The focus of this work is to define the regulatory mechanisms that govern the differential expression of myc-family genes. Myc-family oncoproteins (c-, N- and L-myc) are believed to function as regulators of normal development. Distinctive patterns and changes in expression of myc-family genes are correlated with critical developmental transitions in different cell lineages, suggesting that their differential expression may influence processes leading to cellular differentiation. The molecular mechanisms that govern the expression of myc-family genes are poorly understood. Nuclear run-on experiments indicate that transcriptional attenuation is an important mechanism in the regulation of myc-family gene expression with respect to tissue and developmental stage. The experiments outlined in this proposal are designed to (1) determine the mechanisms responsible for the tissue-specific and developmental stage-specific expression of the N-myc gene and (2) understand the physiological role of these regulatory mechanisms in normal development processes and in malignant transformation. The regulation of myc-family gene expression results from a complex regulatory strategy involving transcriptional initiation, attenuation and mRNA stability. In this proposal, we will focus primarily on the N-myc attenuator element because transcriptional attenuation appears to be the dominant mechanism regulating the tissue-specific and developmental stage-specific expression of the N-myc gene during mouse development. Regulatory sequences and factors that mediate attenuation will be identified by both biochemical and molecular genetic analysis. Candidate attenuator sequences identified by biochemical methods will be verified functionally in a transforming assay and gene-fusion experiments. Since myc gene expression studies using gene transfer into cultured cells and transgenic mice are subject to a number of artifacts, including chromosomal position effects and poor tissue-specific regulation, we will utilize gene targeting methods to mutate and analyze the attenuator sequence element in the endogenous N-myc gene. In situ sequence disruption will be performed first in a cell culture-based differentiation system and ultimately in the mouse germline. The biological impact of altered N-myc regulation will be examined. These studies will assess (1) the role of attenuation in the deregulation of myc expression in malignant transformation, (2) the significance of attenuation in the developmental expression of N-myc and (3) the significance of N-myc downregulation during cellular differentiation,

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD028317-02
Application #
3329906
Study Section
Mammalian Genetics Study Section (MGN)
Project Start
1991-09-01
Project End
1994-08-31
Budget Start
1992-09-01
Budget End
1993-08-31
Support Year
2
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Type
Schools of Medicine
DUNS #
009095365
City
Bronx
State
NY
Country
United States
Zip Code
10461
de Alboran, I M; O'Hagan, R C; Gartner, F et al. (2001) Analysis of C-MYC function in normal cells via conditional gene-targeted mutation. Immunity 14:45-55
Hemann, M T; Rudolph, K L; Strong, M A et al. (2001) Telomere dysfunction triggers developmentally regulated germ cell apoptosis. Mol Biol Cell 12:2023-30
Lee, K H; Rudolph, K L; Ju, Y J et al. (2001) Telomere dysfunction alters the chemotherapeutic profile of transformed cells. Proc Natl Acad Sci U S A 98:3381-6
O'Hagan, R C; Ohh, M; David, G et al. (2000) Myc-enhanced expression of Cul1 promotes ubiquitin-dependent proteolysis and cell cycle progression. Genes Dev 14:2185-91
Artandi, S E; DePinho, R A (2000) A critical role for telomeres in suppressing and facilitating carcinogenesis. Curr Opin Genet Dev 10:39-46
O'Hagan, R C; Schreiber-Agus, N; Chen, K et al. (2000) Gene-target recognition among members of the myc superfamily and implications for oncogenesis. Nat Genet 24:113-9
Bardeesy, N; Wong, K K; DePinho, R A et al. (2000) Animal models of melanoma: recent advances and future prospects. Adv Cancer Res 79:123-56
Wong, K K; Chang, S; Weiler, S R et al. (2000) Telomere dysfunction impairs DNA repair and enhances sensitivity to ionizing radiation. Nat Genet 26:85-8
Malynn, B A; de Alboran, I M; O'Hagan, R C et al. (2000) N-myc can functionally replace c-myc in murine development, cellular growth, and differentiation. Genes Dev 14:1390-9
Rudolph, K L; Chang, S; Millard, M et al. (2000) Inhibition of experimental liver cirrhosis in mice by telomerase gene delivery. Science 287:1253-8

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