A Reliable System for Quantitative G-Protein Activation Imaging in Cancer Cells.

Fluorescence resonance energy transfer (FRET) biosensors have proven to be an indispensable tool in cell biology and, more specifically, in the study of G-protein signalling. The best method of measuring the activation status or FRET state of a biosensor is often fluorescence lifetime imaging microscopy (FLIM), as it does away with many disadvantages inherent to fluorescence intensity-based methods and is easily quantitated. Despite the significant potential, there is a lack of reliable FLIM-FRET biosensors, and the data processing and analysis workflows reported previously face reproducibility challenges. Here, we established a system in live primary mouse pancreatic ductal adenocarcinoma cells, where we can detect the activation of an mNeonGreen-Gαi3-mCherry-Gγ2 biosensor through the lysophosphatidic acid receptor (LPAR) with 2-photon time-correlated single-photon counting (TCSPC) FLIM. This combination gave a superior signal to the commonly used mTurquoise2-mVenus G-protein biosensor. This system has potential as a platform for drug screening, or to answer basic cell biology questions in the field of G-protein signalling.

Sinking while you swim: A dual role for CCR7 in leukocyte migration.

The CCR7 receptor allows dendritic cells to sense the chemokine CCL19. It also depletes CCL19 from the environment by endocytosis, leading to local gradients that can steer cells accurately and robustly through tissues, even over long distances (see related Research Article by Alanko et al.).

Working at the interface of physics and biology: An early career researcher perspective.

We are a network of Early Career Researchers (ECRs) and a Project Manager who are working on UKRI's "Physics of Life" grants which aim to merge ideas and techniques predominantly used in physics and apply them to biological questions. We have been collaborating since early 2021 to share research, experiences, and provide peer to peer support. Interdisciplinary projects are known for presenting challenges, bringing together disparate subjects and people with not only different knowledge bases, methods, and equipment but also varying ways of working and common languages. This has been the subject of commentary by researchers and funders from a management perspective, and we wanted to add to this discourse, using our experience to share the lessons and challenges we have encountered, from an ECR perspective.

MYC sensitises cells to apoptosis by driving energetic demand.

The MYC oncogene is a potent driver of growth and proliferation but also sensitises cells to apoptosis, which limits its oncogenic potential. MYC induces several biosynthetic programmes and primary cells overexpressing MYC are highly sensitive to glutamine withdrawal suggesting that MYC-induced sensitisation to apoptosis may be due to imbalance of metabolic/energetic supply and demand. Here we show that MYC elevates global transcription and translation, even in the absence of glutamine, revealing metabolic demand without corresponding supply. Glutamine withdrawal from MRC-5 fibroblasts depletes key tricarboxylic acid (TCA) cycle metabolites and, in combination with MYC activation, leads to AMP accumulation and nucleotide catabolism indicative of energetic stress. Further analyses reveal that glutamine supports viability through TCA cycle energetics rather than asparagine biosynthesis and that TCA cycle inhibition confers tumour suppression on MYC-driven lymphoma in vivo. In summary, glutamine supports the viability of MYC-overexpressing cells through an energetic rather than a biosynthetic mechanism.