Si Xiaoxing, Chen Wen, Guo Xudong, Chen Long, Wang Guiying, Xu Yanxin, Kang Jiuhong
Clinical and Translational Research Center of Shanghai First Maternity & Infant Health Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China.
PLoS One. 2013 Oct 18;8(10):e76699. doi: 10.1371/journal.pone.0076699. eCollection 2013.
Sirt2, a member of the NAD(+)-dependent protein deacetylase family, is increasingly recognized as a critical regulator of the cell cycle, cellular necrosis and cytoskeleton organization. However, its role in embryonic stem cells (ESCs) remains unclear. Here we demonstrate that Sirt2 is up-regulated during RA (retinoic acid)-induced and embryoid body (EB) differentiation of mouse ESCs. Using lentivirus-mediated shRNA methods, we found that knockdown of Sirt2 compromises the differentiation of mouse ESCs into ectoderm while promoting mesoderm and endoderm differentiation. Knockdown of Sirt2 expression also leads to the activation of GSK3β through decreased phosphorylation of the serine at position 9 (Ser9) but not tyrosine at position 216 (Tyr216). Moreover, the constitutive activation of GSK3β during EB differentiation mimics the effect of Sirt2 knockdown, while down-regulation of GSK3β rescues the effect of Sirt2 knockdown on differentiation. In contrast to the effect on lineage differentiation, Sirt2 knockdown and GSK3β up-regulation do not change the self-renewal state of mouse ESCs. Overall, our report reveals a new function for Sirt2 in regulating the proper lineage commitment of mouse ESCs.
Sirt2是NAD(+)依赖的蛋白质脱乙酰酶家族成员，越来越被认为是细胞周期、细胞坏死和细胞骨架组织的关键调节因子。然而，其在胚胎干细胞（ESC）中的作用仍不清楚。在此我们证明，在视黄酸（RA）诱导的和小鼠胚胎干细胞的拟胚体（EB）分化过程中，Sirt2表达上调。利用慢病毒介导的短发夹RNA方法，我们发现敲低Sirt2会损害小鼠胚胎干细胞向外胚层的分化，同时促进中胚层和内胚层的分化。敲低Sirt2表达还会通过降低丝氨酸9（Ser9）而非酪氨酸216（Tyr216）的磷酸化导致GSK3β激活。此外，在EB分化过程中GSK3β的组成型激活模拟了敲低Sirt2的效果，而GSK3β的下调则挽救了敲低Sirt2对分化的影响。与对谱系分化的影响相反，敲低Sirt2和上调GSK3β不会改变小鼠胚胎干细胞的自我更新状态。总体而言，我们的报告揭示了Sirt2在调节小鼠胚胎干细胞正确的谱系定向中的新功能。
