Research Interests
My research is concerned with DNA replication, DNA repair, and DNA damage activation of cell cycle checkpoints in human cells. Regulation and coordination of these events are essential for the maintenance of genetic stability and protection against carcinogenesis. Major projects are focused on underlying mechanisms of bypass replication of DNA photoproducts (translesion synthesis and recombination repair) and inhibition of replicon initiation and DNA strand growth in human cells exposed to ultraviolet (UV) radiation. Collaborative research has expanded this focus to include (i) mutagenesis studies in human fibroblasts damaged by platinum-based chemotherapeutic drugs; (ii) mapping of functional origins of DNA replication in human cells; (iii) distribution of functional genetic elements (replication origin and nuclear matrix attachment sites) in early-replicating domains of the chromatin and the organization of these domains along human chromosomes; (iv) identification of proteins that interact with DNA polymerase eta during translesion synthesis of pyrimidine dimers in vitro and those factors involved in the recruitment of this enzyme to damaged sites during nuclear DNA replication in intact human cells; (v) evaluation of post-replication repair as a major protective pathway against the development of malignant melanoma.

Recent Accomplishments and Honors
In vitro replication assays, using human cell extracts and circular duplex DNA containing the SV40 origin of replication and a single site-specific DNA photoproduct, established that xeroderma pigmentosum variant (XP-V) fibroblasts are deficient in bypass replication of cyclobutane thymine dimers. This accomplishment was an important contribution to the field, leading to the discovery and characterization by other laboratories of DNA polymerase eta and the identification of mutations underlying the enhanced susceptibility of XP-V to UV-induced mutagenesis and carcinogenesis. Our initial studies were expanded to include analyses of the structure of DNA replication intermediates, the evaluation of translesion synthesis versus template switching (copy choice) as the primary mode of replication past thymine dimmers in vitro, and the effect of the position of the DNA lesion (either on the template for the leading or the lagging strand of nascent DNA) on the efficiency of bypass of DNA photoproducts.

Studies in collaboration with the W. Kaufmann laboratory demonstrated the dependence of the S checkpoint inhibition of replicon initiation on the activity of the ATR and Chk1 kinases in human cells exposed to low fluences of UV and the importance of cell cycle checkpoints in protecting XP-V fibroblasts from UV-induced chromatid-type aberrations. Complementation of expression of wild-type DNA polymerase eta in XP-V generated isogenic pairs of diploid human fibroblasts for studies of the biological role(s) of this enzyme in DNA damage tolerance following exposure to either physical or chemical carcinogens. For instance, a recent study in collaboration with the Chaney laboratory indicated that DNA polymerase eta is involved in accurate translesion synthesis of certain cisplatin-DNA adducts during nuclear DNA replication. These isogenic cells also represent valuable tools for ongoing studies on how this error-prone bypass polymerase is actively recruited to replicate accurately across DNA lesions, but kept from replicating undamaged DNA, considering that the replication fidelity of DNA polymerase eta is significantly lower than that exhibited by the normal replicative DNA polymerases.

Understanding the regulation and organization of DNA replication requires information on the chromosomal location and time of activation of replication origins during the S phase of the cell cycle. Our collaborative studies with the D. Kaufman group have led to the generation of a cosmid library of DNA sequences replicated early in the S phase of diploid human fibroblasts and the discovery of several new origins of replication. These efforts are now supporting a major functional genomic study, which is concerned with the distribution in the human genome of genetic elements that regulate DNA replication and/or modulate DNA organization within nuclear chromatin.

DNA polymerase eta is involved in the accurate replication of UV-damaged DNA, which minimizes UV-induced mutagenesis. With the help of the Borchers laboratory, we are using proteomic approaches to identify proteins that bind to DNA polymerase eta before or during translesion synthesis of thymine dimers. As these proteins might contribute to or regulate the function of DNA polymerase eta, this project promises to generate information relevant to solar carcinogenesis. In this regard, our laboratory is participating in a new initiative to bring several basic scientists, who are working on different aspects of DNA repair, replication, and checkpoint control in UV-damaged cells, together with clinical investigators, who are studying the pathogenesis of malignant melanoma. Such an inter-disciplinary effort is needed for reaching a better understanding of how several DNA metabolic pathways and cellular responses to DNA damage are coordinated in normal target cells (human melanocytes) and how these protective barriers might be compromised during cancer development. Another important component of this research will include computer scientists with experience in molecular modeling and generation of interactive maps.

Training
B.S. (1969), M.S. (1972, and Ph.D. (1976) - University of So Paulo, Brazil

Pre-doctoral research at the University of Texas at Austin (1972-1975)

Post-doctoral research at the University of North Carolina at Chapel Hill

Publications
Cohen SM, Hatada S, Brylawski BP, Smithies O, Kaufman DG, Cordeiro-Stone M: Complementation of replication origin function in mouse embryonic stem cells by human DNA sequences. Genomics 2004, in press.

Brylawski BP, Cohen SM, Horne H, Irani N, Cordeiro-Stone M, Kaufman, DG: Transition in replication timing in a 340-kb region of human chromosomal R-band 1p36.1. J Cell Biochem 2004; in press.

Nikiforov AA, Svetlova MP, Solovjeva LV, Oei SL, Ziegler M, Nikolaishvili-Feinberg N, Cordeiro-Stone M, Tomilin NV: [A study of dynamics of some postreplication DNA repair proteins in carcinogen-damaged mammalian cells]. Tsitologiia 2004;46:43-52.

Kaufmann WK, Heffernan TP, Beaulieu LM, Doherty S, Frank AR, Zhou Y, Bryant MF, Zhou T, Luche DD, Nikolaishvili-Feinberg N, Simpson DA, Cordeiro-Stone M: Caffeine and human DNA metabolism: the magic and the mystery. Mutat Res 2003;532:85-102.

Cohen SM, Brylawski BP, Cordeiro-Stone M, Kaufman DG: Same origins of DNA replication function on the active and inactive human X chromosomes. J Cell Biochem 2003;8:923-931.

Heffernan TP, Simpson DA, Frank AR, Heinloth AN, Paules RS, Cordeiro-Stone M, Kaufmann WK: An ATR- and Chk1-dependent S checkpoint inhibits replicon initiation following UVC-induced DNA damage. Mol Cell Biol 2002;22:8552-8561.

Cordeiro-Stone M, Nikolaishvili-Feinberg N: Asymmetry of DNA replication and translesion synthesis of UV-induced thymine dimers. Mutat Res 2002;510:91-106.

Cordeiro-Stone M, Frank A, Bryant M, Oguejiofor I, Hatch SB, McDaniels LD, Kaufmann WK: DNA damage responses protect xeroderma pigmentosum variant from UVC-induced clastogenesis. Carcinogenesis 2002;23:959-965.

Cohen SM, Brylawski BP, Cordeiro-Stone M, Kaufman DG: Mapping of an origin of DNA replication near the transcriptional promoter of the human HPRT gene. J Cell Biochem 2002;85:346-356.

Nikolaishvili-Feinberg N, Cordeiro-Stone M: Bypass replication in vitro of UV-induced photoproducts blocking leading or lagging strand synthesis. Biochemistry 2001;40:15215-15223.

Bullock SK, Kaufmann WK, Cordeiro-Stone M: Enhanced S phase delay and inhibition of replication of an undamaged shuttle vector in xeroderma pigmentosum variant. Carcinogenesis 2001;22:233-241.

Nikolaishvili-Feinberg N, Cordeiro-Stone M: Discrimination between translesion synthesis and template switching during bypass replication of thymine dimers in duplex DNA. J Biol Chem 2000;275:30943-30950.

Brylawski BP, Cohen SM, Cordeiro-Stone M, Schell MJ, Kaufman DG: On the relationship of matrix association and DNA replication. Critical ReviewsTM in Eukaryotic Gene Expression 2000;10;91-99.

Brylawski BP, Cohen SM, Longmire JL, Doggett NA, Cordeiro-Stone M, Kaufman DG: Construction of a cosmid library of DNA replicated early in the S phase of normal human fibroblasts. J Cell Biochem 2000;78:509-517.

Cordeiro-Stone M, Makhov AM, Zaritskaya LS, Griffith JD: Analysis of DNA replication forks encountering a pyrimidine dimer in the template to the leading strand. J Mol Biol 1999;289:1207-1218.

Cohen SM, Cobb ER, Cordeiro-Stone M, Kaufman DG: Identification of chromosomal bands replicating early in the S phase of normal human fibroblasts. Exp Cell Res 1998;245:321-329.

Kazantsev A, Bullock SK, Sancar A, Cordeiro-Stone M: Generation and characterization of an immortal cell line of xeroderma pigmentosum group E. Mutat Research-DNA Repair 1998;407:55-65.

Cordeiro-Stone M, Zaritskaya LS, Price LK, Kaufmann WK: Replication fork bypass of a pyrimidine dimer blocking leading strand DNA synthesis. J Biol Chem 1997;272:13945-13954.

E-mail: uncmcs@med.unc.edu
Telephone: (919) 966-1396
FAX: (919) 966-5046
Address: 620A Brinkhous-Bullitt Chapel Hill, NC
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