Oates, C. | Search bioRxiv

bioRxiv2024

High fat diet induces differential age- and gender-dependent changes in neuronal function linked to redox stress.

The prevalence of neurodegenerative diseases, such as Alzheimers disease and Parkinsons disease, is steadily increasing, posing significant challenges to global healthcare systems. Emerging evidence suggests that dietary habits, particularly consumption of high-fat diets specify which fats, may play a pivotal role in the development and progression of neurodegenerative disorders. Moreover, several studies have shed light on the intricate communication between the gut and the brain, known as the gut-brain axis and its involvement in neurodegenerative processes. This study aims to assess the effects of a high-fat dietary intake on various aspects of neuronal function during aging and following gender separation to help understand the potential contributions of diet to neuronal function. To investigate the effects of a high-fat diet, Drosophila melanogaster was used and exposed to standard normal food diet (NF) and high-fat diet (HF). Adults were grouped at 10 and 45 days of age in male and female flies reared under the same conditions. Multiple assays were conducted, showing differential gender- and HF diet-induced oxidative stress levels as determined by malondialdehyde (MDA) measurements, enhanced caspase-3 expression and reduced climbing activity. Adult lifespan under both dietary conditions was unchanged but odour-associated learning ability was reduced in larvae reared in a HF diet. This is the first study to characterise effects of diet on neuronal phenotypes in an age- and gender-specific manner in a Drosophila model. Our findings suggest a HF diet induces differential forms of neuronal dysfunction with age and sex-specific outcomes, characterised by enhanced oxidative stress and cell death which impacts on neuronal and behavioural functions.

neuroscience↗

bioRxiv2019

Loss of O-linked protein glycosylation in Burkholderia cenocepacia impairs biofilm formation and siderophore production via alteration of quorum sensing regulation

O-linked protein glycosylation is a conserved feature of the Burkholderia genus. For Burkholderia cenocepacia, the addition of the trisaccharide {beta}-Gal-(1,3)--GalNAc-(1,3)-{beta}-GalNAc to membrane exported proteins is required for virulence and resistance to environmental stress. However, the underlying causes of the defects observed in the absence of glycosylation are unclear. This study demonstrates that the global B. cenocepacia proteome undergoes dramatic changes consistent with alterations in global transcriptional regulation in the absence of glycosylation. Using luciferase reporter assays and DNA cross-linking analysis, we confirm the repression of the master quorum sensing regulon CepR/I in response to the loss of glycosylation, which leads to the abolition of biofilm formation, defects in siderophore production, and reduced virulence. The abundance of most of the known glycosylated proteins did not significantly change in the glycosylation-defective mutants except for BCAL1086 and BCAL2974, which were found in reduced amount, suggesting they could be degraded. However, the loss of these two proteins was not responsible for driving the proteomic alterations, as well as for reduced virulence and siderophore production. Together, our results show that loss of glycosylation in B. cenocepacia results in a global cell reprogramming via alteration of the CepR/I regulon, which cannot be explained by the abundance changes in known B. cenocepacia glycoproteins.\n\nIMPORTANCEProtein glycosylation is increasingly recognised as a common protein modification in bacterial species. Despite this commonality our understanding of the role of most glycosylation systems in bacterial physiology and pathogenesis is incomplete. In this work, we investigated the effect of the disruption of O-linked glycosylation in the opportunistic pathogen Burkholderia cenocepacia using a combination of proteomic, molecular and phenotypic assays. We find that in contrast to recent findings on the N-linked glycosylation systems of Campylobacter jejuni, O-linked glycosylation does not appear to play a role in proteome stabilization of most glycoproteins. Our results reveal that virulence attenuation observed within glycosylation-null B. cenocepacia strains are consistent with alteration of the master virulence regulator CepR. The repression of CepR transcription and its associated phenotypes support a model in which the virulence defects observed in glycosylation-null strains are at least in part due to transcriptional alteration and not the direct result of the loss of glycosylation per-se. This research unravels the pleotropic effects of O-linked glycosylation in B. cenocepacia, demonstrating that its loss does not simply affect the stability of the glycoproteome, but also interferes with transcription and the broader proteome.

microbiology↗