Nansi Colley

Research Description:
We are focused on the molecular genetic basis of protein trafficking, chaperone function, signal transduction and neurodegeneration/neuroprotection in the photoreceptor cells of the fruit fly, Drosophila melanogaster. Our goal is to identify the molecular components underlying protein folding, targeting and transport , as well as calcium modulation and neuroprotection. Phototransduction in Drosophila utilizes a G protein-coupled phospholipase-C-mediated signaling cascade that is regulated by calcium. Light stimulation of the receptor, rhodopsin, activates a heterotrimeric G protein of the Gq family which activates a phospholipase C encoded by the norpA gene. We are focused on the precise targeting and transport mechanisms that assemble the constituents of phototransduction. Drosophila photoreceptors contain a photosensitive organelle called the rhabdomere. Rhabdomeres are functionally equivalent to the vertebrate photoreceptor outer segments and contain the rhodopsin photopigments and the other components of the phototransduction cascade. During biosynthesis, the members of phototransduction are specifically targeted and transported to the rhabdomeres. Drosophila is an ideal model system for the study of the assembly of G protein-coupled signaling cascades. Our studies in the fruit fly make use of powerful molecular genetic techniques to identify novel folding, transport and transduction molecules, and we are able to examine the function of these molecules in vivo. The results obtained from our studies offer insights into the molecular basis of photoreceptor cell function and understanding the genetic basis of retinal degeneration and neuroprotection.

Representative Publications:
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Rosenbaum, E.E., Brehm, K. S., Vasiljevic, E., C.-H. Liu, R.C. Hardie and N. J. Colley (2011) XPORT Dependent Transport of TRP and Rhodopsin. Neuron. 72(4):602-15.

Colley, N. J. (2012) Retinal Degeneration in the Fly. Adv. Exp. Med. Biol. 723:407-14.

Rosenbaum, E.E., Brehm, K.S Vasiljevic, E., Gajeski, A., Colley, N.J. (2012) Drosophila GPI-MT2 is Required for the GPI Attachment and Surface Expression of Chaoptin. Visual Neuroscience. 29:143-156.

Weiss, S., E. Kohn, D. Dadon, B. Katz, M. Lebandiker, M. Kosloff, N. J. Colley and B. Minke. (2012). Compartmentalization and Ca2+ buffering are essential for prevention of light induced retinal degeneration. Journal of Neuroscience 32(42):14696–14708.

Colley N. J. (2010) Retinal Degeneration through the Eye of the Fly. In: Darlene A.Dartt, editor. Encyclopedia of the Eye, Vol 4. Oxford: Academic Press. pp.54-61.

Kraus, A., Jung. J., Groenendyk, J., Bedard, K., Krause, K.H., Dubois-Dauphin, M., Baldwin, T.A., Agellon, L.B., Dyck, J., Gosgnach, S., Rosenbaum, E.E., Korngut, L., Colley, N.J., Zochodne, D., Todd, K., and Michalak, M. (2010) Calnexin Deficiency Leads to Dysmyelination. JBC Vol. 285 pp. 18928–18938. (Recommended by Faculty of 1000 Biology, Malini Raghavan and Elise Jeffery: http://f1000biology.com/guardpages/evaluation/3122970/)

Tong, D., N.S. Rozas, T. H. Oakley, J. Mitchell, N. J. Colley and M. J. McFall-Ngai (2009) Evidence for light perception in a bioluminescent organ. PNAS. 106: 9836-41.

Rosenbaum, E. E., R. C. Hardie, and N. J. Colley (2006) Calnexin is essential for rhodopsin maturation, Ca2+ regulation, and photoreceptor cell survival. Neuron. 49 (2): 229-241. (Recommended by Faculty of 1000 Biology, Mark Fortini: http://www.f1000biology.com/article/id/1030794/evaluation)