Epidermal growth factor (EGF) produces inositol phosphates and increases cytoplasmic free calcium in cultured porcine thyroid cells

Takasu, Nobuyuki; Takasu, Mika; Yamada, Takashi; Shimizu, Yoshifusa

doi:10.1016/0006-291x(88)90626-2

Cited by 27 publications

(8 citation statements)

References 19 publications

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“…The implication of the absent response to noradrenaline is, however, uncertain as a positive effect of this agent on phosphatidylinositol breakdown has not been reported to occur in porcine thyrocytes. However, iodide efflux was also unchanged by EGF, known to activate the Ca2+/phosphatidylinositol cas¬ cade in the same species (26,27). Similar to TPA, EGF has a clear proliferative effect on the filter-cultured monolayers (25).…”

Section: Discussionmentioning

confidence: 94%

Polarized efflux of iodide in porcine thyrocytes occurs via a cAMP-regulated iodide channel in the apical plasma membrane

Nilsson

Björkman

Ekholm

et al. 1992

Acta Endocrinologica

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II, Ekholm R, Ericson LE. Polarized efflux of iodide in porcine thyrocytes occurs via a cAMP-regulated iodide channel in the apical plasma membrane. Acta Endocrinol 1992:126: 67-74.ISSN 0001-5 598The intracellular regulation of thyrotropin-stimulated iodide efflux was studied in polarized porcine thyrocytes grown as a continuous, tight monolayer in bicameral culture chambers. From a previous study using this system we know that thyrotropin rapidly increases iodide efflux in the apical but not basal direction of the polarized epithelium.[125I]-iodide efflux in apical direction was stimulated by thyrotropin in a concentration-dependent manner (1\p=n-\10 U/I), whereas efflux in basal direction was unchanged at any thyrotropin dose. Thyrotropin-induced elevation of intracellular cAMP showed a corresponding concentration dependence. The selective stimulation of apical efflux by thyrotropin was evident also when re-uptake of iodide released in basal direction was blocked by perchlorate. The effect of thyrotropin on apical efflux was mimicked by 8-bromo-cAMP and forskolin, whereas agents known to activate the Ca2 + /phosphatidylinositol cascade (epidermal growth factor) and protein kinase C (phorbol ester) or increase cytosolic [Ca2 + ] (A23187) were inactive. We conclude that the selective stimulation by thyrotropin of apical iodide efflux, corresponding to efflux in luminal direction in intact follicles, occurs via cAMP-regulated iodide channels present in the apical domain of the plasma membrane.The ability of the thyroid to concentrate iodide is essential for the proper synthesis of thyroid hormones. Many studies have detailed the mechanism by which the thyroid follicle cell (thyrocyte) takes up iodide from the tissue interstitium. This process, taking place at the basolateral domain of the plasma membrane (1), is stimulated by TSH; as the stimulation is blocked by inhibitors of protein synthesis (2-4), it probably involves new iodide carrier molecules. Another component in iodide transport is iodide efflux from the thyrocytes. As originally found in vivo in the rat (5) and later demonstrated in vitro in thyroid lobes (6) and slices (7), TSH stimulates, with a delay of several hours, the disappearance from the gland of previously trapped iodide. This transport is obviously directed from the follicle lumen to the interstitium, across the epithelium; provided that the transport is transcellular (and not paracellular) the efflux observed in intact follicles must occur across the basolateral plasma membrane of the epithelial cells. TSH-stimulated iodide efflux has also been recognized in dispersed thyrocytes and thyrocytes in culture (2,3,(8)(9)(10)(11)(12). In these studies, however, iodide efflux was stimulated within a few minutes of exposure to TSH. It appears, therefore, that the TSH-stimulated iodide efflux observed in isolated thyrocytes is funda¬ mentally different from the efflux observed in thyroid tissue with intact follicular arrangement.In recent years, increased attention has been paid to the intracellular...

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Section: Discussionmentioning

confidence: 94%

Polarized efflux of iodide in porcine thyrocytes occurs via a cAMP-regulated iodide channel in the apical plasma membrane

Nilsson

Björkman

Ekholm

et al. 1992

Acta Endocrinologica

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“…EGFinduced mitogenesis in the absence of detectable inositol phospholipid hydrolysis has been reported in Balb/c/3T3 fibroblasts (Besterman et al, 1986), and Chinese hamster embryo fibroblasts (IIC9 cells), (Wright et al, 1988). On the other hand, stimulation of Ptdlns hydrolysis by EGF has been reported in Balb/MK cells (Moscat et al, 1988), pig thyroid cells (Takasu et al, 1988) and rat hepatocytes (Tsao et al, 1986;Johnson and Garrison, 1987;Hepler et al, 1988). The reason for this difference among different cell types has not been fully explained, although differences in cell clones, experimental conditions, including the presence or absence of serum, and cell state may play some role (reviewed by Whitman and Cantley, 1989).…”

Section: Introductionmentioning

confidence: 98%

Differential induction of phosphatidylcholine hydrolysis, diacylglycerol formation and protein kinase C activation by epidermal growth factor and transforming growth factor-α in normal human skin fibroblasts and keratinocytes

Reynolds

Talwar

Baldassare

et al. 1993

Biochemical Journal

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We have investigated coupling between the epidermal growth factor (EGF) receptor and the phospholipase C (PLC)/protein kinase C (PKC) signal-transduction system in normal skin fibroblasts and keratinocytes, for which EGF and transforming growth factor alpha (TGF-alpha) are mitogenic. EGF and TGF-alpha induced a rapid increase in tyrosine phosphorylation of the EGF receptor, in both fibroblasts and keratinocytes, but failed to induce tyrosine phosphorylation of PLC-gamma 1 or detectable phosphoinositide hydrolysis, as measured by two sensitive assays. In fibroblasts, EGF induced phosphatidylcholine (PC) hydrolysis, resulting in increased diacylglycerol (DAG). In contrast, in keratinocytes, there was no detectable PC hydrolysis or elevation of DAG in response to EGF or TGF-alpha. EGF and TGF-alpha activated PKC in fibroblasts, as evidenced by increased phosphorylation of a specific cellular PKC substrate (myristoylated alanine-rich C-kinase substrate, 'MARCKS'). In keratinocytes, TGF-alpha and EGF induced only a modest increase in MARCKS protein phosphorylation. This apparent modest activation of PKC, in the absence of detectable DAG formation, may have been mediated by arachidonic acid, which was released from keratinocytes in response to TGF-alpha, and has been shown to stimulate PKC activity in vitro. These data demonstrate that (1) in dermal fibroblasts and keratinocytes, which express normal levels of EGF receptors, EGF receptor activation is not coupled to tyrosine phosphorylation of PLC-gamma 1 or PtdIns hydrolysis, suggesting that these events are not required for the mitogenic activity of EGF or TGF-alpha in these cells, (2) coupling of EGF receptor to PC hydrolysis is cell-type specific, and (3) in skin fibroblasts, DAG, formed through EGF-induced PC hydrolysis, is capable of activating PKC.

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“…Activation of these mitogenic receptors leads to stimulation of gene expression and growth that requires multiple phosphorylation steps involving protein tyrosine kinases. In addition, there are examples of ligand activation of receptor tyrosine kinases that elevate [Ca 2ϩ ] i (9,40). Participation of tyrosine kinases in signaling events gains complexity as it is recognized that other families of tyrosine kinases are located in the cytosol and are devoid of extracellular binding sites for ligands (16).…”

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confidence: 99%

Effect of tyrosine kinase blockade on norepinephrine-induced cytosolic calcium response in rat afferent arterioles

Salomonsson

Arendshorst

2004

American Journal of Physiology-Renal Physiology

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We used genistein (Gen) and tyrphostin 23 (Tyr-23) to evaluate the importance of tyrosine phosphorylation in norepinephrine (NE)-induced changes in intracellular free calcium concentration ([Ca(2+)](i)) in rat afferent arterioles. [Ca(2+)](i) was measured in microdissected arterioles using ratiometric photometry of fura 2 fluorescence. The control [Ca(2+)](i) response to NE (1 microM) consisted of a rapid initial peak followed by a plateau phase sustained above baseline. Pretreatment with the tyrosine kinase inhibitor Tyr-23 (50 microM, 10 min) caused a slow 40% increase in baseline [Ca(2+)](i). Tyr-23 attenuated peak and plateau responses to NE, both by approximately 70%. In the absence of extracellular Ca(2+) (0 Ca), Tyr-23 reduced the immediate [Ca(2+)](i) response to NE by approximately 60%, indicative of mobilization of internal stores, and abolished the plateau phase. In other arterioles, the [Ca(2+)](i) response to depolarization induced by KCl (50 mM) was not attenuated by Tyr-23, indicating no direct effect on L-type Ca(+) channels activated by depolarization. The Ca(2+) channel blocker nifedipine (1 microM) inhibited the NE response by approximately 50%; the effects of nifedipine and Tyr-23 were not additive. Nifedipine had no inhibitory effect after Tyr-23 pretreatment, indicating Tyr-23 inhibition of Ca(2+) entry. Another tyrosine kinase inhibitor, Gen (5 and 50 microM), did not affect baseline [Ca(2+)](i). High-dose Gen inhibited the peak and plateau response to NE by 87 and 75%, respectively; low-dose Gen attenuated both responses by approximately 20%. In 0 Ca, Gen (50 microM) abolished the immediate [Ca(2+)](i) mobilization response. Combined nifedipine and Gen (50 microM) inhibited the rapid NE response by approximately 90% in the presence of extracellular Ca(2+). Gen (50 microM) also inhibited by 60% the [Ca(2+)](i) response to 50 mM KCl, indicating a direct interaction with voltage-sensitive, L-type Ca(2+) entry channels. These results indicate that tyrosine phosphorylation is an important link in the chain of events leading to alpha-adrenoceptor-induced Ca(2+) recruitment (both entry and release) in afferent arteriolar smooth muscle cells. Furthermore, different blockers of tyrosine kinase appear to have different modes of action in renal microvessels.

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Epidermal growth factor (EGF) produces inositol phosphates and increases cytoplasmic free calcium in cultured porcine thyroid cells

Cited by 27 publications

References 19 publications

Polarized efflux of iodide in porcine thyrocytes occurs via a cAMP-regulated iodide channel in the apical plasma membrane

Polarized efflux of iodide in porcine thyrocytes occurs via a cAMP-regulated iodide channel in the apical plasma membrane

Differential induction of phosphatidylcholine hydrolysis, diacylglycerol formation and protein kinase C activation by epidermal growth factor and transforming growth factor-α in normal human skin fibroblasts and keratinocytes

Effect of tyrosine kinase blockade on norepinephrine-induced cytosolic calcium response in rat afferent arterioles

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