NM23-H2 may play an indirect role in transcriptional activation of c-myc gene expression but does not cleave the nuclease hypersensitive element III[subscript 1]

Journal Article · Wed May 13 00:00:00 EDT 2009 · Mol. Cancer Ther.

DOI:https://doi.org/10.1158/1535-7163.MCT-08-1093· OSTI ID:1018555

Dexheimer, Thomas S; Carey, Steven S; Zuohe, Song; Gokhale, Vijay M; Hu, Xiaohui; Murata, Lauren B; Maes, Estelle M; Weichsel, Andrzej; Sun, Daekyu; Meuillet, Emmanuelle J; Montfort, William R; Hurley, Laurence H ^[1]

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1. Ariz

The formation of G-quadruplex structures within the nuclease hypersensitive element (NHE) III{sub 1} region of the c-myc promoter and the ability of these structures to repress c-myc transcription have been well established. However, just how these extremely stable DNA secondary structures are transformed to activate c-myc transcription is still unknown. NM23-H2/nucleoside diphosphate kinase B has been recognized as an activator of c-myc transcription via interactions with the NHE III{sub 1} region of the c-myc gene promoter. Through the use of RNA interference, we confirmed the transcriptional regulatory role of NM23-H2. In addition, we find that further purification of NM23-H2 results in loss of the previously identified DNA strand cleavage activity, but retention of its DNA binding activity. NM23-H2 binds to both single-stranded guanine- and cytosine-rich strands of the c-myc NHE III{sub 1} and, to a lesser extent, to a random single-stranded DNA template. However, it does not bind to or cleave the NHE III{sub 1} in duplex form. Significantly, potassium ions and compounds that stabilize the G-quadruplex and i-motif structures have an inhibitory effect on NM23-H2 DNA-binding activity. Mutation of Arg{sup 88} to Ala{sup 88} (R88A) reduced both DNA and nucleotide binding but had minimal effect on the NM23-H2 crystal structure. On the basis of these data and molecular modeling studies, we have proposed a stepwise trapping-out of the NHE III{sub 1} region in a single-stranded form, thus allowing single-stranded transcription factors to bind and activate c-myc transcription. Furthermore, this model provides a rationale for how the stabilization of the G-quadruplex or i-motif structures formed within the c-myc gene promoter region can inhibit NM23-H2 from activating c-myc gene expression.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: USDOE Office of Science (SC)
• OSTI ID: 1018555
• Journal Information: Mol. Cancer Ther., Vol. 8, Issue (5) ; 05, 2009; ISSN 1535-7163
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
74 ATOMIC AND MOLECULAR PHYSICS
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
CLEAVAGE
CRYSTAL STRUCTURE
DNA
GENES
GUANINE
MUTATIONS
NUCLEASES
NUCLEOTIDES
PHOSPHOTRANSFERASES
POTASSIUM IONS
PROMOTERS
PURIFICATION
RETENTION
RNA
SIMULATION
STABILIZATION
TRANSCRIPTION
TRANSCRIPTION FACTORS