Biology subjects

Evers, B. M.

Publications and source records attributed to Evers, B. M..

At least 19 recordsLinked to original sources

bioRxiv2026

Reply to: Structural polymorphism of amyloid fibrils in ATTR amyloidosis revealed by cryo-electron microscopy

In the paper by Nguyen et al, published in Nature Communications in 2024, we describe structural polymorphism in fibrils extracted from patients with ATTR amyloidosis. ATTR amyloidosis is characterized by deposition of transthyretin amyloid fibrils across multiple organs, resulting in marked phenotypic variability. Previous studies on ATTR suggest its phenotypic variability may be linked to differences in fibril structure, as demonstrated in amyloid diseases such as AA amyloidosis, tauopathies, or synucleinopathies. Thus far, most ATTR fibrils adopt a strikingly similar fold across patients and affected organs. The most notable exception is described in the study by Nguyen et al., where we report the identification of two co-existing polymorphs in cardiac fibrils from three patients with the ATTRv-I84S variant. These cardiac polymorphs differ in conformation of the segment Gly57 to Gly67, termed the gate, which regulates access to a central polar channel within the fibril core. In one polymorph, the gate adopts an open conformation, exposing the channel, whereas in the other it is closed, shielding it. Whether these polymorphs extend beyond cardiac tissue remains unknown. Here, we address this question by extending our analysis to additional organs from a fourth patient with ATTRv-I84S amyloidosis.

biophysics↗

bioRxiv2026

Transthyretin amyloid fibrils adopt distinct folds in the brain

Amyloid deposition in the central nervous system is increasingly recognized in transthyretin (ATTR) amyloidosis, particularly in patients with prolonged survival following liver transplantation or disease-modifying therapies. However, the structural basis of transthyretin aggregation in the brain remains unknown. Here we determine cryo-electron microscopy (cryo-EM) structures of ex vivo brain-derived ATTR fibrils from patients carrying the ATTRv-V30M and ATTRv-V30G variants. Both fibrils adopt folds distinct from those previously reported in peripheral tissues and the vitreous humor. V30M fibrils exhibit a continuous ordered core spanning residues Pro11-Asn124, whereas V30G fibrils consist of a substantially reduced ordered core, revealing pronounced structural divergence even within the same tissue environment. Despite this diversity, comparative analyses identify conserved regions across ATTR fibrils, including a segment implicated in transthyretin aggregation and targeted for diagnostic and therapeutic development. These results provide direct evidence that local tissue context can shape amyloid fibril architecture in human disease.

biophysics↗

bioRxiv2025

Airflow Determines Natural Airborne Transmission of Tuberculosis in a Guinea Pig Model

Tuberculosis (TB) is transmitted through the air, yet the determinants of natural airborne transmission remain poorly defined. Early twentieth-century guinea pig studies demonstrated efficient airborne transmission of Mycobacterium tuberculosis (Mtb), but this paradigm has not been reestablished in contemporary containment facilities. Here, we show that ventilation can impose airflow constraints that suppress transmission under otherwise permissive conditions. Using a guinea pig model of animal-to-animal exposure, we combined transmission experiments with quantitative airflow measurements and particle transport modeling to explain why some housing configurations fail to support effective exposure. Static environments and excessive unidirectional airflow prevented transmission, whereas controlled low-velocity airflow restored evidence of exposure, including tuberculin skin test conversion, antigen-specific immune responses, and pulmonary inflammation consistent with early infection. These findings identify airflow as a critical constraint on airborne TB transmission and provide a reproducible framework to dissect host, microbial, and environmental determinants of spread.

physiology↗

bioRxiv2025

Structural polymorphism of ex-vivo ALECT2 amyloid fibrils revealed by cryo-EM

ALECT2 amyloidosis is a rare systemic disease characterized by the pathological deposition of leukocyte cell-derived chemotaxin-2 (LECT2) as amyloid fibrils, primarily affecting the kidneys and liver. The molecular mechanisms underlying LECT2 aggregation remain poorly defined, hindering diagnostic and therapeutic development. Here, we present cryo-electron microscopy structures of ex-vivo ALECT2 fibrils extracted from a patients kidney. We identified three fibril polymorphs: a predominant single-protofilament morphology and two minor double-protofilament morphologies. The dominant single-protofilament morphology comprises the full-length 133-residue LECT2 protein and retains all three native disulfide bonds. Low-resolution reconstructions of double-protofilament morphologies suggest they adopt a similar fold to the single protofilament morphology, but form paired assemblies with different inter-filament interfaces. Mass spectrometry also reveals acetylation within the fibrils. These findings offer critical insights into the structural basis of ALECT2 amyloid formation and identify molecular features that could inform future diagnostic and therapeutic approaches.

biophysics↗

bioRxiv2025

Structural variability of apolipoprotein A-I amyloid fibrils across organs, mutations, and clinical presentations, revealed by cryo-EM

Hereditary apolipoprotein A-I (AapoA-I) amyloidosis is a rare systemic disease caused by the deposition of amyloid fibrils formed by apolipoprotein A-I in multiple organs, leading to severe clinical outcomes. With no available therapies or diagnostic tools, defining the structure of AApoA-I fibrils is crucial to understanding disease mechanisms and guiding intervention. Using cryo-electron microscopy, we analyzed AApoA-I fibrils from the heart, kidney, liver, and spleen of patients carrying G26R, L90P, and R173P mutations. G26R fibrils, regardless of organ, exhibited untwisted morphologies and could not be resolved structurally. Conversely, L90P and R173P fibrils displayed a compact diabolo-shaped conformation in all organs analyzed. Their high-resolution maps enabled visualization of cis-Proline 66, which may represent a potential conformational switch during fibril formation. Our findings suggest that mutation-driven polymorphism may influence organ tropism and clinical presentation. This work advances our understanding of AapoA-I fibril assembly and provides insights toward developing targeted clinical tools.

biophysics↗

bioRxiv2025

Plagl1 and Lrrc58 control mammalian body size by triggering target-directed microRNA degradation of miR-322 and miR-503

Precise control of microRNA (miRNA) expression is critical during development. An important mechanism of miRNA regulation is target-directed microRNA degradation (TDMD), a pathway in which the binding of miRNAs to specialized trigger RNAs induces ubiquitylation and decay of associated Argonaute (AGO) proteins by the ZSWIM8 ubiquitin ligase. Concomitant release of miRNAs results in their rapid turnover. ZSWIM8-deficient mice exhibit reduced body size, cardiopulmonary and neurodevelopmental defects, and perinatal lethality. Despite widespread dysregulation of miRNAs in these animals, the vast majority of presumptive trigger RNAs that induce decay of ZSWIM8-regulated miRNAs remain undefined. Here, using AGO crosslinking and sequencing of hybrids (AGO-CLASH), a high-throughput method for identifying miRNA binding sites, we report the identification of Plagl1 as a TDMD trigger for miR-322-5p, and Lrrc58 and Malat1 as TDMD triggers for miR-503-5p in mouse embryonic fibroblasts (MEFs). In mice, deletion of the miR-322-5p and miR-503-5p trigger sites in the Plagl1 and Lrrc58 3' UTRs, respectively, abrogated TDMD of these miRNAs and resulted in miR-322/503-dependent embryonic growth restriction, recapitulating a key feature of the Zswim8--/-- phenotype. Thus, Plagl1 and Lrrc58 act as triggers for degradation of miR-322-5p and miR-503-5p, revealing a noncoding function for these mRNAs as regulators of mammalian body size.

molecular biology↗

bioRxiv2025

Transmembrane Serine Protease TMPRSS11B promotes an acidified tumor microenvironment and immune suppression in lung squamous cell carcinoma

Lung cancer is the leading cause of cancer-related deaths worldwide. Existing therapeutic options have limited efficacy, particularly for lung squamous cell carcinoma (LUSC), underscoring the critical need for the identification of new therapeutic targets. We previously demonstrated that the Transmembrane Serine Protease TMPRSS11B promotes transformation of human bronchial epithelial cells and enhances lactate export from LUSC cells. To determine the impact of TMPRSS11B activity on the host immune system and the tumor microenvironment (TME), we evaluated the effect of Tmprss11b depletion in a syngeneic mouse model. Tmprss11b depletion significantly reduced tumor burden in immunocompetent mice and triggered an infiltration of immune cells. RNA FISH analysis and spatial transcriptomics in the autochthonous Rosa26-Sox2-Ires-GfpLSL/LSL; Nkx2-1fl/fl; Lkb1fl/fl (SNL) model revealed an enrichment of Tmprss11b expression in LUSC tumors, specifically in Krt13+ hillock-like cells. Ultra-pH sensitive nanoparticle imaging and metabolite analysis identified regions of acidification, elevated lactate, and enrichment of M2-like macrophages in LUSC tumors. These results demonstrate that TMPRSS11B promotes an acidified and immunosuppressive TME and nominate this enzyme as a therapeutic target in LUSC.

cancer biology↗

bioRxiv2024

Coordinated translational control of multiple immune checkpoints by the integrated stress response pathway in lung cancer

The integrated stress response (ISR) is an adaptive pathway hijacked by cancer cells to survive cellular stresses in the tumor microenvironment. ISR activation potently induces Programmed Death Ligand 1 (PD-L1), leading to suppression of anti-tumor immunity. Here we sought to uncover additional immune checkpoint proteins regulated by the ISR to elucidate mechanisms of tumor immune escape. We show that CD155 and PD-L1 are coordinately induced by the ISR, enhancing translation of both immune checkpoint proteins through bypass of inhibitory upstream open reading frames (uORFs) in their 5' UTRs. Analysis of primary human lung tumors identifies a significant correlation between PD-L1 and CD155 expression. ISR activation accelerates tumorigenesis and inhibits T cell function, effects that can be overcome by combining PD-1 blockade with the ISR inhibitor ISRIB. These studies uncover a novel mechanism by which two immune checkpoint proteins are coordinately regulated and suggest a new therapeutic strategy for lung cancer patients. Statement of SignificanceThis study uncovers a novel mechanism for the coordinated translational regulation of the PD- L1/PD1 and CD155/TIGIT immune checkpoint pathways and highlights the ISR as a therapeutic vulnerability for lung cancer. Inhibition of the ISR pathway bolsters PD-1 blockade, potentially unveiling a new therapeutic strategy for lung cancer patients.

cancer biology↗

bioRxiv2024

Dysregulation of FicD AMPylation causes diabetes by disrupting pancreatic endocrine homeostasis

Bi-functional enzyme FicD regulates the endoplasmic reticulum chaperone BiP using AMPylation and deAMPylation during ER homeostasis and stress, respectively. Human FicD with an arginine-to-serine mutation disrupts FicD deAMPylation activity resulting in severe neonatal diabetes. We generated the FicDR371S mutation in mice to create a pre-clinical murine model for neonatal diabetes. We observed elevated BiP AMPylation levels across multiple tissues and signature markers for diabetes including glucose intolerance and reduced serum insulin levels. While the pancreas of FicDR371S mice appeared normal at birth, adult FicDR371S mice displayed disturbed pancreatic islet organization that progressed with age. FicDR371S mice provide a preclinical mouse model for the study of UPR associated diabetes and demonstrate the essentiality of FicD for tissue resilience.

physiology↗

bioRxiv2024

Cancer Cachexia in STK11/LKB1-mutated NSCLC is Dependent on Tumor-secreted GDF15

Cachexia is a wasting syndrome comprised of adipose, muscle, and weight loss observed in cancer patients. Tumor loss-of-function mutations in STK11/LKB1, a regulator of the energy sensor AMP-activated protein kinase, induce cancer cachexia (CC) in preclinical models and are associated with cancer-related weight loss in NSCLC patients. Here we characterized the relevance of the NSCLC-associated cachexia factor growth differentiation factor 15 (GDF15) in several patient-derived and genetically engineered STK11/LKB1-mutant NSCLC cachexia lines. Both tumor mRNA expression and serum concentrations of tumor-derived GDF15 were significantly elevated in multiple mice transplanted with patient-derived STK11/LKB1-mutated NSCLC lines. GDF15 neutralizing antibody administered to mice transplanted with patient- or mouse-derived STK11/LKB1-mutated NSCLC lines suppressed cachexia-associated adipose loss, muscle atrophy, and changes in body weight. The silencing of GDF15 in multiple human NSCLC lines was also sufficient to eliminate in vivo circulating GDF15 levels and abrogate cachexia induction, suggesting that tumor and not host tissues represent a key source of GDF15 production in these cancer models. Finally, reconstitution of wild-type STK11/LKB1 in a human STK11/LKB1 loss-of-function NSCLC line that normally induces cachexia in vivo correlated with the absence of tumor-secreted GDF15 and rescue from the cachexia phenotype. The current data provide evidence for tumor-secreted GDF15 as a conduit and a therapeutic target through which NSCLCs with STK11/LKB1 loss-of-function mutations promote cachexia-associated wasting.

cancer biology↗

bioRxiv2024

Multi-organ structural homogeneity of amyloid fibrils in ATTRv-T60A amyloidosis patients, revealed by Cryo-EM

ATTR amyloidosis is a degenerative disorder characterized by the systemic deposition of the protein transthyretin. These amyloid aggregates of transthyretin (ATTR) can deposit in different parts of the body causing diverse clinical manifestations. Our laboratory aims to investigate a potential relationship between the different genotypes, organ of deposition, clinical phenotypes, and the structure of ATTR fibrils. Using cryo-electron microscopy, we have recently described how the neuropathic related mutations ATTRv-I84S and ATTRv-V122{Delta} can drive structural polymorphism in ex vivo fibrils. Here we question whether the mutation ATTRv-T60A, that commonly triggers cardiac and neuropathic symptoms, has a similar effect. To address this question, we extracted and determined the structure of ATTR-T60A fibrils from multiple organs (heart, thyroid, kidney, and liver) from the same patient and from the heart of two additional patients. We have found a consistent conformation among all the fibril structures, acquiring the "closed-gate morphology" previously found in ATTRwt and others ATTRv related to cardiac or mixed manifestations. The closed-gate morphology is composed by two segments of the protein that interact together forming a polar channel, where the residues glycine 57 to isoleucine 68 act as a gate of the polar cavity. Our study indicates that ATTR-T60A fibrils present in peripheral organs adopt the same structural conformation in all patients, regardless of the organ of deposition.

molecular biology↗

bioRxiv2023

Target-directed microRNA degradation regulates developmental microRNA expression and embryonic growth in mammals

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that play critical roles in development and disease. Target-directed miRNA degradation (TDMD), a pathway in which miRNAs that bind to specialized targets with extensive complementarity are rapidly decayed, has emerged as a potent mechanism of controlling miRNA levels. Nevertheless, the biological role and scope of miRNA regulation by TDMD in mammals remains poorly understood. To address these questions, we generated mice with constitutive or conditional deletion of Zswim8, which encodes an essential TDMD factor. Loss of Zswim8 resulted in developmental defects in heart and lung, growth restriction, and perinatal lethality. Small RNA sequencing of embryonic tissues revealed widespread miRNA regulation by TDMD and greatly expanded the known catalog of miRNAs regulated by this pathway. These experiments also uncovered novel features of TDMD-regulated miRNAs, including their enrichment in co-transcribed clusters and examples in which TDMD underlies arm switching, a phenomenon wherein the dominant strand of a miRNA precursor changes in different tissues or conditions. Importantly, deletion of two miRNAs, miR-322 and miR-503, rescued growth of Zswim8 null embryos, directly implicating the TDMD pathway as a regulator of mammalian body size. These data illuminate the broad landscape and developmental role of TDMD in mammals.

molecular biology↗

bioRxiv2023

Maintenance of pig brain function under extracorporeal pulsatile circulatory control (EPCC)

Selective vascular access to the brain is desirable in metabolic tracer, pharmacological and other studies aimed to characterize neural properties in isolation from somatic influences from chest, abdomen or limbs. However, current methods for artificial control of cerebral circulation can abolish pulsatility-dependent vascular signaling or neural network phenomena such as the electrocorticogram even when preserving individual neuronal activity. Thus, we set out to mechanically render cerebral hemodynamics fully regulable to replicate or modify native pig brain perfusion. To this end, blood flow to the head was surgically separated from the systemic circulation and full extracorporeal pulsatile circulatory control (EPCC) delivered via a modified aorta or brachiocephalic artery. This control relied on a computerized algorithm that maintained, for several hours, blood pressure, flow and pulsatility at near-native values individually measured before EPCC. Continuous electrocorticography and brain depth electrode recordings were used to evaluate brain activity relative to the standard offered by awake human electrocorticography. Under EPCC, this activity remained unaltered or minimally perturbed compared to the native circulation state, as did cerebral oxygenation, pressure, temperature and microscopic structure. Thus, our approach enables the study of neural activity and its circulatory manipulation in independence of most of the rest of the organism.

neuroscience↗

bioRxiv2023

Cancer mutations rewire the RNA methylation specificity of METTL3-METTL14

Chemical modification of RNAs is important for post-transcriptional gene regulation. The METTL3-METTL14 complex generates most N6-methyladenosine (m6A) modifications in mRNAs, and dysregulated methyltransferase expression has been linked to numerous cancers. Here we show that changes in m6A modification location can impact oncogenesis. A gain-of-function missense mutation found in cancer patients, METTL14R298P, promotes malignant cell growth in culture and in transgenic mice. The mutant methyltransferase preferentially modifies noncanonical sites containing a GGAU motif and transforms gene expression without increasing global m6A levels in mRNAs. The altered substrate specificity is intrinsic to METTL3-METTL14, helping us to propose a structural model for how the METTL3-METTL14 complex selects the cognate RNA sequences for modification. Together, our work highlights that sequence-specific m6A deposition is important for proper function of the modification and that noncanonical methylation events can impact aberrant gene expression and oncogenesis.

biochemistry↗

bioRxiv2023

LY6E protects mice from pathogenic effects of murine coronavirus and SARS-CoV-2

LY6E is an antiviral protein that inhibits coronavirus entry. Its expression in immune cells allows mice to control murine coronavirus infection. However, it is not known which immune cell subsets mediate this control or whether LY6E protects mice from SARS-CoV-2. In this study, we used tissue-specific Cre recombinase expression to ablate Ly6e in distinct immune compartments or in all epiblast-derived cells, and bone marrow chimeras to target Ly6e in a subset of radioresistant cells. Mice lacking Ly6e in Lyz2-expressing cells and radioresistant Vav1-expressing cells were more susceptible to lethal murine coronavirus infection. Mice lacking Ly6e globally developed clinical disease when challenged with the Gamma (P.1) variant of SARS-CoV-2. By contrast, wildtype mice and mice lacking type I and type III interferon signaling had no clinical symptoms after SARS-CoV-2 infection. Transcriptomic profiling of lungs from SARS-CoV-2-infected wildtype and Ly6e knockout mice revealed a striking reduction of secretory cell-associated genes in infected knockout mice, including Muc5b, an airway mucin-encoding gene that may protect against SARS-CoV-2-inflicted respiratory disease. Collectively, our study reveals distinct cellular compartments in which Ly6e confers cell intrinsic antiviral effects, thereby conferring resistance to disease caused by murine coronavirus and SARS-CoV-2.

microbiology↗

bioRxiv2022

Fic-mediated AMPylation tempers the Unfolded Protein Response during physiological stress

The proper balance of synthesis, folding, modification and degradation of proteins, also known as protein homeostasis, is vital to cellular health and function. The unfolded protein response (UPR) is activated when the mechanisms maintaining protein homeostasis in the endoplasmic reticulum (ER) become overwhelmed. However, prolonged or strong UPR responses can result in elevated inflammation and cellular damage. Previously, we discovered that the bifunctional enzyme Fic can modulate the UPR response via post-translational modification of BiP by AMPylation and deAMPylation. Loss of fic in Drosophila leads to vision defects and altered UPR activation in the fly eye. To investigate the importance of Fic-mediated AMPylation in a mammalian system, we generated a conditional null allele of Fic in mice and characterized the effect of Fic loss on the exocrine pancreas. Compared to controls, Fic-/- mice exhibit elevated serum markers for pancreatic dysfunction and display enhanced UPR signaling in the exocrine pancreas in response to physiologic and pharmacological stress. In addition, both fic-/- flies and Fic-/- mice show reduced capacity to recover from damage by stress that triggers the UPR. These findings show that Fic- mediated AMPylation acts as a molecular rheostat that is required to temper the UPR response in the mammalian pancreas during physiological stress.

physiology↗

bioRxiv2022

Tau seeding without tauopathy

Neurodegenerative tauopathies such as Alzheimers disease (AD) are caused by brain accumulation of tau assemblies. Evidence suggests tau functions as a prion, and cells and animals efficiently propagate unique tau assemblies. This suggests a dedicated cellular replication machinery, with normal physiologic function for tau seeds. Consequently, we hypothesized that healthy control brains would have seeding activity. We recently developed a novel monoclonal antibody (MD3.1) specific for tau seeds. We used this antibody to immunopurify tau from the parietal and cerebellar cortices of 19 healthy subjects ranging 19-65 years. We detected seeding in the parietal cortex, but not in the cerebellum, or in wild-type or human tau knockin mice, suggesting that cellular/genetic context dictates development of seed-competent tau. Seeding did not correlate with subject age or brain tau levels. Dot blot analyses revealed no AT8 immunoreactivity above background levels in parietal and cerebellar extracts and <1/100 of that present in AD. Based on binding to a panel of antibodies, the conformational characteristics of control seeds differed from AD, suggesting a unique underlying assembly, or structural ensemble. Taus ability to adopt self-replicating conformations under non-pathogenic conditions may reflect normal function that goes awry in disease states.

neuroscience↗

bioRxiv2021

STAG2 promotes the myelination transcriptional program in oligodendrocytes

Cohesin folds chromosomes via DNA loop extrusion. Cohesin-mediated chromosome loops regulate transcription by shaping long-range enhancer-promoter interactions, among other mechanisms. Mutations of cohesin subunits and regulators cause human developmental diseases termed cohesinopathy. Vertebrate cohesin consists of SMC1, SMC3, RAD21, and either STAG1 or STAG2. To probe the physiological functions of cohesin, we created conditional knockout (cKO) mice with Stag2 deleted in the nervous system. Stag2 cKO mice exhibit growth retardation, neurological defects, and premature death, in part due to insufficient myelination of nerve fibers. Stag2 cKO oligodendrocytes exhibit delayed maturation and downregulation of myelination-related genes. Stag2 loss reduces promoter-anchored loops at downregulated genes in oligodendrocytes. Thus, STAG2-cohesin generates promoter-anchored loops at myelination-promoting genes to facilitate their transcription. Our study implicates defective myelination as a contributing factor to cohesinopathy and establishes oligodendrocytes as a relevant cell type to explore the mechanisms by which cohesin regulates transcription.

developmental biology↗