Evaluation of VEGF-Mediated signaling in primary human cells reveals a paracrine action for VEGF in osteoblast-mediated crosstalk to endothelial cells
Evaluation of VEGF-Mediated signaling in primary human cells reveals a paracrine action for VEGF in osteoblast-mediated crosstalk to endothelial cells
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DOI：
10.1002/jcp.21234
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发表时间：
2008-02-01
影响因子：
5.6
通讯作者：
Wheeler-Jones, Caroline P. D.
中科院分区：
文献类型：
--
作者：
Clarkin, Claire E.;Emery, Roger J.;Wheeler-Jones, Caroline P. D.
内皮细胞和骨细胞之间的沟通是至关重要的，在骨生长，重塑和修复过程中控制血管供应，但协调这种细胞间串扰的分子机制仍然不明确。我们使用原代人和大鼠长骨来源的成骨细胞样细胞（HOB和LOB）和人脐静脉内皮细胞（HUVEC）来询问血管内皮细胞生长因子（VEGF）在成骨细胞：内皮细胞（OB：EC）通信中的潜在自分泌/旁分泌作用，并检查前列腺素（PG），OB和EC行为的已知调节剂，是否改变VEGF的产生。我们发现，PGI（2）的稳定代谢产物6-keto-PGF（1 α）和PGE（2）诱导HOB而不是EC释放VEGF的浓度依赖性增加。在内皮细胞中，VEGF促进早期ERK 1/2激活，晚期环氧合酶-2（考克斯-2）蛋白诱导，以及6-酮-PGF（1 α）的释放。与此形成鲜明对比的是，在暴露于VEGF的HOB中未观察到这些事件的显著调节，但在VEGF处理后，LOB清楚地表现出COX依赖性前列腺素类释放（比EC低10倍）。VEGFR 2/FIk-1免疫标记和VEGFR酪氨酸激酶抑制剂（TKI）阻断VEGF介导的前列腺素生成支持成骨细胞样细胞对外源性VEGF的低水平反应。HOB碱性磷酸酶（ALP）活性增加后，长期非接触共培养与内皮细胞和暴露的内皮细胞VEGF在这个系统中进一步增加OB样细胞分化和显着增强前列腺素释放。我们的研究证实了旁分泌EC介导的VEGF对OB样细胞行为的影响，并且首次支持前列腺素类可能促进这种单向VEGF驱动的OB：EC通信的模型。这些发现可能提供新的制度，通过控制密切耦合的血管供应调节病理性骨重建异常。
Communication between endothelial and bone cells is crucial for controlling vascular supply during bone growth, remodeling, and repair but the molecular mechanisms coordinating this intercellular crosstalk remain ill-defined. We have used primary human and rat long bone-derived osteoblast-like cells (HOB and LOB) and human umbilical vein endothelial cells (HUVEC) to interrogate the potential autocrine/paracrine role of vascular endothelial cell growth factor (VEGF) in osteoblast:endothelial cell (OB:EC) communication and examined whether Prostaglandins (PG), known modulators of both OB and EC behavior, modify VEGF production. We found that the stable metabolite of PGI(2), 6-keto-PGF(1 alpha), and PGE(2), induced a concentration-dependent increase in VEGF release by HOBs but not ECs. In ECs, VEGF promoted early ERK 1/2 activation, late cyclooxygenase-2 (COX-2) protein induction, and release of 6-keto-PGF(1 alpha),. In marked contrast, no significant modulation of these events was observed in HOBs exposed to VEGF, but LOBs clearly exhibited COX-dependent prostanoid release (10-fold less than EC) following VEGF treatment. A low level of osteoblast-like cell responsiveness to exogenous VEGF was supported by VEGFR2/FIk-1 immunolabelling and by blockade of VEGF-mediated prostanoid generation by a VEGFR tyrosine kinase inhibitor (TKI). HOB alkaline phosphatase (ALP) activity was increased following long-term non-contact co-culture with ECs and exposure of ECs to VEGF in this system further increased OB-like cell differentiation and markedly enhanced prostanoid release. Our studies confirm a paracrine EC-mediated effect of VEGF on OB-like cell behavior and are the first supporting a model in which prostanoids may facilitate this unidirectional VEGF-driven OB:EC communication. These findings may offer novel regimes for modulating pathological bone remodeling anomalies through the control of the closely coupled vascular supply.