Cytosolic calcium transients are a determinant of contraction-induced HSP72 transcription in single skeletal muscle fibers.
Cytosolic calcium transients are a determinant of contraction-induced HSP72 transcription in single skeletal muscle fibers.
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胞质钙瞬变是单个骨骼肌纤维中收缩诱导的 HSP72 转录的决定因素。
DOI：
10.1152/japplphysiol.01060.2015
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Hogan,MichaelC
中科院分区：
文献类型：
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作者：
Stary,CreedM;Hogan,MichaelC
运动后诱导骨骼肌热休克蛋白72（HSP 72）转录的内在激活因子尚不清楚。我们假设，胞质Ca 2+瞬变发生的去极化是一个决定因素。我们利用完整的，单一的骨骼肌纤维从非洲爪蟾测试的作用，胞质Ca 2+瞬态和其他几个运动相关的因素（疲劳，缺氧，AMP激酶，和跨桥循环）对HSP 72转录的激活。HSP 72和HSP 60 mRNA水平用实时定量PCR评估;胞浆Ca 2+浓度（[Ca 2 +]cyt）用fura-2评估。疲劳和非疲劳收缩均导致HSP 72 mRNA的显著增加。正如所料，峰值[Ca ~（2+）]cytremained紧密耦合峰在收缩的纤维张力。用N-苄基-对甲苯磺酰胺（BTS）预处理后，细胞内[Ca ~（2+）]_c峰与对照组相比无明显变化，但峰电位降低。尽管兴奋-收缩解偶联，BTS处理的纤维表现出显着增加HSP 72 mRNA。缺氧（Po_2 <3 mmHg）或AMP激酶激活对HSP 72 mRNA水平无影响。这些结果表明，间歇性的细胞内钙瞬变发生骨骼肌去极化提供了足够的激活刺激HSP 72转录。与疲劳发展和跨桥自行车相关的代谢或机械因素可能发挥更有限的作用。
The intrinsic activating factors that induce transcription of heat shock protein 72 (HSP72) in skeletal muscle following exercise remain unclear. We hypothesized that the cytosolic Ca2+transient that occurs with depolarization is a determinant. We utilized intact, single skeletal muscle fibers fromXenopus laevisto test the role of the cytosolic Ca2+transient and several other exercise-related factors (fatigue, hypoxia, AMP kinase, and cross-bridge cycling) on the activation of HSP72 transcription. HSP72 and HSP60 mRNA levels were assessed with real-time quantitative PCR; cytosolic Ca2+concentration ([Ca2+]cyt) was assessed with fura-2. Both fatiguing and nonfatiguing contractions resulted in a significant increase in HSP72 mRNA. As expected, peak [Ca2+]cytremained tightly coupled with peak developed tension in contracting fibers. Pretreatment withN-benzyl-p-toluene sulfonamide (BTS) resulted in depressed peak developed tension with stimulation, while peak [Ca2+]cytremained largely unchanged from control values. Despite excitation-contraction uncoupling, BTS-treated fibers displayed a significant increase in HSP72 mRNA. Treatment of fibers with hypoxia (Po2: <3 mmHg) or AMP kinase activation had no effect on HSP72 mRNA levels. These results suggest that the intermittent cytosolic Ca2+transient that occurs with skeletal muscle depolarization provides a sufficient activating stimulus for HSP72 transcription. Metabolic or mechanical factors associated with fatigue development and cross-bridge cycling likely play a more limited role.