Our goals are to understand the relationship between chromatin structure and the control of gene expression and differentiation in eukaryotes. We have selected to employ the powerful biological systems of cultured mouse cell lines that are arrested at different stages of B lymphocyte differentiation, embryonic stem cells, transgenic and knockout mice, and the yeast, Saccharomyces cerevisiae. The model gene we study the mouse kappa immunoglobulin gene locus. We have also studied the regulation of programmed cell death at the level of chromatin dynamics.
The mouse kappa immunoglobulin gene locus is serving as a paradigm for the role of higher order chromatin structure in specifying tissue specific transcriptional activation and recombination. We have cloned and mapped the entire locus, which spans more than 3.2 megabases, using YAC technology. Mapping the location of nuclease hypersensitive sites in chromatin as a function of B cell differentiation, we have identified several such sites that are pre-B- and B-cell-specific transcriptional silencers and enhancers. We are in the process of elucidating the functions of these elements, in part using YAC kappa Ig gene mini-loci with lox-P sequences flanking the sites for their later deletion by Cre-recombinase, and also the traditional knockout mice approach. We have evidence that these elements individually specify regulation of V-J joining, allelic exclusion, high level transcription, receptor revision and somatic hypermutation. Earlier we identified an evolutionarily conserved class of sequences that anchor chromosomal loops, termed matrix association regions; (MARs).
RESEARCH INTERESTS
Chromosome Structure
Transcriptional Regulation in Eukaryotes
Regulation of V-J joining
Apoptosis
RECENT PUBLICATIONS
Xiao, F., Widlak, P., and Garrard, W. T., "Engineered Apoptotic Nucleases for Chromatin Research." Nucleic Acids Research, doi: 10.1093/nar/gkm486:1-7, Summer 2007
Widlak, P. and Garrard, W. T., "Unique Features of the Apoptotic Endonuclease DFF40/CAD Relative to Micrococcal Nuclease as a Structural Probe for Chromatin" Biochemistry and Cell Biology, 84:405-410, Summer 2006
Liu, Z., Widlak, P., Zou, Y., Xiao, F., Oh, M., Li, S., Chang, M. Y., Shay, J. W., and Garrard, W. T., "A Recombination Silencer that Specifies Heterochromatin Positioning and Ikaros Association in the Immunoglobulin kappa Locus" Immunity, 24:405-415, Spring 2006
Widlak, P., Kalinowska, M., Parseghian, M. H., Lu, X., Hansen, J. C., and Garrard , W. T., "The Histone H1 C-terminal Domain Binds to the Apoptotic Nuclease, DNA Fragmentation Factor (DFF40/CAD) and Stimulates DNA Cleavage." Biochemistry, 44:7871-7878, Winter 2005
Liu, Z. and Garrard, W. T., "Long Range Interactions between Three Transcriptional Enhancers, Active Vk Gene Promoters and a 3? Boundary Sequence Spanning 46 kb" Molecular and Cellular Biology, 25:3220-3231, Winter 2005
SIGNIFICANT PUBLICATIONS
Liu, X., Li, P., Widlak, P., Zou, H., Luo, X., Garrard, W.T., and Wang, X., "The 40-kDa Subunit of DNA Fragmentation Factor Induces DNA Fragmentation and Chromatin Condensation during Apoptosis" Proceedings of the National Academy of Sciences USA, 95:8461-8466
Liu, Z., Widlak, P., Zou, Y., Xiao, F., Oh, M., Li, S., Chang, M. Y., Shay, J. W., and Garrard, W. T., "A Recombination Silencer that Specifies Heterochromatin Positioning and Ikaros Association in the Immunoglobulin kappa Locus" Immunity, 24:405-415, Spring 2006
Liu, Z. and Garrard, W. T., "Long Range Interactions between Three Transcriptional Enhancers, Active Vk Gene Promoters and a 3? Boundary Sequence Spanning 46 kb" Molecular and Cellular Biology, 25:3220-3231, Spring 2006
Brekke, K. M., and Garrard, W. T., "Assembly and Analysis of the Mouse Immunoglobulin Kappa Gene Sequence" Immunogenetics, 56:490-505, Winter 2004
Liu, X., Li, P., Widlak, P., Zou, H., Luo, X., Garrard, W.T., and Wang, X., "The 40-kDa Subunit of DNA Fragmentation Factor Induces DNA Fragmentation and Chromatin Condensation during Apoptosis" Proceedings of the National Academy of Sciences USA, 95:8461-8466, Summer 1998
Cockerill, P.N., and Garrard, W.T., "Chromosomal Loop Anchorage of the k Immunoglobulin Gene Occurs Next to the Enhancer in a Region Containing Topoisomerase II Sites" Cell, 44:273-282, Spring 1986
Point and right click (click and hold for Mac users) your mouse onand select "Save this link (or target) as..." option to save the file to your local computer.
and select "Save this link (or target) as..." option to save the file to your local computer.