Biology subjects

Butler-Bowne, G. S.

Publications and source records attributed to Butler-Bowne, G. S..

4 recordsLinked to original sources

bioRxiv2026

Aging remodels the human muscle secretome, impairing stem cell via sphingolipid metabolism

Aging reduces skeletal muscle regenerative capacity, but how the aged environment impairs muscle stem cells (MuSCs) remains unclear. Skeletal muscle acts as a secretory organ, yet age-related changes in its secretome and impact on stem cells are poorly understood. We performed proteomic and lipidomic analyses of conditioned media from primary muscle cells of young (15-25 years) and aged (60-86 years) donors. We identified 127 age-dependent secreted proteins, revealing major remodeling. The lysosomal enzyme acid sphingomyelinase (ASM), which converts sphingomyelin into ceramide, was the most upregulated factor. Recombinant ASM reduced PAX7+ MuSCs in young cultures, showing extracellular ASM impairs stem cell maintenance. Lipidomics revealed disruption of the sphingomyelin-ceramide-S1P axis, with decreased sphingomyelin and S1P, a lipid promoting MuSC proliferation. Exogenous S1P restored the stem cell pool in aged cultures. These findings link secretome remodeling and sphingolipid metabolism to MuSC decline and identify ASM and S1P as targets

cell biology↗

bioRxiv2024

Different outcomes of endurance and resistance exercise in skeletal muscles of Oculopharyngeal muscular dystrophy.

BackgroundExercise is widely considered to have beneficial impact on skeletal muscle aging. In addition, there are also several studies demonstrating a positive effect of exercise on muscular dystrophies. Oculopharyngeal muscular dystrophy (OPMD) is a late-onset autosomal dominant inherited neuromuscular disorder caused by mutations in the PAPBN1 gene. These mutations consist in short (1-8) and meiotically stable GCN trinucleotide repeat expansions in its coding region responsible for the formation of PAPBN1 intranuclear aggregates. This study aims to characterize the effects of two types of chronic exercise, resistance and endurance, on the OPMD skeletal muscle phenotype using a relevant murine model of OPMD. MethodsIn this study, we tested two protocols of exercise. In the first, based on endurance exercise, FvB (wild-type) and A17 (OPMD) mice underwent a 6-week-long motorized treadmill protocol consisting in 3 sessions per week of running 20cm/s for 20 minutes. In the second protocol, based on resistance exercise generated by chronic mechanical overload (OVL), surgical removal of gastrocnemius and soleus muscles was performed, inducing hypertrophy of the plantaris muscle. In both types of exercise, muscles of A17 and FvB mice were compared to those of respective sedentary mice. For all the groups, force measurement, muscle histology and molecular analyses were conducted. ResultsFollowing the endurance exercise protocol, we did not observe any major changes in the muscle physiological parameters, but an increase in the number of PABPN1 intranuclear aggregates and enhanced collagen deposition in the exercised A17 OPMD mice. In the resistance overload protocol, we also observed an increased collagen deposition in the A17 OPMD mice which was associated with larger muscle mass and fiber cross sectional area and increased absolute maximal force as well as a reduction in PABPN1 aggregate number. ConclusionsRunning exercise and mechanical overload led to very different outcome in skeletal muscles of A17 mice. Both types of exercise enhanced collagen deposition but while the running protocol increased aggregates, the OVL reduced them. More importantly OVL reversed muscle atrophy and maximal force in the A17 mice. Our study performed in a relevant model gives an indication of the effect of different types of exercise on OPMD muscle which should be further evaluated in humans for future recommendations as a part of the lifestyle of individuals with OPMD.

pathology↗

bioRxiv2020

Lamin-related congenital muscular dystrophy alters mechanical signaling and skeletal muscle growth

BackgroundLaminopathies are a clinically heterogeneous group of disorders caused by mutations in the LMNA gene, which encodes the nuclear envelope proteins lamins A and C. The most frequent diseases associated with LMNA mutations are characterized by skeletal and cardiac involvement, and include autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy type 1B, and LMNA-related congenital muscular dystrophy (LMNA-CMD). Although the exact pathophysiological mechanisms responsible for LMNA-CMD are not yet understood, severe contracture and muscle atrophy suggest that impair skeletal muscle growth may contribute to the disease severity. MethodsWe used human muscle stem cells (MuSCs) carrying 4 different LMNA mutations and two mouse models of muscle laminopathies, representing a spectrum of disease severity, to investigate the ability of skeletal muscle to differentiate and to hypertrophy in response to mechanical challenges. We extended these finding to individuals with LMNA-related muscular dystrophy using muscle biopsies. ResultsIn vitro, we observe impaired myogenic differentiation with disorganized cadherin/{beta} catenin adhesion complexes in MuSCs carrying LMNA-CMD. We show that skeletal muscle from Lmna-CMD mice is unable to hypertrophy in response to functional overload, due to defective accretion of activated MuSCs, defective protein synthesis and defective remodeling of the neuro-muscular junction. Moreover, stretched myotubes and overloaded muscle fibers with LMNA-CMD mutations display aberrant mechanical regulation of the Yes-Associated Protein (YAP), a key sensor and mediator of mechanical cues. We also observe defects in MuSC activation and YAP signaling in muscle biopsies from LMNA-CMD patients. These phenotypes are not recapitulated in closely-related EDMD models. ConclusionsCombining studies in vitro, in vivo and patient samples, we find that LMNA-CMD mutations interfere with mechano-signaling pathways in skeletal muscle, implicating defective skeletal muscle growth as a pathogenic contributor for the severity of LMNA-related muscular dystrophy.

physiology↗

bioRxiv2019

A gold standard method for human cell quantification after xenotransplantation

Xenotransplantation of human cells into immunodeficient mouse models is a very powerful tool and an essential step for the pre-clinical evaluation of therapeutic cell-and gene-based strategies. Here we describe an optimized protocol combining immunofluorescence and real-time quantitative PCR to both quantify and visualize the fate and localization of human myogenic cells after injection in regenerating muscles of immunodeficient mice. Whereas real-time quantitative PCR-based method provides an accurate quantification of human cells, it does not document their specific localization. The addition of an immunofluorescence approach using human-specific antibodies recognizing engrafted human cells gives information on the localization of the human cells within the host muscle fibres, in the stem cell niche or in the interstitial space.\n\nThese two combined approaches offer an accurate evaluation of human engraftment including cell number and localization and should provide a gold standard to compare results obtained either using different types of human stem cells or comparing healthy and pathological muscle stem cells between different research laboratories worldwide.

cell biology↗