1. |
- Anderson, Per, et al.
(author)
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Differential activation of signal transducer and activator of transcription (STAT)3 and STAT5 and induction of suppressors of cytokine signalling in T(h)1 and T(h)2 cells
- 2003
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In: International Immunology. - : Oxford University Press (OUP). - 1460-2377. ; 15:11, s. 1309-1317
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Journal article (peer-reviewed)abstract
- Cytokines direct the differentiation of naive CD4(+) T cells into either IFN-gamma-producing T(h)1 cells or IL-4-producing T(h)2 cells. In this study, we analyzed the activation of signal transducer and activator of transcription (STAT)1, STAT3 and STAT5 (together with STAT4 and STAT6), and the expression of the recently identified suppressor of cytokine signalling (SOCS) proteins, in differentiated T(h)1 and T(h)2 cells, both before and after re-stimulation with anti-CD3 and anti-CD28. In addition to the polarized activation of STAT4 in T(h)1 cells and STAT6 in T(h)2 cells, we found that STAT3 and STAT5 are selectively activated in T(h)1 cells after differentiation. This activation of STAT3 and STAT5 was maintained after TCR re-stimulation. The selective activation of STAT3 and STAT5 in T(h)1 cells was associated with differential induction of SOCS molecules. After restimulation, SOCS1 expression was significantly increased in T(h)2 cells, but not in T(h)1 and nonpolarized 'T-h' cells. Additionally, the level of CIS was higher in T(h)2 cells compared with T(h)1 and T-h cells. In contrast, the expression of SOCS3 was higher in T(h)1 cells. The differential induction of SOCS proteins was paralleled by the differential expression of cytokines in re-stimulated T(h)1 and T(h)2 cells (IFN-gamma and IL-4/IL-13 respectively). Our results suggests that STAT3 and STAT5, possibly regulated by the SOCS proteins, may play a role in the differentiation of T-h cells, and in the maintenance of the T(h)1 and T(h)2 phenotype.
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2. |
- Chen, S, et al.
(author)
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Functional association of cytokine-induced SH2 protein and protein kinase C in activated T cells
- 2003
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In: International Immunology. - : Oxford University Press (OUP). - 1460-2377. ; 15:3, s. 403-409
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Journal article (peer-reviewed)abstract
- TCR signaling is mediated by intracellular signaling molecules and nuclear transcription factors, which are tightly regulated by interaction with regulatory proteins such as Grb2 and SLAP. We reported recently that TCR stimulation induces the expression of cytokine-induced SH2 protein (CIS). The expression of CIS promotes TCR-mediated activation. We have now found specific interactions between CIS and activated protein kinase C (PKC) alpha, beta and theta in TCR-stimulated T cells. CIS was shown by in vitro kinase assay to associate with activated PKC. In CIS-expressing T cells isolated from CIS-transgenic mice, the amount of activated PKC associated with CIS was found to increase following TCR stimulation. By immunohistochemical analysis, CIS was also found to co-localize with PKCtheta at the plasma membrane of activated T cells. In addition to the interaction and intracellular co-localization of the CIS and PKC, an increase in the activation of AP-1 and NF-kappaB was noted in CIS-expressing T cells, after stimulation by either anti-CD3/CD28 or phorbol myristate acetate + ionomycin. These results suggest that CIS regulates PKC activation, and that this may be important for the activation of both the AP-1 and NF-kappaB pathways in TCR signaling.
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3. |
- Ding, HT, et al.
(author)
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Parallel cloning, expression, purification and crystallization of human proteins for structural genomics
- 2002
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In: Acta Crystallographica. Section D: Biological Crystallography. - 1399-0047. ; 58, s. 2102-2108
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Journal article (peer-reviewed)abstract
- 54 human genes were selected as test targets for parallel cloning, expression, purification and crystallization. Proteins from these genes were selected to have a molecular weight of between 14 and 50 kDa, not to have a high percentage of hydrophobic residues (i.e. more likely to be soluble) and to have no known crystal structures and were not known to be subunits of heterocomplexes. Four proteins containing transmembrane regions were selected for comparative tests. To date, 44 expression clones have been constructed with the Gateway(TM) cloning system (Invitrogen, The Netherlands). Of these, 35 clones were expressed as recombinant proteins in Escherichia coli strain BL21 (DE3)-pLysS, of which 12 were soluble and four have been purified to homogeneity. Crystallization conditions were screened for the purified proteins in 96-well plates under oil. After further refinement with the same device or by the hanging-drop method, crystals were grown, with needle, plate and prism shapes. A 2.12 Angstrom data set was collected for protein NCC27. The results provide insights into the high-throughput target selection, cloning, expression and crystallization of human genomic proteins.
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4. |
- Li, Li, et al.
(author)
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Insulin induces SOCS-6 expression and its binding to the p85 monomer of phosphoinositide 3-kinase, resulting in improvement in glucose metabolism
- 2004
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In: Journal of Biological Chemistry. - 1083-351X. ; 279:33, s. 34107-34114
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Journal article (peer-reviewed)abstract
- The suppressors of cytokine signaling ( SOCS) family is thought to act largely as a negative regulator of signaling by cytokines and some growth factors. Surprisingly, the SOCS-6 transgenics had no significant defects in the cytokine signaling and hematopoietic system but displayed significant improvements in glucose metabolism. Insulin stimulation of Akt/protein kinase B was also potentiated. Biochemical analysis showed that, after insulin stimulation, SOCS-6 interacted with the monomeric p85 subunit of class-Ia phosphoinositide ( PI) 3-kinase but not with p85/p110 dimers. Furthermore, SOCS-6 expression is transiently increased by serum and insulin in normal fibroblasts. However, both the mRNA and protein of SOCS-6 were rapidly degraded after induction by insulin. The degradation of the SOCS-6 protein was partially inhibited by a proteasome inhibitor, suggesting a proteasome-mediated degradation mechanism. In contrast, SOCS-6- associated p85 was not degraded and could be recruited to the newly synthesized SOCS-6 molecules in the presence of insulin, suggesting that SOCS-6 expression and its interaction with p85, but not the degradation, is regulated by insulin. The phenotype of SOCS-6 transgenic mice bears a striking resemblance to p85 knock-out mouse models in which glucose metabolism stimulated by insulin is significantly improved despite reduced activation of PI 3-kinase. This suggests that monomeric p85 might play a physiologically important role in attenuating signaling through PI 3-kinase-dependent pathways in unstimulated cells. Therefore, our results indicate that SOCS-6 may provide a dynamically regulated mechanism by which insulin can transiently overcome the negative effects that p85 monomers have on signaling via PI 3-kinase-dependent signaling pathways.
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5. |
- Chen, W, et al.
(author)
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Full-color emission from In2S3 and ln(2)S(3): Eu3+ nanoparticles
- 2004
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 108:32, s. 11927-11934
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Journal article (peer-reviewed)abstract
- New observations on the luminescence Of In2S3 and europium-doped In2S3 nanoparticles show a green (5 10 nm) emission from In2S3 and In1.8Eu0.2S3 nanoparticles while a blue (425 nm) emission is observed from ln(1.6)Eu(0.4)S(3) nanoparticles. Both the blue and green emissions have large Stokes shifts of 62 and 110 nm, respectively. Excitation with longer-wavelength photons causes the blue emission to shift to a longer wavelength while the green emission wavelength remains unchanged. The lifetimes of both the green and blue emissions are similar to reported values for excitonic recombination. When doped with Eu3+, in addition to the broad blue and green emissions, a red emission near 615 nm attributed to Eu3+ is observed. Temperature dependences on nanoparticle thin films indicate that with increasing temperature, the green emission wavelength remains constant, however, the blue emission shifts toward longer wavelengths. Based on these observations, the blue emission is attributed to exciton recombination and the green emission to Indium interstitial defects. These nanoparticles show full-color emission with high efficiency, fast lifetime decays, and good stability; they are also relatively simple to prepare, thus making them a new type of phosphor with potential applications in lighting, flat-panel displays, and communications.
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6. |
- Chen, W, et al.
(author)
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Temperature and pressure dependences of the Mn2+ and donor-acceptor emissions in ZnS : Mn2+ nanoparticles
- 2002
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In: Applied Physics Reviews. - : AIP Publishing. - 1931-9401. ; 92:4, s. 1950-1955
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Journal article (peer-reviewed)abstract
- Temperature and pressure dependent measurements have been performed on 3.5 nm ZnS:Mn2+ nanoparticles. As temperature increases, the donor-acceptor (DA) emission of ZnS:Mn2+ nanoparticles at 440 nm shifts to longer wavelengths while the Mn2+ emission (T-4(1)-(6)A(1)) shifts to shorter wavelengths. Both the DA and Mn2+ emission intensities decrease with temperature with the intensity decrease of the DA emission being much more pronounced. The intensity decreases are fit well with the theory of thermal quenching. As pressure increases, the Mn2+ emission shifts to longer wavelengths while the DA emission wavelength remains almost constant. The pressure coefficient of the DA emission in ZnS:Mn2+ nanoparticles is approximately -3.2 meV/GPa, which is significantly smaller than that measured for bulk materials. The relatively weak pressure dependence of the DA emission is attributed to the increase of the binding energies and the localization of the defect wave functions in nanoparticles. The pressure coefficient of Mn2+ emission in ZnS:Mn2+ nanoparticles is roughly -34.3 meV/GPa, consistent with crystal field theory. The results indicate that the energy transfer from the ZnS host to Mn2+ ions is mainly from the recombination of carriers localized at Mn2+ ions. (C) 2002 American Institute of Physics.
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7. |
- Guan, Z, et al.
(author)
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Preparation and crystallization of a Bacillus subtilis arsenate reductase
- 2001
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In: Acta Crystallographica. Section D: Biological Crystallography. - 1399-0047. ; D57, s. 1718-1721
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Journal article (peer-reviewed)abstract
- Arsenate reductase (AR) in B. subtilis is encoded by the chromosomal arsC gene. Together with arsB and arsR, arsC participates in detoxification processes for the arsenate and arsenite ions. Full-length arsenate reductase without any modification has been expressed in Escherichia coli and purified in a soluble form. The recombinant protein has been crystallized at 277 K using polyethyleneglycol (PEG) or poly(ethyleneglycol) methyl ether (PME) as the main precipitant. At least two forms of crystals large enough for data collection have been obtained from wild-type protein under different conditions. An orthorhombic crystal diffracted to beyond 2.2 Å with space group P212121 and unit-cell parameters a = 51.22, b = 91.62, c = 101.93 Å. A near-complete data set has been collected to 2.5 Å. The application of the flash-annealing technique was crucial for high resolution during the data collection. The SeMet-substituted AR has also been produced and crystallized under very similar conditions as the wild type, but the unit-cell parameters are very different. The crystals of the SeMet protein diffracted to higher resolution than those of the wild type.
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8. |
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9. |
- Li, M., et al.
(author)
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In vitro protein refolding by chromatographic procedures
- 2004
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In: Protein Expression and Purification. ; 33:1, s. 1-10
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Journal article (peer-reviewed)abstract
- In vitro protein refolding is still a bottleneck in both structural biology and in the development of new biopharmaceuticals, especially for commercially important polypeptides that are overexpressed in Escherichia coli. This review focuses on protein ref
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