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Pamela Geyer, PhD
Professor of Biochemistry and Obstetrics & GynecologyCarver College of MedicineUniversity of Iowa375 Newton Rd, 3135E MERFIowa City, IA 52242Phone: (319) 335-6953Lab Phone: (319) 335-7967Fax: (319) firstname.lastname@example.org
Eukaryotes contain thousands of genes whose unique patterns of expression establish distinct cellular identities. These processes require coordinate transcriptional regulation of hundreds of genes. Within the nucleus, genes reside within chromosomes that are arranged in the nucleus to facilitate gene expression. Emerging evidence suggests that nuclear organization of chromosomes is fundamental to transcription regulatory processes, as explified by observations that mutations in the nuclear envelop proteins, such as nuclear lamins, are associated with the human diseases of Emery-Dreifuss muscular dystrophy and the Hutchinson-Gilford progeria syndrome, associated with premature aging. It is believed that these diseases are caused by mis-expression of genes due to changes in nuclear positioning.
Within chromosomes, many clusters of co-expressed genes exist. These functional domains likely facilitate transcriptional regulation, as chromosomal rearrangements that disrupt this organization often influence levels of gene expression. Formation of independent regulatory domains may depend upon a specialized class of DNA elements, known as insulators. Insulators have been identified in most eukaryotic genomes, suggesting a conserved role in defining domains of gene function. Insulators play a critical role in many developmental processes, such as imprinting and mammalian dosage compensation and a loss of insulator function is associated with congenital forms of myotonic dystrophy.
Our laboratory is interested in understanding how chromosome organization impacts gene expression. To this end, we are taking molecular genetic and biochemical approaches to investigate chromosome organization in Drosophila melanogaster. We are engaged in three research areas. First, we are studying the role of nuclear envelope proteins, such as lamins, in gene expression in Drosophila. Second, we are examining the role of a chromatin insulator, known as the gypsy insulator, in defining domains of gene expression. Third, we are studying the process of transvection, where enhancers on one chromosome activate transcription of the paired, homologous promoter. These studies will provide insights into mechanisms of transcriptional regulation and its relationship to human disease.
Barton, L.J., Pinto,
B.S., Wallrath, L.L. and Geyer, P.K., (2013), The Drosophila nuclear lamina
protein Otefin is required for germline stem cell survival, Dev. Cell
A.A., He, B, Baxley, RM, Jiang, N, Hart, CM, Tan, K and Geyer, PK
(2012), Genome-wide studies of the multi-zinc finger Drosophila Suppressor of Hairy-wing protein in the ovary,
NA Research 40: 5415-31.
Thompson, M., Soshnev, A.A., Wu, J, Morris, J, Hsieh,
T.-S, Wu, C-t., Geyer, P.K. (2012), Restoration of Topoisomerase 2 function by
complementation of defective monomers in Drosophila, Genetics 192:
Geyer, P.K., Vitalini, M.W., and Wallrath, L.L. (2011) Nuclear organization: Taking a position on gene expression. Curr. Opin. in Cell Biology 23:354-9.
Baxley, R.M., Soshnev, A.A., Koryakov, D., Zhimulev, I. and Geyer, P.K.(2011) The role of the Suppressor of Hairy-wing insulator protein in Drosophila oogenesis, Developmental Biology 356:398 - 410.
Soshnev, A.A, Ishimoto, H., McAllister, B.F., Li, X., Wehling, M.D., Kitamoto, T. and Geyer, P.K. (2011) A conserved long non-coding RNA plays a role in sleep regulation in Drosophila, Genetics, in press.
Dialynas, G., Speese, S., Budnik, V., Geyer, P.K., and Wallrath, L.L. (2010) The role of Drosophila Lamin C in muscle function and gene expression. Development 137: 3067-77.
Schulze, S.R., Curio-Penny, B., Speese, S., Dialynas, G., Cryderman, D.E., McDonough, C.W., Nalbant, D., Petersen, M., Budnik, V., Geyer, P.K., Wallrath, L.L. (2009) A comparative study of Drosophila and human A-type lamins. PLoS One. Oct. 26; 4(10)e7564. Download reprint pdf
Soshnev, A.A., Li, X-G., Wehling, M.D., Geyer, P.K. (2008) Context differences reveal insulator and activator functions of a Su(Hw) binding region. PLoS Genetics, 15:e1000159. Download reprint pdf
Pinto, B.S., Wilmington, S.R., Wallrath, L.L., Geyer, P.K. (2008) Tissue-specific defects are caused by loss of the Drosophila MAN1 LEM domain protein. Genetics, 180:133-145. Download reprint pdf
Kuhn-Parnell E, Helou C, Marion D, Gilmore B, Parnell T, Wold M, Geyer P. (2008) Investigation of the properties of non-gypsy Su(Hw) binding sites. Genetics, 179:1263-1273. Download reprint pdf
Parnell, T.J., Kuhn, E.J., Gilmore, B.L., Helou, C., Wold, M.S. and Geyer, P.K. (2006) Identification of genomic sites that bind the Drosophila Suppressor of Hairy-wing protein. Mol. Cell. Biol. 26:5983-5993. Download reprint pdf
Wallrath, L.L., and Geyer, P.K. (2006) TFIIIC boxes in the genome. Cell 125:829-831. Download reprint pdf
Drapeau, M.D., Cyran, S.A., Viering, M.M., Geyer, P.J., and Long, A.D. (2006) A cis-regulatory sequence within the yellow locus of Drosophila melanogaster required for normal male mating success. Genetics 172:1009-1030. Download reprint pdf
Li, X.-G., and Geyer, P.K. (2005) Gene Silencing, in Encyclopedia of Science and Technology.
Schulze, S.R., Curio-Penny, B., Li, Y., Imani, R.A., Rydberg, L., Geyer, P.K., and Wallrath, L.F. (2005) Molecular genetic analysis of the nested Drosophila melanogaster Lamin C gene. Genetics 171:185-196. Download reprint pdf
Wallrath, L.L., Danzer, J.R., Yazgan, O. and P.K. Geyer (2004) Nuclear organization, chromatin structure and gene silencing, In Encyclopedia of Biological Chemistry (W.J. Lennarz & M.D. Lane, eds), Elsevier, Oxford, Vol 3: pp. 105-108.
Kuhn, E.J., Hart, C.M., and Geyer, P.K. (2004) Studies of the role of the Drosophila scs and scs' insulators in defining boundaries of a chromosome puff. Mol. Cell. Biol. 24(4):1470-1480. Download reprint pdf
Parnell, T.J., Grade, S.K., Geyer, P.K. and Wallrath, L.L. (2003) Position-effect variegation in human genetic disease, in Cooper D (Ed.), Encyclopedia of the Human Genome. John Wiley & Sons, Ltd, p. 642-646 (Volume 4).
Parnell, T.J., Viering, M.M., Skjesol, A., Helou, C., Kuhn, E.J., and Geyer, P.K. (2003) An endogenous suppressor of Hairy-wing insulator separates regulatory domains in Drosophila. Proc. Nat'l. Acad. Sci. 100:13436-13441. Download reprint pdf
Kuhn, E.J. and Geyer, P.K. (2003) Genomic insulators: connecting properties to mechanism. Curr. Opin. in Cell Biol. 15:259-265. Downlaod reprint pdf
Kuhn, E.J., Viering, M.M., Rhodes, K.M. and Geyer, P.K. (2003) A test of insulator interactions in Drosophila. EMBO J. 22:2463-2471. Download reprint pdf
Chen, J.-L., Huisinga, K.L., Viering, M.M., Ou, Sharon, Wu, C.-T., and Geyer, P.K. (2002) Enhancer action in trans is permitted throughout the Drosophila genome. Proc. Natl. Acad. Sci. 99:3723-3728. Download reprint pdf
Obstetrics & Gynecology