TGF-beta and the Smad signaling pathway support transcriptomic reprogramming during epithelial-mesenchymal cell...

Area of Science:

• Cell Biology
• Developmental Biology
• Cancer Biology

Background:

• Epithelial-mesenchymal transition (EMT) is crucial for tissue development and cancer progression.
• The roles of specific transforming growth factor-beta (TGF-β) superfamily members in inducing EMT are not fully elucidated.

Purpose of the Study:

• To investigate the specific roles of TGF-β and bone morphogenetic protein (BMP) signaling pathways in inducing EMT.
• To identify key molecular players and genetic networks downstream of TGF-β involved in EMT.

Main Methods:

• Induction of EMT in human and mouse epithelial cells using various TGF-β superfamily ligands.
• Analysis of Smad protein involvement using ectopic expression and dominant-negative constructs.
• Transcriptomic analysis to identify TGF-β target genes during EMT kinetics.
• Functional studies using a TGF-β type I receptor incapable of Smad activation.

Main Results:

• TGF-β/activin members, but not BMP members, induce EMT and growth arrest in epithelial cells.
• Smad2, Smad3, and Smad4 are essential for TGF-β-induced EMT, while Smad7 inhibits it.
• Transcriptomic analysis revealed novel TGF-β target genes with ligand-specific responses.
• Smad signaling is critical for regulating gene targets during EMT, including Id2, which influences alpha-smooth muscle actin expression.

Conclusions:

• TGF-β signaling pathways are critical for inducing EMT, distinct from BMP pathways.
• Smad signaling acts as a central mediator for TGF-β-induced EMT and associated gene regulation.
• Deciphering the genetic network downstream of TGF-β provides insights into cell proliferation and EMT control.