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McElroy SP, Drummond RM, Gurney AM. Regulation of store-operated Ca2+ entry in pulmonary artery smooth muscle cells. Cell Calcium 2009; 46:99-106. [DOI: 10.1016/j.ceca.2009.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 05/05/2009] [Accepted: 05/31/2009] [Indexed: 11/25/2022]
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Lange K, Gartzke J. F-actin-based Ca signaling-a critical comparison with the current concept of Ca signaling. J Cell Physiol 2006; 209:270-87. [PMID: 16823881 DOI: 10.1002/jcp.20717] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A short comparative survey on the current idea of Ca signaling and the alternative concept of F-actin-based Ca signaling is given. The two hypotheses differ in one central aspect, the mechanism of Ca storage. The current theory rests on the assumption of Ca-accumulating endoplasmic/sarcoplasmic reticulum-derived vesicles equipped with an ATP-dependent Ca pump and IP3- or ryanodine-sensitive channel-receptors for Ca-release. The alternative hypothesis proceeds from the idea of Ca storage at the high-affinity binding sites of actin filaments. Cellular sites of F-actin-based Ca storage are microvilli and the submembrane cytoskeleton. Several specific features of Ca signaling such as store-channel coupling, quantal Ca release, spiking and oscillations, biphasic and "phasic" uptake kinetics, and Ca-induced Ca release (CICR), which are not adequately described by the current concept, are inherent properties of the F-actin system and its dynamic state of treadmilling.
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Wang Z, Ramanadham S, Ma ZA, Bao S, Mancuso DJ, Gross RW, Turk J. Group VIA phospholipase A2 forms a signaling complex with the calcium/calmodulin-dependent protein kinase IIbeta expressed in pancreatic islet beta-cells. J Biol Chem 2005; 280:6840-9. [PMID: 15576376 PMCID: PMC3716912 DOI: 10.1074/jbc.m405287200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-secreting pancreatic islet beta-cells express a Group VIA Ca(2+)-independent phospholipase A(2) (iPLA(2)beta) that contains a calmodulin binding site and protein interaction domains. We identified Ca(2+)/calmodulin-dependent protein kinase IIbeta (CaMKIIbeta) as a potential iPLA(2)beta-interacting protein by yeast two-hybrid screening of a cDNA library using iPLA(2)beta cDNA as bait. Cloning CaMKIIbeta cDNA from a rat islet library revealed that one dominant CaMKIIbeta isoform mRNA is expressed by adult islets and is not observed in brain or neonatal islets and that there is high conservation of the isoform expressed by rat and human beta-cells. Binary two-hybrid assays using DNA encoding this isoform as bait and iPLA(2)beta DNA as prey confirmed interaction of the enzymes, as did assays with CaMKIIbeta as prey and iPLA(2)beta bait. His-tagged CaMKIIbeta immobilized on metal affinity matrices bound iPLA(2)beta, and this did not require exogenous calmodulin and was not prevented by a calmodulin antagonist or the Ca(2+) chelator EGTA. Activities of both enzymes increased upon their association, and iPLA(2)beta reaction products reduced CaMKIIbeta activity. Both the iPLA(2)beta inhibitor bromoenol lactone and the CaMKIIbeta inhibitor KN93 reduced arachidonate release from INS-1 insulinoma cells, and both inhibit insulin secretion. CaMKIIbeta and iPLA(2)beta can be coimmunoprecipitated from INS-1 cells, and forskolin, which amplifies glucose-induced insulin secretion, increases the abundance of the immunoprecipitatable complex. These findings suggest that iPLA(2)beta and CaMKIIbeta form a signaling complex in beta-cells, consistent with reports that both enzymes participate in insulin secretion and that their expression is coinduced upon differentiation of pancreatic progenitor to endocrine progenitor cells.
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Affiliation(s)
- Zhepeng Wang
- Mass Spectrometry Resource, Washington University School of Medicine, St. Louis, Missouri 63110
- Divisions of Endocrinology, Diabetes, and Metabolism, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sasanka Ramanadham
- Mass Spectrometry Resource, Washington University School of Medicine, St. Louis, Missouri 63110
- Divisions of Endocrinology, Diabetes, and Metabolism, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Zhongmin Alex Ma
- Division of Experimental Diabetes and Aging, Mount Sinai School of Medicine, New York, New York 10029
| | - Shunzhong Bao
- Mass Spectrometry Resource, Washington University School of Medicine, St. Louis, Missouri 63110
- Divisions of Endocrinology, Diabetes, and Metabolism, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - David J. Mancuso
- Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Chemistry, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Richard W. Gross
- Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Chemistry, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - John Turk
- Mass Spectrometry Resource, Washington University School of Medicine, St. Louis, Missouri 63110
- Divisions of Endocrinology, Diabetes, and Metabolism, Washington University School of Medicine, St. Louis, Missouri 63110
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
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ATP regulates anion channel-mediated organic osmolyte release from cultured rat astrocytes via multiple Ca2+-sensitive mechanisms. Am J Physiol Cell Physiol 2004; 288:C204-13. [PMID: 15371260 DOI: 10.1152/ajpcell.00330.2004] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ubiquitously expressed volume-regulated anion channels (VRACs) are activated in response to cell swelling but may also show limited activity in nonswollen cells. VRACs are permeable to inorganic anions and small organic osmolytes, including the amino acids aspartate, glutamate, and taurine. Several recent reports have demonstrated that neurotransmitters or hormones, such as ATP and vasopressin, induce or strongly potentiate astrocytic whole cell Cl(-) currents and amino acid release, which are inhibited by VRAC blockers. In the present study, we explored the intracellular signaling mechanisms mediating the effects of ATP on d-[(3)H]aspartate release via the putative VRAC pathway in rat primary astrocyte cultures. Cells were exposed to moderate (5%) or substantial (30%) reductions in medium osmolarity. ATP strongly potentiated d-[(3)H]aspartate release in both moderately swollen and substantially swollen cells. These ATP effects were blocked (>or=80% inhibition) by intracellular Ca(2+) chelation with BAPTA-AM, calmodulin inhibitors, or a combination of the inhibitors of protein kinase C (PKC) and calmodulin-dependent kinase II (CaMK II). In contrast, control d-[(3)H]aspartate release activated by the substantial hyposmotic swelling showed little (<or=25% inhibition) sensitivity to the same pharmacological agents. These data indicate that ATP regulates VRAC activity via two separate Ca(2+)-sensitive signaling cascades involving PKC and CaMK II and that cell swelling per se activates VRACs via a separate Ca(2+)/calmodulin-independent signaling mechanism. Ca(2+)-dependent organic osmolyte release via VRACs may contribute to the physiological functions of these channels in the brain, including astrocyte-to-neuron intercellular communication.
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López-González I, De La Vega-Beltrán JL, Santi CM, Florman HM, Felix R, Darszon A. Calmodulin antagonists inhibit T-type Ca(2+) currents in mouse spermatogenic cells and the zona pellucida-induced sperm acrosome reaction. Dev Biol 2001; 236:210-9. [PMID: 11456455 DOI: 10.1006/dbio.2001.0314] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The sperm acrosome reaction (AR) is a regulated exocytotic process required for gamete fusion. It depends on an increase in [Ca(2+)](i) mediated by Ca(2+) channels. Although calmodulin (CaM) has been reported to regulate several events during the AR, it is not known whether it modulates sperm Ca(2+) channels. In the present study we analyzed the effects of CaM antagonists W7 and trifluoroperazine on voltage-dependent T-type Ca(2+) currents in mouse spermatogenic cells and on the zona pellucida-induced AR in sperm. We found that these CaM antagonists decreased T-currents in a concentration-dependent manner with IC(50) values of approximately 10 and approximately 12 microM, respectively. W7 altered the channels' voltage dependence of activation and slowed both activation and inactivation kinetics. It also induced inactivation at voltages at which T-channels are not activated, suggesting a promotion of inactivation from the closed state. Consistent with this, W7 inhibited the ZP-induced [Ca(2+)](i) transients in capacitated sperm. Likewise, W7 and TFP inhibited the AR with an IC(50) of approximately 10 microM. In contrast, inhibitors of CaM-dependent kinase II and protein kinase A, as well as a CaM-activated phosphatase, had no effect either on T-currents in spermatogenic cells or on the sperm AR. Together these results suggest a functional interaction between CaM and the sperm T-type Ca(2+) channel. They are also consistent with the involvement of T-channels in the AR.
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Affiliation(s)
- I López-González
- Department of Genetics and Molecular Physiology, Institute of Biotechnology, UNAM, Mexico
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