Abstract
In the absence of store depletion, plasmalemmal Ca2+ permeability in resting muscle is very low, and its contribution in the maintenance of Ca2+ homeostasis at rest has not been studied in detail. Junctophilin 1 knock-out myotubes (JP1 KO) have a severe reduction in store-operated Ca2+ entry, presumably caused by physical alteration of the sarcoplasmic reticulum (SR) and T-tubule junction, leading to disruption of the SR signal sent by Stim1 to activate Orai1. Using JP1 KO myotubes as a model, we assessed the contribution of the Orai1-mediated Ca2+ entry pathway on overall Ca2+ homeostasis at rest with no store depletion. JP1 KO myotubes have decreased Ca2+ entry, [Ca2+] rest, and intracellular Ca2+ content compared with WT myotubes and unlike WT myotubes, are refractory to BTP2, a Ca2+ entry blocker. JP1 KO myotubes show down-regulation of Orai1 and Stim1 proteins, suggesting that this pathway may be important in the control of resting Ca 2+ homeostasis. WT myotubes stably transduced with Orai1(E190Q) had similar alterations in their resting Ca2+ homeostasis as JP1 KO myotubes and were also unresponsive to BTP2. JP1 KO cells show decreased expression of TRPC1 and -3 but overexpress TRPC4 and -6; on the other hand, the TRPC expression profile in Orai1(E190Q) myotubes was comparable with WT. These data suggest that an important fraction of resting plasmalemmal Ca2+ permeability is mediated by the Orai1 pathway, which contributes to the control of [Ca2+]rest and resting Ca2+ stores and that this pathway is defective in JP1 KO myotubes.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 39171-39179 |
| Number of pages | 9 |
| Journal | Journal of Biological Chemistry |
| Volume | 285 |
| Issue number | 50 |
| DOIs | |
| State | Published - Dec 10 2010 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Biochemistry
- Cell Biology
- Molecular Biology
Cite this
Impaired Orai1-mediated resting Ca2+ entry reduces the cytosolic [Ca2+] and sarcoplasmic reticulum Ca2+ loading in quiescent junctophilin 1 knock-out myotubes. / Li, Hongli; Ding, Xudong; Lopez, Jose R.; Takeshima, Hiroshi; Ma, Jianjie; Allen, Paul D.; Eltit, Jose M.
In: Journal of Biological Chemistry, Vol. 285, No. 50, 10.12.2010, p. 39171-39179.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Impaired Orai1-mediated resting Ca2+ entry reduces the cytosolic [Ca2+] and sarcoplasmic reticulum Ca2+ loading in quiescent junctophilin 1 knock-out myotubes
AU - Li, Hongli
AU - Ding, Xudong
AU - Lopez, Jose R.
AU - Takeshima, Hiroshi
AU - Ma, Jianjie
AU - Allen, Paul D.
AU - Eltit, Jose M.
PY - 2010/12/10
Y1 - 2010/12/10
N2 - In the absence of store depletion, plasmalemmal Ca2+ permeability in resting muscle is very low, and its contribution in the maintenance of Ca2+ homeostasis at rest has not been studied in detail. Junctophilin 1 knock-out myotubes (JP1 KO) have a severe reduction in store-operated Ca2+ entry, presumably caused by physical alteration of the sarcoplasmic reticulum (SR) and T-tubule junction, leading to disruption of the SR signal sent by Stim1 to activate Orai1. Using JP1 KO myotubes as a model, we assessed the contribution of the Orai1-mediated Ca2+ entry pathway on overall Ca2+ homeostasis at rest with no store depletion. JP1 KO myotubes have decreased Ca2+ entry, [Ca2+] rest, and intracellular Ca2+ content compared with WT myotubes and unlike WT myotubes, are refractory to BTP2, a Ca2+ entry blocker. JP1 KO myotubes show down-regulation of Orai1 and Stim1 proteins, suggesting that this pathway may be important in the control of resting Ca 2+ homeostasis. WT myotubes stably transduced with Orai1(E190Q) had similar alterations in their resting Ca2+ homeostasis as JP1 KO myotubes and were also unresponsive to BTP2. JP1 KO cells show decreased expression of TRPC1 and -3 but overexpress TRPC4 and -6; on the other hand, the TRPC expression profile in Orai1(E190Q) myotubes was comparable with WT. These data suggest that an important fraction of resting plasmalemmal Ca2+ permeability is mediated by the Orai1 pathway, which contributes to the control of [Ca2+]rest and resting Ca2+ stores and that this pathway is defective in JP1 KO myotubes.
AB - In the absence of store depletion, plasmalemmal Ca2+ permeability in resting muscle is very low, and its contribution in the maintenance of Ca2+ homeostasis at rest has not been studied in detail. Junctophilin 1 knock-out myotubes (JP1 KO) have a severe reduction in store-operated Ca2+ entry, presumably caused by physical alteration of the sarcoplasmic reticulum (SR) and T-tubule junction, leading to disruption of the SR signal sent by Stim1 to activate Orai1. Using JP1 KO myotubes as a model, we assessed the contribution of the Orai1-mediated Ca2+ entry pathway on overall Ca2+ homeostasis at rest with no store depletion. JP1 KO myotubes have decreased Ca2+ entry, [Ca2+] rest, and intracellular Ca2+ content compared with WT myotubes and unlike WT myotubes, are refractory to BTP2, a Ca2+ entry blocker. JP1 KO myotubes show down-regulation of Orai1 and Stim1 proteins, suggesting that this pathway may be important in the control of resting Ca 2+ homeostasis. WT myotubes stably transduced with Orai1(E190Q) had similar alterations in their resting Ca2+ homeostasis as JP1 KO myotubes and were also unresponsive to BTP2. JP1 KO cells show decreased expression of TRPC1 and -3 but overexpress TRPC4 and -6; on the other hand, the TRPC expression profile in Orai1(E190Q) myotubes was comparable with WT. These data suggest that an important fraction of resting plasmalemmal Ca2+ permeability is mediated by the Orai1 pathway, which contributes to the control of [Ca2+]rest and resting Ca2+ stores and that this pathway is defective in JP1 KO myotubes.
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UR - http://www.scopus.com/inward/citedby.url?scp=78649847421&partnerID=8YFLogxK
U2 - 10.1074/jbc.M110.149690
DO - 10.1074/jbc.M110.149690
M3 - Article
C2 - 20937810
AN - SCOPUS:78649847421
VL - 285
SP - 39171
EP - 39179
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 50
ER -