Expression levels of RyR1 and RyR3 control resting free Ca2+ in skeletal muscle
Expression levels of RyR1 and RyR3 control resting free Ca2+ in skeletal muscle
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DOI：
10.1152/ajpcell.00407.2004
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发表时间：
2005-03-01
影响因子：
5.5
通讯作者：
Allen, PD
中科院分区：
文献类型：
--
作者：
Perez, CF;López, JR;Allen, PD
为了更好地了解ryanodine receptor (RyR) type 3 （RyR3）在骨骼肌发育过程中瞬时表达对Ca2+稳态的作用，我们分析了RyR3和RyR1表达水平对培养肌管和肌纤维整体生理的影响。用含有病毒粒子的RyR1或RyR3在0.2、0.4、1.0和4.0感染（MOI）时感染不良肌管，并分析其表达模式、咖啡因敏感性和静息游离Ca2+浓度（[Ca2+](r)）。虽然增加的MOI导致各受体异构体的表达增加，但它对RyRs的免疫模式或calsequestrin、triadin或FKBP-12的表达水平没有显著影响。有趣的是，与表达RyR1的细胞相比，表达RyR3的肌管具有更高的[Ca2+](r)和更低的咖啡因EC50。虽然RyR3对咖啡因的敏感性增加可能归因于表达RyR3的细胞中较高的[Ca2+](r)，但对[H-3] ryanodine结合的研究表明，RyR1和RyR3对咖啡因的敏感性存在内在差异。在出生后发育的不同阶段，胫骨前肌（TA）肌纤维表现出[Ca2+](r)的短暂增加，与其RyR3表达水平相协调。同样，也表达RyR3的成体比目鱼纤维比只表达RyR1的成体TA纤维具有更高的[Ca2+](r)。这些数据表明，在骨骼肌中，RyR3在任何表达水平下都比RyR1增加[Ca2+](r)。这些数据表明，RyR1和RyR3在不同水平上的共表达可能构成了骨骼肌中调节[Ca2+](r)的新机制。
To better understand the role of the transient expression of ryanodine receptor (RyR) type 3 (RyR3) on Ca2+ homeostasis during the development of skeletal muscle, we have analyzed the effect of expression levels of RyR3 and RyR1 on the overall physiology of cultured myotubes and muscle fibers. Dyspedic myotubes were infected with RyR1 or RyR3 containing virions at 0.2, 0.4, 1.0, and 4.0 moieties of infection (MOI), and analysis of their pattern of expression, caffeine sensitivity, and resting free Ca2+ concentration ([Ca2+](r)) was performed. Although increased MOI resulted in increased expression of each receptor isoform, it did not significantly affect the immunopattern of RyRs or the expression levels of calsequestrin, triadin, or FKBP-12. Interestingly, myotubes expressing RyR3 always had significantly higher [Ca2+](r) and lower caffeine EC50 than did cells expressing RyR1. Although some of the increased sensitivity of RyR3 to caffeine could be attributed to the higher [Ca2+](r) in RyR3-expressing cells, studies of [H-3] ryanodine binding demonstrated intrinsic differences in caffeine sensitivity between RyR1 and RyR3. Tibialis anterior ( TA) muscle fibers at different stages of postnatal development exhibited a transient increase in [Ca2+](r) coordinately with their level of RyR3 expression. Similarly, adult soleus fibers, which also express RyR3, had higher [Ca2+](r) than did adult TA fibers, which exclusively express RyR1. These data show that in skeletal muscle, RyR3 increases [Ca2+](r) more than RyR1 does at any expression level. These data suggest that the coexpression of RyR1 and RyR3 at different levels may constitute a novel mechanism by which to regulate [Ca2+](r) in skeletal muscle.