Project Summary/Abstract
Our long-term goals are to understand intracellular active Ca transport in cardiac muscle and to develop drugs
that target Ca dysregulation in heart failure. We focus on the cardiac sarcoplasmic reticulum (SR) Ca-
ATPase (SERCA2a), the large membrane enzyme that pumps Ca into the SR to relax myocytes after
contraction, and on SERCA’s regulatory proteins (regulins, RLN): phospholamban (PLB), sarcolipin (SLN)
and dwarf open reading frame peptide (DWORF). Ample experimental and clinical data indicates that
activation of muscle Ca transport is a powerful approach to numerous severe and widely spread disorders,
especially heart disease. Over decades, we have developed and used spectroscopic techniques to resolve the
structural mechanism of SERCA regulation by RLN. The challenge is great due to the complexity of the Ca
transport mechanism, which involves dynamic protein-protein interactions, and RLN mechanisms of action are
unclear or controversial. We have recently demonstrated fluorescence lifetime (FLT) methods with exquisite
precision and resolution of protein structural changes, with high-throughput acquisition enabled by rapid
scanning in a microplate reader. In screens of chemical libraries of =50,000 small-molecules, we have
identified multiple types of SERCA activators. We are poised to implement early-stage drug discovery
campaigns targeting the SERCA-RLN interaction, to identify compounds with therapeutic potential to treat Ca
dysregulation in heart failure. Our central hypotheses: (1) compounds that shift SERCA-RLN structural state
or binding have tissue-specific effects (2) compounds that enhance Ca-transport enhance myocyte contraction,
and (3) have antiarrhythmic properties. Aim 1 will accelerate discovery of compounds that target SERCA-RLN
interaction. Aim 2 will test effects on SERCA function in cardiac SR, HEK cells expressing human SERCA2a,
and in cardiomyocytes. These novel chemical probes will open new avenues to elucidate structure-function
mechanisms characteristic of SERCA-RLN. Aim 3 will enable lead discovery, using medicinal chemistry to
develop and test analogues of promising Hits from Aim 2. Outcomes of this program will be new lead-like
compounds, and a demonstrated systematic process targeting cardiac Ca-transport for drug discovery and
development. This process will be ready for implementation in large-scale discovery and development
campaigns to be pursued in future academic-industrial partnerships. For impact, we bring together an
innovative combination of techniques, technologies, and experts focused on cardiac Ca transport regulation.
This project is designed to enable future translation, while also developing tools for mechanistic understanding.
SERCA has emerged as a high-value therapeutic target for some of the greatest Public Health challenges, not
only in the heart (heart failure, arrhythmia) but also in skeletal muscle (muscular dystrophy, sarcopenia) and
non-muscle cells (Alzheimer’s, diabetes, obesity, cancer), so the significance of our proposed research
program is great and extends well beyond cardiology.
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