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Geoffrey Kapler

Geoffrey Kapler, Ph.D.

Professor
Chair
Department of Molecular and Cellular Medicine
Member of the GSBS Faculty

Room 440 Reynolds Medical Building / Lab Room 455
College Station, Texas 77843
Phone: 979-847-8690
Fax: 979-847-9481
Email: gkapler@medicine.tamhsc.edu

Education and Post-Graduate Training

Dr. Kapler received his B.S. in Biology from the University of Connecticut in 1979 and his Ph.D. in Genetics from Harvard University in 1989, working with Stephen Beverley. He did his postdoctoral research with the 2009 Nobel Laureate in Medicine, Elizabeth Blackburn, at the University of California, San Francisco. He joined the faculty at Texas A&M in 1994. Dr. Kapler is also a Member of Biochemistry and Biophysics and served as the chair of the Interdisciplinary Program in Genetics. In 2007 he was named Associate Department Head. In 2010 he was named Interim Departmental Chair. He has taught courses in medical genetics, yeast genetics, the cell cycle and chromosome biology.

Research Interests

Current research in chromosome biology is focused on understanding how trans-acting factors regulate replication initiation and the DNA damage checkpoint response. Work with the model eukaryote, Tetrahymena thermophila, has established new paradigms in the field. For example, recognition of the ribosomal DNA (rDNA) replication origin by the evolutionarily conserved, multi-subunit origin recognition complex (ORC) is mediated by a novel integral RNA subunit. This molecule, designated 26T RNA, corresponds to the 3’ end of 26S ribosomal RNA, and undergoes Watson-Crick base pairing with regulatory sequences at the rDNA origin. While 26T RNA is a component of all ORC complexes, it does not target ORC to other replication origins. This distinction may form the basis for the selective amplification of rDNA minichromosomes during development. Another rDNA binding factor, TIF1, prevents early firing of this replication origin. TIF1 mutants fail to trigger the DNA damage checkpoint response and exhibit gross genome instability, suggesting a more global role in chromosome homeostasis.

Selected Publications

Donti, T.R., Datta, S., Sandoval, P.Y., and Kapler, G.M. (2009) Differential targeting of Tetrahymena ORC to ribosomal DNA and non-rDNA replication origins. EMBO J. 28(3): 223-233.

Mohammad, M.M., Smith, A.G., Donti, T.R., and Kapler, G.M. (2007) Tetrahymena ORC contains a ribosomal RNA fragment that participates in rDNA origin recognition. EMBO Journal. 26,5048-5060.

Yakisich, J.S., and Kapler, G.M. (2006) Deletion of the Tetrahymena thermophila rDNA replication fork barrier region disrupts macronuclear rDNA excision and creates a fragile site in the micronuclear genome. Nucleic Acids Res. 34, 620-634.

Yakisich, J.S., Sandoval, P.Y., Morrison, T.L., and Kapler, G.M. (2006) TIF1 activates the intra-S phase checkpoint response in the diploid micronucleus and amitotic polyploid macronucleus of Tetrahymena. Molecular Biology of the Cell. 17,5185-5197.

Morrison, T.L., Yakisich, J.S., Cassidy-Hanley, D., and Kapler, G.M. (2005) TIF1 represses rDNA replication initiation, but promotes normal S phase progression and chromosome transmission in Tetrahymena. Mol. Biol. Cell. 16, 2624-2635.

Smith, J.J., Yakisich, J.S., Kapler, G.M., Cole, E.S., and Romero, D.P. (2004) A beta-tubulin mutation selectively uncouples nuclear division and cytokinesis in Tetrahymena thermophila. Eukaryot Cell. 3,1217-1226.