Implication of Dystrophin Protein 71 (Dp71) in Retinal Angiogenesis

Abstract

Purpose: : To investigate whether dystrophin protein 71 (Dp71), the smallest product of Duchenne muscular dystrophy (DMD) gene, and key component of the membrane associated cytoskeleton has an implication in postnatal retinal angiogenesis.

Methods: : Flat mounted retinas of wild type and Dp71-null newborn mice at different ages were studied to quantify retinal vessels angiogenesis and coverage of the retina by GFAP+ astrocytes. Aortic ring assay was used to evaluate a direct effect of absence of Dp71 on angiogenesis from vessels. The localization of Dp71 in retinal was investigated by immunostaining with an anti-dystrophin antibody (H4). Relative expression of proteins was determined by Western blot and Real Time-PCR.

Results: : In absence of Dp71 postnatal angiogenesis was found inhibited until P6. A delay in the spreading of GFAP+ astrocytes was also observed and Dp71was found to be expressed in these astrocytes glial cells known to drive angiogenesis. These observations suggested that the absence of Dp71 delayed the deployment of GFAP+ astrocytes on the retina, which could act as a limiting factor for angiogenesis. After P6, astrocytes covered completely the retina, and angiogenesis activity was higher in Dp71-null mice allowing a catch-up of wild type mice vascularization at P12. This is likely related to pericytes in which we found also Dp71. Indeed, absence of Dp71 from pericytes of microvessels in aortic rings essays increased their angiogenesis at 7 days. Exploration of several angiogenesis regulation pathways (VEGF, NOS, microglial cells…) suggested that the Dp71 might act independently.

Conclusions: : Dp71 is implicated in the regulation of angiogenesis. This original effect is through cells in which Dp71 is present and then could be pro or anti-angiogenic, depending on time and localization.

Keywords: retina • astrocyte • retinal neovascularization