摘要
核基质蛋白4(nuclear matrix protein4,Nmp4)是一种具有核质穿梭功能的结构性转录因子.主要通过负调控调节成骨细胞分化和增殖,抑制骨密度及骨量增加,而Nmp4是否调节成骨细胞凋亡,还未有相关报道.本课题通过分离Nmp4基因敲除(Nmp4-KO)和野生型(WT)小鼠原代成骨细胞,以肿瘤坏死因子(TNF-α)为凋亡诱导手段,研究了Nmp4对成骨细胞凋亡的影响及其作用机制.体外细胞实验发现,Nmp4-KO显著抑制TNF-α诱导的成骨细胞内caspase-3激活.Nmp4-KO促进细胞外信号调节激酶(Erk)和丝氨酸/苏氨酸蛋白激酶(Akt)信号途径的激活,抑制c-Jun氨基末端激酶(JNK)磷酸化,从而对抗成骨细胞凋亡.TNF-α诱导处理可增强成骨细胞核因子NFκB磷酸化及其核转位,但Nmp4基因缺失无进一步促进作用.未经诱导处理的Nmp4-KO细胞内NFκB磷酸化水平显著高于WT对照.此外,TNF-α诱导处理促使线粒体途径信号分子Bad磷酸化及Bcl-xl表达水平适当升高,但在两种细胞表型间无显著差异.这些结果证实,Nmp4基因敲除可促进相关抗凋亡信号分子的激活和表达,抑制促凋亡信号的激活,进而抑制成骨细胞凋亡的发生.
Nuclear matrix protein 4 （Nmp4） , a nucleocytoplasmic shuttling transcription factor, acts via negative regulation on the differentiation and proliferation of osteoblasts and suppresses the increases in the bone mineral density and bone mass in vivo. In this study, we investigated whether Nmp4 was involved in regulating apoptosis of primary calvarial osteoblasts isolated from Nmp4 knockout （Nmp4-KO） and widetype （WT） mice. The results showed that Nmp4-deficiency suppressed TNF-αindueed activation of caspase-3 in primary osteoblasts. Furthermore, the associated apoptotic signaling molecules including phosphorylated Erk, Akt and JNK, were detected. After treating with TNF-α（10 ng/mL） and cycloheximide （CHX, 10 μg/mL） for 6 hours, Erk, Akt and JNK were significantly activated in Nmp4- KO and WT osteoblasts. The levels of phosphorylated Erk and Akt in the treated Nmp4-KO osteoblasts were notably higher than that in the treated WT controls. Meanwhile the TNF-αinduced activation of JNK was distinctly inhibited in Nmp4-KO osteoblasts compared with treated WT controls. Two-hour treatment with TNF-α/CHX promoted NFKB （p65） phosphorylation and its nuclear translocation. Interestingly.
出处
《中国生物化学与分子生物学报》
CAS
CSCD
北大核心
2010年第9期828-835,共8页
Chinese Journal of Biochemistry and Molecular Biology
基金
国家留学基金
国家自然科学基金资助(No.30970689)~~
