Characterization of protein kinase C in Xenopus oocytes

Sahara, Setsuko; Sato, Kenichi; Aoto, Mamoru; Ohnishi, Tetsuo; Kaise, Hiroshi; Koide, Hiroshi; Ogita, Kouji; Fukami, Yasuo

doi:10.1016/s0006-291x(05)80118-4

Cited by 26 publications

(11 citation statements)

References 17 publications

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“…Phosphorylation studies suggest that PKC inhibits cleavage furrow formation (Satterwhite et al, 1992) and a phorbol ester has been found to inhibit cleavage in mouse oocytes (Niemierko and Komar, 1985). Because phorbol esters rapidly down-regulate at least one PKC isozyme in Xenopus (Sahara et al, 1992), phorbol ester may induce cleavage furrow formation in Xenopus [for review, Bement and Capco (1989, 1990, 1991a Significance of the DAG Changes The timing of the PKC activation is crucial because events such as cortical granule breakdown and cleavage may be due to PKC (see review by Bement, 1992). In Xenopus, the initial increases in DAG and PKC activation are after the peaks of [Ca2+]i (Busa et al, 1985b) or IP3 (Stith et al, 1993(Stith et al, , 1994.…”

Section: Discussionmentioning

confidence: 99%

sn-1,2-diacylglycerol and choline increase after fertilization in Xenopus laevis.

Stith

Woronoff

Espinoza

et al. 1997

MBoC

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sn-1,2-Diacylglycerol (DAG) mass and translocation of protein kinase C a and ,B to a membrane fraction increased -7 min after insemination of Xenopus laevis eggs. The DAG mass increase of 48 pmol (from 62 to 110 pmol/cell) was greater than that for inositol 1,4,5-trisphosphate (1P3; an increase of -170 fmol or -280-fold smaller than the DAG increase), and DAG peaks -5 min after IP3. Choline mass (a measure of phosphatidylcholine-specific phospholipase D) also peaked before DAG and the choline increase (134 pmol/cell) was greater than that of DAG. There was no detectable change in phosphocholine mass (a measure of phosphatidylcholine-specific phospholipase C). During first cleavage, DAG decreased, PKC translocation was low, and choline increased and peaked (whereas published work shows an increase in IP3 mass). Artificial elevation of intracellular calcium ([Ca2+]

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Section: Discussionmentioning

confidence: 99%

sn-1,2-diacylglycerol and choline increase after fertilization in Xenopus laevis.

Stith

Woronoff

Espinoza

et al. 1997

MBoC

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“…These data considered together suggest that PKC activation may facilitate nAChR desensitization, though, in mouse embryonic preparations, this modulation takes place only under particular cell conditions, which might either increase cell sensitivity to TPA or favour actions of PKC on nAChR. Xenopus oocytes, which are endowed with endogenous TPA-sensitive PKC activities (Sahara et al, 1992), represent a particularly suitable preparation to examine the effects of pharmacologically stimulated PKC on nAChR.…”

Section: Discussionmentioning

confidence: 99%

“…It is known that Xenopus oocytes express endogenous TPA-sensitive PKC activities (Sahara et al, 1992). We were interested in examining whether short-term phorbol ester treatments, comparable to those used in electrophysiological experiments, were able to activate PKC(s in oocytes co-injected with rat brain mRNA and C2C12-mRNA; 5HT stimulates the PtdIns turnover, and consequently activates PKC, in oocytes injected with rat brain mRNA (Gundersen et al, 1983;Parker et al, 1985;Nomura et al, 1987;Parker et al, 1990).…”

Section: Tpa Down-regulates Pkcmentioning

confidence: 99%

“…This preparation was chosen because the properties of nAChRs observed in the native cells are well conserved when receptors are 'transplanted' into oocytes (Miledi et al, 1982;Kullberg et al, 1990;Lo et al, 1990;Witzemann et al, 1990). In addition, Xenopus oocytes express at least two distinct endogenous TPA-sensitive PKC activities (Sahara et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

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Protein kinase C modulates exogenous acetylcholine current in Xenopus oocytes

Mileo¹,

Palma²,

Polenzani³

et al. 1995

J of Neuroscience Research

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The modulation of acetylcholine-activated current (IACh) by protein kinase C (PKC) was studied in Xenopus laevis oocytes microinjected with either mRNA extracted from C2C12 myotubes (C2C12 mRNA) or RNAs encoding murine alpha beta gamma delta subunits of the nicotinic ACh receptor (nAChR). Voltage-clamped oocytes were treated for 90 sec with 12-O-tetradecanoylphorbol-13-acetate (TPA, 300 nM), a potent PKC activator. Transient increase in the amplitude and acceleration in the decay of IACh were invariably observed within minutes of TPA application, and were independent of extracellular Ca2+ concentration. Both parameters recovered to control within 20-30 min; then a slight depression of IACh developed. By this time, an initial PKC down regulation was observed. At the peak of TPA-induced potentiation, dose-response relations suggested an increased binding affinity of nAChR for the neurotransmitter. 4 alpha-phorbol 12,13-didecanoate (300 nM), a biologically inactive analogue of TPA, did not affect IACh, while staurosporine (5-10 microM), a potent inhibitor of PKC activity, suppressed the action of TPA on IACh. In oocytes co-injected with C2C12 mRNA and with rat brain mRNA, IACh was potentiated by 5-hydroxy-tryptamine (10 microM), whose receptors are coupled to phosphoinositide hydrolysis. The nAChR-channel activity in cell-attached patches increased when TPA was applied to the oocytes. In 50% of the oocytes examined, a sustained depression of the single channel activity followed. We conclude that in Xenopus oocytes an endogenous PKC system regulates the function of embryonic-type muscle nAChRs.

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“…In agreement with this conclusion are data recently re ported by Logvinenko et al [20] 7) and expressed rat a subunits (fig. 8) can be phosphorylated by PKCs of different origin: by PMA-stimulated PKC from Xeno pus oocytes, which is a mixture of two iso forms, PKC 1 and PKC II [21], and by PKC from the rat brain, which is a mixture of a, (3, y isoforms (information provided by the sup plier). Compared to phosphorylation by rat brain PKC, a somewhat more pronounced 32P labeling of the endogenous pump is observed if endogenous Xenopus PKC is activated by PMA ( fig.…”

mentioning

confidence: 99%

Diversity of Regulatory Phosphorylation of the Na+/K+-ATPase from Mammalian Kidneys and XenopusOocytes by Protein Kinases: Characterization of the Phosphorylation Site for Protein Kinase C

Vasilets¹

1997

Cell Physiol Biochem

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Protein-kinase-mediated phosphorylation of the Na⁺/K⁺-ATPase has been studied in enzymes purified from pig, dog, sheep, and rat kidneys and in Xenopus oocytes. None of the α subunits from mammalian kidney ATPase is phosphorylated by casein kinase II and Ca²⁺/calmodulin-dependent protein kinase. For the purified enzymes, rat protein kinase C (PKC) phosphorylates only the α subunit of the Na⁺/K⁺-ATPase from rat kidney. Rat α1 subunits mutated in the putative phosphorylation sites Ser-23 and Ser-16 by Ala were co-expressed in Xenopus oocytes with β subunits, and modulation of transport activity as well as phosphorylation of endogenous Xenopus and of expressed rat pumps by PKC was investigated. Activation of endogenous PKC from the Xenopus oocytes by phorbol ester produces inhibition of ouabain-sensitive ⁸⁶Rb uptake of Xenopus pumps by 40 ± 6%. Microinjection into the oocytes of exogenous rat PKC or its catalytic domain PKM leads to an increase in ⁸⁶Rb uptake by 41 ± 5 and 25 ± 2%, respectively. On the other hand, in rat α1 isoform expressed in Xenopus oocytes, the rat PKC inhibits ouabain-sensitive ⁸⁶Rb uptake by 79 ± 4%. Both endogenous Xenopus α subunits and expressed wild-type rat α1 sub-units are phosphorylated by rat PKC. In contrast to its effect on the expressed rat wild-type pump, rat PKC does not inhibit transport activity and does not phosphorylate the α subunit of the S23A mutant. If Ser-16 instead of Ser-23 is substituted by Ala, the mutated α subunits are still phosphorylated, but transport activity of mutated pumps is not modulated by PKC. The data demonstrate that Ser-23 is the actual site of regulatory phosphorylation of rat PKC in the rat kidney α1 subunit, but Ser-16 is, nevertheless, important to mediate the effects of PKC-induced phosphorylation to the changes in transport activity. Substitution of both Ser-23 and Ser-16 by Ala does not influence the inhibition of transport activity and does not abolish phosphorylation of mutated pumps if endogenous Xenopus PKC is activated by PMA. This suggests that additional sites in the rat α1 subunit may be phosphorylated during PMA-dependent activation of the Xenopus PKC.

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Characterization of protein kinase C in Xenopus oocytes

Cited by 26 publications

References 17 publications

sn-1,2-diacylglycerol and choline increase after fertilization in Xenopus laevis.

sn-1,2-diacylglycerol and choline increase after fertilization in Xenopus laevis.

Protein kinase C modulates exogenous acetylcholine current in Xenopus oocytes

Diversity of Regulatory Phosphorylation of the Na<sup>+</sup>/K<sup>+</sup>-ATPase from Mammalian Kidneys and <i>Xenopus</i>Oocytes by Protein Kinases: Characterization of the Phosphorylation Site for Protein Kinase C

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