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Robert A. Sclafani, PhD

Professor

Ph.D., Columbia University, 1981

Contact Information:

Phone: (303) 724-3271​
E-mail: Robert.Sclafani@ucdenver.edu

 ​

Graduate Program Memberships

MSTP
BSP
H​uman Medical Genetics​
Cancer Biology​
Molecular Biology​

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The main area of focus of the laboratory is the regulation of the G1 to S phase transition of the cell cycle in yeast and human cells. Most cells coordinate growth and division in this phase of the cell cycle. Elucidation of the mechanisms of cell cycle control and cell commitment to DNA replication is important for determining the etiology of a number of diseases, especially cancer, in which the regulation is altered. Yeast (Saccharomyces cerevisiae), as a eukaryotic microorganism is an excellent model system to study the cell cycle because facile molecular and high-throughput genomic techniques can be used in combination with classical biochemical and genetic methods. We use molecular genetic high-throughput genomic analysis of cultured human cancer cells for our studies that are focused on exploiting the deregulation of the cell cycle that occurs in cancer cells as a target for chemoprevention and therapy.

Yeast: Our current studies focus on the regulation of the initiation of DNA replication in yeast. DDK (Dbf4-dependent kinase; also known as Cdc7/Dbf4) is a protein kinase that regulates the initiation of DNA replication during the somatic cell cycle. DDK is activated by binding the Dbf4 protein during the G1 to S phase transition (for a review, see Sclafani and Holzen, 2007). DDK phosphorylates the MCM complex, a multi-subunit DNA helicase found at origins of DNA replication, to initiate the S phase. Both DDK and CDK (cyclin-dependent kinase) protein kinases are needed for multiple steps that ultimately intersect to activate the MCM helicase and to load on DNA polymerases during initiation. Our structure-function studies of the MCM complex use the Archaeal MCM helicase as a structural model and yeast MCM as a functional, physiological model for replication (Fletcher et al., 2003; Leon et al., 2008). DDK also acts to regulate error-prone translesion synthesis by DNA polymerase , which is important for mutagenesis (Pessoa-Brandão and Sclafani, 2004). Rad53/Chk2 protein kinase also has a role in initiation of replication that is separate from its role in the replication checkpoint and involves changes in chromatin structure (Dohrmann and Sclafani, 2006; Holzen and Sclafani, 2010).

Humans: We are determining the mode of action of several compounds found in natural products that function in cancer chemoprevention (Grape Seed extract, silibinin, IP6, resveratrol). These compounds are known to prevent cancer in animal models and are not toxic to normal cells. We have shown that the cell cycle is frequently the target of these compounds resulting in G1 cell cycle arrest (Roy et al., 2007; 2009; Kaur et al., 2011). In contrast, the compound resveratrol that is found in red grape skins and wine activates the DNA damage checkpoint pathway and produces S phase arrest in cancer cells (Tyagi et al., 2005). These studies are in collaboration with Dr. Rajesh Agarwal of the University of Colorado School of Pharmacy.


​Current Lab Colleagues

 Results From Research : Selected site and subsites
PicturesFirst NameJob TittleEmailBio Page
JohnResearch AssociateJohn.Diller@UCDenver.edu  
JamesProfessional Research AssistantJames.Dutchik@UCDenver.edu  
RebeccaPostdoctoral FellowRebecca.Ferguson@UCDenver.edu  
TeresaVisiting FacultyTeresa.Holzen@UCDenver.edu  
CassidyGraduate StudentCassidy.Punt@UCDenver.edu  
ChristopherPostdoctoral FellowChristopher.Ramey@UCDenver.edu  
DanGraduate StudentDaniel.Rossbach@UCDenver.edu  
SunithaProfessional Research AssistantSunitha.Siriwardana@UCDenver.edu  

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Fletcher, R. J., B. E. Bishop, R. P. Leon, R. A. Sclafani, C. M. Ogata, and X. S. Chen. The structure and function of MCM from archaeal M. Thermoautotrophicum. Nature Struct Biol 10:160-167. (2003)

Pessoa-Brandão, L. and Sclafani, R.A. (2004) CDC7/DBF4 functions in the translesion synthesis branch of the RAD6 epistasis group in Saccharomyces cerevisiae Genetics 167:1597-1610 (2004)

Sclafani, R.A., Fletcher, R.J., Chen, X.S. (2004) “Two Heads are Better than One”-Regulation of DNA Replication by Hexameric Helicases. Genes and Dev. 18:2039-2045 (2004)

Tyagi, A.K, Singh, R.P., Agarwal, C., Siriwardana, S., Sclafani R.A. and Agarwal, R. Resveratrol causes Cdc2-tyr15 phosphorylation via the ATM/ATR-Chk1/2-Cdc25C pathway as a central mechanism for S phase arrest in human ovarian carcinoma Ovar-3 cells. Carcinogenesis 26: 1978-87 (2005)

Dohrmann, P. and Sclafani, R.A. Novel Role for Checkpoint Rad53 Protein Kinase in the Initiation of Chromosomal DNA Replication in S. cerevisiae. Genetics 174:87-99 (2006)

Sclafani, R.A. and Holzen, T.M. Cell Cycle Regulation of DNA Replication. Annual Rev. of Genetics 41:237-280 (2007).

Hoang, M., Leon, R., Pessoa-Brandao, L. , Raghuraman, M.K., Fangman, W.L., Sclafani, R.A. Structural changes in Mcm5 protein bypass Cdc7-Dbf4 function and reduce replication origin efficiency in S. cerevisiae. Mol Cell Biol 27: 7594-7602 (2007).

S. Roy, M. Kaur, C. Agarwal, M. Tecklenburg, R.A. Sclafani and R. Agarwal. p21 and p27 induction by silibinin is essential for its cell cycle arrest effect in prostate carcinoma cells. Molecular Cancer Therapeutics 6: 2696-2707 (2007). PMID: 17938263

Roy, S., Singh, R.P., Siriwardana, S., Agarwal, C., Sclafani, R.A. and Agarwal, R. Down-regulation of both p21/Cip1 and p27/Kip1 produces a more aggressive prostate cancer phenotype. Cell Cycle 7: 1828-1835 (2008). PMID: 18583941

Leon. R.P, Tecklenburg, M. and Sclafani, R.A. Functional conservation of -hairpin DNA binding domains in the Mcm protein of M. thermoautotrophicum and Mcm5 protein of S. cerevisiae. Genetics 179: 1757-1768 (2008). PMID: 18660534.

Roy, S., Gu, M., Ramasamy, K., Singh, R.P., Agarwal, C., Siriwardana, S., Sclafani, R.A. and Agarwal, R. p21/Cip1 and p27/Kip1 are Essential Molecular Targets of Inositol Hexaphosphate for Its Antitumor Efficacy against Prostate Cancer. Cancer Research 69: 1166-73 (2009)

Holzen, T.M. and Sclafani, R. A., and. Genetic interaction of RAD53 protein kinase with histones is important for DNA replication Cell Cycle, 9:4735-47 (2010)

Kaur, M. Tyagi, A., Singh, R.P., Sclafani, R.A., Agarwal, R. and Agarwal, C., Grape seed extract up-regulates p21 (Cip1) by redox-mediated activation of ERK1/2 and post-transcriptional mechanisms for its cell cycle arrest effect in colon carcinoma HT29 cells. Mol. Carcinogenesis, in press (2011)

Pubmed search for Sclafani RA


Former Sclafani Lab Members 1985-2009:

PhD students:
Robert E. Hollingsworth, Ph.D. 1985-1990 Director of Oncology at Medimmune, LLC, MD
Jin-Yuan (Jimmy) Su, Ph.D.1986-1991 Professor at National Ming University, Taiwan
Aimee (Brown) Jackson, Ph.D.1989-1994 Director of Drug Discovery, Regulus Therapeutics, CA
Paula Pahl, Ph.D.1988-1995 President, Denver Pen Women, CO
Peter Hovland, M.D., Ph.D.1989-1995-Colorado Retina Associates, Denver, CO
Yiqun (Gui) Shellman, Ph.D. 1993-1998-Associate Professor, Dermatology, University of Colorado
Guy Oshiro, Ph.D. 1994-1999 Scientific Application Developer, John McNeil & Co., Inc., CA
Bryn Grimison, Ph.D. 1996-2001 Research Scientist-Insmed, Inc., Boulder, CO
Luis Pessoa (Brandão), Ph.D. 2000-2006-Postdoctoral Fellow, Pediatrics, University of Colorado
Lora Wilson, Ph.D. 2000-2006-Postdoctoral Fellow, Medicine, University of Colorado
Ronald Leon, Ph.D. 2001-2007 Postdoctoral Fellow, University of Oregon, Portland, OR

Postdoctoral Fellows:
Margaret van Boldrick, Ph.D. 1986-1987 Madison, WI
Rachel Ostroff, Ph.D.1989-1993 Clinical Research Director-SomaLogic, Inc. Boulder, CO
Irene Schauer, M.D., Ph.D. 1992-1996 Assistant Professor, Medicine, University of Colorado
Anne Galbraith, Ph.D. 1995-1998 Associate Professor, University of Wisconsin
Marguerite (Dalton) Kosovsky, Ph.D. 1996-1998, Northborough MA
Maria (Daly) Todd, Ph.D.1997-2000 Associate Professor, Southwestern University, Texas
Taroh Satoh, M.D.2001-2003 Medical Oncologist, Kinki University, Japan
Paul Dohrmann, Ph.D.1994-2000 Research Associate, University of Colorado
Angela Pierce, Ph.D. 1998-2000 Research Associate, University of Colorado

M.S. students:
Lee A. Niswander, Ph.D. M.S.-1985 -HHMI Investigator and Professor, Pediatrics, University of Colorado
Carolina Gonzalez-Aller, M.S.-1986-Instructor, Idaho State University

Professional Research Assistants
Bruce Thalley, M.A. 1985-1987
Michael Klein, M.S., MBA 1987-1993 Co-founder and Principal, Percepta Associates, Inc., CA
Marianne Tecklenburg, 1994-2009 Retired