Extracellular HIV-1 Tat protein differentially activates the JNK and ERK/MAPK pathways in CD4 T cells

Carlo Mischiati, Flavio Pironi, Daniela Milani, Mauro Giacca, Prisco Mirandola, Silvano Capitani, Giorgio Zauli

Research output: Contribution to journalArticle

Abstract

Objective: To investigate the intracellular signals elicited by extracellular HIV-1 Tat protein in lymphoid CD4 T cells. Methods: CD4 Jurkat T cells were treated with a series of glutathione S-transferase (GST)-Tat fusion proteins: full-length two-exon GST-Tat (GST-Tat2E); one-exon Tat, in which the second exon of Tat was deleted (GST-Tat1E); two-exon Tat, in which the seven arginine residues have been changed to alanine residues (GST-TatArg(mut)), GST-TatΔN, which shows a deletion of the N-terminal 21 amino acids. The cells were either treated with soluble GST-Tat proteins or seeded on plates coated with GST-Tat proteins immobilized on plastic. At various time points, Jurkat cells were lysed and examined for c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) activity. Results: Soluble and immobilized GST-Tat2E, but not GST-Tat1E, GST-TatArg(mut) and GST-TatΔN, activated JNK in a dose-dependent manner, induced a rapid phosphorylation of c-Jun on Ser63 and promoted the de novo synthesis of c-Jun protein. Moreover, both GST-Tat2E and GST-Tat1E also stimulated ERK/MAPK. However, the activation of JNK was maximal at concentrations of 100 nM of GST-Tat2E and was blocked by the S6-kinase inhibitor rapamycin, whereas the activation of ERK/MAPK was already maximal at 1 nM of GST-Tat2E and was enhanced by rapamycin. Conclusions: Tat-mediated activation of JNK requires the second exon of Tat, which is dispensable for the activation of ERK/MAPK. The ability to stimulate JNK and ERK/MAPK does not require Tat internalization.

Original languageEnglish
Pages (from-to)1637-1645
Number of pages9
JournalAIDS (London, England)
Volume13
Issue number13
DOIs
Publication statusPublished - 1999

Keywords

  • ERK/MAPK
  • HIV-1
  • JNK
  • Tat

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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  • Cite this

    Mischiati, C., Pironi, F., Milani, D., Giacca, M., Mirandola, P., Capitani, S., & Zauli, G. (1999). Extracellular HIV-1 Tat protein differentially activates the JNK and ERK/MAPK pathways in CD4 T cells. AIDS (London, England), 13(13), 1637-1645. https://doi.org/10.1097/00002030-199909100-00006