151
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Wu X, Babnigg G, Zagranichnaya T, Villereal ML. The role of endogenous human Trp4 in regulating carbachol-induced calcium oscillations in HEK-293 cells. J Biol Chem 2002; 277:13597-608. [PMID: 11830588 DOI: 10.1074/jbc.m110881200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We utilized 2-aminoethyoxydiphenyl borane, an agent that blocks store-operated Ca(2+) entry, as well as an antisense approach to characterize endogenous Ca(2+) entry pathways in HEK-293 cells. The thapsigargin- and carbachol-induced, but not the 1-oleolyl-2-acytyl-sn-glycerol (OAG)-induced, entry was blocked by 2-aminoethyoxydiphenyl borane. Both reverse transcriptase-PCR and Western blot analyses demonstrated endogenous expression for HTRP1, HTRP3, and HTRP4 and specific suppression of mRNA levels and Trp protein levels in cells stably expressing antisense constructs. Expression of HTRP4 antisense inhibited 35% of the carbachol (CCh)-stimulated Ba(2+) entry and 46% of the OAG-stimulated Sr(2+) entry but in contrast had no effect on the thapsigargin-stimulated Ba(2+) or Sr(2+) entry. HTRP3 antisense reduced, while HTRP1 antisense had no effect on, OAG-induced Sr(2+) entry. Of greater importance, HTRP4 antisense expression, but not HTRP3 antisense expression, blocked the sustained Ca(2+) oscillations produced by low doses of CCh (15 microm), arguing that receptor-stimulated rather than store-operated channels are involved in these sustained oscillations. HTRP4 antisense also inhibited 75% of the arachidonic acid-induced Ca(2+) entry. In summary, these data suggest that HTRP4 proteins in HEK-293 cells, differing from HTRP3 and HTRP1 proteins, do not serve as functional subunits of store-operated channels but do function as subunits for CCh- and OAG-stimulated channels. Furthermore, evidence is provided for the first time for the involvement of a Trp isoform (HTRP4) in the formation of the channel responsible for both arachidonic acid-induced Ca(2+) entry and the Ca(2+) entry needed to sustain long term Ca(2+) oscillations induced by low doses of carbachol.
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Affiliation(s)
- Xiaoyan Wu
- Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, Chicago, Illinois 60637, USA
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152
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Talon S, Vallot O, Huchet-Cadiou C, Lompré AM, Léoty C. IP(3)-induced tension and IP(3)-receptor expression in rat soleus muscle during postnatal development. Am J Physiol Regul Integr Comp Physiol 2002; 282:R1164-73. [PMID: 11893622 DOI: 10.1152/ajpregu.00073.2001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was designed to examine whether changes in Ca(2+) release by inositol-1,4,5-trisphosphate (IP(3)) in 8-, 15-, and 30-day-old rat skeletal muscles could be associated with the expression of IP(3) receptors. Experiments were conducted in slow-twitch muscle in which both IP(3)-induced Ca(2+) release and IP(3)-receptor (IP(3)R) expression have been shown to be larger than in fast-twitch muscle. In saponin-skinned fibers, IP(3) induced transient contractile responses in which the amplitude was dependent on the Ca(2+)-loading period with the maximal IP(3) contracture being at 20 min of loading. The IP(3) tension decreased during postnatal development, was partially inhibited by ryanodine (100 microM), and was blocked by heparin (20-400 microg/ml). Amplification of the DNA sequence encoding for IP(3)R isoforms (using the RT-PCR technique) showed that in slow-twitch muscle, the type 2 isoform is mainly expressed, and its level decreases during postnatal development in parallel with changes in IP(3) responses in immature fibers. IP(3)-induced Ca(2+) release would then have greater participation in excitation-contraction coupling in developing fibers than in mature muscle.
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MESH Headings
- Age Factors
- Animals
- Anticoagulants/pharmacology
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Detergents
- Gene Expression/physiology
- Heparin/pharmacology
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate Receptors
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle, Skeletal/cytology
- Muscle, Skeletal/growth & development
- Muscle, Skeletal/metabolism
- Octoxynol
- Phosphodiesterase Inhibitors/pharmacology
- RNA, Messenger/analysis
- Rats
- Rats, Wistar
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Ryanodine/pharmacology
- Ryanodine Receptor Calcium Release Channel/genetics
- Sarcoplasmic Reticulum/metabolism
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Affiliation(s)
- Sophie Talon
- Laboratoire de Physiologie Générale, Unité Mixte de Recherche 6018 du Centre National de la Recherche Scientifique, Faculté des Sciences et des Techniques, Université de Nantes, F-44322 Nantes, Cedex 03, France
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153
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Yamaguchi M. Chapter 4 Impact of aging on calcium channels and pumps. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1566-3124(02)10016-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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154
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Abstract
ATP2A2, the gene that is abnormal in Darier's disease, encodes SERCA2, a calcium pump that is expressed in many tissues. The wide expression of SERCA2 might suggest that ATP2A2 mutations would cause a multisystem disease. There is however, no evidence of consistent extracutaneous manifestations of Darier's disease. We have conducted preliminary studies in patients with Darier's disease, in two extracutaneous systems in which SERCA2 is known to be important, in order to investigate whether subtle defects have been overlooked. We found no evidence for altered cardiac function in 10 patients using two-dimensional, colour and Doppler echocardiography. There were no consistent defects in platelet function in 12 patients, using bleeding time and aggregation studies. We conclude that the skin is sensitive to defects in SERCA2 function to which other systems appear robust.
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Affiliation(s)
- S Tavadia
- Department of Dermatology, Royal Infirmary, Castle Street, Glasgow G4 OSF, UK.
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155
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Sano Y, Inamura K, Miyake A, Mochizuki S, Yokoi H, Matsushime H, Furuichi K. Immunocyte Ca2+ influx system mediated by LTRPC2. Science 2001; 293:1327-30. [PMID: 11509734 DOI: 10.1126/science.1062473] [Citation(s) in RCA: 349] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We characterized an activation mechanism of the human LTRPC2 protein, a member of the transient receptor potential family of ion channels, and demonstrated that LTRPC2 mediates Ca2+ influx into immunocytes. Intracellular pyrimidine nucleotides, adenosine 5'-diphosphoribose (ADPR), and nicotinamide adenine dinucleotide (NAD), directly activated LTRPC2, which functioned as a Ca2+-permeable nonselective cation channel and enabled Ca2+ influx into cells. This activation was suppressed by intracellular adenosine triphosphate. These results reveal that ADPR and NAD act as intracellular messengers and may have an important role in Ca2+ influx by activating LTRPC2 in immunocytes.
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Affiliation(s)
- Y Sano
- Molecular Medicine Laboratories, Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., 21 Miyukigaoka, Tsukuba, Ibaraki 305-8585, Japan.
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156
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Putney JW, Broad LM, Braun FJ, Lievremont JP, Bird GS. Mechanisms of capacitative calcium entry. J Cell Sci 2001; 114:2223-9. [PMID: 11493662 DOI: 10.1242/jcs.114.12.2223] [Citation(s) in RCA: 399] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Capacitative Ca2+ entry involves the regulation of plasma membrane Ca2+ channels by the filling state of intracellular Ca2+ stores in the endoplasmic reticulum (ER). Several theories have been advanced regarding the mechanism by which the stores communicate with the plasma membrane. One such mechanism, supported by recent findings, is conformational coupling: inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) receptors in the ER may sense the fall in Ca2+ levels through Ca2+-binding sites on their lumenal domains, and convey this conformational information directly by physically interacting with Ca2+ channels in the plasma membrane. In support of this idea, in some cell types, store-operated channels in excised membrane patches appear to depend on the presence of both Ins(1,4,5)P3 and Ins(1,4,5)P3 receptors for activity; in addition, inhibitors of Ins(1,4,5)P3 production that either block phospholipase C or inhibit phosphatidylinositol 4-kinase can block capacitative Ca2+ entry. However, the electrophysiological current underlying capacitative Ca2+ entry is not blocked by an Ins(1,4,5)P3 receptor antagonist, and the blocking effects of a phospholipase C inhibitor are not reversed by the intracellular application of Ins(1,4,5)P3. Furthermore, cells whose Ins(1,4,5)P3 receptor genes have been disrupted can nevertheless maintain their capability to activate capacitative Ca2+ entry channels in response to store depletion. A tentative conclusion is that multiple mechanisms for signaling capacitative Ca2+ entry may exist, and involve conformational coupling in some cell types and perhaps a diffusible signal in others.
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Affiliation(s)
- J W Putney
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, Research Triangle, Park, NC 27709, USA.
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157
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Weirich J, Seiler L, Hug MJ, Fleckenstein-Grün G. Ca(2+) entry into primary cultured pig coronary smooth muscle cells after previous store depletion by repetitive P2Y purinoceptor stimulation. Cell Calcium 2001; 29:359-67. [PMID: 11292392 DOI: 10.1054/ceca.2001.0198] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Store-operated Ca(2+) entry, stimulated by depletion of intracellular Ca(2+) pools, has not been fully elucidated in vascular smooth muscle cells of pig coronary arteries. Therefore, [Ca(2+)](i) was measured in cultured cells derived from extramural pig coronary arteries using the Fura-2/AM fluorometry. Divalent cation entry was visualized with the Fura-2 Mn(2+)-quenching technique. Ca(2+) stores were depleted either by repetitive stimulation of P2Y purinoceptors with ATP (10 micromol/L), or by the sarcoendoplasmic Ca(2+)-ATPase inhibitor 2,5-Di-(tert-butyl)-1,4-benzohydroquinone (BHQ; 1 micromol/L) in Ca(2+)-free medium (EGTA 1 mmol/L). Addition of Ca(2+)(1 mmol/L) induced refilling of ATP-sensitive Ca(2+) stores and an increase in [Ca(2+)](i) in the presence of BHQ. Both could be significantly diminished by Ni(2+)(5 and 1mmol/L), La(3+)(10 micromol/L), Gd(3+)(10 micromol/L), and Mg(2+)(5.1 mmol/L). In contrast to the BHQ-mediated rise in [Ca(2+)](i), refilling of ATP-depleted stores was affected by neither flufenamate (0.1 mmol/L), nor by nitrendipine, nifedipine, and nisoldipine (each 1 micromol/L). The data suggest that after store depletion in pig coronary smooth muscle cells ATP and BHQ may converge on a common, Ni(2+)-, La(3+)-, Gd(3+)-, and Mg(2+)- sensitive Ca(2+) entry pathway, i.e. on a store-operated Ca(2+) entry. An additional contribution of the Na(+)/Ca(2+) exchanger cannot be excluded. Flufenamate-sensitive non-selective cation channels and dihydropyridine-sensitive L-type Ca(2+) channels are not involved in refilling of Ca(2+) stores after previous depletion by repetitive P2Y purinoceptor stimulation. The store-operated Ca(2+) entry in-between repetitive purinoceptor stimulation, i.e. in the absence of the agonist, may be responsible for the maintenance of agonist-induced rhythmic Ca(2+) responses.
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Affiliation(s)
- J Weirich
- Department of Physiology, University Freiburg i. Br, Germany
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158
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Laitinen PJ, Brown KM, Piippo K, Swan H, Devaney JM, Brahmbhatt B, Donarum EA, Marino M, Tiso N, Viitasalo M, Toivonen L, Stephan DA, Kontula K. Mutations of the cardiac ryanodine receptor (RyR2) gene in familial polymorphic ventricular tachycardia. Circulation 2001; 103:485-90. [PMID: 11157710 DOI: 10.1161/01.cir.103.4.485] [Citation(s) in RCA: 436] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Familial polymorphic ventricular tachycardia is an autosomal-dominant, inherited disease with a relatively early onset and a mortality rate of approximately 30% by the age of 30 years. Phenotypically, it is characterized by salvoes of bidirectional and polymorphic ventricular tachycardias in response to vigorous exercise, with no structural evidence of myocardial disease. We previously mapped the causative gene to chromosome 1q42-q43. In the present study, we demonstrate that patients with familial polymorphic ventricular tachycardia have missense mutations in the cardiac sarcoplasmic reticulum calcium release channel (ryanodine receptor type 2 [RyR2]). METHODS AND RESULTS In 3 large families studied, 3 different RyR2 mutations (P2328S, Q4201R, V4653F) were detected and shown to fully cosegregate with the characteristic arrhythmic phenotype. These mutations were absent in the nonaffected family members and in 100 healthy controls. In addition to identifying 3 causative mutations, we identified a number of single nucleotide polymorphisms that span the genomic structure of RyR2 and will be useful for candidate-based association studies for other arrhythmic disorders. CONCLUSIONS Our data illustrate that mutations of the RyR2 gene cause at least one variety of inherited polymorphic tachycardia. These findings define a new entity of disorders of myocardial calcium signaling.
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Affiliation(s)
- P J Laitinen
- Department of Medicine, University of Helsinki, Helsinki, Finland
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