Mechanical input restrains PPARγ2 expression and action to preserve mesenchymal stem cell multipotentiality.
Mechanical input restrains PPARγ2 expression and action to preserve mesenchymal stem cell multipotentiality.
复制标题
DOI：
10.1016/j.bone.2012.08.122
复制
发表时间：
2013-01
期刊：
影响因子：
4.1
通讯作者：
Rubin J
中科院分区：
文献类型：
--
作者：
Case N;Thomas J;Xie Z;Sen B;Styner M;Rowe D;Rubin J
运动产生的信号在骨髓内具有促成骨和抗脂肪作用。体外研究表明，机械信号通过激活 β-catenin 和限制 PPARγ2 表达，直接阻断脂肪形成分化。机械生成的 β-连环蛋白是否可以在 PPARγ 反式激活过程中抑制脂肪生成尚不清楚。我们评估了机械信号限制 PPARγ 激活远端骨髓间充质干细胞 (mdMSC) 脂肪生成的能力。首先，我们确定，在罗格列酮 (1-25 μM) 存在的情况下，mdMSC 在 2-4 天内获得脂肪形成表型，并且通过 GSK3β 抑制激活 β-连环蛋白会干扰这一过程。同样，机械应变（3600 个循环，每天 2% 应变）在第 3 天抑制脂肪生成，防止罗格列酮诱导的 PPARγ 上调以及 aP2 和脂联素蛋白表达。为了评估 PPARγ 表达的减少是否是抗脂肪形成作用所必需的，PPARγ2 过度表达：尽管 PPARγ2 及其配体含量丰富，但机械应变和 GSK3β 抑制都阻止了 aP2 和脂联素蛋白的表达。为了了解经历机械应变的单细胞的命运，我们从表达 aP2-GFP 报告基因的小鼠中产生了 mdMSC。罗格列酮治疗3天诱导超过80%的细胞表达GFP。按 GFP 表达分类显示，最高 20% 的 aP2-GFP 表达细胞负责大部分脂肪形成蛋白表达。这种高表达的 GFP 部分对成骨刺激的反应能力降低：BMP-2 处理使 osterix 增加 12 倍，而 BMP-2 处理底部 75% 的 GFP 表达细胞导致 osterix 表达增加 42 倍。这表明高表达的aP2-GFP细胞代表了更多终末分化的脂肪细胞，其多能性降低。对用罗格列酮处理的 aP2-GFP mdMSC 应用机械应变，导致上层细胞部分的大小减少两倍，表明机械应变将 MSC 保持在多能状态。我们的数据表明，机械应变通过限制 PPARγ2 表达和阻止 PPARγ 作用来限制脂肪生成，从而保护 MSC 进入其他谱系的潜力。
Exercise-generated signals are pro-osteogenic and anti-adipogenic within the marrow. In vitro studies indicate that mechanical signals directly block adipogenic differentiation through activation of β-catenin and by limiting PPARγ2 expression. Whether mechanically generated β-catenin can inhibit adipogenesis during PPARγ transactivation is unknown. We evaluated the ability of mechanical signals to limit adipogenesis in marrow derived mesenchymal stem cells (mdMSC) distal to activation of PPARγ. First, we established that mdMSC attained an adipogenic phenotype within 2-4 days in the presence of rosiglitazone (1-25 μM) and that β-catenin activation via GSK3β inhibition interfered with this process. Similarly, mechanical strain (3600 cycles, 2% strain daily) inhibited adipogenesis at 3 days, preventing rosiglitazone-induced PPARγ upregulation as well as aP2 and adiponectin protein expression. To assess whether a reduction in PPARγ expression was necessary for anti-adipogenic action, PPARγ2 was overexpressed: both mechanical strain and GSK3β inhibition prevented expression of aP2 and adiponectin proteins despite abundant PPARγ2 and its ligand. To understand the fate of single cells experiencing mechanical strain we generated mdMSC from aP2-GFP reporter expressing mice. Rosiglitazone treatment for 3 days induced GFP expression in more than 80% of cells. Sorting by GFP expression revealed that the highest 20% of aP2-GFP expressing cells was responsible for the majority of adipogenic protein expression. This highly expressing GFP fraction had a reduced ability to respond to an osteogenic stimulus: BMP-2 treatment increased osterix by 12-fold in contrast to the 42-fold increase in osterix expression that resulted from BMP-2 treatment of the bottom 75% of GFP expressing cells. This suggested that highly expressing aP2-GFP cells represented more terminally differentiated adipocytes, with reduced multipotentiality. Application of mechanical strain to aP2-GFP mdMSC treated with rosiglitazone caused a two-fold decrease in the size of the upper cell fraction, suggesting that mechanical strain preserved MSC in a multipotent state. Our data show that mechanical strain restricts adipogenesis both by limiting PPARγ2 expression and by preventing PPARγ action, protecting the potential of MSC to enter other lineages.
登录
查看更多内容
炎症和代谢疾病中的脂肪因子。
DOI：
10.1038/nri2921
发表时间：
2011-02
期刊：
Nature reviews. Immunology
影响因子：
--
作者：
通讯作者：
--
影响因子：
2.8
作者：
Case, Natasha;Xie, Zhihui;Sen, Buer;Styner, Maya;Zou, Minxu;O'Conor, Chris;Horowitz, Mark;Rubin, Janet
通讯作者：
Rubin, Janet
影响因子：
4.9
作者：
Farmer, SR
通讯作者：
Farmer, SR
DOI：
10.1073/pnas.1036475100
发表时间：
2003-05-13
影响因子：
11.1
作者：
Bonyadi, M;Waldman, SD;Stanford, WL
通讯作者：
Stanford, WL
影响因子：
3
作者：
Bu, Shumin;Chen, Yu;Ji, Gang
通讯作者：
Ji, Gang