May 2006
Volume 47, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2006
Sara and Phosphatidylinositiol–3â⑬â,,¢–Phosphate in Disc Morphogenesis and Membrane Trafficking in Mammalian Photoreceptors
Author Affiliations & Notes
  • J.–Z. Chuang
    Ophthalmology, Weill, New, NY
  • T.–Y. Yeh
    Ophthalmology, Weill, New, NY
  • C.–H. Sung
    Ophthalmology, Weill, New, NY
  • Footnotes
    Commercial Relationships  J. Chuang, None; T. Yeh, None; C. Sung, None.
  • Footnotes
    Support  NIH grant EY11307, RPB, and Steinbach Research Foundation
Investigative Ophthalmology & Visual Science May 2006, Vol.47, 2843. doi:
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      J.–Z. Chuang, T.–Y. Yeh, C.–H. Sung; Sara and Phosphatidylinositiol–3â⑬â,,¢–Phosphate in Disc Morphogenesis and Membrane Trafficking in Mammalian Photoreceptors . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2843.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : In addition to its long–recognized role as a receptor for signal transduction, rhodopsin is now known to play an important structural role in ROS morphogenesis. How rhodopsin participates in ROS morphogenesis is poorly understood. We have isolated a FYVE domain–containing protein SARA (Smad Anchor for Receptor Activation) as a rhodopsin C–terminus interacting protein. The FYVE domain of SARA binds specifically to phosphatidylinositiol–3’–phosphate (PI3P), a product of phosphatidylinositiol–3’–kinase (PI3–kinase). The purpose of this study is to unravel the function relevance of SARA–rhodopsin interaction.

Methods: : Immunohistochemistry was carried out to determine the localization of SARA and PI3–kinase. In vivo retinal transfection was carried out to deliver either the SARA–siRNA or the FYVE domain of SARA. The transfected retinas were examined histologically and immunocytochemically.

Results: : SARA is highly abundant on the vesicles/tubules and sites immediately adjacent to the nascent disc membranes in the outer segment portions of axonemes in rodent rod photoreceptors. Function perturbation of SARA by RNA interference or FYVE domain overexpression in mammalian retinas in vivo leads to defects in outer segment targeting of rhodopsin and photoreceptor disc morphogenesis, and retinal atrophy. The coincidental distribution of PI3–kinase and fusion machinery components with SARA at the base of rod outer segment supports the model that newly synthesized disc membranes are formed by the fusion of vesicles.

Conclusions: : Our results, collectively, suggest that SARA and PI3P are critically involved in the membrane targeting of rhodopsin as well as the disc morphogenesis. Finally, our results open discussion for a model explaining the rod disc formation and renewal.

Keywords: photoreceptors • protein structure/function 
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