The opening of the inositol 1,4,5-trisphosphate-sensitive Ca2+ channel in rat cerebellum is inhibited by caffeine

Brown, G. R.; Sayers, Lee G.; Kirk, Christopher J.; Michell, Robert H.; Michelangeli, F.

doi:10.1042/bj2820309

Cited by 102 publications

(78 citation statements)

References 28 publications

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“…Therefore, these cells were ideal to study the non-RyR effects of 4CmC on intracellular [Ca 2+ ] levels. Figure 3 shows the effects of 4CmC (1 mM) and caffeine (5 mM) on intracellular A small decrease in fluorescence due to caffeine quenching of Fluo-3 was observed, and this phenomenon has been reported in other studies [3].…”

Section: Resultssupporting

confidence: 79%

Commonly used ryanodine receptor activator, 4-chloro-m-cresol (4CmC), is also an inhibitor of SERCA Ca2+ pumps

Al-Mousa

Michelangeli

2009

Pharmacological Reports

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Abstract:4-Chloro-m-cresol (4CmC) is an extensively used activator of ryanodine receptors (RyRs). Studies have shown that 4CmC, at a concentration of 1 mM, is sufficient to cause Ca 2+ release through RyRs. Here, we show that mM concentrations of 4CmC also inhibit the sarcoplasmic-endoplasmic reticulum Ca 2+ -ATPase (SERCA), (IC 50 2-3mM) and cause Ca 2+ release. 4CmC also causes increased intracellular [Ca 2+ ] levels in COS-7 cells, which lack functional RyRs. Thus, any increase in [Ca 2+ ] levels associated with use of 4CmC (³ 1mM) could lead to non-specific Ca 2+ changes due to SERCA inhibition rather than RyR activation.

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Section: Resultssupporting

confidence: 79%

Commonly used ryanodine receptor activator, 4-chloro-m-cresol (4CmC), is also an inhibitor of SERCA Ca2+ pumps

Al-Mousa

Michelangeli

2009

Pharmacological Reports

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“…4A) and presence of 10 mM caffeine (Fig. 4B), an inhibitor of the IP 3 receptor (35)(36)(37)(38). Inhibition of the IP 3 receptor therefore had no effect on capacitative Ca 2ϩ entry in COS-1 cells.…”

Section: Effect Of Overexpressing Pmr1 On Capacitative Camentioning

confidence: 99%

Baseline Cytosolic Ca2+ Oscillations Derived from a Non-endoplasmic Reticulum Ca2+Store

Missiaen¹,

Acker²,

Parys³

et al. 2001

Journal of Biological Chemistry

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) is an intracellular second messenger used by many cells to release Ca 2ϩ from their internal stores (6). IP 3 acts on the IP 3 receptor, which is an important Ca 2ϩ release channel in the endoplasmic reticulum (7). There is, however, increasing evidence that IP 3 receptors are also localized in the Golgi apparatus (8 -12). The role of this latter organelle in the generation of cytosolic Ca 2ϩ signals is not well known, partly because the mechanism by which the Golgi complex takes up Ca 2ϩ is less well understood compared with the Ca 2ϩ transport into the endoplasmic reticulum mediated by the sarco(endo)plasmic reticulum Ca 2ϩ -ATPase (SERCA). The Golgi apparatus expresses a specific Ca 2ϩ pump belonging to the Pmr1 family of Ca 2ϩ -transport ATPases (13). Pmr1 is insensitive to the inhibitor thapsigargin (14), in contrast to the SERCA Ca 2ϩ pumps in the sarco-and endoplasmic reticulum (15).We expressed the Pmr1 Ca 2ϩ pump of Caenorhabditis elegans (12) in COS-1 cells and pretreated the cells with thapsigargin to prevent SERCA-mediated Ca 2ϩ uptake in the endoplasmic reticulum. We demonstrate that a Ca 2ϩ store filled by the Pmr1 Ca 2ϩ pump and probably belonging to the Golgi compartment can set up baseline Ca 2ϩ spiking. EXPERIMENTAL PROCEDURESCell Culture and Transfection-COS-1 cells and HeLa cells were cultured as described previously (12, 16). The culture medium was replaced every 2 to 3 days. The cells were plated at a density of 2500 cells/cm 2 in Coverglass Chambers (Nunc Inc., Naperville, IL) or at a density of 10,000 cells/cm 2 in 12-well clusters (Costar, MA). Four days after plating, COS-1 cells were transiently transfected with Pmr1 from C. elegans or with the rabbit SERCA1a in pMT2 vector and investigated 3 days later (12). The full-length rabbit SERCA1a clone was kindly provided by Drs. J. P. Andersen and B. Vilsen (Department of Physiology, University of Aarhus, Denmark). Some cells were transfected with pig SERCA2a or SERCA2b in pSV57 (17).Immunofluorescence-Immunofluorescence microscopy was done as described previously (12). The primary antiserum Celpmrloop against Pmr1 was raised against a recombinant protein corresponding to the putative large cytoplasmic loop between transmembrane segments 4 and 5 of Pmr1 from C. elegans (12). The primary antiserum 809-27 against rabbit SERCA1 was kindly provided by Dr. J. Møller (Department of Biophysics, University of Aarhus, Denmark) (18). The antiserum against SERCA2a was described previously (19). The antibody against the 58K protein of the Golgi apparatus (clone 58K-9) was purchased from Abcams (Cambridge, UK).45 Ca 2ϩ Uptake-Fluxes were performed on saponin-permeabilized cells at 25°C as described previously (20). The cells were permeabilized by treating them for 10 min with 20 g/ml saponin at 25°C in a medium containing 120 mM KCl, 30 mM imidazole-HCl (pH 6.8), 2 mM MgCl 2 , 1 mM ATP and 1 mM EGTA. The non-mitochondrial Ca 2ϩ stores were loaded for 45 min in loading medium containing 120 mM KCl, 30 mM imidazole-HCl (pH 6.8), 5 mM MgCl 2 , 5 mM ATP, ...

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“…Persuasive evidence suggests that Ca 2þ release by RyR may be terminated before Ca 2þ stores are entirely depleted because luminal Ca 2þ is required to maintain RyR activity (Györke and Györke 1998;Launikonis et al 2006;Jiang et al 2008), possibly via its interaction with calsequestrin, a luminal high-capacity Ca 2þ -binding protein (Launikonis et al 2006;Terentyev et al 2006). A similar scheme has been proposed to account for two features of IP 3 -evoked Ca 2þ release: the initiation of Ca 2þ release after the quiescent interspike interval during repetitive Ca 2þ spikes (Berridge 2007) and quantal Ca 2þ release via IP 3 R. The latter describes the situation wherein unidirectional Ca 2þ efflux from intracellular stores terminates before the stores have fully emptied after stimulation with submaximally effective concentrations of IP 3 without loss of their ability to respond to a further increase in IP 3 concentration (Muallem et al 1989;Meyer and Stryer 1990;Taylor and Potter 1990;Oldershaw et al 1991;Bootman et al 1992;Brown et al 1992;Combettes et al 1992;Ferris et al 1992;Hirota et al 1995). The proposal is that luminal Ca 2þ sets the gain on the regulation by cytosolic IP 3 and Ca 2þ , so that as the luminal free Ca 2þ concentration falls, it causes the sensitivity of the IP 3 R to IP 3 to fall until, as Ca 2þ leaks from the ER, the IP 3 R closes despite the continued presence of cytosolic IP 3 and residual Ca 2þ within the ER (Irvine 1990).…”

Section: Regulation Of Ip 3 Receptors By Ca 2þ and Ipmentioning

confidence: 99%

IP3 Receptors: Toward Understanding Their Activation

Taylor¹,

Tovey²

2010

Cold Spring Harbor Perspectives in Biology

260

190

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Inositol 1,4,5-trisphosphate receptors (IP 3 R) and their relatives, ryanodine receptors, are the channels that most often mediate Ca 2þ release from intracellular stores. Their regulation by Ca 2þ allows them also to propagate cytosolic Ca 2þ signals regeneratively. This brief review addresses the structural basis of IP 3 R activation by IP 3 and Ca 2þ . IP 3 initiates IP 3 R activation by promoting Ca 2þ binding to a stimulatory Ca 2þ -binding site, the identity of which is unresolved. We suggest that interactions of critical phosphate groups in IP 3 with opposite sides of the clam-like IP 3 -binding core cause it to close and propagate a conformational change toward the pore via the adjacent N-terminal suppressor domain. The pore, assembled from the last pair of transmembrane domains and the intervening pore loop from each of the four IP 3 R subunits, forms a structure in which a luminal selectivity filter and a gate at the cytosolic end of the pore control cation fluxes through the IP 3 R.

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The opening of the inositol 1,4,5-trisphosphate-sensitive Ca2+ channel in rat cerebellum is inhibited by caffeine

Cited by 102 publications

References 28 publications

Commonly used ryanodine receptor activator, 4-chloro-m-cresol (4CmC), is also an inhibitor of SERCA Ca2+ pumps

Commonly used ryanodine receptor activator, 4-chloro-m-cresol (4CmC), is also an inhibitor of SERCA Ca2+ pumps

Baseline Cytosolic Ca2+ Oscillations Derived from a Non-endoplasmic Reticulum Ca2+Store

IP3 Receptors: Toward Understanding Their Activation

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