KLF4 Nuclear Export Requires ERK Activation and Initiates Exit from Naive Pluripotency

• Published in: Stem cell reports Vol. 10; no. 4; pp. 1308 - 1323
• Main Authors: Dhaliwal, Navroop K., Miri, Kamelia, Davidson, Scott, Tamim El Jarkass, Hala, Mitchell, Jennifer A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10.04.2018; Elsevier
• Subjects: Active Transport, Cell Nucleus; Animals; Cell Cycle; Cell Differentiation; Cell Nucleus - metabolism; Down-Regulation; embryonic stem cell; Enzyme Activation; ERK; Exportin 1 Protein; Extracellular Signal-Regulated MAP Kinases - metabolism; Karyopherins - metabolism; KLF4; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors - metabolism; Mice; Mouse Embryonic Stem Cells; Nanog Homeobox Protein - metabolism; nuclear export; Nuclear Export Signals; Phosphorylation; Phosphoserine - metabolism; pluripotency; Pluripotent Stem Cells - cytology; Pluripotent Stem Cells - metabolism; Protein Binding; proximity ligation amplification; Receptors, Cytoplasmic and Nuclear - metabolism; Signal Transduction; transcription factor; XPO1; transcription factor; XPO1; embryonic stem cell; nuclear export; pluripotency; KLF4; proximity ligation amplification; ERK
• ISSN: 2213-6711; 2213-6711
• DOI: 10.1016/j.stemcr.2018.02.007

Cooperative action of a transcription factor complex containing OCT4, SOX2, NANOG, and KLF4 maintains the naive pluripotent state; however, less is known about the mechanisms that disrupt this complex, initiating exit from pluripotency. We show that, as embryonic stem cells (ESCs) exit pluripotency, KLF4 protein is exported from the nucleus causing rapid decline in Nanog and Klf4 transcription; as a result, KLF4 is the first pluripotency transcription factor removed from transcription-associated complexes during differentiation. KLF4 nuclear export requires ERK activation, and phosphorylation of KLF4 by ERK initiates interaction of KLF4 with nuclear export factor XPO1, leading to KLF4 export. Mutation of the ERK phosphorylation site in KLF4 (S132) blocks KLF4 nuclear export, the decline in Nanog, Klf4, and Sox2 mRNA, and differentiation. These findings demonstrate that relocalization of KLF4 to the cytoplasm is a critical first step in exit from the naive pluripotent state and initiation of ESC differentiation. [Display omitted] •KLF4 nuclear export occurs as ESCs exit naive pluripotency•Active ERK and XPO1 interaction with KLF4 is required for nuclear export•KLF4 S132, an ERK phosphorylation site in KLF4, is required for nuclear export•Blocking KLF4 nuclear export prevents ESC differentiation Dhaliwal and colleagues show that KLF4 is exported from the nucleus to initiate embryonic stem cell differentiation. KLF4 nuclear export is caused by FGF-MEK-ERK signaling whereby activated ERK phosphorylates KLF4, allowing interaction with nuclear export factor Xportin1. Blocking KLF4 nuclear export prevents embryonic stem cell exit from naive pluripotency and slows development of the embryo.