Spatial-specific TGF-beta1 adenoviral expression determines morphogenetic phenotypes in embryonic mouse lung

Area of Science:

• Developmental Biology
• Molecular Biology
• Cell Signaling

Background:

• The precise role of transforming growth factor-beta (TGF-β) signaling in mammalian organ morphogenesis is not fully understood.
• TGF-β is a crucial regulator of cell growth, differentiation, and extracellular matrix production.

Purpose of the Study:

• To investigate the spatial and temporal effects of overexpressing active and latent TGF-β1 on embryonic mouse lung branching morphogenesis.
• To determine the impact of TGF-β1 on specific gene expression in lung epithelial and mesenchymal cells.

Main Methods:

• Replication-deficient adenoviral vectors encoding TGF-β1 cDNAs were used for gene transfer into embryonic mouse lungs.
• Lungs were treated via intra-tracheal micro-injection (epithelium) or submersion (pleura and mesenchyme).
• Branching morphogenesis was quantified, and gene expression (SP-C, SP-B, fibronectin, MGP) was analyzed using RT-PCR.

Main Results:

• Overexpression of active TGF-β1 in the lung epithelium inhibited branching morphogenesis by 36% and downregulated SP-C and SP-B mRNA.
• Delivery of active TGF-β1 to the pleura/mesenchyme induced fibronectin and MGP mRNA but did not affect branching.
• Latent TGF-β1 overexpression had no significant effect on lung branching or gene expression, regardless of delivery method.

Conclusions:

• Activated TGF-β1, not its latent form, is critical for regulating spatial effects in lung morphogenesis.
• The route of administration determines whether active TGF-β1 inhibits branching/epithelial gene expression or induces matrix gene expression.
• TGF-β activation is a key regulatory point for spatial signaling during embryonic lung development.