The interaction of Ash2l with Oct4 is critical for Oct4 downstream stemness network

• Main Authors: Yu-Hsien Lee, 李昱賢
• Other Authors: Shih-Hwa Chiou
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/28859986722427536072

碩士 === 國立陽明大學 === 藥理學研究所 === 101 === Pluripotent embryonic stem cells (ESCs) maintain self-renewal and the potential for rapid response to differentiation cues. Pluripotent stem cells (PSCs) have unique transcriptional regulatory networks and epigenetic states that are involved in maintaining pluripotency. There is well known about the establishment and maintenance of ES cell-specific transcription were regulated by a variety of specific transcriptional activators such as Oct4, Sox2 and Nanog. Despite the well-documented functions of these core activators, very little is known about an ES cell specific co-activator(s) involved in ES cell transcriptional core circuits. Ash2l, a core subunit of the histone 3 lysine 4 (H3K4) methyltransferase (HMT) complex, positively correlates with the undifferentiated state and is a regulator of ES cell self-renewal. However the function of Ash2l may be as a transcriptional regulator. The HMT complex components Wdr5 and Dpy30 had been find out contributed ESCs features. Therefore we sought to test the role of Ash2l during stem cell and cellular reprogramming by siRNA knockdown. We demonstrated that Ash2l, an ‘‘effector’’ of H3K4 methylation, interacts with the pluripotency transcription factor Oct4 by co-immunoprecipitation. The POU homeodomain transcription factor Oct4 (Pou5f1) is an essential mediator of the embryonic stem cell state. Next we confirmed the interaction between Ash2l and Oct4 enhances Oct4 bind its’ promoter by luciferase assay. In further to our data we found that Ash2l depletion induced the collapse of the extended ES cell transcriptional network by gene expression of stemness markers. Notably, we observed depletion of Ash2l led to drastic reduction of iPS cell formation. Overall we established that Ash2l is required for the initial reconfiguration phase of somatic cell reprogramming. We propose that the Ash2l-Oct4 partnership enhances Oct4 expression through transcriptional activation of its promoter and activated downstream genes expression. Summarized our finding, Ash2l is essential for maintenance for of ES cell pluripotency as well as somatic cell reprogramming by acting as a stem cell cofactor.