Biology subjects

Lamond, A. I.

Publications and source records attributed to Lamond, A. I..

At least 19 recordsLinked to original sources

bioRxiv2026

CysNet: Theorem constrained inference of cysteine redox proteoform states from bottom-up mass spectrometry data

Here, we present CysNet, a theorem-constrained method designed to infer cysteine redox proteoforms, i.e.,oxiforms, from bottom-up, mass spectrometry (MS)-based proteomic data. This overcomes limitations with previous MS redox proteomic approaches, which can quantify residue-resolved cysteine redox states, but leave distinct oxiforms unresolved. CysNet treats each residue-resolved oxidation value as a binary redox-coordinate marginal, enabling theorem-constrained inference of the oxiforms that are necessary, impossible or bounded within the compatible protein-group ensemble. This collapses the vast theoretically possible set of oxiform states to a finite set of allowed values by extracting existence and exclusion constraints from the data, despite the incomplete proteome coverage typical for bottom-up MS datasets. Using CysNet to analyse human induced pluripotent stem cell lines (~6,300 cysteine-containing protein groups, ~22% cysteine coverage), resolved 519 exact oxiforms, inferring 7,000 oxiforms per line. Quantitatively, CysNet bounded the oxiform content to 6.36-8.24 x 1012 protein copies, corresponding to 14-19% of the measured cysteine proteome. These data define the deepest oxiform survey recorded. CysNet revealed a latent structural layer in redox variation between the cell lines, distinguishing changes in oxiform identity (composition) from changes in oxiform weighting (intensity). Hence, CysNet moves bottom-up redox proteomics beyond isolated site-level cataloguing by reconstructing copy-number-weighted oxiform maps, providing a scalable route to deep oxiform information from peptide-level data.

biochemistry↗

bioRxiv2026

ReCap enables deep, copy number-scaled cysteine redox proteomics with minimal exogenous oxidation

Cysteine oxidation analyses require the preservation of the redox state present at harvest and quantitative scaling to relate oxidation to protein copy numbers, rather than only providing fractional oxidation data. Here, we present ReCap, a Redox Capture workflow combining Oxi-DIA, an enrichment-free isotope-encoded DIA workflow, with Oxi-Stop, a simple oxygen-exclusion strategy for cryopreserved tissue. In mouse brains, Oxi-DIA quantified 17,809 cysteine sites belonging to 6,085 protein groups in every sample, enabling matched measurements of residue-resolved oxidation and protein abundance. Atmospheric oxygen exposure during 14 days of cryopreservation distorted the measured cysteine redox state. The resultant increase of an estimated 5.3176 x 1011 {micro}g-1 oxidised cysteine molecules was mitigated by Oxi-Stop, which minimised exogenous oxidation during cryopreservation. Copy-number scaling altered the interpretation of cysteine oxidation values. Although cysteine oxidation was detected across 2,371 sites and 1,439 proteins, 20 sites on abundant proteins accounted for 44% of the oxidised signal. ReCap advances redox proteomics from providing a site catalogue into a biologically weighted map of redox information, revealing cysteine oxidation as a sparse, ordered and quantitatively concentrated signal.

biochemistry↗

bioRxiv2025

Differential contribution of the RNA recognition motifs to SRSF1 protein interaction network

The protein SRSF1, initially identified as a splicing factor, is currently known to participate in a variety of cellular processes. However, its role and regulatory mechanisms in these processes remain incompletely understood. Using a SILAC proteomic approach, we have characterised the SRSF1 interactome, thereby identifying multiple diverse protein interaction partners of SRSF1 and the molecular complexes with which it is associated. Given that the RNA-binding ability of SRSF1 is necessary for many of its activities, we extended the analysis of the SRSF1 interactome to compare the wild type protein against two site-specific SRSF1 variants, bearing mutations in each of its two RNA recognition motifs (RRMs). The first mutation disrupted the canonical RRM (RRM1), while the second affected the pseudo-RRM (RRM2). Interestingly, the data show clear differences between the SRSF1 interacting proteins, depending on the functional status of each RRM domain. In particular, a functional RRM1 was critical for maintaining interactions with multiple partners, especially those involved in translation-related processes, showing a far greater loss of interactions upon mutation than RRM2. This study provides valuable new insights into the broader cellular roles and interaction landscape of SRSF1.

molecular biology↗

bioRxiv2025

CaMKII-RNMT axis directs activity-dependent control of RNA dynamics in neurons

In neurons, mRNAs are transported into axons and dendrites for local translation at synapses. Diverse proteins support the transport of specific mRNAs, however, mechanisms co-ordinating mRNA translocation are unclear. We report that that CaMKII (Ca2+/calmodulin-dependent protein kinase II) is a key regulator of RNA dynamics through activity-dependent phosphorylation of the RNA cap guanine-7 methyltransferase, RNMT. Following RNA cap methylation in the nucleus, RNMT is retained on specific mRNAs. On stimulation, RNMT translocates into the cytoplasm, increasing levels of locally translated mRNAs. In the cytoplasm, CaMKII phosphorylates RNMT Thr317 on the active site, which inhibits methyltransferase activity and targets RNMT for degradation, thus limiting cytoplasmic RNMT function. RNMT mutants protected from CaMKII-dependent degradation increase locally translated, cytoplasmic mRNAs and accelerate neuronal morphogenesis. RNMT Thr317 phospho-mimic co-ordinately decreases locally translated mRNAs in the cytoplasm and reduces differentiation. The CaMKII-RNMT relationship links neuronal activity to the spatial regulation of gene expression in neurons. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=126 SRC="FIGDIR/small/685591v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@b97c4borg.highwire.dtl.DTLVardef@18f38eaorg.highwire.dtl.DTLVardef@1e1bcb0org.highwire.dtl.DTLVardef@12ac7c7_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2025

PHD1-dependent hydroxylation of RepoMan (CDCA2) on P604 modulates the control of mitotic progression

Prolyl-hydroxylases (PHDs) are oxygen sensing enzymes that mediate the hydroxylation of proline residues. In mammals, three PHD isoforms (PHD1-3) are responsible for proline hydroxylation of Hypoxia Inducible Factor (HIF) alpha, a key regulator of the hypoxia response. In the accompanying paper (Jiang et. al., 2025) we report development of a mass spectrometry-based method to reliably identify proline hydroxylation (OH-Pro) sites on proteins and use this to identify a PHD-dependent OH-Pro modification at Pro604 on the protein RepoMan (CDCA2), a regulatory subunit for protein phosphatase PP1{gamma}, with important roles in mitotic progression and cell viability. Here, we investigate the functional significance of hydroxylation of RepoMan at P604. During M phase, the PP1-RepoMan complex dephosphorylates Thr3 of Histone H3 (H3T3) on chromosomes arms to ensure the correct localisation of the chromosomal passenger complex (CPC) at centromeres. We show that siRNA depletion of PHD1, but not PHD2, increases H3T3 phosphorylation in prometaphase-arrested cells. In cells depleted of endogenous RepoMan, exogenous expression of wild type RepoMan, but not a RepoMan P604A mutant, restored normal H3T3 phosphorylation localisation in prometaphase arrested cells. RepoMan P604 is located proximal to the Short Linear Motifs (SLiMs) that function as binding sites for the serine/threonine Protein Phosphatase 2A (PP2A). The interaction of RepoMan and PP2A-B56{gamma} is reduced in cells expressing RepoMan P604A. Moreover, analyses in both fixed and live cells released from a prometaphase arrest, show that expression of the RepoMan P604A mutant delays completion of mitosis, results in defects in chromosome alignment and segregation and increases levels of cell death. These data support a role for PHD1-mediated prolyl hydroxylation in controlling progression through mitosis, acting, at least in part, via hydroxylation of RepoMan at P604 regulating the interaction of RepoMan with PP2A during chromosome alignment and thereby controlling the levels of Histone H3 phosphorylation at Thr3.

cell biology↗

bioRxiv2024

Assembly of mTORC3 involves binding of ETV7 to two separate sequences in the mTOR kinase domain.

mTOR plays a crucial role in cell growth by controlling ribosome biogenesis, metabolism, autophagy, mRNA translation, and cytoskeleton organization. It is a serine/threonine kinase that is part of two distinct extensively described protein complexes, mTORC1 and mTORC2. We have identified a rapamycin resistant mTOR complex, called mTORC3, which is different from the canonical mTORC1 and mTORC2 complexes in that it does not contain the Raptor, Rictor, or mLST8 mTORC1 / 2 components. mTORC3 phosphorylates mTORC1 and mTORC2 targets and contains the ETS transcription factor ETV7, which binds to mTOR and is essential for mTORC3 assembly in the cytoplasm. Tumor cells that assemble mTORC3 have a proliferative advantage and become resistant to rapamycin, indicating that inhibiting mTORC3 may have a therapeutic impact on cancer. Here, we investigate which domains or amino acid residues of ETV7 and mTOR are involved in their mutual binding. We found that the mTOR FRB and LBE sequences in the kinase domain interact with the pointed (PNT) and ETS domains of ETV7, respectively. We also found that forced expression of the mTOR FRB domain in the mTORC3 expressing, rapamycin-resistant cell line Karpas-299 out competes mTOR for ETV7 binding and renders these cells rapamycin-sensitive in vivo. Our data provide useful information for the development of molecules that prevent the assembly of mTORC3, which may have therapeutic value in the treatment of mTORC3 positive cancer.

cancer biology↗

bioRxiv2023

Systematic characterization of site-specific proline hydroxylation using hydrophilic interaction chromatography and mass spectrometry

We have developed a robust workflow for the identification of proline hydroxylation sites in proteins, using a combination of hydrophilic interaction chromatography (HILIC) enrichment and high-resolution nano-Liquid Chromatography-Mass Spectrometry (LC-MS) together with refining and filtering parameters during data analysis. Using this approach, we have combined data from cell lines treated with either the prolyl hydroxylase (PHD) inhibitor, Roxadustat (FG-4592), or with the proteasome inhibitor MG-132, or with a DMSO control, to identify a total of 4,993 and 3,247 proline hydroxylation sites, respectively, in HEK293 and RCC4 cells. A subset of 1,954 (HEK293) and 1,253 (RCC4) non-collagen proline hydroxylation sites with high confidence were inhibited by FG-4592 treatment. Features characteristic of proline hydroxylated peptides were identified, which were consistent between the HEK293 and RCC4 datasets. The more hydrophilic HILIC fractions were enriched in peptides containing hydroxylated proline residues, which showed characteristic differences in charge and mass distribution, as compared with either unmodified, or oxidised peptides. Furthermore, we discovered that the intensity of the diagnostic hydroxyproline immonium ion was dependent upon parameters including the MS collision energy setting, parent peptide concentration and the sequence of amino acids adjacent to the modified proline. We show using synthetic peptides that a combination of retention time in LC and optimised MS parameter settings allows reliable identification of proline hydroxylation sites in peptides, even when multiple prolines residues are present. Focussing on proteins in which newly identified proline hydroxylation sites were inhibited by the pan-PHD inhibitor, FG-4592, showed enrichment for proteins involved in metabolism of RNA, mRNA splicing and cell cycle regulation, including the protein phosphatase 1 regulatory subunit, Repo-Man (CDCA2). We show that Repo-Man is hydroxylated at P604 and in the accompanying study by Druker et al. 1, we present a combination of cellular and biochemical evidence that hydroxylation of Repo-Man at P604 is important for its function in controlling mitotic progression.

biochemistry↗

bioRxiv2023

Screening for variable drug responses using human iPSC cohorts

We have developed a laboratory-based drug screening platform that uses a cohort of human induced pluripotent stem cell (hiPSC) lines, derived from different donors, to predict variable drug responses of potential clinical relevance. This builds on recent findings that pluripotent hiPSC lines express a broad repertoire of gene transcripts and proteins, whose expression levels reflect the genetic identity of the donor. We demonstrate that a cohort of hiPSC lines from different donors can be screened efficiently in their pluripotent state, using high-throughput Cell Painting assays. Variable phenotypic responses between hiPSC lines were detected with a wide range of clinically approved drugs, in use across multiple disease areas. Furthermore, information on mechanisms of drug-cell interactions underlying the observed variable responses was derived by using quantitative proteomic analysis to compare sets of hiPSC lines that had been stratified objectively, based upon variable response, Cell Painting data. We propose that information derived from comparative drug screening, using curated libraries of hiPSC lines from different donors, can help to improve the delivery of safe new drugs suitable for a broad range of genetic backgrounds and sexual diversity within human populations.

cell biology↗

bioRxiv2023

Transcription promotes the restoration of chromatin following DNA replication.

DNA replication results in the transient eviction of nucleosomes, RNAPII and transcription regulators. How chromatin organization is duplicated on the two daughter strands is a central question in epigenetics. In mammals, transcription restarts on newly replicated DNA within a couple of hours, promoting chromatin accessibility. However, the role of transcription in the restoration of other chromatin determinants following DNA replication remains unclear. Here we have monitored protein re-association to newly replicated DNA upon inhibition of transcription using iPOND coupled to quantitative mass spectrometry. We show that nucleosome assembly and the re-establishment of most histone modifications are uncoupled from transcription restart. However, upon transcription inhibition, the re-association of many proteins was altered, including ATP-dependent remodellers, transcription regulators, the histone variant H2A.Z, histone modifiers as well as the restoration of H3.3K36me2. Finally, transcription also provoked the recruitment of several DNA repair proteins, revealing that transcription promotes chromatin reestablishment post-replication but is also a potential source of genotoxic stress.

molecular biology↗

bioRxiv2022

Native size exclusion chromatography-based mass spectrometry (SEC-MS) identifies novel components of the Heat Shock Protein 90-dependent proteome

The molecular chaperone heat shock protein 90 (HSP90) works in concert with co-chaperones to stabilize its client proteins, which include multiple drivers of oncogenesis and malignant progression. Pharmacologic inhibitors of HSP90 have been observed to exert a wide range of effects on the proteome, including depletion of client proteins, induction of heat shock proteins, dissociation of co-chaperones from HSP90, disruption of client protein signaling networks, and recruitment of the protein ubiquitylation and degradation machinery--suggesting widespread remodeling of cellular protein complexes. However, proteomics studies to date have focused on inhibitor-induced changes in total protein levels, often overlooking protein complex alterations. Here, we use size-exclusion chromatography in combination with mass spectrometry (SEC-MS) to characterize the changes in native protein complexes following treatment with the HSP90 inhibitor tanespimycin (17-AAG) in the HT29 colon adenocarcinoma cell line. After confirming the signature cellular response to HSP90 inhibition (e.g., induction of heat shock proteins, decreased total levels of client proteins), we were surprised to find only modest perturbations to the global distribution of protein elution profiles in inhibitor-treated cells. Similarly, co-chaperones that co-eluted with HSP90 displayed no clear difference between control and treated conditions. However, two distinct analysis strategies identified multiple inhibitor-induced changes, including several known components of the HSP90 proteome, as well as numerous proteins and protein complexes with no previous links to HSP90. We present this dataset as a resource for the HSP90, proteostasis, and cancer communities (https://www.bioinformatics.babraham.ac.uk/shiny/HSP90/SEC-MS/), laying the groundwork for future mechanistic and therapeutic studies related to HSP90 pharmacology. Data are available via ProteomeXchange with identifier PXD033459.

biochemistry↗

bioRxiv2022

Identification of putative reader proteins of 5-methylcytosine and its derivatives in Caenorhabditis elegans RNA

Methylation of carbon-5 of cytosines (m5C) is a post-transcriptional nucleotide modification of RNA with widespread distribution across organisms. m5C has been shown to participate in mRNA transport and maintain mRNA stability through its recognition by the reader proteins ALYREF and YBX1, respectively. We recently showed that m5C is required for Caenorhabditis elegans development and fertility under heat stress. To contribute to the understanding of how m5C and its oxidative derivatives mediate their functions, we developed RNA baits bearing modified cytosines in diverse structural contexts to pulldown potential readers in C. elegans. Our mass spectrometry analyses reveal unique binding proteins for each of the modifications. We validate our dataset by demonstrating that the nematode ALYREF homologues ALY-1 and ALY-2 preferentially bind m5C in vitro. The dataset presented here serves as an important scientific resource that will support the discovery of new functions of m5C and its derivatives.

biochemistry↗

bioRxiv2021

A quantitative comparison of human embryonic and induced stem cell proteomes

Human induced pluripotent stem cells (hiPSCs) have great potential to be used as alternatives to embryonic stem cells (hESCs) in regenerative medicine and disease modelling, thereby avoiding many of the ethical issues arising from the use of embryo-derived cells. However, despite clear similarities between the two cell types, it is likely they are not identical. In this study, we characterise the proteomes of multiple hiPSC and hESC lines derived from independent donors. We find that while hESCs and hiPSCs express a near identical set of proteins, they show consistent quantitative differences in the expression levels of a wide subset of proteins. hiPSCs have increased total protein content, while maintaining a comparable cell cycle profile to hESCs. The proteomic data show hiPSCs have significantly increased abundance of vital cytoplasmic and mitochondrial proteins required to sustain high growth rates, including nutrient transporters and metabolic proteins, which correlated with phenotypic differences between hiPSCs and hESCs. Thus, higher levels of glutamine transporters correlated with increased glutamine uptake, while higher levels of proteins involved in lipid synthesis correlated with increased lipid droplet formation. Some of the biggest metabolic changes were seen in proteins involved in mitochondrial metabolism, with corresponding enhanced mitochondrial potential, shown experimentally using high-resolution respirometry. hiPSCs also produced higher levels of secreted proteins, including ECM components and growth factors, some with known tumorigenic properties, as well as proteins involved in the inhibition of the immune system. Our data indicate that reprogramming of human fibroblasts to iPSCs effectively restores protein expression in cell nuclei to a state comparable to hESCs, but does not similarly restore the profile of cytoplasmic and mitochondrial proteins, with consequences for cell phenotypes affecting growth and metabolism. The data improve understanding of the molecular differences between induced and embryonic stem cells, with implications for potential risks and benefits for their use in future disease modelling and therapeutic applications.

biochemistry↗

bioRxiv2021

Nrf2 is a central regulator of the metabolic landscape in macrophages and finetunes their inflammatory response

To overcome oxidative, inflammatory, and metabolic stress, cells have evolved networks of cytoprotective proteins controlled by nuclear factor erythroid 2 p45-related factor 2 (Nrf2) and its main negative regulator the Kelch-like ECH associated protein 1 (Keap1). Here, we used high-resolution mass-spectrometry to characterize the proteomes of macrophages with genetically altered Nrf2 status. Our analysis revealed significant differences among the genotypes in cellular metabolism and redox homeostasis, which we validated with respirometry and metabolomics, as well as in anti-viral immune pathways and the cell cycle. Nrf2 status significantly affected the proteome following lipopolysaccharide (LPS) stimulation, with alterations in redox, carbohydrate and lipid metabolism, and innate immunity observed. Of note, Nrf2 activation was found to promote mitochondrial fusion in inflammatory macrophages. The Keap1 inhibitor, 4-octyl itaconate (4-OI), a derivative of the mitochondrial immunometabolite itaconate, remodeled the inflammatory macrophage proteome, increasing redox and suppressing anti-viral immune effectors in a Nrf2-dependent manner. These data suggest that Nrf2 activation facilitates metabolic reprogramming and mitochondrial adaptation, and finetunes the innate immune response in macrophages. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=121 SRC="FIGDIR/small/456204v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1f5bbb8org.highwire.dtl.DTLVardef@1f7311dorg.highwire.dtl.DTLVardef@1b9722forg.highwire.dtl.DTLVardef@1f777d4_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIFirst high-resolution proteome of macrophages with genetically altered Nrf2 status C_LIO_LINrf2 is key regulator of macrophage redox and intermediary metabolism C_LIO_LINrf2 finetunes the inflammatory response suppressing anti-viral immune and cytokine effectors, whilst promoting T cell activation factors C_LIO_LINrf2 regulates mitochondrial adaptation in inflammatory macrophages promoting the formation of a fused network C_LIO_LI4-octyl itaconate (4-OI) suppresses anti-viral immune effectors in inflammatory macrophages in a Nrf2-dependent manner C_LI

immunology↗

bioRxiv2021

Tissue environment, not ontogeny, defines intestinal intraepithelial T lymphocytes

Tissue-resident intestinal intraepithelial T lymphocytes (T-IEL) patrol the gut and have important roles in regulating intestinal homeostasis. T-IEL include both induced T-IEL, derived from systemic antigen-experienced lymphocytes, and natural IEL, which are developmentally targeted to the intestine. While the processes driving T-IEL development have been elucidated, the precise roles of the different subsets and the processes driving activation and regulation of these cells remain unclear. To gain functional insights into these enigmatic cells, we used high-resolution, quantitative mass spectrometry to investigate the proteomic landscape of the main T-IEL populations in the gut. Comparing the proteomes of induced T-IEL and natural T-IEL subsets, with naive CD8+ T cells from lymph nodes exposes the dominant effect of the gut environment over ontogeny on T-IEL phenotypes. Analyses of protein copy numbers of >7000 proteins in T-IEL reveal skewing of the cell surface repertoire towards epithelial interactions and checkpoint receptors; strong suppression of the metabolic machinery indicating a high energy barrier to functional activation; and changes in T cell antigen receptor signalling pathways reminiscent of chronically activated T cells. These novel findings illustrate how multiple input signals need to be integrated to regulate T-IEL function.

immunology↗

bioRxiv2020

Erosion of human X chromosome inactivation alters proteome expression from genes across the X chromosome and all autosomes

X chromosome inactivation (XCI) is a dosage compensation mechanism in female mammals whereby genes from one X chromosome are repressed. Analysis of human induced pluripotent stem cell (iPSC) lines using proteomics, RNAseq and polysome profiling showed a major change in the proteome upon XCI erosion. This resulted in amplified RNA and protein expression from X-linked genes. However, increased protein expression was also detected from autosomal genes without a corresponding mRNA increase, altering the protein-RNA correlation between genes on the X chromosome and autosomes. Eroded iPSC lines display ~13% increase in cell protein content, along with increased expression of ribosomal proteins, ribosome biogenesis and translation factors. They also showed significantly increased levels of active polysomes within the eroded lines. We conclude that erosion of XCI causes a major remodelling of the proteome, with translational mechanisms affecting the expression of a much wider range of proteins and disease-linked loci than previously realised.

biochemistry↗

bioRxiv2019

Direct interaction of PIWI and DEPS-1 is essential for piRNA function and condensate ultrastructure in Caenorhabditis elegans

Membraneless organelles are platforms for many aspects of RNA biology including small non-coding RNA (ncRNA) mediated gene silencing. How small ncRNAs utilise phase separated environments for their function is unclear. To address this question, we investigated how the PIWI-interacting RNA (piRNA) pathway engages with the membraneless organelle P granule in Caenorhabditis elegans. Proteomic analysis of the PIWI protein PRG-1 revealed an interaction with the constitutive P granule protein DEPS-1. Furthermore we identified a novel motif on DEPS-1, PBS, which interacts directly with the Piwi domain of PRG-1. This protein complex forms intertwining ultrastructures to build elongated condensates in vivo. These sub-organelle ultrastructures depend on the Piwi-interacting motif of DEPS-1 and mediate piRNA function. Additionally, we identify a novel interactor of DEPS-1, EDG-1, which is required for DEPS-1 condensates to form correctly. We show that DEPS-1 is not required for piRNA biogenesis but piRNA function: deps-1 mutants fail to produce the secondary endo-siRNAs required for the silencing of piRNA targets. Our study reveals how specific protein-protein interactions drive the spatial organisation and function of small RNA pathways within membraneless organelles.

cell biology↗

bioRxiv2018

Cyclin A triggers Mitosis either via Greatwall or Cyclin B

Two mitotic Cyclins, A and B, exist in higher eukaryotes, but their specialised functions in mitosis are poorly understood. Using degron tags we analyse how acute depletion of these proteins affects mitosis. Loss of Cyclin A in G2-phase prevents the initial activation of Cdk1. Cells lacking Cyclin B can enter mitosis and phosphorylate most mitotic proteins, because of parallel PP2A:B55 phos-phatase inactivation by Greatwall kinase. The final barrier to mitotic establishment corresponds to nuclear envelope breakdown that requires a decisive shift in the balance of Cdk1 and PP2A:B55 activity. Beyond this point Cyclin B/Cdk1 is essential to phosphorylate a distinct subset mitotic Cdk1 substrates that are essential to complete cell division. Our results identify how Cyclin A, B and Greatwall coordinate mitotic progression by increasing levels of Cdk1-dependent substrate phos-phorylation.

cell biology↗

bioRxiv2018

Antigen receptor control of methionine metabolism in T cells

Immune activated T lymphocytes modulate the activity of key metabolic pathways to support the transcriptional reprograming and reshaping of cell proteomes that permits effector T cell differentiation. The present study uses high resolution mass spectrometry and metabolic labelling to explore how T cells control the methionine cycle to produce methyl donors for protein and nucleotide methylations. We show that antigen receptor engagement controls flux through the methionine cycle and also controls RNA and histone methylations. We establish that the main rate limiting step for the methionine cycle is control of methionine transporter expression by antigen receptors. Only T cells that respond to antigen to upregulate and sustain methionine transport are supplied with the methyl donors that permit the dynamic nucleotide methylations and epigenetic reprogramming that drives T cell differentiation.

immunology↗