We study early events of lymphoid development, in particular gene rearrangement of the T cell receptor genes. Crosslinking of the Fc receptor on thymic precursors has been previosly found to block gene rearrangement and subsequently T cell development. We have now cloned thymic precursor cells and shown that the progeny of a single thymic precursor can be diverted into either the T cell lineage or natural killer cell lineage. We have previously identified a nuclear protein that binds flanking sequences on all rearrranging genes. We have purified the protein and are attempting to derive amino acid sequences from it. We have recently cloned a novel putative helicase that is specifically expressed in early thymic precursors. We are testing with the use of mutant expression vectors a role in gene rearrangement and T cell commitment. We have isolated genomic clones in order to study genomic structure and the promoter region of the lymphoid specific helicase. We are currently developing a targeted disruption of the helicase gene in mice in order to study a role for the helicase in lymphoid development. We are also studying the molecular mechanism of double-stranded DNA repair. The Ku-dimer is essential for gene rearrangement as well as DNA repair after radiation damage. We have tested the Ku86 and Ku70 peptides for protein-protein interaction in the yeast-two-hybrid system and are currently generating mutants. We have screened a Hela cell library for novel proteins interacting with the Ku86/Ku70 dimer. We are currently testing a number of isolated clones for specific interaction with the Ku-dimer to determine the role in the cellular response to radiation damage and double-stranded DNA break repair.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Intramural Research (Z01)
Project #
1Z01BC010014-01
Application #
2463814
Study Section
Special Emphasis Panel (LMI)
Project Start
Project End
Budget Start
Budget End
Support Year
1
Fiscal Year
1996
Total Cost
Indirect Cost
Name
National Cancer Institute Division of Basic Sciences
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Xi, Sichuan; Geiman, Theresa M; Briones, Victorino et al. (2009) Lsh participates in DNA methylation and silencing of stem cell genes. Stem Cells 27:2691-702
Zhu, Heming; Geiman, Theresa M; Xi, Sichuan et al. (2006) Lsh is involved in de novo methylation of DNA. EMBO J 25:335-45
Fan, Tao; Hagan, John P; Kozlov, Serguei V et al. (2005) Lsh controls silencing of the imprinted Cdkn1c gene. Development 132:635-44
Huang, Jiaqiang; Fan, Tao; Yan, Qingsheng et al. (2004) Lsh, an epigenetic guardian of repetitive elements. Nucleic Acids Res 32:5019-28
Yan, Qingsheng; Huang, Jiaqiang; Fan, Tao et al. (2003) Lsh, a modulator of CpG methylation, is crucial for normal histone methylation. EMBO J 22:5154-62
Muegge, Kathrin (2003) Modifications of histone cores and tails in V(D)J recombination. Genome Biol 4:211
Muegge, Kathrin; Young, Howard; Ruscetti, Francis et al. (2003) Epigenetic control during lymphoid development and immune responses: aberrant regulation, viruses, and cancer. Ann N Y Acad Sci 983:55-70
Fan, Tao; Yan, Qingsheng; Huang, Jiaqiang et al. (2003) Lsh-deficient murine embryonal fibroblasts show reduced proliferation with signs of abnormal mitosis. Cancer Res 63:4677-83
Geiman, T M; Muegge, K (2000) Lsh, an SNF2/helicase family member, is required for proliferation of mature T lymphocytes. Proc Natl Acad Sci U S A 97:4772-7
Lee, C K; Kim, K; Geiman, T M et al. (1999) Cloning thymic precursor cells: demonstration that individual pro-T1 cells have dual T-NK potential and individual pro-T2 cells have dual alphabeta-gammadelta T cell potential. Cell Immunol 191:139-44

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