Unique and redundant roles of Smad3 in TGF-β-mediated regulation of long bone development in organ culture
Unique and redundant roles of Smad3 in TGF-β-mediated regulation of long bone development in organ culture
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DOI：
10.1002/dvdy.20100
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发表时间：
2004-08-01
影响因子：
2.5
通讯作者：
Serra, R
中科院分区：
文献类型：
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作者：
Alvarez, J;Serra, R
转化生长因子-β(转化生长因子-β)最典型的细胞内信号分子是Smads。R-Smad与转化生长因子-βI型受体相互作用，并被其直接磷酸化。然后，磷酸化的R-Smads可以与Smad4结合，转移到细胞核并调节转录。特定的R-SMAD为转化生长因子-β超家族成员传递不同的信号。Smad2和-3通过转化生长因子-β/激活素介导信号转导，而Smad1、-5和-8介导骨形态发生蛋白信号转导。转化生长因子-β通过软骨膜依赖的机制抑制培养的跖骨器官的增殖和肥大分化。为了确定转化生长因子-β信号在软骨膜中的作用机制，我们验证了转化生长因子-β限制性的Smad2和Smad3在胚胎跖骨器官培养中调控软骨细胞增殖和分化的假说。用含有显性-阴性Smad2(Ad-Smad2-3SA)和Smad3(Ad-Smad3DeltaC)的腺病毒感染软骨膜。观察转化生长因子-β1对细胞增殖和分化的影响。将结果与感染β-半乳糖苷酶报告病毒(Ad-β-GAL)的对照骨进行比较。Ad-Smad2-3SA完全阻断了转化生长因子-β1对足底发育的影响，而Ad-Smad3-DeltaC仅部分阻断了转化生长因子-β1的作用。为了进一步研究Smad3在长骨发育中的作用，比较了Smad3(+/+)和Smad3(EX8/EX8)小鼠培养上清中转化生长因子-β1的反应性。Smad3的缺失仅部分阻断了转化生长因子-β1对分化的影响。相反，转化生长因子-β1对软骨细胞增殖的影响被完全阻断。我们的结论是，软骨膜中的Smad2信号可以补偿Smad3的缺失，从而调节肥大分化的抑制；然而，Smad3是转化生长因子-β1介导的增殖效应所必需的。(C)2004年Wiley-Liss公司
The most well-characterized intracellular signaling molecules for transforming growth factor-beta (TGF-beta) are the Smads. R-Smads interact with and are phosphorylated directly by the TGF-beta type I receptor. Phosphorylated R-Smads can then associate with Smad4, translocate to the nucleus and regulate transcription. Specific R-Smads transduce distinct signals for members of the TGF-beta superfamily. Smad2 and -3 mediate signaling by TGF-beta/activin, whereas Smad1, -5, and -8 mediate bone morphogenetic protein signaling. TGF-beta inhibits proliferation and hypertrophic differentiation in metatarsal organ cultures by a perichondrium-dependent mechanism. To determine the mechanism of TGF-beta signaling in the perichondrium, we tested the hypothesis that TGF-beta-restricted Smad2 and Smad3 regulate chondrocyte proliferation and differentiation in embryonic metatarsal organ cultures. Perichondrium was infected with adenoviruses containing dominant-negative forms of Smad2 (Ad-Smad2-3SA) and Smad3 (Ad-Smad3DeltaC). Proliferation and differentiation were measured in response to treatment with TGF-beta1. Results were compared with control bones infected with a beta-galactosidase reporter virus (Ad-beta-gal). Infection with Ad-Smad2-3SA completely blocked the effects of TGF-beta1 on metatarsal development while Ad-Smad3DeltaC only partially blocked TGF-beta1 effects. To further characterize the role of Smad3 in long bone development, TGF-beta1 responsiveness in cultures from Smad3(+/+) and Smad3(ex8/ex8) mice were compared. Loss of Smad3 only partially blocked the effects of TGF-beta1 on differentiation. In contrast, the effects of TGF-beta1 on chondrocyte proliferation were blocked completely. We conclude that Smad2 signaling in the perichondrium can compensate for the loss of Smad3 to regulate inhibition of hypertrophic differentiation; however, Smad3 is required for TGF-beta1-mediated effects on proliferation. (C) 2004 Wiley-Liss, Inc.