The rod cell is highly polarized and compartmentalized in both morphology and function. A number of genetic disorders affecting the retina are manifested in the trafficking of the visual pigment rhodopsin and the morphogenesis and/or renewal of the rod outer segment (ROS). Our previous studies showed that rhodopsin's C-terminus is a hot spot for mutations associated with retinitis pigmentosa (RP) and it contains the addressing code for its ROS delivery. We also showed that cytoplasmic dynein-based motility is essential for the directional transport of rhodopsin within the inner segment of rod. In this application, we propose to investigate the machinery and mechanisms that move rhodopsin within other distinct cellular domains of rod and their involvement in ROS formation and maintenance.
In Aim1, we propose to identify molecules that capture, retain, navigate, and/or fuse rhodopsin-laden vesicles onto apical surfaces. This study will use the model of polarized MDCK epithelial cells, which have proven useful for studying the vectorial transport of rhodopsin.
Aim 2 will study the physiological relevance of the interaction between rhodopsin and the FYVE domain-containing protein SARA, a novel rhodopsin C-terminus interacting protein. It has been shown that the FYVEdomain specifically binds phosphatidylinositiol-3'-phosphate, and SARA is involved in protein trafficking and membrane fusion. Our ultrastructural analysis reveals a unique distribution of SARA on the vesicles/tubules near nascent disc membranes in the proximal portion of ROS axoneme. We plan to test how the perturbation of SARA in vivo might affect rhodopsin targeting and disc morphogenesis by employing transfected rodent retinas as a model system. Conversely, the phenotypes of rods transfected with RP mutant rhodopsins that fail to bind to SARA will also be examined.
In Aim3, we will identify the cellular components involved in the SARA-mediated membrane fusion pathwayin the ROS and test their importance in rhodopsin targeting and disc biogenesis in vivo. Successful achievement of the proposed specific aims will significantly further our insights into the molecular basis of the genesis and maintenance of the polarity of visual cells. These topics are a central interest in cell biology and vision research. Finally, these studies are highly relevant for our understanding of the etiology of various degenerative retinal diseases and have important implications for future rational therapies for the diseased retina.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY011307-15
Application #
7751236
Study Section
Biology and Diseases of the Posterior Eye Study Section (BDPE)
Program Officer
Mariani, Andrew P
Project Start
1996-01-31
Project End
2010-12-31
Budget Start
2010-01-01
Budget End
2010-12-31
Support Year
15
Fiscal Year
2010
Total Cost
$403,743
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
060217502
City
New York
State
NY
Country
United States
Zip Code
10065
Hsu, Kuo-Shun; Chuang, Jen-Zen; Sung, Ching-Hwa (2017) The Biology of Ciliary Dynamics. Cold Spring Harb Perspect Biol 9:
Mestres, Ivan; Sung, Ching-Hwa (2017) Nervous system development relies on endosomal trafficking. Neurogenesis (Austin) 4:e1316887
Wahl, Silke; Magupalli, Venkat Giri; Dembla, Mayur et al. (2016) The Disease Protein Tulp1 Is Essential for Periactive Zone Endocytosis in Photoreceptor Ribbon Synapses. J Neurosci 36:2473-93
Mestres, Iván; Chuang, Jen-Zen; Calegari, Federico et al. (2016) SARA regulates neuronal migration during neocortical development through L1 trafficking. Development 143:3143-53
Chou, Szu-Yi; Hsu, Kuo-Shun; Otsu, Wataru et al. (2016) CLIC4 regulates apical exocytosis and renal tube luminogenesis through retromer- and actin-mediated endocytic trafficking. Nat Commun 7:10412
Liu, Chenshu; Chuang, Jen-Zen; Sung, Ching-Hwa et al. (2015) A dynein independent role of Tctex-1 at the kinetochore. Cell Cycle 14:1379-88
Hsu, Ya-Chu; Chuang, Jen-Zen; Sung, Ching-Hwa (2015) Light regulates the ciliary protein transport and outer segment disc renewal of mammalian photoreceptors. Dev Cell 32:731-42
Thuenauer, Roland; Hsu, Ya-Chu; Carvajal-Gonzalez, Jose Maria et al. (2014) Four-dimensional live imaging of apical biosynthetic trafficking reveals a post-Golgi sorting role of apical endosomal intermediates. Proc Natl Acad Sci U S A 111:4127-32
Yeh, Celine; Li, Aiqun; Chuang, Jen-Zen et al. (2013) IGF-1 activates a cilium-localized noncanonical G?? signaling pathway that regulates cell-cycle progression. Dev Cell 26:358-68
Sung, Ching-Hwa; Leroux, Michel R (2013) The roles of evolutionarily conserved functional modules in cilia-related trafficking. Nat Cell Biol 15:1387-97

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