Genistein elicits biphasic effects on L-type Ca<sup>2+</sup>current in feline atrial myocytes

Wang, Yong G.; Lipsius, Stephen L.

doi:10.1152/ajpheart.1998.275.1.h204

Cited by 23 publications

(31 citation statements)

References 37 publications

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“…Even though an active and direct participation of TKs in L-type Ca 2ϩ channel function in different tissues was demonstrated (29,38,49,52), less is known about VDCC regulation through tyrosine phosphorylation in GH3 cells. Cataldi et al (5) showed that TK inhibition reduced L-type Ca 2ϩ channel activity evoked by 55 mM K ϩ in GH3 cells.…”

Section: Discussionmentioning

confidence: 99%

Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells

Vela

Pérez-Millán²,

Becú-Villalobos³

et al. 2007

American Journal of Physiology-Cell Physiology

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The L-type Ca2+ channel is the primary voltage-dependent Ca2+-influx pathway in many excitable and secretory cells, and direct phosphorylation by different kinases is one of the mechanisms involved in the regulation of its activity. The aim of this study was to evaluate the participation of Ser/Thr kinases and tyrosine kinases (TKs) in depolarization-induced Ca2+ influx in the endocrine somatomammotrope cell line GH3. Intracellular Ca2+ concentration ([Ca2+]i) was measured using a spectrofluorometric method with fura 2-AM, and 12.5 mM KCl (K+) was used as a depolarization stimulus. K+ induced an abrupt spike (peak) in [Ca2+]i that was abolished in the presence of nifedipine, showing that K+ enhances [Ca2+]i, preferably activating L-type Ca2+ channels. H89, a selective PKA inhibitor, significantly reduced depolarization-induced Ca2+ mobilization in a concentration-related manner when it was applied before or after K+, and okadaic acid, an inhibitor of Ser/Thr phosphatases, which has been shown to regulate PKA-stimulated L-type Ca2+ channels, increased K+-induced Ca2+ entry. When PKC was activated by PMA, the K+-evoked peak in [Ca2+]i, as well as the plateau phase, was significantly reduced, and chelerythrine (a PKC inhibitor) potentiated the K+-induced increase in [Ca2+]i, indicating an inhibitory role of PKC in voltage-dependent Ca2+ channel (VDCC) activity. Genistein, a TK inhibitor, reduced the K+-evoked increase in [Ca2+]i, but, unexpectedly, the tyrosine phosphatase inhibitor orthovanadate reduced not only basal Ca2+ levels but, also, Ca2+ influx during the plateau phase. Both results suggest that different TKs may act differentially on VDCC activation. Activation of receptor TKs with epidermal growth factor (EGF) or vascular endothelial growth factor potentiated K+-induced Ca2+ influx, and AG-1478 (an EGF receptor inhibitor) decreased it. However, inhibition of the non-receptor TK pp60 c-Src enhanced K+-induced Ca2+ influx. The present study strongly demonstrates that a complex equilibrium among different kinases and phosphatases regulates VDCC activity in the pituitary cell line GH3: PKA and receptor TKs, such as vascular endothelial growth factor receptor and EGF receptor, enhance depolarization-induced Ca2+ influx, whereas PKC and c-Src have an inhibitory effect. These kinases modulate membrane depolarization and may therefore participate in the regulation of a plethora of intracellular processes, such as hormone secretion, gene expression, protein synthesis, and cell proliferation, in pituitary cells.

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Section: Discussionmentioning

confidence: 99%

Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells

Vela

Pérez-Millán²,

Becú-Villalobos³

et al. 2007

American Journal of Physiology-Cell Physiology

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“…Previous studies have demonstrated that the inhibition of tyrosine phosphatase activity by vanadate derivatives has little or no effect on the basal L-type Ca 2 þ current in cardiac myocytes (Wang & Lipsius, 1998;Ogura et al, 1999;Sims et al, 2000;Belevych et al, 2001). On the other hand, inhibition of tyrosine phosphatase activity by PAO, an arsenicbased compound, has been reported to regulate the basal L-type Ca 2 þ channel activity in vascular smooth muscle cells and neurons (Pafford et al, 1995;Wijetunge et al, 1998).…”

Section: Pao Transiently Stimulates the Basal L-type Ca 2 þ Channel Amentioning

confidence: 99%

“…It has been established that this type of regulation involves the production of cAMP and subsequent phosphorylation by protein kinase A (PKA). Tyrosine kinases have also been reported to modulate the activity of cardiac ion channels (Shuba & McDonald, 1997;Zhou et al, 1997;Wang & Lipsius, 1998;Hool et al, 1998;Maier et al, 1999;Mason et al, 2002;Tiran et al, 2003). We previously demonstrated that genistein, a tyrosine kinase inhibitor, can increase the sensitivity of cardiac ion channels to b 1 -AR stimulation, suggesting that basal tyrosine kinase activity inhibits badrenergic responsiveness in cardiac myocytes (Hool et al, 1998).…”

Section: Introductionmentioning

confidence: 98%

Redox modulation of basal and β‐adrenergically stimulated cardiac L‐type Ca²⁺ channel activity by phenylarsine oxide

Sims

Harvey

2004

British J Pharmacology

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1 Phenylarsine oxide (PAO) is commonly used to inhibit tyrosine phosphatase activity. However, PAO can affect a variety of different processes because of its ability to promote sulfhydryl oxidation. In the present study, we investigated the effects that PAO has on basal and b-adrenergically stimulated L-type Ca 2 þ channel activity in isolated cardiac myocytes. 2 Extracellular application of PAO transiently stimulated the basal L-type Ca 2 þ channel activity, whereas it irreversibly inhibited protein kinase A (PKA)-dependent regulation of channel activity by isoproterenol, forskolin and 8-CPT-cAMP (8-p-chlorophenylthioadenosine 3 0 ,5 0 -cyclic monophosphate). PAO also inhibited channel activity irreversibly stimulated in the presence of adenosine 5 0 -(3-thiotriphosphate) tetralithium salt. 3 Neither the stimulatory nor the inhibitory effects of PAO were affected by the tyrosine kinase inhibitor lavendustin A, suggesting that tyrosine phosphorylation is not involved. 4 Extracellular application of the sulfhydryl-reducing agent dithiothreitol (DTT) antagonized both the stimulatory and inhibitory effects of PAO. Yet, following intracellular dialysis with DTT, only the inhibitory effect of PAO was antagonized. 5 The inhibitory effect of PAO was mimicked by intracellular, but not extracellular application of the membrane impermeant thiol oxidant 5,5 0 -dithio-bis(2-nitrobenzoic acid).6 These results suggest that the stimulatory effect of PAO results from oxidation of sulfhydryl residues at an extracelluar site and the inhibitory effect is due to redox regulation of an intracellular site that affects the response of the channel to PKA-dependent phosphorylation. It is concluded that the redox state of the cell may play a critical role in modulating b-adrenergic responsiveness of the Ltype Ca 2 þ channel in cardiac myocytes.

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“…Furthermore, IGF-1 failed to produce an effect on the L-type Ca 2ϩ current in ventricular myocytes (Sims et al, 2000). On the other hand, the ability of genistein to inhibit the basal L-type Ca 2ϩ current in a variety of cardiac myocytes has been used as an argument to support the idea that these channels may be actually regulated by basal tyrosine kinase activity (Yokoshiki et al, 1996;Hool et al, 1998;Katsube et al, 1998;Wang and Lipsius, 1998;Ogura et al, 1999). Although genistein inhibits PTK activity with little or no effect on serine/threonine protein kinases, it can also produce effects that are unrelated to its ability to inhibit This work was supported by grants from the National Institutes of Health (AG16658 and HL68170).…”

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confidence: 99%

Genistein Inhibits Cardiac L-Type Ca²⁺Channel Activity by a Tyrosine Kinase-Independent Mechanism

2002

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It has been suggested that protein tyrosine kinase (PTK) activity can directly regulate cardiac L-type Ca 2ϩ channels. This conclusion is based to a large extent on the observation that the PTK inhibitor genistein can inhibit the cardiac L-type Ca 2ϩ current. The purpose of the present study was to determine whether the ability of genistein to inhibit cardiac L-type Ca 2ϩ channel activity is due to inhibition of PTK activity. Genistein significantly reduced the magnitude of the L-type Ca 2ϩ current in guinea pig ventricular myocytes recorded using the wholecell patch-clamp technique. However, this effect was associated with extracellular, not intracellular, application of the drug. Peroxovanadate (PVN), a potent protein tyrosine phosphatase inhibitor, had no effect on the basal Ca 2ϩ current. PVN was also ineffective in preventing the inhibitory effect of genistein. Internal perfusion of cells with a pipette solution containing ATP␥S was used to prevent reversibility of phosphorylation-dependent processes. This treatment did not alter the inhibitory effect of genistein, although it did result in irreversible protein kinase A-dependent regulation of the Ca 2ϩ current. Bath application of lavendustin A, a PTK inhibitor that is structurally unrelated to genistein, did not affect the Ca 2ϩ current amplitude. The inhibitory effect of genistein was also associated with a hyperpolarizing shift in the voltage dependence of Ca 2ϩ channel inactivation. These results are consistent with the conclusion that the cardiac L-type Ca 2ϩ current is not directly regulated by PTK activity and that the inhibitory effect of genistein is due to direct non-catalytic blockade of the channels.

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Genistein elicits biphasic effects on L-type Ca²⁺current in feline atrial myocytes

Cited by 23 publications

References 37 publications

Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells

Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells

Redox modulation of basal and β‐adrenergically stimulated cardiac L‐type Ca²⁺ channel activity by phenylarsine oxide

Genistein Inhibits Cardiac L-Type Ca²⁺Channel Activity by a Tyrosine Kinase-Independent Mechanism

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Genistein elicits biphasic effects on L-type Ca2+current in feline atrial myocytes

Cited by 23 publications

References 37 publications

Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells

Different kinases regulate activation of voltage-dependent calcium channels by depolarization in GH3 cells

Redox modulation of basal and β‐adrenergically stimulated cardiac L‐type Ca2+ channel activity by phenylarsine oxide

Genistein Inhibits Cardiac L-Type Ca2+Channel Activity by a Tyrosine Kinase-Independent Mechanism

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Genistein elicits biphasic effects on L-type Ca²⁺current in feline atrial myocytes

Redox modulation of basal and β‐adrenergically stimulated cardiac L‐type Ca²⁺ channel activity by phenylarsine oxide

Genistein Inhibits Cardiac L-Type Ca²⁺Channel Activity by a Tyrosine Kinase-Independent Mechanism