LeClair Renée J, Durmus Tahir, Wang Qiaozeng, Pyagay Peter, Terzic Aleksandra, Lindner Volkhard
Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME 04074, USA.
Circ Res. 2007 Mar 30;100(6):826-33. doi: 10.1161/01.RES.0000260806.99307.72. Epub 2007 Feb 22.
We identified collagen triple helix repeat containing-1 (Cthrc1) as a novel gene expressed in the adventitia and neointima on arterial injury and found that it functionally increases cell migration while reducing collagen deposition. To address the in vivo role of Cthrc1, we generated transgenic mouse lines that constitutively overexpress Cthrc1. An intercross of 2 transgenic lines produced offspring with brittle bones caused by a reduction in collagenous bone matrix. Hemizygous Cthrc1 transgenic mice developed normally but neointimal lesion formation and adventitial collagen deposition in response to carotid artery ligation were significantly reduced compared with wild-type littermates. In 75% of Cthrc1 transgenic mice, cartilaginous metaplasia of medial smooth muscle cells was observed as assessed by Alcian blue staining and expression of the chondrocyte marker collagen type II. Transforming growth factor-beta signaling was reduced in smooth muscle cells of Cthrc1 transgenic arteries, as demonstrated by reduced phospho-Smad2/3 immunoreactivity, whereas Smad signaling related to bone morphogenetic proteins was unaffected. Similarly, primary smooth muscle cells and PAC1 smooth muscle cells overexpressing Cthrc1 had reduced levels of phospho-Smad2/3 as well as procollagen. Furthermore, Cthrc1 inhibited transforming growth factor-beta-sensitive reporter constructs in smooth muscle but not endothelial cells. These data indicate that Cthrc1 is a cell-type-specific inhibitor of transforming growth factor-beta, which in turn impacts collagen type I and III deposition, neointimal formation, and dedifferentiation of smooth muscle cells.
我们鉴定出含胶原蛋白三螺旋重复序列-1（Cthrc1）是一种在动脉损伤时在外膜和新生内膜中表达的新基因，并发现它在功能上增加细胞迁移，同时减少胶原蛋白沉积。为了研究Cthrc1在体内的作用，我们构建了组成型过表达Cthrc1的转基因小鼠品系。两个转基因品系杂交产生的后代出现了由于胶原骨基质减少导致的骨骼脆弱。半合子Cthrc1转基因小鼠发育正常，但与野生型同窝小鼠相比，对颈动脉结扎的反应中新生内膜病变形成和外膜胶原蛋白沉积明显减少。通过阿尔新蓝染色和软骨细胞标志物II型胶原蛋白的表达评估，在75%的Cthrc1转基因小鼠中观察到中膜平滑肌细胞的软骨化生。Cthrc1转基因动脉的平滑肌细胞中转化生长因子-β信号传导减少，表现为磷酸化Smad2/3免疫反应性降低，而与骨形态发生蛋白相关的Smad信号传导未受影响。同样，过表达Cthrc1的原代平滑肌细胞和PAC1平滑肌细胞中磷酸化Smad2/3以及前胶原水平降低。此外，Cthrc1抑制平滑肌细胞而非内皮细胞中的转化生长因子-β敏感报告基因构建体。这些数据表明，Cthrc1是转化生长因子-β的细胞类型特异性抑制剂，进而影响I型和III型胶原蛋白沉积、新生内膜形成以及平滑肌细胞的去分化。
