Biology subjects

Garcia-Weber, D.

Publications and source records attributed to Garcia-Weber, D..

3 recordsLinked to original sources

bioRxiv2024

Differential translocation of bacteriophages across the intestinal barrier in health and Crohn's disease

Impaired intestinal barrier function is a major feature of Crohns disease (CD), leading to exacerbated inflammation in response to the microbiota. In this context, the translocation of intestinal bacteriophages (phages) and their effects on the host have been little investigated. We used phage fluorescence imaging coupled with ex-vivo and in-vitro models that mimic physiological and inflammatory conditions and found that phages can translocate across the intestinal barrier without disrupting its integrity. Although the translocation rate across the intestinal epithelium depended on phage morphology and the condition of the barrier, these factors did not influence the crossing of phage across the vascular endothelium. Virome analysis confirmed that viral sequences shared between blood and stool samples are more abundant in CD patients than healthy subjects, indicating that a barrier defect facilitates phage translocation from the gut to the bloodstream.

cell biology↗

bioRxiv2023

In vitro ALPK1 kinase assay reveals new insights into ADP-heptose sensing pathway and kinase activity of disease-associated ALPK1 mutants

Alpha-protein kinase 1 (ALPK1) is a pathogen recognition receptor that detects ADP-heptose (ADPH), a lipopolysaccharide biosynthesis intermediate, recently described as a pathogen-associated molecular pattern in Gram-negative bacteria. ADPH binding to ALPK1 activates its kinase domain and triggers TIFA phosphorylation on threonine 9. This leads to the assembly of large TIFA oligomers called TIFAsomes, activation of NF-{kappa}B and pro-inflammatory gene expression. Furthermore, mutations in ALPK1 are associated with inflammatory syndromes and cancers. While this kinase is of growing medical interest, only few tools are available to characterize its activity. Here, we describe a versatile non-radioactive ALPK1 in vitro kinase assay based on protein thiophosphorylation. We confirm that ALPK1 phosphorylates TIFA T9 and show that T2, T12 and T19 are also weakly phosphorylated by ALPK1. Interestingly, we find that ALPK1 itself is phosphorylated in response to ADPH recognition during Shigella flexneri and Helicobacter pylori infection and that disease-associated ALPK1 mutants exhibit altered kinase activity. In particular, T237M and V1092A mutations associated with ROSAH syndrome and spiradenoma/spiradenocarcinoma respectively, exhibit enhanced ADPH-induced kinase activity and constitutive assembly of TIFAsomes. Altogether, this study provides new insights into the ADPH sensing pathway and a new tool for measuring the activity of ALPK1.

immunology↗

bioRxiv2018

ADP-heptose is a pathogen-associated molecular pattern of Shigella flexneri infection

During an infection, the detection of pathogens is mediated through interactions between pathogen-associated molecular patterns (PAMPs) and pathogen recognition receptors. {beta}-Heptose 1,7-bisphosphate ({beta}HBP), a metabolite of the lipopolysaccharide (LPS) biosynthesis pathway, was recently identified as a PAMP of gram-negative bacteria. It was reported that {beta}HBP sensing leads within minutes to oligomerization of the protein TIFA, a mechanism controlling NF-{kappa}B activation and pro-inflammatory gene expression. Here, we compared the ability of chemically synthesized {beta}HBP and Shigella flexneri lysate to induce TIFA oligomerization in epithelial cells. In contrast to lysate, we found that {beta}HBP fails to trigger rapid oligomerization of TIFA. {beta}HBP only induces delayed signaling, suggesting that it has to be processed intracellularly to induce inflammation. By dissecting the LPS biosynthesis pathway with deletion mutants and functional complementation experiments, we show that ADP-D-glycero-{beta}-D-manno-heptose and ADP-L-glycero-{beta}-D-manno-heptose are the bacterial metabolites responsible for rapid TIFA oligomerization, and that they strongly induce interleukin-8 expression during S. flexneri infection. Altogether, our results rule out a major role of {beta}HBP in S. flexneri infection and identify ADP-heptose as a new PAMP.

immunology↗