Described herein is the finding that increasing the frequency of Zscan4 activation in mouse ES cells not only enhances, but also maintains their developmental potency in long-term cell culture. As the potency increases, even a whole animal can be produced from a single ES cell injected into a 4N blastocyst at an unexpectedly high success rate. The studies disclosed herein indicate that ES cells acquire higher potency by going through the transient Zscan4 activation state more frequently than the regular state. Particularly disclosed herein is the finding that the constitutive presence of Zscan4-ERT2, even in the absence of its usual activator tamoxifen, can increase the frequency of endogenous Zscan4 activation in ES cells, resulting in the increase of developmental potency of the ES cells. Accordingly, provided herein are Zscan4-ERT2 fusion proteins and nucleic acid molecules and vectors encoding Zscan4-ERT2 fusion proteins. Further provided are methods of prolonging and/or enhancing stem cell pluripotency using the disclosed Zscan4-ERT2 nucleic acid molecules and fusion proteins.本明細書は、マウスＥＳ細胞でＺｓｃａｎ４活性化の頻度を増加させることが、長期的な細胞培養での発生能を増大させるだけでなく、維持するという所見を記載する。特に、本明細書は、Ｚｓｃａｎ４－ＥＲＴ２の構成存在が、その通常の活性因子であるタモキシフェンの存在下でさえ、ＥＳ細胞における内因性Ｚｓｃａｎ４活性化の頻度を高め、結果として、ＥＳ細胞の発生能の増加をもたらすという所見を開示する。従って、本明細書には、Ｚｓｃａｎ４－ＥＲＴ２融合タンパク質及び核酸分子及びＺｓｃａｎ４－ＥＲＴ２融合タンパク質をコードするベクターが提供される。さらに、Ｚｓｃａｎ４－ＥＲＴ２核酸分子及び融合タンパク質を用いて、幹細胞の多能性を持続させ及び／又は増大させる方法が提供される。
