Project Summary/Abstract: Alpha-1-antitrypsin (AAT) deficiency (AATD) is the most common, underdiagnosed inherited genetic condition (1:1500) and the primary modifier for chronic obstructive pulmonary disease (COPD) (300 million patients world- wide- 3 million deaths annually). AATD is an aging and genotype sensitive disease. Onset and progression results from misfolding of variant (mutant) forms of AAT in the endoplasmic reticulum (ER) of the liver leading to aggregation triggering progressive liver disease, and subsequent loss-of-function of neutrophil elastase (NE) inhibitory activity in serum and the lung leading to pulmonary failure by mid-to-late decades of life. Effective treatment of AATD is a critical unmet need. This proposal addresses an emergent challenge to understand how diverse variants in the AAT protein encoded by the genome of the world-wide population differentially contribute to both gain- and loss-of-function disease pathology and how proteostasis (the protein folding program in the cell) involving the unfolded protein response (UPR) ATF6 and IRE1/XBP1s signaling pathways, can be manipulated by small molecules to therapeutically manage disease in the individual harboring a unique variant. ATF6 and IRE/XBP1s signaling pathways adjust the capacity of the ER associated protein folding machinery including the cytosolic heat shock protein (Hsp) 70 (Hsp70) ER paralog Grp78/BIP/HSBA5 chaperone/co- chaperone system and the Hsp90 ER paralog Grp94 to restore balance in response to misfolding and ER stress. We now apply Gaussian process (GP) regression machine learning based variation spatial profiling (VSP), an innovative yet well validated tool (described in 11 publications to date for multiple proteins) that we have pioneered to advance our understanding of the spatial covariance (SCV) relationships dictating AAT fold design to develop novel therapeutic approaches for AATD. In Aims 1 and 2 we hypothesize that ATF6 and IRE1/XBP1s signaling pathways, respectively, can be adjusted to mitigate AATD using small molecule activators of these signaling pathways for nearly the entire spectrum of AAT variants in the patient population, experiments to be performed in collaboration with our Co-Investigators Drs. Kelly and Wiseman at Scripps Research. We have substantial preliminary data attesting to the effectiveness of UPR modulators across a broad spectrum of AAT variants found in the patient population (Sun et. al., (2023) Cell Chem. Biol.). We propose that these efforts will lead to effective, long term management AAT misfolding to mitigate severity of disease progression of AATD in the clinic. In Aim 3, we hypothesize that a deep understanding of the role of UPR regulated components found in the ER can explain the biology behind ATF6 and IRE1/XBP1s signaling pathway chemical modulators, providing a solid mechanistic understanding of disease to direct drug development. Through a deep understanding of GP based SCV properties of the collective...