Hypoxia-Inducible Factor-1α in SM22α-Expressing Cells Modulates Alveolarization

Area of Science:

• Pulmonary Medicine
• Developmental Biology
• Molecular Genetics

Background:

• Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in preterm infants, characterized by impaired alveolar development.
• The role of hypoxia-inducible factor-1α (HIF-1α) in lung development, particularly in specific cell types, is not fully understood.

Purpose of the Study:

• To investigate the cell-specific role of HIF-1α in postnatal lung alveolarization and angiogenesis.
• To determine if HIF-1α in SM22α-expressing mesenchymal cells mediates lung development.

Main Methods:

• Generated cell-specific HIF-1α knockout mice (SM22α-HIF-1α-/-) using Cre-lox technology.
• Utilized single-cell RNA sequencing to identify SM22α-expressing cell subtypes.
• Assessed lung structure, vascularization, and angiopoietin-2 expression in knockout mice and preterm infant samples.

Main Results:

• Deletion of HIF-1α in SM22α-expressing cells resulted in fewer and larger alveoli, persisting into adulthood.
• Reduced microvascular density, elastin organization, and lung vascular branching were observed in knockout mice.
• Pulmonary vascular smooth muscle cells lacking HIF-1α showed decreased angiopoietin-2 expression, impairing angiogenesis.

Conclusions:

• SM22α-specific HIF-1α expression is essential for proper postnatal lung alveolarization and peripheral angiogenesis.
• HIF-1α likely promotes alveolarization by regulating angiopoietin-2 expression in vascular smooth muscle cells.
• Findings suggest a potential therapeutic target for BPD by modulating HIF-1α signaling.