Biology subjects

Sailer, C.

Publications and source records attributed to Sailer, C..

9 recordsLinked to original sources

bioRxiv2026

Beta-Adrenergic Stimulation and MYH7 G256E Mutant Gene Dosage Drive Hypertrophic Cardiomyopathy Phenotype Penetrance

AimsHypertrophic cardiomyopathy (HCM) is the most prevalent genetic heart disorder, characterized by significant phenotypic variability even among individuals with identical MYH7 mutations. This study aims to elucidate factors contributing to this variability and identify drivers of phenotype penetrance. We compared the baseline phenotypes of a highly penetrant MYH7 H251N mutation and the variably penetrant MYH7 G256E mutation and investigated the impact of adding beta-adrenergic stimulation and homozygosity on disease phenotype penetrance using cardiomyocytes from an isogenic line of human induced pluripotent stem cells (hiPSC-CMs). Methods and ResultsIsogenic hiPSCs with MYH7 H251N and MYH7 G256E mutations were generated using CRISPR/Cas9 technology and differentiated into cardiomyocytes (CMs). Single-cell RNA sequencing (scRNAseq) and functional analysis of contractile function revealed consistent HCM phenotype presentation in H251N CMs, whereas G256E CMs exhibited a subtle and more variable phenotype. Beta-adrenergic stimulation induced a distinct metabolic stress response in G256E CMs, characterized by impaired mitochondrial ATP upregulation. Increasing mutant gene dosage from hetero- to homozygosity led to consistent increase in hypertrophic and structural gene expression changes in G256E CMs at RNA and protein levels. These changes were distinct from the changes observed with stress response. Importantly, homozygous G256E CMs exhibited a hypercontractile functional and disorganized structural phenotype. Across multiple experimental conditions, we identified consistent increase in cardiomyocyte specific transcriptomic markers such as NPPB, APOE, PDLIM3 and ANKRD1. ConclusionsOur study highlights the use of a variably penetrant MYH7 mutation to investigate factors that influence HCM phenotype penetrance. Specifically, we found that mutant gene dosage and beta-adrenergic stimulation induce distinct HCM disease phenotypes, providing novel insights into mechanisms that may contribute to variable disease expression in HCM. Translational PerspectiveHCM is characterized by significant phenotypic variability, complicating both diagnosis and clinical management. This study explores the factors driving HCM phenotype penetrance using isogenic hiPSC-CMs with MYH7 mutations. We demonstrate that beta-adrenergic stimulation and increased mutant gene dosage significantly impact HCM disease penetrance. Beta-adrenergic stimulation triggers metabolic stress responses, while increased gene dosage leads to a hypercontractile and structurally disorganized phenotype. These findings provide insight into how specific modifiers can shape disease-associated phenotypes in HCM model systems. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/729411v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@16a72d7org.highwire.dtl.DTLVardef@1999ca6org.highwire.dtl.DTLVardef@1fb8752org.highwire.dtl.DTLVardef@7148b2_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2025

The Th1/Th17 axis regulates chimeric antigen receptor (CAR) T cell therapy toxicities

CAR-T therapy has led to significant improvements in patient survival. However, a subset of patients experience high-grade toxicities, including cytokine release syndrome (CRS) and immune cell-associated hematologic toxicity (ICAHT). We utilized IL-2R knockout mice to model cytokine toxicities with elevated levels of IL6, IFN{gamma}, and TNF and increased M1-like macrophages. Onset of CRS was accompanied by a reduction in peripheral blood neutrophils due to disruption of bone marrow neutrophil homeostasis characterized by an increase in apoptotic neutrophils and a decrease in proliferative and mature neutrophils. Both non-tumor-bearing and E-ALL tumor-bearing mice recapitulated the co-occurrence of CRS and neutropenia. IFN{gamma}-blockade alleviated CRS and neutropenia without affecting CAR-T efficacy. Mechanistically, a Th1-Th17 imbalance was observed to drive co-occurrence of CRS and neutropenia in an IFN{gamma}-dependent manner leading to decreased IL-17A and G-CSF, neutrophil production, and neutrophil survival. In patients, we observed an increase in the IFN{gamma}-to-IL-17A ratio in the peripheral blood during high-grade CRS and neutropenia. We have uncovered a biological basis for ICAHT and provide support for the use of IFN{gamma}-blockade to reduce CRS and neutropenia. Statement of SignificanceDespite clinical success of CAR-T therapy, patients develop toxicities such as cytokine release syndrome and neutropenia, whose co-occurrence impacts their survival and quality-of-life. We recapitulate these toxicities in mice to discover their co-occurrence is driven by Th1-Th17 imbalance following CAR-T administration, which can be prevented via IFN{gamma} blockade.

cancer biology↗

bioRxiv2022

Sequence-directed RNA remodeling within a topologically complex RNP substrate

DEAD-box ATPases are ubiquitous enzymes essential in all aspects of RNA biology. However, the limited in vitro catalytic activities described for these enzymes is at odds with their complex cellular roles, most notably in driving large-scale RNA remodeling steps during the assembly of ribonucleoproteins (RNPs). We describe cryo-EM structures of 60S ribosomal biogenesis intermediates that reveal how context-specific RNA unwinding by the DEAD-box ATPase Spb4 results in extensive, sequence-directed remodeling of rRNA secondary structure. Multiple cis and trans interactions stabilize a post-catalytic, high-energy intermediate that drives the organization of the root helix structure within rRNA domain IV. This mechanism explains how limited strand separation by DEAD-box ATPases is leveraged to provide non-equilibrium directionality and ensure efficient and accurate RNP assembly.

biophysics↗

bioRxiv2022

A mono- and intralink filter (mi-filter) to improve false-discovery rates in cross-linking mass spectrometry data

Cross-Linking Mass Spectrometry (XL-MS) has become an indispensable tool for the emerging field of systems structural biology over the recent years. However, the confidence in individual protein-protein interactions (PPIs) depends on the correct assessment of individual inter protein cross-links. This can be challenging, in particularly in samples where relatively few PPIs are detected, as is often the case in complex samples containing low abundant proteins or in in-vivo settings. In this manuscript we are describing a novel mono- and intralink filter (mi-filter) that is applicable to any kind of crosslinking data and workflow. It stipulates that only proteins for which at least one monolink or intra-protein crosslink has been identified within a given dataset are considered for an inter-protein cross-link and therefore participate in a PPI. We show that this simple and intuitive filter has a dramatic effect on different types of crosslinking-data ranging from single protein complexes, over medium-complexity affinity enrichments to proteome-wide cell lysates and significantly lowers the number of false-positive identifications resulting in improved false-discovery rates for inter-protein links in all these types of XL-MS data.

biochemistry↗

bioRxiv2021

A comprehensive landscape of 60S ribosome biogenesis factors

Eukaryotic ribosome biogenesis is facilitated and regulated by numerous ribosome biogenesis factors (RBFs). High-resolution cryo-EM maps have defined the molecular interactions of RBFs during maturation, but many transient and dynamic interactions, particularly during early assembly, remain uncharacterized. Using quantitative proteomics and crosslinking coupled to mass spectrometry (XL-MS) data from a extensive set of pre-ribosomal particles, we derived a comprehensive and time-resolved interaction map of RBF engagement during 60S maturation. A novel filter that efficiently eliminates false positive interactions and integration of our MS data with known structural information allowed us to localize 22 unmapped RBFs to specific biogenesis intermediates and to identify 9 proteins that represent potentially new RBFs. Our analysis reveals an extensive interaction network for the casein kinase complex in 60S maturation and elucidates the timing and molecular function of 60S engagement by DEAD-box ATPases. Our data provide a powerful resource for future studies of 60S ribosome biogenesis.

biochemistry↗

bioRxiv2021

Apomixis and genetic background affect distinct traits in Hieracium pilosella L. grown under competition

BackgroundApomixis, the asexual reproduction through seeds, occurs in over 40 plant families and avoids the hidden cost of sex. Apomictic plants are thought to have an advantage in sparse populations and when colonizing new areas but may have a disadvantage in changing environments because they propagate via fixed genotypes. In this study, we separated the influences of different genetic backgrounds (potentially reflecting local adaptation) from those of the mode of reproduction, i.e., sexual vs. apomictic, on nine fitness-related traits in Hieracium pilosella L. We aimed to test whether apomixis per se may provide a fitness advantage in different competition environments in a common garden setting. ResultsTo separate the effects of genetic background from those of reproductive mode, we generated five families of apomictic and sexual full siblings by crossing two paternal with four maternal parents. Under competition, apomictic plants showed reproductive assurance (probability of seeding, fertility), while offspring of sexual plants with the same genetic background had a higher germination rate. Sexual plants grew better (biomass) than apomictic plants in the presence of grass as a competitor but apomictic plants spread further vegetatively (maximum stolon length) when their competitors were sexual plants of the same species. Furthermore, genetic background as represented by the five full-sibling families influenced maximum stolon length, the number of seeds, and total fitness. Under competition with grass, genetic background influenced fecundity, the number of seeds, and germination rate. ConclusionsOur results suggest that both the mode of reproduction as well as the genetic background affect the success of H. pilosella in competitive environments. Total fitness, the most relevant trait for adaptation, was only affected by the genetic background. However, we also show for the first time that apomixis per se has effects on fitness-related traits that are not confounded by -- and thus independent of -- the genetic background.

plant biology↗

bioRxiv2019

Dynamics of apomictic and sexual reproduction during primary succession on a glacier forefield in the Swiss Alps

Apomixis, the asexual reproduction through seeds, is thought to provide reproductive assurance when ploidy is not even and/or when population density is low. Therefore, apomicts are expected to be more abundant, and the frequency of apomictic offspring higher, at early stages of primary succession when mates are rare.\n\nTo test this hypothesis, we sampled facultative apomictic Hieracium pilosella L. along the successional gradient on a glacier forefield and determined their ploidy, the level of apomixis in their offspring, and the genetic diversity of the entire meta-population and within subpopulations.\n\nWe found that apomixis is more common in odd- and aneuploid cytotypes, which are more frequent at early stages of primary succession. However, apomixis was uncommon at all successional stages and sexual hexaploids were dominating throughout. Reproductive assurance was reflected in the higher fertility of all odd-ploid apomictic plants (3x, 5x) by avoiding meiosis, illustrating that apomixis provides an escape from sterility, as proposed by Darlington. Odd-ploid plants are supposedly better colonizers (Bakers law), which is supported by their higher occurrence close to the glacier snout. Independent of succession, we found gene flow between apomicts and sexuals, which allows for the continuous creation of new apomictic and sexual genotypes.\n\nWe conclude that apomixis in H. pilosella does indeed provide an escape from sterility, and therefore reproductive assurance, in aneuploid cytotypes. We further propose that apomixis preserves beneficial combinations of unlinked alleles in every generation for as long as apomictic genotypes persist in the population.

plant biology↗

bioRxiv2018

Convergent evolution in Arabidopsis halleri and Arabidopsis arenosa on calamine metalliferous soils

It is a plausible hypothesis that parallel adaptation events to the same environmental challenge should result in genetic changes of similar or identical effects, depending on the underlying fitness landscapes. However, systematic testing of this is scarce. Here we examine this hypothesis in two closely related plant species, Arabidopsis halleri and Arabidopsis arenosa, which co-occur at two calamine metalliferous sites harbouring toxic levels of the heavy metals zinc and cadmium. We conduct individual genome resequencing alongside soil elemental analysis for 64 plants from 8 populations on metalliferous and non-metalliferous soils, and identify genomic footprints of selection and local adaptation. Selective sweep and environmental association analyses indicate a modest degree of gene as well as functional network convergence, whereby the proximal molecular factors mediating this convergence mostly differ between site pairs and species. Notably, we observe repeated selection on identical SNPs in several A. halleri genes at two independently colonized metalliferous sites. Our data suggest that species-specific metal handling and other biological features could explain a low degree of convergence between species. The parallel establishment of plant populations on calamine metalliferous soils involves convergent evolution, which will likely be more pervasive across sites purposely chosen for maximal similarity in soil composition.

evolutionary biology↗

bioRxiv2018

Pervasive population genomic consequences of genome duplication in Arabidopsis arenosa

Ploidy-variable species allow direct inference of the effects of chromosome copy number on fundamental evolutionary processes. While an abundance of theoretical work suggests polyploidy should leave distinct population genomic signatures, empirical data remains sparse. We sequenced [~]300 individuals from 39 populations of Arabidopsis arenosa, a naturally diploid-autotetraploid species. We find the impacts of polyploidy on population genomic processes are subtle yet pervasive, including reduced efficiency on linked and purifying selection as well as rampant gene flow from diploids. Initial masking of deleterious mutations, faster rates of nucleotide substitution, and interploidy introgression all conspire to shape the evolutionary potential of polyploids.

evolutionary biology↗