Biology subjects

Thomas, N. T.

Publications and source records attributed to Thomas, N. T..

3 recordsLinked to original sources

bioRxiv2026

Skeletal Muscle Stem Cell-Derived Myonuclei Adopt Divergent Terminal Transcriptional States in Adult and Aged Muscle In Response to a Hypertrophic Stimulus

Skeletal muscle stem cells (MuSCs) give rise to a fusogenic cell population that provide new myonuclei to muscle fibers. Myonuclear functional heterogeneity has recently become appreciated, but the terminal identity of MuSC-Derived myonuclei remains undefined. We performed single-nucleus RNA-sequencing of myonuclei in Adult and Aged muscle to define MuSC-Derived and resident myonuclear responses to mechanical overload (MOV), which induces a hypertrophic stimulus. We found a MuSC-dependent induction of a youthful transcriptional signature in resident myonuclei after MOV in Aged muscle. Age determined terminal transcriptional states of MuSC-Derived myonuclei toward MTJ in Adult, NMJ in Aged, and muscle spindles in both ages. Microtubule-remodeling genes, Macf1, Map1b, and Nav3, along with the transcription factor Runx1, identified this post-fusion specialization with greater expression of these genes in Adult than in Aged MuSC-Derived myonuclei. In-silico transcription factor KO screen identified Runx1 as a regulator of post-fusion specialization and Esrrg as a driver of spindle (intrafusal) MuSC-Derived myonuclear maturation. By defining the age-associated fate of MuSC fusion to muscle fibers, we provide potential targets for modulating muscle plasticity.

molecular biology↗

bioRxiv2025

Pediatric CHOP Chemotherapy Acutely Disrupts Satellite-Cell Dynamics and Blunts Muscle Mass in a Sex-Specific Manner

Pediatric cancer survival now exceeds 85 percent owing, in part, advances and use of combination chemotherapy treatments such as CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone). Despite its efficacy, CHOP may cause deleterious off-target effects during critical pediatric development periods such as impairments of skeletal muscle. We evaluated the acute effects of a CHOP administered to C57Bl/6J mice from postnatal day 28 to 48. CHOP slowed body-weight gain and has smaller gastrocnemius fiber cross-sectional area by approximately 25 percent in both sexes. mRNA sequencing detected 214 differentially expressed genes in males and 217 in females relative to controls, yet only 29 transcripts overlapped. Males exhibited downregulation of myogenic regulators, indicating impaired progenitor maintenance, whereas females showed an upregulation of extracellular-matrix and translational machinery genes plus cell-cycle regulators. Using immunohistochemistry to assess satellite cell abundance, there were 60% fewer satellite cells in males and a 40% fewer in females, which supported our transcriptional findings. These results demonstrate that pediatric CHOP acutely disrupts muscle stem-cell dynamics via sex-specific molecular programs and identify satellite-cell depletion as a potential target for preserving muscle health in pediatric cancer survivors.

physiology↗

bioRxiv2024

The 24-Hour Time Course of Integrated Molecular Responses to Resistance Exercise in Human Skeletal Muscle Implicates MYC as a Hypertrophic Regulator That is Sufficient for Growth

Molecular control of recovery after exercise in muscle is temporally dynamic. A time course of biopsies around resistance exercise (RE) combined with -omics is necessary to better comprehend the molecular contributions of skeletal muscle adaptation in humans. Vastus lateralis biopsies before and 30 minutes, 3-, 8-, and 24-hours after acute RE were collected. A time-point matched biopsy-only group was also included. RNA-sequencing defined the transcriptome while DNA methylomics and computational approaches complemented these data. The post-RE time course revealed: 1) DNA methylome responses at 30 minutes corresponded to upregulated genes at 3 hours, 2) a burst of translation- and transcription-initiation factor-coding transcripts occurred between 3 and 8 hours, 3) global gene expression peaked at 8 hours, 4) ribosome-related genes dominated the mRNA landscape between 8 and 24 hours, 5) methylation-regulated MYC was a highly influential transcription factor throughout the 24-hour recovery and played a primary role in ribosome-related mRNA levels between 8 and 24 hours. The influence of MYC in human muscle adaptation was strengthened by transcriptome information from acute MYC overexpression in mouse muscle. To test whether MYC was sufficient for hypertrophy, we generated a muscle fiber-specific doxycycline inducible model of pulsatile MYC induction. Periodic 48-hour pulses of MYC over 4 weeks resulted in higher muscle mass and fiber size in the soleus of adult female mice. Collectively, we present a temporally resolved resource for understanding molecular adaptations to RE in muscle and reveal MYC as a regulator of RE-induced mRNA levels and hypertrophy.

cell biology↗