: sham scald group (A), burn and infection group (B) and infection group (C). The B group rats were scalded with 30% total body surface area (TBSA) of III degree, and the rats ECKR binding activity with interleukin-8 (IL-8) as ligand were detected by enzyme-linked immunosorbent assay (ELISA) at 1, 2, 4, 6 and 8 hours after infection. RESULTS: Compared to that in A group, ECKR binding activities declined significantly (both P<0.01) after infection in both of B and C groups, but they increased at 8 hours (P<0.01). ECKR binding activity in B group was significantly less at 2, 8 hours than that in C group after infection (both P<0.05). The declining range of ECKR binding activity was more in B group, in which the decline of ECKR binding activity appeared earlier (2 hours) than that in C (6 hours) group. CONCLUSION: The infection lead to the decline of ECKR binding activity in burned rats, and the erythrocytes might participate in the chemokine regulation and play a novel role in the infection.

Animals↗

PubMed1999

Cloning of Glial Cell Line-derived Neurotrophic Factor Gene and Its Expression in Eukaryotic Cells.

Glial cell line-derived neurotrophic factor gene (gdnf) was obtained by RT-PCR method. Its pro-duct in COS7 cells showed neurotrophic and protective effect on the dopaminergic neurons. Then gdnf gene was cloned into retrovirus vector pLNCX and packaged with PA317. Infectious particles thus obtained were used to infect rat myoblast cell line L-6TG. A cell clone L-6TG/gdnf was obtained after G418 selection. It will be applied to the ex vivo gene therapy study of Parkinson's disease.

Journal Article↗

PubMed1999

Preliminary Study on Gene Therapy of PD Monkey Using Microcapsulated Rat Transgenetic Myoblasts.

Rat myoblast cells transfected with tyrosine hydroxylase gene were microcapsulated using the ALG/PLL system. These microcapsulated cells could survive grow and produce tyrosine hydroxylase(TH)for at least two months in vitro. After the implantation of these microcapsules into monkey striatum microcapsulated cells still survived one month more. No obvious gliosis was seen around implanted microcapsules. Then the microcapsules were transplanted into the striatum of PD monkeys and their typical PD rotation numbers were significantly decreased.

Journal Article↗

PubMed1999

Expression of Brain-derived Neurotrophic Factor (BDNF) Gene in Rat Myoblast Cells.

Brain-derived neurotrophic factor (BDNF) gene was cloned into retrovirous vector plasmid pLNCX to form the pLNC/BDNF. After packaging in PA317 cell line, the infectious particles were used to infect rat myoblast cell line L-6TG. After selection with G418, the L-6TG/BDNF cells were collected. Results from Southern blot show that bdnf gene has successfully integrated into the L-6TG genomic DNA. The expression of bdnf gene has been proved by Northern blot and Dot blot. The content of BDNF in the culture medium of L-6TG/BDNF was about 25 ng.10(-6) cells per 24 h per ml.

Journal Article↗