Biology subjects

MacRae, J.

Publications and source records attributed to MacRae, J..

5 recordsLinked to original sources

bioRxiv2026

Natural statistics of host odours predict species-specific olfactory behaviours in Drosophilids

Animals rely on olfaction to locate food, mates, and suitable habitats, yet natural odour environments contain thousands of volatile molecules, creating a high-dimensional sensory problem for both nervous systems and the researchers who study them 1-5. For example, a banana emits around 100 individual volatiles4,6. It remains unclear which components of complex odour blends animals have evolved to use as behavioural cues. Here, combining fieldwork, chemical and behavioural analyses, we show across multiple Drosophila species that behaviourally relevant cues can be predicted directly from the statistical structure of natural odour environments. Animals preferentially respond to components that are most distinctive within their natural host odour blends, and therefore most ecologically informative. These cues can be either major or minor blend components. Our results indicate that host-guided olfactory behaviours have evolved to exploit the statistical structure of natural odour environments by selectively targeting the most informative features of odour blends.

neuroscience↗

bioRxiv2025

Oncogenic RAS activity is linked to immune priming and adenosine-driven immune evasion in lung adenocarcinoma

Lung adenocarcinoma (LUAD) is a leading cause of cancer death worldwide, with RAS signalling as a key oncogenic driver. Although KRAS mutations have been linked to immune evasion in preclinical models, the relationship between RAS activity and tumour immunity or response to immunotherapy in patients remains unclear. Here, we applied our previously validated RAS84 transcriptional signature to stratify LUAD patient cohorts and dissect the immune landscape associated with RAS signalling. We report that tumours with elevated RAS activity exhibited features of immune priming, including increased immune infiltration, interferon response, and immune checkpoint gene expression, and showed improved progression-free survival in an independent cohort of patients treated with anti-PD-1. Yet, in both LUAD tumours and cell lines, RAS activity also correlated with elevated immunosuppressive interstitial adenosine mediated by transcriptional regulation of several components of the adenosinergic pathway. In orthotopic pre-clinical models of high-RAS activity lung tumours, blocking adenosine signalling delayed tumour growth and improved response to anti-PD-1 and KRAS inhibition, with a significant effect on innate immunity. This study reveals a dual role for RAS signalling in tumour progression, fostering a pro-immunogenic environment whilst simultaneously dampening anti-tumoural immunity via mechanisms including extracellular adenosine accumulation. Stratifying patients based on RAS transcriptional activity, rather than genetic alterations alone, could inform immunotherapy strategies and improve clinical outcomes.

cancer biology↗

bioRxiv2023

GOT1 primes the cellular response to hypoxia by supporting glycolysis and HIF1α stabilisation

Adaptation to chronic hypoxia occurs through changes in protein expression, which are controlled by hypoxia inducible factor 1a (HIF1) and are necessary for cancer cell survival. However, the mechanisms that enable cancer cells to adapt in early hypoxia, prior to full activation of HIF1, remain poorly understood. Here we show that aspartate transaminase 1 (GOT1), which supports NAD+ production by malate dehydrogenase 1 (MDH1), is required, in addition to reserve lactate dehydrogenase (LDH) capacity, for the HIF1-independent increase in glycolysis we observe early upon exposure of cells to hypoxia. Additionally, GOT1 maintains low -ketoglutarate levels, thereby limiting prolyl hydroxylase activity to promote HIF1 stabilisation in early hypoxia and robust HIF1 target gene expression in later hypoxia. Our findings reveal that, in normoxia, GOT1 maintains cells in a primed state and ready to support increased glycolysis and HIF1 stabilisation upon oxygen limitation, until other adaptive processes that require more time, are fully established.

cancer biology↗

bioRxiv2021

PHGDH is required for germinal center formation and is a therapeutic target in MYC-driven lymphoma

The synthesis of serine from glucose is a key metabolic pathway supporting cellular proliferation in healthy and malignant cells. Despite this, the role that this aspect of metabolism plays in germinal center biology and pathology is not known. Here, we performed a comprehensive characterization of the role of the serine synthesis pathway in germinal center B cells and lymphomas derived from these cells. We demonstrate that upregulation of a functional serine synthesis pathway is a metabolic hallmark of B-cell activation and the germinal center reaction. Inhibition of phosphoglycerate dehydrogenase (PHGDH), the first and rate limiting enzyme in this pathway, leads to defective germinal formation and impaired high-affinity antibody production. In addition, overexpression of enzymes involved in serine synthesis is a characteristic of germinal center B-cell derived lymphomas, with high levels of expression being predictive of reduced overall survival in diffuse large B cell lymphoma. Inhibition of PHGDH induces apoptosis in lymphoma cells reducing disease progression. These findings establish PHGDH as a critical player in humoral immunity and a clinically relevant target in lymphoma.

immunology↗

bioRxiv2019

Perturbation of the gut microbiota by antibiotics results in accelerated breast tumour growth and metabolic dysregulation

BackgroundBreast cancer is the second most prevalent cancer worldwide with around 1.7 million new cases diagnosed every year. Whilst prognosis is generally favourable in early stages, this worsens significantly in advanced disease. Therefore, it is pertinent to focus on mitigating factors that may slow growth or progression. Recently, the gut microbiome has been implicated in a wide-range of roles in tumour biology. Through modulation of immunity, the gut microbiota can improve the efficacy of several immunotherapies. However, despite the prevalence of breast cancer, there is still a lack of microbiota studies in this field, including exploring the influence of external microbiome-modulating factors such as antibiotics. We describe herein how disruption of the gut microbiota via antibiotics may be detrimental to patient outcomes through acceleration of tumour growth. ResultsSupplementing animals with a cocktail of antibiotics leads to gut microbiota alterations and is accompanied by significant acceleration of tumour growth. Surprisingly, and distinct from previous microbiome-tumour studies, the mechanism driving these effects do not appear to be due to gross immunological changes. Analysis of intratumoural immune cell populations and cytokine production are not affected by antibiotic administration. Through global tumour transcriptomics, we have uncovered dysregulated gene expression networks relating to protein and lipid metabolism that are correlated with accelerated tumour growth. Fecal metabolomics revealed a reduction of the microbial-derived short-chain fatty acid butyrate that may contribute to accelerated tumour growth. Finally, through use of a routinely administered antibiotic in breast cancer patients, Cephalexin, we have shown that tumour growth is also significantly affected. Metataxanomic sequencing and analysis highlighted significant antibiotic-associated reductions in the butyrate producing genera Odoribacter and Anaeotruncus, and increased abundance of Bacteroides. ConclusionsOur data indicate that perturbation of the microbiota by antibiotics may have negative impacts on breast cancer patient outcomes. This is of importance as antibiotics are regularly prescribed to breast cancer patients undergoing mastectomy or breast reconstruction. We have also shown that the metabolic impact of disruption to the microbiome should be considered alongside the potent immunological effects. We believe our work lays the foundation for improving the use of antibiotics in patients, and with further investigation could potentially inform clinical practice.

cancer biology↗