Biology subjects

Sauer, C.

Publications and source records attributed to Sauer, C..

6 recordsLinked to original sources

bioRxiv2026

HvbZIP33 and HvbZIP76 have overlapping roles in foliar transpiration in drought-stressed barley

Basic leucine zippers (bZIP) constitute one of the biggest protein families and evolutionarily conserved transcription factors (TFs) in plants. We obtained mutant lines for two bZIP TFs, HvbZIP33 and HvbZIP76, in the genetic background of the barley cultivar Golden Promise (GP) via targeted gene-specific mutagenesis using an RNA-guided Cas9 endonuclease. A comprehensive morphological, physiological and transcriptomic analysis was performed in wild-type GP compared with hvbzip33 and hvbzip76 mutants under drought stress. The morphological and physiological changes were similar in both mutants and in the wild-type GP. Most strikingly, the mutants exhibited accelerated wilting and increased water loss. This effect was primarily caused by higher stomatal conductance (gs) and transpiration rate (E) in mutants compared to wild-type GP under both control and drought conditions, which in turn had a detrimental effect on the mutants intrinsic water use efficiency (iWUE). Likewise, the transcriptome profiles of hvbzip33 and hvbzip76 were more similar to each other than those of wild-type GP. We found that the number of differentially regulated genes under control versus drought-stress conditions was higher in the mutants than in wild-type GP, suggesting that the mutants try to compensate for accelerated foliar water loss. The study highlights the essential roles of HvbZIP33 and HvbZIP76 in balancing water loss in barley. These findings provide a foundation for engineering enhanced drought tolerance in barley through targeted manipulation of these genes to optimize transpiration rates.

genetics↗

bioRxiv2025

A genome-wide survey reveals a diverse array of enhancers coordinate the Drosophila innate immune response

To defend against microbes, animals regulate a complex immune response. The Drosophila innate immune system deploys a large transcriptional induction of signaling proteins, anti-microbial effectors, and other critical immune factors. This transcriptional response is encoded in enhancers, cis-regulatory sequences that modulate gene expression by binding transcription factors (TFs). While enhancers and transcription factor binding sites (TFBS) have been identified for several immune responsive genes in Drosophila, most enhancers that regulate immune-induced genes are unknown. By identifying enhancers, we can understand how their composition controls expression and contributes to infection outcome. We employed STARR-seq (Self Transcribing Active Regulatory-Region sequencing) in a hemocyte-like cell line to identify immune-specific enhancers across the D. melanogaster genome and performed ATAC-seq in hemocytes extracted from adult flies to assess the chromatin state of these enhancers before and after immune stimulus. We identified thousands of enhancers responsive to IMD stimulation, one of the two primary immune signaling pathways in Drosophila. As expected, immune enhancers are enriched for motifs of Relish, an NF-{kappa}B factor, and Kay/Jra, a bZip heterodimer pair, involved in the Imd and JNK pathways respectively, compared to enhancers active in unstimulated cells. However, when grouping enhancers by their target genes expression timing or functional role or by the enhancers chromatin accessibility pre- or post-stimulus, different groups of TFBS motifs are enriched, suggesting distinct regulatory logic for different parts of the immune response. Identification and characterization of the diverse array of enhancers that regulate the innate immune response expands our understanding of how animals fight infections.

genomics↗

bioRxiv2024

Siderophore piracy enables the nasal commensal Staphylococcus lugdunensis to antagonize the pathogen Staphylococcus aureus

Bacterial pathogens such as Staphylococcus aureus colonize body surfaces of part of the human population, which represents a critical risk factor for skin disorders and invasive infections. However, such pathogens do not belong to the human core microbiomes - beneficial commensal bacteria can often prevent the persistence of certain pathogens - using molecular strategies that are only superficially understood. We recently reported that the commensal bacterium Staphylococcus lugdunensis produces the novel antibiotic lugdunin, which eradicates S. aureus from nasal microbiomes of hospitalized patients. However, it has remained unclear if S. lugdunensis may affect S. aureus carriage in the general population and how S. lugdunensis carriage could be promoted to enhance its S. aureus-eliminating capacity. We could cultivate S. lugdunensis from the noses of 6.3% of healthy human volunteers. In addition, S. lugdunensis DNA could be identified in metagenomes of many culture-negative nasal samples indicating that cultivation success depends on a specific bacterial threshold density. Healthy S. lugdunensis carriers had a 5.2-fold lower propensity to be colonized by S. aureus indicating that lugdunin can eliminate S. aureus also in healthy humans. S. lugdunensis-positive microbiomes were dominated by either Staphylococcus epidermidis, Corynebacterium species, or Dolosigranulum pigrum. These and further bacterial commensals, whose abundance was positively associated with S. lugdunensis, promoted S. lugdunensis growth in co-culture. Such mutualistic interactions depended on the production of iron-scavenging siderophores by supporting commensals, and on the capacity of S. lugdunensis to import siderophores. These findings underscore the importance of microbiome homeostasis for eliminating pathogen colonization. Elucidating mechanisms that drive microbiome interactions will become crucial for microbiome-precision editing approaches.

microbiology↗

bioRxiv2023

Predicting response to cytotoxic chemotherapy

Cytotoxic chemotherapies have been a crucial part of cancer treatment for over 40 years. While their primary target is cancer cells, they can also harm normal cells, resulting in dose-limiting toxicity. Most chemotherapies were approved before the advent of precision biomarkers, as such, many patients experience severe toxic side effects without any benefit. To address this challenge, we have developed three precision biomarkers to predict response to platins, taxanes, and anthracyclines. Based on chromosomal instability (CIN) signatures, these biomarkers can be computed from a single genomic test. For platins and taxanes, we used CIN signatures related to impaired homologous recombination, while for anthracyclines, we discovered a CIN signature representing micronuclei induction which predicts resistance. In a clinical study involving 41 high-grade serous ovarian cancers, patients predicted to be sensitive by these biomarkers showed significantly prolonged progression-free survival. To further validate the effectiveness of the taxane and anthracycline predictors, we conducted a retrospective randomised control study involving 182 ovarian and 219 breast cancer patients. Patients predicted as resistant showed increased risk of time to treatment failure compared to standard of care, hazard ratios of 1.73 (95%CI=0.98-3.07) for taxane in ovarian, 3.67 (95%CI=2.12-6.34) for taxane in breast, and 1.93 (95%CI=1.22-3.04) for doxorubicin in ovarian. We also found that liquid biopsies can be used to make these predictions in up to 30% of ovarian cancer patients. Our findings highlight the clinical value of CIN signatures in predicting treatment response to various chemotherapies across multiple different types of cancer. The ability to quantify multiple CIN signature biomarkers using a single genomic test offers a unified approach to guide treatment decisions for cytotoxic chemotherapies. Ultimately, this has the potential to transform the current one-size-fits-all chemotherapy approach into a more precise and tailored form of medicine.

cancer biology↗

bioRxiv2020

Somatic chromosomal number alterations affecting driver genes inform in-vitro and clinical drug response in high-grade serous ovarian cancer

The genomic complexity and heterogeneity of high-grade serous ovarian cancer (HGSOC) has hampered the realisation of successful therapies and effective personalised treatment is an unmet clinical need. Here we show that primary HGSOC spheroid models can be used to predict drug response and use them to demonstrate that somatic copy number alterations (SCNAs) in frequently amplified HGSOC cancer genes significantly correlate with gene expression and drug response. These genes are often located in areas of the genome with frequent clonal SCNAs. MYC chromosomal copy number is associated with ex-vivo and clinical response to paclitaxel and ex-vivo response to mTORC1/2 inhibition. Activation of the mTOR survival pathway in the context to MYC-amplified HGSOC is mostly due to increased prevalence of SCNAs in genes from the PI3K pathway. These results suggest that SCNAs encompassing driver genes could be used to inform therapeutic response in the context of clinical trials testing personalised medicines.

cancer biology↗

bioRxiv2018

FASTGenomics: An analytical ecosystem for single-cell RNA sequencing data

Recent technological advances enable genomics of individual cells, the building blocks of all living organisms. Single cell data characteristics differ from those of bulk data, which led to a plethora of new analytical strategies. However, solutions are only useful for experts and currently, there are no widely accepted gold standards for single cell data analysis. To meet the requirements of analytical flexibility, ease of use and data security, we developed FASTGenomics (https://fastgenomics.org) as a powerful, efficient, versatile, robust, safe and intuitive analytical ecosystem for single-cell transcriptomics.

bioinformatics↗