Biology subjects

Coghlan, H.

Publications and source records attributed to Coghlan, H..

3 recordsLinked to original sources

bioRxiv2026

Lysosomal abundance in young and aged mouse hearts assessed by In Vivo Imaging Systems (IVIS) Lysotracker imaging and autophagy-related gene expression

Lysosomal function is essential for cardiac proteostasis and cellular health, yet its regulation during ageing remains poorly defined. We hypothesised that ageing alters both the abundance of acidic organelles and the machinery supporting their acidification. Using fluorescence-based In Vivo Imaging Systems (IVIS) with Lysotracker Red in young (2-4 months) and aged (18 months) mouse hearts, we quantified whole-heart acidic-vesicle signals and assessed expression of lysosomal and autophagy-related genes (Lamp2, Atp6v1a, Sqstm1, Cd63, Atg12, Nfe2l2, M6pr) by RT-qPCR. Whole-heart labelled Lysotracker fluorescence did not differ significantly between age groups, indicating preservation of the total acidic-vesicle pool. No changes in Atp6v1a and Lamp2 expression suggest acidification capacity and structural stability are maintained, whereas the minor, upregulation of Sqstm1 might indicate increased autophagic demand and altered vesicle trafficking, which warrants further investigation. No statistical significant changes in M6pr, Atg12, or Nfe2l2 were detected, suggesting transcriptional stability in enzyme trafficking, core autophagy, and oxidative stress pathways. Regionally, atria showed higher Lysotracker signal than ventricles, consistent with known enrichment of acidic vesicular stores in atrial physiology. These findings highlight the utility of IVIS imaging of Lysotracker-labelled hearts, providing rapid whole-organ assessment of acidic vesicle distribution, albeit with limited depth resolution. Complementary techniques such as RT-qPCR analysis is essential to interpret IVIS findings, enabling insight into underlying molecular changes in lysosomal and autophagy pathways during cardiac ageing.

physiology↗

bioRxiv2025

Hepatic cellular stress response pathways exhibit species differences in basal and inducible activity

Cellular stress response pathways such as the NRF2 oxidative stress response, endoplasmic reticulum (ER) stress response and macroautophagy afford protection against many forms of drug toxicity, including the liver toxicity associated with the formation of reactive drug metabolites. To maximise the translatability of preclinical toxicology studies, an understanding of the relative hepatic stress response capacities of humans and widely-used preclinical animal species is vital. In control liver tissue, the basal gene and protein expression of stress response pathway components was found to be greater in rodents than non-rodent preclinical species and humans. In addition, following in vitro exposure to pharmacological modulators of the NRF2 and ER stress responses, rodent hepatocytes generally displayed a greater capacity, relative to those of non-rodent preclinical species and humans, for adaptation to cellular stress. Consistent with the reported lower concordance of drug toxicity between humans and rats, the latter displayed a greater level of Torin1-induced autophagic flux than all other species, while the robust transcriptional responses to thapsigargin-induced endoplasmic reticulum stress and Bardoxolone- or Ki696-mediated NRF2 activation were comparable between mouse and rat hepatocytes. In all, our results indicate that rodent preclinical species possess a greater basal and adaptive hepatic capacity for mitigation of chemical insult than non- rodent preclinical species and humans. This study represents the first to provide a comprehensive comparison of stress response pathway capacity of humans and the animal species most commonly used for preclinical drug safety assessment. Our findings can be used to inform the selection of species for safety testing of drugs with a liability for reactive metabolite-mediated liver toxicity.

pharmacology and toxicology↗

bioRxiv2022

Rats exhibit higher hepatic stress response pathway capacities compared with mice and humans

To minimise unexpected toxicities in early phase clinical studies of new drugs, it is vital to understand fundamental similarities and differences between preclinical test species and humans. We have used physiologically-based pharmacokinetic modelling to identify doses of the model hepatotoxin acetaminophen yielding similar hepatic burdens of the reactive metabolite N-acetyl-p-benzoquinoneimine in mice and rats, to enable comparison of tissue adaptive responses under conditions of equivalent chemical insult. Mice exhibited a greater degree of liver injury than rats, despite the equivalent hepatic NAPQI burden. Transcriptomic and proteomic analyses highlighted the stronger activation of stress response pathways (including the Nrf2 oxidative stress response and autophagy) in the livers of rats. Components of these pathways were also found to be expressed at a higher basal level in the livers of rats compared with both mice and humans. Our findings exemplify a systems approach to understanding differential species sensitivity to hepatotoxicity, and have important implications for species selection and human translation in the safety testing of new drug candidates.

pharmacology and toxicology↗