Elevated extracellular calcium increases fibroblast growth factor-2 gene and protein expression levels via a cAMP/PKA dependent pathway in cementoblasts
Elevated extracellular calcium increases fibroblast growth factor-2 gene and protein expression levels via a cAMP/PKA dependent pathway in cementoblasts
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DOI：
10.1016/j.bone.2010.05.042
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发表时间：
2010-09-01
期刊：
影响因子：
4.1
通讯作者：
Shimauchi, Hidetoshi
中科院分区：
文献类型：
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作者：
Kanaya, Sousuke;Nemoto, Eiji;Shimauchi, Hidetoshi
成牙骨质细胞，牙根衬里细胞，负责在牙根表面沉积牙骨质，这是建立功能性牙周膜不可或缺的过程。成牙骨质细胞与成骨细胞具有相同的表型特征。细胞外Ca 2+水平升高通过刺激成骨细胞的增殖和分化而与骨生成有关;然而，细胞外Ca 2+信号传导在牙骨质生成中的作用尚未研究。RT-PCR结果显示，细胞外Ca ~（2+）浓度升高可促进成纤维细胞生长因子（FGF）-2基因的表达，其表达高峰出现在6 h。用蛋白激酶A（PKA）抑制剂H89或腺苷酸环化酶抑制剂MDL-12，330 A预处理抑制Ca 2+刺激的Fgf-2表达。相反，用蛋白激酶C（PKC）抑制剂GF-109203 X或磷脂酶C（PLC）抑制剂U 73122预处理不影响Fgf-2转录物的表达，表明Fgf-2表达的增加依赖于PKA而不是PLC/PKC信号通路。用腺苷酸环化酶的激活剂，毛喉素，或cAMP的细胞可渗透类似物，8-Br-cAMP，处理增强了Ca 2+刺激的FGF-2表达，但用毛喉素或8-Br-cAMP的单次处理没有，这表明cAMP的产生是必不可少的，但不足以用于Ca 2+刺激的FGF-2表达。接下来，我们检查了推定受体的阳离子特异性，并表明用三价/二价无机离子Ca 2+、Gd 3+、Sr 2+或Al 3+处理，以cAMP依赖的方式引起Fgf-2 mRNA水平的剂量依赖性增加，而Mg 2+和有机离子新霉素和精胺对Fgf-2基因表达水平没有影响。这些发现表明，细胞外Ca 2+感应机制存在于成牙骨质细胞和其激活导致FGF-2的刺激在cAMP/PKA依赖的方式。了解调控参与调节口腔组织再生的关键基因的途径将有助于基于可靠的生物学原理设计再生疗法。(C)2010年爱思唯尔公司All rights reserved.
Cementoblasts, tooth root lining cells, are responsible for laying down cementum on the root surface, a process that is indispensable for establishing a functional periodontal ligament. Cementoblasts share phenotypical features with osteoblasts. Elevated levels of extracellular Ca2+ have been implicated in osteogenesis by stimulating the proliferation and differentiation of osteoblasts; however, the role of extracellular Ca2+ signaling in cementogenesis has not been examined. Using RT-PCR, we found that elevated levels of extracellular Ca2+ increase fibroblast growth factor (FGF)-2 gene expression with a peak at 6 h. Pretreatment with a protein kinase A (PKA) inhibitor, H89, or an adenylate cyclase inhibitor, MDL-12,330A, inhibited Ca2+-stimulated Fgf-2 expression. In contrast, pretreatment with the protein kinase C (PKC) inhibitor GF-109203X or the phospholipase C (PLC) inhibitor U73122 did not affect the expression of Fgf-2 transcripts, suggesting that the increase in Fgf-2 expression was dependent on the PKA but not the PLC/PKC signaling pathway. Treatment with an activator of adenylate cyclase, forskolin, or a cell-permeable analog of cAMP, 8-Br-cAMP, enhanced Ca2+-stimulated Fgf-2 expression, but a single treatment with forskolin or 8-Br-cAMP did not, suggesting that cAMP generation is indispensable but not sufficient for Ca2+-stimulated FGF2 expression. Next, we examined the cation specificity of the putative receptor and showed that treatment with trivalent/divalent inorganic ions, Ca2+, Gd3+, Sr2+, or Al3+, caused a dose-dependent increase in Fgf-2 mRNA levels in a cAMP-dependent fashion, whereas Mg2+ and the organic ions neomycin and spermine had no effect on Fgf-2 gene expression levels. These findings suggest that an extracellular Ca2+-sensing mechanism is present in cementoblasts and its activation leads to FGF-2 stimulation in a cAMP/PKA dependent fashion. Understanding the pathway regulating key genes involved in modulating the regeneration of oral tissues will assist in designing regenerative therapies based on reliable biological principles. (C) 2010 Elsevier Inc. All rights reserved.