Reduced osteoblast activity in the mice lacking TR4 nuclear receptor leads to osteoporosis.
Reduced osteoblast activity in the mice lacking TR4 nuclear receptor leads to osteoporosis.
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DOI：
10.1186/1477-7827-10-43
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发表时间：
2012-06-07
期刊：
影响因子：
--
通讯作者：
Chang C
中科院分区：
文献类型：
--
作者：
Lin SJ;Ho HC;Lee YF;Liu NC;Liu S;Li G;Shyr CR;Chang C
早期研究表明TR4核受体可能在骨骼发育中起重要作用，但其具体机制尚不清楚。我们产生了TR4基因敲除小鼠，并将骨骼发育与其野生型同窝仔进行了比较。原代培养骨髓细胞，碱性磷酸酶和茜素红染色检测骨分化。培养原代颅骨，采用定量PCR检测成骨细胞标志基因。荧光素酶报告基因测定、染色质免疫沉淀（ChIP）测定和电泳迁移率变动测定（EMSA）被执行以证明TR4可以直接调节骨分化标记物骨钙素。我们首先发现缺乏TR4的小鼠可能会患上骨质疏松症。然后我们发现，从TR4基因敲除小鼠骨髓中分离的成骨祖细胞显示成骨细胞分化能力降低和钙化。来自TR4敲除小鼠颅骨的成骨细胞原代培养物也显示出较高的增殖率，表明在TR4缺失后小鼠中成骨细胞分化能力较低。机制解剖发现成骨细胞标志物基因，如ALP，I型胶原α 1，骨钙素，PTH和PTHR的表达显着降低，与TR4野生型小鼠相比，在TR4基因敲除小鼠的成骨细胞。荧光素酶报告基因检测、ChIP检测和EMSA等体外细胞系研究进一步证实了TR4可以直接与骨钙素基因的启动子区结合，并以剂量依赖的方式在转录水平上诱导其基因表达。总之，这些结果表明，TR4可能作为一种新的转录因子发挥作用，发挥病理生理作用，在维持正常的成骨细胞的活性，在骨发育和重建，TR4功能的破坏可能会导致多种骨骼异常。
Early studies suggested that TR4 nuclear receptor might play important roles in the skeletal development, yet its detailed mechanism remains unclear. We generated TR4 knockout mice and compared skeletal development with their wild type littermates. Primary bone marrow cells were cultured and we assayed bone differentiation by alkaline phosphatase and alizarin red staining. Primary calvaria were cultured and osteoblastic marker genes were detected by quantitative PCR. Luciferase reporter assays, chromatin immunoprecipitation (ChIP) assays, and electrophoretic mobility shift assays (EMSA) were performed to demonstrate TR4 can directly regulate bone differentiation marker osteocalcin. We first found mice lacking TR4 might develop osteoporosis. We then found that osteoblast progenitor cells isolated from bone marrow of TR4 knockout mice displayed reduced osteoblast differentiation capacity and calcification. Osteoblast primary cultures from TR4 knockout mice calvaria also showed higher proliferation rates indicating lower osteoblast differentiation ability in mice after loss of TR4. Mechanism dissection found the expression of osteoblast markers genes, such as ALP, type I collagen alpha 1, osteocalcin, PTH, and PTHR was dramatically reduced in osteoblasts from TR4 knockout mice as compared to those from TR4 wild type mice. In vitro cell line studies with luciferase reporter assay, ChIP assay, and EMSA further demonstrated TR4 could bind directly to the promoter region of osteocalcin gene and induce its gene expression at the transcriptional level in a dose dependent manner. Together, these results demonstrate TR4 may function as a novel transcriptional factor to play pathophysiological roles in maintaining normal osteoblast activity during the bone development and remodeling, and disruption of TR4 function may result in multiple skeletal abnormalities.
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DOI：
10.1073/pnas.91.13.6040
发表时间：
1994-06-21
影响因子：
11.1
作者：
CHANG, CS;DASILVA, SL;BURBACH, JPH
通讯作者：
BURBACH, JPH
影响因子：
--
作者：
Chen, Lu-Min;Wang, Ruey-Sheng;Chang, Chawnshang
通讯作者：
Chang, Chawnshang
影响因子：
64.5
作者：
Lee, Na Kyung;Sowa, Hideaki;Karsenty, Gerard
通讯作者：
Karsenty, Gerard
影响因子：
15.9
作者：
Zhang, XP;Schwarz, EM;O'Keefe, RJ
通讯作者：
O'Keefe, RJ
影响因子：
4.8
作者：
Lee, YF;Pan, HJ;Chang, CS
通讯作者：
Chang, CS