The calcineurin-NFAT pathway and muscle fiber-type gene expression
The calcineurin-NFAT pathway and muscle fiber-type gene expression
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DOI：
10.1152/ajpcell.2000.279.4.c915
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发表时间：
2000-10-01
影响因子：
5.5
通讯作者：
Kandarian, SC
中科院分区：
文献类型：
--
作者：
Swoap, SJ;Hunter, RB;Kandarian, SC
为了测试钙调神经磷酸酶- nfat（活化T细胞的核因子）通路在纤维类型特异性基因表达调控中的作用，在C2C12肌管和存在钙调神经磷酸酶或NFAT2表达质粒的慢速和快速肌肉特异性启动子中检测了钙调神经磷酸酶或NFAT2表达质粒的慢速和快速肌肉。肌管中活性钙调磷酸酶的过度表达可诱导快速和缓慢的肌肉特异性启动子，但不能诱导非肌肉特异性报告子。肌管中NFAT2的过表达并没有激活肌肉特异性启动子，尽管它强烈激活了NFAT报告子。因此，活性钙调磷酸酶的过度表达在体外激活了肌肉特异性启动子的转录，但可能不是通过NFAT2转录因子。同时注射活化的钙调磷酸酶或NFAT2表达质粒后，注射到大鼠浅表鱼肌（慢）和指长伸肌（快）的慢肌球蛋白轻链2 （MLC2）和快肌（内do）质网Ca2+- atp酶（SERCA1）报告基因未被激活。然而，NFAT报告基因在两种肌肉类型中都被NFAT2的过表达强烈激活。钙调磷酸酶和NFAT蛋白的表达以及与NFAT寡核苷酸的结合活性在慢肌和快肌中是不同的。综上所述，这些结果表明，钙调神经磷酸酶和NFAT在成人骨骼肌中诱导和/或维持慢纤维或快纤维类型方面似乎都没有主导作用。此外，不同的途径可能参与肌肉特异性基因在体外和体内的表达。
To test for a role of the calcineurin-NFAT (nuclear factor of activated T cells) pathway in the regulation of fiber type-specific gene expression, slow and fast muscle-specific promoters were examined in C2C12 myotubes and in slow and fast muscle in the presence of calcineurin or NFAT2 expression plasmids. Overexpression of active calcineurin in myotubes induced both fast and slow muscle-specific promoters but not non-muscle-specific reporters. Overexpression of NFAT2 in myotubes did not activate muscle-specific promoters, although it strongly activated an NFAT reporter. Thus overexpression of active calcineurin activates transcription of muscle-specific promoters in vitro but likely not via the NFAT2 transcription factor. Slow myosin light chain 2 (MLC2) and fast sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA1) reporter genes injected into rat soleus (slow) and extensor digitorum longus (EDL) (fast) muscles were not activated by coinjection of activated calcineurin or NFAT2 expression plasmids. However, an NFAT reporter was strongly activated by overexpression of NFAT2 in both muscle types. Calcineurin and NFAT protein expression and binding activity to NFAT oligonucleotides were different in slow vs. fast muscle. Taken together, these results indicate that neither calcineurin nor NFAT appear to have dominant roles in the induction and/or maintenance of slow or fast fiber type in adult skeletal muscle. Furthermore, different pathways may be involved in muscle-specific gene expression in vitro vs. in vivo.