Biology subjects

Svensson, M.

Publications and source records attributed to Svensson, M..

3 recordsLinked to original sources

bioRxiv2024

ATF4 orchestrates IL-1α-induced senescence in adult neural stem cells

Adult neural stem cells (NSC) are a potential source for the regeneration of damaged tissue during neuropathological conditions, but much remains unexplored. In an attempt to study the influence of neuroinflammation on NSCs, we generated a transgenic reporter rat strain that expresses the Discosoma sp. red (DsRed) fluorophore in NSCs and subjected it to traumatic brain injury (TBI). Transcriptomic analysis of NSCs isolated from TBI revealed an enrichment of stress response genes that pertained to endoplasmic reticulum (ER) stress and integrated stress response (ISR). Downstream analysis on NSC cultures pinpointed IL-1 as a trigger of ISR in these cells. At concentration levels similar to the ones measured post-TBI in rats, IL-1 induced the translation of activating transcription factor 4 (ATF4), an ISR master regulator. Further, ATF4 was necessary for the IL-1 -dependent induction of a senescent profile in NSCs, which included a metabolic shift towards glycolysis, induction of senescence-associated secretory phenotype, SASP, and cell cycle arrest. In summary, the ISR/ATF4 pathway seems to play a major role in NSC function during neuroinflammation and provides a therapeutic tool for protecting the NSC pool during these conditions.

neuroscience↗

bioRxiv2023

Alpha-toxin elicited CX3CL1-release via ADAM10 in Staphylococcus aureus pneumoniaimpairs bactericidal function of human monocytes

Staphylococcus aureus is an important human pathogen causing severe invasive infections. Pathogenesis is attributed to a wide array of virulence factors, including several potent exotoxins such as the pore-forming alpha-toxin. In this study, we found that patients with S. aureus respiratory tract infections had elevated CX3CL1 levels in airway fluid and plasma. Using humanized organotypic lung models, we observed that stimulation of lung epithelium with alpha-toxin induce an intensified CX3CL1 expression apically in the epithelium as well as the release of CX3CL1. Blocking alpha-toxin or ADAM10 activity in organotypic lung using an alpha-toxin-blocking antibody or a specific ADAM-10 inhibitor confirmed their role in modulating CX3CL1 cleavage and release. Analyses of CD14+ human monocytes in combination with a CX3CR1 inhibitor revealed that alpha-toxin-mediated CX3CL1 release induce CX3CL1-dependent chemotaxis. In line with these data, lung tissue from patients with S. aureus respiratory tract infection showed elevated CX3CL1 and CD14 staining as compared to tissue from patients with non-infectious lung diseases. Functional studies of monocytes showed that CX3CL1 released by lung models resulted in upregulated CD83 and downregulated CD86, as well as impaired killing of phagocytosed S. aureus. Furthermore, stimulation of monocytes with soluble CX3CL1 hampered their reactive-oxygen and nitric-oxide production. Taken together, our data show that S. aureus triggers the release of lung epithelial CX3CL1; a process found to be dependent on the alpha-toxins effect on ADAM10 mediating cytotoxicity and resulting in impaired monocyte phagocytic killing. Hence, we identify an immunomodulatory effect of alpha-toxin involving the CX3CL1-ADAM10 axis extending beyond the cytolysis function.

microbiology↗

bioRxiv2023

Bamboozle: A bioinformatic tool for identification and quantification of intraspecific barcodes

Evolutionary changes in populations of microbes, such as microalgae, cannot be traced using conventional metabarcoding loci as they lack intraspecific resolution. Consequently, selection and competition processes amongst strains of the same species cannot be resolved without elaborate isolation, culturing, and genotyping efforts. Bamboozle, a new bioinformatic tool introduced here, scans a species entire genome and identifies allele-rich barcodes that enable direct identification of different strains from a common population, and a single DNA sample, using amplicon sequencing. We demonstrate its usefulness by identifying hypervariable barcoding loci (<500 bp) from genomic data in two microalgal species, the diploid diatom Skeletonema marinoi, and the haploid chlorophyte Chlamydomonas reinhardtii. Across the genomes, only 26 loci capable of resolving all available strains genotypes were identified, all of which are within protein-coding genes of variable metabolic function. Single nucleotide polymorphisms (SNPs) provided the most reliable genetic markers, and amongst 55 strains of S. marinoi, three 500 bp loci contained, on average, 46 SNPs, 103 unique alleles, and displayed 100% heterozygosity. The prevalence of heterozygosity was identified as a novel opportunity to improve strain quantification and detect false positive artefacts during denoising of amplicon sequences. Finally, we illustrate how metabarcoding of a single genetic locus can be used to track strain abundances of 58 strains of S. marinoi in an artificial selection experiment. As future genomics datasets become available and DNA sequencing technologies develop, Bamboozle has flexible user settings enabling optimal barcodes to be designed for other species and applications.

evolutionary biology↗