Biology subjects

Roessler, F.

Publications and source records attributed to Roessler, F..

3 recordsLinked to original sources

bioRxiv2024

New evidence for the presence and function of phosphoinositides (PPIs) in the chloroplast

Essential proteins such as the chloroplast-localized Sec14-like protein (CPSFL1) and the vesicle-inducing protein in plastids (VIPP1) have a high affinity for binding phosphoinositides (PPIs) in vitro. PPIs are a specific class of phospholipids characterized by a phosphorylated inositol head group, and while they make up a small fraction of total phospholipids, they are crucial for various regulatory functions. However, the precise subcellular localization of most PPI species in plants remains unclear due to their rapid turnover and low abundance Currently there is no documented evidence for the presence and function of phosphoinositides (PPIs) in chloroplasts. In our study, we developed genetically encoded biosensors targeted to plastids, allowing for the detection of several PPI isoforms, including PI3P, PI4P, PI5P, PI(4,5)P2, and PI(3,5)P2 within chloroplasts. We demonstrated the specificity of these biosensors through immunological methods and observed changes in their distribution patterns when co-expressed with PPI-modifying enzymes (cTP-SAC7, cTP-PTEN, and cTP-dOCRL). Our findings also revealed the association and potential interaction between PI3P and VIPP1. Importantly, we found that elevated PPI levels during stress conditions led to altered biosensor localization, and plants expressing PPI modifiers showed increased sensitivity to drought stress, highlighting the role of PPIs in plant stress responses.

plant biology↗

bioRxiv2023

Noradrenaline release from the locus coeruleus shapes stress-induced hippocampal gene expression

Exposure to an acute stressor triggers a complex cascade of neurochemical events in the brain. However, deciphering their individual impact on stress-induced molecular changes remains a major challenge. Here we combine RNA-sequencing with selective pharmacological, chemogenetic and optogenetic manipulations to isolate the contribution of the locus coeruleus - noradrenaline (LC-NA) system to the acute stress response. We reveal that NA-release during stress exposure regulates a large and reproducible set of genes in the dorsal and ventral hippocampus via {beta}-adrenergic receptors. For a smaller subset of these genes, we show that NA release triggered by LC stimulation is sufficient to mimic the stress-induced transcriptional response. We observe these effects in both sexes, and independent of the pattern and frequency of LC activation. Using a retrograde optogenetic approach, we demonstrate that hippocampus-projecting LC neurons directly regulate hippocampal gene expression. Overall, a highly selective set of astrocyte-enriched genes emerges as key targets of LC-NA activation, most prominently several subunits of protein phosphatase 1 (Ppp1r3c, Ppp1r3d, Ppp1r3g) and type II iodothyronine deiodinase (Dio2). These results highlight the importance of astrocytic energy metabolism and thyroid hormone signaling in LC-mediated hippocampal function and offer new molecular targets for understanding how NA impacts brain function in health and disease.

neuroscience↗

bioRxiv2022

Alternative splicing analysis benchmark with DICAST

Alternative splicing is a major contributor to transcriptome and proteome diversity in health and disease. A plethora of tools have been developed for studying alternative splicing in RNA-seq data. Previous benchmarks focused on isoform quantification and mapping. They neglected event detection tools, which arguably provide the most detailed insights into the alternative splicing process. DICAST offers a modular and extensible framework for the analysis of alternative splicing integrating 11 splice-aware mapping and eight event detection tools. We benchmark all tools extensively on simulated as well as whole blood RNA-seq data. STAR and HISAT2 demonstrated the best balance between performance and run time. The performance of event detection tools varies widely with no tool outperforming all others. DICAST allows researchers to employ a consensus approach to consider the most successful tools jointly for robust event detection. Furthermore, we propose the first reporting standard to unify existing formats and to guide future tool development.

bioinformatics↗