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1.
Bcl-2 interaction with the inositol 1,4,5-trisphosphate receptor: role in Ca(2+) signaling and disease 总被引:1,自引:0,他引:1
The Bcl-2 protein, best known for its ability to inhibit apoptosis, interacts with the inositol 1,4,5-trisphosphate receptor (IP3R) Ca2+ channel to regulate IP3-mediated Ca2+ release from the endoplasmic reticulum. This review summarizes the current state of knowledge regarding the interaction of Bcl-2, and also its homologue Bcl-xl, with the IP3R and how these interactions regulate Ca2+ signaling. The dual role of these interactions in promoting prosurvival Ca2+ signals, while at the same time inhibiting proapoptotic Ca2+ signals, is discussed. Moreover, this review will elucidate the recently recognized importance of the Bcl-2-IP3R interaction in human disease. 相似文献
2.
The inositol 1,4,5-trisphosphate (InsP3) receptor was purified from bovine cerebellum and reconstituted in liposomes composed of phosphatidylcholine (PC) and phosphatidylethanolamine
(PE) (1:1) successfully. No effect of Ca2+ concentration on [3H]-InsP3 binding to unreconstituted InsP3 receptor could be observed either at 4°C or at 25°C, whereas the effect of [Ca2+] on reconstituted InsP3 receptor depended on the temperature. The Ca2+ concentration outside the proteolipsome ([Ca2+]o) had no detectable effect on InsP3 binding to InsP3 receptor at 4°C. In contrast, with increase of [Ca2+]o from 0 to 100 nmol/L at 25°C, the InsP3 binding activity increased gradually. Then the InsP3 binding activity was decreased drastically at higher [Ca2+]o and inhibited entirely at 50 μmol/L [Ca2+]o. Conformational studies on intrinsic fluorescence of the reconstituted InsP3 receptor and its quenching by KI and HB indicated that the global conformation of reconstituted InsP3 receptor could not be affected by [Ca2+]o at 4°C. While at 25°C, the effects of 10 μmol/L [Ca2+]o on global, membrane and cytoplasmic conformation of the reconstituted InsP3 receptor were different significantly from that of 100 nmol/L [Ca2+]o. 相似文献
3.
The properties of inositol 1,4,5-trisphosphate (IP3)-dependent intracellular calcium oscillations in pancreatic acinar cells depend crucially on the agonist used to stimulate them. Acetylcholine or carbachol (CCh) cause high-frequency (10-12-s period) calcium oscillations that are superimposed on a raised baseline, while cholecystokinin (CCK) causes long-period (>100-s period) baseline spiking. We show that physiological concentrations of CCK induce rapid phosphorylation of the IP3 receptor, which is not true of physiological concentrations of CCh. Based on this and other experimental data, we construct a mathematical model of agonist-specific intracellular calcium oscillations in pancreatic acinar cells. Model simulations agree with previous experimental work on the rates of activation and inactivation of the IP3 receptor by calcium (DuFour, J.-F., I.M. Arias, and T.J. Turner. 1997. J. Biol. Chem. 272:2675-2681), and reproduce both short-period, raised baseline oscillations, and long-period baseline spiking. The steady state open probability curve of the model IP3 receptor is an increasing function of calcium concentration, as found for type-III IP3 receptors by Hagar et al. (Hagar, R.E., A.D. Burgstahler, M.H. Nathanson, and B.E. Ehrlich. 1998. Nature. 396:81-84). We use the model to predict the effect of the removal of external calcium, and this prediction is confirmed experimentally. We also predict that, for type-III IP3 receptors, the steady state open probability curve will shift to lower calcium concentrations as the background IP3 concentration increases. We conclude that the differences between CCh- and CCK-induced calcium oscillations in pancreatic acinar cells can be explained by two principal mechanisms: (a) CCK causes more phosphorylation of the IP3 receptor than does CCh, and the phosphorylated receptor cannot pass calcium current; and (b) the rate of calcium ATPase pumping and the rate of calcium influx from the outside the cell are greater in the presence of CCh than in the presence of CCK. 相似文献
4.
A model explaining quantal Ca2+ release as an intrinsic property of the inositol 1,4,5-trisphosphate (IP3) receptor has been put forward. The model is based on the hypothesis that the IP3 receptor can catalyze a transformation of the IP, molecule differing from its conventional metabolism. A simple kinetic mechanism is considered, in which IP3-induced Ca2+ channel opening is followed by the step of IP3 conversion and channel closure. Examination of the resulting mathematical model shows that it can reproduce well both partial release of stored Ca2+ and the same responsiveness to subsequent IP3 additions. On incorporation of an additional closed state of the channel, the model describes also a time-dependent channel inactivation at a high IP3 dose. Temperature sensitivity of the catalytic step accounts for the reported elimination of quantal responses and inactivation at low temperature. The transformation product is surmised to be a positional or stereo isomer of IP3. 相似文献
5.
Abou-Lovergne A Collado-Hilly M Monnet FP Koukoui O Prigent S Coquil JF Dupont G Combettes L 《Cell calcium》2011,50(1):62-72
In hepatocytes, as in other cell types, Ca2+ signaling is subject to complex regulations, which result largely from the intrinsic characteristics of the different inositol 1,4,5-trisphosphate receptor (InsP3R) isoforms and from their interactions with other proteins. Although sigma1 receptors (Sig-1Rs) are widely expressed in the liver, their involvement in hepatic Ca2+ signaling remains unknown. We here report that in this cell type Sig-1R interact with type 1 isoforms of the InsP3 receptors (InsP3R-1). These results obtained by immunoprecipitation experiments are confirmed by the observation that Sig-1R proteins and InsP3R-1 colocalize in hepatocytes. However, Sig-1R ligands have no effect on InsP3-induced Ca2+ release in hepatocytes. This can be explained by the rather low expression level expression of InsP3R-1. In contrast, we find that Sig-1R ligands can inhibit agonist-induced Ca2+ signaling via an inhibitory effect on InsP3 synthesis. We show that this inhibition is due to the stimulation of PKC activity by Sig-1R, resulting in the well-known down-regulation of the signaling pathway responsible for the transduction of the extracellular stimulus into InsP3 synthesis. The PKC sensitive to Sig-1R activity belongs to the family of conventional PKC, but the precise molecular mechanism of this regulation remains to be elucidated. 相似文献
6.
Ichiroh Fujino Norihiko Yamada Atsushi Miyawaki Mamoru Hasegawa Teiichi Furuichi Katsuhiko Mikoshiba 《Cell and tissue research》1995,280(2):201-210
The inositol 1,4,5-trisphosphate receptor (IP3R) is an intracellular Ca2+ release channel responsible for mobilizing stored Ca2+. Three different receptor types have been molecularly cloned, and their genes have been classified into a family. The gene for the type 1 receptor (IP3R1) is predominantly expressed in cerebellar Purkinje neurons, but its gene product is localized widely in a variety of tissues; however, there is little information on what types of cells express the other two receptor types, type 2 and type 3 (IP3R2 and IP3R3, respectively). We studied the expression of the IP3R gene family in various mouse tissues by in situ hybridization histochemistry. Compared with IP3R1, the levels of expression of IP3R2 and IP3R3 mRNAs were low in all of the tissues tested. IP3R2 mRNA was localized in the intralobular duct cells of the submandibular gland, the urinary tubule cells of the kidney, the epithelial cells of epididymal ducts and the follicular granulosa cells of the ovary, while the IP3R3 mRNA was distributed in gastric cells, salivary and pancreatic acinar cells and the epithelium of the small intestine. All of these cells which express either IP3R2 or IP3R3 mRNA are known to have a secretory function in which IP3/Ca2+ signalling has been shown to be involved, and thus either IP3R2 or IP3R3 may be a prerequisite to secretion in these cells. 相似文献
7.
Yoo SH 《Cell calcium》2011,50(2):175-183
The majority of secretory cell calcium is stored in secretory granules that serve as the major IP3-dependent intracellular Ca2+ store. Even in unicellular phytoplankton secretory granules are responsible for the IP3-induced Ca2+ release that triggers exocytosis. The number of secretory granules in the cell is directly related not only to the magnitude of IP3-induced Ca2+ release, which accounts for the majority of the IP3-induced cytoplasmic Ca2+ release in neuroendocrine cells, but also to the IP3 sensitivity of the cytoplasmic IP3 receptor (IP3R)/Ca2+ channels. Moreover, secretory granules contain the highest IP3R concentrations and the largest amounts of IP3Rs in any subcellular organelles in neuroendocrine cells. Secretory granules from phytoplankton to mammals contain large amounts of polyanionic molecules, chromogranins being the major molecules in mammals, in addition to acidic intragranular pH and high Ca2+ concentrations. The polyanionic molecules undergo pH- and Ca2+-dependent conformational changes that serve as a molecular basis for condensation-decondensation phase transitions of the intragranular matrix. Likewise, chromogranins undergo pH- and Ca2+-dependent conformational changes with increased exposure of the structure and increased interactions with Ca2+ and other granule components at acidic pH. The unique physico-chemical properties of polyanionic molecules appear to be at the center of biogenesis, and physiological functions of secretory granules in living organisms from primitive to advanced species. 相似文献
8.
It has been established that inositol 1,4,5-trisphosphate(IP3) is responsible for the mobilization of calcium(Ca2+) from intracellular locations in a wide variety of tissues, and that this response triggers the stimulation of several hormones and neurotransmitters. However, these phenomena have yet to be examined in the mammary epithelium. Ca2+ uptake from the medium into the endoplasmic reticulum(ER) and Golgi apparatus in vitro in both pregnant and lactating mouse mammary epithelial cells was studied and a strong Ca2+ release from these organelles into the medium with the use of IP3 was shown. The Ca2+ uptake and its release due to IP3 was also usually greater during pregnancy than lactation. 相似文献
9.
Chaloux B Caron AZ Guillemette G 《Biology of the cell / under the auspices of the European Cell Biology Organization》2007,99(7):379-388
Background information. In endocrine cells, IP3R (inositol 1,4,5‐trisphosphate receptor), a ligand‐gated Ca2+ channel, plays an important role in the control of intracellular Ca2+ concentration. There are three subtypes of IP3R that are distributed differentially among cell types. RINm5F cells express almost exclusively the IP3R‐3 subtype. The purpose of the present study was to investigate the effect of PKA (protein kinase A) on the activity of IP3R‐3 in RINm5F cells. Results. We show that immunoprecipitated IP3R‐3 is a good substrate for PKA. Using a back‐phosphorylation approach, we show that endogenous PKA phosphorylates IP3R‐3 in intact RINm5F cells. [3H]IP3 (inositol 1,4,5‐trisphosphate) binding affinity and IP3‐induced Ca2+ release activity were enhanced in permeabilized cells that were pre‐treated with forskolin or PKA. The PKA‐induced enhancement of IP3R‐3 activity was also observed in intact RINm5F cells stimulated with carbachol and epidermal growth factor, two agonists that use different receptor types to activate phospholipase C. Conclusion. The results of the present study reveal a converging step where the cAMP and the Ca2+ signalling systems act co‐operatively in endocrine cell responses to external stimuli. 相似文献
10.
Chan J Whitten AE Jeffries CM Bosanac I Mal TK Ito J Porumb H Michikawa T Mikoshiba K Trewhella J Ikura M 《Journal of molecular biology》2007,373(5):1269-1280
Cytoplasmic Ca2+ signals are highly regulated by various ion transporters, including the inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R), which functions as a Ca2+ release channel on the endoplasmic reticulum membrane. Crystal structures of the two N-terminal regulatory regions from type 1 IP(3)R have been reported; those of the IP(3)-binding core (IP(3)R(CORE)) with bound IP(3), and the suppressor domain. This study examines the structural effects of ligand binding on an IP(3)R construct, designated IP(3)R(N), that contains both the IP(3)-binding core and the suppressor domain. Our circular dichroism results reveal that the IP(3)-bound and IP(3)-free states have similar secondary structure content, consistent with preservation of the overall fold within the individual domains. Thermal denaturation data show that, while IP(3) has a large effect on the stability of IP(3)R(CORE), it has little effect on IP(3)R(N), indicating that the suppressor domain is critical to the stability of IP(3)R(N). The NMR data for IP(3)R(N) provide evidence for chemical exchange, which may be due to protein conformational dynamics in both apo and IP(3)-bound states: a conclusion supported by the small-angle X-ray scattering data. Further, the scattering data show that IP(3)R(N) undergoes a change in average conformation in response to IP(3) binding and the presence of Ca2+ in the solution. Taken together, these data lead us to propose that there are two flexible linkers in the N-terminal region of IP(3)R that join stably folded domains and give rise to an equilibrium mixture of conformational sub-states containing compact and more extended structures. IP(3) binding drives the conformational equilibrium toward more compact structures, while the presence of Ca2+ drives it to a more extended set. 相似文献
11.
Hristina Ivanova Tim Vervliet Ludwig Missiaen Jan B. ParysHumbert De Smedt Geert Bultynck 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2014
Cell-death and -survival decisions are critically controlled by intracellular Ca2 + homeostasis and dynamics at the level of the endoplasmic reticulum (ER). Inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) play a pivotal role in these processes by mediating Ca2 + flux from the ER into the cytosol and mitochondria. Hence, it is clear that many pro-survival and pro-death signaling pathways and proteins affect Ca2 + signaling by directly targeting IP3R channels, which can happen in an IP3R-isoform-dependent manner. In this review, we will focus on how the different IP3R isoforms (IP3R1, IP3R2 and IP3R3) control cell death and survival. First, we will present an overview of the isoform-specific regulation of IP3Rs by cellular factors like IP3, Ca2 +, Ca2 +-binding proteins, adenosine triphosphate (ATP), thiol modification, phosphorylation and interacting proteins, and of IP3R-isoform specific expression patterns. Second, we will discuss the role of the ER as a Ca2 + store in cell death and survival and how IP3Rs and pro-survival/pro-death proteins can modulate the basal ER Ca2 + leak. Third, we will review the regulation of the Ca2 +-flux properties of the IP3R isoforms by the ER-resident and by the cytoplasmic proteins involved in cell death and survival as well as by redox regulation. Hence, we aim to highlight the specific roles of the various IP3R isoforms in cell-death and -survival signaling. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau. 相似文献
12.
Akihiro Nezu Akihiko TanimuraTakao Morita Akiko ShitaraYosuke Tojyo 《Biochimica et Biophysica Acta (BBA)/General Subjects》2006
LIBRA is a fluorescent biosensor of inositol 1,4,5-trisphosphate (IP3) and is composed of the ligand-binding domain of the rat type 3 IP3 receptor and cyan and yellow fluorescent proteins. We examined the responses of LIBRA and its IP3-insensitive mutant LIBRA-N to compounds known to inhibit IP3-induced Ca2+ release. Heparin, a competitive antagonist of IP3 receptors, increased the emission ratio of LIBRA but not that of LIBRA-N. In contrast, 2-aminoethoxydiphenyl borate, a known non-competitive inhibitor of IP3 receptor, decreased the emission ratios of both LIBRA and LIBRA-N. Thus, the concurrent use of LIBRA-N with LIBRA identifies nonspecific responses. These results indicate that LIBRA and its mutant control can be used to detect specific agonists and antagonists of IP3 receptors. We also demonstrate the utility of LIBRA and LIBRA-N in discriminating between specific and nonspecific responses in intact cells. 相似文献
13.
14.
Zhou H Iwasaki H Nakamura T Nakamura K Maruyama T Hamano S Ozaki S Mizutani A Mikoshiba K 《Biochemical and biophysical research communications》2007,352(2):277-282
Capacitative calcium entry (CCE), the mechanism that replenishes the internal Ca2+ stores with Ca2+ from the extracellular milieu in response to depletion of the store, is mediated by Ca2+ channels in the plasma membrane generally referred to as store-operated channels (SOCs). However, the roles of SOCs in the more physiological context have been fully elucidated. 2-Aminoethyl diphenylborinate (2-APB) strongly inhibits SOCs, as well as inositol-1,4,5 trisphosphate (IP3) receptors. In the present study, we screened a library of 166 2-APB analogues for effects on CCE and IP3-induced Ca2+ release in order to discover specific SOC inhibitors, and found that some blocked both store-operated and receptor-operated Ca2+ influx more strongly and selectively than 2-APB. Indeed, these new compounds ceased the prolonged intracellular Ca2+ oscillations induced by a low concentration of ATP in CHO-K1 cells. These novel SOC inhibitors will be valuable pharmacological and biochemical tools for elucidating the physiological roles. 相似文献
15.
Calcium-dependent facilitation and graded deactivation of store-operated calcium entry in fetal skeletal muscle 总被引:2,自引:0,他引:2
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Activation of store-operated Ca2+ entry (SOCE) into the cytoplasm requires retrograde signaling from the intracellular Ca2+ release machinery, a process that involves an intimate interaction between protein components on the intracellular and cell surface membranes. The cellular machinery that governs the Ca2+ movement in muscle cells is developmentally regulated, reflecting maturation of the junctional membrane structure as well as coordinated expression of related Ca2+ signaling molecules. Here we demonstrate the existence of SOCE in freshly isolated skeletal muscle cells obtained from embryonic days 15 and 16 of the mouse embryo, a critical stage of muscle development. SOCE in the fetal muscle deactivates incrementally with the uptake of Ca2+ into the sarcoplasmic reticulum (SR). A novel Ca2+-dependent facilitation of SOCE is observed in cells transiently exposed to high cytosolic Ca2+. Our data suggest that cytosolic Ca2+ can facilitate SOCE whereas SR luminal Ca2+ can deactivate SOCE in the fetal skeletal muscle. This cooperative mechanism of SOCE regulation by Ca2+ ions not only enables tight control of SOCE by the SR membrane, but also provides an efficient mechanism of extracellular Ca2+ entry in response to physiological demand. Such Ca2+ signaling mechanism would likely contribute to contraction and development of the fetal skeletal muscle. 相似文献
16.
Proto-oncogenes and tumor suppressors critically control cell-fate decisions like cell survival, adaptation and death. These processes are regulated by Ca2 + signals arising from the endoplasmic reticulum, which at distinct sites is in close proximity to the mitochondria. These organelles are linked by different mechanisms, including Ca2 +-transport mechanisms involving the inositol 1,4,5-trisphosphate receptor (IP3R) and the voltage-dependent anion channel (VDAC). The amount of Ca2 + transfer from the endoplasmic reticulum to mitochondria determines the susceptibility of cells to apoptotic stimuli. Suppressing the transfer of Ca2 + from the endoplasmic reticulum to the mitochondria increases the apoptotic resistance of cells and may decrease the cellular responsiveness to apoptotic signaling in response to cellular damage or alterations. This can result in the survival, growth and proliferation of cells with oncogenic features. Clearly, proper maintenance of endoplasmic reticulum Ca2 + homeostasis and dynamics including its links with the mitochondrial network is essential to detect and eliminate altered cells with oncogenic features through the apoptotic pathway. Proto-oncogenes and tumor suppressors exploit the central role of Ca2 + signaling by targeting the IP3R. There are an increasing number of reports showing that activation of proto-oncogenes or inactivation of tumor suppressors directly affects IP3R function and endoplasmic reticulum Ca2 + homeostasis, thereby decreasing mitochondrial Ca2 + uptake and mitochondrial outer membrane permeabilization. In this review, we provide an overview of the current knowledge on the proto-oncogenes and tumor suppressors identified as IP3R-regulatory proteins and how they affect endoplasmic reticulum Ca2 + homeostasis and dynamics. 相似文献
17.
Catalina Carrasco-Pozo Edgar Pastene Carola Vergara Moises Zapata Cristian Sandoval Martin Gotteland 《Biochimica et Biophysica Acta (BBA)/General Subjects》2012
Background
The effect of indomethacin (INDO) on Ca2 + mobilization, cytotoxicity, apoptosis and caspase activation and the potential protective effect of quercetin (QUE), resveratrol (RES) and rutin (RUT) were determined in Caco-2 cells.Methods
Caco-2 cells were incubated with INDO in the presence or absence of QUE, RES or RUT. The concentrations of Ca2 + in the cytosol (Fluo-3 AM) and mitochondria (Rhod-2 AM) were determined as well as the cytotoxicity (MTT reduction and LDH leakage), apoptosis (TUNEL) and caspase-3 and 9 activities.Results
INDO promoted Ca2 + efflux from the endoplasmic reticulum (ER), resulting in an early, but transient, increment of cytosolic Ca2 + at 3.5 min, followed by a subsequent increment of intra-mitochondrial Ca2 + at 24 min. INDO also induced cytotoxicity, apoptosis, and increased caspase activities and cytochrome c release. All these alterations were prevented by the inhibitors of the IP3R and RyR receptors, 2-Aminoethoxydiphenyl borate (2-APB) and dantrolene. QUE was the most efficient polyphenol in preventing Ca2 + mobilization induced by INDO and all of its consequences including cytotoxicity and apoptosis.Conclusions
In Caco-2 cells, INDO stimulates ER Ca2 + mobilization, probably through the activation of IP3R and RyR receptors, and the subsequent entry of Ca2 + into the mitochondria. Polyphenols protected the cells against the Ca2 + mobilization induced by INDO and its consequences on cytotoxicity and apoptosis.General significance
These results confirm the possibility of using polyphenols and particularly QUE for the protection of the gastroduodenal mucosa in subjects consuming NSAIDs. 相似文献18.
Staurosporine (Stp) is an inhibitor of protein kinase C (PKC) that has been used to address the role of this enzyme in a variety of cells. However, Stp can also inhibit protein tyrosine kinases (PTK). We have investigated the effects of Stp on the InsP3- (using mAb C305 directed against the β chain of the T cell receptor (TcR)/CD3 complex) and the thapsigargin (Tg)-dependent release and influx of Ca2+ in human (Jurkat) T cells. The addition of Stp (200 nM) during the sustained phase of the TcR-dependent Ca2+ response resulted in a rapid inhibition of the influx of Ca2+ that was not seen when Ca2+ mobilization was triggered by Tg (1 μM). When the cells were preincubated with Stp (200 nM), there was an inhibition of the mAb C305- but not the Tg-dependent Ca2+ response. The effect of Stp was not the result of the inhibition of PKC as shown by down-regulation of PKC and with the use of the specific PKC inhibitor bis-indolyl maleimide GF 109203X. The effect of Stp on the entry of Ca2+ in activated (mAb C305) Jurkat lymphocytes was dose-related and was not the result of a direct inhibition of plasma membrane Ca2+ channels based on an absence of effect on the Tg-dependent entry of Ca2+ and the use of Ca2+ channel blockers (econazole and Ni2+). These blockers terminated the influx of Ca2+ but the Tg-sensitive Ca2+ reserves were not refilled in marked contrast to the effect of Stp. Quantification of InsP3 revealed that the addition of Stp resulted in an approximate 40% reduction in mAb C305-activated Jurkat cells. The effects of Stp can be explained as follows. Stp decreases the mAb C305-induced production of InsP3 by inhibiting the TcR/CD3-dependent activation of PTK associated with the stimulation of phospholipase C-γ1. A decrease in [InsP3] without a return to baseline is sufficient to close the InsP3 Ca2+ channel, endoplasmic Ca2+ ATPases use the incoming Ca2+ to refill the Ca2+ pools and that terminates the capacitative entry of Ca2+. A simple kinetic model reproduced the experimental data. 相似文献
19.
Current knowledge suggests that cell movement in the eukaryotic slime mold Dictyostelium discoideum is mediated by different signaling pathways involving a number of redundant components. Our previous research has identified a specific motility-enhancing function for epidermal growth factor-like (EGFL) repeats in Dictyostelium, specifically for the EGFL repeats of cyrA, a matricellular, calmodulin (CaM)-binding protein in Dictyostelium. Using mutants of cAMP signaling (carA−, carC−, gpaB−, gpbA−), the endogenous calcium (Ca2+) release inhibitor TMB-8, the CaM antagonist W-7, and a radial motility bioassay, we show that DdEGFL1, a synthetic peptide whose sequence is obtained from the first EGFL repeat of cyrA, functions independently of the cAMP-mediated signaling pathways to enhance cell motility through a mechanism involving Ca2+ signaling, CaM, and RasG. We show that DdEGFL1 increases the amounts of polymeric myosin II heavy chain and actin in the cytoskeleton by 24.1 ± 10.7% and 25.9 ± 2.1% respectively and demonstrate a link between Ca2+/CaM signaling and cytoskeletal dynamics. Finally, our findings suggest that carA and carC mediate a brake mechanism during chemotaxis since DdEGFL1 enhanced the movement of carA−/carC− cells by 844 ± 136% compared to only 106 ± 6% for parental DH1 cells. Based on our data, this signaling pathway also appears to involve the G-protein β subunit, RasC, RasGEFA, and protein kinase B. Together, our research provides insight into the functionality of EGFL repeats in Dictyostelium and the signaling pathways regulating cell movement in this model organism. It also identifies several mechanistic components of DdEGFL1-enhanced cell movement, which may ultimately provide a model system for understanding EGFL repeat function in higher organisms. 相似文献
20.
Alfredo Mijares Francisco Altamirano Juan Kolster José A. Adams José R. López 《Biochemical and biophysical research communications》2014
Duchenne muscular dystrophy (DMD) is a lethal X-inherited disease caused by dystrophin deficiency. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with a dilated cardiomyopathy that leads to progressive heart failure at the end of the second decade. The aim of the present study was to characterize the diastolic Ca2+ concentration ([Ca2+]d) and diastolic Na+ concentration ([Na+]d) abnormalities in cardiomyocytes isolated from 3-, 6-, 9-, and 12-month old mdx mice using ion-selective microelectrodes. In addition, the contributions of gadolinium (Gd3+)-sensitive Ca2+ entry and inositol triphosphate (IP3) signaling pathways in abnormal [Ca2+]d and [Na+]d were investigated. Our results showed an age-dependent increase in both [Ca2+]d and [Na+]d in dystrophic cardiomyocytes compared to those isolated from age-matched wt mice. Gd3+ treatment significantly reduced both [Ca2+]d and [Na+]d at all ages. In addition, blockade of the IP3-pathway with either U-73122 or xestospongin C significantly reduced ion concentrations in dystrophic cardiomyocytes. Co-treatment with U-73122 and Gd3+ normalized both [Ca2+]d and [Na+]d at all ages in dystrophic cardiomyocytes. These data showed that loss of dystrophin in mdx cardiomyocytes produced an age-dependent intracellular Ca2+ and Na+ overload mediated at least in part by enhanced Ca2+ entry through Gd3+ sensitive transient receptor potential channels (TRPC), and by IP3 receptors. 相似文献