Kuz and TACE can activate Notch independent of ligand.
A central mechanism in activation of the Notch signaling pathway is cleavage of the Notch receptor by ADAM metalloproteases. ADAMs also cleave Delta, the ligand for Notch, thereby downregulating Notch signals. Two ADAMs, Kuzbanian (Kuz) and TNF-alpha converting enzyme (TACE), are known to process both Delta and Notch, yet the role of these cleavages in signal propagation has remained controversial. Using an in vitro model, we show that Kuz regulates Notch signaling primarily by activating the receptor and has little overall effect on signaling via disabling Delta. We confirm that Kuz-dependent activation of Notch requires stimulation of Notch by Delta. However, over-expression of Kuz gives ligand-independent Notch activation. In contrast, TACE, which is elevated in expression in the developing Drosophila nervous system, can efficiently activate Notch in a ligand-independent manner. Altogether, these data demonstrate the potential for Kuz and TACE to participate in context- and mechanism-specific modes of Notch activation.
Delwig
A
A
Department of Anatomy and Neurobiology, University of Vermont, HSRF 426C, 149 Beaumont Ave., Burlington, VT 05405, USA.
Rand
M D
MD
D051722:ADAM Proteins / Q000235:genetics / Q000378:metabolism*; D000072198:ADAM17 Protein; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D019483:Disintegrins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D017344:Genes, Insect; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D009420:Nervous System / Q000254:growth & development / Q000378:metabolism; D034622:RNA Interference; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
D017931:DNA Primers; D019483:Disintegrins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008565:Membrane Proteins; C497759:N protein, Drosophila; D051880:Receptors, Notch; C064045:delta protein; D051722:ADAM Proteins; C100953:KUZ protein, Drosophila; D008666:Metalloendopeptidases; D000072198:ADAM17 Protein