Modulation of STAT3 phosphorylation by PTPN2 inhibits naïve pluripotency of embryonic stem cells

Area of Science:

• Stem cell biology
• Molecular signaling
• Epigenetics

Background:

• Leukemia inhibitory factor (LIF) signaling activates STAT3 phosphorylation at tyrosine 705 (STAT3pY705), crucial for mouse embryonic stem cell (mESC) self-renewal and epiblast stem cell (EpiSC) reprogramming.
• STAT3pY705 activation, primarily via Janus kinases, is key to maintaining naïve pluripotency.
• The mechanisms regulating the decrease of STAT3pY705 levels in mESCs remain incompletely understood.

Purpose of the Study:

• To investigate the role of protein tyrosine phosphatase N2 (PTPN2) in regulating STAT3 activity and mouse embryonic stem cell (mESC) differentiation.
• To elucidate the contribution of PTPN2-mediated STAT3 regulation to the maintenance of naïve pluripotency.

Main Methods:

• CRISPR/Cas9 gene editing to generate PTPN2 knockout mESCs.
• PTPN2 knockdown experiments.
• Overexpression of STAT3 in epiblast stem cells (EpiSCs).
• Assessment of mESC differentiation and colony formation assays.

Main Results:

• Upregulation of PTPN2 inhibits STAT3 activity by reducing STAT3pY705 levels, consequently promoting mESC differentiation.
• PTPN2 knockout via CRISPR/Cas9 significantly delays mESC differentiation.
• PTPN2 knockdown enhances the generation of mESC-like colonies in STAT3-overexpressing EpiSCs.

Conclusions:

• PTPN2 acts as a negative regulator of STAT3 activity, influencing the balance between stem cell self-renewal and differentiation.
• PTPN2-mediated regulation of STAT3 phosphorylation is a critical factor contributing to the exit of ESCs from the pluripotent ground state.
• These findings provide new insights into the molecular network governing naïve pluripotency and stem cell fate decisions.