View Annual Report - Jules Stein Eye Institute

hui sun, PhD
Associate Professor of Physiology and Ophthalmology
Member of the Jules Stein Eye Institute
ReseaRch summaRy
Molecular Mechanism of
Vitamin A Transport for Vision;
Identification of New Therapeutic
Targets for Blinding Diseases
Dr. Sun’s laboratory studies the molecular mechanism
of vitamin A transport for vision and new therapeutic
targets for blinding diseases such as age-related
macular degeneration. Vitamin A deficiency is the
leading cause of blindness in third world countries, and
age-related macular degeneration is a leading cause of
blindness in the developed world. Vitamin A is essential
for vision because it is the precursor for the chromophore
of photoreceptor proteins and also plays critical
roles in eye development. Plasma retinol binding protein
(RBP) is the principal carrier of vitamin A in the blood
and is essential for mobilizing the hepatic vitamin A
store. Dr. Sun’s laboratory identified the long-sought
RBP receptor as a multitransmembrane protein of
previously unknown function. It functions simultaneously
as a membrane receptor and a membrane transporter
that mediates cellular uptake of vitamin A. The RBP/
RBP receptor system represents a rare example in
eukaryotic cells of a small molecule delivery system that
involves an extracellular carrier protein but does not
depend on endocytosis. Human genetic studies found
that the RBP receptor is essential for the formation of
the human eye and many other organs, consistent with
the critical role of vitamin A in embryonic development.
Dr. Sun’s laboratory is using a variety of techniques to
study this membrane transport system.
62 Faculty | Sun
Public Service
Ad hoc Reviewer, National Science Foundation,
National Eye Institute (United States), Health Research
Board (Ireland), and Medical Research Council
(United Kingdom)
Reviewer for many scientific journals
Research Grants
National Eye Institute: Molecular Mechanism of
Vitamin A Uptake for Vision, 9/30/07–8/31/12
Howard Hughes Medical Institute, 9/1/09–8/31/15
Research to Prevent Blindness Ophthalmic Research Award,
1/1/12–12/31/14