| Project Detail |
Autophagy is a cellular mechanism that mediates the intracellular degradation and recycling of cytoplasmic contents. A basal (or constitutive) level of autophagy is required to keep cells (particularly postmitotic cells) free of damaged proteins and organelles. Induced (or adaptive) autophagy is a stress-response that facilitates cell survival by recycling intracellular components. Mitophagy is a selective autophagy pathway whereby mitochondria are degraded inside lysosomes by autophagy. Its most known role is to act as quality control pathway eliminating damaged mitochondria.We recently demonstrated that mitophagy has other essential functions in cells. Mitophagy also regulates neurogenesis by reprogramming cell metabolism. Animals deficient in the mitophagy receptor NIX exhibit marked alterations in the neurogenesis of retinal ganglion cells; the first neurons to undergo differentiation in the vertebrate retina. Furthermore, NIX-deficient animals accumulate mitochondria in different retinal layers, display metabolic alterations and vision defects. Interestingly, these alterations are associated with impaired photoreceptor function, suggesting a heretofore-undescribed role of mitophagy in sustaining photoreceptor homeostasis. Mitophagy research has lagged behind other fields due to a paucity of robust investigative tools. This project will use a recently developed mouse model that enables analysis of mitophagy in vivo. Our data using the mito-QC animals also shows high levels of basal mitophagy in normal conditions in the adult retina, in particular in photoreceptor cells and the retinal pigmented epithelium (RPE) suggesting a prominent role of mitophagy in the retina.The overall objective of this project is to better understand the physiological roles of NIX-dependent mitophagy in the retina. We will compare the developmental and adult phenotype of deleting NIX in cones, rods and the retinal pigmented epithelium by using Cre-recombinase under the control of cell type specific promoters. To assess the degree of mitophagy downregulation those models will be crossed with the mito-QC reporter mice and mitophagy will be compared in the target cell versus the other retinal cell types. In each of these experimental settings, we will examine the quality-control function of mitophagy assessing the effects of mitophagy downregulation on mitochondrial damage and oxidative stress. We will also investigate other roles of mitophagy such as mitochondrial remodelling, metabolism and the link between mitophagy and cell death. We will also evaluate the functional visual alterations in all the NIX-deficient models. Last, using two models of retinal degeneration we will determine whether boosting mitophagy could be a new therapeutic approach for retinal diseases. The overall aim of this project is to uncover the roles NIX-dependent mitophagy in the vertebrate retina and to determine how alterations in these processes affect retinal physiology and pathology. This project will combine robust, unique and quantitative tools from confocal microscopy, image analysis, flow cytometry and omics approaches together with non-invasive determinations of visual function to understand why NIX-dependent mitophagy is essential to sustain retinal function in vivo. The data obtained will have a positive impact in understanding the fundamental role of selective autophagy in the physiology and pathology of the central nervous system. Moreover, it could lead to the development of new therapeutic approaches for neurodegenerative diseases and conditions associated to mitochondrial alterations. |
