How does cell size impact cellular homeostasis? Matthew is a Wellcome Trust CDA Fellow and Group Leader at the Centre for Cell Biology, where his group uses quantitative approaches in cell and molecular biology to understand how different cellular processes are rewired as cells grow and change their size.After studying Natural Sciences at the University of Cambridge, Matthew obtained his PhD in Sir Paul Nurse's lab (Francis Crick Institute), working on Cyclin-Cdk substrate phosphorylation dynamics. In 2017, he moved to Stanford as a postdoc with Jan Skotheim, where he used quantitative functional genomics approaches to address the long-standing question of how global transcriptional output is scaled with cell size. Matthew moved to Edinburgh in Autumn 2023 to establish his independent research group. Matthew Swaffer Swaffer Lab Website Lab members Dr. Carolina Martinez-Herraez, Simon Seliner, Luisa Hernandez-Goetz, Srinivash Muthuraman, Yuyang Miao, Adriana Cusi, Quang Huy Le & Aakansha Pal Research How does cell size impact gene expression, biosynthesis and cell function?The size of a cell is one of its most basic and fundamental properties. While the significance of cell size for cellular physiology has been appreciated for many decades, we still have a surprisingly poor understanding of the mechanisms that couple the inner molecular workings of the cell to its size.Core cellular processes must be coordinated with cell size to sustain a cell’s ability to grow and function optimally. For instance, protein and RNA amounts, as well as organelle volumes, increase continuously during the cell cycle in proportion to cell size, even though the template DNA genome does not (Figure A). This global scaling of macromolecules with size is critical as it ensures that the concentrations of enzymes and reactants are kept constant so that reactions and core cellular processes are maintained at a constant rate as cells grow and vary in size. As such, a major and long-standing question in cell biology has been: how is the production of macromolecules regulated to ensure this coupling with cell size?The Swaffer lab employ molecular and systems approaches to study how global gene expression, RNA processing, proteome homeostasis, cellular signalling and cell division are regulated as cells grow and increase in size. Addressing these questions requires us to build a more quantitative view of how the central dogma plays out in vivo, and this is one major theme of our work. To do this, we take an interdisciplinary approach that combines functional genomics, proteomics, imaging, and computational biology and utilise both yeast and mammalian cell lines as model systems. Image Figure Legend(A) Total RNA and protein amounts scale with cell size despite the template DNA genome only increasing discretely during S phase. (B) The equilibrium kinetics of limiting RNA polymerase II is responsible for a global transcriptional increase as cells grow and become larger. (C) The scaling of transcription is not directly proportional to cell size, and so an additional feedback mechanism is required to adjust mRNA stability in larger cells to ensure mRNA amounts scale directly with cell size. Recent and future researchWe have recently shown that the genome-binding equilibrium kinetics of RNA polymerase II drive a global increase in mRNA transcription as cells grow and increase in size (Swaffer et al., Cell, 2023)(Figure B). However, this scaling is not directly proportional to size, which led us to discover that mRNA decay rates are also modulated to stabilise the transcriptome of larger cells. This results in the proportional scaling of mRNA amounts with cell size and thereby ensures global mRNA concentration homeostasis (Figure C).These results raise several important questions about how cellular biosynthesis is coordinated with cell size that we plan to pursue. What are the molecular mechanisms that adjust mRNA turnover in larger cells? What are the limits on this balance between transcription and decay, and what are the consequences when such limits are reached? How do size-dependent changes in mRNA synthesis and turnover impact global proteome homeostasis? How does altered cell size impact other aspects of genome function, including chromatin compaction and organisation? How conserved are these mechanisms across species, and are similar processes at play to coordinate tRNA and rRNA production with the size-scaling of mRNA? Moreover, many diseases are known to be associated with altered cell size – especially cancer and ageing – and so we are interested in exploring how cell size scaling may contribute to these pathologies. Selected publications A. T. Lessenger, J. M. Skotheim, M. P. Swaffer*, J. L. Feldman*. Somatic polyploidy supports biosynthesis and tissue function by increasing transcriptional output. J Cell Biol, 224(3): e202403154 (2025)M. P. Swaffer, G. Marinov, H. Zheng, L. F. Valenzuela, C. Tsui, A. W. Jones, J. Greenwood, A. Kundaje, W. Greenleaf, R. Reyes-Lamothe, J. M. Skotheim. RNA polymerase II dynamics and mRNA stability feedback scale mRNA amounts with cell size. Cell, 8674(23)01128-5 (2023)S. Xie, M. Swaffer, J. M. Skotheim. Eukaryotic Cell Size Control and Its Relation to Biosynthesis and Senescence. Annu Rev Cell Dev Biol. (2022)M. C. Lanz, E. Zatulovskiy, M. P. Swaffer, L. Zhang, S. Zhang, D. S. You, G. K. Marinov, P. McAlpine, J. E. Elias, J. M. Skotheim. Increasing cell size remodels the proteome and promotes senescence. Molecular Cell, 82(17), 3255–3269.e8 (2022)M. P. Swaffer, J. Kim, D. Chandler-Brown, M. Langhinrichs, G. Marinov, W. Greenleaf, A. Kundaje, K. M. Schmoller, J. M. Skotheim. Size-independent mRNA synthesis and chromatin-based partitioning mechanisms generate and maintain constant amounts of protein per cell. Molecular Cell, 81(23), 4861–4875.e7 (2021) This article was published on 2026-04-23
