Biology subjects

Dort, J.

Publications and source records attributed to Dort, J..

3 recordsLinked to original sources

bioRxiv2023

Inhibition of Type I PRMTs Reforms Muscle Stem Cell Identity Enhancing their Therapeutic Capacity

In skeletal muscle, muscle stem cells (MuSC) are the main cells responsible for regeneration upon injury. In diseased skeletal muscle, it would be therapeutically advantageous to replace defective MuSCs, or rejuvenate them with drugs to enhance their self-renewal and ensure long-term regenerative potential. One limitation of the replacement approach has been the inability to efficiently expand MuSCs ex vivo, while maintaining their stemness and engraftment abilities. Herein, we show that inhibition of type I protein arginine methyltransferases (PRMTs) with MS023 increases the proliferative capacity of ex vivo cultured MuSCs. Single cell RNA sequencing (scRNAseq) of ex vivo cultured MuSCs revealed the emergence of subpopulations in MS023-treated cells which are defined by elevated Pax7 expression and markers of MuSC quiescence, both features of enhanced self-renewal. Furthermore, the scRNAseq identified MS023-specific subpopulations to be metabolically altered with upregulated glycolysis and oxidative phosphorylation (OxPhos). Transplantation of MuSCs treated with MS023 had a better ability to repopulate the MuSC niche and contributed efficiently to muscle regeneration following injury. Interestingly, the preclinical mouse model of Duchenne muscular dystrophy had increased grip strength with MS023 treatment. Our findings show that inhibition of type I PRMTs increased the proliferation capabilities of MuSCs with altered cellular metabolism, while maintaining their stem-like properties such as self-renewal and engraftment potential.

molecular biology↗

bioRxiv2022

Apelin Stimulation of the Perivascular MuSC Niche Enhances Endogenous Repair in Muscular Dystrophy

Impaired skeletal muscle stem cell (MuSC) function has long been suspected to contribute to the pathogenesis of muscular dystrophy (MD). Here we describe that defects in the endothelial cell (EC) compartment of the perivascular stem cell niche in three different types of MD are associated with inefficient mobilization of MuSCs following tissue damage. Using chemoinformatic analysis, we identified the 13 amino acid form of the peptidic hormone apelin (AP-13) as a candidate for systemic stimulation of skeletal muscle ECs. In dystrophic mice, administration of AP-13 generates a pro-myogenic EC-rich niche that supports MuSC function and markedly improves tissue regeneration, muscle strength, and physical performance. Moreover, we demonstrate that EC specific knockout of the AP-13 receptor leads to regenerative defects that phenocopy major pathological features of MD. Altogether, we provide in vivo proof-of-concept that enhancing endogenous repair by targeting the perivascular niche is a viable therapeutic avenue for MD and characterize AP-13 as a novel drug candidate for systemic treatment of stem cell dysfunction.

cell biology↗

bioRxiv2021

ERK3-MK5 signaling regulates myogenic differentiation and muscle regeneration by promoting FoxO3 degradation

The physiological functions and downstream effectors of the atypical mitogen-activated protein kinase ERK3 remain to be characterized. We recently reported that mice expressing catalytically-inactive ERK3 (Mapk6KD/KD) exhibit a reduced post-natal growth rate as compared to control mice. Here, we show that genetic inactivation of ERK3 impairs post-natal skeletal muscle growth and adult muscle regeneration after injury. Loss of MK5 phenocopies the muscle phenotypes of Mapk6KD/KD mice. At the cellular level, genetic or pharmacological inactivation of ERK3 or MK5 induces precocious differentiation of C2C12 or primary myoblasts, concomitant with MyoD activation. Reciprocally, ectopic expression of activated MK5 inhibits myogenic differentiation. Mechanistically, we show that MK5 directly phosphorylates FoxO3, promoting its degradation and reducing its association with MyoD. Depletion of FoxO3 rescues in part the premature differentiation of C2C12 myoblasts observed upon inactivation of ERK3 or MK5. Our findings reveal that ERK3 and its substrate MK5 act in a linear signaling pathway to control post-natal myogenic differentiation.

cell biology↗