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Pan Z, Avila A, Gollahon L. Paclitaxel induces apoptosis in breast cancer cells through different calcium--regulating mechanisms depending on external calcium conditions. Int J Mol Sci 2014; 15:2672-94. [PMID: 24549172 PMCID: PMC3958875 DOI: 10.3390/ijms15022672] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Revised: 02/10/2014] [Accepted: 02/11/2014] [Indexed: 12/19/2022] Open
Abstract
Previously, we reported that endoplasmic reticulum calcium stores were a direct target for paclitaxel initiation of apoptosis. Furthermore, the actions of paclitaxel attenuated Bcl-2 resistance to apoptosis through endoplasmic reticulum-mediated calcium release. To better understand the calcium-regulated mechanisms of paclitaxel-induced apoptosis in breast cancer cells, we investigated the role of extracellular calcium, specifically; whether influx of extracellular calcium contributed to and/or was necessary for paclitaxel-induced apoptosis. Our results demonstrated that paclitaxel induced extracellular calcium influx. This mobilization of extracellular calcium contributed to subsequent cytosolic calcium elevation differently, depending on dosage. Under normal extracellular calcium conditions, high dose paclitaxel induced apoptosis-promoting calcium influx, which did not occur in calcium-free conditions. In the absence of extracellular calcium an “Enhanced Calcium Efflux” mechanism in which high dose paclitaxel stimulated calcium efflux immediately, leading to dramatic cytosolic calcium decrease, was observed. In the absence of extracellular calcium, high dose paclitaxel’s stimulatory effects on capacitative calcium entry and apoptosis could not be completely restored. Thus, normal extracellular calcium concentrations are critical for high dose paclitaxel-induced apoptosis. In contrast, low dose paclitaxel mirrored controls, indicating that it occurs independent of extracellular calcium. Thus, extracellular calcium conditions only affect efficacy of high dose paclitaxel-induced apoptosis.
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Affiliation(s)
- Zhi Pan
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA.
| | - Andrew Avila
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA.
| | - Lauren Gollahon
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA.
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Jiang L, Bechtel MD, Bean JL, Winefield R, Williams TD, Zaidi A, Michaelis EK, Michaelis ML. Effects of gangliosides on the activity of the plasma membrane Ca2+-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1255-65. [PMID: 24434060 DOI: 10.1016/j.bbamem.2014.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 01/04/2014] [Accepted: 01/06/2014] [Indexed: 02/03/2023]
Abstract
Control of intracellular calcium concentrations ([Ca(2+)]i) is essential for neuronal function, and the plasma membrane Ca(2+)-ATPase (PMCA) is crucial for the maintenance of low [Ca(2+)]i. We previously reported on loss of PMCA activity in brain synaptic membranes during aging. Gangliosides are known to modulate Ca(2+) homeostasis and signal transduction in neurons. In the present study, we observed age-related changes in the ganglioside composition of synaptic plasma membranes. This led us to hypothesize that alterations in ganglioside species might contribute to the age-associated loss of PMCA activity. To probe the relationship between changes in endogenous ganglioside content or composition and PMCA activity in membranes of cortical neurons, we induced depletion of gangliosides by treating neurons with d-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (d-PDMP). This caused a marked decrease in the activity of PMCA, which suggested a direct correlation between ganglioside content and PMCA activity. Neurons treated with neuraminidase exhibited an increase in GM1 content, a loss in poly-sialoganglioside content, and a decrease in PMCA activity that was greater than that produced by d-PDMP treatment. Thus, it appeared that poly-sialogangliosides had a stimulatory effect whereas mono-sialogangliosides had the opposite effect. Our observations add support to previous reports of PMCA regulation by gangliosides by demonstrating that manipulations of endogenous ganglioside content and species affect the activity of PMCA in neuronal membranes. Furthermore, our studies suggest that age-associated loss in PMCA activity may result in part from changes in the lipid environment of this Ca(2+) transporter.
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Affiliation(s)
- Lei Jiang
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA; Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA.
| | - Misty D Bechtel
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA; Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA
| | - Jennifer L Bean
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA; Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS, USA
| | - Robert Winefield
- Structural Biology Center, University of Kansas, Lawrence, KS, USA
| | - Todd D Williams
- Structural Biology Center, University of Kansas, Lawrence, KS, USA
| | - Asma Zaidi
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA; Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA; Department of Biochemistry, Kansas City University of Medicine and Biosciences, Kansas City, MO, USA
| | - Elias K Michaelis
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA; Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA
| | - Mary L Michaelis
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA; Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA
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Watson HR, Butler J, Schuppe HJ, Lee AG, East JM. The localization of the ER retrieval sequence for the calcium pump SERCA1. Mol Membr Biol 2011; 28:216-26. [DOI: 10.3109/09687688.2011.572566] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Insulin induced translocation of Na+/K+ -ATPase is decreased in the heart of streptozotocin diabetic rats. Acta Pharmacol Sin 2009; 30:1616-24. [PMID: 19915586 DOI: 10.1038/aps.2009.162] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
AIM To investigate the effect of acute insulin administration on the subcellular localization of Na(+)/K(+)-ATPase isoforms in cardiac muscle of healthy and streptozotocin-induced diabetic rats. METHODS Membrane fractions were isolated with subcellular fractionation and with cell surface biotinylation technique. Na(+)/K(+)-ATPase subunit isoforms were analysed with ouabain binding assay and Western blotting. Enzyme activity was measured using 3-O-methylfluorescein-phosphatase activity. RESULTS In control rat heart muscle alpha1 isoform of Na(+)/K(+) ATPase resides mainly in the plasma membrane fraction, while alpha2 isoform in the intracellular membrane pool. Diabetes decreased the abundance of alpha1 isoform (25 %, P<0.05) in plasma membrane and alpha2 isoform (50%, P<0.01) in the intracellular membrane fraction. When plasma membrane fractions were isolated by discontinuous sucrose gradients, insulin-stimulated translocation of alpha2- but not alpha1-subunits was detected. Alpha1-subunit translocation was only detectable by cell surface biotinylation technique. After insulin administration protein level of alpha2 increased by 3.3-fold, alpha1 by 1.37-fold and beta1 by 1.51-fold (P<0.02) in the plasma membrane of control, and less than 1.92-fold (P<0.02), 1.19-fold (not significant) and 1.34-fold (P<0.02) in diabetes. The insulin-induced translocation was wortmannin sensitive. CONCLUSION This study demonstrates that insulin influences the plasma membrane localization of Na(+)/K(+)-ATPase isoforms in the heart. alpha2 isoform translocation is the most vulnerable to the reduced insulin response in diabetes. alpha1 isoform also translocates in response to insulin treatment in healthy rat. Insulin mediates Na(+)/K(+)-ATPase alpha1- and alpha2-subunit translocation to the cardiac muscle plasma membrane via a PI3-kinase-dependent mechanism.
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Assembly and dynamics of proteins of the longitudinal and junctional sarcoplasmic reticulum in skeletal muscle cells. Proc Natl Acad Sci U S A 2009; 106:4695-700. [PMID: 19261851 DOI: 10.1073/pnas.0810243106] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The sarcoplasmic reticulum (SR) of skeletal muscle cells is a complex network of tubules and cisternae that share a common lumen delimited by a single continuous membrane. The SR contains longitudinal and junctional domains characterized by distinctive patterns of protein localization, but how SR proteins reach and/or are retained at these sites is not known. Here, we report that the organization of longitudinal SR proteins is a slow process characterized by temporally distinct patterns of protein localization. In contrast, junctional SR proteins rapidly and synchronously assembled into clusters which, however, merged into mature triadic junctions only after completion of longitudinal SR protein organization. Fluorescence recovery after photobleaching experiments indicated that SR organization was accompanied by significant changes in the dynamic properties of longitudinal and junctional proteins. The decrease in mobility that accompanied organization of the longitudinal SR proteins ank1.5-GFP and GFP-InsP3R1 was abrogated by deletion of specific binding sites for myofibrillar or cytoskeletal proteins, respectively. Assembly of junctional SR domains was accompanied by a strong decrease in mobility of junctional proteins that in triadin appeared to be mediated by its intraluminal region. Together, the data suggest that the organization of specific SR domains results from a process of membrane reorganization accompanied by the establishment of multiple protein-protein interactions with intrinsic and extrinsic cues.
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Okkenhaug H, Weylandt KH, Carmena D, Wells DJ, Higgins CF, Sardini A. The human ClC‐4 protein, a member of the CLC chloride channel/transporter family, is localized to the endoplasmic reticulum by its N‐terminus. FASEB J 2006; 20:2390-2. [PMID: 17023393 DOI: 10.1096/fj.05-5588fje] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Despite considerable similarity in their amino acid sequences and structural features, the mammalian members of the CLC chloride channel/transporter family have different subcellular locations. The subcellular location and function of one of these members, hClC-4, is controversial. To characterize its cellular function, we investigated its tissue distribution and subcellular location. Expression was high in excitable tissues such as the nervous system and skeletal muscle. When heterologously expressed in HEK293 cells and in skeletal muscle fibers, hClC-4 localizes to the endoplasmic/sarcoplasmic reticulum (ER/SR) membranes, in contrast to hClC-3, which localizes to vesicular structures. This location was confirmed by identification of endogenous ClC-4 in membrane fractions from mouse brain homogenate enriched for the sarco-endoplasmic reticulum ATPase SERCA2, an ER/SR marker. To identify the motif responsible for ER localization of hClC-4, we generated hClC-4 truncations and chimeras between hClC-4 and hClC-3 or the unrelated plasma membrane protein Ly49E. A stretch of amino acids, residues 14-63, at the N-terminus constitutes a novel motif both necessary and sufficient for targeting hClC-4 and other membrane proteins to the ER.
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Affiliation(s)
- Hanneke Okkenhaug
- MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Hospital Campus, Du Cane Rd., London W12 0NN, UK
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Ebert AM, Hume GL, Warren KS, Cook NP, Burns CG, Mohideen MA, Siegal G, Yelon D, Fishman MC, Garrity DM. Calcium extrusion is critical for cardiac morphogenesis and rhythm in embryonic zebrafish hearts. Proc Natl Acad Sci U S A 2005; 102:17705-10. [PMID: 16314582 PMCID: PMC1308882 DOI: 10.1073/pnas.0502683102] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Indexed: 01/18/2023] Open
Abstract
Calcium entry into myocytes drives contraction of the embryonic heart. To prepare for the next contraction, myocytes must extrude calcium from intracellular space via the Na+/Ca2+ exchanger (NCX1) or sequester it into the sarcoplasmic reticulum, via the sarcoplasmic reticulum Ca2+-ATPase2 (SERCA2). In mammals, defective calcium extrusion correlates with increased intracellular calcium levels and may be relevant to heart failure and sarcoplasmic dysfunction in adults. We report here that mutation of the cardiac-specific NCX1 (NCX1h) gene causes embryonic lethal cardiac arrhythmia in zebrafish tremblor (tre) embryos. The tre ventricle is nearly silent, whereas the atrium manifests a variety of arrhythmias including fibrillation. Calcium extrusion defects in tre mutants correlate with severe disruptions in sarcomere assembly, whereas mutations in the L-type calcium channel that abort calcium entry do not produce this phenotype. Knockdown of SERCA2 activity by morpholino-mediated translational inhibition or pharmacological inhibition causes embryonic lethality due to defects in cardiac contractility and morphology but, in contrast to tre mutation, does not produce arrhythmia. Analysis of intracellular calcium levels indicates that homozygous tre embryos develop calcium overload, which may contribute to the degeneration of cardiac function in this mutant. Thus, the inhibition of NCX1h versus SERCA2 activity differentially affects the pathophysiology of rhythm in the developing heart and suggests that relative levels of NCX1 and SERCA2 function are essential for normal development.
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Affiliation(s)
- A M Ebert
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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Reiner DS, Hetsko ML, Meszaros JG, Sun CH, Morrison HG, Brunton LL, Gillin FD. Calcium signaling in excystation of the early diverging eukaryote, Giardia lamblia. J Biol Chem 2003; 278:2533-40. [PMID: 12397071 DOI: 10.1074/jbc.m208033200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Excystation of Giardia lamblia, which initiates infection, is a poorly understood but dramatic differentiation induced by physiological signals from the host. Our data implicate a central role for calcium homeostasis in excystation. Agents that alter cytosolic Ca(2+) levels (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-tetra(acetyloxymethyl) ester, a Ca(2+) channel blocker, Ca(2+) ionophores, and thapsigargin) strongly inhibit excystation. Treatment of Giardia with thapsigargin raised intracellular Ca(2+) levels, and peak Ca(2+) responses increased with each stage of excystation, consistent with the kinetics of inhibition. Fluorescent thapsigargin localized to a likely Ca(2+) storage compartment in cysts. The ability to sequester ions in membrane-bounded compartments is a hallmark of the eukaryotic cell. These studies support the existence of a giardial thapsigargin-sensitive Ca(2+) storage compartment resembling the sarcoplasmic/endoplasmic reticulum calcium ATPase pump-leak system and suggest that it is important in regulation of differentiation and appeared early in the evolution of eukaryotic cells. Calmodulin antagonists also blocked excystation. The divergent giardial calmodulin localized to the eight flagellar basal bodies/centrosomes, like protein kinase A. Inhibitor kinetics suggest that protein kinase A signaling triggers excystation, whereas calcium signaling is mainly required later, for parasite activation and emergence. Thus, the basal bodies may be a cellular control center to coordinate the resumption of motility and cytokinesis in excystation.
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Affiliation(s)
- David S Reiner
- Department of Pathology, University of California, San Diego, 92103, USA
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