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, using higher-order chromatin structure, 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, 35:1-7, Summer 2007
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 Postioning 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 46kb" Molecular and Cellular Biology, 25:3220-3231, Winter 2005
Xiang, Y., and Garrard, W. T., "The Downstream Transcriptional Enhancer, Ed, Positively Regulates Mouse Igk Gene Expression and Somatic Hypermutation" J. Immunol, 180:6725-6732, Spring 2008
Widlak, P. and Garrard, W.T., "Roles of the Major Apoptotic Nuclease-DNA Fragmentation Factor-in Biology and Disease" Cell. Mol. Life Sciences, 66:263-274, Winter 2009
SIGNIFICANT PUBLICATIONS
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 k Locus" Immunity, 24:405-415, Spring 2006
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" Proc. Natl. Acad. Sci. USA, 95:8461-8466, Summer 1998
Cockerill, P.N., and Garrard, W.T., "Chromosomal Loop Anchorage of the Kappa Immunoglobulin Gene Occurs Next to the Enhancer in a Region Containing Topisomerase II Sites" Cell, 44:273-282, Spring 1986
Brekke, K. M., and Garrard, W.T., "Assembly and Analysis of the Mouse Kappa Gene Sequence" Immunogenetics, 56:490-505, Winter 2004
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" 2005, 94:1078-1087, Winter 2005
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