Anabolic effects of PTH in cyclooxygenase-2 knockout osteoblasts in vitro
Anabolic effects of PTH in cyclooxygenase-2 knockout osteoblasts in vitro
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DOI：
10.1016/j.bbrc.2008.05.050
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发表时间：
2008-08-08
影响因子：
3.1
通讯作者：
Pilbeam, Carol
中科院分区：
文献类型：
--
作者：
Choudhary, Shilpa;Huang, Hechang;Pilbeam, Carol
PTH 是体内有效的骨合成代谢剂，但体外合成代谢对成骨细胞分化的影响很难证明。本研究使用 COX-2 敲除 (KO) 和野生型 (WT) 小鼠的骨髓基质细胞 (MSC) 和颅骨成骨细胞 (COB) 培养物，检测了环加氧酶 (COX)-2 和前列腺素 (PG) 的产生在 PTH 对成骨细胞分化的影响中的作用。在整个培养过程中用 PTH (10 nM) 或载体处理细胞。分别在第 14 天和第 21 天测量碱性磷酸酶 (ALP) 和骨钙素 (OCN) mRNA 水平，并在第 21 天测量矿化作用。在磷酸二酯酶抑制剂存在下测量 cAMP 浓度。 PTH 不会刺激 WT 小鼠培养物的分化，但在 KO MSC 培养物中显着增加 ALP 和 OCN mRNA 表达 6 至 7 倍，在 KO COB 培养物中显着增加 2 至 4 倍。 PTH 还增加了 KO MSC 和 COB 培养物中的矿化。在用 COX-2 活性抑制剂 NS-398 处理的 WT MSC 培养物中模拟了对 KO 细胞的影响。 PTH 在 WT 和 KO COB 中类似地增加了 cAMP 浓度。相对于 WT COB，COX-2 KO COB 中对 PTH 的差异基因反应包括 cAMP 介导的早期反应基因 c-fos 和 Nr4a2 的倍数增加； IGF-1 mRNA 表达增加；并降低 MAP 激酶磷酸酶-1 的 mRNA 表达。 PTH 在 COX-2 KO MSC 培养物中抑制 SOST mRNA 表达 91%，而在 WT 培养物中抑制 67%。我们得出的结论是，内源性 PG 可能通过使 cAMP 通路脱敏来抑制体外对 PTH 的合成代谢反应。 (C) 2008 Elsevier Inc. 保留所有权利。
PTH is a potent bone anabolic agent in vivo but anabolic effects on osteoblast differentiation in vitro are difficult to demonstrate. This study examined the role of cyclooxygenase (COX)-2 and prostaglandin (PG) production in the effects of PTH on osteoblast differentiation in vitro using marrow stromal cell (MSC) and calvarial osteoblast (COB) cultures from COX-2 knockout (KO) and wild type (WT) mice. Cells were treated with PTH (10 nM) or vehicle throughout culture. Alkaline phosphatase (ALP) and osteocalcin (OCN) mRNA levels were measured at days 14 and 21, respectively, and mineralization at day 21. cAMP concentrations were measured in the presence of a phosphodiesterase inhibitor. PTH did not stimulate differentiation in cultures from WT mice but significantly increased ALP and OCN mRNA expression 6- to 7-fold in KO MSC cultures and 2- to 4-fold in KO COB cultures. PTH also increased mineralization in both KO MSC and COB cultures. Effects in KO cells were mimicked in WT MSC cultures treated with NS-398, an inhibitor of COX-2 activity. PTH increased cAMP concentrations similarly in WT and KO COBs. Differential gene responses to PTH in COX-2 KO COBs relative to WT COBs included greater fold-increases in the cAMP-mediated early response genes, c-fos and Nr4a2; increased IGF-1 mRNA expression; and decreased mRNA expression of MAP kinase phosphatase-1. PTH inhibited SOST mRNA expression 91% in COX-2 KO MSC cultures compared to 67% in WT cultures. We conclude that endogenous PGs inhibit the anabolic responses to PTH in vitro, possibly by desensitizing cAMP pathways. (C) 2008 Elsevier Inc. All rights reserved.