TY - JOUR
T1 - Conformation of ryanodine receptor-2 gates store-operated calcium entry in rat pulmonary arterial myocytes
AU - Lin, Amanda H.Y.
AU - Sun, Hui
AU - Paudel, Omkar
AU - Lin, Mo Jun
AU - Sham, James S.K.
N1 - Funding Information:
This work was supported, in whole or in part, by the National Institutes of Health grants (R01 HL-075134 and HL-071835), and American Heart Association Grant-in-Aid to J.S.K.S.; and American Lung Association Senior Research Training Fellowship to A.H.Y.L.
Publisher Copyright:
© 2016 The Author.
PY - 2016/7/1
Y1 - 2016/7/1
N2 - Aims: Store-operated Ca2+ entry (SOCE) contributes to a multitude of physiological and pathophysiological functions in pulmonary vasculatures. SOCE attributable to inositol 1,4,5-trisphosphate receptor (InsP3R)-gated Ca2+ store has been studied extensively, but the role of ryanodine receptor (RyR)-gated store in SOCE remains unclear. The present study aims to delineate the relationship between RyR-gated Ca2+ stores and SOCE, and characterize the properties of RyR-gated Ca2+ entry in pulmonary artery smooth muscle cells (PASMCs). Methods and results: PASMCs were isolated from intralobar pulmonary arteries of male Wister rats. Application of the RyR1/2 agonist 4-chloro-m-cresol (4-CmC) activated robust Ca2+ entry in PASMCs. It was blocked by Gd3+ and the RyR2 modulator K201 but was unaffected by the RyR1/3 antagonist dantrolene and the InsP3R inhibitor xestospongin C, suggesting RyR2 is mainly involved in the process. siRNA knockdown of STIM1, TRPC1, and Orai1, or interruption of STIM1 translocation with ML-9 significantly attenuated the 4-CmC-induced SOCE, similar to SOCE induced by thapsigargin. However, depletion of RyR-gated store with caffeine failed to activate Ca2+ entry. Inclusion of ryanodine, which itself did not cause Ca2+ entry, uncovered caffeine-induced SOCE in a concentration-dependent manner, suggesting binding of ryanodine to RyR is permissive for the process. This Ca2+ entry had the same molecular and pharmacological properties of 4-CmC-induced SOCE, and it persisted once activated even after caffeine washout. Measurement of Ca2+ in sarcoplasmic reticulum (SR) showed that 4-CmC and caffeine application with or without ryanodine reduced SR Ca2+ to similar extent, suggesting store-depletion was not the cause of the discrepancy. Moreover, caffeine/ryanodine and 4-CmC failed to initiate SOCE in cells transfected with the ryanodine-binding deficient mutant RyR2-I4827T. Conclusions: RyR2-gated Ca2+ store contributes to SOCE in PASMCs; however, store-depletion alone is insufficient but requires a specific RyR conformation modifiable by ryanodine binding to activate Ca2+ entry.
AB - Aims: Store-operated Ca2+ entry (SOCE) contributes to a multitude of physiological and pathophysiological functions in pulmonary vasculatures. SOCE attributable to inositol 1,4,5-trisphosphate receptor (InsP3R)-gated Ca2+ store has been studied extensively, but the role of ryanodine receptor (RyR)-gated store in SOCE remains unclear. The present study aims to delineate the relationship between RyR-gated Ca2+ stores and SOCE, and characterize the properties of RyR-gated Ca2+ entry in pulmonary artery smooth muscle cells (PASMCs). Methods and results: PASMCs were isolated from intralobar pulmonary arteries of male Wister rats. Application of the RyR1/2 agonist 4-chloro-m-cresol (4-CmC) activated robust Ca2+ entry in PASMCs. It was blocked by Gd3+ and the RyR2 modulator K201 but was unaffected by the RyR1/3 antagonist dantrolene and the InsP3R inhibitor xestospongin C, suggesting RyR2 is mainly involved in the process. siRNA knockdown of STIM1, TRPC1, and Orai1, or interruption of STIM1 translocation with ML-9 significantly attenuated the 4-CmC-induced SOCE, similar to SOCE induced by thapsigargin. However, depletion of RyR-gated store with caffeine failed to activate Ca2+ entry. Inclusion of ryanodine, which itself did not cause Ca2+ entry, uncovered caffeine-induced SOCE in a concentration-dependent manner, suggesting binding of ryanodine to RyR is permissive for the process. This Ca2+ entry had the same molecular and pharmacological properties of 4-CmC-induced SOCE, and it persisted once activated even after caffeine washout. Measurement of Ca2+ in sarcoplasmic reticulum (SR) showed that 4-CmC and caffeine application with or without ryanodine reduced SR Ca2+ to similar extent, suggesting store-depletion was not the cause of the discrepancy. Moreover, caffeine/ryanodine and 4-CmC failed to initiate SOCE in cells transfected with the ryanodine-binding deficient mutant RyR2-I4827T. Conclusions: RyR2-gated Ca2+ store contributes to SOCE in PASMCs; however, store-depletion alone is insufficient but requires a specific RyR conformation modifiable by ryanodine binding to activate Ca2+ entry.
KW - Canonical transient receptor potential 1 (TRPC1)
KW - Pulmonary arterial smooth muscle cells
KW - Ryanodine receptor (RyR)
KW - Store-operated Ca entry (SOCE)
KW - Stromal interaction molecule 1 (STIM1)
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U2 - 10.1093/cvr/cvw067
DO - 10.1093/cvr/cvw067
M3 - Article
C2 - 27013634
AN - SCOPUS:85007040174
SN - 0008-6363
VL - 111
SP - 94
EP - 104
JO - Cardiovascular research
JF - Cardiovascular research
IS - 1
ER -