RESUMO
Nutritional selenium deficiency is associated with Keshan disease in humans and white muscle disease in ruminant livestock. In this study, mice were fed a selenium-deficient diet for three generations. Female mice from the third depleted generation of these mice were given water containing either no added selenium or 0.1 or 1.0 ppm selenium as sodium selenate; DNA microarrays were used to compare gene expression in the muscle from mice fed the selenium diets to that from mice remaining on the depleted diet. The most prominent expression increases were observed with Ptger2 (a prostaglandin E receptor), Tcrb-V13 (a T-cell receptor beta), Tcf-7 (a T-cell transcription factor), and Lck (lymphocyte protein tyrosine kinase), and the major consistent decrease was Vav2, an oncogene in mice consuming the selenium containing diets.
Assuntos
Regulação da Expressão Gênica/efeitos dos fármacos , Análise de Sequência com Séries de Oligonucleotídeos , Selênio/administração & dosagem , Selênio/deficiência , Animais , DNA/análise , DNA/metabolismo , Suplementos Nutricionais , Feminino , Fator 1-alfa Nuclear de Hepatócito , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/biossíntese , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/genética , Camundongos , Camundongos Endogâmicos , Músculo Esquelético/metabolismo , Proteínas Proto-Oncogênicas c-vav/biossíntese , Proteínas Proto-Oncogênicas c-vav/genética , Receptores de Antígenos de Linfócitos T alfa-beta/biossíntese , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Receptores de Prostaglandina E/biossíntese , Receptores de Prostaglandina E/genética , Selênio/farmacologia , Fator 1 de Transcrição de Linfócitos T/biossíntese , Fator 1 de Transcrição de Linfócitos T/genética , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genéticaRESUMO
The proximal promoter of lck directs gene expression exclusively in T cells. To investigate the developmental regulation of the lck proximal promoter activity and its relationship to T cell lineage commitment, a green fluorescence protein (GFP) transgenic (Tg) mouse in which the GFP expression is under the control of the proximal promoter of lck was created. In the adult GFP-Tg mice, >90% of CD4(+)CD8(+) and CD4(+)CD8(-) thymocytes, and the majority of CD4(-)CD8(+) and CD4(-)CD8(-) [double-negative (DN)] thymocytes were highly positive for GFP. Slightly lower but substantial levels of expression of GFP was also observed in mature splenic T cells. No GFP(+) cells was detected in non-T lineage subsets, including mature and immature B cells, CD5(+) B cells, and NK cells, indicating a preserved tissue specificity of the promoter. The earliest GFP(+) cells detected were found in the CD44(+)CD25(-) DN thymocyte subpopulation. The developmental potential of GFP(-) and GFP(+) cells in the CD44(+)CD25(-) DN fraction was examined using in vitro culture systems. The generation of substantial numbers of alphabeta and gammadelta T cells as well as NK cells was demonstrated from both GFP(-) and GFP(+) cells. However, no development of B cells or dendritic cells was detected from GFP(+) CD44(+)CD25(-) DN thymocytes. These results suggest that the progenitors expressing lck proximal promoter activity in the CD44(+)CD25(-) DN thymocyte subset have lost most of the progenitor potential for the B and dendritic cell lineage. Thus, progression of T cell lineage restriction in the earliest thymic population can be visualized by lck proximal promoter activity, suggesting a potential role of Lck in the T cell lineage commitment.
Assuntos
Proteína Tirosina Quinase p56(lck) Linfócito-Específica/biossíntese , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/genética , Regiões Promotoras Genéticas/imunologia , Subpopulações de Linfócitos T/enzimologia , Subpopulações de Linfócitos T/imunologia , Timo/citologia , Timo/enzimologia , Animais , Linfócitos B/citologia , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Células Cultivadas , Células Dendríticas/citologia , Regulação da Expressão Gênica/imunologia , Proteínas de Fluorescência Verde , Receptores de Hialuronatos/biossíntese , Células Matadoras Naturais/citologia , Células Matadoras Naturais/metabolismo , Proteínas Luminescentes/biossíntese , Proteínas Luminescentes/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Confocal , Receptores de Antígenos de Linfócitos T alfa-beta/biossíntese , Receptores de Antígenos de Linfócitos T gama-delta/biossíntese , Receptores de Interleucina-2/biossíntese , Cifozoários , Baço/imunologia , Baço/metabolismo , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/metabolismo , Timo/crescimento & desenvolvimento , Timo/imunologiaRESUMO
CD20 is a B cell surface protein which can initiate intracellular signals involving tyrosine kinase activation, and modify B cell growth and differentiation. CD20 is tightly associated with the Src-family kinases Lyn, Fyn and Lck; however, the mechanism of interaction remains to be determined. Association between CD20 and Src-family kinases has been detected in peripheral blood B cells and in 5 out of 8 unrelated B cell lines. The lack of CD20-associated kinase activity in some cell lines offered an opportunity to investigate the mechanism of CD20 associations. All 8 B cell lines were found to express Lyn, and, with one exception, all cell lines also expressed Fyn. Lck, however, was not detected in any of the cell lines in which CD20 failed to coprecipitate kinase activity. To test the possibility that Lck was required for assembly of the CD20 complex, Lck was transfected into one of the 3 CD20/kinase association-deficient lines, namely T51. CD20 did not coprecipitate kinase activity from the transfected T51 cells, despite their expression of high levels of exogenous Lck, as well as endogenous Lyn and Fyn. CD20 cDNA from T51 was sequenced and found to be normal. These data establish that association between CD20 and Src-family kinases requires an additional factor.