Delta-like protein 4 (DLL4) (DLL4)

Delta-like protein 4 (DLL4) is a type I transmembrane protein that serves as a primary ligand for Notch receptors, specifically Notch1 and Notch4, within the Notch signaling pathway [UniProt: Q9JI71]. In both murine and human systems, it is predominantly expressed in vascular endothelial cells, where it acts as a critical regulator of vascular sprouting by coordinating the selection of "tip" and "stalk" cells during angiogenesis [PubMed: 17110563]. Beyond its vascular functions, murine DLL4 is essential for the specification of T-cell fate from hematopoietic progenitors in the thymus [PubMed: 15155993]. In pathological contexts, DLL4 is frequently upregulated in tumor-associated vasculature, making it a significant therapeutic target; its inhibition leads to "unproductive angiogenesis," where tumors develop a dense but non-functional vascular network that fails to support tumor growth [PubMed: 17110564]. Clinical and preclinical agents targeting DLL4, such as demcizumab and navicixizumab, have demonstrated efficacy in reducing tumor burden and targeting cancer stem cells, though they are associated with specific toxicities like hypertension and cardiac stress due to the systemic role of Notch signaling [PubMed: 25538241, PubMed: 21810915].

Other names

Delta-like 4Delta-like ligand 4Drosophila Delta homolog 4Dll4

DLL4 acts as a ligand that binds to Notch receptors (primarily Notch1 and Notch4), initiating a signaling cascade that regulates vascular development and cell fate. Therapeutic antibodies block this interaction, leading to "unproductive angiogenesis" in tumors and inhibition of cancer stem cell maintenance [PubMed: 17110564].