Rewiring with biased signaling to override oxidative pathway defects for SEPN1-related myopathy therapy

Project Information

REBOOST

Grant agreement ID: 897735

DOI

10.3030/897735

Project closed

EC signature date 15 April 2020

Start date 1 May 2020

End date 30 April 2022

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 196 707,84

EU contribution

€ 196 707,84

Coordinated by

UNIVERSITE PARIS CITE
France

Periodic Reporting for period 1 - REBOOST (Rewiring with biased signaling to override oxidative pathway defects for SEPN1-related myopathy therapy)

Reporting period: 2020-05-01 to 2022-04-30

Summary of the context and overall objectives of the project

SEPN1-related myopathy (SEPN1-RM or SELENON-RM) is a rare, untreatable congenital muscle disease in which mutations of the SEPN1/SELENON gene impair the antioxidant and ER stress protection mechanisms and mitochondrial function. This ultimately leads to a significant loss of energy production in muscle cells. SEPN1-RM patients experience muscle weakness and fatigue leading to potentially-lethal respiratory failure and major life burden due to loss of mobility. Currently, there are no high-throughput or appropriate preclinical models to facilitate identification of disease-modifying drugs for most types of congenital myopathy; this has hampered efforts in devising therapeutic strategies.

We have focused on SEPN1-RM in this study as it is a model of a monogenic muscle disease which allows us to directly attribute any detectable changes in cells and signaling pathways to the primary gene defect without confounding factors. Our overall objectives to overcome the therapeutic development bottlenecks are: (1) to use patient-derived cell culture to establish a high-throughput readout of the defective bioenergetic output and (2) to test a treatment strategy by exploiting potential biased signalings, which bypass SEPN1 defects to restore cellular bioenergetics.
The findings from this study could serve as a model paradigm which could be applied to accelerate therapeutic development in other muscle conditions (including age-related muscle degeneration as well as other congenital or metabolic myopathies) associated with overlapping defects in muscle metabolism and bioenergetic.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Through this project, we have optimized a high-throughput assay (ATP-HTS) based on luminescent signal to measure cellular energy level. We have validated this assay with a large cohort of patient-derived primary fibroblast and muscle cell cultures and shown that their bioenergetic level was significantly reduced. In addition, this ATP-HTS assay could robustly detect a reduction in bioenergetic levels in peripheral blood samples from the SEPN1-deficient mouse model. This finding implies the possibility of implementing clinically this method for measuring bioenergetic status using patient plasma samples, less invasive than a muscle biopsy.

We have also performed an unbiased analysis of the SEPN1-RM patient-derived cells RNA expression and revealed a defect in a major pathway which regulates cellular bioenergetics. This defective pathway was also independently identified in SEPN1-RM patient muscle cell cultures using single-cell mass cytometry. To validate this finding, we treated SEPN1-devoid human cells with a known agonist acting on this pathway and found that treatment was efficacious in restoring the ATP (bioenergetic) content to a level comparable to that of the controls.

We communicated with our university (University Paris Cité) to evaluate the potential commercial values from our findings including the implementation of our ATP-HTS as diagnostic tool. In addition, we have uncovered a robust effect of a known agonist drug acting on a compensatory signaling pathway which enhances patient’s bioenergetic level and might represent a first treatment for this (and other related) inherited muscle disease. We are exploiting this finding as potential therapy for SEPN1-RM and submitting the provisional patent to protect it through the Erganeo team, our Technology Transfer and Innovation office of the University Paris Cité.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

There is no optimum animal or non-human cell model for SEPN1-RM, like for most types of congenital myopathy. The existing mouse model, although showing signs of oxidative stress, has a normal life span and fails to recapitulate the severe muscle phenotype observed in patients. Therefore, due to the lack of preclinical studies on validated model systems, there is a knowledge gap in the understanding of many congenital myopathies at molecular level. This has deterred efforts to identify convenient biomarkers for diagnosis, druggable targets and read-out parameters to monitor treatment impact. Our ATP-HTS provides a first validated readout for evaluating the actual pathophysiology of the disease and measure target engagement in future therapies, paving the way for therapeutic development in this untreatable disease. In addition, restoration of the bioenergetic level in SEPN1-RM by stimulating a signaling pathway is a significant step for devising a potential therapy for SEPN1-RM and, potentially, other forms of muscle dysfunction with related mechanisms (such as age-related sarcopenia) which represent major public health problems worldwide.

Figure1