PURPOSE: To review the recent developments in the structure and function of Smad proteins. DATA SOURCES: Both Chinese- and English-language literatures were searched using MEDLINE/CD-ROM (1997 - 2000) and the Index of...PURPOSE: To review the recent developments in the structure and function of Smad proteins. DATA SOURCES: Both Chinese- and English-language literatures were searched using MEDLINE/CD-ROM (1997 - 2000) and the Index of Chinese-Language Literature (1997 - 2000). STUDY SELECTION: Data from published articles about TGF-beta signal transduction in recent domestic and foreign literature were selected. DATA EXTRACTION: Data were mainly extracted from 22 articles which are listed in the reference section of this review. RESULTS: Smad proteins mediate signal transduction induced by the TGF-beta superfamily. Based on their structural and functional properties, Smad proteins are divided into three groups. The first group, receptor-regulated Smads (R-Smads), are phosphorylated by activated type I receptors and form heteromeric complexes with the second group of Smads, common mediator Smads (Co-Smads). These Smad complexes translocate into the nucleus to influence gene transcription. Inhibitory Smads (I-Smads) are the third group and these antagonize the activity of R-Smads. In the nucleus, Smads can directly contact Smad-binding elements (SBE) in target gene promoters. Through interaction with different transcription factors, transcriptional co-activators or co-repressors, Smads elicit different effects in various cell types. The aberrance of Smad proteins has been noted in several human disorders such as fibrosis, hypertrophic scarring and cancer. CONCLUSION: The structure of Smads determines their function as transcriptional factors which translocate signals from the cell surface to the nucleus where Smads regulate TGF-beta superfamily-dependent gene expression.展开更多
Sm ad蛋白直接参与转化生长因子 (TGF-β)、骨形态发生蛋白 (BMP)和活化素的信号传导 ,TGF-β和 BMP是调节骨代谢的信息转导是由 Sm ad蛋白家族成员承担的。在已经鉴定的 8种 Sm ads成员中 ,与骨代谢密切相关的是 Sm ad 1、Sm ad 5及 Sm...Sm ad蛋白直接参与转化生长因子 (TGF-β)、骨形态发生蛋白 (BMP)和活化素的信号传导 ,TGF-β和 BMP是调节骨代谢的信息转导是由 Sm ad蛋白家族成员承担的。在已经鉴定的 8种 Sm ads成员中 ,与骨代谢密切相关的是 Sm ad 1、Sm ad 5及 Smad 4。实验证明在成骨细胞系 Sm ad是 BMP信号转导的关键因子 ,对 Smad蛋白家族的了解将有助于对 TGF-β和展开更多
基金supported by a grant from the National Natural Science Foundation of China(No．G1999054204)； the National Prominent Youth Science Foundation of China(No．39525024)．
文摘PURPOSE: To review the recent developments in the structure and function of Smad proteins. DATA SOURCES: Both Chinese- and English-language literatures were searched using MEDLINE/CD-ROM (1997 - 2000) and the Index of Chinese-Language Literature (1997 - 2000). STUDY SELECTION: Data from published articles about TGF-beta signal transduction in recent domestic and foreign literature were selected. DATA EXTRACTION: Data were mainly extracted from 22 articles which are listed in the reference section of this review. RESULTS: Smad proteins mediate signal transduction induced by the TGF-beta superfamily. Based on their structural and functional properties, Smad proteins are divided into three groups. The first group, receptor-regulated Smads (R-Smads), are phosphorylated by activated type I receptors and form heteromeric complexes with the second group of Smads, common mediator Smads (Co-Smads). These Smad complexes translocate into the nucleus to influence gene transcription. Inhibitory Smads (I-Smads) are the third group and these antagonize the activity of R-Smads. In the nucleus, Smads can directly contact Smad-binding elements (SBE) in target gene promoters. Through interaction with different transcription factors, transcriptional co-activators or co-repressors, Smads elicit different effects in various cell types. The aberrance of Smad proteins has been noted in several human disorders such as fibrosis, hypertrophic scarring and cancer. CONCLUSION: The structure of Smads determines their function as transcriptional factors which translocate signals from the cell surface to the nucleus where Smads regulate TGF-beta superfamily-dependent gene expression.
文摘Sm ad蛋白直接参与转化生长因子 (TGF-β)、骨形态发生蛋白 (BMP)和活化素的信号传导 ,TGF-β和 BMP是调节骨代谢的信息转导是由 Sm ad蛋白家族成员承担的。在已经鉴定的 8种 Sm ads成员中 ,与骨代谢密切相关的是 Sm ad 1、Sm ad 5及 Smad 4。实验证明在成骨细胞系 Sm ad是 BMP信号转导的关键因子 ,对 Smad蛋白家族的了解将有助于对 TGF-β和
