Regulation of sarcoplasmic reticulum calcium pump gene expression by hindlimb unweighting.
Regulation of sarcoplasmic reticulum calcium pump gene expression by hindlimb unweighting.
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DOI：
10.1152/ajpcell.1993.264.5.c1308
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发表时间：
1993-05
期刊：
影响因子：
--
通讯作者：
L. Schulte;J. Navarro;S. Kandarian
中科院分区：
文献类型：
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作者：
L. Schulte;J. Navarro;S. Kandarian
后肢减重（HU）导致几个肌肉特异性基因的上调，这些基因负责比目鱼肌骨骼肌特性的从慢到快的转变，尽管肌肉严重萎缩。本研究的目的是检测肌浆网Ca（2+）-ATP酶的快、慢亚型在mRNA和蛋白水平上的表达，并将它们与Ca（2+）依赖的ATP酶活性和选择的收缩特性联系起来。测定乙酰胆碱受体（AChR）mRNA水平，以比较失重与去神经信号。尾吊大鼠比目鱼肌在各时间点均出现萎缩，HU后28 d肌肉质量下降52%（P < 0.05）。北方印迹分析显示，在HU的第1、4、7、14和28天，快钙泵mRNA的相对表达分别比对照水平增加0、250、910、1，340和4，050%，而慢钙泵mRNA的变化是可变的和适度的。对于相同的时间点，蛋白质印迹分析表明，快速钙泵蛋白的相对表达增加了30，110，320，280，和300%的控制水平，而慢泵蛋白的表达是不变的，除了在28天的HU减少了75%。比Ca（2+）依赖性ATP酶活性在HU 28天时增加了170%（P < 0.05）。在离体条件下测定14和28天的收缩特性，发现无负荷比目鱼肌的张力达峰时间和半松弛时间缩短（P < 0.05），张力-频率曲线明显移动。（250字处删节）
Hindlimb unweighting (HU) causes upregulation of several muscle-specific genes responsible for the slow-to-fast transition in soleus skeletal muscle properties despite the profound muscle atrophy. The purpose of this study was to examine the expression of the fast and slow isoforms of the sarcoplasmic reticulum Ca(2+)-ATPase at the mRNA and protein level in the soleus muscle over a time course of HU and relate them to Ca(2+)-dependent ATPase activity and selected contractile properties. mRNA levels of the acetylcholine receptor (AChR) were measured to compare the signal of unweighting with denervation. Atrophy of the soleus muscles from tail-suspended rats was observed at all time points with muscle mass decreased by 52% at 28 days of HU (P < 0.05). Northern blot analysis showed the relative expression of the fast Ca2+ pump mRNA increased by 0, 250, 910, 1,340, and 4,050% over control levels at 1, 4, 7, 14, and 28 days of HU, respectively, whereas changes in slow mRNA were variable and modest in comparison. For the same time points, Western blot analysis showed relative expression of the fast Ca2+ pump protein increased by 30, 110, 320, 280, and 300% over control levels, whereas the slow-pump protein expression was unchanged except for a 75% decrease at 28 days of HU. Specific Ca(2+)-dependent ATPase activity was increased (P < 0.05) by 170% at 28 days of HU. Contractile properties measured in vitro at 14 and 28 days revealed time to peak tension and one-half relaxation time were shortened (P < 0.05) and a rightward shift in the tension-frequency curves in unloaded soleus muscles.(ABSTRACT TRUNCATED AT 250 WORDS)