Biology subjects

Ludlow, A. T.

Publications and source records attributed to Ludlow, A. T..

4 recordsLinked to original sources

bioRxiv2025

Telomerase mRNA Reduces Radiation-induced DNA Damage of human skin

Over four million people undergo radiation therapy annually in the United States. Among these, more than 90% experience varying degrees of radiation-induced skin injury. Despite the enormity of the problem, there is currently no FDA-approved agent to prevent or treat skin damage caused by ionizing radiation. In the current study, ionizing radiation induced dose-dependent genomic and mitochondrial DNA damage, leading to apoptosis in primary cutaneous cells. Prior treatment with mRNA encoding telomerase reverse transcriptase (TERT) substantially reduced radiation-induced DNA damage in human primary skin cells and tissues. Mechanistically, TERT mRNA pretreatment enhances DNA repair, reduces mitochondrial ROS, and decreases apoptosis without extending telomere length during the experimental period, suggesting a non-canonical function of TERT to accelerate the cellular recovery from radiation. These findings highlight a potential therapeutic approach for preventing radiation-induced skin injury. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=197 HEIGHT=200 SRC="FIGDIR/small/636031v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@5bcee4org.highwire.dtl.DTLVardef@16c0c28org.highwire.dtl.DTLVardef@922c5dorg.highwire.dtl.DTLVardef@9eafd0_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

The Impact of Acute Endurance Exercise on Alternative Splicing in Skeletal Muscle

II:PurposeAlternative splicing (AS) is a highly conserved post-transcriptional mechanism, generating mRNA variants to diversify the proteome. Acute endurance exercise appears to transiently perturb AS in skeletal muscle, but transcriptome-wide responses are not well-defined. We aimed to better understand differential AS (DAS) and differential isoform expression (DIE) in skeletal muscle by comparing short-read (SRS) and long-read RNA sequencing (LRS) data. MethodsPublicly accessible SRS of clinical exercise studies were extracted from the Gene Expression Omnibus. Oxford Nanopore LRS was performed on mouse gastrocnemius before and following treadmill exercise (30m running, n=5 mice/group, 20 total, 10 weeks old). Differential gene expression (DGE) and DIE were analyzed and validated using RT-PCR and immunoblots. ResultsBoth SRS and LRS illustrated significant DGE in skeletal muscle post-exercise, including 89 RNA-binding proteins (RBPs). rMATS analysis of SRS revealed that exon-skipping and intron-retaining events were the most common. Swan analysis of LRS revealed several common genes across post-exercise cohorts with significant DAS but no DGE: 13 exercise-associated genes, including mSirt2 (24.5% shift at 24hr post-exercise [24pe], p=0.005); 61 RBPs, including mHnrnpa3 (28.5% at 24pe, p=0.02), mHnrnpa1 (30.6% at 24pe, p=0.004), and mTia1 (53.6% at 24pe, p=0.004). ConclusionsWe illustrated that acute endurance exercise can elicit changes in AS-related responses and RBP expression in skeletal muscle, especially at 24pe. SRS is a powerful tool for analyzing DGE but lacks isoform detection, posing a major gap in knowledge of "hidden" genes with no transcriptional but significant DIE and protein expression changes. Additionally, LRS can uncover previously unknown transcript diversity and mechanisms influencing endurance exercise adaptations and responses.

physiology↗

bioRxiv2024

Relative rDNA copy number is not associated with resistance training-induced skeletal muscle hypertrophy and does not affect myotube anabolism in vitro

Ribosomal DNA (rDNA) copies are organized in tandem repeats across multiple chromosomes, and inter-individual variation in rDNA copy number has been speculated to be a modifier of the hypertrophic responses to resistance training. In the current study, 82 apparently healthy participants (n=53 males, 21{+/-}1 years old; n=29 females, 21{+/-}2 years old) performed 10-12 weeks of supervised full-body resistance training. Whole-body, mid-thigh, and histological skeletal muscle hypertrophy outcomes were determined, as was relative rDNA copy number from pre-intervention vastus lateralis (VL) biopsies. Pre- and post-intervention VL biopsy mRNA/rRNA markers of ribosome content and biogenesis were assayed in all participants, and these targets were also assayed in the 29 females 24 hours following their first workout bout. Across all 82 participants, no significant associations were evident between relative rDNA copy number and training-induced changes in whole body lean mass (r = -0.034, p=0.764), vastus lateralis thickness (r = 0.093, p=0.408), mean myofiber cross-sectional area (r = -0.128, p=0.259), or changes in muscle RNA concentrations (r = 0.026, p=0.818). Several significant, positive associations in females support ribosome biogenesis being linked to training-induced myofiber hypertrophy. Follow-up studies using LHCN-M2 myotubes demonstrate a reduction in relative rDNA copy number induced by bisphenol A (BPA). However, BPA did not significantly affect myotube diameter or prevent insulin-like-growth factor-induced hypertrophy. These findings provide strong evidence that relative rDNA copy number is not associated with myofiber anabolism and provide further mechanistic evidence for ribosome biogenesis being involved in this phenomenon.

molecular biology↗

bioRxiv2019

Quantitative mitochondrial DNA copy number determination using droplet digital PCR with single cell resolution: a focus on aging and cancer

Mitochondria are involved in a number of diverse cellular functions, including energy production, metabolic regulation, apoptosis, calcium homeostasis, cell proliferation and motility as well as free radical generation. Mitochondrial DNA (mtDNA) is present at hundreds to thousands of copies per cell in a tissue-specific manner. Importantly, mtDNA copy number also varies during aging and disease progression and therefore might be considered as a biomarker that mirrors alterations within the human body. Here we present a new quantitative, highly sensitive droplet digital PCR (ddPCR) method (ddMDM; droplet digital mitochondrial DNA measurement) to measure mtDNA copy number not only from cell populations but also from single cells. Our developed assay can generate data in as little as 3 hours, is optimized for 96-well plates and also allows the direct use of cell lysates without the need for DNA purification or nuclear reference genes. Importantly, we show that ddMDM is able to detect differences between samples whose mtDNA copy number was close enough as to be indistinguishable by other commonly used mtDNA quantitation methods. By utilizing ddMDM, we show quantitative changes in mtDNA content per cell across a wide variety of physiological contexts including cancer progression, cell cycle progression, human T cell activation, and human aging.

molecular biology↗