posted on 2012-11-02, 00:00authored bySang Jin Kim, Jonghwa Jin, Young Joo Kim, Youngsoo Kim, Hyeong Gon Yu
To identify proteins that are involved in the molecular
mechanisms
of oxygen-induced retinopathy (OIR), a well-established model of blinding
ischemic retinopathy, we quantitatively analyzed the retinal proteome
in a mouse model of OIR. OIR was induced by exposing C57BL/6 mice
on postnatal day 7 (P7) to 75% hyperoxia for 5 days, followed by 5
days in room air. Retinas from mice on P12 and P17, the hyperoxic
and hypoxic phases, respectively, and control groups were examined
using isobaric tags for relative and absolute quantitation (iTRAQ)
and nano-LC-ESI-MS/MS. In total, 1422 retinal proteins were identified:
699 from the iTRAQ experiment and 1074 by nano-LC-ESI-MS/MS. Compared
with control retinas in the iTRAQ study, OIR retinas upregulated and
downregulated 21 and 17 proteins, respectively, in P17 retinas and
25 and 14 proteins, respectively, in P12 retinas. Of the differentially
expressed proteins, the retinal expression of crystallin proteins,
Müller cell-associated proteins, neurodegeneration-associated
proteins, and angiogenesis-associated proteins, such as 150-kDa oxygen-regulated
protein (ORP150), were analyzed. ORP150 colocalized to the neovascular
tufts, and knockdown of ORP150 by siRNA decreased the levels of secreted
VEGF in cultured retinal pigment epithelial cells. Moreover, intravitreal
administration of siRNA targeting ORP150 significantly reduced the
retinal neovascularization in OIR. In conclusion, our proteomic discovery
method, coupled with targeted approaches, revealed many proteins that
were differentially regulated in the mouse model of OIR. These proteins,
including ORP150, are potential novel therapeutic targets for the
treatment of proliferative ischemic retinopathy.