This revised version of the grant application is a proposal to continue studies of human Damage DNA Binding Protein (DDB). In previous studies, the applicant has shown DDB to be a heterodimer of p127 and p48 which has roughly the same damage preference as E. coli UvrA protein. In addition, missense mutations in p48 exist in - and only in - a subset of Xeroderma pigmentosum group E patients (XP-E Ddb-) whose protein lacks activity. Purified normal protein can correct the XP repair defect only when injected into Ddb- cells. In response to DNA damage, p48 but not p127 expression is increased. Finally, recent observations by Dr. Linn and others show that DDB interacts with several cellular and viral transcription transactivating proteins. Dr. Linn now proposes to explore the role(s) of the individual DDB subunits in DNA repair and/or transcription pattern changes following exposures to DNA damaging agents. In particular, he proposes to identify cellular components with which p127 and p48 interact. To accomplish this goal, he proposes to construct trans-hybrid mice lacking either p48 or p127 (or cell lines only if the mice are unviable). He will overexpress each subunit individually in insect cells to make antibodies and/or affinity columns to determine which protein(s) the subunits interact with. In addition to antibodies or DDB subunits as affinity column ligands, lectins specific for the DDB glycosylation may be utilized. Dr. Linn will also do yeast two and three hybrid screens and promoter sequencing to accomplish the same goal. He has made green fluorescent protein hybrid proteins with p48 and p127 and these, along with antibodies, will be used to look at cellular localization of these proteins and co-localization with any putative DDB-interacting proteins in both normal and XP-E cells. All interactions will be studied as a function of DNA damage exposure and cell cycle. He will continue to explore the significance of the interaction of DDB with the transcription factors EBNA2 and E2F1. Finally, he expects to obtain sequence data of the 5' un-translated region to look for motifs which could provide suggestions of functions for the peptides. The genome of S. pombe appears to code for a homologue of human p127 but not of p48. Moreover, while extracts of S. pombe do not contain DDB activity, such activity appears upon addition of human p48 to the extracts. Dr. Linn plans to use both genetic and biochemical analysis to find the molecular basis of this activity and the consequences of directed mutations in the putative p127 homologue.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM059424-02
Application #
6386493
Study Section
Biochemistry Study Section (BIO)
Program Officer
Wolfe, Paul B
Project Start
2000-06-01
Project End
2004-05-31
Budget Start
2001-06-01
Budget End
2002-05-31
Support Year
2
Fiscal Year
2001
Total Cost
$338,400
Indirect Cost
Name
University of California Berkeley
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
094878337
City
Berkeley
State
CA
Country
United States
Zip Code
94704
Itoh, Toshiki (2006) Xeroderma pigmentosum group E and DDB2, a smaller subunit of damage-specific DNA binding protein: proposed classification of xeroderma pigmentosum, Cockayne syndrome, and ultraviolet-sensitive syndrome. J Dermatol Sci 41:87-96
Itoh, Toshiki; Linn, Stuart (2005) The fate of p21CDKN1A in cells surviving UV-irradiation. DNA Repair (Amst) 4:1457-62
Itoh, Toshiki; Cado, Dragana; Kamide, Ryoichi et al. (2004) DDB2 gene disruption leads to skin tumors and resistance to apoptosis after exposure to ultraviolet light but not a chemical carcinogen. Proc Natl Acad Sci U S A 101:2052-7
Sancar, Aziz; Lindsey-Boltz, Laura A; Unsal-Kacmaz, Keziban et al. (2004) Molecular mechanisms of mammalian DNA repair and the DNA damage checkpoints. Annu Rev Biochem 73:39-85
Nichols, Anne F; Itoh, Toshiki; Zolezzi, Francesca et al. (2003) Basal transcriptional regulation of human damage-specific DNA-binding protein genes DDB1 and DDB2 by Sp1, E2F, N-myc and NF1 elements. Nucleic Acids Res 31:562-9
Itoh, Toshiki; O'Shea, Cristin; Linn, Stuart (2003) Impaired regulation of tumor suppressor p53 caused by mutations in the xeroderma pigmentosum DDB2 gene: mutual regulatory interactions between p48(DDB2) and p53. Mol Cell Biol 23:7540-53
Asahara, Hitomi; Li, Ying; Fuss, Jill et al. (2003) Stimulation of human DNA polymerase epsilon by MDM2. Nucleic Acids Res 31:2451-9
Zolezzi, Francesca; Fuss, Jill; Uzawa, Satoru et al. (2002) Characterization of a Schizosaccharomyces pombe strain deleted for a sequence homologue of the human damaged DNA binding 1 (DDB1) gene. J Biol Chem 277:41183-91
Itoh, T; Nichols, A; Linn, S (2001) Abnormal regulation of DDB2 gene expression in xeroderma pigmentosum group E strains. Oncogene 20:7041-50
Itoh, T; Linn, S (2001) XP43TO, previously classified as xeroderma pigmentosum Group E, should be reclassified as xeroderma pigmentosum variant. J Invest Dermatol 117:1672-4