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JunD/AP-1-mediated gene expression promotes lymphocyte growth dependent on interleukin-7 signal transduction.

ABSTRACT: Interleukin-7 (IL-7) is an essential cytokine for lymphocyte growth that has the potential for promoting immune reconstitution. This feature makes IL-7 an ideal candidate for therapeutic development. As with other cytokines, signaling through the IL-7 receptor induces the JAK/STAT pathway. However, the broad scope of IL-7 regulatory targets likely necessitates the use of other signaling components whose identities remain poorly defined. To this end, we used an IL-7 dependent T-cell line to examine how expression of the glycolytic enzyme, Hexokinase II (HXKII) was regulated by IL-7 in a STAT5-independent manner. Our studies revealed that IL-7 promoted the activity of JNK (Jun N-terminal Kinase), and that JNK, in turn, drove the expression of JunD, a component of the Activating Protein 1 (AP-1) transcription factors. Gel shifts showed that the AP-1 complex induced by IL-7 contained JunD but not c-Fos or c-Jun. Inhibition of JNK/JunD blocked glucose uptake and HXKII gene expression, indicating that this pathway was responsible for promoting HXKII expression. Because others had shown that JunD was a negative regulator of cell growth, we performed a bioinformatics analysis to uncover possible JunD-regulated gene targets. Our search revealed that JunD could control the expression of proteins involved in signal transduction, cell survival and metabolism. One of these growth promoters was the oncogene, Pim-1. Pim-1 is an IL-7-induced protein that was inhibited when the activities of JNK or JunD were blocked, showing that in IL-7 dependent T-cells JunD can promote positive signals transduced through Pim-1. This was confirmed when the IL-7-induced proliferation of CD8 T-cells was impaired upon JunD inhibition. These results show that engagement of the IL-7 receptor drives a signal that is more complex than the JAK/STAT pathway, activating JNK and JunD to induce rapid growth stimulation through the expression of metabolic and signaling factors like HXKII and Pim-1.

SUBMITTER: Ruppert SM

PROVIDER: S-EPMC3285677 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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JunD/AP-1-mediated gene expression promotes lymphocyte growth dependent on interleukin-7 signal transduction.

Ruppert Shannon M SM Chehtane Mounir M Zhang Ge G Hu Haiyan H Li Xiaoman X Khaled Annette R AR

PloS one 20120223 2

Interleukin-7 (IL-7) is an essential cytokine for lymphocyte growth that has the potential for promoting immune reconstitution. This feature makes IL-7 an ideal candidate for therapeutic development. As with other cytokines, signaling through the IL-7 receptor induces the JAK/STAT pathway. However, the broad scope of IL-7 regulatory targets likely necessitates the use of other signaling components whose identities remain poorly defined. To this end, we used an IL-7 dependent T-cell line to exami ...[more]

PMID: 22384197

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Project description:BACKGROUND:Previously, we have demonstrated that Interleukin 13 receptor alpha 2 (IL-13R?2) is overexpressed in approximate 78% Glioblastoma multiforme (GBM) samples. We have also demonstrated that IL-13R?2 can serve as a target for cancer immunotherapy in several pre-clinical and clinical studies. However, the significance of overexpression of IL-13R?2 in GBM and astrocytoma and signaling through these receptors is not known. IL-13 can signal through IL-13R via JAK/STAT and AP-1 pathways in certain cell lines including some tumor cell lines. Herein, we have investigated a role of IL-13/IL-13R?2 axis in signaling through AP-1 transcription factors in human glioma samples in situ. METHODS:We examined the activation of AP-1 family of transcription factors (c-Jun, Fra-1, Jun-D, c-Fos, and Jun-B) after treating U251, A172 (IL-13R?2 +ve) and T98G (IL-13R?2 -ve) glioma cell lines with IL-13 by RT-qPCR, and immunocytochemistry (ICC). We also performed colorimetric ELISA based assay to determine AP-1 transcription factor activation in glioma cell lines. Furthermore, we examined the expression of AP-1 transcription factors in situ in GBM and astrocytoma specimens by multiplex-immunohistochemistry (IHC). Student t test and ANOVA were used for statistical analysis of the results. RESULTS:We have demonstrated up-regulation of two AP-1 transcription factors (c-Jun and Fra-1) at mRNA and protein levels upon treatment with IL-13 in IL-13R?2 positive but not in IL-13R?2 negative glioma cell lines. Both transcription factors were also overexpressed in patient derived GBM specimens, however, in contrast to GBM cell lines, c-Fos is also overexpressed in patient derived specimens. Astrocytoma specimens showed lesser extent of immunostaining for IL-13R?2 and three AP-1 factors compared to GBM specimens. By transcription factor activation assay, we demonstrated that AP-1 transcription factors (C-Jun and Fra-1) were activated upon treatment of IL-13R?2?+?GBM cell lines but not IL-13R?2?-?GBM cell line with IL-13. Our results demonstrate functional activity of AP-1 transcription factor in GBM cell lines in response to IL-13. CONCLUSIONS:These results indicate that IL-13/IL-13R?2 axis can mediate signal transduction in situ via AP-1 pathway in GBM and astrocytoma and may serve as a new target for GBM immunotherapy.

Dataset Information

JunD/AP-1-mediated gene expression promotes lymphocyte growth dependent on interleukin-7 signal transduction.

Publications

JunD/AP-1-mediated gene expression promotes lymphocyte growth dependent on interleukin-7 signal transduction.

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