Notch signaling is an evolutionarily conserved intercellular signaling pathway that participates in critical processes throughout development, from embryogenesis to determination of adult stem cells. Activation of the Notch signaling pathway is also observed in a number of cancers. Many of the genes in this pathway were first identified in Drosophila; experiments in flies continue to contribute to understanding of the Notch signaling pathway, including its role in development and progression of cancer.
In human, there are 4 genes that encode NOTCH family transmembrane receptor proteins (NOTCH1-NOTCH4); there are 2 genes similar to the Drosophila Notch ligand Delta (DLL1 and DLL4) and 2 genes similar to the Drosophila Notch ligand Serrate (JAG1 and JAG2).
Much of the work in flies investigating the role of the Notch pathway in development of cancer has involved combining Notch signaling dysregulation with another cancer model (see 'Related Diseases' below). This is typically achieved by using targeted expression of an activated form of Notch (N) or overexpression of one of the Notch ligands, Delta (Dl) or Serrate (Ser). Frequently used are constructs of Notch lacking its extracellular domain; the functional intracellular domain (NICD) is constitutively active. Genes potentially involved in tumorigenesis have also been identified using these systems. For example, overexpression of Dl in the adult eye results in a mild overgrowth phenotype (often called a 'sensitized model"); mutations of interacting genes have been identified that enhance this phenotype and result in much increased, tumorous overgrowth.
The loss of N, Dl or other Notch pathway components in stem cells results in a population of differentiation-defective cells; this system has been used to investigate stem-cell-derived cancers, such as intestinal stem cell tumors and neural stem cell tumors. See human disease model reports 'cancer, intestinal stem cell models' (FBhh0000767) and 'cancer, neural stem cell dedifferentiation' (FBhh0001139).
[updated Feb. 2022 by FlyBase; FBrf0222196]
The Notch signaling pathway is commonly activated in cancer and its activation plays key roles in cancer development and progression. Inappropriate Notch signalling has been associated with virtually all aspects of cancer, including tumor cell growth, survival, apoptosis, angiogenesis, invasion and metastasis (Dominguez, 2014; pubmed:24780858, FBrf0225143).
Notch signaling is an intercellular signaling pathway that regulates interactions between physically adjacent cells through binding of Notch family receptors to their membrane-bound ligands on the adjacent cells. The NOTCH family of proteins are Type I single-pass transmembrane proteins that share structural characteristics including an extracellular domain consisting of multiple epidermal growth factor-like (EGF) repeats, and an intracellular domain consisting of multiple different domain types. [from Gene Cards, NOTCH1; 2018.03.15]
Moderate- to high-scoring ortholog of human NOTCH1, NOTCH2, NOTCH3, NOTCH4 (1 Drosophila to 4 human). Dmel\N shares 43-44% identity and 56-57% similarity with NOTCH1 and NOTCH2.
Moderate- to high-scoring ortholog of human DLL1 and DLL4 (1 Drosophila to 2 human); additional less closely related genes in human. Dmel\Dl shares 39% identity and 51-53% similarity with human DLL1 and DLL4.
Moderate-scoring ortholog of human JAG1 and JAG2 (1 Drosophila to 2 human). Dmel\Ser shares 33-35% identity and 46% similarity with the human genes.