Abstract
Oct4 is a key component of the molecular circuitry which regulates embryonic stem cell proliferation and differentiation. It is essential for maintenance of undifferentiated, pluripotent cell populations, and accomplishes these tasks by binding DNA in multiple heterodimer and homodimer configurations. Very little is known about how formation of these complexes is regulated, or the mechanisms through which Oct4 proteins respond to complex extracellular stimuli which regulate pluripotency. Here, we provide evidence for a phosphorylation-based mechanism which regulates specific Oct4 homodimer conformations. Point mutations of a putative phosphorylation site can specifically abrogate transcriptional activity of a specific homodimer assembly, with little effect on other configurations. Moreover, we performed bioinformatic predictions to identify a subset of Oct4 target genes which may be regulated by this specific assembly, and show that altering Oct4 protein levels affects transcription of Oct4 target genes which are regulated by this assembly but not others. Finally, we identified several signaling pathways which may mediate this phosphorylation and act in combination to regulate Oct4 transcriptional activity and protein stability. These results provide a mechanism for rapid and reversible alteration of Oct4 transactivation potential in response to extracellular signals.
Highlights
The use of embryonic stem cells as therapeutics requires firm understanding of the mechanisms that control their proliferation and differentiation
P19 cells induced to differentiate via aggregation in the presence of retinoic acid turn off Oct4 expression rapidly following induction [19]
Substitution of dimethyl sulfoxide (DMSO) for retinoic acid during P19 cell aggregation results in appearance of various mesodermal cell types [20]
Summary
The use of embryonic stem cells as therapeutics requires firm understanding of the mechanisms that control their proliferation and differentiation. Several recent studies have shed light on transcriptional networks controlled by factors such as Oct (for instance, [6,7]), and begun to address the issue of how extracellular cues are integrated with transcriptional circuits that maintain the pluripotent state [8]. Despite these findings, it is generally not clear how extrinsic cues are integrated within the cell to control the behavior of cell-intrinsic regulators of ES cell pluripotency such as Oct4 [1]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
