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Early atrial remodeling drives arrhythmia in Fabry disease.
No full textBACKGROUND: Fabry disease (FD) is an X-linked lysosomal storage disorder caused by α-Gal A (α-galactosidase A) deficiency, resulting in multiorgan accumulation of sphingolipid, namely globotriaosylceramide. This triggers ventricular myocardial hypertrophy, fibrosis, and inflammation, driving arrhythmia and sudden death. Atrial fibrillation is common, yet the cellular mechanisms accounting for this are unknown. METHODS: To address this, we conducted ECG analysis from a large cohort of 115 adults with FD at varying cardiomyopathy stages. ECG P-wave characteristics were compared with non-FD controls. Cellular contractile and electrophysiological function were examined in a novel atrial cellular FD model developed and imputed into in silico atrial models to provide insight into mechanisms of arrhythmia. Induced pluripotent stem cells were genome-edited using Clustered Regularly Interspaced Short Palindromic Repeats-Cas9 to introduce the GLA p.N215S variant and differentiated into induced pluripotent stem cell-derived atrial cardiomyocytes (iPSC-CMs). Contraction, calcium handling, and electrophysiology experiments were conducted. Bi-atrial in silico models were developed with cellular changes as in GLA p.N215S iPSC-CMs. RESULTS: ECG analysis demonstrated P-wave duration and PQ interval shortening in FD adults before the onset of cardiomyopathy. Patients with FD exhibited a higher incidence of premature atrial contractions and increased risk of atrial fibrillation compared with healthy controls. GLA p.N215S iPSC-CMs were deficient in α-Gal A and exhibited globotriaosylceramide accumulation. Atrial GLA p.N215S iPSC-CMs demonstrated a more positive diastolic membrane potential, faster action potential upstroke velocity, greater incidence of delayed afterdepolarizations, greater contraction force, and alterations in calcium handling compared with wild-type iPSC-CMs. Simulations with these changes in the in silico models resulted in similar P-wave morphology changes to those seen in early FD cardiomyopathy and increased atrial fibrillation vulnerability. CONCLUSIONS: These findings provide novel insights into underpinning mechanisms for atrial arrhythmia and a rationale for early P-wave changes in FD. These may be targeted to develop therapeutic strategies to reduce the arrhythmic burden in FD
Timed chromatin invasion during mitosis governs prototype foamy virus integration site selection and infectivity.
No full textSelection of a suitable chromatin environment during retroviral integration is a tightly regulated process. Most retroviruses, including spumaretroviruses, require mitosis for nuclear entry. However, whether intrinsic chromatin dynamics during mitosis modulates retroviral genome invasion is unknown. Previous work uncovered critical interactions of prototype foamy virus (PFV) Gag with nucleosomes via a highly conserved arginine anchor residue. Yet, the regulation of Gag-chromatin interaction and its functional consequences for spumaretrovirus biology remain obscure. Here, we investigated the kinetics of chromatin binding by Gag during mitosis and proviral integration in synchronized cells. We showed that alteration of Gag affinity for nucleosome binding induced untimely chromatin tethering during mitosis, decreased infectivity, and redistributed viral integration sites to markers associated with late replication timing of chromosomes. Mutant Gag proteins were, moreover, defective in their ability to displace the histone H4 tail from the nucleosome acidic patch of highly condensed chromatin. These data indicate that the chromatin landscape during Gag-nucleosome interactions is important for PFV integration site selection and that spumaretroviruses evolved high-affinity chromatin binding to overcome early mitosis chromatin condensation
ImmuneLENS characterizes systemic immune dysregulation in aging and cancer.
No full textRecognition and elimination of pathogens and cancer cells depend on the adaptive immune system. Thus, accurate quantification of immune subsets is vital for precision medicine. We present immune lymphocyte estimation from nucleotide sequencing (ImmuneLENS), which estimates T cell and B cell fractions, class switching and clonotype diversity from whole-genome sequencing data at depths as low as 5× coverage. By applying ImmuneLENS to the 100,000 Genomes Project, we identify genes enriched with somatic mutations in T cell-rich tumors, significant sex-based differences in circulating T cell fraction and demonstrated that the circulating T cell fraction in patients with cancer is significantly lower than in healthy individuals. Low circulating B cell fraction was linked to increased cancer incidence. Finally, circulating T cell abundance was more prognostic of 5-year cancer survival than infiltrating T cells.</p
Embracing complexity: Peptides as tuneable scaffolds in the construction of discrete supramolecular systems.
No full textSupramolecular chemistry has advanced rapidly, with scientists using fundamental understanding to generate function from simple building blocks. However, synthetic systems are still in their infancy when compared to biology. The increasing use of peptides in supramolecular structures provides a clear roadmap to more complex function; introducing chiral, information-rich, building blocks from a readily available pool. Peptides have historically been incorporated as modular additions to discrete supramolecular architectures, to interface with biological systems. More recently, supramolecular chemists have embraced the complexity of secondary and tertiary structures, and peptides' intrinsic propensity for folding, to enable the formation of supramolecular architectures built from peptides, leveraging their innate properties. We explore the urgent need to embrace complex, chiral, folded building blocks in discrete supramolecular architectures, and illustrate how this will provide opportunities for novel functions and applications
PolSpec: Polarisation-based detection for versatile, cost-effective rapid hyperspectral imaging.
No full text"PolSpec" is a flexible, cost-effective approach for rapid (including single-shot) spectrally resolved imaging. While established approaches, e.g., using cascades of dichroic beamsplitters, diffractive image splitters, or mosaic filters, typically have pre-determined spectral detection bands with cost and experimental complexity scaling with the number of spectral channels, PolSpec uses polarisation optics to provide continuously varying transmission across a configurable spectral range to generate "spectral modulation vectors" that can represent specific spectral signatures with lower data volumes than full spectral profiles. It can be implemented with almost any detector. Here we demonstrate low-cost single-shot widefield PolSpec-based hyperspectral imaging using a polarisation-resolving camera.</p
Phosphatase specificity influences phosphorylation timing of CDK substrates during the cell cycle.
No full textCell cycle events are ordered by cyclin-dependent kinases (CDKs), which phosphorylate hundreds of substrates. Multiple phosphatases oppose these CDK substrates, yet their collective role in regulating phosphorylation timing in vivo remains unclear. Here, we show that four phosphatases (PP2A-B55, PP2A-B56, CDC14, and PP1) each target distinct subsets of CDK substrate sites in vivo in fission yeast, influencing when phosphorylation occurs during G2 and mitosis. On average, sites dephosphorylated by CDC14 and PP2A-B56 are phosphorylated earlier during G2, followed by sites dephosphorylated by PP1 and PP2A-B55. This suggests that these phosphatases set different phosphorylation thresholds at the G2/M transition. Consistent with this, depleting PP2A-B55 or CDC14 accelerates mitotic onset, likely by advancing phosphorylation of their respective CDK substrates, suggesting these phosphorylation thresholds are important for regulating mitotic onset. Our findings establish in vivo phosphatase substrate specificity as a key factor regulating the timing of CDK substrate phosphorylation throughout the cell cycle
Aspirin prevents metastasis by limiting platelet TXA2 suppression of T cell immunity.
No full textMetastasis is the spread of cancer cells from primary tumours to distant organs and is the cause of 90% of cancer deaths globally1,2. Metastasizing cancer cells are uniquely vulnerable to immune attack, as they are initially deprived of the immunosuppressive microenvironment found within established tumours3. There is interest in therapeutically exploiting this immune vulnerability to prevent recurrence in patients with early cancer at risk of metastasis. Here we show that inhibitors of cyclooxygenase 1 (COX-1), including aspirin, enhance immunity to cancer metastasis by releasing T cells from suppression by platelet-derived thromboxane A2 (TXA2). TXA2 acts on T cells to trigger an immunosuppressive pathway that is dependent on the guanine exchange factor ARHGEF1, suppressing T cell receptor-driven kinase signalling, proliferation and effector functions. T cell-specific conditional deletion of Arhgef1 in mice increases T cell activation at the metastatic site, provoking immune-mediated rejection of lung and liver metastases. Consequently, restricting the availability of TXA2 using aspirin, selective COX-1 inhibitors or platelet-specific deletion of COX-1 reduces the rate of metastasis in a manner that is dependent on T cell-intrinsic expression of ARHGEF1 and signalling by TXA2 in vivo. These findings reveal a novel immunosuppressive pathway that limits T cell immunity to cancer metastasis, providing mechanistic insights into the anti-metastatic activity of aspirin and paving the way for more effective anti-metastatic immunotherapies.</p
Intracellular accumulation of amyloid-ß is a marker of selective neuronal vulnerability in Alzheimer's disease.
No full textDefining how amyloid-β and pTau together lead to neurodegeneration is fundamental to understanding Alzheimer's disease (AD). We used imaging mass cytometry to identify neocortical neuronal subtypes lost with AD in post-mortem brain middle temporal gyri from non-diseased and AD donors. Here we showed that L5,6 RORB+FOXP2+ and L3,5,6 GAD1+FOXP2+ neurons, which accumulate amyloid-β intracellularly from early Braak stages, are selectively vulnerable to degeneration in AD, while L3 RORB+GPC5+ neurons, which accumulate pTau but not amyloid-β, are not lost even at late Braak stages. We discovered spatial associations between activated microglia and these vulnerable neurons and found that vulnerable RORB+FOXP2+ neuronal transcriptomes are enriched selectively for pathways involved in inflammation and glycosylation and, with progression to AD, also protein degradation. Our results suggest that the accumulation of intraneuronal amyloid-β, which is associated with glial inflammatory pathology, may contribute to the initiation of degeneration of these vulnerable neurons
Nanoneedles enable spatiotemporal lipidomics of living tissues.
No full textSpatial biology provides high-content diagnostic information by mapping the molecular composition of tissues. However, traditional spatial biology approaches typically require non-living samples, limiting temporal analysis. Here, to address this limitation, we present a workflow using porous silicon nanoneedles to repeatedly collect biomolecules from live brain tissues and map lipid distribution through desorption electrospray ionization mass spectrometry imaging. This method preserves the integrity of the original tissue while replicating its spatial molecular profile on the nanoneedle substrate, accurately reflecting lipid distribution and tissue morphology. Machine learning analysis of 23 human glioma biopsies demonstrated that nanoneedle sampling enables the precise classification of disease states. Furthermore, a spatiotemporal analysis of mouse gliomas treated with temozolomide revealed time- and treatment-dependent variations in lipid composition. Our approach enables non-destructive spatiotemporal lipidomics, advancing molecular diagnostics for precision medicine