Notch signalling controls numerous developmental cell fate decisions through different combinations of ligands, receptors, signal transducers and effectors. On , Taelman and colleagues provide new insights into Notch signalling by describing the role played by the Notch effector Hairy-related transcription factor (XHRT1) in the development of the pronephros (embryonic kidney) in Xenopus. The researchers show that Notch activation is essential first for glomus (the site of blood filtration) and later for proximal tubule fates. They report that several basic helix-loop-helix Orange(bHLH-O) transcriptional repressors, such as XHRT1, which act as downstream mediators of Notch signalling, have distinct and restricted dynamic expression patterns in the developing pronephros and that their expression is regulated by Notch. XHRT1 in particular plays a role that is distinct from that of the other pronephric bHLH-O repressors in the early proximodistal patterning and glomus formation of the developing pronephros. Overall, these results highlight how Notch signalling uses different downstream effectors to send context-dependent messages during development.
