一《Nature》干细胞文章遭质疑

　　

生物通报道，学术上的百家争鸣能有助科学研究的进步，最新一期的《Nature》杂志就上演了这一一幕。2008年3月，德克萨斯M.D Anderson肿瘤中心的科学家称，找到了一种可以维持胚胎干细胞多能性的关键转录因子。

 

2008年的REST maintains self-renewal and pluripotency of embryonic stem cells文章称，针对小鼠胚胎干细胞的研究发现，REST能够抑制一种名为microRNA-21或者miR-21的特定小RNA分子。MiR-21具有抑制胚胎干细胞自我更新的能力并且与某些和胚胎干细胞自我更新能力相关的如：Oct4,Nanog,Sox2以及c-Myc 等关键调节子表达的缺失有关。REST可以通过抑制miR-21来阻止上述事件的发生，从而维持胚胎干细胞的自我更新能力和多潜能性。（关于2008年的文章详细情况可查看生物通前期报道，

http://www.ebiotrade.com/newsf/2008-3/2008326103334.htm）

 

 

本周（2月26日，周四）最新的《Nature》同期发表了两篇文章，反驳REST是胚胎干细胞多能性的关键因子的观点。

一篇是由英国伦敦皇家学院（King’s College London）发表题为：Is REST a regulator of pluripotency?的文章；一篇是由帝国医学研究学院（Imperial College School of Medicine）发表的题为：Is REST required for ESC pluripotency?的文章。

 

两篇文章重复REST功能研究实验，英国伦敦皇家学院发现REST并不影响胚胎干细胞的多能性，并且没有抑制miR-21的功能。帝国医学研究学院研究发现将小鼠胚胎干细胞中的REST基因剔除并不影响其多能性。

 

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三原文摘要

REST maintains self-renewal and pluripotency of embryonic stem cells

【Abstract】

The neuronal repressor REST (RE1-silencing transcription factor; also called NRSF) is expressed at high levels in mouse embryonic stem (ES) cells1, but its role in these cells is unclear. Here we show that REST maintains self-renewal and pluripotency in mouse ES cells through suppression of the microRNA miR-21. We found that, as with known self-renewal markers, the level of REST expression is much higher in self-renewing mouse ES cells than in differentiating mouse ES (embryoid body, EB) cells. Heterozygous deletion of Rest (Rest +/-) and its short-interfering-RNA-mediated knockdown in mouse ES cells cause a loss of self-renewal—even when these cells are grown under self-renewal conditions—and lead to the expression of markers specific for multiple lineages. Conversely, exogenously added REST maintains self-renewal in mouse EB cells. Furthermore, Rest +/- mouse ES cells cultured under self-renewal conditions express substantially reduced levels of several self-renewal regulators, including Oct4 (also called Pou5f1), Nanog, Sox2 and c-Myc, and exogenously added REST in mouse EB cells maintains the self-renewal phenotypes and expression of these self-renewal regulators. We also show that in mouse ES cells, REST is bound to the gene chromatin of a set of miRNAs that potentially target self-renewal genes. Whereas mouse ES cells and mouse EB cells containing exogenously added REST express lower levels of these miRNAs, EB cells, Rest +/- ES cells and ES cells treated with short interfering RNA targeting Rest express higher levels of these miRNAs. At least one of these REST-regulated miRNAs, miR-21, specifically suppresses the self-renewal of mouse ES cells, corresponding to the decreased expression of Oct4, Nanog, Sox2 and c-Myc. Thus, REST is a newly discovered element of the interconnected regulatory network that maintains the self-renewal and pluripotency of mouse ES cells.

 

Is REST a regulator of pluripotency?

【Abstract】

Establishment and maintenance of the pluripotent state of ESCs is a key issue in stem cell biology and regenerative medicine, and consequently identification of transcription factors that regulate ESC pluripotency is an important goal. Singh et al. 1 claim that the transcriptional repressor REST is such a regulator and that a 50% reduction of REST in ESCs leads to activation of a specific microRNA, miR-21, and that this subsequently results in loss of pluripotency markers and a reciprocal gain in some lineage-specific differentiation markers. In contrast, we show that, in haplodeficient Rest +/- ESCs, we detected no change in pluripotency markers, no precocious expression of differentiated neuronal markers and no interaction of REST with miR-21. It is vital that identification of factors that regulate pluripotency is based on robust, consistent data, and the contrast in data reported here undermines the claim by Singh et al. 1 that REST is such a regulator.

 

Is REST required for ESC pluripotency?

【Abstract】

The DNA-binding protein REST (also called NRSF) is a transcriptional repressor that targets many neuronal genes1, 2 and is abundant in human and mouse pluripotent embryonic stem cells (ESCs)3, 4, 5. In a recent Letter to Nature, Singh et al. 6 suggested that REST controls the self-renewal and pluripotency of ESCs, because they found that ESCs in which a single REST allele was disrupted (Fig. 1a, -geo-stop insertion) had reduced alkaline phosphatase activity and expressed lower levels of several pluripotency-associated genes6. Here we show that partial or complete loss of functional REST protein does not abrogate ESC potential as reflected by marker gene expression. These data are consistent with earlier reports7, 8, and argue that REST is not required for maintaining ESC pluripotency.