Igf-1/igf-1r System Implication In Proliferative Retinopathies

LORENC VE; ORTIZ S; SANCHEZ MC

Congreso; ARVO Meeting 2012; 2012

Purpose: Insulin-like growth factor-1 (IGF-1) and it´s receptor (IGF-1R) are involved during the normal vascular development of the retina as well as in the pathogenesis of retinopathy of prematurity (ROP) and proliferative diabetic retinopathy (PDR). Endothelial cell proliferation is a common feature of these retinopathies. In addition Müller cells (MC) are known to be implicated in these diseases by producing, Vascular Endothelial Growth Factor (VEGF) and IGF-1, among other factors; and by secreting metaloproteinases (MMPs) that participate in the extracellular remodeling. However, at present, it is not well known the function of IGF-1/IGF-1R system during angiogenesis. Previously we have demonstrated that IGF-1 induces the MC migration through IGF-1R activation. This cellular event was associated with IGF-1R activation for long times of IGF-1 stimulation. Herein we investigate the phosphorilate state of IGF-1R for shorter times under IGF-1 stimulus and its intracellular signaling pathway activation. In adition in an “in vivo” model the IGF-1R expression and distribution was examined at different times in retina of animals with and without Oxigen induced retinopathy (OIR).Methods: The human MIO-M1 cell line was used and cultured in presence of 10 nM IGF-1 for different times (1 to 20 minutes). The phosphorilated IGF-1R was analyzed by Western blot. Using a specific monoclonal antibody to demonstrate the specificity of the IGF-1 activation, cells were pre-incubated with anti IGF-1R antibody (αIR3) and p-IGF-1R was evaluated by WB. Retinas from animals with and without OIR were analized for IGF-1R expression at selected time points (P3, P10, P12 and P15). The localization of IGF-1R was examined by inmunofluorescence and confocal microscopy. Different retinal cell types were characterized using cell markers.Results: By Western blot we observed that, under IGF-1 stimulus, IGF-1R was rapidily phosphorilated from minute 1 since IGF-1 induction. In adition this phosphorilation was fully blocked by IGF-1R antibody, indicating that this phosphorilation was produced by IGF-1 binding to its cognitive receptor. In the in vivo model IGF-1R was expressed in the inner and outer nuclear layers as well as in blood vessels. This expression showed significant changes during retinal development and with the induction of retinopathy.Conclusions: These results demonstrate, in the in vitro model, the specific activation of IGF-1R by IGF-1; as well as, in the in vivo model, the IGF-1R distribution.