Nansi Jo Colley, PhD
Professor
600 Highland Ave
Madison, WI 53792-0001
| Appointments: | |
| Degrees: | B.S. 1975, Western Michigan University
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| Fellowships: | Postdoctoral Fellowship, 1983-86, U.C. Los Angeles
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| Research: | The Molecular Genetics of Protein Trafficking and Targeting in Drosophila We are taking a genomics approach to identify novel loci involved in photoreceptor cell function in Drosophila melanogaster. One area of emphasis is dissecting the molecular basis of signaling in protein trafficking and targeting. We are specifically focused on the mechanisms that underlie rhodopsin transport through the secretory pathway in the photoreceptor cells. The major rhodopsin in Drosophila is called Rh1 and it displays 22% amino acid identity with human rhodopsin. In both humans and flies, during biosynthesis, rhodopsin, as well as the other components of phototransduction are transported through the secretory pathway, to their final destination for vision. We have previously shown that several mutations in Rh1 result in defects in its transport through the secretory pathway leading to retinal degeneration. In fact, four mutations that we identified in Drosophila correspond to identical mutations that have been implicated in an inherited human retinal degeneration disorder called retinitis pigmentosa (RP). Studies that we are conducting in flies are providing insights for mechanisms of retinal degeneration in human retinal degeneration disease. A cross section of the photoreceptors in the Drospohila compound eye reveals that the rhabdomeres of the R1-6 photoreceptors are immunolabeled with an antibody directed to Rhodopsin (green). The nuclei are shown in blue (ToPro). In addition, the InsP3 receptor immunolocalizes to the endoplasmic reticulum in a perinuclear fashion as well as in a punctate pattern consistant with vesicular labeling (Texas red). Deletion of the only InsP3 receptor gene in the Drosophila genome eliminates the InsP3 receptor immunoreactivity and results in retinal degeneration, but phototransduction is unaffected. The other area of focus in the lab is on the role of calcium in phototransduction. We are utilizing a combined molecular, genetic, biochemical, electrophysiological, and cell biological approach to characterize a novel sodium/calcium-potassium exchanger (NCKX) expressed in the Drosophila photoreceptor cells. Exchangers play a crucial role in modulating intracellular calcium and in human and Drosophila photoreceptor cells. Nckx30C and Calx are expressed in the adult eye and brain of Drosophila.
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| Recent Publications: |
Retinal degeneration in the fly.
XPORT-Dependent Transport of TRP and Rhodopsin.
Evidence for light perception in a bioluminescent organ.
Calnexin is essential for rhodopsin maturation, Ca2+ regulation, and photoreceptor cell survival.
Potassium-dependent sodium-calcium exchange through the eye of the fly.
Expression of rhodopsin and arrestin during the light-dark cycle in Drosophila. |