An octapeptide analogue of HIV gp120 modulates protein tyrosine kinase activity in activated peripheral blood T lymphocytes

D. J. Phipps, P. Reed-Doob, D. K. Macfadden, J. P. Piovesan, Gordon Mills, D. R. Branch

Research output: Contribution to journalArticle

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Abstract

Following infection with HIV, patients exhibit lymphocyte dysfunction before the loss of CD4+ T cells. The major HIV surface glycoprotein, gp120, can modulate lymphocyte function in vitro; however, the mechanism by which gp120 affects T lymphocyte signal transduction is controversial. We have used Peptide T, a synthetic octapeptide derived from a conserved, CD4 binding region of gp120, to examine gp120-related modulation of lymphocyte signal transduction. Activation of lymphocytes through the T cell receptor (TCR) in collaboration with cell surface accessory molecules results in rapid increases in tyrosine phosphorylation, probably through the recruitment and activation of src-family protein tyrosine kinases (PTK) such as lck and fyn which have been implicated in mediating the proximal signalling events mediated through the TCR. To identify potential mechanisms by which gp120 could modulate the function of T lymphocytes, we determined the effect of Peptide T on normal, activated peripheral blood lymphoblasts. Treatment of normal, activated peripheral blood lymphoblasts with Peptide T (10-9 M) for 60 min transiently reduced levels of protein tyrosine phosphorylation (ptyr). Reduction in levels of cellular ptyr was associated with transient inhibition of the activity of total cellular and CD4-associated p56(lck) kinase activity (80%). Peptide T also induced a small delayed reduction in the p59(fyn) activity (up to 42%). Despite the decrease in total cellular ptyr levels, pp60(c-src) kinase activity was increased 11-fold following treatment with Peptide T. Peptide T pretreatment also induced tyrosine phosphorylation of a 48-kD CD4-associated protein, indicating that Peptide T may have multiple effects. Peptide T did not alter the levels of total cellular p56(lck) enzyme, nor did it directly inhibit the activity of purified p56(lck). These results are consistent with a Peptide T-dependent modulation of PTK regulation, and support the potential of gp120 to interfere with T lymphocyte signal transduction in activated T lymphocytes.

Original languageEnglish (US)
Pages (from-to)412-418
Number of pages7
JournalClinical and Experimental Immunology
Volume100
Issue number3
StatePublished - Jan 1 1995
Externally publishedYes

Fingerprint

HIV Envelope Protein gp120
Peptide T
Protein-Tyrosine Kinases
T-Lymphocytes
Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
Tyrosine
Phosphorylation
Signal Transduction
src-Family Kinases
Lymphocytes
T-Cell Antigen Receptor
Proteins
Proto-Oncogene Proteins pp60(c-src)
Membrane Glycoproteins
Lymphocyte Activation
HIV Infections
HIV

Keywords

  • gp120
  • HIV
  • peptide T
  • T cells

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

Cite this

An octapeptide analogue of HIV gp120 modulates protein tyrosine kinase activity in activated peripheral blood T lymphocytes. / Phipps, D. J.; Reed-Doob, P.; Macfadden, D. K.; Piovesan, J. P.; Mills, Gordon; Branch, D. R.

In: Clinical and Experimental Immunology, Vol. 100, No. 3, 01.01.1995, p. 412-418.

Research output: Contribution to journalArticle

Phipps, D. J. ; Reed-Doob, P. ; Macfadden, D. K. ; Piovesan, J. P. ; Mills, Gordon ; Branch, D. R. / An octapeptide analogue of HIV gp120 modulates protein tyrosine kinase activity in activated peripheral blood T lymphocytes. In: Clinical and Experimental Immunology. 1995 ; Vol. 100, No. 3. pp. 412-418.
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