Sirtuin 3 is required for osteogenic differentiation through maintenance of PGC-1ɑ-SOD2-mediated regulation of mitochondrial function.
Sirtuin 3 is required for osteogenic differentiation through maintenance of PGC-1ɑ-SOD2-mediated regulation of mitochondrial function.
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DOI：
10.7150/ijbs.17053
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发表时间：
2017
影响因子：
9.2
通讯作者：
Sun H
中科院分区：
文献类型：
--
作者：
Ding Y;Yang H;Wang Y;Chen J;Ji Z;Sun H
成骨分化对维持骨稳态至关重要。Sirtuin 3 （SIRT3）是sirtuins家族的成员，是一种关键的去乙酰化酶，调节许多关键蛋白。在目前的研究中，我们旨在通过小鼠成骨前MC3T3-E1细胞阐明SIRT3在成骨分化中的作用及其可能的机制。分化后的MC3T3-E1细胞中SIRT3的表达显著升高。敲低SIRT3可显著降低MC3T3-E1分化细胞碱性磷酸酶（ALP）染色、矮子相关转录因子2 （Runx2）、ⅰ型胶原蛋白1 （Col1 α 1）、骨钙素mRNA表达。过表达野生型而非突变型SIRT3可以逆转SIRT3敲低导致的ALP染色下降。SIRT3敲低后，复合物I、II、III、IV和V活性、耗氧量和线粒体膜电位显著降低。SIRT3敲低降低了线粒体密度，增加了线粒体大小，降低了NRF1和TFAM的表达。SIRT3敲低可降低SOD2 mRNA和蛋白表达，增加ROS水平。过表达SOD2可显著抑制SIRT3敲低导致的线粒体功能下降和成骨分化。SIRT3敲低导致PGC-1蛋白表达显著降低，但mRNA表达不明显。过表达野生型而非突变型SIRT3可以逆转SIRT3敲低导致的PGC-1蛋白表达降低。此外，我们检测到SIRT3和PGC-1 α之间的直接相互作用，SIRT3敲低降低了SIRT3和PGC-1 α之间的相互作用，导致PGC-1 α蛋白稳定性和PGC-1 α在SOD2启动子中的结合降低。PGC-1 γ过表达阻断SIRT3敲低诱导的SOD2表达降低，ROS水平升高，线粒体功能和生物发生降低，导致成骨改善。总的来说，这些数据为SIRT3在成骨分化中的作用提供了更好的理解。
Osteogenic differentiation is crucial for the maintenance of bone homeostasis. Sirtuin 3 (SIRT3), a member of sirtuins family, functions as a critical deacetylase that regulates many key proteins. In the current study, we aimed to clarify the role of SIRT3 in osteogenic differentiation and the possible mechanisms, using mouse pre-osteoblastic MC3T3-E1 cells. Expression of SIRT3 was substantially increased in differentiated MC3T3-E1 cells. Knock down of SIRT3 significantly decreased alkaline phosphatase (ALP) staining, and mRNA expression of runt-related transcription factor 2 (Runx2) and collagen type I ɑ 1 (Col1ɑ1), and osteocalcin in differentiated MC3T3-E1 cells. Overexpression of wild type but not mutant SIRT3 could reverse SIRT3 knockdown-resulted decrease of ALP staining. Complex I, II, III, IV, and V activities, oxygen consumption and mitochondrial membrane potential were significantly decreased by SIRT3 knockdown. Moreover, SIRT3 knockdown reduced mitochondrial density, increased mitochondrial size and decreased the expression of NRF1 and TFAM. Knock down of SIRT3 decreased mRNA and protein expression of SOD2 and increased ROS level. Overexpression of SOD2 significantly suppressed SIRT3 knockdown-induced decrease of mitochondrial function and osteogenic differentiation. SIRT3 knockdown resulted in a significant decrease of PGC-1ɑ protein expression but not mRNA expression. Overexpression of wild type but not mutant SIRT3 could reverse SIRT3 knockdown-resulted decrease of PGC-1ɑ protein expression. Moreover, we detected a direct interaction between SIRT3 and PGC-1ɑ and SIRT3 knockdown reduced SIRT3 and PGC-1ɑ interaction, resulting in a reduction of PGC-1ɑ protein stability and PGC-1ɑ-binding in the promoters of SOD2. Overexpression of PGC-1ɑ blocked SIRT3 knockdown-induced decrease of SOD2 expression, increase of ROS level, and decrease of mitochondrial function and biogenesis, leading to improvement of osteogenesis. Overall, the data provide a better understanding of the role of SIRT3 in osteogenic differentiation.