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001-es BibID:BIBFORM031848
035-os BibID:PMID:20713548 WOS:000284828600009
Első szerző:Royer, Leandro (kutató)
Cím:Paradoxical buffering of calcium by calsequestrin demonstrated for the calcium store of skeletal muscle / Leandro Royer, Monika Sztretye, Carlo Manno, Sandrine Pouvreau, Jingsong Zhou, Bjorn C. Knollmann, Feliciano Protasi, Paul D. Allen, Eduardo Ríos
Dátum:2010
ISSN:0022-1295
Megjegyzések:Contractile activation in striated muscles requires a Ca(2+) reservoir of large capacity inside the sarcoplasmic reticulum (SR), presumably the protein calsequestrin. The buffering power of calsequestrin in vitro has a paradoxical dependence on [Ca(2+)] that should be valuable for function. Here, we demonstrate that this dependence is present in living cells. Ca(2+) signals elicited by membrane depolarization under voltage clamp were compared in single skeletal fibers of wild-type (WT) and double (d) Casq-null mice, which lack both calsequestrin isoforms. In nulls, Ca(2+) release started normally, but the store depleted much more rapidly than in the WT. This deficit was reflected in the evolution of SR evacuability, E, which is directly proportional to SR Ca(2+) permeability and inversely to its Ca(2+) buffering power, B. In WT mice E starts low and increases progressively as the SR is depleted. In dCasq-nulls, E started high and decreased upon Ca(2+) depletion. An elevated E in nulls is consistent with the decrease in B expected upon deletion of calsequestrin. The different value and time course of E in cells without calsequestrin indicate that the normal evolution of E reflects loss of B upon SR Ca(2+) depletion. Decrement of B upon SR depletion was supported further. When SR calcium was reduced by exposure to low extracellular [Ca(2+)], release kinetics in the WT became similar to that in the dCasq-null. E became much higher, similar to that of null cells. These results indicate that calsequestrin not only stores Ca(2+), but also varies its affinity in ways that progressively increase the ability of the store to deliver Ca(2+) as it becomes depleted, a novel feedback mechanism of potentially valuable functional implications. The study revealed a surprisingly modest loss of Ca(2+) storage capacity in null cells, which may reflect concurrent changes, rather than detract from the physiological importance of calsequestrin.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
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Megjelenés:Journal of General Physiology 136 : 3 (2010), p. 325-338. -
További szerzők:Sztretye Mónika (1981-) (élettanász, elektrofiziológus) Manno, Carlo (1978-) (kutató) Pouvreau, Sandrine Zhou, Jingsong (1968-) (kutató) Knollmann, Bjorn C. Protasi, Feliciano Allen, Paul D. (1960-) (kuató) Ríos, Eduardo (1945-) (kutató)
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2.

001-es BibID:BIBFORM035803
Első szerző:Sztretye Mónika (élettanász, elektrofiziológus)
Cím:D4cpv-calsequestrin : a sensitive ratiometric biosensor accurately targeted to the calcium store of skeletal muscle / Sztretye, M., Yi, J., Figueroa, L., Zhou, J., Royer, L., Rios, E.
Dátum:2011
ISSN:0022-1295
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal Of General Physiology. - 138 : 2 (2011), p. 211-229. -
További szerzők:Yi, Jianxun (1970-) (kutató) Figueroa, Lourdes (1978-) (kutató) Zhou, Jingsong (1968-) (kutató) Royer, Leandro (1975-) (kutató) Ríos, Eduardo (1945-) (kutató)
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3.

001-es BibID:BIBFORM031846
035-os BibID:PMID:21788611 WOS:000293122500009
Első szerző:Sztretye Mónika (élettanász, elektrofiziológus)
Cím:Measurement of RyR permeability reveals a role of calsequestrin in termination of SR Ca(2+) release in skeletal muscle / Monika Sztretye, Jianxun Yi, Lourdes Figueroa, Jingsong Zhou, Leandro Royer, Eduardo Ríos
Dátum:2011
ISSN:0022-1295
Megjegyzések:The mechanisms that terminate Ca(2+) release from the sarcoplasmic reticulum are not fully understood. D4cpv-Casq1 (Sztretye et al. 2011. J. Gen. Physiol. doi:10.1085/jgp.201010591) was used in mouse skeletal muscle cells under voltage clamp to measure free Ca(2+) concentration inside the sarcoplasmic reticulum (SR), [Ca(2+)](SR), simultaneously with that in the cytosol, [Ca(2+)](c), during the response to long-lasting depolarization of the plasma membrane. The ratio of Ca(2+) release flux (derived from [Ca(2+)](c)(t)) over the gradient that drives it (essentially equal to [Ca(2+)](SR)) provided directly, for the first time, a dynamic measure of the permeability to Ca(2+) of the releasing SR membrane. During maximal depolarization, flux rapidly rises to a peak and then decays. Before 0.5 s, [Ca(2+)](SR) stabilized at 35% of its resting level; depletion was therefore incomplete. By 0.4 s of depolarization, the measured permeability decayed to 10% of maximum, indicating ryanodine receptor channel closure. Inactivation of the t tubule voltage sensor was immeasurably small by this time and thus not a significant factor in channel closure. In cells of mice null for Casq1, permeability did not decrease in the same way, indicating that calsequestrin (Casq) is essential in the mechanism of channel closure and termination of Ca(2+) release. The absence of this mechanism explains why the total amount of calcium releasable by depolarization is not greatly reduced in Casq-null muscle (Royer et al. 2010. J. Gen. Physiol. doi:10.1085/jgp.201010454). When the fast buffer BAPTA was introduced in the cytosol, release flux became more intense, and the SR emptied earlier. The consequent reduction in permeability accelerated as well, reaching comparable decay at earlier times but comparable levels of depletion. This observation indicates that [Ca(2+)](SR), sensed by Casq and transmitted to the channels presumably via connecting proteins, is determinant to cause the closure that terminates Ca(2+) release.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Journal of General Physiology. - 138 : 2 (2011), p. 231-247. -
További szerzők:Yi, Jianxun (1970-) (kutató) Figueroa, Lourdes (1978-) (kutató) Zhou, Jingsong (1968-) (kutató) Royer, Leandro (1975-) (kutató) Ríos, Eduardo (1945-) (kutató)
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