High-throughput screen for ER/SR calcium stabilizers identifies a drug for partially correcting disease phenotype in RYR1 mutant zebrafish

Authors

• ES Wires
• T Lawal
• JJ Todd
• MJ Henderson
• BK Harvey
• K Meilleur

Abstract

RYR1 encodes the major skeletal muscle calcium release channel located within the sarcoplasmic reticulum (SR) of muscle cells. Compromised function and/or reduced expression of RyR1 protein lead to dysregulation of calcium flux. Affected individuals present with muscle weakness, hypotonia, contractures, scoliosis, and, in severe cases ophthalmoplegia and/or respiratory insufficiency. There are currently no FDA-approved treatments for RYR1-RM, and this need for therapeutics in over 1200 rare disorders has resulted in an incentivized FDA process to expedite orphan drug development. Previously, monitoring SR calcium dysregulation in the context of disease progression has been technically challenging. We implemented a novel biomarker, GLuc-SERCaMP. GLuc-SERCaMP is a modified Gaussia (GLuc) luciferase protein that is retained in the lumen of the SR under physiological conditions. Upon SR calcium depletion, GLuc-SERCaMP is secreted and assayed from extracellular fluid. The advent of this technology has facilitated the development of high throughput screens for potential SR calcium- stabilizing compounds. In collaboration with NCATS, we used GLuc-SERCaMP to identify drug candidates for stabilizing SR calcium fluctuations. We also used GLuc-SERCaMP to assess SR calcium depletion in primary muscle cells from healthy donors and individuals with RYR1 variants. Furthermore, we assessed movement in a previously characterized RYR1-RM zebrafish model, termed relatively relaxed (ryr), following treatment with a drug candidate identified in the NCATS screen. Here we demonstrate the use of a novel biomarker to monitor SR calcium depletion in primary muscle cells and present data from ryr zebrafish treated with a compound identified in the NCATS high throughput screen.

Scientific Focus Area: Cell Biology

This page was last updated on Friday, March 26, 2021