Biology subjects

Turnbull, I. C.

Publications and source records attributed to Turnbull, I. C..

5 recordsLinked to original sources

bioRxiv2026

Sotatercept Reverses SIN3a Deficiency-Driven PAH by Reprogramming BMPR2/TGF-β-HIF-1α Signaling Pathways

BackgroundPulmonary arterial hypertension is a progressive and fatal cardiopulmonary disease marked by excessive proliferation of pulmonary artery smooth muscle cells (PASMCs), pathological vascular remodeling, and ultimately right heart failure. Dysregulated BMPR2 signaling is a central molecular hallmark of PAH and is often associated with epigenetic suppression of BMPR2 expression. Switch-independent 3a (SIN3a), a transcriptional co-regulator and chromatin-modifying scaffold protein, has emerged as a key regulator of BMPR2 expression, yet its role in PAH pathogenesis remains poorly defined. MethodsWe generated smooth muscle cell-specific SIN3a knockout mice (SIN3aSMC-/-) and subjected them to the Sugen/hypoxia protocol to induce PAH. A cohort received Sotatercept treatment. In parallel, human PASMCs engineered to overexpress SIN3a were exposed to TGF{beta}1 or hypoxia (1% O2) in vitro. Comprehensive transcriptomic profiling and pathway analyses identified molecular networks regulated by SIN3a and Sotatercept. Hemodynamic measurements and detailed morphometric analyses were used to assess disease severity and treatment response. ResultsSIN3a overexpression in PASMCs suppressed hypoxia-inducible factor-1 and TGF-{beta}/SMAD2/3 signaling, restored BMPR2 expression, and activated canonical BMP signaling through SMAD1/5/9 phosphorylation, while reducing pro-inflammatory, oxidative, and fibrotic gene programs. Transcriptomic analyses revealed that SIN3a and Sotatercept converge on gene networks that regulate BMPR2 signaling, ID isoforms, extracellular matrix remodeling, oxidative stress, and inflammation. In vivo, smooth muscle-specific SIN3a deletion exacerbated Sugen/hypoxia-induced PAH, increasing right ventricular systolic pressure, right ventricular hypertrophy, pulmonary vascular remodeling, and fibrosis. Sotatercept treatment reversed these pathological features, restored SIN3a and BMPR2 expression, reactivated BMP signaling, and attenuated HIF-1 and TGF-{beta} signaling in SIN3a-deficient mice. ConclusionsSIN3a is a central epigenetic regulator of PASMC homeostasis that integrates oxidative stress, inflammation, and fibrotic signaling. Loss of SIN3a accelerates PAH progression, whereas Sotatercept restores SIN3a expression, rebalances BMPR2 and TGF-{beta} signaling, and attenuates pulmonary vascular remodeling and right ventricular dysfunction. Together, these findings identify SIN3a as a disease-relevant therapeutic target and support the use of Sotatercept as a disease-modifying approach for pulmonary vascular disease.

molecular biology↗

bioRxiv2026

Micromachined Thermocouple Microprobe for Real-Time Thermometry of Hippocampal Slices during High-Frequency Stimulation

Neuronal activity is energetically demanding and generates heat as a metabolic byproduct. Here we investigated localized temperature changes in mouse hippocampal brain slices during intense synaptic activation. Using fast-response thermocouple microprobes placed in the tissue, we measured real-time temperature fluctuations during high-frequency (100 Hz) electrical stimulation of Schaffer collateral inputs. Stimulation induced a local temperature increase (peak {Delta}T = 0.54 {+/-} 0.07 {degrees}C; n = 4). In contrast, when action potentials were blocked with tetrodotoxin (TTX), the same stimulation produced no measurable temperature rise. These results demonstrate that high-frequency neural firing and synaptic transmission can transiently elevate local brain tissue temperature, presumably due to increased metabolic activity and adenosine triphosphate (ATP) consumption. The hippocampus tolerated these small temperature shifts, but even modest heating could influence neuronal function. Our findings provide direct experimental evidence linking synaptic activity to localized brain heat production, and underscore the importance of considering thermogenesis under stimulation conditions that give rise to forms of synaptic plasticity.

bioengineering↗

bioRxiv2025

Preliminary Insights into the Acute Molecular Responses in C2C12 Myotubes to Hyperthermia and Insulin Treatment.

This study investigates the differential gene expression in an immortalized cell line of mouse skeletal myoblasts (C2C12)-derived myotube cells subjected to hyperthermia (40{degrees}C) with and without insulin treatment to elucidate the impact of thermal stress on skeletal muscle physiology. Hyperthermia, which occurs during intense physical activity or environmental heat exposure, is known to challenge muscle homeostasis and influence metabolic function. mRNA sequencing revealed that hyperthermia robustly altered gene expression--upregulating key genes involved in glycolysis, oxidative phosphorylation, heat shock response, and apoptosis. These changes are suggestive of an elevated metabolic state and enhanced cellular stress; however, these results remain preliminary without complementary protein or metabolic assays. Notably, insulin treatment moderated many of the hyperthermia-induced transcriptional alterations, particularly affecting genes linked to glucose uptake and metabolism. Together, these findings provide hypothesis-generating insights into the interplay between thermal stress and insulin signaling in C2C12 myotubes, and they underscore potential targets for future mechanistic studies.

molecular biology↗

bioRxiv2024

Synergistic generation of cardiac resident-like macrophages and cardiomyocyte maturation in tissue engineered platforms

Cardiovascular disease stands as the leading cause of death globally, claiming approximately 19million lives in 2020. On the contrary, the development of cardiovascular drugs is experiencing a decline, largely due to the bottleneck in understanding the pathophysiology of various heart diseases and assessing the effects of drugs on healthy human hearts. The development of induced pluripotent stem cell (iPSC) technology and the availability of cardiac cell types in vitro, has resulted in a surge in efforts to fabricate human cardiac models for disease modelling and drug discovery applications. Although numerous attempts evidence successful fabrication of 3 dimensional (3D) engineered heart tissues, the innate immune cell population of the myocardium - particularly cardiac macrophages, was until recently, overlooke. With increasing appreciation of the interactions between cardiomyocytes and macrophages in the myocardium, in this work, isogenic populations of cardiac resident-like macrophages and cardiomyocytes were generated using iPSCs, to understand the interactions between the two cell types in both 2D and 3D settings, and subjected to electric stimulation. After characterizing iPSC-derived macrophages (iMacs) and iPSC-derived cardiomyocytes (iCMs) in depth, the conditioning of iMacs to align to a cardiac resident macrophage-like phenotype in the presence of iCMs in 2D culture was explored. In co-culture with iCMs, iMacs upregulated known genes expressed by cardiac resident macrophages. Additionally, in co-culture with iMacs, iCMs displayed an elongated morphology, improved calcium function and an increase in known maturation genes such as the ratio between MYH7 and MYH6 as well as SERCA2. In a 2D setting, iMacs showed the ability to electrically couple with iCMs and facilitate synchronous beating in iCM cultures. The 2D characterisation was translated into an engineered cardiac tissue model, wherein, improvement in tissue characteristics in the presence of iMacs was demonstrated in terms of increased cell alignment, enhanced cardiomyocyte elongation, physiologically relevant beat rates and improved tissue compaction. Taken together, these findings may open new avenues to use iMacs in engineered cardiac tissue models, not only as an innate immune cell source, but also as a support cell type to improve cardiomyocyte function and maturation.

bioengineering↗

bioRxiv2024

Pharmacological Inhibition of Epac1 Protects against Pulmonary Fibrosis by Blocking FoxO3a Neddylation

BackgroundIdiopathic Pulmonary fibrosis (IPF) is characterized by progressive scarring and fibrosis within the lungs. There is currently no cure for IPF; therefore, there is an urgent need to identify novel therapeutic targets that can prevent the progression of IPF. Compelling evidence indicates that the second messenger, cyclic adenosine monophosphate (cAMP), inhibits lung fibroblast proliferation and differentiation through the classical PKA pathway. However, the contribution of the exchange protein directly activated by cAMP 1 (Epac1) to IPF pathophysiological processes is yet to be investigated. ObjectiveTo determine the role of the cAMP-binding protein Epac1 in the progression of IPF. MethodsWe used lung samples from IPF patients or healthy controls, mouse lung samples, or lung fibroblast isolated from a preclinical mouse model of PF induced by bleomycin intratracheal injection. The effect of bleomycin (BLM) treatment was determined in Epac1 knock-out mice or wild-type littermates. Epac1 expression was modulated in vitro by using lentiviral vectors or adenoviruses. The therapeutic potential of the Epac1-selective pharmacological inhibitor, AM-001, was tested in vivo and in vitro, using a bleomycin mouse model of PF and an ex vivo precision-cut lung slices (PCLs) model of human lung fibrosis. ResultsEpac1 expression was increased in the lung tissue of IPF patients, in IPF-diseased fibroblasts and in BLM-challenged mice. Furthermore, Epac1 genetic or pharmacological inhibition with AM-001 decreased normal and IPF fibroblast proliferation and the expression of profibrotic markers, SMA, TGF-{beta}/SMAD2/3, and interleukin-6 (IL-6)/STAT3 signaling pathways. Consistently, blocking Epac1 protected against BLM-induced lung injury and fibrosis, suggesting a therapeutic effect of Epac1 inhibition on PF pathogenesis and progression. Global gene expression profiling revealed a decrease in the key components of the profibrotic gene signature and neddylation pathway in Epac1-deficient lung fibroblasts and IPF human-derived PLCs. Mechanistically, the protective effect of Epac1 inhibition against PF development involves the inhibition of FoxO3a neddylation and its subsequent degradation by NEDD8, and in part, by limiting the proliferative capacity of lung-infiltrating monocytes. ConclusionsWe demonstrated that Epac1 is an important regulator of the pathological state of fibroblasts in PF and that small molecules targeting Epac1 can serve as novel therapeutic drugs against PF.

physiology↗