Notch gets transformed

Cells exist in complicated environments filled with reinforcing and conflicting signals. Three recent papers (Blokzijl et al., page 723; Takizawa et al., 2003. Nucl. Acids. Res. 31:5723–5731; Dahlqvist et al., 2003. Development. 10.1242/dev.00834) describe a link between pathways downstream of two of the most important of these signals: Notch and the TGF-β/BMP systems.

Both signaling pathways trigger the release of initially receptor-localized species—the Notch intracellular domain (NICD) and the Smads, respectively—that then enter the nucleus. And recent microarray results suggested that both pathways converge on at least one common target gene. Now, Blokzijl et al. demonstrate that Notch and Smad3 (a protein released from the transforming growth factor β (TGF-β) receptor after ligand binding) bind each other, and then bind and activate a target promoter. The other two papers describe a similar association between Notch and Smad1...