Submersion and hypoxia inhibit ciliated cell differentiation in a notch-dependent manner

Area of Science:

• Respiratory biology
• Cell differentiation
• Epithelial cell biology

Background:

• Airway epithelium comprises diverse cell types originating from progenitors.
• Ciliated cells are crucial for airway function, but their differentiation control is unclear.
• In vitro culture at air-liquid interface promotes, while submersion inhibits, ciliated cell differentiation.

Purpose of the Study:

• Investigate the mechanism by which submerged culture conditions inhibit ciliated cell differentiation.
• Determine the role of hypoxia and Notch signaling in regulating ciliated cell fate.
• Identify molecular targets for promoting ciliated cell differentiation in airway epithelium.

Main Methods:

• Culturing normal human bronchial epithelial (NHBE) cells under submerged and air-liquid interface conditions.
• Assessing gene expression of ciliogenesis factors (multicilin, FOXJ1) under varying oxygen and signaling conditions.
• Utilizing γ-secretase inhibitor (DAPT) and Notch pathway manipulation to evaluate signaling involvement.

Main Results:

• Submerged and hypoxic conditions significantly reduced multicilin and Forkhead box J1 (FOXJ1) expression.
• Treatment with DAPT restored gene expression and ciliated cell differentiation in submerged, hypoxic NHBE cells.
• Notch pathway activation, confirmed by intracellular domain overexpression, was found to repress ciliogenesis genes.

Conclusions:

• Submersion and hypoxia induce a cellular environment that prevents ciliated cell differentiation.
• Notch signaling plays a critical role in repressing ciliogenesis by inhibiting key transcription factors.
• These findings elucidate molecular mechanisms regulating human bronchial epithelial cell differentiation and offer potential therapeutic targets.