Tissue-Specific Regulation of Autophagy by PROPPINs

PROJECT SUMMARY/ABSTRACT In multicellular organisms, disparate cell types use the same cellular mechanisms to perform common and unique functions. Autophagy is one mechanism that diverse cells use to maintain homeostasis during development and maintenance of function in adulthood. Misregulation of autophagy has been implicated in myriad human diseases and disorders; however, relatively little is known about how basal autophagy is differentially regulated in distinct cell types. PROPPIN (β-propellers that bind phosphoinositides) family members WIPI1-WIPI4 are critical autophagy components that bind to PI3P, but whose roles in tissue development versus maintenance are not well understood. This gap in knowledge has prevented understanding how basal autophagy is regulated in distinct tissues. The long-term goal is to elucidate the molecular mechanisms that regulate basal autophagy in distinct cell types to identify potential therapeutic targets for autophagy-related diseases. The overall objective in this application is to uncover how PROPPINs regulate basal autophagy independently and synergistically, and how that modulation changes during development and tissue maintenance. The central hypothesis is that PROPPINs differentially regulate basal autophagy at discrete developmental stages in distinct tissues, leading to divergent control of downstream cellular functions. The rationale is that identification of how PROPPINs regulate autophagy in distinct cell types will yield potential therapeutic targets that can be leveraged to treat diverse human diseases. The central hypothesis will be tested by pursuing three areas of focus: 1) what distinct roles do PROPPINs play during tissue development and maintenance of function; 2) how do PROPPINs act synergistically and independently to modulate basal autophagy; and 3) how do posttranslational modifications of PROPPINs regulate basal autophagy across cells and tissues? In the first area of focus, Caenorhabditis elegans will be used to elucidate how PROPPINs modulate tissue development versus maintenance of function across distinct tissues. In the second area of focus, the separate and overlapping roles of WIPI1-WIPI4 in basal autophagy will be dissected in murine cell culture. Finally, the third area of focus will examine the effects of WIPI2 posttranslational modifications on basal autophagy in distinct tissues in C. elegans. The research proposed in this application is innovative because it leverages in vivo microscopy examining endogenous autophagy reporters in the context of intact animals with advanced cell culture and biochemical techniques to ask how PROPPINs regulate basal autophagy in distinct tissues during development and adulthood. The proposed research is significant because it is expected to identify how PROPPINs differentially modulate basal autophagy and cellular functions in distinct tissues. Ultimately, the knowledge generated by this proposal has the potential to provide new opportunities for the development of innovative therapies for numerous human diseases.