Biology subjects

Whitelegge, J.

Publications and source records attributed to Whitelegge, J..

3 recordsLinked to original sources

bioRxiv2026

Tear Proteomics Reveals RAGE and NLRP3 Inflammasome Pathway Activation in Lacrimal Glands of a Sjögren's Disease Mouse Model

PurposeTo characterize tear proteome changes in male non-obese diabetic (NOD) mice with Sjogrens disease (SjD)-like autoimmune dacryoadenitis and determine whether identified tear proteins are associated with lacrimal gland (LG) pathogenesis. MethodsTears were collected from 14-week-old male NOD mice and age-matched male BALB/c controls and analyzed by tandem mass tag (TMT)-based liquid chromatography tandem mass spectrometry (LC-MS/MS). Differentially expressed proteins (DEPs) were defined using adjusted P < 0.05 and absolute fold change > 1.5. Functional enrichment analysis was performed using Enrichr. Selected upregulated DEPs were further examined in tear and LG samples from independent mouse cohorts using Western blotting, immunofluorescence, and RT-qPCR. ResultsA total of 142 proteins were quantified across all tear samples. Hierarchical clustering and principal component analysis (PCA) separated NOD from BALB/c tear proteomes. A total of 41 proteins were differentially expressed in NOD mouse tears (33 increased, 8 decreased). Increased tear proteins were enriched in immune and inflammatory responses, secretory compartments, RAGE receptor binding, glutathione metabolism, oxidative stress, and redox regulation. S100A8/A9, GSTO1-1, Gal-3, and pIgR/secretory component (SC) were increased in both NOD mouse tears and LG. In NOD LG, increased S100A8/A9 was accompanied by elevated RAGE, whereas increased GSTO1-1 was associated with increased NLRP3, cleaved caspase-1, cleaved gasdermin, cleaved IL-1{beta}, and increased Il1b, Il18, and Il18r gene expression. ConclusionsMale NOD mouse tears contain disease-related proteins reflecting pathological inflammatory and epithelial changes in the LG including increased RAGE signaling, NLRP3 inflammasome activation, and altered epithelial transcytosis.

immunology↗

bioRxiv2024

Ethanolamine-induced assembly of microcompartments is required for Fusobacterium nucleatum virulence

Many bacteria metabolize ethanolamine as a nutrient source through cytoplasmic organelles named bacterial microcompartments (BMCs). Here we investigated the molecular assembly, regulation, and function of BMCs in Fusobacterium nucleatum - a Gram-negative oral pathobiont that is associated with adverse pregnancy outcomes. The F. nucleatum genome harbors a conserved ethanolamine utilization (eut) locus with 21 genes that encode several putative BMC shell proteins and a two-component signal transduction system (TCS), in addition to the enzymes for ethanolamine transport and catabolism. We show that the expression of most of these genes as well as BMC formation is highly increased in wild type fusobacteria when cultured in the presence of ethanolamine as a nutrient source. Deletion of the response regulator EutV eliminated this induction of eut mRNAs and BMCs, thus demonstrating that BMC formation is transcriptionally regulated by the TCS EutV-EutW in response to ethanolamine. Mass spectrometry of isolated BMCs unveiled the identity of the constituent proteins EutL, EutM1, EutM2, and EutN. Consistent with the role of these proteins in BMC assembly and metabolism, deletion of eutN, eutL/eutM1/eutM2, or eutL/eutM1/eutM2/eutN not only affected BMC formation, but also ethanolamine utilization, causing cell growth defects with ethanolamine as nutrient. BMCs also assembled in fusobacteria cultured with placental cells or the culture media, a process that is dependent on the BMC shell proteins. Significantly, we show that the eutN mutant is defective in inducing preterm birth in a mouse model. Together, these results establish that BMC-mediated metabolism of ethanolamine is critical for fusobacterial virulence. IMPORTANCEThe oral anaerobe Fusobacterium nucleatum can spread to distal internal organs, such as the colon and placenta, and thereby promote the development of colorectal cancer and induce preterm birth, respectively. Yet, how this opportunistic pathogen adapts to the various metabolically distinct host cellular niches remains poorly understood. We demonstrated here that this microbe assembles specialized metabolic organelles, termed bacterial microcompartments (BMCs), to utilize environmental ethanolamine (EA) as a key environmental nutrient source. The formation of F. nucleatum BMCs, containing BMC shell proteins EutLM1M2N, is controlled by a two-component system, EutV-EutW, responsive to EA. Significantly, this ability of F. nucleatum to form BMCs in response to EA is crucial for its pathogenicity evidenced by the fact that the genetic disruption of BMC formation reduces fusobacterial virulence in a mouse model of preterm birth.

microbiology↗

bioRxiv2019

Physiological and Evolutionary Implications of Tetrameric Photosystem I in Cyanobacteria

Photosystem I (PSI) were reported as trimeric complexes in most characterized cyanobacteria, yet monomers in plants and algae PSI. Recent reports on tetrameric PSI raised questions regarding its structural basis, physiological role, phylogenetic distribution and evolutionary significance. In this study, by examining PSI in 61 cyanobacteria, we show that tetrameric PSI, correlating with a unique psaL gene and genomic structure, is widespread in the heterocyst-forming cyanobacteria and their close relatives. Physiological studies on these cyanobacteria revealed that tetrameric PSI is favored under high light, with an increased content of novel PSI-bound carotenoids (myxoxanthophyll, canthaxanthan and echinenone). Together this work suggests that tetrameric PSI is an adaptation to high light, along with results showing that change in PsaL leads to trimeric PSI monomerization, supporting the hypothesis of tetrameric PSI being the evolutionary intermediate in the transition from cyanobacterial trimeric PSI to monomeric PSI in plants and algae.

evolutionary biology↗