Biology subjects

Diercks, B.-P.

Publications and source records attributed to Diercks, B.-P..

3 recordsLinked to original sources

bioRxiv2026

Ryanodine receptor 1 is dispensable for CD4+ T-cell differentiation and effector function in intestinal inflammation models

T-cell receptor signaling is necessary for the activation and differentiation of CD4 T cells. Calcium (Ca2+) signaling is essential for this process, and the complexity of Ca2+ channels presents a potential therapeutic target for modulating the strength of T-cell receptor signaling and further differentiation of CD4 T cells. Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent Ca2+-mobilizing second messenger that triggers Ca2+ release through ryanodine receptor 1 (RYR1) in T cells. While the molecular and biophysical properties of NAADP-induced Ca2+ microdomains in T cells have been thoroughly investigated, and the function of the NAADP-HN1L/JPT2-RYR1 axis has been proven in T-cell activation and proliferation, its role in intestinal inflammation in vivo remains to be elucidated. In this study, we generated a conditional knockout mouse with Ryr1 deleted in {beta} T cells to investigate the functional relevance of RYR1 signaling in CD4 T cells. Ryr1 deletion in CD4+ T cells decreased TCR-induced Ca2+ microdomain formation, reduced peak Ca2+ amplitude and delayed initial velocity of global Ca2+ signaling in vitro. However, Ryr1 expression in CD4 T cells was dispensable for their pathogenicity in murine models of intestinal inflammation. Thus, Ryr1 expression in CD4+ T cells plays a redundant role in intestinal inflammation.

immunology↗

bioRxiv2025

Immune activation of primary human macrophages is suppressed by the coordinated action of Yersinia effectors

In order to suppress the host immune response, numerous bacterial pathogens utilise a type 3 secretion system (T3SS) that injects effector proteins into host target cells. We investigated the T3SS effectors of Yersinia enterocolitica (Yops) for their individual and combined effects on gene expression, inflammasome formation and calcium signaling in primary human macrophages. YopP efficiently suppressed the up- and down-regulation of thousands of macrophage genes induced by the bacterias inflammatory stimuli. This was accompanied by parallel changes in histone 3-serine 10 phosphorylation, suggesting a higher-level regulatory mechanism. Surprisingly, YopM and YopQ counteracted selected YopP effects on gene expression, e.g., of cytokine pathways. A combination of YopP and YopQ, but not other combinations of Yops or any single Yop, reduced inflammasome formation. YopH alone blocked calcium transients in infected macrophages. We propose that the T3SS effectors of Yersinia antagonistically, synergistically or individually subdue major immune pathways of human macrophages to jointly suppress macrophage activation.

cell biology↗

bioRxiv2021

Time-Dependent Image Restoration of Low-SNR Live Cell Ca2+ Fluorescence Microscopy Data

Live cell Ca2+ fluorescence microscopy is a cornerstone of cellular signaling analysis and imaging. The demand for high spatial and temporal imaging resolution is, however, intrinsically linked to a low signal-to-noise ratio (SNR) of the acquired spatio-temporal image data, which impedes subsequent image analysis. Advanced deconvolution and image restoration algorithms can partly mitigate the corresponding problems, but are usually defined only for static images. Frame-by-frame application to spatio-temporal image data neglects inter-frame contextual relationships and temporal consistency of the imaged biological processes. Here, we propose a variational approach to time-dependent image restoration built on entropy-based regularization specifically suited to process low- and lowest-SNR fluorescence microscopy data. The advantage of the presented approach is demonstrated by means of four data sets: synthetic data for in-depth evaluation of the algorithm behavior; two data sets acquired for analysis of initial Ca2+ microdomains in T cells; and, to illustrate transferability of the methodical concept to different applications, one dataset depicting spontaneous Ca2+ signaling in jGCaMP7b-expressing astrocytes. To foster re-use and reproducibility, the source code is made publicly available.

bioinformatics↗