Ran overexpression leads to diminished T cell responses and selectively modulates nuclear levels of c-Jun and c-Fos.
Ras-related nuclear protein (Ran) is a Ras family GTPase, and its documented functions are the regulation of DNA replication, cell cycle progression, nuclear structure formation, RNA processing and exportation, and nuclear protein importation. In this study, we performed detailed mapping of Ran expression during mouse ontogeny using in situ hybridization. High Ran expression was found in various organs and tissues including the thymus cortex and spleen white pulp. Ran was induced in T cells 24 h after their activation. The function of Ran in the immune system was investigated using Ran transgenic (Tg) mice. In Ran Tg T cells, there was compromised activation marker expression, lymphokine secretion, and proliferation upon T cell receptor activation in vitro when compared with wild type T cells. Tg mice also manifested defective delayed type hypersensitivity in vivo. Upon PMA and ionomycin stimulation, Tg T cells were defective in nuclear accumulation of AP-1 factors (c-Jun and c-Fos) but not NF-kappaB family members. Our experiments showed that Ran had important regulatory function in T cell activation. One of the possible mechanisms is that intracellular Ran protein levels control the nuclear retention for selective transcription factors such as c-Jun and c-Fos of AP-1, which is known to be critical in T cell activation and proliferation and lymphokine secretion.
Qiao
Xiaoying
X
Laboratory of Immunology, Centre de Recherche, Centre Hospitalier de l'Université de Montréal, Montreal, Quebec H2L 4M1, Canada.
Pham
Diep Ngoc Thi
DN
Luo
Hongyu
H
Wu
Jiangping
J
D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D016762:Genes, fos / Q000276:immunology*; D016758:Genes, jun / Q000276:immunology*; D006968:Hypersensitivity, Delayed / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
D016207:Cytokines; C102460:Ran protein, mouse; D011948:Receptors, Antigen, T-Cell; D018808:Transcription Factor AP-1; D020931:ran GTP-Binding Protein