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FRISC: The Faculty Research Interests Science Comparator |
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Professor of Molecular Biology
Biological Chemistry
Genetics and
Development
Immunology
Integrative Biology
Office: (214) 648-1924
FAX: (214) 648-1909
Email: william.garrard@utsouthwestern.edu
Home Page: http://www.swmed.edu/home_pages/garrardlab/
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
genes we study include the mouse kappa immunoglobulin gene locus and the HIV-1
promoter. We are also studying 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 3.5 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. We are in the process of elucidating the functions of these
elements, in part using kappa Ig gene mini-loci with lox-P sequences flanking
the sites for their later deletion by Cre-recombinase. We believe that these
elements will individually specify regulation of V-J joining, allelic exclusion,
and high level transcription. Earlier we identified an evolutionarily conserved
class of sequences that anchor chromosomal loops, termed matrix
association regions (MARs). We have evidence that the kappa gene MAR acts
as to down-regulate premature rearrangement and up-regulate somatic
hypermutation.
Another area of interest is the
mechanism for generating nucleosome-free regions in gene promoters. Using a
Xenopus leavis oocyte- in vitro
chromatin assembly system, we have found that within the HIV 5’-LTR both Sp1
and NF k B transcription factors are required to create
a hypersensitive site resembling the in vivo chromatin structure of the integrated virus. Chromatin
remodeling requires ATP and occurs with polarity.
Finally, we are investigating how apoptosis is regulated at the
level of the nuclease activation and chromatin condensation. We are interested
in determining the apoptotic nucleases preference and pattern of attack of
repressed- and transcriptionally-active gene-specific regulatory and coding
regions in chromatin, in generating better expression vectors for high-level
production of the nuclease for X-ray crystallography, in mapping intra- and
inter-molecular interacting surfaces of the nuclease and its inhibitor using
protein footprinting and functional mutagenesis, and in generating mutant forms
more suitable for X-ray crystallography and chromatin research.
Selected Publications:
Widlak, P., Li, P., Wang, X., and Garrard, W. T. (2000)
Cleavage Preferences of the Apoptotic Endonuclease DFF40 (Caspase-activated
DNase or Nuclease) on Naked DNA and Chromatin Substrates. J. Biol. Chem. 275: 8226-8232.
Li, S., Hammer, R. E., George-Raizen, J.B., Meyers, K. C.,
and Garrard, W.T. (2000) High Level
Rearrangement and Expression of YAC-Based Mouse k
Immunoglobulin Transgenes Containing Distal Regions of the Contig. J.
Immunol. 164: 812-824.
Scheuermann, R. H., and Garrard,
W. T. (1999) MARs of Antigen Receptor and Co-Receptor Genes. In: Critical
Reviews in Eukaryotic Gene Expression , vol. 9, pp. 295-310, CRC Press, Inc.
Sathyanarayana, U. G., Freeman,
L. A., Lee, M.-S., and Garrard, W. T. (1999) RNA Polymerase-Specific Nucleosome
Disruption by Transcription in vivo. J.
Biol. Chem. 274: 16431-16436.
Yi, M.,Wu, P., Trevorrow, K.W.,
Claflin, L. and Garrard, W.T. (1999) Evidence that the Ig k
Gene MAR Regulates the Probability of Premature V-J Joining and Somatic
Hypermutation. J. Immunol . 162:
6029-6039.
Liu, X., Zou, H., Widlak, P.,
Garrard, W., and Wang, X. (1999) Activation of the Apoptotic Endonuclease DFF40
(Caspase-activated DNase or Nuclease): Oligomerization and Direct Interaction
with Histone H1. J. Biol. Chem. 274:
13836-13840.
Li, S., George-Raizen, J.B.,
Hammer, R.E., and Garrard, W.T. (1998) Accurate quantification of expression of
transgenes marked with restriction endonuclease site polymorphisms by RT-PCR. BioTechniques .
25: 558-562.
Hale, M. A., and Garrard, W.T.
(1998) A Targeted k Immunoglobulin Gene Containing a
Deletion of the Nuclear Matrix Association Region Exhibits Spontaneous
Hyper-Recombination in Pre-B Cells. Mol.
Immunol . 35: 609-620.
Liu, X., Li, P., Widlak, P., Zou,
H., Luo, X., Garrard, W.T., and Wang, X. (1998) The 40-kDa Subunit of DNA
Fragmentation Factor Induces DNA Fragmentation and Chromatin Condensation during
Apoptosis. Proc. Natl. Acad. Sci. USA
95: 8461-8466.
Qiu, P., Kupfer, K.C. and
Garrard, W.T. (1997) A Method for Genome Comparisons and Hybridization
Studies Using Known Megabase-scale DNA Sequences as a Reference. Genomics 43:307-315.
Widlak, P. Gaynor, R. and
Garrard, W.T. (1997) In Vitro Chromatin Assembly of the HIV-1 Promoter: ATP-Dependent
Polar Repositioning of Nucleosomes by Sp1 and NF k B.
J. Biol. Chem. 272:17654-17661.
Liang, C.-p. and Garrard, W.T.
(1997) Template Topology and Transcription: Chromatin Templates Relaxed by
Localized Linearization are Transcriptionally Active in Yeast, Mol.
Cell. Biol. 17:2825-2834.
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Last updated: 18 May 2001
Extraction Method: Expand using Medical Synonyms-
Eliminated words list: MedlinePlus List
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Database: Medline abstracts (1967 - Present)
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Results computed on: 6/9/2006