Biology subjects

Sylvius, N.

Publications and source records attributed to Sylvius, N..

4 recordsLinked to original sources

bioRxiv2026

The single nucleotide polymorphism rs1053230 modulates kynurenine 3-monooxygenase stability and is associated with cognitive and mood phenotypes

BackgroundThe single nucleotide polymorphism (SNP) rs1053230 within the kynurenine 3-monooxygenase (KMO) gene encodes either an arginine (CGC) or cysteine (TGC) at amino acid residue 452. The rs1053230 genotype is associated with alterations in KMO expression and activity, and impaired cognition. Additionally, KMO intronic SNP rs2275163 is associated with schizophrenia endophenotypes. However, the direct functional consequences of these SNPs on KMO function have never been investigated. MethodsHere we performed the first in vitro cell-based examination of the rs1053230 genotype on KMO expression, activity, cellular localisation and KMO-protein interactions, as well as examination of the effects of rs1053230 on schizophrenia-relevant clinical measures. We also examined the effects of rs2275163 genotype on KMO pre-mRNA stability and alternative splicing. ResultsHEK293T cells expressing KMO-Arg452 or KMO-Cys452 with a red fluorescent protein (RFP) tag produced equivalent levels of KMO mRNA, protein and enzymatic activity, and localised to mitochondria to the same extent. However, cycloheximide-mediated inhibition of protein translation revealed a striking reduction in protein stability of KMO-Arg452-RFP. KMO-RFP-trap pull-down followed by tandem liquid-chromatography-mass spectrometry (LC-MS/MS) identified dramatic differences in protein partners between KMO variants. Indeed, gene ontology-term enrichment analysis revealed that terms associated with synaptic function were more highly enriched amongst KMO-Cys452 interacting proteins. rs1053230 genotype was found to associate with chronic, trait-like depressive mood symptoms in patients. rs2275163 genotype had no effect on KMO pre-mRNA. ConclusionsDifferences in protein stability and protein-protein interactions may underlie the mechanisms by which the KMO rs1053230 genotype influences neuronal function, leading to cognitive differences in psychiatric conditions.

molecular biology↗

bioRxiv2026

Identification of a miRNA signature for schizophrenia in plasma-derived extracellular vesicles

Background and Hypothesis: Extracellular vesicles (EVs) are phospholipid bilayer vesicles released from cells containing proteins, lipids and nucleic acids derived from the parent cell. Alterations in miRNA expression within blood-derived EVs have been proposed as potential biomarkers of disease. Specifically, identification of differentially expressed miRNAs in patients with schizophrenia (SZ) compared to healthy individuals could be used as a "miRNA signature" to aid in diagnosis and treatment. We therefore aimed to identify differentially expressed miRNAs in plasma-derived EVs between people living with SZ and healthy controls and to correlate miRNA levels with SZ-relevant clinical measures. Study Design: Plasma-derived EVs were isolated from a cohort of 33 individuals with SZ and 34 controls. Expression of 84 miRNAs was examined using a RT-qPCR panel. Study Results: Three miRNAs (hsa-miR-30e-5p, hsa-miR-103a-3p, hsa-miR-200b-3p) were differentially expressed between controls and patients. Gene ontology analysis of putative target genes shared between these miRNAs revealed enrichment of biological process terms related to neurogenesis. Analysis of miRNA expression compared to clinical measures showed that hsa-miR-103a-3p expression was associated with working memory and negatively correlated with white matter integrity in the combined patient-control group. Conclusions: We have identified a miRNA signature for SZ in plasma-derived EVs and shown for the first time that hsa-miR-30e-5p expression is significantly increased in plasma-derived EVs in SZ. The genetic links between differentially expressed miRNAs and neurogenesis, along with the correlations of hsa-miR-103a-3p with working memory and white matter integrity may underlie the functional importance of altered expression of the identified miRNAs in SZ.

genetics↗

bioRxiv2025

Examination of the enrichment of neuronal extracellular vesicles from cell conditioned media and human plasma using an anti-NCAM immunocapture bead approach

BackgroundThe isolation of neuron-derived extracellular vesicles (nEVs) from biofluids offers the potential to discover novel biomarkers to aid in diagnosis and treatment of psychiatric and neurodegenerative diseases. A few studies have used anti-NCAM antibody-bead-based immunocapture to enrich nEVs from plasma, some with little method validation. We therefore examined in detail this method for nEV enrichment. MethodsEVs were isolated from SH-SY5Y cell-conditioned media by precipitation, or from plasma using size exclusion chromatography. EVs were characterised using nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and immunoblot analysis. SH-SY5Y-EVs were incubated with anti-NCAM immunocapture beads and examined by flow cytometry, immunoblot analysis and scanning electron microscopy (SEM). Immunocaptured plasma-derived EVs were examined using a sensitive NCAM ELISA, SEM and qPCR for miRNAs. ResultsCharacterisation of SH-SY5Y-derived and plasma-derived EVs revealed the expected size distributions of EVs using NTA, the presence of EV markers using immunoblot analysis, and a cup-shaped morphology using TEM. Anti-NCAM beads, but not anti-L1CAM or IgG beads, captured NCAM-positive SH-SY5Y-EVs as shown by flow cytometry and immunoblot analysis. Both SH-SY5Y and plasma-derived EVs were visualised on the surface of anti-NCAM immunocapture beads using SEM. A sensitive NCAM ELISA detected NCAM antigen in plasma-derived EVs immunocaptured on anti-NCAM beads. qPCR analysis of plasma-derived EVs detected many miRNAs in total plasma-EVs with high expression of hsa-miR-16-5p, hsa-miR-451a and hsa-miR-126-3p. However, only between two and seven miRNAs were detected in EVs captured on anti-NCAM-beads from three blood donors. Finally, tissue distribution analysis of miRNAs from plasma-derived EVs on anti-NCAM beads revealed that these miRNAs are enriched in tissues or organs such as blood vessels, lung, bone, thyroid and heart, but were not enriched for brain-derived miRNAs. Discussion: This study indicates that anti-NCAM beads can efficiently enrich NCAM-positive EVs from cell culture conditioned media. However, nEV levels in small volumes of plasma are possibly too low to enable efficient anti-NCAM immunocapture for subsequent miRNA analysis. Other neuron-specific markers with high expression levels on nEVs are therefore required for processing patient samples where plasma volumes are likely to be low, and to allow efficient isolation of nEVs in clinical studies for subsequent cargo analysis.

cell biology↗

bioRxiv2022

Decreased miRNA-148a-3p expression in skeletal muscle of patients with chronic kidney disease

IntroductionSkeletal muscle wasting is a common complication of chronic kidney disease which leads to a loss of muscle function. The pathogenesis of skeletal muscle wasting is incompletely understood, which is preventing the development of targeted therapeutics. Recent evidence implicates miRNAs in the of skeletal muscle wasting. Our aim was to firstly examine miRNA profiles of CKD human skeletal muscle for the identification of aberrant expression patterns compared to a healthy control (HC) cohort, and secondly, investigate the role these miRNAs may play in inducing or promoting skeletal muscle atrophy using a novel human primary skeletal muscle cell model of CKD skeletal muscle. MethodsFor the comparison between CKD and HC populations, skeletal muscle biopsies were collected from the vastus lateralis of n=15 non-dialysis dependent CKD patients stage 3b-5 CKD patients, and n=15 healthy controls matched for age, gender and physical activity. n=5 biopsies from each group underwent next generation sequencing to obtain complete microRNA profiles in CKD vs HC cohorts, which were then validated in a separate cohort by PCR (N=10 in each group). A causative role in muscle wasting was determined by transfection of key microRNAs into a primary culture model of CKD skeletal muscle and changes in protein degradation determined by L-[3H]- phenylalanine release into the media. ResultsNext Generation Sequencing identified differential expression of 16 miRNAs in skeletal muscle of CKD patients versus controls, and PCR validation confirmed miRNA-148a-3p expression was significantly decreased in CKD patients. The reduced miRNA-148a-3p expression was also maintained in the primary culture model. Upon overexpression of miRNA-148a-3p in CKD myotubes, protein degradation rates were decreased non-significantly (p=0.28) by 16.3% compared to un-transfected CKD cells. ConclusionCKD was associated with a significant reduction in miRNA-148a-3p expression in skeletal muscle compared to non-CKD controls which was retained in our in vitro model. Overexpression of miRNA-148a-3p in primary skeletal myotubes non-significantly decreased muscle protein degradation by 16.3%. In order to determine the importance of miRNA-148a-regulation of protein degradation, a deeper understanding of miRNA-148a-3p targets and their associated pathways with respect to those dysregulated in skeletal muscle wasting is required.

molecular biology↗