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Creasey, E. A.

Publications and source records attributed to Creasey, E. A..

4 recordsLinked to original sources
bioRxiv2024

The Ulcerative Colitis-Associated Gene NXPE1 Catalyzes Glycan Modifications on Colonic Mucin

Colonic mucus forms a first line of defense against bacterial invasion while providing nutrition to support coinhabiting microbes in the gut. Mucus is composed of polymeric networks of mucin proteins, which are heavily modified post-translationally. The full compendium of enzymes responsible for these modifications and their roles in health and disease remain incompletely understood. Herein we determine the biochemical function of NXPE1, a gene implicated in ulcerative colitis (UC), and demonstrate that it encodes an acetyltransferase that modifies mucin glycans. Specifically, NXPE1 utilizes acetyl-CoA to regioselectively modify the mucus sialic acid, 5-N-acetylneuraminic acid (Neu5Ac), at the 9-OH group to generate 9-O-acetylated Neu5Ac (Neu5,9Ac2). We further demonstrate that colonic organoids derived from donors harboring the missense variant NXPE1 G353R, which is protective against UC, exhibit severely impaired acetylation of Neu5Ac on mucins. Together, our findings support a model in which NXPE1 masks the alcohols of mucus sialoglycans via acetylation, which is important for modulating mucus barrier properties that limit interactions with commensal microbes.

immunology↗
bioRxiv2020

The schizophrenia-associated variant in SLC39A8 alters N-glycosylation in the mouse brain

A missense mutation (A391T) in the manganese transporter SLC39A8 is strongly associated with schizophrenia in genomic studies, though the molecular connection to the brain remains hypothetical. Human carriers of A391T have reduced serum manganese, altered plasma glycosylation, and brain MRI changes consistent with altered metal transport. Here, using a knock-in mouse model homozygous for A391T, we show that the schizophrenia-associated variant changes protein glycosylation in the brain. N-linked glycosylation was most significantly impaired, with effects differing between regions. RNAseq analysis showed negligible regional variation, consistent with changes in the activity of glycosylation enzymes rather than gene expression. Finally, nearly one third of detected glycoproteins were differentially N-glycosylated in the cortex, including members of several pathways previously implicated in schizophrenia such as cell adhesion molecules and neurotransmitter receptors. These findings provide a mechanistic link between a risk allele and biochemical changes in the brain, furthering our molecular understanding of the pathophysiology of schizophrenia.

neuroscience↗
bioRxiv2020

SdhA blocks disruption of the Legionella-containing vacuole by hijacking the OCRL phosphatase

Legionella pneumophila grows intracellularly within a replication vacuole via action of Icm/Dot-secreted proteins. One such protein, SdhA, maintains the integrity of the vacuolar membrane, thereby preventing cytoplasmic degradation of bacteria. We show here that SdhA binds and blocks the action of OCRL (OculoCerebroRenal syndrome of Lowe), an inositol 5-phosphatase pivotal for controlling endosomal dynamics. OCRL depletion resulted in enhanced vacuole integrity and intracellular growth of a sdhA mutant, consistent with OCRL participating in vacuole disruption. Overexpressed SdhA altered OCRL function, enlarging endosomes, driving endosomal accumulation of PI(4,5)P2, and interfering with endosomal trafficking. SdhA interrupted Rab GTPase-OCRL interactions by binding to the OCRL ASH domain, without directly altering OCRL 5-phosphatase activity. The Legionella vacuole encompassing the sdhA mutant accumulated OCRL and endosomal antigen EEA1, consistent with SdhA blocking accumulation of OCRL-containing endosomal vesicles. Therefore, SdhA hijacking of OCRL is associated with blocking trafficking events that disrupt the pathogen vacuole.

microbiology↗