Dll1

Delta-like protein 1 (DLL1) is a transmembrane ligand of the Notch signaling pathway. In humans, DLL1 is encoded by the DLL1 gene. The protein belongs to the Delta/Serrate/Lag2 family and features a Delta-like (DSL) domain and multiple epidermal growth factor (EGF)-like repeats that anchor it in the cell membrane and mediate receptor interaction.

DLL1 functions as a ligand for Notch receptors (Notch1–Notch4) on adjacent cells. Binding induces proteolytic cleavages that release the Notch intracellular domain, which translocates to the nucleus to regulate target gene transcription through the CSL/RBPJ pathway. This Notch signaling modulates cell fate, differentiation, and tissue patterning, playing a key role in processes such as lateral inhibition and developmental segmentation.

Expression of DLL1 occurs in the developing embryo, with notable involvement in neural development, somite formation, and various aspects of vascular and organ development. In vertebrate models, DLL1 is essential for proper somitogenesis; loss of DLL1 function can disrupt segmentation and lead to embryonic abnormalities or lethality.

Clinical and research relevance varies with context. Altered DLL1 expression or Notch signaling involving DLL1 has been observed in certain cancers and developmental disorders, though the effects are tissue-specific and depend on the broader signaling environment. DLL1 remains an active area of study for understanding Notch pathway modulation and its roles in development and disease.