Smad2 and 3 mediate transforming growth factor-beta1-induced inhibition of chondrocyte maturation.
Smad2 and 3 mediate transforming growth factor-beta1-induced inhibition of chondrocyte maturation.
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发表时间：
2000
期刊：
影响因子：
4.8
通讯作者：
C. M. Ferguson;E. Schwarz;P. Reynolds;J. Puzas;R. Rosier;R. O’Keefe
中科院分区：
文献类型：
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作者：
C. M. Ferguson;E. Schwarz;P. Reynolds;J. Puzas;R. Rosier;R. O’Keefe
转化生长因子-β（TGF-β）是多种细胞功能的多功能调节剂，包括增殖、分化、基质合成和凋亡。在生长板软骨细胞中，TGF-β减慢成熟速率。由于TGF-β信号传导的当前范例涉及Smad蛋白作为靶基因的下游调节剂，我们已经表征了它们作为TGF-β对软骨细胞成熟作用的介质的作用。Smad 2和3均在TGF-β 1信号转导后易位至细胞核，但在BMP-2信号转导后不易位。使用TGF-β响应性和Smad 3敏感性p3 TP-Lux荧光素酶报告基因的共转染实验表明，野生型Smad 3增强，而显性负性Smad 3抑制TGF-β 1诱导的荧光素酶活性。为了证实Smad 2和3作为TGF-β 1对软骨细胞成熟作用的重要介质的作用，我们在病毒感染的软骨细胞培养物中过表达野生型和显性阴性Smad 2和3。野生型Smad 2和3的过表达增强了TGF-β对软骨细胞成熟的抑制作用，如通过colx和碱性磷酸酶活性所确定的，而显性负性Smad 2和3阻断了这些作用。野生型和显性负性形式的Smad 3有更明显的影响比Smad 2。我们的研究结果将Smad 2和3定义为TGF-β 1信号对软骨细胞成熟的抑制作用的关键介质。
Transforming growth factor-beta (TGF-beta) is a multifunctional regulator of a variety of cellular functions, including proliferation, differentiation, matrix synthesis, and apoptosis. In growth plate chondrocytes, TGF-beta slows the rate of maturation. Because the current paradigm of TGF-beta signaling involves Smad proteins as downstream regulators of target genes, we have characterized their role as mediators of TGF-beta effects on chondrocyte maturation. Both Smad2 and 3 translocated to the nucleus upon TGF-beta1 signaling, but not upon BMP-2 signaling. Cotransfection experiments using the TGF-beta responsive and Smad3 sensitive p3TP-Lux luciferase reporter demonstrated that wild-type Smad3 potentiated, whereas dominant negative Smad3 inhibited TGF-beta1 induced luciferase activity. To confirm the role of Smad2 and 3 as essential mediators of TGF-beta1 effects on chondrocyte maturation, we overexpressed both wild-type and dominant negative Smad2 and 3 in virally infected chondrocyte cultures. Overexpression of both wild-type Smad2 and 3 potentiated the inhibitory effect of TGF-beta on chondrocyte maturation, as determined by colx and alkaline phosphatase activity, whereas dominant negative Smad2 and 3 blocked these effects. Wild-type and dominant negative forms of Smad3 had more pronounced effects than Smad2. Our results define Smad2 and 3 as key mediators of the inhibitory effect of TGF-beta1 signaling on chondrocyte maturation.