Mechanisms of Selective Autophagy Macroautophagy (referred to as autophagy) is a process whereby cells sequester cytosolic components/organelles via a highly regulated pathway that terminates with the lysosomal-mediated degradation of the cargo and the recycling of macromolecules back into the cytosol. While initially thought to be a non-specific process of bulk degradation, recent work has revealed several forms of selective autophagy that play key roles in multiple biological processes. The various types of selective autophagy are regulated on multiple levels, using a repertoire of specific autophagy receptors, which recognize distinct cargo as well as a diverse family of ATG8 proteins that associate with the autophagosome and bind cargo receptors. Prior work has implicated autophagy in the control of cellular iron levels through the degradation of ferritin (a protein that forms a complex which sequesters free iron); however, the mechanism underlying this activity remained unclear. Through advanced quantitative proteomics, our laboratories discovered NCOA4 as the autophagy receptor for ferritin degradation (ferritinophagy). Moreover, our preliminary data suggests that this process is highly regulated at several levels, including the degradation of NCOA4 in response to iron. These findings provide us with the unprecedented opportunity to mechanistically dissect the biochemical basis for ferritinophagy, as well as to elucidate how ferritinophagy is integrated with other forms of selective autophagy (i.e. mitophagy) that contribute to iron homeostasis and oxidative stress control. The overarching hypothesis of this proposal is that the various forms of selective autophagy are highly regulated to coordinate critical cellular processes such as the regulation of bioavailable iron. Against this backdrop, we propose the following Aims:
AIM 1. BIOCHEMICAL MECHANISMS REGULATING FERRITINOPHAGY AND INTEGRATION INTO GLOBAL AUTOPHAGY PATHWAYS. These studies will elucidate mechanisms underlying the selectivity of cargo recognition and recruitment to autophagosomes in ferritinophagy and other forms of selective autophagy.
AIM 2. TO EXPLORE THE COOPERATIVE FUNCTIONS OF MITOPHAGY AND FERRITINOPHAGY IN RESPONSE TO CELLULAR STRESSORS. These studies will elucidate the contributions of ferritinophagy and mitophagy to critical cellular functions.
Aim 3. TO ELUCIDATE THE IMPORTANCE OF AUTOPHAGY IN TISSUE HOMEOSTASIS IN VIVO THROUGH THE CONTROL OF IRON METABOLISM. These studies will use mouse models where autophagy is conditionally inhibited in an inducible fashion as well as a conditional NCOA4 knockout mouse to understand the role of autophagy and specifically ferritinophagy in erythrogenesis through its control of bioavailable iron.
Selective autophagy involves the recognition and degradation of specific cargo which can play a role in key biological processes such as the regulation of bioavailable iron by ferritinophagy. These studies will elucidate the mechanisms of cargo selectivity of ferritinophagy and other forms of selective autophagy as well as their contributions to critical cellular functions.
Showing the most recent 10 out of 39 publications
