Biology subjects

Scott, N. A.

Publications and source records attributed to Scott, N. A..

4 recordsLinked to original sources

bioRxiv2026

Derlin-mediated ERAD of lipid regulator ORMDL3 safeguards mitochondrial function

Mammalian Derlin proteins (Derlin-1, Derlin-2, and Derlin-3) are conserved components of the endoplasmic reticulum-associated degradation (ERAD) machinery that mediate the retrotranslocation and proteasomal degradation of misfolded ER-resident proteins. However, their paralog-specific contributions to cellular homeostasis remain poorly understood. Here, we show that Derlin deficiency disrupts mitochondrial architecture and results in mitochondrial fragmentation and tightening of ER-mitochondria contact sites (MERCs) in HEK293 cells. Mechanistically, we identify ORMDL proteins, evolutionarily conserved negative regulators of sphingolipid biosynthesis, as substrates of Derlin-2- and Derlin-3-dependent ERAD. Derlin deficiency leads to selective accumulation of ORMDL3 and its dose-dependent enrichment at MERCs, where it drives mitochondrial dysfunction in respiration and calcium handling. Reducing ORMDL3 levels restores mitochondrial function, establishing ORMDL3 as a key effector downstream of Derlin loss. Our work establishes ERAD as a critical mechanism of protein quantity control that safeguards organelle homeostasis by preventing aberrant accumulation and mislocalization of ER clients at inter-organelle contact sites. Given that ORMDL family members are central regulators of sphingolipid metabolism and are genetically linked to inflammation, cancer, asthma, inflammatory bowel disease, type 1 and type 2 diabetes, multiple sclerosis, obesity, and nonalcoholic fatty liver disease, these findings connect ERAD-dependent spatial control to sphingolipid homeostasis and a broad spectrum of human pathologies.

cell biology↗

bioRxiv2024

SOX9-regulated matrix proteins predict poor outcomes in patients with COVID-19 and pulmonary fibrosis

Pulmonary fibrosis is an increasing and major cause of death worldwide. Understanding the cellular and molecular mechanisms underlying the pathophysiology of lung fibrosis may lead to urgently needed diagnostic and prognostic strategies for the disease. SOX9 is a core transcription factor that has been associated with fibrotic disease, however its role and regulation in acute lung injury and/or fibrosis have not been fully defined. In this study we apply a hypothesis based approach to uncover unique SOX9-protein signatures associated with both acute lung injury and fibrotic progression. Using in vivo models of lung injury in the presence or absence of SOX9, our study shows SOX9 is essential to the damage associated response of alveolar epithelial cells from an early time-point in lung injury. In parallel, as disease progresses, SOX9 is responsible for regulating tissue damaging ECM production from pro-fibrotic fibroblasts. In determining the in vivo role of SOX9 we identified secreted ECM components downstream of SOX9 as markers of acute lung injury and fibrosis. To underscore the translational potential of our SOX9-regulated markers, we analysed serum samples from acute COVID19, post COVID19 and idiopathic pulmonary fibrosis (IPF) patient cohorts. Our hypothesis driven SOX9-panels showed significant capability in all cohorts at identifying patients who had poor disease outcomes. This study shows that SOX9 is functionally critical to disease in acute lung injury and pulmonary fibrosis and its regulated pathways have diagnostic, prognostic and therapeutic potential in both COVID19 and IPF disease.

molecular biology↗

bioRxiv2021

Macrophages in the uterus are functionally specialised and continually replenished from the circulation

Macrophages are innate immune cells that fight infection but also regulate tissue regeneration and remodelling. In the uterus, although tissue remodelling is essential for establishment and maintenance of pregnancy, the specialisation of macrophages is not well characterised compared to other mucosal tissues. Here we show that uterine macrophages are functionally specialised, expressing multiple markers of alternative activation associated with tissue remodelling and repair, and responding more highly to the type 2 cytokine IL-4 than other mucosal tissue macrophages. Uterine macrophages were continuously replenished from circulating bone marrow-derived CCR2+ monocytes that fluctuated dramatically in number throughout the reproductive cycle, and had properties distinct from the macrophages that they became, including differential responses to microbial stimulation. Importantly, many of these properties of uterine monocytes and macrophages were conserved between mice and humans. These findings further our understanding of immune regulation of uterine tissue integrity and have important implications for differences in immune responses to infections at different phases of the reproductive cycle. SUMMARYUterine macrophages are specialised, alternatively activated cells that are replenished from circulating bone marrow-derived monocytes. Monocyte and macrophage properties fluctuate markedly throughout the reproductive cycle, with many features conserved between mice and humans, and exhibiting differential responses to microbial stimulation.

immunology↗

bioRxiv2021

Macrophage metabolism in the intestine is compartment-specific and regulated by the microbiota

Intestinal macrophages play a vital role in the maintenance of gut homeostasis through signals derived from the microbiota. We previously demonstrated that microbial-derived metabolites can shape the metabolic functions of macrophages. Here, we show that antibiotic-induced disruption of the intestinal microbiota dramatically alters both the local metabolite environment, and the metabolic functions of macrophages in the colon. Broad-spectrum antibiotic administration in mice increased expression of the large neutral amino acid transporter and accordingly, amino acid uptake. Subsequently, antibiotic administration enhanced the metabolic functions of colonic macrophages, increasing phosphorylation of components of mammalian/mechanistic target of rapamycin (mTOR) signalling pathways, increasing expression of genes involved in glycolysis and oxidative phosphorylation (OXPHOS), increasing mitochondrial function and increased levels of ECAR and OCR as a direct measure of glycolysis and OXPHOS. Small bowel macrophages were less metabolically active than in the colon, with macrophage metabolism being independent of the microbiota. Finally, we reveal tissue resident Tim4+ CD4+ macrophages exhibit enhanced fatty acid uptake alongside reduced fatty acid synthesis compared to their recruited counterparts. Thus the microbiota shapes gut macrophage metabolism in a compartment-specific manner, with important implications for functions when monocyte recruitment and macrophage differentiation.

immunology↗