Charles R. Vinson, Ph.D.
My group is using genomic assays to study regulated gene expression, focusing on the C/EBP family of transcription factors (TF) that bind sequence-specific DNA containing methylated cytosines (5mC) in CG dinucleotides. The C/EBP family of TFs binds in the methylated regions of the genome and we are focusing on understanding how the methylated regions of the genome communicate with the unmethylated regions to activate gene expression. In parallel, we are using Agilent microarrays containing thousands of DNA features to explore sequence-specific DNA binding of TFs. We can methylate the arrays and examine the consequences on DNA binding.
1) transcription factors, 2) coiled-coil, 3) CG methylation, 4) DNA binding
Gene Regulation and Function: The bZIP Proteins
The regulation of gene expression underlies all cellular processes, including cancer. We are developing new gene-based protein methods to regulate genes, including (1) dominant-negatives (DNs) that inhibit the DNA binding of endogenous transcription factors, resulting in modulation of gene expression, and (2) gain-of-function genes that bind new DNA sequences, resulting in new gene expression. We have developed dominant-negatives to the dimeric B-ZIP (CREB, PAR, AP-1, and C/EBP) and B-HLH-ZIP (USF, Myc, and Mi) transcription factors. These dominant-negatives contain the dimerization domain of the transcription factor and an acidic protein sequence that replaces the basic region. The dominant-negatives heterodimerize with the endogenous transcription factors and prevent DNA binding. We are studying in detail the structural rules that regulate leucine zipper dimerization specificity and sequence-specific DNA binding.
Our recent work suggests that intracellular regulation of magnesium has profound effects on the sequence-specific DNA binding of B-ZIP proteins and highlights the possibility that magnesium may be an intracellular second messenger, similar to its larger cousin, calcium. We have expressed a dominant-negative that inhibits both the C/EBP and JUN family of transcription factors in fat tissue. The resulting mouse is ?fatless? and has severe diabetes. Using the new microarray technology, we are characterizing the genes that are misregulated. We are starting a project to examine the blood serum from these mice to identify missing peptides as possible hormones secreted from fat. This could have profound implications for the regulation of energy homeostasis. We are expressing these DNs in an inducible manner in transgenic mice to generate new phenotypes and identify transcriptional targets. Preliminary results obtained in collaboration with others indicate that expression of a dominant-negative to Jun (A-Fos) inhibits tumor formation. We have also placed these DNs into adenoviral vectors. We have shown that expression of A-Fos potentiates killing of the chemotherapeutic resistant cell lines. We are extending these studies to determine if expression of A-Fos selectively kills cancer cells.
Selected Recent Publications
Carboxylation of cytosine (5caC) in the CG dinucleotide in the E-box motif (CGCAG|GTG) increases binding of the Tcf3|Ascl1 helix-loop-helix heterodimer 10-fold.Biochem. Biophys. Res. Commun. 449: 248-55, 2014. [ Journal Article ]
- Genome Res. 24: 1209-23, 2014. [ Journal Article ]
Epigenetic and genetic inactivation of tyrosyl-DNA-phosphodiesterase 1 (TDP1) in human lung cancer cells from the NCI-60 panel.DNA Repair (Amst.). 13: 41648, 2014. [ Journal Article ]
- Genes Dev. 27: 251-60, 2013. [ Journal Article ]
C/EBP maintains chromatin accessibility in liver and facilitates glucocorticoid receptor recruitment to steroid response elements.EMBO J. 32: 1568-83, 2013. [ Journal Article ]
Dr. Charles Vinson received his Ph.D. from the University of Virginia studying Drosophila developmental genetics with Dr. Paul Adler. He subsequently carried out postdoctoral work at the Carnegie Institution of Washington in Baltimore, MD, with Dr. Steven McKnight, and joined the NCI as a tenure track fellow in 1991.
|Nima Assad||Postbaccalaureate Fellow|
|Sreejana Ray Ph.D.||Postdoctoral Fellow (Visiting)|
|Desiree Tillo Ph.D.||Postdoctoral Fellow (Visiting)|