Biology subjects

O'Grady, K.

Publications and source records attributed to O'Grady, K..

3 recordsLinked to original sources

bioRxiv2022

Gut commensal bacteria enhance pathogenesis of a tumorigenic murine retrovirus

The influence of the microbiota on viral transmission and replication is well appreciated. However, its impact on retroviral pathogenesis outside of transmission/replication control remained unknown. Using Murine Leukemia Virus (MuLV), we found that some commensal bacteria promoted the development of leukemia induced by this retrovirus. The promotion of leukemia development by commensals was due to suppression of the adaptive immune response through upregulation of several negative regulators of immunity. These negative regulators included Serpinb9b and Rnf128, which are associated with a poor prognosis of some spontaneous human cancers. Upregulation of Serpinb9b was mediated by sensing of bacteria by NOD1/NOD2/RIPK2 pathway. This work describes a novel mechanism by which the microbiota enhances tumorigenesis within gut-distant organs and points at potential new targets for cancer therapy.

microbiology↗

bioRxiv2021

Influence of substrate stiffness on barrier function in an iPSC-derived in vitro blood-brain barrier model

IntroductionVascular endothelial cells respond to a variety of biophysical cues such as shear stress and substrate stiffness. In peripheral vasculature, extracellular matrix (ECM) stiffening alters barrier function, leading to increased vascular permeability in atherosclerosis and pulmonary edema. The effect of ECM stiffness on blood-brain barrier (BBB) endothelial cells, however, has not been explored. To investigate this topic, we incorporated hydrogel substrates into an in vitro model of the human BBB. MethodsInduced pluripotent stem cells were differentiated to brain microvascular endothelial-like (BMEC-like) cells and cultured on hydrogel substrates of varying stiffness. Cellular changes were measured by imaging, functional assays such as transendothelial electrical resistance (TEER) and p-glycoprotein efflux activity, and bulk transcriptome readouts. ResultsThe magnitude and longevity of TEER in iPSC-derived BMEC-like cells is enhanced on compliant substrates. Quantitative imaging shows that BMEC-like cells form fewer intracellular actin stress fibers on substrates of intermediate stiffness (20 kPa relative to 1 kPa and 150 kPa). Chemical induction of actin polymerization leads to a rapid decline in TEER, agreeing with imaging readouts. P-glycoprotein activity is unaffected by substrate stiffness. Modest differences in RNA expression corresponding to specific signaling pathways were observed as a function of substrate stiffness. ConclusionsiPSC-derived BMEC-like cells exhibit differences in passive but not active barrier function in response to substrate stiffness. These findings may provide insight into BBB dysfunction during neurodegeneration, as well as aid in the optimization of more complex threedimensional neurovascular models utilizing compliant hydrogels.

bioengineering↗

bioRxiv2019

Rapid Alkalinization Factor (RALF) gene family genomic structure and transcriptional regulation during host-pathogen crosstalk in Fragaria vescaand Fragariax ananassastrawberry

Rapid Alkalinization Factor (RALF) are cysteins-rich peptides ubiquitous in plant kingdom. They play multiple roles as hormone signals, starting from root elongation, cell growth, pollen tube development and fertilization. Their involvement in host-pathogen crosstalk as negative regulator of immunity in Arabidopsis has also been recognized. In addition, RALF peptides are secreted by different fungal pathogens as effectors during early stages of infections. Campbell and Turner previously identified nine RALF genes in F. vesca v1 genome. Here, based on the recent release of Fragaria x ananassa genome and F. vesca reannotation, we aimed to characterize the genomic organization of the RALF gene family in both type of strawberry species according to tissue specific expression and homology with Arabidopsis. We reveal the presence of 13 RALF genes in F. vesca and 50 in Fragaria x ananassa, showing a non-homogenous localization of genes among the different Fragaria x ananassa subgenomes associated with their different TE element contents and genome remodeling during evolution. Fragaria x ananassa RALF genes expression inducibility upon infection with C. acutatum or B. cinerea was assessed and showed that, among fruit expressed RALF genes, FaRALF3-1 was the only one upregulated after fungal infection. In silico analysis and motif frequency analysis of the putative regulatory elements upstream of the FaRALF3 gene was carried out in order to identify distinct pathogen inducible elements. Agroinfiltration of strawberry fruit with 5 deletion constructs of the FaRALF3-1 promoter identified a region required for FaRALF3 expression in fruit, but did not identify a region responsible for fungal induced expression.

plant biology↗