Stereospecific NANOG PEST Stabilization by Pin1

Area of Science:

• Biochemistry
• Molecular Biology
• Stem Cell Biology

Background:

• NANOG protein levels are critical for maintaining stem cell pluripotency.
• Fluctuations in NANOG concentration can trigger spontaneous cell differentiation.
• Pin1, a phosphorylation-dependent prolyl isomerase, has been previously implicated in NANOG stabilization.

Purpose of the Study:

• To investigate the molecular interactions between Pin1 and the NANOG unstructured N-terminal domain.
• To elucidate the role of phosphorylation and cis-trans isomerization in NANOG-Pin1 binding.
• To explore the potential of NANOG PEST peptides as inhibitors for cancer stem cell therapy.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy was employed to study protein-peptide interactions.
• Analysis of NANOG PEST peptides with varying phosphorylation states and cis-conformer populations.
• Quantification of binding affinity between Pin1 domains (WW and PPIase) and NANOG peptides.

Main Results:

• Phosphorylation of NANOG PEST peptides significantly increases their affinity for Pin1.
• Increased cis-PEST conformers enhance the binding of NANOG peptides to the Pin1 prolyl isomerase (PPIase) domain.
• A 5-10 fold increase in NANOG binding to Pin1's WW and PPIase domains was observed with enhanced phosphorylation and cis-Pro content.

Conclusions:

• The study elucidates the molecular mechanism by which Pin1 stabilizes NANOG through phosphorylation-dependent binding.
• NANOG PEST peptides with enhanced cis-population show increased affinity for Pin1, suggesting a regulatory role.
• These findings highlight the potential of targeting the Pin1-NANOG interaction to disrupt cancer stem cell stabilization.