Ronald G. Gregg, PhD
Professor and Chairman
Phone Number:
Chairman's Office: 502-852-5217
502-852-4808; Lab 852-4687
Fax: 502-852-4112
Address: 319 Abraham Flexner Way, HSC-A, Room 616 Louisville, KY 40292 (40202 for Express Mail)
Ph.D., 1983, The University of Queensland, Australia
DNA Core
Research Interests
Synaptogenesis and development in the retina
Laboratory Personnel
Elizabeth Hudson email Elizabeth
Tom Ray email Tom
The long term goal of my research is to understand the molecular events that underlie the formation of one of the synaptic layers, the outer plexiform layer (OPL), in the retina. This synapse connects the photoreceptors that collect light and convert it into an electrical signal, to the second order neurons, bipolar and horizontal cells. Early in development the pre- and post-synaptic neurons make contact and begin to form a synapse. This initial contact triggers a series of events that results in a synapse of extraordinary complexity. Three dendrites from post-synaptic neurons invaginate into the axon terminal of the presynaptic cell, which is the photoreceptor in this case. We have discovered a mutant mouse that fails to undergo normal maturation of the synapse and results in night blindness. This model is being used to determine what signals are involved in the maturation of this important synapse.
In a second project, we are studying a mouse line, called nob, that has another form of congenital stationary night blindness. The cause of the disease in this mouse is a mutation in a novel protein called nyctalopin. The goal of this project is to determine how mutations in this protein result in a failure of signal transmission between photoreceptors and depolarizing bipolar cells.
A third project is a collaboration with Dr. Brian Link at the medical College of Wisconsin and Dr. John Dowling at Harvard University, to clone genes involved in retinal development and function in zebrafish. We use positional cloning to identify the genes with the long term goal of building a pathway of genes that are required for the formation of the retina.
To accomplish the goals of these various projects we use knockout mice, transgenic mice and zebrafish as well as a broad array of molecular biological and immunohistochemical techniques.
Selected Publications
Gregg RG, Kamermans M, Klooster J, Lukasiewicz PD, Peachey NS, Vessey KA, McCall MA.(2007. Nyctalopin expression in retinal bipolar cells restores visual function in a mouse model of complete X-linked congenital stationary night blindness. J Neurophysiol. 2007 Nov. 98(5):3023-33.
Palmer, C.A., Hollis, D.M., Watts, R.A., Houck, L.D., McCall, M.A., Gregg, R.G., Feldhoff, P.W., Feldhoff, R.C., Arnold, S.J. (2007). Plethodontid modulating factor, a hypervariable salamander courtship pheromone in the three-finger protein superfamily. FEBS J. 274:2300-2310.
Demas, J., Sagdullaev, B.T., Green, E., Jaubert-Miazza, L., McCall, M.A., Gregg, R.G., Wong, R.O., Guido, W. (2006). Failure to Maintain Eye-Specific Segregation in nob, a Mutant with Abnormally Patterned Retinal Activity. Neuron. 50:247-59.
Schroeter, E.H., Wong, R.O.L., Gregg R.G. (2006). In vivo development of retinal bipolar cell axonal terminals visualized in nyx::MYFP transgenic zebrafish. Visual Neuroscience, 23, 833–843.
Marmorstein, L.Y., Wu, J., McLaughlin, P., Yocom, J., Karl, M.O., Neussert, R., Wimmers, S., Stanton, J.B., Gregg, R.G., Strauss, O., Peachey, N.S., Marmorstein, A.D. (2006). The Light Peak of the Electroretinogram Is Dependent on Voltage-gated Calcium Channels and Antagonized by Bestrophin (Best-1). J. Gen. Physiol. 127:577-89.
Chang, B., Heckenlively, J.R., Bayley, P.R., Brecha, N.C., Davisson, M.T., Hawes, N.L., Hirano, A.A., Hurd, R.E., Ikeda, A., Johnson, B.A., McCall, M.A., Morgans, C.W., Nusinowitz, S., Peachey, N.S., Rice, D.S., Vessey, K.A. and Gregg, R.G. (2006). The nob2 mouse, a null mutation in Cacna1f: Anatomical and functional abnormalities in the outer retina and their consequences on ganglion cell visual responses. Visual Neuroscience 23:11-24.
Semina, E.V., Bosenko, D.V., Zinkevich, N.A., Soules, K.A., Halloran, M.C., Vihtelic, T.C., Willer, G.B., Gregg, R.G., Link, B.A. (2006) Mutations in laminin alpha 1 result in complex ocular phenotypes in zebrafish. Developmental Biology. Dev. Biol. 299, 63-77
Palmer, C.A., Watts, R.A., Gregg, R.G., McCall, M.A., Houck, L.D., Highton, R., Arnold, S.J. (2005). Lineage-Specific Differences in Evolutionary Mode in a Salamander Courtship Pheromone. Mol Biol Evol. 22:2243-2256.
Willer, G.B., Lee, V.M., Gregg, R.G., Link, B.A. (2005) Analysis of the zebrafish perplexed mutation reveals tissue specific roles for de novo pyrimidine synthesis during development.Genetics. 170:1827-37.
Liem, E.B., Lin, C.-M., Suleman, M-I., Doufas, A.G., Gregg, R.G., Veauthier, J.M., Loyd,G., Sessler, D.I. (2004) Anesthetic requirement is increased in redheads. (2004). Anesthesiology 101:279-83.
Arikkath,J., Chen,C.C., Ahern,C., Allamand,V., Flanagan,J.D., Coronado,R., Gregg,R.G., and Campbell,K.P. (2003). Gamma 1 subunit interactions within the skeletal muscle L-type voltage-gated calcium channels. J. Biol. Chem. 278, 1212-1219.
Ball,S.L., Pardue,M.T., McCall,M.A., Gregg,R.G., and Peachey,N.S. (2003). Immunohistochemical analysis of the outer plexiform layer in the nob mouse shows no abnormalities. Vis. Neurosci. 20, 267-272.
Gregg,R.G., Willer,G.B., Fadool,J.M., Dowling,J.E., and Link,B.A. (2003). Positional cloning of the young mutation identifies an essential role for the Brahma chromatin remodeling complex in mediating retinal cell differentiation. Proc. Natl. Acad. Sci. U. S. A 100, 6535-6540.
Gregg,R.G., Mukhopadhyay,S., Candille,S.I., Ball,S.L., Pardue,M.T., McCall,M.A., and Peachey,N.S. (2003). Identification of the gene and the mutation responsible for the mouse nob phenotype. Invest Ophthalmol. Vis. Sci. 44, 378-384.
Morris,C.A., Mervis,C.B., Hobart,H.H., Gregg,R.G., Bertrand,J., Ensing,G.J., Sommer,A., Moore,C.A., Hopkin,R.J., Spallone,P.A., Keating,M.T., Osborne,L., Kimberley,K.W., and Stock,A.D. (2003). GTF2I hemizygosity implicated in mental retardation in Williams syndrome: genotype-phenotype analysis of five families with deletions in the Williams syndrome region. Am. J. Med. Genet. 123A, 45-59.
Ball,S.L., Powers,P.A., Shin,H.S., Morgans,C.W., Peachey,N.S., and Gregg,R.G. (2002). Role of the beta(2) subunit of voltage-dependent calcium channels in the retinal outer plexiform layer. Invest Ophthalmol. Vis. Sci. 43, 1595-1603.
Ball,S.L. and Gregg,R.G. (2002). Using mutant mice to study the role of voltage-gated calcium channels in the retina. Adv. Exp. Med. Biol. 514, 439-450.
McCall,M.A., Lukasiewicz,P.D., Gregg,R.G., and Peachey,N.S. (2002). Elimination of the rho1 subunit abolishes GABA(C) receptor expression and alters visual processing in the mouse retina. J. Neurosci. 22, 4163-4174.
Read,D.S., McCall,M.A., and Gregg,R.G. (2002). Absence of voltage-dependent calcium channels delays photoreceptor degeneration in rd mice. Exp. Eye Res. 75, 415-420.
