The objectives of our proposal are twofold: a) to investigate the mechanism of c-kit receptor activation/function and b) to determine the molecular basis of the pleiotropic functions of c-kit, i.e. to elucidate the mechanism of the control of expression of the c-kit gene. The proto-oncogene c-kit is the normal cellular homolog of the oncogene v- kit of the HZ4 - feline sarcoma virus (Besmer et al., 1986) and encodes a transmembrane tyrosine protein kinase receptor. c-kit has been determined to be allelic with the dominant white spotting locus (W) of the mouse. Mutations at the W locus affect various aspects of hematopoiesis and the proliferation and/or migration of primordial germ cells and melanoblasts during development. The recent analysis of several dominant E mutations revealed that they are dominant negative mutations providing clues about the mechanism of kit mediated signal transduction. We will use an in vitro mutagenesis approach to further define the mechanism of activation of the c-kit tyrosine kinase receptor and of the P80gag-kit transforming protein. A most interesting aspect of the c-kit/W receptor system is its pleiotropy. c-kit function is the result of a combination of factors, namely, availability of ligand, the expression of the c-kit receptor and a functioning downstream signaling pathway. An important concern of our proposal is to further our understanding of the mechanism of the control of c-kit expression at the level of transcription and post transcriptional processing. Tissue specific regulatory sequences in c-kit will be identified by investigating transcription start sites, determining DNaseI hypersensitive sites, determining the transcription rates, by deletion mapping of the 5' flanking region of the c-kit gene with receptor gene constructs and by performing binding experiments to identify cell specific nuclear transacting factors. We will also attempt to create a mutation in a tissue specific promoter element of c-kit in the mouse germ line by use of homologous recombination technology and embryonic stem cells.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
2R37CA032926-07
Application #
3482267
Study Section
Virology Study Section (VR)
Project Start
1983-05-01
Project End
1995-12-31
Budget Start
1991-01-01
Budget End
1991-12-31
Support Year
7
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Sloan-Kettering Institute for Cancer Research
Department
Type
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10065
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Berrozpe, G; Timokhina, I; Yukl, S et al. (1999) The W(sh), W(57), and Ph Kit expression mutations define tissue-specific control elements located between -23 and -154 kb upstream of Kit. Blood 94:2658-66
Timokhina, I; Kissel, H; Stella, G et al. (1998) Kit signaling through PI 3-kinase and Src kinase pathways: an essential role for Rac1 and JNK activation in mast cell proliferation. EMBO J 17:6250-62
Vosseller, K; Stella, G; Yee, N S et al. (1997) c-kit receptor signaling through its phosphatidylinositide-3'-kinase-binding site and protein kinase C: role in mast cell enhancement of degranulation, adhesion, and membrane ruffling. Mol Biol Cell 8:909-22
Serve, H; Yee, N S; Stella, G et al. (1995) Differential roles of PI3-kinase and Kit tyrosine 821 in Kit receptor-mediated proliferation, survival and cell adhesion in mast cells. EMBO J 14:473-83
Yee, N S; Paek, I; Besmer, P (1994) Role of kit-ligand in proliferation and suppression of apoptosis in mast cells: basis for radiosensitivity of white spotting and steel mutant mice. J Exp Med 179:1777-87
Yee, N S; Hsiau, C W; Serve, H et al. (1994) Mechanism of down-regulation of c-kit receptor. Roles of receptor tyrosine kinase, phosphatidylinositol 3'-kinase, and protein kinase C. J Biol Chem 269:31991-8
Serve, H; Hsu, Y C; Besmer, P (1994) Tyrosine residue 719 of the c-kit receptor is essential for binding of the P85 subunit of phosphatidylinositol (PI) 3-kinase and for c-kit-associated PI 3-kinase activity in COS-1 cells. J Biol Chem 269:6026-30
Duttlinger, R; Manova, K; Chu, T Y et al. (1993) W-sash affects positive and negative elements controlling c-kit expression: ectopic c-kit expression at sites of kit-ligand expression affects melanogenesis. Development 118:705-17

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