KLF4 and PBX1 directly regulate NANOG expression in human embryonic stem cells

Area of Science:

• Stem Cell Biology
• Molecular Genetics
• Epigenetics

Background:

• Understanding human embryonic stem cell (hESC) self-renewal and pluripotency requires insight into core transcription factor regulation.
• The specific transcriptional regulation of NANOG in hESCs has remained largely undetermined.

Purpose of the Study:

• To identify novel transcriptional regulators of NANOG in hESCs.
• To elucidate the molecular mechanisms maintaining hESC pluripotency and self-renewal.

Main Methods:

• Established a NANOG promoter luciferase reporter assay for monitoring hESC pluripotency.
• Conducted functional cDNA screens and NANOG promoter characterization.
• Utilized chromatin immunoprecipitation and electrophoretic mobility shift assays to confirm transcription factor binding.

Main Results:

• Identified KLF4 and PBX1 as novel transcriptional regulators of NANOG in hESCs.
• Demonstrated that KLF4 and PBX1 maintain the pluripotent and undifferentiated state of hESCs.
• Showed KLF4 and PBX1 directly bind to the NANOG promoter and enhancer regions, upregulating NANOG expression.
• Confirmed functional redundancy within SP/KLF and PBX families and synergistic activation of NANOG by KLF4/PBX1 with OCT4/SOX2.

Conclusions:

• KLF4 and PBX1 are novel upstream activators of NANOG, critical for hESC self-renewal.
• These findings provide new insights into the regulatory network maintaining hESC pluripotency.