We studied the effect of protein phosphatase and kinase inhibitors on Tax-mediated transcription of constructs carrying the reporter gene chloramphenicol acetyl transferase under the control of either the full-length LTR of HTLV-I or three copies of the tax-responsive 21-bp repeats. We observed that treatment with okadaic acid, which inhibits the serine/threonine protein phosphatases type 1 and 2A, reduced HTLV-I LTR transcriptional activation in MT2 and K562 cells; on the contrary, the enhancer activity of the 21-bp sequences was significantly increased in both cell lines; treatment with the protein kinase C inhibitor H-7 blocked Tax-mediated transcription of both constructs. We also found that treatment with sodium orthovanadate, a tyrosine phosphatase inhibitor, reduced Tax-mediated activation of both plasmids. These findings indicated that specific serine/threonine phosphorylation events are required for Tax-mediated HTLV-I LTR activation and also suggested that phosphorylation at tyrosine residues is involved in this process.

Tax-induced HTLV-I LTR transcriptional activation is modulated by phosphorylation.

OLIVIERO, Salvatore;
1994-01-01

Abstract

We studied the effect of protein phosphatase and kinase inhibitors on Tax-mediated transcription of constructs carrying the reporter gene chloramphenicol acetyl transferase under the control of either the full-length LTR of HTLV-I or three copies of the tax-responsive 21-bp repeats. We observed that treatment with okadaic acid, which inhibits the serine/threonine protein phosphatases type 1 and 2A, reduced HTLV-I LTR transcriptional activation in MT2 and K562 cells; on the contrary, the enhancer activity of the 21-bp sequences was significantly increased in both cell lines; treatment with the protein kinase C inhibitor H-7 blocked Tax-mediated transcription of both constructs. We also found that treatment with sodium orthovanadate, a tyrosine phosphatase inhibitor, reduced Tax-mediated activation of both plasmids. These findings indicated that specific serine/threonine phosphorylation events are required for Tax-mediated HTLV-I LTR activation and also suggested that phosphorylation at tyrosine residues is involved in this process.
1994
205
666
673
Saggioro D; Forino M; Penzo A; Pesce M; Oliviero S; Chieco-Bianchi L.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/141204
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