Biology subjects

Parton, R.

Publications and source records attributed to Parton, R..

5 recordsLinked to original sources

bioRxiv2024

Maturation of human cardiac organoids are required for disease modelling and drug discovery

Cardiac maturation is an important developmental phase culminating in profound biological and functional changes to adapt to the high demand environment after birth1,2. Maturation of human pluripotent stem cell-derived human cardiac organoids (hCO) to more closely resemble human heart tissue is critical for understanding disease pathology. Herein, we profile human heart maturation in vivo3 to identify key signalling pathways that drive maturation in hCOs4,5. Transient activation of both the 5 AMP-activated kinase (AMPK) and estrogen-related receptor (ERR) promoted hCO maturation by mimicking the increased functional demands of post-natal development. hCOs cultured under these directed maturation (DM) conditions (DM-hCOs) display robust transcriptional maturation including increased expression of mature sarcomeric and oxidative phosphorylation genes resulting in enhanced metabolic capacity. DM-hCOs have functionally mature properties such as sarcoplasmic reticulum-dependent calcium handling, accurate responses to drug treatments perturbing the excitation-coupling process and ability to detect ectopy CASQ2 and RYR2 mutants. Importantly, DM- hCOs permit modelling of complex human disease processes such as desmoplakin (DSP) cardiomyopathy, which is driven by multiple cell types. Subsequently, we deploy DM-hCOs to demonstrate that bromodomain extra-terminal inhibitor INCB054329 rescues the DSP phenotype. Together, this study demonstrates that recapitulating in vivo development promotes advanced maturation enabling disease modelling and the identification of a therapeutic strategy for DSP- cardiomyopathy.

bioengineering↗

bioRxiv2023

Reversible expansion of tissue macrophages in response to macrophage colony-stimulating factor (CSF1) transforms systemic metabolism to fuel growth.

Background and AimMacrophages regulate metabolic homeostasis in health and disease. Macrophage colony-stimulating factor (CSF1)-dependent macrophages contribute to homeostatic control of the size of the liver. This study aimed to determine the systemic metabolic consequences of elevating circulating CSF1. Methods and ResultsAcute administration of a CSF1-Fc fusion protein led to monocytosis, increased resident tissue macrophages in the liver and all major organs, and liver growth. These effects were associated with increased hepatic glucose uptake and extensive mobilisation of body fat. The impacts of CSF1 on macrophage abundance, liver size and body composition were rapidly reversed to restore homeostasis. CSF1s effects on metabolism were independent of several known endocrine regulators and did not impact the physiological fasting response. Analysis using implantable telemetry in metabolic cages revealed progressively reduced body temperature and physical activity with no change in diurnal food intake. ConclusionThese results demonstrate the existence of a dynamic equilibrium between CSF1, the mononuclear phagocyte system, metabolic regulation and homeostatic control of liver:body weight ratio.

immunology↗

bioRxiv2022

ACE2 is necessary for SARS-CoV-2 infection and sensing by macrophages but not sufficient for productive viral replication

Macrophages are key cellular contributors to COVID-19 pathogenesis. Whether SARS-CoV-2 can enter macrophages, replicate and release new viral progeny remains controversial. Similarly, whether macrophages need to sense replicating virus to drive cytokine release is also unclear. Macrophages are heterogeneous cells poised to respond to their local microenvironment, and accordingly, the SARS-CoV-2 entry receptor ACE2 is only present on a subset of macrophages at sites of human infection. Here, we use in vitro approaches to investigate how SARS-CoV-2 interacts with ACE2-negative and ACE2-positive human macrophages and determine how these macrophage populations sense and respond to SARS-CoV-2. We show that SARS-CoV-2 does not replicate within ACE2-negative human macrophages and does not induce pro-inflammatory cytokine expression. By contrast, ACE2 expression in human macrophages permits SARS-CoV-2 entry, replication, and virion release. ACE2-expressing macrophages sense replicating virus to trigger pro-inflammatory and anti-viral programs that limit virus release. These combined findings resolve several controversies regarding macrophage-SARS-CoV-2 interactions and identify a signaling circuit by which macrophages sense SARS-CoV-2 cell entry and respond by restricting viral replication. One sentence summaryLack of macrophage ACE2 expression precludes SARS-CoV-2 entry and sensing, while ACE2-expressing macrophages sense intramacrophage SARS-CoV-2 replication to induce rapid anti-viral responses that limit new virion release.

immunology↗

bioRxiv2021

Muscle-specific Cavin4 interacts with Bin1 to promote T-tubule formation and stability in developing skeletal muscle

The cavin proteins are essential for caveola biogenesis and function. Here, we identify a role for the muscle-specific component, Cavin4, in skeletal muscle T-tubule development by analyzing two vertebrate systems: mouse and zebrafish. In both models Cavin4 localized to T-tubules and loss of Cavin4 resulted in aberrant T-tubule maturation. In zebrafish, which possess duplicated cavin4 paralogs, Cavin4b was shown to directly interact with the T-tubule-associated BAR domain protein, Bin1. Loss of both Cavin4a and Cavin4b caused aberrant accumulation of interconnected caveolae within the T-tubules, a fragmented T-tubule network enriched in Caveolin-3, and an impaired Ca2+ response upon mechanical stimulation. We propose a role for Cavin4 in remodeling the T-tubule membrane early in development by recycling caveolar components from the T-tubule to the sarcolemma. This generates a stable T-tubule domain lacking caveolae that is essential for T-tubule function.

cell biology↗

bioRxiv2020

A unified view of neighbour cell engagement during apoptotic cell extrusion.

Epithelia must eliminate apoptotic cells to preserve tissue barriers and prevent inflammation [1]. Several different mechanisms exist for apoptotic clearance, including efferocytosis [2, 3] and apical extrusion [4, 5]. We found that extrusion was the first-line response to apoptosis in cultured monolayers and in zebrafish epidermis. During extrusion, the apoptotic cell elicited active lamellipodial protrusions and assembly of a contractile extrusion ring in its neighbours. Depleting E-cadherin compromised both the contractile ring and extrusion, implying that a cadherin-dependent pathway allows apoptotic cells to engage their neighbours for extrusion. We identify RhoA as the cadherin-dependent signal in the neighbour cells and show that it is activated in response to contractile tension from the apoptotic cell. This mechanical stimulus is conveyed by a Myosin VI-dependent mechanotransduction pathway that is necessary both for extrusion and to preserve the epithelial barrier when apoptosis was stimulated. Earlier studies suggested that release of sphingosine-1-phosphate (S1P) from apoptotic cells might define where RhoA was activated. However, we found that although S1P is necessary for extrusion, its contribution does not require a localized source of S1P in the epithelium. We therefore propose a unified view of how RhoA is stimulated to engage neighbour cells for apoptotic extrusion. Here, tension-sensitive mechanotransduction is the proximate mechanism that activates RhoA specifically in the immediate neighbours of apoptotic cells, but this also must be primed by S1P in the tissue environment. Together, these elements provide a coincidence detection system that confers robustness on the extrusion response.

cell biology↗