Activation of Tax protein by c-Jun-N-terminal kinase is not dependent on the presence or absence of the early growth response-1 gene product

  • Authors:
    • Eduardo Parra
    • Luís Gutierréz
    • Jorge Ferreira
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  • Published online on: November 16, 2015     https://doi.org/10.3892/or.2015.4424
  • Pages: 1163-1169
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Abstract

The Tax protein of human T cell leukemia virus type 1 plays a major role in the pathogenesis of adult T cell leukemia (ATL), an aggressive neoplasia of CD4+ T cells. In the present study, we investigated whether the EGR-1 pathway is involved in the regulation of Tax-induced JNK expression in human Jurkat T cells transfected to express the Tax protein in the presence or absence of PMA or ionomycin. Overexpression of EGR-1 in Jurkat cells transfected to express Tax, promoted the activation of several genes, with the most potent being those that contained AP-1 (Jun/c-Fos), whereas knockdown of endogenous EGR-1 by small interfering RNA (siRNA) somewhat reduced Tax-mediated JNK-1 transcription. Additionally, luciferase-based AP-1 and NF-κB reporter gene assays demonstrated that inhibition of EGR-1 expression by an siRNA did not affect the transcriptional activity of a consensus sequence of either AP-1 or NF-κB. On the other hand, the apoptosis assay, using all-trans retinoic acid (ATRA) as an inducer of apoptosis, confirmed that siRNA against EGR-1 failed to suppress ATRA-induced apoptosis in Jurkat and Jurkat-Tax cells, as noted by the low levels of both DEVDase activity and DNA fragmentation, indicating that the induction of apoptosis by ATRA was Egr-1-independent. Finally, our data showed that activation of Tax by JNK-1 was not dependent on the EGR-1 cascade of events, suggesting that EGR-1 is important but not a determinant for the activity for Tax-induced proliferation of Jurkat cells.
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February-2016
Volume 35 Issue 2

Print ISSN: 1021-335X
Online ISSN:1791-2431

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Spandidos Publications style
Parra E, Gutierréz L and Ferreira J: Activation of Tax protein by c-Jun-N-terminal kinase is not dependent on the presence or absence of the early growth response-1 gene product. Oncol Rep 35: 1163-1169, 2016
APA
Parra, E., Gutierréz, L., & Ferreira, J. (2016). Activation of Tax protein by c-Jun-N-terminal kinase is not dependent on the presence or absence of the early growth response-1 gene product. Oncology Reports, 35, 1163-1169. https://doi.org/10.3892/or.2015.4424
MLA
Parra, E., Gutierréz, L., Ferreira, J."Activation of Tax protein by c-Jun-N-terminal kinase is not dependent on the presence or absence of the early growth response-1 gene product". Oncology Reports 35.2 (2016): 1163-1169.
Chicago
Parra, E., Gutierréz, L., Ferreira, J."Activation of Tax protein by c-Jun-N-terminal kinase is not dependent on the presence or absence of the early growth response-1 gene product". Oncology Reports 35, no. 2 (2016): 1163-1169. https://doi.org/10.3892/or.2015.4424