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1.

001-es BibID:BIBFORM049403
Első szerző:Almássy János (élettanász, biológus, angol-magyar szakfordító)
Cím:Investigation of ryanodine receptor using peptide toxins / J. Almassy, S. Sarkozi, I. Jona
Dátum:2010
ISSN:0231-424X 1588-2683
Megjegyzések:Action potential of the skeletal muscle surface membrane leads to Ca2+ release from the sarcoplasmic reticulum evoked by direct coupling between dihydropyridine receptor (DHPR) and Ca2+ release channel (RyR). The structural basis of the allosteric connection is the intracellular loop between the 2nd and 3rd transmembrane repeat of the DHPR ?1 subunit. We previously showed that a ?-scorpion toxin maurocalcine (MCa) that shares primary sequence homology with the amino acid residues of DHPR-loop peptide essential for RyR activation raises single RyR channel open probability and blocks RyR in long lasting subconductive states These long lasting subconductance events characterised by mean event duration, which is about 12 secs for the wild type toxin. Using peptide where one charged amino acid (at a time) were replased with a neutral one ? wew showed that the critical amino acid is the 24th. Furtehrmore the strength of the toxin effect is proportional witht the distance of the muatted and of the 24th AA. The aimed to of this study was to confirm the hypothesis that MCa shares common binding sites with the DHPR loop peptide on RyR, and to characterize the potential effects of other MCa-homologue toxins (such as charybdotoxin (ChTx) and iberiotoxin (IbTx)) on RyR gating. Using single channel electrophysiology we demonstrated a competitive interaction between the loop peptide ? Mca and MCa ? ChTx respectively. We also found that ChTx albeit increased RyR open probability, induced long channel closures in dose-, and membrane potential- and Ca2+-dependent manner, but not in a use dependent fashion, while IbTx in spite of the significant homology was ineffective.
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
Megjelenés:Acta Physiologica Hungarica. - 97 : 3 (2010), p. 89. -
További szerzők:Sárközi Sándor (1966-) (élettanász) Jóna István (1948-) (élettanász, fizikus)
Pályázati támogatás:81923
OTKA
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2.

001-es BibID:BIBFORM049388
Első szerző:Almássy János (élettanász, biológus, angol-magyar szakfordító)
Cím:Inhibition of Ryr1 by different lanthanides might reveal fine details of the ion conducting pore / Janos Almassy, Zsanett Topcsiov, Anett Szabo, Istvan Jona
Dátum:2008
ISSN:0006-3495
Megjegyzések:Effect of Europium on the gating of the RyR1 was investigated using Müuller-type artificial bilayer system. Europium applied on the trans side inhibited the RyR1 channel by Kd = 4.7 ? 0.1 mM (similarly to the Gd3+ effect), with a high cooperativity, as characterized by a Hill-coefficient of N = 5.9 ? 0.9 in contrast to Gadolinium, which exhibited N= 4. Inhibition of the RyR1 activity from the cis side was also different from that of Gadolinium, characterized by Kd = 167 ? 5.0 nM and Nhill = 2.0 ? 0.1. The Eu3+ inhibition was potential independent if the charge carrier moved according to the physiological direction of calcium release, while it was potential dependent (and proportional with the driving force) if the current was opposite to the current during calcium release. We assume, that theEuropium binding site is in or near to channel pore because of voltage dependence of the Europium blockade. Effect of Europium was similar on the Ryanodine binding of HSR vesicles with slightlydifferent affinity probably due to the unspecific Europium binding by the associated junctional proteins. Ryanodine exerted its characteristic effect locking the channel into its half-conductance stateon the Europium modified channel independently that Europium was applied from the cis or from the trans side. A model explaining these data - considering the different ionic diameters for calcium,gadolinium and europium - is proposed to explain these findings and to propose further investigation of the ion conducting pore of the RyR1, based on the different ion-diameters of the lanthanides
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
Megjelenés:Biophysical Journal. - Volume 94 : Suppl. 2 (2008), p. 426a. -
További szerzők:Topcsiov Zsanett Szabó Anett (élettanász) Jóna István (1948-) (élettanász, fizikus)
Pályázati támogatás:T061442
OTKA
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3.

001-es BibID:BIBFORM049386
Első szerző:Almássy János (élettanász, biológus, angol-magyar szakfordító)
Cím:Effect of scorpion toxins on the CRC/RyR function / Janos Almassy, Balazs Lukacs, Sandor Sarkozi, Istvan Jona
Dátum:2012
ISSN:0006-3495
Megjegyzések:It was shown previously that maurocalcin (MCa) induces long lasting subconductance states (LLSS) investigating the RyR function by single channel electrophysiology. These LLSSs are polarity and potential dependent and caused by the distinct positively charged surface formed by 5 amino acids corresponding to the peptide A binding site. We tested the effect of beta scorpion toxins - having a similar structure - on the RyR1 function. Charibdotoxin (CHTX) elicits close state at 20 nM in an all or none and voltage dependent manner because of smaller surface charge. Smaller size makes it easier to reach the most inner toxin binding site (out of the three) which causes the closure of the channel. MCa and CHTX share a common binding site which is identical to the peptide A binding site. Noxiustoxin has a similar effect at slightly higher toxin concentration. At nanomolar concentration Kaliotoxin evokes "flickering" of the channel in subconductance state which is occasionally interrupted by long lasting closed states, while locks the channel in closed state at micromolar concentration. Iberiotoxin induces a slight increase of the open probability accompanied by normal gating while Slotoxin has no effect. With the exception of MCa all toxins are effective only at one side, at the preferred side. Iberiotoxin and Slotoxin - ion spite of similar structure - have no large positive surfaces, they exhibit random surface charge distribution. A model has been proposed for the possible mode of action which accounts for the above effect of the tested toxins. Supported by Hungarian Research Found OTKA 81923.1563-PosB333
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
Megjelenés:Biophysical Journal. - 102 : 3 (2012), p. 306a-307a. -
További szerzők:Lukács Balázs (1978-) (élettanász) Sárközi Sándor (1966-) (élettanász) Jóna István (1948-) (élettanász, fizikus)
Pályázati támogatás:81923
OTKA
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4.

001-es BibID:BIBFORM049412
Első szerző:Almássy János (élettanász, biológus, angol-magyar szakfordító)
Cím:Miocardial infarct induced changes of skeletal type SR calcium channel (RyR1) / J. Almássy, G. Vassort, I. Jóna
Dátum:2006
Megjegyzések:In heart failure (HF) skeletal muscle weakness and fatigue develop that could be explained by decreased Ca2+ content of the sarcoplasmic reticulum (SR) concomitant reduction of calcium transients' amplitude, indicating the impaired balance of calcium transport mechanisms. The aim of the present study was to identify putative functional RyR1 changes contributing to the reduced Ca2+ content of the SR.Single RyR1 Ca2+-release channels from rats with HF were reconstituted into planar lipid bilayer and gating behaviour of incorporated channels was studied under voltage-clamp conditions. 1/3 of these channels showed 40% higher conductance compared to RyRs from control rats and the voltage dependency of channel conductance altered, showing still ohmic but polarity dependent conductance characterized by 785 ? 28 pS for positive and 575 ? 31 pS for negative polarity. Altered Ca2+-dependency of channel activity was also observed on RyRs from HFafflicted rats, such as enhanced calcium activation and reduced calcium inhibition.
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
Megjelenés:Journal of Muscle Research and Cell Motility. - 27 (2006), p. 521. -
További szerzők:Vassort, Guy Jóna István (1948-) (élettanász, fizikus)
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5.

001-es BibID:BIBFORM004134
Első szerző:Almássy János (élettanász, biológus, angol-magyar szakfordító)
Cím:Effects of K-201 on the calcium pump and calcium release channel of rat skeletal muscle / Janos Almassy, Monika Sztretye, Balazs Lukacs, Beatrix Dienes, Laszlo Szabo, Peter Szentesi, Guy Vassort, Laszlo Csernoch, Istvan Jona
Dátum:2008
ISSN:0031-6768
Megjegyzések:The benzothiazepine derivative K-201 has been suggested as a potential therapeutic agent due to its antiarrhythmogenic action. To understand how the drug alters calcium release from the sarcoplasmic reticulum (SR), we investigated its effects on the SR calcium channel and calcium pump by single channel electrophysiology, whole-cell confocal microscopy, and ATPase activity measurements on control and post-myocardial infarcted (PMI) rat skeletal muscle. In bilayers, K-201 induced two subconductance states corresponding to approximately 24% (S(1)) and approximately 13% (S(2)) of the maximum conductance. Dependence of event frequency and of time spent in S(1) and S(2) on the drug concentration was biphasic both in control and in PMI rats, with a maximum at 50 microM. At this concentration, the channel spends 26 +/- 4% and 24 +/- 4%, respectively, of the total time in these subconductance states at positive potentials, while no subconductances are observed at negative potentials. K-201 altered the frequency of elementary calcium release events: spark frequency decreased from 0.039 +/- 0.001 to 0.023 +/- 0.001 s(-1) sarcomere(-1), while the frequency of embers increased from 0.011 +/- 0.001 to 0.023 +/- 0.001 s(-1) sarcomere(-1). Embers with different amplitude levels were observed after the addition of the drug. K-201 inhibited the Ca(2+) ATPase characterized by IC(50,contr) = 119 +/- 21 muM and n (Hill,contr) = 1.84 +/- 0.48 for control and IC(50,PMI) = 122 +/- 18 microM and n (Hill,PMI) = 1.97 +/- 0.24 for PMI animals. These results suggest that although K-201 would increase the appearance of subconductance states, the overall calcium release is reduced by the drug. In addition, the effect of K-201 is identical on calcium release channels from control and PMI rats.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Pflügers Archiv. - 457 : 1 (2008), p. 171-183. -
További szerzők:Sztretye Mónika (1981-) (élettanász, elektrofiziológus) Lukács Balázs (1978-) (élettanász) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) Szabó László (Románia) Szentesi Péter (1967-) (élettanász) Vassort, Guy Csernoch László (1961-) (élettanász) Jóna István (1948-) (élettanász, fizikus)
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6.

001-es BibID:BIBFORM001016
Első szerző:Altafaj, Xavier
Cím:Maurocalcine interacts with the cardiac ryanodine receptor without inducing channel modification / Altafaj X., France J., Almássy J., Jóna I., Rossi D., Sorrentino V., Mabrouk K., De Waard M., Ronjat M.
Dátum:2007
Megjegyzések:We have previously shown that MCa (maurocalcine), a toxin from the venom of the scorpion Maurus palmatus, binds to RyR1 (type 1 ryanodine receptor) and induces strong modifications of its gating behaviour. In the present study, we investigated the ability of MCa to bind to and modify the gating process of cardiac RyR2. By performing pull-down experiments we show that MCa interacts directly with RyR2with an apparent affinity of 150 nM. By expressing different domains of RyR2 in vitro, we show that MCa binds to two domains of RyR2, which are homologous with those previously identified on RyR1. The effect of MCa binding to RyR2 was then evaluated by three different approaches: (i) [H-3]ryanodine binding experiments, showing a very weak effect of MCa (up to 1 mu M), (ii) Ca2+ release measurements from cardiac sarcoplasmic reticulum vesicles, showing that MCa up to 1 mu M is unable to induce Ca2+ release, and (iii) single-channel recordings, showing that MCa has no effect on the open probability or on the RyR2 channel conductance level. Long-lasting opening events of RyR2 were observed in the presence of MCa only when the ionic current direction was opposite to the physiological direction, i.e. from the cytoplasmic face of RyR2 to its luminal face. Therefore, despite the conserved MCa binding ability of RyR1 and RyR2, functional studies show that, in contrast with what is observed with RyR1, MCa does not affect the gating properties of RyR2. These results highlight a different role of the MCa-binding domains in the gating process of RyR1 and RyR2.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Biochemical Journal 406 (2007), p. 309-315. -
További szerzők:France, Julien Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító) Jóna István (1948-) (élettanász, fizikus) Rossi, Daniela Sorrentino, Vincenzo Mabrouk, Kamel De Waard, Michel Ronjat, Michel
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7.

001-es BibID:BIBFORM004074
Első szerző:Birinyi Péter (élettanász)
Cím:The Na+/Ca2+ exchange blocker SEA0400 fails to enhance cytosolic Ca2+ transient and contractility in canine ventricular cardiomyocytes / Birinyi P., Tóth A., Jóna I., Acsai K., Almássy J., Nagy N., Prorok J., Gherasim I., Papp Z., Hertelendi Z., Szentandrássy N., Bányász T., Fülöp F., Papp J. G., Varró A., Nánási P. P., Magyar J.
Dátum:2008
Megjegyzések:Aims This study was designed to evaluate the effects of the Na+/Ca2+ exchange (NCX) inhibitor SEA0400 on Ca2+ handling in isolated canine ventricular myocytes. Methods and results Intracellular Ca2+ ([Ca2+](i)) transients, induced by either field stimulation or caffeine flush, were monitored using Ca2+ indicator dyes. [Ca2+](i)-dependent modulation of the inhibitory effect of SEA0400 on NCX was characterized by the changes in Ni2+-sensitive current in voltage-clamped myocytes. Sarcoplasmic reticulum (SR) Ca2+ release and uptake were studied in SIR membrane vesicles. Gating properties of single-ryanodine receptors were analysed in lipid bilayers. Ca2+ sensitivity of the contractile machinery was evaluated in chemically skinned myocytes. In myocytes paced at 1 Hz, neither diastolic [Ca2+](i) nor the amplitude of [Ca2+](i) transients was significantly altered by SEA0400 up to the concentration of 1 mu M, which was shown to inhibit the exchange current. The blocking effect of SEA0400 on NCX decreased with increasing [Ca2+](i), and it was more pronounced in reverse than in forward mode operation at every [Ca2+](i) examined. The rate of decay of the caffeine-induced [Ca2+](i) transients was decreased significantly by 1 mu M SEA0400; however, this effect was only a fraction of that observed with 10 mM NiCl2. Neither SR Ca2+ release and uptake nor cell shortening and Ca2+ sensitivity of the contractile proteins were influenced by SEA0400. Conclusion The lack of any major SEA0400-induced shift in Ca2+ transients or contractility of myocytes can well be explained by its limited inhibitory effect on NCX (further attenuated by elevated [Ca2+](i) levels) and a concomitant reduction in Ca2+ influx due to the predominantly reverse mode blockade of NCX and suppression of L-type Ca2+ current.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Cardiovascular Research. - 78 : 3 (2008), p. 476-484. -
További szerzők:Tóth András (farmakológus) Jóna István (1948-) (élettanász, fizikus) Acsai Károly Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító) Nagy Norbert (1977-) (kísérletes farmakológus) Prorok János Gherasim, Iuliana Papp Zoltán (1965-) (kardiológus, élettanász) Hertelendi Zita (1978-) (orvos) Szentandrássy Norbert (1976-) (élettanász) Bányász Tamás (1960-) (élettanász) Fülöp Ferenc Papp Gy. Julius (Szeged) Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász) Magyar János (1961-) (élettanász)
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8.

001-es BibID:BIBFORM049392
Első szerző:Csernoch László (élettanász)
Cím:The Low Affinity Calcium Buffer TPEN Alters Calcium Release From the Sarcoplasmic Reticulum (SR) of Mammalian Skeletal Muscle / Laszlo Csernoch, Cecilia Simut, János Almássy, Carole Jung, Ernst Niggli, István Jona
Dátum:2005
ISSN:0006-3495
Megjegyzések:Recent experiments suggested that chelating calcium within the SR using phosphate in the intracellular solution of skinned mammalian skeletal muscle fibers leads to the increase in the frequency of elementary calcium release events (ECRE) as observed under laser scanning confocal microscopy (Csernoch et al. 2003. Biophys. J. 84, 386a). To understand if this phenomenon was solely due to the buffering of intra SR calcium we incubated our saponin skinned, Fluo-4 loaded fibers with the low affinity membrane permeant buffer N,N,N',N'-tetrakis (2-pyridylmethyl)ethylene diamine (TPEN) and measured ECRE in the line-scan mode using a confocal scanner. In the concentration of 0.2 mM TPEN suppressed, rather than increased the frequency of ECRE sometimes to the point that no events were detectable. To determine whether this effect was due to chelating calcium or to a direct inhibition of ryanodine receptors (RyR1) by TPEN, the effects of the drug were studied on isolated RyR1-s incorporated into planar lipid bilayers. TPEN increased channel activity (open probability) at negative (cis compared to trans) holding potentials in a concentration and calcium dependent manner. In contrast, at positive holding potentials an inhibition was observed. Channel inhibition exhibited a voltage dependence resulting in a full inhibition at and above 40 mV. On the other hand, no potential dependence was observed when negative holding potentials were applied. In addition, the activity of the calcium pump was also inhibited by TPEN with a Kd of 639?44 ?M and a Hill coefficient of 0.87 ? 0.06. It is concluded that chelation alone of intra SR calcium will not increase ECRE frequency.This work was supported by OTKA T034894, T037727 and ETT 250/2003.
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
Megjelenés:Biophysical Journal. - 88 : Supplement 2 (2005), p. 636a. -
További szerzők:Simut, Cecilia Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító) Jung, Carole Niggli, Ernst Jóna István (1948-) (élettanász, fizikus)
Pályázati támogatás:T037727
OTKA
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9.

001-es BibID:BIBFORM049385
Első szerző:Csernoch László (élettanász)
Cím:Estimation of Pore Geometry of RyR1 using Lanthanide Ruler / Laszlo Csernoch, Janos Almassy, Sandor Sarkozi, Balazs Lukacs, Istvan Jona
Dátum:2012
ISSN:0006-3495
Megjegyzések:It was shown previously that the Ca analogue Gd inhibits RyR1 gating symmetrically with a Kd about 5.5 microM and Hill coefficient (nH) of 4 both on cis and trans side using single channel electrophysiology. We further tested the RyR1-lanthanide interaction using two lanthanides - having an ionic radii between Ca2+ and Gd3+ - by bilayer measurements and ryanodine binding experiments. Cis inhibition of RyR1 by Eu was characterized by a binding constant of Kd=167?5 nM and an nH of 2?0.1 while trans inhibition exhibits Kd=4.8?0.2 microM and nN of 5.2?1.2. The inhibition constants for Sm on the cis side are Kd=64.3?2.5 nM and nH=2.2?0.2 while on the trans side Kd=6.15?0.13 microM and nH=4.68?0.45. Inhibition by Eu and Sm are potential and polarity dependent in contrast to Gd due to the differences in ionic radii of these lanthanides. Increasing the ionic radius from 0.938 (Gd) to 0.964 (Sm) increased the binding affinity from 5.6 microM to 64.3 nM revealing that the size of Ca binding pocket is only slightly higher than the ionic radius of Sm. Ryanodine (Ry) binding experiments revealed that lanthanides bind - at least partially - to the regulatory Ca binding site because the dose response curve of 3H Ry binding starts with an increase of Ry binding, which amounts to about 40% for Eu and 70% for Sm of basic Ry binding. A model has been proposed for one possible spatial arrangement of lanthanide and calcium binding sites of the RyR1 pore based on the ionic radii of Ca and the tested lanthanides. Supported by OTKA 81923.1557-PosB327
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
Megjelenés:Biophysical Journal. - 102 : 3 Supplement (2012), p. 305a. -
További szerzők:Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító) Sárközi Sándor (1966-) (élettanász) Lukács Balázs (1978-) (élettanász) Jóna István (1948-) (élettanász, fizikus)
Pályázati támogatás:81923
OTKA
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10.

001-es BibID:BIBFORM080522
035-os BibID:(WOS)000480733000011 (Scopus)85071351221 (PMID)31337666
Első szerző:Diszházi Gyula (gyógyszerész)
Cím:Dantrolene Requires Mg2+ and ATP To Inhibit the Ryanodine Receptor / Gyula Diszházi, Zsuzsanna Édua Magyar, János András Mótyán, László Csernoch, István Jóna, Péter Pál Nánási, János Almássy
Dátum:2019
ISSN:0026-895X
Megjegyzések:Dantrolene is a ryanodine receptor (RyR) inhibitor, which is used to relax muscles in malignant hyperthermia syndrome. Although dantrolene binds to the RyR protein, its mechanism of action is unknown, mainly because of the controversial results showing that dantrolene inhibited Ca2+ release from intact fibers and sarcoplasmic reticulum (SR) vesicles, but failed to inhibit single RyR channel currents in bilayers. Accordingly, it was concluded that an important factor for dantrolene's action was lost during the purification procedure of RyR. Recently, Mg2+ was demonstrated to be the essential factor for dantrolene to inhibit Ca2+ release in skinned muscle fibers. The aim of the present study was confirm these results in Ca2+ release and bilayer experiments, using SR vesicles and solubilized channels, respectively. Our Ca2+ release experiments demonstrated that the effect of dantrolene and Mg2+ was cooperative and that ATP enhanced the inhibiting effect of dantrolene. Namely, 10 mu M dantrolene reduced RyR channel open probability by similar to 50% in the presence of 3 mM free Mg2+ and 1 mMATP, whereas channel activity further decreased to similar to 20% of control when [ATP] was increased to 2 mM. Our data provide important complementary information that supports the direct, Mg2+-dependent mechanism of dantrolene's action and suggests that dantrolene also requires ATP to inhibit RyR.
Tárgyszavak:idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Molecular Pharmacology. - 96 : 3 (2019), p. 401-407. -
További szerzők:Magyar Zsuzsanna Édua (1993-) (molekuláris biológus) Mótyán János András (1981-) (biokémikus, molekuláris biológus) Csernoch László (1961-) (élettanász) Jóna István (1948-) (élettanász, fizikus) Nánási Péter Pál (1956-) (élettanász) Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító)
Pályázati támogatás:PD112199
OTKA
K115397
OTKA
GINOP-2.3.2-15-2016-00040
GINOP
EFOP-3.6.2-16-2017-00006
EFOP
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11.

001-es BibID:BIBFORM060362
Első szerző:Geyer Nikolett
Cím:Bile acids activate ryanodine receptors in pancreatic acinar cells via a direct allosteric mechanism / Geyer Nikolett, Diszházi Gyula, Csernoch László, Jóna István, Almássy János
Dátum:2015
ISSN:0143-4160
Megjegyzések:The earliest critical event of pancreatitis is a long lasting high amplitude rise of intracellular Ca(2+) concentration of the acinar cell, which can be triggered by high concentration of bile acids. Although, Ca(2+)-release through ryanodine receptors (RyR) is involved in the process, the significance and the exact mechanism of bile acid's action on RyR has not been fully elucidated yet. Therefore, we aimed to test with various techniques and aspects whether bile acids exert a direct effect on RyR and SERCA pump. Our data show that taurocholic acid (TCA)-induced Ca(2+) release in pancreatic acinar cells was significantly reduced by the RyR antagonist dantrolene. Further, we show that TCA enhanced RyR's (3)H-ryanodine binding and triggered robust Ca(2+)-release from RyR-enriched vesicles in the pathologically relevant concentration range. RyR single channel current analysis demonstrated that 200?M TCA induced a 5-fold increase in the channel's open probability and caused a significant lengthening of the mean open time. TCA also suppressed Ca(2+)-uptake rate and ATP-ase activity of SERCA-enriched vesicles, but interestingly, failed to decrease Ca(2+) elimination rate in intact cells. Overall, our results strongly suggest that TCA opens RyR by an allosteric mechanism, which contribute significantly to bile acid-induced pathologic Ca(2+)-leak from the endoplasmic reticulum in pancreatic acinar cells.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
ryanodine receptor
SERCA
Calcium release
Pancreas
Bile acid
Megjelenés:Cell Calcium. - 58 : 2 (2015), p. 160-170. -
További szerzők:Diszházi Gyula (1992-) (gyógyszerész) Csernoch László (1961-) (élettanász) Jóna István (1948-) (élettanász, fizikus) Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító)
Pályázati támogatás:112199
OTKA
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DOI
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12.

001-es BibID:BIBFORM049402
Első szerző:Jóna István (élettanász, fizikus)
Cím:Effect of charybdotoxin and iberiotoxin on the ryanodine receptor - calcium channel / Istvan Jona, Janos Almassy
Dátum:2009
Megjegyzések:Action potential of the skeletal muscle surface membrane leads to Ca2+ release from the sarcoplasmic reticulum via direct coupling between dihydropyridine (DHP)- and Ca2+ release channels (RyR). The structural basis of the allosteric connection is the intracellular loop between the 2nd and 3rd transmembrane repeat of the DHPR ?1 subunit. We previously showed that a ?-scorpion toxin maurocalcine (MCa) that shares primary sequence homology with the amino acid residues of DHPR-loop peptide essential for RyR activation raises single RyR channel open probability and blocks RyR in long lasting subconductive states The aim of the present study was to confirm the hypothesis that MCa shares common binding sites with the DHPR loop peptide on RyR, and to characterize the potential effects of other MCa-homologue toxins (such as charybdotoxin (ChTx) and iberiotoxin (IbTx)) on RyR gating. Using single channel electrophysiology we demonstrated a competitive interaction between the loop peptide ? Mca and MCa ? ChTx respectively. We also found that ChTx albeit increased RyR open probability, induced long channel closures in dose-, and membrane potential- and Ca2+-dependent manner, but not in a use dependent fashion, while IbTx in spite of the significant homology was ineffective.
Tárgyszavak:Természettudományok Biológiai tudományok idézhető absztrakt
calcium release
Megjelenés:Journal of Physiological Sciences. - 9 : Suppl. 1 (2009), p. 252. -
További szerzők:Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító)
Internet cím:Szerző által megadott URL
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