Decreased BMP2 signal in GIT1 knockout mice slows bone healing.
Decreased BMP2 signal in GIT1 knockout mice slows bone healing.
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GIT1 敲除小鼠中 BMP2 信号的减少会减缓骨愈合。
DOI：
10.1007/s11010-014-2173-5
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发表时间：
2014-12
影响因子：
4.3
通讯作者：
Berk BC
中科院分区：
文献类型：
--
作者：
Sheu TJ;Zhou W;Fan J;Zhou H;Zuscik MJ;Xie C;Yin G;Berk BC
软骨内成骨是骨折愈合的重要阶段，受多种信号通路的调控。转化生长因子b （TGFb）超家族包括TGFb、骨形态发生蛋白（BMPs）和生长分化因子。TGFbs主要调控软骨形成和软骨内成骨。BMP2表现出不同的功效，从骨骼和骨骼外器官的形成到骨骼的成骨和重塑。g蛋白偶联受体激酶2-相互作用蛋白-1 （GIT1）是成骨细胞中的穿梭蛋白，通过促进骨形成和增加血管内皮生长因子的分泌来促进骨折愈合。我们的研究考察了GIT1是否通过BMP2信号通路和/或TGFb信号通路调节骨折愈合。GIT1敲除（KO）小鼠出现骨折愈合延迟、骨折区软骨细胞堆积、磷酸化Smad1/5/8 （pSmad1/5/8）和Runx2染色强度降低。软骨内矿化减弱，磷酸化Smad2/3 （pSmad2/3）染色强度无明显变化。GIT1 KO小鼠骨髓间充质干细胞经BMP2刺激后，pSmad1/5/8水平下降，pSmad1/5/8转运至细胞核。我们检测到TGFb1刺激后pSmad2/3水平没有明显变化。体外培养的C3H10T1/2细胞报告基因分析数据证实了这些发现。GIT1-siRNA在BMP2刺激后通过pSmad1/5/8抑制细胞核转录，而在TGFb1刺激后通过pSmad2/3抑制细胞核转录无显著影响。我们的研究结果表明，GIT1调节Smad1/5/8磷酸化，并介导BMP2调控Runx2表达，从而影响骨折部位的软骨内成骨。
Endochondral ossification, an important stage of fracture healing, is regulated by a variety of signaling pathways. Transforming growth factor b (TGFb) superfamily plays important roles and comprises TGFbs, bone morphogenetic proteins (BMPs), and growth differentiation factors. TGFbs primarily regulate cartilage formation and endochondral ossification. BMP2 shows diverse efficacy, from the formation of skeleton and extraskeletal organs to the osteogenesis and remodeling of bone. G-protein-coupled receptor kinase 2-interacting protein-1 (GIT1), a shuttle protein in osteoblasts, facilitates fracture healing by promoting bone formation and increasing the secretion of vascular endothelial growth factor. Our study examined whether GIT1 regulates fracture healing through the BMP2 signaling pathway and/or through the TGFb signaling pathway. GIT1 knockout (KO) mice exhibited delayed fracture healing, chondrocyte accumulation in the fracture area, and reduced staining intensity of phosphorylated Smad1/5/8 (pSmad1/5/8) and Runx2. Endochondral mineralization diminished while the staining intensity of phosphorylated Smad2/3 (pSmad2/3) showed no significant change. Bone marrow mesenchymal stem cells extracted from GIT1 KO mice showed a decline of pSmad1/5/8 levels and of pSmad1/5/8 translocated into the cell nucleus after BMP2 stimulus. We detected no significant change in the pSmad2/3 level after TGFb1 stimulus. Data obtained from reporter gene analysis of C3H10T1/2 cells cultured in vitro confirmed these findings. GIT1-siRNA inhibited transcription in the cell nucleus via pSmad1/5/8 after BMP2 stimulus but had no significant effect on transcription via pSmad2/3 after TGFb1 stimulus. Our results indicate that GIT1 regulates Smad1/5/8 phosphorylation and mediates BMP2 regulation of Runx2 expression, thus affecting endochondral ossification at the fracture site.
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DOI：
10.1083/jcb.153.1.35
发表时间：
2001-04-02
期刊：
The Journal of cell biology
影响因子：
--
作者：
Yang X;Chen L;Xu X;Li C;Huang C;Deng CX
通讯作者：
Deng CX
影响因子：
5.3
作者：
Yin, GY;Haendeler, J;Berk, BC
通讯作者：
Berk, BC
影响因子：
2.5
作者：
Alvarez, J;Horton, J;Serra, R
通讯作者：
Serra, R
影响因子：
4.8
作者：
Hassan, Mohammad Q.;Tare, Rahul S.;Lian, Jane B.
通讯作者：
Lian, Jane B.
影响因子：
5.6
作者：
Menon, Prashanthi;Yin, Guoyong;Smolock, Elaine M.;Zuscik, Michael J.;Yan, Chen;Berk, Bradford C.
通讯作者：
Berk, Bradford C.