The overarching aim of Core D, in collaboration with Projects 1-4 and cores B and C, is to test the hypothesis that it is possible to partially reverse aging-dependent deficiencies in proteostasis network (PN) capacity (including those leading to pathology) by pharmacologic regulation of the PN employing small molecule proteostasis regulators. We will focus on heat shock response stress-responsive signaling pathway activators that regulate cytosolic PN capacity, unfolded protein response stress-responsive signaling activators that regulate secretory pathway PN capacity, and the antioxidant stress-responsive signaling pathway activators in Aim 1. Since stress-responsive signaling pathways generate an active transcription factor, we hypothesize that there will be a greater chance for an effective biological response from this evolved solution to correct proteostasis deficiencies, wherein all the components of interacting and competing PN pathways in a given subcellular compartment are up-regulated in the appropriate stoichiometry. These stress-responsive signaling pathways lead to powerful emergent functions that are only partially understood.
In Aim 1, we will further develop a technology platform to validate the pharmacodynamics (PD; the study of what a drug does to the organism), selectivity, and mechanism of action of small molecule proteostasis regulators that function through activation of stress-responsive signaling pathways in multiple organisms. We will initially employ cell-based reporters of stress-responsive signaling pathway activation (with Core B), targeted RNAseq, followed by mass spectrometry-based proteomics (Core C activities), coupled to bioinformatics to validate the proteostasis regulators. We will also assess the pharmacokinetics (PK; the study of what the organism does to a drug (metabolism)) in multiple organisms, which will help us establish reasonable dosing regimens. PK will be assessed using liquid chromatography-mass spectrometry approaches.
In Aim 2, we also seek to establish the utility of small molecule proteostasis regulators involved in enhancing the degradation of proteins, lipids and organelles, either through activation of autophagy or the ubiquitin proteasome system. We will generate PK and PD data for proteostasis regulators reported by others that activate the autophagy lysosomal pathway (degrades proteins, oligosaccharides, lipids and oligonucleotides) through an m-TOR independent mechanism and for proteostasis regulators to activate the ubiquitin proteasome system (degrades proteins). Collectively, the PK and PD data in human, murine and yeast cells and in C. elegans is important because: (1) it allows us to test and, therefore recommend, reasonable dosing regimens for proteostasis regulators, and (2) these data allow us to properly interpret experiments in model organisms, especially negative data. We will provide these validated proteostasis regulators to PIs of the projects, as well to labs working on complementary aging paradigms and aging-associated diseases to discern which proteostasis regulators correct aging-linked proteostasis deficiencies.
