Biology subjects

Till, A.

Publications and source records attributed to Till, A..

3 recordsLinked to original sources

bioRxiv2025

Protracted fate acquisition and epigenetic de-aging during induced neural stem cell conversion of human blood cells

Transcription factor-based direct conversion of somatic cells represents an interesting avenue for generating induced neural stem cells (iNSCs) from peripheral blood without transit through a pluripotent stage. While this paradigm has been shown to be associated with epigenetic de-aging, the dynamics of this process have remained unclear. Here, we used overexpression of the two reprogramming factors SOX2 and cMYC to generate iNSC from erythroid progenitors of donors ranging from neonatal to 101 years of age. Using an epigenetic clock algorithm, we corroborated our previous finding that iNSCs generated from aged donors show pronounced epigenetic de-aging, preserving around 13 % and 5 % of the original donor age at low and high passages, respectively. Studying the dynamic of epigenetic de-aging during iNSC conversion across time, we found that this process is largely protracted, continuing for several weeks and even beyond forced neuronal differentiation of iNSCs. Transcriptomic differences between young and old donor-derived iNSCs dissipate with extended time in conversion, too. Concordant with this observation, established iNSC lines lack age-associated cellular hallmarks, similar to induced pluripotent stem cells and their derivatives. Interestingly, time course analysis of DNA methylation and RNA sequencing data revealed that acquisition of a bona fide NSC signature extends greatly beyond the time point when proliferative PAX6-positive iNSCs emerge. The unexpected slow dynamics of these processes makes iNSC conversion an attractive model for dissecting the mechanisms underlying somatic transdifferentiation and de-aging. Statement of Ethical ApprovalsThe collection of human somatic material (i.e., blood) from healthy donors for iPSC reprogramming and iNSC conversion was conducted in accordance with German law and approved by the Ethics Committee of the University of Bonn Medical Center (approval number: 275/08). All subjects gave written informed consent.

neuroscience↗

bioRxiv2024

From Planning Stage To FAIR Data: A Practical Metadatasheet For Biomedical Scientists

Datasets consist of measurement data and metadata. Metadata provides context, essential for understanding and (re-)using data. Various metadata standards exist for different methods, systems and contexts. However, relevant information resides at differing stages across the data-lifecycle. Often, this information is defined and standardized only at publication stage, which can lead to data loss and workload increase. In this study, we developed Metadatasheet, a metadata standard based on interviews with members of two biomedical consortia and systematic screening of data repositories. It aligns with the data-lifecycle allowing synchronous metadata recording within Microsoft Excel, a widespread data recording software. Additionally, we provide an implementation, the Metadata Workbook, that offers user-friendly features like automation, dynamic adaption, metadata integrity checks, and export options for various metadata standards. By design and due to its extensive documentation, the proposed metadata standard simplifies recording and structuring of metadata for biomedical scientists, promoting practicality and convenience in data management. This framework can accelerate scientific progress by enhancing collaboration and knowledge transfer throughout the intermediate steps of data creation.

bioinformatics↗

bioRxiv2022

Group A Streptococcus Induces Lysosomal Dysfunction in THP-1 Macrophages

The human-specific bacterial pathogen Group A Streptococcus (GAS) is a significant cause of morbidity and mortality. Macrophages are important to control GAS infection, but previous data indicate that GAS can persist in macrophages. In this study, we detail the molecular mechanisms by which GAS survives in THP-1 macrophages. Our fluorescence microscopy studies demonstrate that GAS are readily phagocytosed by macrophages, but persist within phagolysosomes. These phagolysosomes are not acidified, which is in agreement with our findings that GAS cannot survive in low pH environments. We find that the secreted pore-forming toxin Streptolysin O (SLO) perforates the phagolysosomal membrane, allowing leakage of not only protons, but large proteins including the lysosomal protease cathepsin B. Additionally, GAS blocks the activity of vacuolar ATPase (v-ATPase) to prevent acidification of the phagolysosome. Thus, while GAS does not inhibit fusion of the lysosome with the phagosome, it has multiple mechanisms to prevent proper phagolysosome function, allowing for persistence of the bacteria within the macrophage. This has important implications for not only the initial response but the overall functionality of the macrophages, which may lead to the resulting pathologies in GAS infection. Our data suggests that therapies aimed at improving macrophage function may positively impact patient outcomes in GAS infection.

microbiology↗