[41] Use of vanadate as protein-phosphotyrosine phosphatase inhibitor

Gordon, Julius A.

doi:10.1016/0076-6879(91)01043-2

Cited by 549 publications

(333 citation statements)

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“…It should be pointed out here that even vanadate has no activity on the GR of L929 cells when the stock solutions are not prepared by boiling at pH 10 (data not shown). Thus, it is the monomeric form of vanadate, rather than decavanadate and other oligomeric forms, that is essential for activity-a result that is consistent with the use of these compounds as phosphatase inhibitors [16]. Second, potentiation of GR transactivity occurred both before and after hormone-induced translocation of the GR to the nucleus (Figs.…”

Section: Discussionsupporting

confidence: 63%

“…Instead, we now find that only vanadate that is prepared to yield a high proportion of monomers (Na 3 VO 4 ·nH 2 O) has any effect on the GR of these cells. Although vanadate prepared in this fashion has been used to target various enzymatic activities within cells [16], especially tyrosine phosphatases [17,18], proof that this action requires intracellular entry, rather than a membrane-based signaling event, has not, to our knowledge, been reported. Yet, studies using vanadate to inhibit intracellular phosphatases typically use very high concentrations of this compound (100-500 M), perhaps because it is inefficient in gaining entry into the cell.…”

Section: Discussionmentioning

confidence: 99%

“…This was discovered as part of our efforts to use sodium vanadate to inhibit heat shock factor (HSF1) activity in stressed cells [15]. In that work, HSF1 inactivation was achieved through a mechanism that was consistent with the known ability of vanadate to act as an inhibitor of tyrosine phosphatases [16][17][18], resulting in subsequent inhibition of HSF1 via MAPK (ERK-2)-mediated phoshorylation [19,20]. However, in cells stably-transfected with a GR-responsive CAT reporter, we have observed that vanadate treatment under non-stress conditions greatly increases hormone-induced CAT gene expression.…”

Section: Introductionmentioning

confidence: 94%

“…Vanadate was prepared according to the method of Gordon [16] by dissolving sodium orthovanadate (Na 3 VO 4 ·nH 2 O) to 500 mM in sterile water and adjusting to approximately pH 10. To insure the presence of the active monomers, the vanadate stock solution was heated to boiling until the solution was clear.…”

Section: Cell Culture and Vanadate Treatmentmentioning

confidence: 99%

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Vanadate increases glucocorticoid receptor-mediated gene expression: a novel mechanism for potentiation of a steroid receptor

Calzi

Periyasamy

et al. 2002

The Journal of Steroid Biochemistry and Molecular Biology

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Transition metal oxyanions, such as molybdate, tungstate and vandadate, have been shown to prevent in vitro hormone-induced activation of the glucocorticoid receptor (GR) by blocking dissociation of the GR/heat shock protein heterocomplex. In this work, we report a novel effect of vanadate: in vivo potentiation of GR-mediated gene expression. In cells stably-transfected with complex (mouse mammary tumor virus (MMTV)) or minimal GR-regulated CAT reporters, treatment with 500 M vanadate caused CAT gene expression to dramatically increase, even at saturating concentrations of dexamethasone; while no such effect was seen in response to RU486 antagonist. Similar treatment with molybdate had no effect on GR activity, suggesting that the response to vanadate was not a general property of transition metal oxyanions. Treatment with vanadate after hormone-induced nuclear translocation of the GR also caused potentiation, demonstrating that vanadate was acting on a post-transformation event, perhaps by affecting the transactivation function of DNA-bound GR. Paradoxically, vanadate caused an apparent but temporary "loss" of GR protein immediately after treatment (as measured by loss of reactivity to BuGR2 antibody and of hormone-binding capacity) that returned to normal at approximately 8 h post-treatment, suggesting that potentiation of GR transactivation function (as measured by our CAT assays) was probably occurring during the later stages (8-24 h) of this assay. However, gel shift analyses revealed that vanadate could induce binding of the hormone-free GR to glucocorticoid response element (GRE)-containing oligonucleotides immediately after treatment. Thus, the rapid vanadate-induced "loss" of GR was not due to degradation of GR protein. Yet, vanadate in the absence of hormone had no effect on CAT reporter expression, demonstrating that this form of the GR still requires agonist for its enhanced transcriptional activity. As an indication of the potential mechanism of vanadate action, vanadate was found to dramatically stimulate the mitogen-activated protein kinases, ERK-1 and ERK-2. In addition, vanadate potentiation of GR reporter gene expression was completely blocked by the tyrosine kinase inhibitor herbimycin A. Taken as a whole, our results suggest that vanadate can have dramatic and complex effects on GR structure and function, resulting in hormone-free activation of GR DNA-binding function, as well as alterations to the BuGR2 epitope and hormone-binding domains-while at the same time stimulating tyrosine phosphorylation pathways controlling GR-mediated gene transcription.

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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Section: Cell Culture and Vanadate Treatmentmentioning

confidence: 99%

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Vanadate increases glucocorticoid receptor-mediated gene expression: a novel mechanism for potentiation of a steroid receptor

Calzi

Periyasamy

et al. 2002

The Journal of Steroid Biochemistry and Molecular Biology

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“…Verapamil (SigmaAldrich) was dissolved in water and diluted in the bathing solution. Aqueous stock solutions (100 mM) of Na 3 VO 4 (orthovanadate) (Fisher Scientific, Nepeon, ON, Canada) were freshly prepared, and the pH was adjusted to B10 (Gordon, 1991;Shuba et al, 1996). Appropriate amounts of stock solution were added to the superfusate just before use, and the pH was readjusted to 7.4 with NaOH.…”

Section: Drugsmentioning

confidence: 99%

Cardiac Na⁺–Ca²⁺ exchanger current induced by tyrphostin tyrosine kinase inhibitors

Missan

McDonald

2004

British J Pharmacology

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1 Tyrosine kinase (TK) inhibitors genistein and tyrphostin A23 (A23) inhibited Ca 2 þ currents in guinea-pig ventricular myocytes investigated under standard whole-cell conditions (K þ -free Tyrode's superfusate; EGTA-buffered (pCa-10.5) Cs þ dialysate). However, the inhibitors (100 mM) also induced membrane currents that reversed between À40 and 0 mV, and the objective of the present study was to characterize these currents.2 Genistein-induced current behaved like Cl À current, and was unaffected by either the addition of divalent cations (0.5 mM Cd 2 þ ; 3 mM Ni 2 þ ) that block the Na þ -Ca 2 þ exchanger (NCX), or the removal of external Na þ and Ca 2 þ . 3 A23-induced current was independent of Cl À driving force, and strongly suppressed by addition of Cd 2 þ and Ni 2 þ , and by removal of either external Na þ or Ca 2 þ . These and other results suggested that A23 activated an NCX current driven by submembrane Na þ and Ca 2 þ concentrations higher than those in the bulk cytoplasm. 4 Improved control of intracellular Na þ and Ca 2 þ concentrations was obtained by suppressing cation influx (10 mM verapamil) and raising dialysate Na þ to 7 mM and dialysate pCa to 7. Under these conditions, stimulation by A23 was described by the Hill equation with EC 50 6874 mM and coefficient 1.1, tyrphostin A25 was as effective as A23, and TK-inactive tyrphostin A1 was ineffective. Phosphotyrosyl phosphatase inhibitor orthovanadate (1 mM) antagonized the action of 100 mM A23. 5 The results suggest that activation of cardiac NCX by A23 is due to inhibition of genisteininsensitive TK.

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Okadaic acid, sphingosine, and phorbol ester reversibly modulate heat induction on protein kinase F a /GSK‐3α in A431 cells

Yang¹,

Chang²,

Lee³

1996

J of Cellular Biochemistry

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Exposure of A431 cells to a rapid and sudden increase from 37 degrees C to 46 degrees C for 30 min could induce an increase in protein level and cellular activity of protein (kinase FA/GSK-3 alpha) up to approximately 200% of control level. However, when cells were first treated with 500 nM tumor promoter phorbol ester TPA at 37 degrees C for 30 min to activate cellular protein kinase C (PKC) or with 400 nM okadaic acid at 37 degrees C for 30 min to inhibit cellular protein phosphatases followed by heat shock at 46 degrees C for another 30 min, the heat induction on kinase FA/GSK-3 alpha was found to be completed blocked. In sharp contrast, when cells were first treated with 1 microM TPA at 37 degrees C for 24 h or with 5 microM sphingosine at 37 degrees C for 30 min to down-regulate cellular PKC, the heat induction on kinase FA/GSK-3 alpha was found to be reversely promoted up to approximately 250% of control level, demonstrating that kinase FA/GSK-3 alpha may not represent a constitutively active/mitogen-inactivated protein kinase as previously conceived. Taken together, the results provide initial evidence that TPA/sphingosine and okadaic acid could reversibly modulate the heat induction on kinase FA/GSK-3 alpha in A431 cells, suggesting that phosphorylation/dephosphorylation mechanisms are involved in the regulation of the heat-shock induction of kinase FA/GSK-3 alpha, representing a new mode of signal transduction for the regulation of this multisubstrate protein kinase and a new mode of signaling pathway modulating the heat-induction process.

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[41] Use of vanadate as protein-phosphotyrosine phosphatase inhibitor

Cited by 549 publications

References 27 publications

Vanadate increases glucocorticoid receptor-mediated gene expression: a novel mechanism for potentiation of a steroid receptor

Vanadate increases glucocorticoid receptor-mediated gene expression: a novel mechanism for potentiation of a steroid receptor

Cardiac Na⁺–Ca²⁺ exchanger current induced by tyrphostin tyrosine kinase inhibitors

Okadaic acid, sphingosine, and phorbol ester reversibly modulate heat induction on protein kinase F a /GSK‐3α in A431 cells

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[41] Use of vanadate as protein-phosphotyrosine phosphatase inhibitor

Cited by 549 publications

References 27 publications

Vanadate increases glucocorticoid receptor-mediated gene expression: a novel mechanism for potentiation of a steroid receptor

Vanadate increases glucocorticoid receptor-mediated gene expression: a novel mechanism for potentiation of a steroid receptor

Cardiac Na+–Ca2+ exchanger current induced by tyrphostin tyrosine kinase inhibitors

Okadaic acid, sphingosine, and phorbol ester reversibly modulate heat induction on protein kinase F a /GSK‐3α in A431 cells

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Cardiac Na⁺–Ca²⁺ exchanger current induced by tyrphostin tyrosine kinase inhibitors