Jung Yu Jin, Park Woong, Noh Jeong Mi, Kang Kyung Pyo, Nguyen-Thanh Tung, Han Myung Kwan, Kim Won
Department of Internal Medicine, Jeonbuk National University Medical School, 634-18, Keum-Am dong, Jeonju 560-180, Republic of Korea; Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Republic of Korea.
Department of Internal Medicine, Jeonbuk National University Medical School, 634-18, Keum-Am dong, Jeonju 560-180, Republic of Korea.
Stem Cell Res. 2020 Apr;44:101771. doi: 10.1016/j.scr.2020.101771. Epub 2020 Mar 17.
SIRT1 (NAD-dependent deacetylase) plays a suppressive role during the late stages of adipogenesis. However, the effects of SIRT1 on the early phases of adipogenic differentiation from embryonic stem cells (ESCs) are poorly understood. We employed Sirt1 and Sirt1 mouse embryonic stem cells (mESCs) to evaluate the role of SIRT1 during the early stage mESC differentiation to adipocytes in response to retinoic acid (RA) treatment. Treatment with EX527 (a SIRT1 inhibitor) during the early phase and SIRT1 knockout both significantly diminished differentiation to mature adipocytes. Expressions of marker genes of preadipocytes, brown adipocytes, and brite cells were significantly lower in Sirt1 mESCs than in Sirt1 mESCs. Furthermore, SIRT1 knockout reduced RA-induced RA receptor (RAR)α and RARβ mRNA and protein expressions during early adipocyte differentiation. Nuclear receptor corepressor 1 (NCOR1), a negative regulator of RAR signaling, expression, and acetylation levels were higher in Sirt1 than in Sirt1 mESCs. After RA treatment, chromatin immunoprecipitation assays using an antibody against NCOR1, revealed that NCOR1 binding to RARβ promoters was significantly lower in Sirt1 mESCs than in Sirt1 mESCs, and luciferase reporter assays showed SIRT1 knockdown decreased RA-induced RARα activity. Taken together, these observations show SIRT1 is required during the early phase of mESC adipogenesis and that SIRT1 deficiency inhibits adipogenesis by increasing NCOR1 acetylation and down-regulating the expressions of RARα and RARβ.
沉默调节蛋白1（NAD依赖性脱乙酰酶）在脂肪生成后期发挥抑制作用。然而，沉默调节蛋白1对胚胎干细胞（ESC）向脂肪细胞分化早期阶段的影响却知之甚少。我们使用野生型和沉默调节蛋白1基因敲除的小鼠胚胎干细胞（mESC）来评估沉默调节蛋白1在mESC响应视黄酸（RA）处理向脂肪细胞分化早期阶段的作用。在早期阶段用EX527（一种沉默调节蛋白1抑制剂）处理以及敲除沉默调节蛋白1基因均显著减少了向成熟脂肪细胞的分化。前脂肪细胞、棕色脂肪细胞和米色脂肪细胞标志物基因的表达在沉默调节蛋白1基因敲除的mESC中显著低于野生型mESC。此外，在脂肪细胞分化早期，敲除沉默调节蛋白1基因降低了RA诱导的视黄酸受体（RAR）α和RARβ的mRNA及蛋白表达。核受体辅阻遏物1（NCOR1）是RAR信号传导的负调节因子，其在沉默调节蛋白1基因敲除的mESC中的表达及乙酰化水平高于野生型mESC。RA处理后，使用抗NCOR1抗体进行的染色质免疫沉淀试验表明，沉默调节蛋白1基因敲除的mESC中NCOR1与RARβ启动子的结合显著低于野生型mESC，荧光素酶报告基因试验表明敲低沉默调节蛋白1可降低RA诱导的RARα活性。综上所述，这些观察结果表明沉默调节蛋白1在mESC脂肪生成早期是必需的，且沉默调节蛋白1缺乏通过增加NCOR1乙酰化和下调RARα及RARβ的表达来抑制脂肪生成。
