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51.
CD4 T cell-dependent autoimmunity against a melanocyte neoantigen induces spontaneous vitiligo and depends upon Fas-Fas ligand interactions 总被引:5,自引:0,他引:5
Lambe T Leung JC Bouriez-Jones T Silver K Makinen K Crockford TL Ferry H Forrester JV Cornall RJ 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(5):3055-3062
Better understanding of tolerance and autoimmunity toward melanocyte-specific Ags is needed to develop effective treatment for vitiligo and malignant melanoma; yet, a systematic assessment of these mechanisms has been hampered by the difficulty in tracking autoreactive T cells. To address this issue, we have generated transgenic mice that express hen egg lysozyme as a melanocyte-specific neoantigen. By crossing these animals to a hen egg lysozyme-specific CD4 TCR transgenic line we have been able to track autoreactive CD4+ T cells from their development in the thymus to their involvement in spontaneous autoimmune disease with striking similarity to human vitiligo vulgaris and Vogt-Koyanagi-Harada syndrome. Our findings show that CD4-dependent destruction of melanocytes is partially inhibited by blocking Fas-Fas ligand interactions and also highlights the importance of local control of autoimmunity, as vitiligo remains patchy and never proceeds to confluence even when Ag and autoreactive CD4+ T cells are abundant. Immune therapy to enhance or suppress melanocyte-specific T cells can be directed at a series of semiredundant pathways involving tolerance and cell death. 相似文献
52.
Expression of Mycobacterium tuberculosis Rv1991c using an arabinose-inducible promoter demonstrates its role as a toxin 总被引:1,自引:0,他引:1
Conditional gene expression systems are useful tools for studying the role of essential or toxic gene products in bacterial systems. There is a paucity of such systems available for use in the mycobacteria. The utility of the Escherichia coli arabinose-inducible system was looked into, since it is tightly controlled in response to the presence of arabinose and glucose. It was demonstrated that the P(BAD) promoter can be used to express heterologous genes in Mycobacterium smegmatis. Expression of a lacZ reporter gene demonstrated that promoter activity was inducible in response to the presence of glucose, but only on solid medium. This system was utilized to study the functional consequences of expressing one member of a putative toxin-antitoxin pair (Rv1991c). Rv1991c has homology with a number of bacterial toxins, including ChpK, MazF and PemK. A potential antitoxin gene has been identified, adjacent to Rv1991c in the genome, which was coexpressed with the toxin. Expression of the toxin alone inhibited the growth of E. coli, whereas coexpression with the antitoxin did not. Expression of Rv1991c also led to a marked reduction of cell viability in M. smegmatis, confirming its role as a potent toxin. 相似文献
53.
Chorismate mutase (CM) catalyzes the rearrangement of chorismate to prephenate in the biosynthetic pathway that forms phenylalanine and tyrosine in bacteria, fungi, plants, and apicomplexan parasites. Since this enzyme is absent from mammals, it represents a promising target for the development of new antimycobacterial drugs, which are needed to combat Mycobacterium tuberculosis, the causative agent of tuberculosis. Until recently, two putative open reading frames (ORFs), Rv0948c and Rv1885c, showing low sequence similarity to CMs have been described as "conserved hypothetical proteins" in the M. tuberculosis genome. However, we and others demonstrated that these ORFs are in fact monofunctional CMs of the AroQ structural class and that they are differentially localized in the mycobacterial cell. Since homologues to the M. tuberculosis enzymes are also present in Mycobacterium smegmatis, we cloned the coding sequences corresponding to ORFs MSMEG5513 and MSMEG2114 from the latter. The CM activities of both ORFs was determined, as well as their translational start sites. In addition, we analyzed the promoter activities of three M. tuberculosis loci related to phenylalanine and tyrosine biosynthesis under a variety of conditions using M. smegmatis as a surrogate host. Our results indicate that the aroQ (Rv0948c), *aroQ (Rv1885c), and fbpB (Rv1886c) genes from M. tuberculosis are constitutively expressed or subjected to minor regulation by aromatic amino acids levels, especially tryptophan. 相似文献
54.
Yvonne J.K. Edwards Klaudia Walter Gayle McEwen Tanya Vavouri Krystyna A. Kelly Irina Abnizova Adam Woolfe Debbie K. Goode Martin Goodson Phil North Phil Snell Heather Callaway Sarah F. Smith Walter R. Gilks Julie E. Cooke Greg Elgar 《Comparative biochemistry and physiology. Part D, Genomics & proteomics》2006,1(1):46
55.
DiDonato M Krishna SS Schwarzenbacher R McMullan D Jaroszewski L Miller MD Abdubek P Agarwalla S Ambing E Axelrod H Biorac T Chiu HJ Deacon AM Elsliger MA Feuerhelm J Godzik A Grittini C Grzechnik SK Hale J Hampton E Haugen J Hornsby M Klock HE Knuth MW Koesema E Kreusch A Kuhn P Lesley SA Moy K Nigoghossian E Okach L Paulsen J Quijano K Reyes R Rife C Spraggon G Stevens RC van den Bedem H Velasquez J White A Wolf G Xu Q Hodgson KO Wooley J Wilson IA 《Proteins》2006,63(1):256-260
56.
57.
Genome Duplications and Other Features in 12 Mb of DNA Sequence from Human Chromosome 16p and 16q 总被引:7,自引:0,他引:7
Brendan J. Loftus Ung-Jin Kim Victoria P. Sneddon Francis Kalush Rhonda Brandon Joyce Fuhrmann Tanya Mason Marie L. Crosby Mary Barnstead Lisa Cronin Anne Deslattes Mays Yicheng Cao Robert X. Xu Hyung-Lyun Kang Steve Mitchell Evan E. Eichler Peter C. Harris J. Craig Venter Mark D. Adams 《Genomics》1999,60(3):295-308
Several publicly funded large-scale sequencing efforts have been initiated with the goal of completing the first reference human genome sequence by the year 2005. Here we present the results of analysis of 11.8 Mb of genomic sequence from chromosome 16. The apparent gene density varies throughout the region, but the number of genes predicted (84) suggests that this is a gene-poor region. This result may also suggest that the total number of human genes is likely to be at the lower end of published estimates. One of the most interesting aspects of this region of the genome is the presence of highly homologous, recently duplicated tracts of sequence distributed throughout the p-arm. Such duplications have implications for mapping and gene analysis as well as the predisposition to recurrent chromosomal structural rearrangements associated with genetic disease. 相似文献
58.
59.
The C. elegans vulva is patterned by epidermal growth factor (EGF) activation of Ras to control 1° fate, and 1° fate induces antagonistic Notch-dependent 2° fate. Furthermore, a spatial EGF gradient, in addition to inducing 1° fate, directly contributes to 2° fate via an unknown pathway. We find that in addition to its canonical effector, Raf, vulval Ras utilizes an exchange factor for the Ral small GTPase (RalGEF), such that Ras-RalGEF-Ral antagonizes Ras-Raf pro-1° fate activity. Consistent with its restricted expression pattern, Ral participates in EGF pro-2° activity. Thus, we have delineated a Ras effector-switching mechanism whereby position within the morphogen gradient dictates that Ras effector usage is switched to RalGEF from Raf to promote 2° instead of 1° fate. Our observations define the utility of Ras effector switching during normal development and may provide a possible mechanistic basis for cell and cancer-type differences in effector dependency and activation. 相似文献
60.
Rudolph MC Russell TD Webb P Neville MC Anderson SM 《American journal of physiology. Endocrinology and metabolism》2011,300(6):E1059-E1068
Prolactin (PRL) is known to play an essential role in mammary alveolar proliferation in the pregnant mouse, but its role in lactation has been more difficult to define. Genetic manipulations that alter expression of the PRL receptor and its downstream signaling molecules resulted in developmental defects that may directly or indirectly impact secretory activation and lactation. To examine the in vivo role of PRL specifically in lactation, bromocriptine (BrCr) was administered every 8 h to lactating mice on the second day postpartum, resulting in an ~95% decrease in serum PRL levels. Although morphological changes in secretory alveoli were slight, by 8 h of BrCr, pup growth was inhibited significantly. Phosphorylated STAT5 fell to undetectable levels within 4 h. Decreased milk protein gene expression, β-casein, and α-lactalbumin, was observed after 8 h of treatment. To assess mammary-specific effects on lipid synthesis genes, we isolated mammary epithelial cells (MECs) depleted of mammary adipocytes. Expression of genes involved in glucose uptake, glycolysis, pentose phosphate shunt, de novo synthesis of fatty acids, and biosynthesis of triacylglycerides was decreased up to 19-fold in MECs by just 8 h of BrCr treatment. Glands from BrCr-treated mice showed a twofold reduction in intracellular cytoplasmic lipid droplets and a reduction in cytosolic β-casein. These data demonstrate that PRL signaling regulates MEC-specific lipogenic gene expression and that PRL signals coordinate the milk synthesis and mammary epithelial cell survival during lactation in the mouse. 相似文献