Rapamycin Affects Palmitate-Induced Lipotoxicity in Osteoblasts by Modulating Apoptosis and Autophagy
Rapamycin Affects Palmitate-Induced Lipotoxicity in Osteoblasts by Modulating Apoptosis and Autophagy
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DOI：
10.1093/gerona/glz149
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发表时间：
2020-01-01
影响因子：
5.1
通讯作者：
Duque, Gustavo
中科院分区：
文献类型：
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作者：
Al Saedi, Ahmed;Goodman, Craig A.;Duque, Gustavo
骨髓脂肪浸润是骨骼衰老和骨质疏松的标志之一。骨髓脂肪细胞产生大量的棕榈酸（PA）。PA在体外对成骨细胞有毒性，影响其分化、功能和存活。由于雷帕霉素（RAP）诱导的抑制雷帕霉素复合物1（mTORC 1）的目标激活自噬和防止细胞凋亡，我们假设，RAP可以保持成骨细胞的活力，减少PA诱导的脂毒性。将正常人成骨细胞与RAP在脂毒性浓度的PA或载体存在下孵育24和48小时。通过Western印迹定量LC 3蛋白表达水平和直接mTORC 1靶点p70 S6 K1-T389的磷酸化。使用共聚焦荧光成像、lysotracker和活细胞成像研究了溶酶体和自噬体。RAP可减少PA诱导的细胞凋亡。此外，PA诱导的自噬体的形成大大增加，随着时间的推移，RAP在介质中的存在下，显着调节的效果。此外，LC 3 I/II比率在PA诱导的细胞与RAP中更高，而p70 S6 K1-T389在PA和RAP中更低。总之，这项研究强调了在脂毒性条件下，RAP敏感的mTORC 1通路在正常人成骨细胞中的作用。RAP相关疗法可能针对骨质疏松症和骨老化中的特定作用。
Bone marrow fat infiltration is one of the hallmarks of aging and osteoporotic bones. Marrow adipocytes produce substantial amounts of palmitic acid (PA). PA is toxic to bone-forming osteoblasts in vitro, affecting their differentiation, function, and survival. Since rapamycin (RAP)-induced inhibition of target of rapamycin complex 1 (mTORC1) activates autophagy and prevents apoptosis, we hypothesized that RAP may preserve osteoblast viability and reduce PA-induced lipotoxicity. Normal human osteoblasts were incubated with RAP in the presence of a lipotoxic concentration of PA or vehicle for 24 and 48 hours. Expression of LC3 protein levels and the phosphorylation of the direct mTORC1 target p70S6K1-T389 were quantified by Western blot. Lysosomes and autophagosomes were studied using confocal fluorescence imaging, lysotracker, and live-cell imaging. RAP reduced PA-induced apoptosis. In addition, PA-induced autophagosome formation increased substantially over the time-course, an effect that was significantly regulated by the presence of RAP in the media. In addition, LC3I/II ratios were higher in PA-induced cells with RAP whereas p70S6K1-T389 were lower in PA and RAP together. In summary, this study highlights the role of the RAP-sensitive mTORC1 pathway in normal human osteoblasts under lipotoxic conditions. RAP-associated therapies could, potentially, be targeted for specific roles in osteoporosis and aging bone.