Characterization of 5′-regulatory region of human myostatin gene:: regulation by dexamethasone in vitro
Characterization of 5′-regulatory region of human myostatin gene:: regulation by dexamethasone in vitro
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DOI：
10.1152/ajpendo.2001.281.6.e1128
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发表时间：
2001-12-01
影响因子：
5.1
通讯作者：
Bhasin, S
中科院分区：
文献类型：
--
作者：
Ma, K;Mallidis, C;Bhasin, S
我们克隆并鉴定了一个3.3kb的片段，该片段含有人肌肉生长抑制素基因的5 '调控区。该启动子序列包含糖皮质激素、雄激素、甲状腺激素、生肌分化因子1、肌细胞增强因子2、过氧化物酶体增殖物激活受体和核因子-κ B的推定肌肉生长反应元件。为了鉴定肌生长抑制素基因转录和调控的重要位点，将8个缺失构建体置于C2 C12和L 6骨骼肌细胞中。与成肌细胞相比，在肌管中发现构建体的转录活性显著更高。为了研究糖皮质激素是否调节肌肉生长抑制素基因表达，我们将两种细胞系与地塞米松一起孵育。在这两种情况下，地塞米松剂量依赖性地增加启动子的转录活性和内源性肌肉生长抑制素的表达。当细胞与糖皮质激素受体拮抗剂RU-486共孵育时，地塞米松的作用被阻断。这些结果表明，糖皮质激素上调肌肉生长抑制素的表达诱导基因转录，可能通过糖皮质激素受体介导的途径。我们推测糖皮质激素相关的肌肉萎缩可能部分是由于肌肉生长抑制素表达的上调。
We cloned and characterized a 3.3-kb fragment containing the 5'-regulatory region of the human myostatin gene. The promoter sequence contains putative muscle growth response elements for glucocorticoid, androgen, thyroid hormone, myogenic differentiation factor 1, myocyte enhancer factor 2, peroxisome proliferator-activated receptor, and nuclear factor-kappaB. To identify sites important for myostatin's gene transcription and regulation, eight deletion constructs were placed in C2C12 and L6 skeletal muscle cells. Transcriptional activity of the constructs was found to be significantly higher in myotubes compared with that of myoblasts. To investigate whether glucocorticoids regulate myostatin gene expression, we incubated both cell lines with dexamethasone. On both occasions, dexamethasone dose dependently increased both the promoter's transcriptional activity and the endogenous myostatin expression. The effects of dexamethasone were blocked when the cells were coincubated with the glucocorticoid receptor antagonist RU-486. These findings suggest that glucocorticoids upregulate myostatin expression by inducing gene transcription, possibly through a glucocorticoid receptor-mediated pathway. We speculate that glucocorticoid-associated muscle atrophy might be due in part to the upregulation of myostatin expression.