Research for the mechanisms of anabolic action of parathyroid hormone(PTH) on bone and interaction between PTH and estrogen in osteoblasts

甲状旁腺激素（PTH）对骨的合成代谢作用机制及成骨细胞中PTH与雌激素相互作用的研究

• 批准号: 14571064
• 负责人: SUGIMOTO Toshitsugu
• 金额: $ 2.24万
• 依托单位: Kobe University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14571064/
• 关键词: Parathyroid hormone; Estrogen; Osteoblast; Bone formation; TGFβ; Smad-3; Apoptosis; Insulin-like growth factor I; Insulin-like growth factor-binding protein-5

Although several studies indicated that parathyroid hormone (PTH) exerted anabolic action on bone and estrogen augmented its anabolic action on bone, their precise mechanisms have been unknown. TGFβ stimulates bone formation in vivo and regulates the transcriptional response of the target genes through the two receptor -regulated Smads, Smad2 and Smad3. Our study revealed that Smad3 was an important molecule for bone formation. Next, we examined the effects of PTH on Smad3 and its physiological significance in osteoblasts. PTH promoted Smad3 mRNA and protein levels though PKA and PKC pathways in mouse osteoblastic MC3T3-E1 cells and rat osteoblastic UMR-106 cells. We, next, examined anti-apoptotic effects of PTH and Smad3. Pretreatment with PTH or overexpression of Smad3 decreased the number of apoptotic cells induced by dexamethasone or etoposide. Moreover, a dominant negative mutant, Smad3deltaC, abrogated PTH-induced anti-apoptotic effects. On the other hand, PTH augmented TGFβ-indu … More ced transcriptional activity of Smad3. Furtheremore, PTH enhanced TGFβ-induced production of type1collagen. These observations indicate that PTH amplified the anabolic effects of TGFβ by accelerating the transcriptional activity of Smad3. We first demonstrated that PTH-Smad3 axis exerts anti-apoptotic effects and reinforces the anabolic action by TGFβ in osteoblasts. There is recent evidence about the importance of Wnt signaling in bone formation and we obtained data about stimulatory effects of PTH and Smad3 overexpression on β-catenin expression in osteoblasats. Hence, PTH-Smad-3 axis would be involved in bone anabolic action of PTH. As for studies about the interaction between PTH and estrogen in osteoblasts, estrogen attenuated PTH-induced inhibition of osteoblast proliferation and PTH stimulated osteoblast function in the presence of estrogen pretreatment in human osteoblastic SaOS-2 cells. And, IGF-I and/or IGF-binding protein-5 were involved in the estrogen-induced modulation of PTH action on osteoblast proliferation and function. Less

虽然已有研究表明甲状旁腺激素(PTH)对骨的合成代谢作用，雌激素对骨的合成代谢作用增强，但其确切的作用机制尚不清楚。转化生长因子β通过Smad2和Smad3两种受体调节的Smad2和Smad3在体内刺激骨形成并调节靶基因的转录反应。我们的研究表明，Smad3是骨形成的重要分子。接下来，我们研究了PTH对Smad3的影响及其在成骨细胞中的生理意义。PTH通过PKA和PKC途径促进小鼠成骨细胞MC3T3-E1和大鼠成骨细胞UMR-106中Smad3基因和蛋白的表达。接下来，我们研究了甲状旁腺素和Smad3的抗细胞凋亡作用。甲状旁腺素或过表达Smad3可减少地塞米松或依托泊苷诱导的细胞凋亡。此外，显性负性突变体Smad3deltaC取消了PTH诱导的抗细胞凋亡作用。另一方面，甲状旁腺激素增加转化生长因子β-INDU…Smad3转录活性增强。此外，甲状旁腺激素还能促进转化生长因子β诱导的I型胶原的产生。这些观察结果表明，甲状旁腺素通过促进Smad3的转录活性而增强了转化生长因子β的合成代谢作用。我们首次证实甲状旁腺激素-Smad3轴在成骨细胞中发挥抗凋亡作用，并增强转化生长因子β的合成代谢作用。最近有证据表明Wnt信号在骨形成中的重要性，我们获得了甲状旁腺激素和Smad3过表达对成骨细胞β-catenin表达的刺激作用的数据。因此，PTH-Smad-3轴可能参与了PTH的骨合成代谢作用。在成骨细胞中甲状旁腺激素与雌激素相互作用的研究中，雌激素减弱了甲状旁腺素对人成骨细胞SAOS-2细胞增殖的抑制作用和雌激素对成骨细胞功能的刺激作用。IGF-I和/或IGF结合蛋白-5参与了雌激素诱导的甲状旁腺素对成骨细胞增殖和功能的调节作用。较少

项目成果

Sowa H: "Activations of ERK1/2 and JNK by TGFβ Negatively Regulate Smad3-induced Alkaline Phosphatase Activity and Mineralization in Mouse Osteoblastic Cells"J Biol Chem. 277. 36027-36031 (2002)

Sowa H：“TGFβ 激活 ERK1/2 和 JNK 负调节小鼠成骨细胞中 Smad3 诱导的碱性磷酸酶活性和矿化”J Biol Chem. 277. 36027-36031 (2002)

Sowa T, Kaji H, Yamaguchi T, Sugimoto T, Chihara K.: "Smad3 promotes alkaline phosphatase activity and mineralization of osteoblastic MC3T3-E1 cells."Bone Miner Res. 17. 1190-1199 (2002)

Sowa T、Kaji H、Yamaguchi T、Sugimoto T、Chihara K.：“Smad3 促进成骨细胞 MC3T3-E1 细胞的碱性磷酸酶活性和矿化。”Bone Miner Res。

Sowa H: "Inactivation of menin, the product of the multiple endocrine neoplasia type1(MEN1) gene, inhibits the commitment of multipotential"J Biol Chem. 278. 21058-21069 (2003)

Sowa H：“多发性内分泌肿瘤 1 型 (MEN1) 基因产物 menin 的失活会抑制多潜能的发挥”J Biol Chem。

Sugimoto T, Kaji H, Nakaoka D, Yamauchi M, Yano S, Sugishita T, Baylink D, Mohan S, Chihara T.: "Effect of low-dose of recombinant human growth hormone on bone metabolism in elderly osteoporotic women."Eur J Endocrinol. 147-3. 339-348 (2002)

Sugimoto T、Kaji H、Nakaoka D、Yamauchi M、Yano S、Sugishita T、Baylink D、Mohan S、Chihara T.：“低剂量重组人生长激素对老年骨质疏松女性骨代谢的影响。”Eur J

Jonsson KB: "Fibroblast growth factor 23 in oncogenic osteomalacia and X-linked hypophosphatemia"N Engl J Med. 348・17. 1656-1663 (2003)

Jonsson KB：“致癌性骨软化症和 X 连锁低磷血症中的成纤维细胞生长因子 23”N Engl J Med 348・17（2003）。