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A. Thanos, Y. Morizane, G. Trichonas, X. Koufomichali, T. Papakostas, J. W. Miller, L. H. Young, D. Vavvas; Role of AMP-Dependent Kinase in Choroidal Neovascularization. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1168.
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Choroidal neovascularization (CNV) is the hallmark of neovascular age-related macular degeneration (AMD). Oxidative stress in RPE may be an important factor in its pathogenesis. AMP dependent kinase is a key energy sensor for the cell, especially in stress conditions where AMP levels rise. Moreover, AMPK has been linked to angiogenesis and inflammation. The aim of the current study was to investigate the potential role of AMPK in the molecular events of choroidal neovascularization.
CNV was induced by laser photocoagulation in 6-8weeks old male wild-type C57Bl/6 mice. Ten 532nm laser spots (100mW,100msec,100µm spot) were applied to the posterior pole using a coverslip as a contact lens. Twelve eyes of six mice were included in the study. Control mice (n=2) did not receive any laser. Animals were sacrificed and eyes were enucleated at day 3 and 5 after CNV induction and the whole choroid-RPE complex isolated and protein was extracted. The level of protein expression of phoshorylated-AMPK was evaluated by Western blot analysis from mice with or without laser treatment. To investigate further, whether genetic ablation of AMPK2 catalytic isoform has any impact on the angiographic leakage of the neovascular membrane, we induced CNV lesions in mice lacking AMPK2 isoform and in control mice. Two weeks later fluorescein angiograms were undertaken and graded by a masked observer.
Phospho-AMPK was upregulated by 3 fold 3 days after laser injury (p=0.008) compared to control animals. Its activity decreased by day 5 but was above baseline (2 fold increase, p= 0.025. Furthermore, vascular leakage was significantly decreased by 20% in mutant mice compared to wild type controls.
Using the murine model of CNV, we have demonstrated that phospho-AMPK is upregulated 3 days after CNV induction. Interestingly, this upregulation occurs at the peak of macrophage infiltration in the CNV area and at the peak of VEGF expression. Moreover, genetic ablation of AMPK2 isoform leads to decreased angiographic leakage. The role of AMPK in CNV formation needs further investigation.
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