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21.
Balasubramaniam D Paul LN Homan KT Hall MC Stauffacher CV 《Protein science : a publication of the Protein Society》2011,20(7):1172-1181
EphA2 receptor tyrosine kinase and the human cytoplasmic protein tyrosine phosphatase (HCPTP) are overexpressed in a number of epithelial cancers. Overexpressed EphA2 in these cancers shows a significant decrease in phosphotyrosine content which results in suppression of receptor signaling and endocytosis and an increase in metastatic potential. The decreased phosphotyrosine content of EphA2 has been associated with decreased contact with its ligand, ephrin A1 and dephosphorylation by HCPTP. Potential specificity of the two HCPTP variants for tyrosines on EphA2 has not been investigated. We have used a mass spectrometry assay to measure relative rates of dephosphorylation for the two HCPTP variants at phosphotyrosine sites associated with control of the EphA2 kinase activity or interaction with downstream targets. Our results suggest that although both variants dephosphorylate the EphA2 receptor, the rate and specificity of dephosphorylation for specific tyrosines are different for HCPTP-A and HCPTP-B. The SAM domain tyrosine Y960 which has been implicated in downstream PI3K signaling is dephosphorylated exclusively by HCPTP-B. The activation loop tyrosine (Y772) which directly controls kinase activity is dephosphorylated about six times faster by HCPTP-A. In contrast, the juxtamembrane tyrosines (Y575, Y588 and Y594) which are implicated in both control of kinase activity and downstream signaling are dephosphorylated by both variants with similar rates. This difference in preference for dephosphorylation sites on EphA2 not only illuminates the different roles of the two variants of the phosphatase in EphA2 signaling, but also explains why both HCPTP variants are highly conserved in most mammals. 相似文献
22.
Vaccine-stimulated, adoptively transferred CD8+ T cells traffic indiscriminately and ubiquitously while mediating specific tumor destruction 总被引:2,自引:0,他引:2
Palmer DC Balasubramaniam S Hanada K Wrzesinski C Yu Z Farid S Theoret MR Hwang LN Klebanoff CA Gattinoni L Goldstein AL Yang JC Restifo NP 《Journal of immunology (Baltimore, Md. : 1950)》2004,173(12):7209-7216
It has been suggested that antitumor T cells specifically traffic to the tumor site, where they effect tumor destruction. To test whether tumor-reactive CD8(+) T cells specifically home to tumor, we assessed the trafficking of gp100-specific pmel-1 cells to large, vascularized tumors that express or do not express the target Ag. Activation of tumor-specific CD8(+) pmel-1 T cells with IL-2 and vaccination with an altered peptide ligand caused regression of gp100-positive tumors (B16), but not gp100-negative tumors (methylcholanthrene 205), implanted on opposing flanks of the same mouse. Surprisingly, we found approximately equal and very large numbers of pmel-1 T cells (>25% of all lymphocytes) infiltrating both Ag-positive and Ag-negative tumors. We also found evidence of massive infiltration and proliferation of activated antitumor pmel-1 cells in a variety of peripheral tissues, including lymph nodes, liver, spleen, and lungs, but not peripheral blood. Most importantly, evidence for T cell function, as measured by production of IFN-gamma, release of perforin, and activation of caspase-3 in target cells, was confined to Ag-expressing tumor. We thus conclude that CD8(+) T cell-mediated destruction of tumor is the result of specific T cell triggering at the tumor site. The ability to induce ubiquitous homing and specific tumor destruction may be important in the case of noninflammatory metastatic tumor foci. 相似文献
23.
Natural variants of AtHKT1 enhance Na+ accumulation in two wild populations of Arabidopsis
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Plants are sessile and therefore have developed mechanisms to adapt to their environment, including the soil mineral nutrient composition. Ionomics is a developing functional genomic strategy designed to rapidly identify the genes and gene networks involved in regulating how plants acquire and accumulate these mineral nutrients from the soil. Here, we report on the coupling of high-throughput elemental profiling of shoot tissue from various Arabidopsis accessions with DNA microarray-based bulk segregant analysis and reverse genetics, for the rapid identification of genes from wild populations of Arabidopsis that are involved in regulating how plants acquire and accumulate Na(+) from the soil. Elemental profiling of shoot tissue from 12 different Arabidopsis accessions revealed that two coastal populations of Arabidopsis collected from Tossa del Mar, Spain, and Tsu, Japan (Ts-1 and Tsu-1, respectively), accumulate higher shoot levels of Na(+) than do Col-0 and other accessions. We identify AtHKT1, known to encode a Na(+) transporter, as being the causal locus driving elevated shoot Na(+) in both Ts-1 and Tsu-1. Furthermore, we establish that a deletion in a tandem repeat sequence approximately 5 kb upstream of AtHKT1 is responsible for the reduced root expression of AtHKT1 observed in these accessions. Reciprocal grafting experiments establish that this loss of AtHKT1 expression in roots is responsible for elevated shoot Na(+). Interestingly, and in contrast to the hkt1-1 null mutant, under NaCl stress conditions, this novel AtHKT1 allele not only does not confer NaCl sensitivity but also cosegregates with elevated NaCl tolerance. We also present all our elemental profiling data in a new open access ionomics database, the Purdue Ionomics Information Management System (PiiMS; http://www.purdue.edu/dp/ionomics). Using DNA microarray-based genotyping has allowed us to rapidly identify AtHKT1 as the casual locus driving the natural variation in shoot Na(+) accumulation we observed in Ts-1 and Tsu-1. Such an approach overcomes the limitations imposed by a lack of established genetic markers in most Arabidopsis accessions and opens up a vast and tractable source of natural variation for the identification of gene function not only in ionomics but also in many other biological processes. 相似文献
24.
25.
Tropea KA Leder E Aslam M Lau AN Raiser DM Lee JH Balasubramaniam V Fredenburgh LE Alex Mitsialis S Kourembanas S Kim CF 《American journal of physiology. Lung cellular and molecular physiology》2012,302(9):L829-L837
Bronchopulmonary dysplasia (BPD) remains a major complication of prematurity resulting in significant morbidity and mortality. The pathology of BPD is multifactorial and leads to alveolar simplification and distal lung injury. Previous studies have shown a beneficial effect of systemic treatment with bone marrow-derived mesenchymal stromal cells (MSCs) and MSC-conditioned media (MSC-CM) leading to amelioration of the lung parenchymal and vascular injury in vivo in the hyperoxia murine model of BPD. It is possible that the beneficial response from the MSCs is at least in part due to activation of endogenous lung epithelial stem cells. Bronchioalveolar stem cells (BASCs) are an adult lung stem cell population capable of self-renewal and differentiation in culture, and BASCs proliferate in response to bronchiolar and alveolar lung injury in vivo. Systemic treatment of neonatal hyperoxia-exposed mice with MSCs or MSC-CM led to a significant increase in BASCs compared with untreated controls. Treatment of BASCs with MSC-CM in culture showed an increase in growth efficiency, indicating a direct effect of MSCs on BASCs. Lineage tracing data in bleomycin-treated adult mice showed that Clara cell secretory protein-expressing cells including BASCs are capable of contributing to alveolar repair after lung injury. MSCs and MSC-derived factors may stimulate BASCs to play a role in the repair of alveolar lung injury found in BPD and in the restoration of distal lung cell epithelia. This work highlights the potential important role of endogenous lung stem cells in the repair of chronic lung diseases. 相似文献
26.
Copeland R Balasubramaniam A Tiwari V Zhang F Bridges A Linhardt RJ Shukla D Liu J 《Biochemistry》2008,47(21):5774-5783
Heparan sulfate (HS) is a highly sulfated polysaccharide and is present in large quantities on the cell surface and in the extracellular matrix. Herpes simplex virus type 1 (HSV-1) utilizes a specialized cell surface HS, known as 3-O-sulfated HS, as an entry receptor to establish infection. Here, we exploit an approach to inhibiting HSV-1 infection by using a 3-O-sulfated octasaccharide, mimicking the active domain of the entry receptor. The 3-O-sulfated octasaccharide was synthesized by incubating a heparin octasaccharide (3-OH octasaccharide) with HS 3-O-sulfotransferase isoform 3. The resultant 3-O-sulfated octasaccharide has a structure of Delta UA2S-GlcNS6S-IdoUA2S-GlcNS6S-IdoUA2S-GlcNS3S6S-IdoUA2S-GlcNS6S (where Delta UA is 4-deoxy-alpha-L-threo-hex-4-enopyranosyluronic acid, GlcN is D-glucosamine, and IdoUA is L-iduronic acid). Results from cell-based assays revealed that the 3-O-sulfated octasaccharide has stronger activity in blocking HSV-1 infection than that of the 3-OH octasaccharide, suggesting that the inhibition of HSV-1 infection requires a unique sulfation moiety. Our results suggest the feasibility of inhibiting HSV-1 infection by blocking viral entry with a specific oligosaccharide. 相似文献
27.
World Journal of Microbiology and Biotechnology - 相似文献
28.
C D Mathew K Balasubramaniam 《Indian journal of biochemistry & biophysics》1987,24(5):suppl 29-suppl 32
29.
Characterization of aPY-like peptides in anglerfish brain using a novel radioimmunoassay for aPY-Gly 总被引:1,自引:0,他引:1
Anglerfish peptide YG (aPY) was isolated from pancreatic islets of the anglerfish. Subsequent immunohistochemical and biochemical analyses demonstrated that anglerfish islet cells synthesize aPY. We have now developed and characterized a radioimmunoassay (RIA) for aPY and have examined extracts of anglerfish brain for aPY-like peptides. Brain extracts were subjected to gel filtration and high performance liquid chromatography (HPLC). Fractions from HPLC eluates were analyzed in the aPY RIA and also in a neuropeptide Y (NPY) RIA. A single peak of aPY-like immunoreactivity eluted from HPLC columns. The elution position of this aPY-like peptide coincided exactly with the aPY-Gly marker under several gradient conditions. Results from the NPY RIA confirmed the presence of several molecular forms of NPY-like immunoreactive peptides in the anglerfish brain. These results demonstrate the utility of the newly developed aPY RIA for studies of anglerfish brain peptides and extend our previous immunohistochemical demonstration of aPY-like staining in the anglerfish brain. 相似文献
30.
Amylin, a 37-residue polypeptide with a single disulfide bond originally isolated from the pancreas of type-II diabetic patients, has been shown to cause peripheral insulin resistance and to attenuate the inhibition of hepatic glucose output by insulin. We have also shown that amylin is present in the rat hypothalamus and that it inhibits food intake by rats. In order to further investigate the anorectic properties we synthesized both human and rat amylin by the solid phase method and purified to homogeneity in an overall yield of 10-20%. Structural analyses indicated that human amylin exhibited predominantly a beta-sheet structure at both acidic and alkaline pH, whereas no ordered structure was evident in the case of rat amylin. Intrahypothalamic injection of rat amylin resulted in a potent dose-dependent inhibitory effect on the food intake by rats adapted to eat their daily ration of food in an eight-hour period. Human amylin was less effective as an anorectic agent. Furthermore, rat amylin completely blocked the potent orexigenic effect of neuropeptide Y (NPY). These investigations show that there is a fundamental difference in the secondary structures of human and rat amylin and that rat amylin is a potent inhibitor of both basal and NPY-induced feeding by rats. 相似文献