Acetylation of sox2 induces its nuclear export in embryonic stem cells

Area of Science:

• Molecular Biology
• Developmental Biology
• Stem Cell Biology

Background:

• Embryonic stem (ES) cells rely on transcription factors like Oct4, Nanog, and Sox2 for pluripotency and differentiation.
• Regulation of these key factors, particularly post-translational modifications of Sox2, remains poorly understood.

Purpose of the Study:

• To investigate the post-translational regulation of Sox2, focusing on acetylation.
• To determine the functional consequences of Sox2 acetylation on its localization, stability, and transcriptional activity.

Main Methods:

• Site-directed mutagenesis to block or mimic acetylation at a key lysine residue in Sox2's nuclear export signal.
• Immunofluorescence to assess Sox2 cellular localization.
• Western blotting to evaluate Sox2 protein levels and ubiquitination.
• Analysis of target gene expression under various acetylation conditions.

Main Results:

• Acetylation of a specific lysine in Sox2's nuclear export signal controls its nuclear retention.
• Blocking acetylation maintains Sox2 nuclear localization and target gene expression, even under differentiation-inducing conditions.
• Mimicking acetylation promotes Sox2 association with the nuclear export machinery.
• Increased cellular acetylation leads to Sox2 degradation via ubiquitination and proteasomal pathways, reducing its transcriptional function.

Conclusions:

• Acetylation is a critical post-translational modification regulating Sox2's nuclear export and stability.
• This acetylation-mediated mechanism plays a significant role in controlling ES cell pluripotency and differentiation.
• The identified regulatory mechanism may be conserved across Sox family members.