Humoral immunity is dependent on the expression of immunoglobulin (Ig) to fend off pathogenic challenges. The humoral immune system has evolved to produce Ig with a broad repertoire of binding specificities. Class switch recombination (CSR) is used to attain diversity of Ig effector function and tissue localization. The murine IgH constant region locus is organized: 5'-V(D)J-C?-Cd-C?3-C?1-C?2b-C?2a-Ce-Ca-3'. CSR involves an intra-chromosomal deletional rearrangement that focuses on regions of repetitive switch (S) DNA located upstream of each CH gene (with the exception of Cd). The process of CSR can be thought of as composed of three phases including, initiation, S/S synapsis and resolution and repair. AID induced DNA lesions at S regions initiates the process. I propose to examine events leading to S/S synapsis, and discern chromatin modifications associated with transcription and DNA repair. Using the chromosome conformation capture technique (3C), my laboratory has newly investigated the long- range interactions between the 5 intronic enhancer (E?) located between the VH and CH genes and the 3'Ea enhancer located at the 3'-end of the IgH locus together with the various GLT promoters. We find that in B cells, the E? and 3'Ea enhancers are in close spatial proximity forming a unique chromosomal loop configuration. B cell activation leads to recruitment of the germline transcript (GLT) promoters to the E?: 3'Ea complex in a cytokine dependent fashion. This structure facilitates S/S synapsis since S? is proximal to E? and the downstream S region are co-recruited with the targeted GLT promoter to the E?: 3'Ea complex. We propose that GLT promoter association with the E?: 3'Ea complex creates an architectural scaffolding that promotes S/S synapsis during CSR and these interactions are dependent on the stabilizing influence of AID. Chromatin remodeling is an important regulatory mechanism controlling the accessibility of S DNA to AID. We have defined histone modifications differentially found in the S and C regions. Our studies indicate chromatin accessibility is correlated with increased histone acetylation and H3K4me3 at the S regions whereas reduced accessibility is associated with hypoAc and the H3K36me3 mark downstream of the S region. We will study the causual relationship between accessibility and these histone modifications. NARRATIVE: Humoral immunity is dependent on the expression of immunoglobulin (Ig) to fend off pathogenic challenges. The humoral immune system has evolved to produce Ig with a broad repertoire of binding specificities. We study the molecular processes by which new types of Ig are expressed.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI052400-08
Application #
8073595
Study Section
Cellular and Molecular Immunology - A Study Section (CMIA)
Program Officer
Nasseri, M Faraz
Project Start
2002-04-01
Project End
2013-05-31
Budget Start
2011-06-01
Budget End
2012-05-31
Support Year
8
Fiscal Year
2011
Total Cost
$438,510
Indirect Cost
Name
University of Illinois at Chicago
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
098987217
City
Chicago
State
IL
Country
United States
Zip Code
60612
Feldman, Scott; Wuerffel, Robert; Achour, Ikbel et al. (2017) 53BP1 Contributes to Igh Locus Chromatin Topology during Class Switch Recombination. J Immunol 198:2434-2444
Montefiori, Lindsey; Wuerffel, Robert; Roqueiro, Damian et al. (2016) Extremely Long-Range Chromatin Loops Link Topological Domains to Facilitate a Diverse Antibody Repertoire. Cell Rep 14:896-906
Feldman, Scott; Achour, Ikbel; Wuerffel, Robert et al. (2015) Constraints contributed by chromatin looping limit recombination targeting during Ig class switch recombination. J Immunol 194:2380-9
G├╝rsoy, Gamze; Xu, Yun; Kenter, Amy L et al. (2014) Spatial confinement is a major determinant of the folding landscape of human chromosomes. Nucleic Acids Res 42:8223-30
Kumar, Satyendra; Wuerffel, Robert; Achour, Ikbel et al. (2013) Flexible ordering of antibody class switch and V(D)J joining during B-cell ontogeny. Genes Dev 27:2439-44
Grigera, Fernando; Bellacosa, Alfonso; Kenter, Amy L (2013) Complex relationship between mismatch repair proteins and MBD4 during immunoglobulin class switch recombination. PLoS One 8:e78370
Kenter, Amy L; Feldman, Scott; Wuerffel, Robert et al. (2012) Three-dimensional architecture of the IgH locus facilitates class switch recombination. Ann N Y Acad Sci 1267:86-94
Kenter, Amy L (2012) AID targeting is dependent on RNA polymerase II pausing. Semin Immunol 24:281-6
Bhattacharya, Palash; Wuerffel, Robert; Kenter, Amy L (2010) Switch region identity plays an important role in Ig class switch recombination. J Immunol 184:6242-8
Wang, Lili; Wuerffel, Robert; Feldman, Scott et al. (2009) S region sequence, RNA polymerase II, and histone modifications create chromatin accessibility during class switch recombination. J Exp Med 206:1817-30

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