Transcriptional regulators ensuring specific gene expression and decision-making at high TGFβ doses

Area of Science:

• Cell Biology
• Molecular Biology
• Cancer Research

Background:

• Transforming growth factor beta (TGFβ) signaling is crucial in regulating cancer progression through cell division, migration, and death.
• The precise mechanisms by which TGFβ signaling dictates specific cellular fates via gene expression remain incompletely understood.

Purpose of the Study:

• To quantitatively link TGFβ signaling dynamics, gene expression patterns, and cellular fate decisions in mammary epithelial cells.
• To elucidate the regulatory mechanisms governing TGFβ-induced gene expression and cellular responses.

Main Methods:

• Utilized SMAD transcription factor imaging, genome-wide RNA sequencing, and morphological assays.
• Developed and applied genome-wide kinetic models to time-resolved signaling and gene expression data.
• Performed knockdown experiments to identify interacting transcription factors and regulatory pathways.

Main Results:

• Demonstrated that most TGFβ target genes are directly regulated by SMADs.
• Identified complex regulatory mechanisms, including delayed responses and dose-dependent amplification, for a subset of genes.
• Discovered feedforward loops involving SMADs and other transcription factors that control delayed and dose-discriminating gene expression.
• Identified early repressors and a late activator critical for robust TGFβ responses and reinforcing epithelial-to-mesenchymal transition.

Conclusions:

• Presented a global overview of TGFβ-dependent gene regulation in mammary epithelial cells.
• Characterized specificity mechanisms, such as feedforward loops and temporal control, that reinforce cellular decision-making in response to TGFβ.
• Highlighted the importance of dose and timing in TGFβ-mediated cellular fate determination during cancer progression.