Oct4 is a gatekeeper of epithelial identity by regulating cytoskeletal organization in skin keratinocytes

Area of Science:

• Cell Biology
• Developmental Biology
• Molecular Biology

Background:

• Oct4 is a key transcription factor regulating pluripotency.
• Its role in epidermal cells remains largely unexplored.

Purpose of the Study:

• To investigate the functional role of Oct4 in human epidermal keratinocytes.
• To identify molecular mechanisms affected by Oct4 deficiency in skin cells.

Main Methods:

• Generation of OCT4 knockout clonal cell lines from immortalized human skin keratinocytes.
• Phenotypic analysis including cell morphology, migration, adhesion, and cell cycle progression.
• Assessment of cytoskeletal organization (actin), cell-cell junction proteins (E-cadherin, β-catenin, ZO1), and extracellular matrix (fibronectin).
• Transcriptional and chromatin profiling of Oct4-deficient cells.

Main Results:

• Oct4-deficient cells exhibited a mesenchymal-like phenotype: enlarged size, increased migration, and decreased adhesion.
• Cells arrested at the G2/M cell cycle checkpoint.
• Significant alterations in cortical actin organization and stress fiber formation were observed.
• Loss of E-cadherin, β-catenin, and ZO1 at cell-cell contacts and increased fibronectin deposition in the ECM.
• Oct4 regulates genes involved in cytoskeleton, ECM, and differentiation, while preserving epithelial identity via multiple mechanisms.

Conclusions:

• Oct4 plays a critical role in maintaining epidermal cell identity and normal cell cycle progression.
• Oct4 deficiency induces a profound epithelial-to-mesenchymal transition-like state in keratinocytes.
• These findings highlight Oct4's broader function beyond pluripotency, impacting skin cell biology.