去除后肢神经支配对大鼠骨骼肌中钠钾腺苷酶各亚基表达的影响

Influence of Hindlimb Denervation on Expression of Subunits of Na-K-ATPase in Rat Skeletal Muscle

检测了去除神经支配的大鼠后肢和对侧的对照后肢骨骼肌中钠钾腺苷酶(Na K ATPase)各亚基的蛋白质和mRNA的表达,结果表明,去除后肢神经支配4d,在红色骨骼肌中α2和β1亚基的蛋白质表达显著下降(分别下降了46%和77%),在红色腓肠肌和比目鱼肌中,α2亚基的mRNA水平分别下降了29%和39%,β1亚基的mRNA水平分别下降了80%和52%,在白色骨骼肌中α2亚基的蛋白质和mRNA水平无显著变化;在红色和白色骨骼肌中,α1亚基的蛋白质表达分别增加了20%和15%,同时伴随着更大幅度的mRNA水平的增加,而β2亚基的蛋白质表达未发生显著变化,其mRNA水平在红色腓肠肌中也无显著变化,但在白色腓肠肌中减少了59%.这些结果证实,在去除神经支配的大鼠骨骼肌中,钠钾腺苷酶各亚基的表达受转录和转录后调控,与已报道的胰岛素特异性诱导α2和β1亚基向细胞膜转移的研究结果相吻合.实验中仅α2和β1亚基的蛋白质表达显著下降暗示,在大鼠骨骼肌中,由于去除神经支配造成的胰岛素抵抗使原本受胰岛素调节的钠钾腺苷酶亚基的表达机制受到破坏.

The expression of protein and mRNA of α- and β-subunits of the enzyme was examined in rat skeletal muscle of denervated and contralateral sham hindlimb. 4 days of denervation induced a significant decrease in protein expression of α2-subunit (46%) and β1-subunit (77%) in pooled red muscle. In red gastrocnemius (RG) and soleus, the mRNA level of α2-subunit decreased 29% and 39% respectively, and that of β1-subunit decreased 80% and 52% respectively. However, no significant change in protein and mRNA level of α2-subunit was detected in white pooled muscle. The protein expression of α1-subunit increased 20% and 15% in pooled red and white muscle, respectively, accompanied with a greater increased in mRNA level in RG and white gastrocnemius (WG). There was no significant change in protein expression of β2-subunit in red and white muscle. The mRNA level of β2-subunit in RG did not change significantly, whereas it significantly decreased (59%) in WG. These results suggest that the expression of Na-K-ATPase subunits in denervated rat skeletal muscle is under both transcriptional and post-transcriptional control. Coincident with previous findings showing that insulin specifically induced translocation of α2- and β1-subunit, the markedly decrease in protein expression of α2-and β1-subunit in denervated muscle implies that the expression of Na-K-ATPase subunits normally regulated by insulin become impaired when muscle is made insulin resistance by denervation.