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991.
Geetanjali KharmatePadmesh S. Rajput Heather L. WattRishi K. Somvanshi Nicole ChaudhariXiaofan Qiu Ujendra Kumar 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2011,1813(6):1172-1189
Epidermal growth factor (EGF) regulates normal and tumor cell proliferation via epidermal growth factor receptor (EGFR) phosphorylation, homo- or heterodimerization and activation of mitogen-activated protein kinases (MAPKs) and PI3K/AKT cell survival pathways. In contrast, SST via activation of five different receptor subtypes inhibits cell proliferation and has been potential target in tumor treatment. To gain further insight for the effect of SSTRs on EGFR activated signaling, we determine the role of SSTR1 and SSTR1/5 in human embryonic kidney (HEK) 293 cells. We here demonstrate that cells transfected with SSTR1 or SSTR1/5 negatively regulates EGF mediated effects attributed to the inhibition of EGFR phosphorylation, MAPKs as well as the cell survival signaling. Furthermore, SSTR effects were significantly enhanced in cells when EGFR was knock down using siRNA or treated with selective antagonist (AG1478). Most importantly, the presence of SSTR in addition to modulating signaling pathways leads to the dissociation of the constitutive and EGF induced heteromeric complex of EGFR/ErbB2. Furthermore, cells cotransfected with SSTR1/5 display pronounced effect of SST on the signaling and dissociation of the EGFR/ErbB2 heteromeric complex than the cells expressing SSTR1 alone. Taken together this study provides the first evidence that the presence of SSTR controls EGF mediated cell survival pathway via dissociation of ErbB heteromeric complex. We propose that the activation of SSTR and blockade of EGFR might serve novel therapeutic approach in inhibition of tumor proliferation. 相似文献
992.
993.
Long SA Rieck M Tatum M Bollyky PL Wu RP Muller I Ho JC Shilling HG Buckner JH 《Journal of immunology (Baltimore, Md. : 1950)》2011,187(7):3511-3520
Low Ag dose promotes induction and persistence of regulatory T cells (Tregs) in mice, yet few studies have addressed the role of Ag dose in the induction of adaptive CD4(+)FOXP3(+) Tregs in humans. To this end, we examined the level of FOXP3 expression in human CD4(+)CD25(-) T cells upon activation with autologous APCs and varying doses of peptide. Ag-specific T cells expressing FOXP3 were identified by flow cytometry using MHC class II tetramer (Tmr). We found an inverse relationship between Ag dose and the frequency of FOXP3(+) cells for both foreign Ag-specific and self Ag-specific T cells. Through studies of FOXP3 locus demethylation and helios expression, we determined that variation in the frequency of Tmr(+)FOXP3(+) T cells was not due to expansion of natural Tregs, but instead, we found that induction, proliferation, and persistence of FOXP3(+) cells was similar in high- and low-dose cultures, whereas proliferation of FOXP3(-) T cells was favored in high Ag dose cultures. The frequency of FOXP3(+) cells positively correlated with suppressive function, indicative of adaptive Treg generation. The frequency of FOXP3(+) cells was maintained with IL-2, but not upon restimulation with Ag. Together, these data suggest that low Ag dose favors the transient generation of human Ag-specific adaptive Tregs over the proliferation of Ag-specific FOXP3(-) effector T cells. These adaptive Tregs could function to reduce ongoing inflammatory responses and promote low-dose tolerance in humans, especially when Ag exposure and tolerance is transient. 相似文献
994.
Due to non-productive infections, mice are not a good model to study some human adenoviruses. However, mice provide an excellent model to study the metabolic effects of human adenovirus, Ad36. Research interest in Ad36 is increasing rapidly, and consequently an increase in the use of mice as a model is anticipated. However, little is known about the transmission potential of Ad36 from infected mice to other laboratory animals or personnel. While underestimating the infectivity could promote inadvertent spread of Ad36, overstating it could drain valuable laboratory resources and animals. Therefore, we determined the duration of infectivity in female C57BL/6J mice that were experimentally infected with human adenoviruses Ad36 or Ad2. Other uninfected mice were co-housed for one week with the experimentally-infected animals, four or eight weeks postinfection. Additionally, uninfected mice were housed in the cages of mice that were infected with Ad36, 12 weeks earlier. The presence of viral DNA in tissues was used to indicate infection of mice. Although experimentally-infected mice harboured viral DNA at least up to 12 weeks, the horizontal transmission of infection was observed in co-housed mice only up to four weeks postinfection. Thus, Ad36-infected mice should be considered potentially infective for eight weeks and appropriate handling and barrier containment should be used. After eight week postinfection, horizontal transmission appears unlikely. This information may provide guidelines for animal handling, and experimental design using Ad36, which may increase safety for laboratory personnel and reduce the number of mice required for experiments. 相似文献
995.
Howarth J Kenny P McDonnell S O'Connor A 《Bioorganic & medicinal chemistry letters》2003,13(16):2693-2697
In the course of our investigation into the use of taxol as a lead compound to design new molecules with anti-cancer activity, we have synthesized four compounds based on protected guanosine coupled to taxol isoserine side-chain analogues. These analogues show in vitro anti-cancer activity against the colon cancer cell line SW480 that their constituent parts do not. 相似文献
996.
Many important relationships amongst kinetoplastids, including the position of trypanosomatids, remain uncertain, with limited taxon sampling of markers other than small subunit ribosomal RNA (SSUrRNA). We report gene sequences for cytosolic heat shock proteins 90 and/or 70 (HSP90, HSP70) from the potentially early-diverging kinetoplastids Ichthyobodo necator and Rhynchobodo sp., and from bodonid clades ‘2’ (Parabodonidae) and ‘3’ (Eubodonidae). Some of the new cytosolic HSP70 sequences represent a distinct paralog family (HSP70-B), which is related to yet another paralog known from trypanosomatids (HSP70-C). The (HSP70-B, HSP70-C) clade seemingly diverged before the separation between kinetoplastids and diplonemids. Protein phylogenies support the basal placement of Ichthyobodo within kinetoplastids. Unexpectedly, Rhynchobodo usually forms the next most basal group, separated from the clade ‘1’ bodonids with which it has been allied. Bootstrap support is often weak, but the possibility that Rhynchobodo represents a separate early-diverging lineage within core kinetoplastids deserves further testing. Trypanosomatids always fall remote from the root of kinetoplastids, forming a specific relationship with bodonid clades 2 (and 3), generally with strong bootstrap support. These protein trees with improved taxon sampling provide the best evidence to date for a ‘late’ emergence of trypanosomatids, contradicting recent SSUrRNA-based proposals for a relatively early divergence of this group. 相似文献
997.
Bacterial genomes have been viewed as collections of genes, with each gene and genome evolving more-or-less independently through the acquisition of mutational changes. This historical view has been overturned by the finding that genomes of even closely-related taxa differ widely in gene content. Yet, genomes are more than ever-shuffling collections of genes. Some genes within a genome are more transient than others, conferring a layer of phenotypic lability over a core of genotypic stability; this core decreases in size as the taxa included become increasingly diverse. In addition, some lineages no longer experience high rates of gene turnover, and gene content alters primarily through slow rates of gene loss. More importantly, the cell and molecular biology of the bacterial cell imposes constraints on chromosome composition, maintaining a stable architecture in the face of gene turnover. As a result, genomes reflect the sum of processes that introduce variability, which is then arbitrated by processes that maintain stability. 相似文献
998.
Chatwin HM Rudling JE Patel D Reale V Evans PD 《Insect biochemistry and molecular biology》2003,33(2):173-184
The cloned Drosophila octopamine/tyramine receptor can be coupled to second messenger pathways in an agonist-specific fashion by the endogenously occurring biogenic amines, octopamine and tyramine, when expressed in Chinese hamster ovary cells. We have mutated to alanine a range of receptor amino acids that could potentially form hydrogen bonds with the beta-hydroxyl group of octopamine based on homologies with alpha- and beta-adrenergic receptor subtypes. After stable expression of the mutant receptors in CHO cells we have compared the ability of octopamine and tyramine to displace [(3)H]yohimbine binding to membrane fractions from the mutant cell lines with their ability to modulate adenylyl cyclase activity in intact cells. The results suggest that none of the mutated amino acids residues, at least in isolation, are likely to be involved in interactions with the beta-hydroxyl group of the octopamine side chain. It is possible that amino acids not mutated in the present study are somehow involved in this interaction. Alternatively, it is also possible that the beta-hydroxyl group of the octopamine side chain is capable of interacting with more than one of the amino acids mutated in the present study. 相似文献
999.
Wilkinson DE Thomas BE Limburg DC Holmes A Sauer H Ross DT Soni R Chen Y Guo H Howorth P Valentine H Spicer D Fuller M Steiner JP Hamilton GS Wu YQ 《Bioorganic & medicinal chemistry》2003,11(22):4815-4825
Nonimmunosuppressant ligands, exemplified by GPI 1046 (1), for the peptidyl-prolyl isomerase FKBP12 have been found to unexpectedly possess powerful neuroprotective and neuroregenerative effects in vitro and in vivo. We have extensively explored the therapeutic utility of FKBP12 ligands based on analogues of proline and pipecolic acid. As part of our ongoing program to explore novel structural classes of FKBP12 ligands, we herein wish to report a new class of FKBP12 ligands containing aza-proline and aza-pipecolic acid analogues. Details of the synthetic studies, together with biological activity will be presented. 相似文献
1000.
Andrea C. Tricco Jesmin Antony Noah M. Ivers Huda M. Ashoor Paul A. Khan Erik Blondal Marco Ghassemi Heather MacDonald Maggie H. Chen Lianne Kark Ezer Sharon E. Straus 《CMAJ》2014,186(15):E568-E578