Michael S. Krangel, PhD
The process of V(D)J recombination assembles T cell receptor (TCR) genes (α,β,γ,δ) from variable (V), diversity (D) and joining (J) gene segments during T cell development, and is essential for the formation of diverse antigen receptor repertoires on αβ and γδ T lymphocytes. We are interested in the molecular basis for developmentally regulated rearrangement and expression of murine TCR genes. One focus of our studies is the TCRα/δ locus, because it represents an intriguing model with two sets of gene segments that are differentially activated for recombination during T cell development. We are also studying the TCRβ locus, because this locus presents a model in which there is a developmental inactivation of V(D)J recombination associated with the process of allelic exclusion. V(D)J recombination depends on the ability of recombinase proteins RAG1 and RAG2 to recognize and generate double-strand breaks at recombination signal sequences that flank TCR gene segments. Our main focus has been on the role of chromatin structure in defining the portions of these loci that are accessible to the RAG recombinase and therefore active for V(D)J recombination, and on the mechanisms by which cis-regulatory elements within these loci (enhancers, promoters) function as developmental regulators of chromatin structure. Our primary approach has been to manipulate cis-acting elements within these loci by gene targeting, and to study the effects of these manipulations on locus chromatin structure and recombination events in developing thymocytes in vivo. An important outcome of this work has been our demonstration that enhancer- and promoter-directed transcription through recombination signal sequences can displace and covalently modify nucleosomes to provide accessibility for RAG binding and V(D)J recombination.
Recent work in our laboratory and elsewhere has highlighted additional properties of antigen receptor loci that likely to play important roles in developmental regulation. One area of interest is subnuclear positioning. We have used three-dimensional fluorescence in situ hybridization (3D-FISH) to show that TCRβ alleles interact stochastically and at high frequency with the nuclear lamina and with foci of pericentromeric heterochromatin, and that these interactions are inhibitory to V(D)J recombination. We suspect that these inhibitory interactions help to promote allelic exclusion by diminishing the likelihood of simultaneous V to DJ recombination on both alleles. Current work is aimed at developing a better understanding of how the TCRβ locus interacts with the nuclear lamina and the mechanism by which this interaction impacts recombination events.
A second area of interest is locus conformation. It is now appreciated that recombination events at antigen receptor loci depend on locus conformational changes that bring into proximity gene segments that may be widely separated in the linear DNA sequence. Conformational states can be defined using 3D-FISH or a chemical crosslinking approach called chromosome conformation capture (3C). Recent studies indicate that developmental changes in locus conformation contribute to allelic exclusion at the TCRβ locus and mediate a transition from TCRδ to TCRα rearrangement at the TCRα/δ locus. Current work aims to address at a molecular level how locus conformational states are maintained and modified during T cell development and how these changes impact long-distance transactions including enhancer-promoter communication and V(D)J recombination.
Education and Training
- Ph.D., Harvard University , 1982
Selected Grants and Awards
- Advanced Immunobiology Traning Program for Surgeons
- Control of TCR Delta and TCR Alpha Rearrangement
- Organization and Function of Cellular Structure
- Basic Immunology Training Program
- Center for Molecular & Cellular Studies of Ped Disease
- Training Program in Inflammatory and Immunological Diseases
- Control of TCR V Beta Rearrangement & Allelic Exclusion
- The role of BATF in allergic inflammation and anti-helminth immunity
- Orphan Nuclear Receptor in Thymocyte Differentiation
- Structure And Function Of I-309 And Other Chemokines
- Control Of Tcr * And Trc * Gene Rearrangement
- Control Of Tcr Delta And Tcr Alpha Rearrangement
- Human Gamma Delta T Cell Receptor
- Human Ganna Delta T Cell Receptor
Zhao, Lijuan, Richard L. Frock, Zhou Du, Jiazhi Hu, Liang Chen, Michael S. Krangel, and Frederick W. Alt. “Orientation-specific RAG activity in chromosomal loop domains contributes to Tcrd V(D)J recombination during T cell development..” J Exp Med 213, no. 9 (August 22, 2016): 1921–36. https://doi.org/10.1084/jem.20160670.
Thornton, Tina M., Pilar Delgado, Liang Chen, Beatriz Salas, Dimitry Krementsov, Miriam Fernandez, Santiago Vernia, et al. “Inactivation of nuclear GSK3β by Ser(389) phosphorylation promotes lymphocyte fitness during DNA double-strand break response..” Nat Commun 7 (January 29, 2016). https://doi.org/10.1038/ncomms10553.
Hao, Bingtao, Abani Kanta Naik, Akiko Watanabe, Hirokazu Tanaka, Liang Chen, Hunter W. Richards, Motonari Kondo, et al. “An anti-silencer- and SATB1-dependent chromatin hub regulates Rag1 and Rag2 gene expression during thymocyte development..” J Exp Med 212, no. 5 (May 4, 2015): 809–24. https://doi.org/10.1084/jem.20142207.
Majumder, Kinjal, Olivia I. Koues, Elizabeth A. W. Chan, Katherine E. Kyle, Julie E. Horowitz, Katherine Yang-Iott, Craig H. Bassing, Ichiro Taniuchi, Michael S. Krangel, and Eugene M. Oltz. “Lineage-specific compaction of Tcrb requires a chromatin barrier to protect the function of a long-range tethering element..” J Exp Med 212, no. 1 (January 12, 2015): 107–20. https://doi.org/10.1084/jem.20141479.
Boudil, A., I. R. Matei, H. Y. Shih, G. Bogdanoski, J. S. Yuan, S. G. Chang, B. Montpellier, et al. “IL-7 coordinates proliferation, differentiation and Tcra recombination during thymocyte β-selection.” Nature Immunology 16, no. 4 (January 1, 2015): 397–405. https://doi.org/10.1038/ni.3122.
Tubbs, Anthony T., Yair Dorsett, Elizabeth Chan, Beth Helmink, Baeck-Seung Lee, Putzer Hung, Rosmy George, et al. “KAP-1 promotes resection of broken DNA ends not protected by γ-H2AX and 53BP1 in G₁-phase lymphocytes..” Mol Cell Biol 34, no. 15 (August 2014): 2811–21. https://doi.org/10.1128/MCB.00441-14.