共查询到20条相似文献,搜索用时 8 毫秒
1.
NAADP participates in the response of starfish oocytes to sperm by triggering the fertilization potential (FP) through the activation of a Ca2+ current which depolarizes the membrane to the threshold of activation of the voltage-gated Ca2+ channels. The aim of this study was to investigate whether this Ca2+ influx is linked to the onset of the concomitant InsP3-mediated Ca2+ wave by simultaneously employing Ca2+ imaging and single-electrode intracellular recording techniques. In control oocytes, the sperm-induced membrane depolarization always preceded by a few seconds the onset of the Ca2+ wave. Strikingly, the self-desensitization of NAADP receptors either abolished the Ca2+ response or resulted in abnormal oocyte activation, i.e., the membrane depolarization followed the Ca2+ wave and the oocyte was polyspermic. The inhibition of InsP3 signaling only impaired the propagation of the Ca2+ wave and shortened the FP. The duration of FP was also reduced in low-Na+ sea water. Finally, uncaged InsP3 produced a Ca2+ increase, which depolarized the membrane upon the activation of a Ca2+-sensitive cation current. These results support the hypothesis that Ca2+ entry during the NAADP-triggered FP is required for the onset of the Ca2+ wave at fertilization. The InsP3-mediated Ca2+ wave, in turn, may interact with the NAADP-evoked depolarization by activating a Ca2+-dependent Na+ entry. 相似文献
2.
Actin cytoskeleton modulates calcium signaling during maturation of starfish oocytes 总被引:2,自引:0,他引:2
Kyozuka K Chun JT Puppo A Gragnaniello G Garante E Santella L 《Developmental biology》2008,320(2):426-435
Before successful fertilization can occur, oocytes must undergo meiotic maturation. In starfish, this can be achieved in vitro by applying 1-methyladenine (1-MA). The immediate response to 1-MA is the fast Ca2+ release in the cell cortex. Here, we show that this Ca2+ wave always initiates in the vegetal hemisphere and propagates through the cortex, which is the space immediately under the plasma membrane. We have observed that alteration of the cortical actin cytoskeleton by latrunculin-A and jasplakinolide can potently affect the Ca2+ waves triggered by 1-MA. This indicates that the cortical actin cytoskeleton modulates Ca2+ release during meiotic maturation. The Ca2+ wave was inhibited by the classical antagonists of the InsP3-linked Ca2+ signaling pathway, U73122 and heparin. To our surprise, however, these two inhibitors induced remarkable actin hyper-polymerization in the cell cortex, suggesting that their inhibitory effect on Ca2+ release may be attributed to the perturbation of the cortical actin cytoskeleton. In post-meiotic eggs, U73122 and jasplakinolide blocked the elevation of the vitelline layer by uncaged InsP3, despite the massive release of Ca2+, implying that exocytosis of the cortical granules requires not only a Ca2+ rise, but also regulation of the cortical actin cytoskeleton. Our results suggest that the cortical actin cytoskeleton of starfish oocytes plays critical roles both in generating Ca2+ signals and in regulating cortical granule exocytosis. 相似文献
3.
Gilda A Nusco Dmitri Lim Pawel Sabala Luigia Santella 《Biochemical and biophysical research communications》2002,290(3):1015-1021
During the reinitiation of the meiotic cycle (maturation) induced by the hormone 1-methyladenine (1-MA), starfish oocytes undergo structural and biochemical changes in preparation for successful fertilization. Previous work has shown that the sensitivity of internal Ca(2+) stores to InsP(3) increases during maturation of the oocytes. Since Astropecten auranciacus oocytes also respond to cADPr, we have studied whether the response to cADPr also changes during maturation. We have found that the photoactivation of injected cADPr in immature oocytes immediately induces multiple patches of Ca(2+) release in the cortical region. The Ca(2+) signal then spreads from these initial points of increase to the entire cell. In mature oocytes, the uncaging of cADPr induces instead a single (or at most a dual) initial point of Ca(2+) release, which is immediately followed by the formation of a cortical Ca(2+) flash and then by the globalization of the wave and by the elevation of the fertilization envelope. External Ca(2+) plays a role in the Ca(2+) responses. Inhibition of L-type Ca(2+) channels does not affect the initial Ca(2+) release, but abolishes the cortical flash and impairs the elevation of the fertilization envelope. External Ca(2+) has other effects, as shown by the irregular appearance of the surface of oocytes incubated in Ca(2+)-free sea water. The sequence of Ca(2+) responses induced by cADPr in mature oocytes mimics those seen at fertilization, i.e., a first localized Ca(2+) increase followed by a cortical flash and by the globalization of the Ca(2+) signal. As in the case of maturation, L-type Ca(2+) channel blockers abolish the sperm induced cortical flash. 相似文献
4.
Dyer JL Mobasheri H Lea EJ Dawson AP Michelangeli F 《Biochemical and biophysical research communications》2003,302(1):121-126
The effects of protein kinase A (PKA) on the inositol 1,4,5-trisphosphate (InsP(3)) receptor isoforms type I and type III were studied. The effects of PKA on the extent and rate constants for InsP(3)-induced Ca(2+) release (IICR) were different for the two isoforms. The effects of PKA on the type I isoform showed a biphasic relationship dependent upon the concentration of PKA used. At low concentrations of PKA (<50U/ml), both the extent and rate constants for IICR increased, while at higher concentrations (>200U/ml) the extent and rate constants decreased. The type III isoform showed only an increase in the extent of IICR and not in the rate constants. The effects of PKA on the type I InsP(3) receptor using single channel electrophysiological studies were also investigated. The stimulatory effect of PKA is due to an increase in conductance levels and not to a change in the mean open time of the channel. 相似文献
5.
Vertebrate oocytes proceed through meiosis I before undergoing a cytostatic factor (CSF)-mediated arrest at metaphase of meiosis II. Exit from MII arrest is stimulated by a sperm-induced increase in intracellular Ca2+. This increase in Ca2+ results in the destruction of cyclin B1, the regulatory subunit of cdk1 that leads to inactivation of maturation promoting factor (MPF) and egg activation. Progression through meiosis I also involves cyclin B1 destruction, but it is not known whether Ca2+ can activate the destruction machinery during MI. We have investigated Ca2+ -induced cyclin destruction in MI and MII by using a cyclin B1-GFP fusion protein and measurement of intracellular Ca2+. We find no evidence for a role for Ca2+ in MI since oocytes progress through MI in the absence of detectable Ca2+ transients. Furthermore, Ca2+ increases induced by photorelease of InsP3 stimulate a persistent destruction of cyclin B1-GFP in MII but not MI stage oocytes. In addition to a steady decrease in cyclin B1-GFP fluorescence, the increase in Ca2+ stimulated a transient decrease in fluorescence in both MI and MII stage oocytes. Similar transient decreases in fluorescence imposed on a more persistent fluorescence decrease were detected in cyclin-GFP-injected eggs undergoing fertilization-induced Ca2+ oscillations. The transient decreases in fluorescence were not a result of cyclin B1 destruction since transients persisted in the presence of a proteasome inhibitor and were detected in controls injected with eGFP and in untreated oocytes. We conclude that increases in cytosolic Ca2+ induce transient changes in autofluorescence and that the pattern of cyclin B1 degradation at fertilization is not stepwise but exponential. Furthermore, this Ca2+ -induced increase in degradation of cyclin B1 requires factors specific to mature oocytes, and that to overcome arrest at MII, Ca2+ acts to release the CSF-mediated brake on cyclin B1 destruction. 相似文献
6.
Agonist-induced oscillations in the concentration of intracellular free calcium ([Ca2+]1) display a wide variety of temporal and spatial patterns. In non-excitable cells, typical oscillatory patterns are somewhat cell-type specific and range from frequency-encoded, repetitive Ca2+ spikes to oscillations that are more sinusoidal in shape. Although the response of a cell population, even to the same stimulus, is often extremely heterogeneous, the response of the same cell to successive exposures can be remarkably similar. We propose that such ‘Ca 2+ fingerprints’ can be a consequence of cell-specific morphological properties. The hypothesis is tested by means of a stochastic computer simulation of a two-dimensional model for oscillatory Ca 2+ waves which encompasses the basic elements of the two-pool oscillator introduced by Goldbeter et al. (Goldbeter A., Dupont G., Berridge M.J. Minimal model for signal-induced Ca2+-oscillations and for their frequency encoding through protein phosphorylation. Proc Natl Acad Sci USA 1990; 87: 1461–1465). In the framework of our extended spatiotemporal model, single cells can display various oscillation patterns which depend on the agonist dose, Ca2+ diffusibility, and several morphological parameters. These are, for example, size and shape of the cell and the cell nucleus, the amount and distribution of Ca2+ stores, and the subcellular location of the inositol(1,4,5)-trisphosphate-generating apparatus. 相似文献
7.
Sugita Kenji Mörk Ann-Christin Zhang Guo H. Martinez J. Ricardo 《Molecular and cellular biochemistry》1999,198(1-2):39-46
The expression of protein kinase C (PKC) isoforms and the modulation of Ca2+ mobilization by PKC were investigated in the human submandibular duct cell line A253. Three new PKC (nPKC) isoforms (, , and ) and one atypical PKC (aPKC) isoform () are expressed in this cell line. No classical PKC (cPKC) isoforms were present. The effects of the PKC activator phorbol 12-myristate-13-acetate (PMA) and of the PKC inhibitors calphostin C (CC) and bisindolymaleimide I (BSM) on inositol 1,4,5-trisphosphate (IP3) and Ca2+ responses to ATP and to thapsigargin (TG) were investigated. Pre-exposure to PMA inhibited IP3 formation, Ca2+ release and Ca2+ influx in response to ATP. Pre-exposure to CC or BSM slightly enhanced IP3 formation but inhibited the Ca2+ release and the Ca2+ influx induced by ATP. In contrast, pre-exposure to PMA did not modify the Ca2+ release induced by TG, but reduced the influx of Ca2+ seen in the presence of this Ca2+-ATPase inhibitor. These results suggest that PKC modulates elements of the IP3/Ca2+ signal transduction pathway in A253 cells by (1) inhibiting phosphatidylinositol turnover and altering the sensitivity of the Ca2+ channels to IP3, (2) altering the activity, the sensitivity to inhibitors, or the distribution of the TG-sensitive Ca2+ ATPase, and (3) modulating Ca2+ entry pathways. 相似文献
8.
We demonstrate that the application of the muscarinic agonist carbachol to the human salivary epithelial cell line HSG elicits the now well-known phenomenon of quantal Ca2+-release; namely, that the application of a submaximal concentration of agonist results in the release of only a portion of the agonist-sensitive intracellular Ca2+ pool. One explanation that has been proposed to account for this effect is that there are multiple intracellular Ca2+ stores, each with a different agonist sensitivity, which release Ca2+ in an all-or-none fashion. We test this hypothesis in intact HSG cells with an experimental protocol designed to preferentially load less-agonist-sensitive stores with 45Ca2+ and more-agonist-sensitive stores with 45Ca2+. However, contrary to the expectations of the above explanation, these cells do not preferentially release 45Ca2+ in response to low concentrations of agonist. Thus our data suggest that quantal Ca2+ release must arise from some other property of the stores or their Ca2+ release channels. 相似文献
9.
Tabata H Tanaka S Sugimoto Y Kanki H Kaneko S Ichikawa A 《Biochemical and biophysical research communications》2002,298(3):398-402
We previously reported that the prostaglandin E(2) (PGE(2)) receptor subtype EP(1) is coupled to intracellular Ca(2+) mobilization in CHO cells, which is dependent on extracellular Ca(2+) in a pertussis toxin-insensitive manner [H. Katoh, et al., Biochim. Biophys. Acta 1244 (1995) 41-48]. However, it remains unknown about the signal transduction involved in this response. To investigate the mechanism regulating Ca(2+) mobilization mediated by EP(1) receptors in detail, we performed a series of experiments using the Xenopus laevis oocyte expression system and found that endogenous G(q) and/or G(11), and not G(i1) is involved in the Ca(2+) mobilization induced by PGE(2). We further investigated the receptor-activated Ca(2+) channel (RACC)-related response by introducing mRNA for mouse transient receptor potential 5 (TRP5), a possible candidate for the RACC, and found effective coupling between them. These results suggest that the EP(1) receptors induce Ca(2+) mobilization via G(q) and/or G(11) and Ca(2+) influx via TRP. 相似文献
10.
Calcium and inositol trisphosphate receptors 总被引:4,自引:0,他引:4
Work from the authors' laboratory is supported by the Wellcome Trust, and the Medical, and Agricultural and Food Research Councils. CWT is a Lister Institute Research Fellow. 相似文献
11.
Storchak L. Tarasenko A. Linetska M. Pozdnyakova N. Himmelreich N. 《Neurophysiology》2002,34(5):321-325
The main inhibitory neurotransmitter GABA in the mammalian brain is distributed in the nerve terminals between two pools, vesicular (synaptic vesicles) and cytosolic. GABA is released from these pools by different mechanisms; there are calcium-activated exocytotic release and calcium-independent sodium-dependent release from the cytosolic pool (resulting from the membrane GABA transporter reversal). We investigated the influence of temperature on [3H]GABA release from rat brain synaptosomes, which was induced by stimulation of both these processes. In addition, we used -latrotoxin as a stimulant of [3H]GABA release. Synaptosomes from the rat brain were used in the experiments. 4-Aminopyridine (4-AP) and high [KCl] were applied to stimulate calcium-activated and calcium-independent [3H]GABA release, respectively. 4-AP-evoked [3H]GABA release was of the same intensity at 37 and 25°C (10.1 ± 1.2 and 10.1 ± 0.8% of total [3H]GABA incorporated into the synaptosomes, respectively). The effect of 4-AP on the 45Ca2+ influx into synaptosomes was also temperature-independent: 0.775 ± 0.075 and 0.725 ± 0.100 nmol/min/mg of protein at 37 and 25°C, respectively. A drop in the effect of 4-AP was observed only at 15°C. When synaptosomes were depolarized with 50 mM KCl, a temperature decrease from 37°C to 25°C resulted in a twofold drop in the [3H]GABA release, from 20.5 ± 1.4 to 10.3 ± 0.7%; at 15°C [3H]GABA release dropped to less than one-third of the norm (6.0 ± 0.5%). -Latrotoxin-stimulated [3H]GABA release was diminished from 32.5 ± 2.5 at 37°C to 17.2 ± 1.3 at 25°C and 5.9 ± 0.4% at 15°C and was not affected by the presence or absence of calcium in the medium. It seems likely that the observed effect of temperature can be interpreted as based on the temperature dependence of the -latrotoxin insertion into the membrane. It is suggested that the pattern of the temperature sensitivity of GABA release from the synaptosomes can be used as a criterion for identification of the mode of neurotransmitter release. 相似文献
12.
ATP-independent luminal oscillations and release of Ca2+ and H+ from mast cell secretory granules: implications for signal transduction
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InsP(3) is an important link in the intracellular information network. Previous observations show that activation of InsP(3)-receptor channels on the granular membrane can turn secretory granules into Ca(2+) oscillators that deliver periodic trains of Ca(2+) release to the cytosol (T. Nguyen, W. C. Chin, and P. Verdugo, 1998, Nature, 395:908-912; I. Quesada, W. C. Chin, J. Steed, P. Campos-Bedolla, and P. Verdugo, 2001, BIOPHYS: J. 80:2133-2139). Here we show that InsP(3) can also turn mast cell granules into proton oscillators. InsP(3)-induced intralumenal [H(+)] oscillations are ATP-independent, result from H(+)/K(+) exchange in the heparin matrix, and produce perigranular pH oscillations with the same frequency. These perigranular pH oscillations are in-phase with intralumenal [H(+)] but out-of-phase with the corresponding perigranular [Ca(2+)] oscillations. The low pH of the secretory compartment has critical implications in a broad range of intracellular processes. However, the association of proton release with InsP(3)-induced Ca(2+) signals, their similar periodic nature, and the sensitivity of important exocytic proteins to the joint action of Ca(2+) and pH strongly suggests that granules might encode a combined Ca(2+)/H(+) intracellular signal. A H(+)/Ca(2+) signal could significantly increase the specificity of the information sent by the granule by transmitting two frequency encoded messages targeted exclusively to proteins like calmodulin, annexins, or syncollin that are crucial for exocytosis and require specific combinations of [Ca(2+)] "and" pH for their action. 相似文献
13.
14.
Phaeocystis globosa, a leading agent in marine carbon cycling, releases its photosynthesized biopolymers via regulated exocytosis. Release is elicited by blue light and relayed by a characteristic cytosolic Ca(2+) signal. However, the source of Ca(2+) in these cells has not been established. The present studies indicate that Phaeocystis' secretory granules work as an intracellular Ca(2+) oscillator. Optical tomography reveals that photo-stimulation induces InsP(3)-triggered periodic lumenal [Ca(2+)] oscillations in the granule and corresponding out-of-phase cytosolic oscillations of [Ca(2+)] that trigger exocytosis. This Ca(2+) dynamics results from an interplay between the intragranular polyanionic matrix, and two Ca(2+)-sensitive ion channels located on the granule membrane: an InsP(3)-receptor-Ca(2+) channel, and an apamin-sensitive K(+) channel. 相似文献
15.
Sehwon Koh Kiho Lee Chunmin Wang Ryan A. Cabot Zoltan Machaty 《Developmental biology》2009,330(2):368-376
The single transmembrane-spanning Ca2+-binding protein, STIM1, has been proposed to function as a Ca2+ sensor that links the endoplasmic reticulum to the activation of store-operated Ca2+ channels. In this study, the presence, subcellular localization and function of STIM1 in store-operated Ca2+ entry in oocytes was investigated using the pig as a model. Cloning and sequence analysis revealed the presence of porcine STIM1 with a coding sequence of 2058 bp. In oocytes with full cytoplasmic Ca2+ stores, STIM1 was localized predominantly in the inner cytoplasm as indicated by immunocytochemistry or overexpression of human STIM1 conjugated to the yellow fluorescent protein. Depletion of the Ca2+ stores was associated with redistribution of STIM1 along the plasma membrane. Increasing STIM1 expression resulted in enhanced Ca2+ influx after store depletion and subsequent Ca2+ add-back; the influx was inhibited when the oocytes were pretreated with lanthanum, a specific inhibitor of store-operated Ca2+ channels. When STIM1 expression was suppressed using siRNAs, there was no change in cytosolic free Ca2+ levels in the store-depleted oocytes after Ca2+ add-back. The findings suggest that in oocytes, STIM1 serves as a sensor of Ca2+ store content that after store depletion moves to the plasma membrane to stimulate store-operated Ca2+ entry. 相似文献
16.
Diptiman D. Bose 《Biochemical and biophysical research communications》2009,379(2):594-133
Regulation of bi-directional communication between intracellular Ca2+ pools and surface Ca2+ channels remains incompletely characterized. We report Ca2+ release mediated by inositol 1,4,5-trisphosphate receptor (IP3R) and ryanodine receptor (RyR) pathways is diminished under actin cytoskeleton disruption in NG115-401L (401L) neuronal cells, yet despite truncated Ca2+ release, Ca2+ influx was not significantly altered in these experiments. However, disruption of cortical actin networks completely abolished IP3R induced Ca2+ release, whereas RyR-mediated Ca2+ release was preserved, albeit attenuated. Moreover, cortical actin disruption completely abolished IP3R and RyR linked Ca2+ influx even though Ca2+ pool sensitivities were different. These findings suggest discrete Ca2+ store/Ca2+ channel coupling mechanisms in the IP3R and RyR pathways as revealed by the differential sensitivity to actin perturbation. 相似文献
17.
Lu yao Zhang Meng Lin Zhuan Qingrui Wang Zichuan Li Junjin Liu Kexiong Fu Xiangwei Hou Yunpeng 《Cell proliferation》2021,54(11)
ObjectivesThe alteration of bioenergetics by oocytes in response to the demands of various biological processes plays a critical role in maintaining normal cellular physiology. However, little is known about the association between energy sensing and energy production with energy‐dependent cellular processes like meiosis.Materials and methodsWe demonstrated that cell cycle‐dependent mitochondrial Ca2+ connects energy sensing to mitochondrial activity in meiosis progression within mouse oocytes. Further, we established a model in mouse oocytes using siRNA knockdowns that target mitochondrial calcium uniporters (MCUs) in order to inhibit mitochondrial Ca2+ concentrations.ResultsDecreased numbers of oocytes successfully progressed to the germinal vesicle stage and extruded the first polar body during in vitro culture after inhibition, while spindle checkpoint‐dependent meiosis was also delayed. Mitochondrial Ca2+ levels changed, and this was followed by altered mitochondrial masses and ATP levels within oocytes during the entirety of meiosis progression. Abnormal mitochondrial Ca2+ concentrations in oocytes then hindered meiotic progress and activated AMP‐activated protein kinase (AMPK) signalling that is associated with gene expression.ConclusionsThese data provide new insight into the protective role that MCU‐dependent mitochondrial Ca2+ signalling plays in meiotic progress, in addition to demonstrating a new mechanism of mitochondrial energy regulation by AMPK signalling that influences meiotic maturation. 相似文献
18.
Using fura-2-acetoxymethyl ester (AM) fluorescence imaging and patch clamp techniques, we found that endothelin-1 (ET-1) significantly
elevated the intracellular calcium level ([Ca2+]i) in a dose-dependent manner and activated the L-type Ca2+ channel in cardiomyocytes isolated from rats. The effect of ET-1 on [Ca2+]i elevation was abolished in the presence of the ETA receptor blocker BQ123, but was not affected by the ETB receptor blocker BQ788. ET-1-induced an increase in [Ca2+]i, which was inhibited 46.7% by pretreatment with a high concentration of ryanodine (10 μmol/L), a blocker of the ryanodine
receptor. The ET-1-induced [Ca2+]i increase was also inhibited by the inhibitors of protein kinase A (PKA), protein kinase C (PKC) and angiotensin type 1 receptor
(AT1 receptor). We found that ET-1 induced an enhancement of the amplitude of the whole cell L-type Ca2+ channel current and an increase of open-state probability (NPo) of an L-type single Ca2+ channel. BQ123 completely blocked the ET-1-induced increase in calcium channel open-state probability. In this study we demonstrated
that ET-1 regulates calcium overload through a series of mechanisms that include L-type Ca2+ channel activation and Ca2+-induced Ca2+ release (CICR). ETA receptors, PKC, PKA and AT1 receptors may also contribute to this pathway.
Supported by the National Natural Science Foundation of China (Grant No. 200830870910). 相似文献
19.
Machaca K 《Developmental biology》2004,275(1):170-182
The universal signal for egg activation at fertilization is a rise in cytoplasmic Ca(2+) with defined spatial and temporal kinetics. Mammalian and amphibian eggs acquire the ability to produce such Ca(2+) signals during a maturation period that precedes fertilization and encompasses resumption of meiosis and progression to metaphase II. In Xenopus, immature oocytes produce fast, saltatory Ca(2+) waves that can be oscillatory in nature in response to IP(3). In contrast, mature eggs produce a single continuous, sweeping Ca(2+) wave in response to IP(3) or sperm fusion. The mechanisms mediating the differentiation of Ca(2+) signaling during oocyte maturation are not well understood. Here, I characterized elementary Ca(2+) release events (Ca(2+) puffs) in oocytes and eggs and show that the sensitivity of IP(3)-dependent Ca(2+) release is greatly enhanced during oocyte maturation. Furthermore, Ca(2+) puffs in eggs have a larger spatial fingerprint, yet are short lived compared to oocyte puffs. Most interestingly, Ca(2+) puffs cluster during oocyte maturation resulting in a continuum of Ca(2+) release sites over space in eggs. These changes in the spatial distribution of elementary Ca(2+) release events during oocyte maturation explain the continuous nature and slower speed of the fertilization Ca(2+) wave. 相似文献
20.
Respiring rat liver mitochondria are known to spontaneously release the Ca2+ taken up when they have accumulated Ca2+ over a certain threshold, while Sr2+ and Mn2+ are well tolerated and retained. We have studied the interaction of Sr2+ with Ca2+ release. When Sr2+ was added to respiring mitochondria simultaneously with or soon after the addition of Ca2+, the release was potently inhibited or reversed. On the other hand, when Sr2+ was added before Ca2+, the release was stimulated. Ca2+-induced mitochondrial damage and release of accumulated Ca2+ is generally believed to be due to activation of mitochondrial phospholipase A (EC 3.1.1.4.) by Ca2+. However, isolated mitochondrial phospholipase A activity was little if at all inhibited by Sr2+. The Ca2+ -release may thus be triggered by some Ca2+ -dependent function other than phospholipase. 相似文献