Members of the Notch/LIN-12/GLP-1 family of transmembrane receptors are believed to play a central role in development by regulating cell-fate decisions in invertebrates. The applicant has isolated several genes encoding Notch receptors and Notch ligands from rat, and has been studying their expression and function to address the molecular mechanism of Notch signaling during mammalian development. Notch is associated with malignancies, suggesting a role for maintaining an undetermined state during normal development, and Notch is also involved in human disorders of stroke and dementia (CADASIL and Alzheimer's disease), suggesting a role outside of development as well. Experiments proposed are based on the applicant's previous findings, and are logical extensions designed to answer a number of basic questions concerning Notch function. They will determine if Notch functions as a dimer or monomer, and if ligand activation of Notch involves ligand dimerization. They also will explore how Notch cell surface expression is regulated and investigate the hypothesis that Notch is cleaved and transported to the nucleus following ligand binding. In contrast to what has been reported for the invertebrate systems, they made the surprising observation that the mammalian ligands are not equal in their ability to activate the different Notch receptors. Based on these observations, they have designed experiments to identify sequences present in the ligands and receptors that account for the observed ligand specificity. In addition, they will explore the production and use of soluble forms of Notch ligands to study Notch signaling. They found that Notch signaling leads to activation of both CBF1-dependent and CBF1-independent pathways. Preliminary data indicate that the CBF1-dependent pathway positively regulates the expression of Notch. They will investigate the molecular mechanisms underlying this positive feedback system. They will also examine the possibility of reciprocal signaling in the ligand-expressing cell following ligand-receptor interactions. Together the experiments proposed in this grant will provide new information on the structure/function requirements of Notch-ligand interactions and thereby extend our present understanding of mammalian Notch signaling.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS031885-08
Application #
6343843
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Program Officer
Leblanc, Gabrielle G
Project Start
1994-01-01
Project End
2002-12-31
Budget Start
2001-01-01
Budget End
2001-12-31
Support Year
8
Fiscal Year
2001
Total Cost
$266,309
Indirect Cost
Name
University of California Los Angeles
Department
Biochemistry
Type
Schools of Medicine
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
D'Souza, Brendan; Meloty-Kapella, Laurence; Weinmaster, Gerry (2010) Canonical and non-canonical Notch ligands. Curr Top Dev Biol 92:73-129
Bozkulak, Esra Cagavi; Weinmaster, Gerry (2009) Selective use of ADAM10 and ADAM17 in activation of Notch1 signaling. Mol Cell Biol 29:5679-95
Nichols, James T; Miyamoto, Alison; Weinmaster, Gerry (2007) Notch signaling--constantly on the move. Traffic 8:959-69
Nichols, James T; Miyamoto, Alison; Olsen, Samantha L et al. (2007) DSL ligand endocytosis physically dissociates Notch1 heterodimers before activating proteolysis can occur. J Cell Biol 176:445-58
Miyamoto, Alison; Lau, Rhiana; Hein, Patrick W et al. (2006) Microfibrillar proteins MAGP-1 and MAGP-2 induce Notch1 extracellular domain dissociation and receptor activation. J Biol Chem 281:10089-97
Yang, Liang-Tung; Nichols, James T; Yao, Christine et al. (2005) Fringe glycosyltransferases differentially modulate Notch1 proteolysis induced by Delta1 and Jagged1. Mol Biol Cell 16:927-42
Nehring, Leslie C; Miyamoto, Alison; Hein, Patrick W et al. (2005) The extracellular matrix protein MAGP-2 interacts with Jagged1 and induces its shedding from the cell surface. J Biol Chem 280:20349-55
Ladi, Ena; Nichols, James T; Ge, Weihong et al. (2005) The divergent DSL ligand Dll3 does not activate Notch signaling but cell autonomously attenuates signaling induced by other DSL ligands. J Cell Biol 170:983-92
Hicks, Carol; Ladi, Ena; Lindsell, Claire et al. (2002) A secreted Delta1-Fc fusion protein functions both as an activator and inhibitor of Notch1 signaling. J Neurosci Res 68:655-67
Zhang, J; Chen, H; Weinmaster, G et al. (2001) Epstein-Barr virus BamHi-a rightward transcript-encoded RPMS protein interacts with the CBF1-associated corepressor CIR to negatively regulate the activity of EBNA2 and NotchIC. J Virol 75:2946-56

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