Protein kinase C acts downstream of calcium at entry into the first mitotic interphase of Xenopus laevis.

Capco, David G.

doi:10.1091/mbc.1.3.315

Cited by 68 publications

(35 citation statements)

References 57 publications

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“…In the sea urchin Lytechinus pictus, [Ca2+]i elevates within seconds, yet PKC translocation increases slowly (half-life of 23.3 min) and reaches maximal values 60-100 min after fertilization (Olds et al, 1995). Because phorbol ester inhibits [Ca21]i release (Swann et al, 1989;Bement and Capco, 1990;Grandin and Charbonneau, 1991) After Xenopus fertilization, both PKCa and 3activity increased at 7-10 min and decreased just before cleavage; DAG mass increased by 7-10 min and decreased during cleavage. However, DAG mass and PKC translocation are not always simultaneously elevated.…”

Section: Discussionmentioning

confidence: 99%

“…Not Prevent the Increase in DAG or Choline To examine the mechanism of the increase in DAG and choline, a BAPTA-calcium solution was injected into eggs to prevent any increase in [Ca2+1i (Kline, 1988;Bement and Capco, 1990;Grandin and Charbonneau, 1992;Stith et al, 1994 (Stith et al, 1994). In the presence of BAPTA, IP3 production at fertilization was actually enhanced (Stith et al, 1994).…”

Section: Prevention Of the Fertilization (Ca2+] Increase Didmentioning

confidence: 99%

“…There is evidence for second negative role; phorbol esters (which activate PKC) inhibit the fertilization [Ca2+]i increase (Bement and Capco, 1990) and the [Ca2+]i and intracellular pH increase induced by ionophore (Grandin and Charbonneau, 1991). PKC may terminate the fertilization [Ca2+]i increase in hamsters (Swann et al, 1989) but not sea urchin eggs (Ciapa et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Prevention Of the Fertilization (Ca2+] Increase Didmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Stith

Woronoff

Espinoza

et al. 1997

MBoC

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“…Although the current data do not exclude the possibility that csp displays additional functions at nerve terminals (where Ca 2ϩ sensing is important for the stimulus-evoked release of transmitter), our results indicate that csp participates in the regulated exocytotic cascade at a step that is independent of Ca 2ϩ . This conclusion is based on the fact that, as reviewed in the Introduction, PMA-triggered cortical granule exocytosis in Xenopus oocytes does not involve changes of cytosolic Ca 2ϩ and proceeds normally even when cytosolic Ca 2ϩ is buffered (5)(6)(7)31). However, cortical granule exocytosis is significantly disrupted by the overexpression of full-length csp, and the remainder of this investigation was aimed at clarifying the basis of this secretory blockade.…”

Section: Discussionmentioning

confidence: 99%

Interaction between Constitutively Expressed Heat Shock Protein, Hsc 70, and Cysteine String Protein Is Important for Cortical Granule Exocytosis in Xenopus Oocytes

Smith

Umbach

Hirano

et al. 2005

Journal of Biological Chemistry

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In many species, binding of sperm to the egg initiates cortical granule exocytosis, an event that contributes to a sustained block of polyspermy. Interestingly, cortical granule exocytosis can be elicited in immature Xenopus oocytes by the protein kinase C activator, phorbol-12-myristate-13-acetate. In this study, we investigated the role of cysteine string protein (csp) in phorbol-12-myristate-13-acetate-evoked cortical granule exocytosis. Prior work indicated that csp is associated with cortical granules of Xenopus oocytes. In oocytes exhibiting >20-fold overexpression of full-length Xenopus csp, cortical granule exocytosis was reduced by ϳ80%. However, csp overexpression did not affect constitutive exocytosis. Subcellular fractionation and confocal fluorescence microscopy revealed that little or none of the overexpressed csp was associated with cortical granules. This accumulation of csp at sites other than cortical granules suggested that mislocalized csp might sequester a protein that is important for regulated exocytosis. Because the NH 2 -terminal region of csp includes a J-domain, which interacts with constitutively expressed 70-kDa heat shock proteins (Hsc 70), we evaluated the effect of overexpressing the J-domain of csp. Although the native J-domain of csp inhibited cortical granule exocytosis, point mutations that interfere with J-domain binding to Hsc 70 eliminated this inhibition. These data indicate that csp interaction with Hsc 70 molecular chaperones is vital for regulated secretion in Xenopus oocytes.Eggs of many species exhibit cortical granule exocytosis, an early postfertilization event that leads to a sustained block of polyspermy (1). Although oocytes of Xenopus laevis must undergo maturation before sperm can elicit cortical granule exocytosis, immature oocytes (and eggs) of Xenopus secrete in response to activators of protein kinase C (2). Somewhat unexpectedly (given that the majority of regulated secretory events are initiated by an increase of cytosolic Ca 2ϩ , Refs. 3 and 4), cortical granule exocytosis in Xenopus oocytes is insensitive to changes of cytosolic Ca 2ϩ . For instance, this secretory event is not triggered by Ca 2ϩ ionophores (using physiological concentrations of Ca 2ϩ ); it cannot be evoked by direct injection of Ca 2ϩ into the cytoplasm, and it is unaffected by removal of extracellular Ca 2ϩ or by buffers that clamp cytosolic Ca 2ϩ below the resting level (5-7). Thus, oocytes offer an empirical avenue for assessing the function of proteins in a secretory pathway where calcium ions play no direct role. This issue is of considerable importance with respect to cysteine string proteins (csp 2 (s)), a class of proteins found associated with a broad range of regulated secretory organelles (8 -10).Csp was originally identified as a novel synaptic antigen in Drosophila (11), and several subsequent investigations indicated that csp might be important as a modulator of presynaptic Ca 2ϩ channels (12-17). However, it also became evident that regulation of presynaptic Ca 2ϩ channe...

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“…Some of these treatments result in only .partial activation, e.g. protein kinase C stimulators in Xenopus cause cortical granule release, but no intracellular calcium or pH changes (Bement and Capco, 1990). Some aspects of ooycte activation have been characterized in in vitro matured domestic pig oocytes (Didion et al, 1990;Funahas'hi and Day, 1993;Machaty et al, 19951, but there are few reports of artificial activation of in viuo matured oocytes from domestic (Prather et al, 1989) or miniature pigs.…”

Section: Introductionmentioning

confidence: 99%

Artificial Activation of Oocytes from Sinclair Miniature Pigs

Prather

Gibson

Parry

1996

Journal of Applied Animal Research

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Protein kinase C acts downstream of calcium at entry into the first mitotic interphase of Xenopus laevis.

Abstract: Transit into interphase of the first mitotic cell cycle in amphibian eggs is a process referred to as activation and is accompanied by an increase in in-

Cited by 68 publications

References 57 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.

Interaction between Constitutively Expressed Heat Shock Protein, Hsc 70, and Cysteine String Protein Is Important for Cortical Granule Exocytosis in Xenopus Oocytes

Artificial Activation of Oocytes from Sinclair Miniature Pigs

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