# High-Throughput Cardiac Hypertrophy Phenotyping Supports Lead Optimization of GRK5 Inhibitors

## TL;DR

The study introduces a high-throughput screening method to optimize GRK5 inhibitors for treating cardiac hypertrophy.

## Contribution

A novel high-throughput phenotyping assay for cardiac hypertrophy and insights into GRK5 inhibitor optimization.

## Key findings

- A mixed cell culture model enabled assessment of cardiac hypertrophy in a physiologically relevant environment.
- GRK5 inhibition showed potential for therapeutic benefit, with diastereomers 4a/b identified as effective probes.
- Lipophilic and reactive compounds negatively impacted GRK5 inhibitor efficacy.

## Abstract

Cardiac hypertrophy poses a clinical challenge in heart
failure
progression with limited therapeutic options to reverse the process
of pathological remodeling. We present a high-throughput phenotypic
screening assay designed to support lead optimization from novel approaches.
A mixed cell culture from neonatal rat hearts was established, allowing
simultaneous assessment of cardiomyocytes and noncardiomyocytes within
a shared physiologically relevant microenvironment. Customized CellProfiler-based
image analysis extracted multiparametric morphological data that was
merged in a “Hypertrophy Score” metric for quantitative
analyses. The assay was applied to investigate G protein-coupled receptor
kinase 5 (GRK5) as a promising target in cardiac hypertrophy. Structure–activity
and −property relationships from a focused GRK5 inhibitor collection
revealed a negative influence on cellular efficacy by lipophilic and
covalently reactive compounds. Correlating biochemical with cellular
data eliminated GRK6 as a common off-target concern and underlined
the value of potent GRK5 versus GRK2 inhibition. Diastereomers 4a/b were identified as valuable chemical probes.