Biology subjects

Zimmermann, O.

Publications and source records attributed to Zimmermann, O..

3 recordsLinked to original sources

bioRxiv2026

A cell death-independent role for MLKL in TGF-β receptor recycling in Marfan syndrome

Marfan syndrome (MFS) causes thoracic aortic aneurysm through mutations in the fibrillin-1 gene and subsequent dysregulated TGF-{beta} signalling. Mixed lineage kinase domain-like protein (MLKL) executes necroptosis after RIPK3-dependent phosphorylation, but also functions in endosomal trafficking. Here we show that MLKL phosphorylation sustains TGF-{beta} receptor recycling and aortic wall integrity without causing cell death. Phosphorylation-dead MLKLS345A/S347A (MlklAA) mice developed aortic root dilation with disorganised collagen architecture and a secretory-pathway proteomic signature. Crossing them with Fbn1C1039G/+ MFS mice aggravated aortic dilation, disrupted collagen fibril ultrastructure and prolyl/lysyl hydroxylation, and caused lethal rupture under angiotensin II. Complete MLKL deficiency reproduced this phenotype. Phosphorylated MLKL was increased in MFS aortas, yet cleaved caspase-3, TUNEL positivity, smooth muscle cell content and leukocyte infiltration were unchanged. In smooth muscle cells, MLKL depletion dysregulated collagen-modifying enzymes, altered TGF-{beta}-driven matrix remodelling and impaired RAB11-dependent TGF{beta}R1 recycling. These findings suggest that phosphorylation-dependent, non-lytic functions of MLKL may contribute to the maintenance of thoracic aortic integrity in MFS.

cell biology↗

bioRxiv2023

EphrinA5 regulates cell motility by modulating the targeting of DNMT1 to the Ncam1 promoter via lncRNA/DNA triplex formation

Cell-cell communication is mediated by membrane receptors and their cognate ligands, such as the Eph/ephrin system, and dictates physiological processes, including cell proliferation and migration. However, whether and how Eph/ephrin signaling culminates in transcriptional regulation is largely unknown. Epigenetic mechanisms are key for integrating external "signals", e.g., from neighboring cells, into the transcriptome. We have previously reported that ephrinA5 stimulation of immortalized cerebellar granule (CB) cells elicits transcriptional changes of lncRNAs and protein-coding genes. LncRNAs represent important adaptors for epigenetic writers through which they regulate gene expression. Here, we investigate the interaction of lncRNA with protein-coding genes by the combined power of in silico modeling of RNA/DNA interactions and respective wet lab approaches, in the context of ephrinA5-dependent regulation of cellular motility. We found that Snhg15, a cancer-related lncRNA, forms a triplex structure with the Ncam1 promoter and interacts with DNMT1. EphrinA5 stimulation leads to reduced Snhg15 expression, diminished Snhg15/DNMT1 interaction and decreased DNMT1 association with the Ncam1 promoter. These findings can explain the attenuated Ncam1 promoter methylation and elevated Ncam1 expression that in turn elicits decreased cell motility of CB cells. Hence, we propose that ephrinA5 influences gene transcription via lncRNA-targeted DNA methylation underlying the regulation of cellular motility.

molecular biology↗

bioRxiv2019

Global genomic population structure of Clostridioides difficile

Clostridioides difficile is the primary infectious cause of antibiotic-associated diarrhea. Local transmissions and international outbreaks of this pathogen have been previously elucidated by bacterial whole-genome sequencing, but comparative genomic analyses at the global scale were hampered by the lack of specific bioinformatic tools. Here we introduce EnteroBase, a publicly accessible database (http://enterobase.warwick.ac.uk) that automatically retrieves and assembles C. difficile short-reads from the public domain, and calls alleles for core-genome multilocus sequence typing (cgMLST). We demonstrate that the identification of highly related genomes is 89% consistent between cgMLST and single-nucleotide polymorphisms. EnteroBase currently contains 13,515 quality-controlled genomes which have been assigned to hierarchical sets of single-linkage clusters by cgMLST distances. Hierarchical clustering can be used to identify populations of C. difficile at all epidemiological levels, from recent transmission chains through to pandemic and endemic strains, and is largely compatible with prior ribotyping. Hierarchical clustering thus enables comparisons to earlier surveillance data and will facilitate communication among researchers, clinicians and public-health officials who are combatting disease caused by C. difficile.

microbiology↗