Post-translational regulation of Oct4 transcriptional activity.
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.
Saxe
Jonathan P
JP
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America. jonathan.saxe@yale.edu
Tomilin
Alexey
A
Schöler
Hans R
HR
Plath
Kathrin
K
Huang
Jing
J
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D019281:Dimerization; D005786:Gene Expression Regulation; D051379:Mice; D008958:Models, Molecular; D050814:Octamer Transcription Factor-3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D020836:Protein Structure, Quaternary; D015398:Signal Transduction / Q000502:physiology*; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases