Biology subjects

Thornton, C.

Publications and source records attributed to Thornton, C..

6 recordsLinked to original sources

bioRxiv2026

ACTIVATION OF THE ARYL HYDROCARBON RECEPTOR REDUCES VISCERAL HYPERSENSITIVITY IN A MOUSE MODEL OF COLITIS IN REMISSION

The aryl hydrocarbon receptor (AhR) is expressed on gut-projecting transient receptor potential vanilloid-1 (TRPV1)+ nociceptors, but whether it has a role in regulating abdominal pain remains to be determined. Approximately 50% of inflammatory bowel disease (IBD) patients experience chronic abdominal pain, even when their inflammatory disease is in remission. Previous work has shown that tryptophan metabolism to indole derivatives is reduced in IBD patients. Since microbial tryptophan metabolites (indole derivatives) serve as ligands for AhR, we hypothesized that reduced AhR activation contributes to enhanced pain sensitivity. We used a post-colitis mouse model of visceral hypersensitivity to examine the role of AhR as a mediator of nociception. AhR activation using both natural and synthetic agonists reduced visceral hypersensitivity in both male and female post-colitis mice. Conversely, pharmacological inhibition of AhR blocked the antinociceptive effects of indoles. Mechanistically, AhR activation by indole-3-pyruvic acid (IPyA) increased the transcription of the inward rectifying potassium channel Kir2.2, in TRPV1+ neurons and markedly reduced neuronal activation within the dorsal horn of the spinal cord. Metagenomic analysis revealed sex differences in indole-producing bacteria, with control males exhibiting enriched abundance of Akkermansia muciniphila and Alistipes compared to post-colitis males and female controls. These findings demonstrate that oral IPyA supplementation in post-colitis mice attenuates visceral hypersensitivity in part through activation of nociceptor AhR, providing insights that support the therapeutic targeting of AhR to treat abdominal pain in IBD patients in remission.

neuroscience↗

bioRxiv2026

Mitochondrial Optic Atrophy (OPA)1 expression regulates the injury response to neonatal hypoxia-ischaemia.

Neonatal hypoxic-ischaemic encephalopathy is a leading cause of mortality and long-term neurodevelopmental impairment, in which mitochondrial dysfunction is central to injury progression, yet the molecular mechanisms linking mitochondrial dynamics to neuropathology remain incompletely defined. We combined analysis of human developmental transcriptomic datasets with in vitro primary astrocyte models and an established neonatal mouse model of hypoxia-ischaemia (postnatal day 9, Rice-Vannucci model) to investigate the role of the mitochondrial fusion protein Optic Atrophy 1 (OPA1). OPA1 expression and processing were assessed by quantitative PCR and western blotting, mitochondrial function by imaging and Seahorse bioenergetic assays, and mitochondrial DNA content by quantitative PCR in both astrocytes and whole-brain tissue following injury. Hypoxia-ischaemia induced rapid proteolytic processing of OPA1 in the neonatal brain and reduced OPA1 expression in astrocytes following oxygen-glucose deprivation. Genetic reduction of OPA1 in astrocytes resulted in mitochondrial fragmentation, impaired maximal respiration and spare respiratory capacity (p<0.05), and increased susceptibility to hypoxic stress (p<0.01). In vitro, OPA1 loss was associated with significant depletion of mitochondrial DNA (p<0.05), and mitochondrial DNA content was similarly reduced in the neonatal mouse brain 24 hours after hypoxia-ischaemia compared with controls (p<0.05). In contrast, OPA1 overexpression preserved mtDNA levels and significantly reduced in vivo brain tissue loss at 7 days after injury (p<0.05), while improving astrocyte survival following metabolic stress (p<0.001). These findings identify loss of mitochondrial DNA as a previously unrecognised component of mitochondrial pathology in neonatal hypoxic-ischaemic brain injury and demonstrate that OPA1 is a key determinant of mitochondrial integrity and bioenergetic resilience. Targeting OPA1-dependent pathways may represent a novel therapeutic strategy to limit brain injury following birth asphyxia.

neuroscience↗

bioRxiv2026

Accurate quantification of canine mitochondrial DNA copy number and its evaluation as a biomarker of brain injury

Acute brain injury is challenging to manage in veterinary medicine, with limited validated means of prognostication currently available. The brain is rich in mitochondrial content and contains thousands of copies of mitochondrial DNA (mtDNA) per cell. We hypothesized that brain cell loss following acute brain injury may result in release of mtDNA into the systemic circulation. To investigate this, mtDNA-CN was measured in blood (n=4-6/group) and cerebral cortex (n=1/group) samples from dogs with and without brain injury using absolute quantification by real-time qPCR. By filtering out regions with homology to nuclear mitochondrial insertion sequences (NumtS) and repetitive regions, oligonucleotide primers were designed to the canine mitochondrial and nuclear genomes. In controls, blood mtDNA-CN ranged from 98 to 288 (mean 193{+/-}72), in cases of brain injury, there was a non-significant trend for higher mtDNA-CN, ranging from 163-453 (mean 244{+/-}106). As expected, cerebral cortex contained higher mtDNA-CN than the blood. In a single case with serial sampling, mtDNA-CN increased five days post-injury. We present for the first time an assay to accurately quantify mtDNA-CN in canine samples, with potential as a biomarker for acute brain injury in veterinary practice. Simple SummaryThis work describes a novel assay to accurately measure absolute levels of canine mitochondrial DNA copy number (mtDNA-CN) in biological samples. We describe the range of mtDNA-CN in canine blood and show pilot data suggesting that blood mtDNA-CN should be evaluated as a potential biomarker of acute brain injury.

molecular biology↗

bioRxiv2024

The Splice Index as a prognostic biomarker of strength and function in myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a slowly progressive, multisystemic disorder caused by a CTG repeat expansion in the DMPK 3UTR that leads to global dysregulation of alternative splicing. Here, we employed a composite RNA splicing biomarker called the Myotonic Dystrophy Splice Index (SI), which incorporates 22 disease-specific splice events that sensitively and robustly assesses transcriptomic dysregulation across the disease spectrum. Targeted RNA sequencing was used to derive the SI in 95 muscle biopsies of the tibialis anterior collected from DM1 individuals with baseline (n = 52) and 3-months (n = 37) outcomes. The SI had significant associations with timepoint matched measures of muscle strength and ambulation, including ankle dorsiflexion strength (ADF) and 10-meter run/fast walk speed (Pearson r = -0.719 and -0.680, respectively). Linear regression modeling showed that the combination of baseline ADF and SI was predictive of strength at 3-months (adjusted R2 = 0.830) in our cohort. These results indicate the SI can reliably capture the association of disease-specific RNA mis-splicing to physical strength and mobility and may be predictive of future function.

molecular biology↗

bioRxiv2021

Multiple ETS Factors Participate in the Transcriptional Control of TERT Mutant Promoter in Thyroid Cancers

Hotspot mutations in the TERT (telomerase reverse transcriptase) gene are key determinants of thyroid cancer progression. TERT promoter mutations (TPM) create de novo consensus binding sites for the ETS ("E26 transforming sequence") family of transcription factors. In this study, we systematically knocked down each of the 20 ETS factors expressed in thyroid tumors and screened their effects on TERT expression in seven thyroid cancer cell lines with defined TPM status. We observed that, unlike in other TPM-carrying cancers such as glioblastomas, ETS factor GABPA does not unambiguously regulate transcription from the TERT mutant promoter in thyroid specimens. In fact, multiple members of the ETS family impact TERT expression, and they typically do so in a mutation-independent manner. In addition, we observe that partial inhibition of MAPK, a central pathway in thyroid cancer transformation, is more effective at suppressing TERT transcription in the absence of TPMs. Taken together, our results show a more complex scenario of TERT regulation in thyroid cancers compared to other lineages, suggest that compensatory mechanisms by ETS and other regulators likely exist and advocate for the need of a more comprehensive understanding of the mechanisms of TERT deregulation in thyroid tumors before eventually exploring TPM-specific therapeutic strategies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=157 HEIGHT=200 SRC="FIGDIR/small/472152v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@63d70corg.highwire.dtl.DTLVardef@bb5d3corg.highwire.dtl.DTLVardef@e613a5org.highwire.dtl.DTLVardef@113bf54_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2019

Towards development of a statistical framework to evaluate myotonic dystrophy type 1 mRNA biomarkers in the context of a clinical trial

Myotonic dystrophy type 1 (DM1) is a rare genetic disorder, characterised by muscular dystrophy, myotonia, and other symptoms. DM1 is caused by the expansion of a CTG repeat in the 3-untranslated region of DMPK. Longer CTG expansions are associated with greater symptom severity and earlier age at onset. The primary mechanism of pathogenesis is thought to be mediated by a gain of function of the CUG-containing RNA, that leads to trans-dysregulation of RNA metabolism of many other genes. Specifically, the alternative splicing (AS) and alternative polyadenylation (APA) of many genes is known to be disrupted. In the context of clinical trials of emerging DM1 treatments, it is important to be able to objectively quantify treatment efficacy at the level of molecular biomarkers. We show how previously described candidate mRNA biomarkers can be used to model an effective reduction in CTG length, using modern high-dimensional statistics (machine learning), and a blood and muscle mRNA microarray dataset. We show how this model could be used to detect treatment effects in the context of a clinical trial.

bioinformatics↗