Stimulation of porcine thyroid cell alkalinization and growth by EGF, phorbol ester, and diacylglycerol

1990 ◽  
Vol 258 (3) ◽  
pp. E445-E450
Author(s):  
N. Takasu ◽  
I. Komiya ◽  
Y. Nagasawa ◽  
T. Asawa ◽  
T. Shinoda ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Growth ◽  
Phorbol Ester ◽  
Thyroid Cell ◽  
Ph Indicator ◽  
Thyroid Cells ◽  
Kinase C ◽  
Epidermal Growth ◽  
Stimulation Of

We studied the effects of epidermal growth factor (EGF), 12-O-tetradecanoylphorbol-13-acetate (TPA), and 1-oleoyl-2-acetyl-glycerol (OAG) on cytoplasmic pH (pHi) and cell growth in cultured porcine thyroid cells. pHi was measured using 2',7'-bis(2-carboxyethyl-5,6-carboxyfluorescein (BCECF), an internalized fluorescent pH indicator. EGF, TPA, and OAG alkalinized the thyroid cells and stimulated their growth. These EGF-, TPA-, and OAG-stimulated cell alkalinization and growth depended on extracellular Na concentrations and were inhibited by amiloride, an inhibitor of Na(+)-H+ exchanger, indicating that EGF-, TPA-, and OAG-stimulated cell alkalinization and growth may occur through activation of Na(+)-H+ exchange. Alkalinization seems to be involved in thyroid cell growth. TPA (a tumor-promoting phorbol ester) and OAG (synthetic diacylglycerol), both potent activators of protein kinase C, imitate the action of EGF in rapidly elevating pHi and stimulating cell growth in thyroid cells. Trifluoperazine, an inhibitor of protein kinase C, inhibited EGF-, TPA-, and OAG-stimulated cell alkalinization and growth. The data suggest that activation of protein kinase C may be involved in the mechanism of EGF-stimulated cell alkalinization and growth of the thyroid cells.

scholarly journals Bombesin and epidermal growth factor stimulate the mitogen-activated protein kinase through different pathways in Swiss 3T3 cells

1993 ◽  
Vol 289 (1) ◽  
pp. 283-287 ◽  
Author(s):  
L Pang ◽  
S J Decker ◽  
A R Saltiel
Keyword(s):  
Enzyme Activity ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Map Kinase ◽  
3T3 Cells ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Epidermal Growth ◽  
Swiss 3T3 ◽  
Stimulation Of

Both bombesin and epidermal growth factor (EGF) are potent mitogens in Swiss 3T3 cells that nonetheless have dissimilar receptor structures. To explore possible common intracellular events involved in the stimulation of cellular growth by these two peptides, we have evaluated the regulation of the mitogen-activated protein (MAP) kinase. Exposure of Swiss 3T3 cells to bombesin, EGF or the protein kinase C activator phorbol 12-myristate 13-acetate (PMA) causes the rapid and transient stimulation of the enzyme activity. Pretreatment of cells with the protein kinase inhibitor H-7, or down-regulation of cellular protein kinase C by prolonged exposure to PMA, causes a decrease of over 90% in the activation of MAP kinase by bombesin. In contrast, these treatments have no effect on the stimulation of MAP kinase by EGF. The stimulation of MAP kinase activity by bombesin is dose-dependent, occurring over a narrow concentration range of the peptide. Both EGF and bombesin stimulate the phosphorylation of an immunoprecipitable MAP kinase protein migrating at 42 kDa on SDS/PAGE. Phosphoamino acid analysis of this phosphorylated protein reveals that EGF and bombesin stimulate phosphorylation on tyrosine, threonine and serine residues. Tyrosine phosphorylation of the enzyme, as evaluated by antiphosphotyrosine blotting of the immunoprecipitated protein, reveals that the time course of phosphorylation by both mitogens correlates with stimulation of enzyme activity. These results provide further evidence for the convergence of discrete pathways emanating from tyrosine kinase and G-protein-linked receptors in the regulation of MAP kinase.

Effects of protein kinase C activators on the in-vitro action of thyrotrophin in pigs

1988 ◽  
Vol 118 (2) ◽  
pp. 199-203 ◽  
Author(s):  
J. Ginsberg ◽  
P. G. Murray
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Thyroid Function ◽  
Receptor Site ◽  
Thyroid Cell ◽  
Thyroid Cells ◽  
Cell Extracts ◽  
Kinase C

ABSTRACT The ability of the non-phorbol protein kinase C (PKC) activator 12-hydroxy-daphnetoxin (mezerein) to modulate differentiated thyroid function was examined in vitro. A dose-dependent inhibition of TSH-stimulated iodide organification was observed in porcine thyroid cells exposed to mezerein. Under identical conditions mezerein caused the translocation of PKC from its inactive cytosolic form to an active membrane-bound form in thyroid cell extracts. The relative biological potencies of mezerein and the phorbol ester, 12-0-tetradecanoylphorbol-13-acetate (TPA), to inhibit thyroid function in vitro corresponded to their abilities to activate PKC. This effect was also observed when dibutyryl cyclic AMP was used, implying a post-receptor site of action. To provide further evidence for this concept, the effects of mezerein and TPA on receptor-related events were studied. Neither mezerein nor TPA had any effect on the binding of radiolabelled TSH to solubilized porcine thyroid membranes. However, both mezerein and TPA were capable of stimulating cyclic AMP (cAMP) production in porcine thyroid cells in the basal state but could not augment TSH or forskolin-activated cAMP release. These data provide evidence that activation of PKC plays a role in the regulation of differentiated thyroid function in vitro and suggest that the effects of PKC are complex, with independent actions on cAMP accumulation and post-receptor events. J. Endocr. (1988) 118, 199–203

scholarly journals Osmotic and phorbol ester-induced activation of Na+/H+ exchange: possible role of protein phosphorylation in lymphocyte volume regulation.

1985 ◽  
Vol 101 (1) ◽  
pp. 269-276 ◽  
Author(s):  
S Grinstein ◽  
S Cohen ◽  
J D Goetz ◽  
A Rothstein
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Time Course ◽  
Phorbol Esters ◽  
Underlying Mechanism ◽  
Atp Depletion ◽  
Sequence Of Events ◽  
Kinase C ◽  
Stimulation Of

The Na+/H+ antiport is stimulated by 12-O-tetradecanoylphorbol-13, acetate (TPA) and other phorbol esters in rat thymic lymphocytes. Mediation by protein kinase C is suggested by three findings: (a) 1-oleoyl-2-acetylglycerol also activated the antiport; (b) trifluoperazine, an inhibitor of protein kinase C, blocked the stimulation of Na+/H+ exchange; and (c) activation of countertransport was accompanied by increased phosphorylation of specific membrane proteins. The Na+/H+ antiport is also activated by osmotic cell shrinking. The time course, extent, and reversibility of the osmotically induced and phorbol ester-induced responses are similar. Moreover, the responses are not additive and they are equally susceptible to inhibition by trifluoperazine, N-ethylmaleimide, and ATP depletion. The extensive analogies between the TPA and osmotically induced effects suggested a common underlying mechanism, possibly activation of a protein kinase. It is conceivable that osmotic shrinkage initiates the following sequence of events: stimulation of protein kinase(s) followed by activation of the Na+/H+ antiport, resulting in cytoplasmic alkalinization. The Na+ taken up through the antiport, together with the HCO3- and Cl- accumulated in the cells as a result of the cytoplasmic alkalinization, would be followed by osmotically obliged water. This series of events could underlie the phenomenon of regulatory volume increase.

scholarly journals Epidermal growth factor stimulation of stromelysin mRNA in rat fibroblasts requires induction of proto-oncogenes c-fos and c-jun and activation of protein kinase C.

1990 ◽  
Vol 10 (8) ◽  
pp. 4284-4293 ◽  
Author(s):  
S E McDonnell ◽  
L D Kerr ◽  
L M Matrisian
Keyword(s):  
Protein Kinase C ◽  
Growth Factor ◽  
Protein Kinase ◽  
Epidermal Growth Factor ◽  
Kinase Activation ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Epidermal Growth ◽  
Rat Fibroblasts ◽  
Stimulation Of

Stromelysin (transin) is a secreted metalloprotease that is transcriptionally induced by a variety of growth factors and oncogenes. We examined the necessity of specific secondary (protein kinase C) and tertiary (c-fos and c-jun protein products) messengers in the transactivation of stromelysin gene expression by epidermal growth factor (EGF). Rat-1 fibroblasts exposed to antisense c-fos DNA or RNA demonstrated that c-fos expression was necessary for complete EGF induction of stromelysin expression. Similar results demonstrating the necessity of c-jun protein in the EGF induction of stromelysin were obtained. We also demonstrated that protein kinase C activation is required for the EGF induction of stromelysin, since phorbol ester desensitization of C kinase proteins abolished the ability of EGF to induce stromelysin mRNA, protein, and promoter activity. In reconstitution experiments, neither c-fos, c-jun, nor C kinase activation alone induced significant stromelysin expression. Overexpression of c-fos and c-jun was able to induce stromelysin to a level similar to that of the growth factor, and stimulation of protein kinase C activity augmented this induction. The data suggest that the EGF induction of stromelysin in rat fibroblasts procedes through a pathway involving c-fos, c-jun, and protein kinase C.

Thyroid-stimulating hormone activates phospholipase D in FRTL-5 thyroid cells via stimulation of protein kinase C.

Endocrinology ◽  
1995 ◽  
Vol 136 (9) ◽  
pp. 3794-3799 ◽  
Author(s):  
S Gupta ◽  
A Gomez-Muñoz ◽  
W C Matowe ◽  
D N Brindley ◽  
J Ginsberg
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase D ◽  
Thyroid Stimulating Hormone ◽  
Thyroid Cells ◽  
Kinase C ◽  
Stimulation Of ◽  
Stimulating Hormone

scholarly journals Rapid stimulation of amyloid precursor protein release by epidermal growth factor: role of protein kinase C

1997 ◽  
Vol 327 (1) ◽  
pp. 245-249 ◽  
Author(s):  
Barbara E. SLACK ◽  
Jeffrey BREU ◽  
Lisa MUCHNICKI ◽  
Richard J. WURTMAN
Keyword(s):  
Protein Kinase C ◽  
Growth Factor ◽  
Protein Kinase ◽  
Epidermal Growth Factor ◽  
Amyloid Precursor Protein ◽  
Egf Receptor ◽  
A431 Cells ◽  
Kinase C ◽  
Epidermal Growth ◽  
Stimulation Of

The amyloid precursor protein (APP) of Alzheimer's disease is a transmembrane protein that is cleaved by an uncharacterized enzyme known as α-secretase within its extracellular/intraluminal domain after the activation of guanine nucleotide-binding protein-coupled receptors linked to phosphoinositide hydrolysis. The secretory process results in the release of large soluble derivatives of APP (APPs), and, when elicited by muscarinic receptor activation, exhibits both protein kinase C (PKC)-dependent and tyrosine phosphorylation-dependent components [Slack, Breu, Petryniak, Srivastava and Wurtman (1995) J. Biol. Chem. 270, 8337–8344]. In this report we examine the regulation of the release of APPs by epidermal growth factor (EGF) receptors, which possess intrinsic tyrosine kinase activity, and are coupled to a variety of effectors including phosphoinositide-specific phospholipase Cγ. In A431 cells, EGF caused time-dependent and dose-dependent increases in the formation of inositol phosphates in cultures prelabelled with myo-[3H]inositol, and in the release of APPs into the culture medium; the two responses exhibited similar time courses and EC50 values for EGF. Concomitant with these effects, there were concentration-dependent (3–300 ng/ml) increases in the phosphorylation of tyrosine residues in several proteins, including the EGF receptor itself. The specific PKC antagonist GF 109203X decreased the effect of EGF by approx. 35% at a concentration that abolished the stimulation of the release of APPs by the PKC activator PMA. Tyrphostin AG 1478, an inhibitor of EGF receptor tyrosine kinase, abolished the EGF-induced release of APPs. These results demonstrate that in A431 cells, activation of the EGF receptor stimulates α-secretase activity by a mechanism that is partly dependent on PKC activity.

Phorbol esters inhibit ammoniagenesis and gluconeogenesis in proximal tubular segments

1987 ◽  
Vol 252 (6) ◽  
pp. F1073-F1079
Author(s):  
M. C. Chobanian ◽  
M. R. Hammerman
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Proximal Tubule ◽  
Phorbol Ester ◽  
Phorbol Esters ◽  
Extracellular Ph ◽  
Linear Functions ◽  
Kinase C ◽  
Proximal Tubular ◽  
Stimulation Of

To characterize the regulation of ammoniagenesis and gluconeogenesis in renal proximal tubule, ammonia and glucose productions were measured in suspensions of canine proximal tubular segments incubated with 10 mM L-glutamine. Productions were linear functions of time for 120 min and were decreased as extracellular pH was increased from 7.0 to 7.5 To ascertain whether activation of protein kinase c affects either process, we incubated segments with tumor-promoting phorbol esters, 12-O-tetradecanoylphorbol-13-acetate (TPA), or phorbol 12,13-dibutyrate, or with the inactive phorbol ester 4 alpha-phorbol. Ammoniagenesis and gluconeogenesis were inhibited by incubation with 10(-6) M of the two former compounds but not the latter compound. Inhibition of ammoniagenesis and gluconeogenesis occurred after incubation with as little as 10(-9) M phorbol 12,13-dibutyrate. Phorbol ester-induced inhibition was observed under conditions such that extracellular [Na+] was greater than intracellular [Na+], but not when extracellular [Na+] equaled intracellular [Na+], and was not observed in the presence of amiloride. Our findings are consistent with a role for protein kinase c in the control of ammoniagenesis and gluconeogenesis in proximal tubule. Such control could be mediated via stimulation of Na+-H+ exchange.

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