Sustained renewal of light-sensitive membranes, which comprise the rod outer segments (ROS) of retinal photoreceptors, is essential for their viability and for preservation of vision. Blinding eye diseases afflicting human populations are often caused by mutations that inactivate crucial components of the molecular machinery that regulates polarized membrane trafficking and ROS renewal in photoreceptor cells. In patients with retinitis pigmentosa, photoreceptor health is particularly compromised by the mutations in the C-terminal domain of rhodopsin. Our recent studies have revealed the existence of a sorting signal within this domain. This leads us to propose that the recognition of this signal initiates a cascade of molecular interactions that govern the targeted delivery of rhodopsin-carrying membranes to the ROS and associated morphogenic events. Using biochemical and cell biological approaches we have identified new candidates that regulate sequential steps in rhodopsin trafficking and ROS morphogenesis. Among them are the small GTPases of ARF, rab and rho families. We plan to study the role of these regulatory factors in rhodopsin trafficking and maintenance of photoreceptor polarity. We will delineate the interactions of rhodopsin with ARF GTPases and other regulatory proteins involved in polarized trafficking and photoreceptor membrane renewal. We will define the role in rhodopsin trafficking of rab11 and rad, small GTPases implicated by our preliminary results. To accomplish these goals, we will perturb membrane trafficking in healthy photoreceptors to model conditions found in patients with retinal degenerative diseases. We will modify, inactivate, or remove essential components of the sorting machinery, or introduce mutant proteins, and monitor their effects on membrane trafficking in vivo and in our established cell-free system in vitro. These studies will be complemented by morphological analysis of altered cells by confocal and electron microscopy. Our long-term goals are to better understand the molecular mechanisms by which mutations in rhodopsin and other photoreceptor genes trigger retinal degenerations. Ultimately, this knowledge will aid in the development of new strategies for treatment of retinal genetic disorders.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY012421-07
Application #
7213278
Study Section
Biology and Diseases of the Posterior Eye Study Section (BDPE)
Program Officer
Mariani, Andrew P
Project Start
1999-01-01
Project End
2010-03-31
Budget Start
2007-04-01
Budget End
2008-03-31
Support Year
7
Fiscal Year
2007
Total Cost
$364,137
Indirect Cost
Name
University of New Mexico
Department
Surgery
Type
Schools of Medicine
DUNS #
868853094
City
Albuquerque
State
NM
Country
United States
Zip Code
87131
Wang, Jing; Fresquez, Theresa; Kandachar, Vasundhara et al. (2017) The Arf GEF GBF1 and Arf4 synergize with the sensory receptor cargo, rhodopsin, to regulate ciliary membrane trafficking. J Cell Sci 130:3975-3987
Wang, Jing; Deretic, Dusanka (2015) The Arf and Rab11 effector FIP3 acts synergistically with ASAP1 to direct Rabin8 in ciliary receptor targeting. J Cell Sci 128:1375-85
Vetter, Melanie; Wang, Jing; Lorentzen, Esben et al. (2015) Novel topography of the Rab11-effector interaction network within a ciliary membrane targeting complex. Small GTPases 6:165-73
Wang, Jing; Deretic, Dusanka (2014) Molecular complexes that direct rhodopsin transport to primary cilia. Prog Retin Eye Res 38:1-19
Deretic, Dusanka (2013) Crosstalk of Arf and Rab GTPases en route to cilia. Small GTPases 4:70-7
Wang, Jing; Morita, Yoshiko; Mazelova, Jana et al. (2012) The Arf GAP ASAP1 provides a platform to regulate Arf4- and Rab11-Rab8-mediated ciliary receptor targeting. EMBO J 31:4057-71
Lu, Rong-Wen; Curcio, Christine A; Zhang, Youwen et al. (2012) Investigation of the hyper-reflective inner/outer segment band in optical coherence tomography of living frog retina. J Biomed Opt 17:060504
Deretic, Dusanka; Wang, Jing (2012) Molecular assemblies that control rhodopsin transport to the cilia. Vision Res 75:5-10
Ward, Heather H; Brown-Glaberman, Ursa; Wang, Jing et al. (2011) A conserved signal and GTPase complex are required for the ciliary transport of polycystin-1. Mol Biol Cell 22:3289-305
Mazelova, Jana; Astuto-Gribble, Lisa; Inoue, Hiroki et al. (2009) Ciliary targeting motif VxPx directs assembly of a trafficking module through Arf4. EMBO J 28:183-92

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