Hypoxia regulates osteoblast gene expression
Hypoxia regulates osteoblast gene expression
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DOI：
10.1006/jsre.2001.6128
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发表时间：
2001-07-01
影响因子：
2.2
通讯作者：
Longaker, MT
中科院分区：
文献类型：
--
作者：
Warren, SM;Steinbrech, DS;Longaker, MT
骨折继发的血管破坏产生损伤的低氧梯度，其中伤口中心的氧张力非常低。在体内，这种低氧微环境刺激来自炎症细胞、成纤维细胞、内皮细胞和成骨细胞的多种细胞因子的表达。为了开始剖析这个复杂的系统，我们在体外检查了缺氧对分离的成骨细胞基因表达的影响。了解该系统中的基因表达可能有助于开发旨在加速骨折修复和减少并发症的靶向治疗方式。使用已建立的体外缺氧模型，我们分析了参与骨基质产生和周转的基因的表达。将新生大鼠颅骨成骨细胞置于低氧条件下（pO(2) = 35-40 mm Hg），于0、3、6、24、48 h收集细胞总RNA，采用Northern分析法分析（1）转化生长因子（TGFs）-β1、-β2、-β3及其I型受体的表达模式； (2) I型和III型胶原蛋白； (3)金属蛋白酶-1的组织抑制剂。我们已经证明，缺氧 3 小时内 TGF-β1 基因表达显着升高。尽管 TGF-β2 和 TGF-β3 表达均不受缺氧影响，但 TGF-β I 型受体在 6 小时内大幅上调。此外，细胞外基质支架分子（胶原蛋白 I 和 III）显着但差异性上调。最后，我们证明细胞外基质周转抑制剂（金属蛋白酶-1 的组织抑制剂）的表达在缺氧时显着降低。这些结果表明缺氧可以通过改变细胞因子、骨特异性细胞外基质分子及其调节因子的表达来影响骨愈合。 (C) 2001 年学术出版社。
Vascular disruption secondary to fracture creates a hypoxic gradient of injury wherein the oxygen tension at the center of the wound is very low, In vivo this hypoxic microenvironment stimulates the expression of a variety of cytokines from inflammatory cells, fibroblasts, endothelial cells, and osteoblasts. In order to begin to dissect this complex system, we have examined the effects of hypoxia on isolated osteoblast gene expression in vitro. Understanding gene expression in this system may facilitate the development of targeted therapeutic modalities designed to accelerate fracture repair and reduce complications. Using an established model of in vitro hypoxia, we have analyzed the expression of genes involved in bone matrix production and turnover. Subconfluent neonatal rat calvarial osteoblasts were exposed to hypoxia (pO(2) = 35-40 mm Hg) and total cellular RNA was collected at 0, 3, 6, 24, and 48 h, Northern analysis was used to analyze the expression patterns of (1) transforming growth factors (TGFs)-beta1, -beta2, and -beta3 and their type I receptor; (2) collagens I and III; and (3) tissue inhibitor of metalloproteinase-l. We have demonstrated a marked elevation of TGF-beta1 gene expression within 3 h of hypoxia. Although neither TGF-beta2 nor TGF-beta3 expression was affected by hypoxia, the TGF-beta type I receptor was substantially upregulated within 6 h, In addition, extracellular matrix scaffolding molecules (collagens I and III) were markedly, but differentially, upregulated. Finally, we have demonstrated that the expression of an inhibitor of extracellular matrix turnover, the tissue inhibitor of metalloproteinase-1, was strikingly decreased in response to hypoxia. These results imply that hypoxia can affect osseous healing by altering the expression of cytokines, bone-specific extracellular matrix molecules, and their regulators. (C) 2001 Academic Press.