Biology subjects

LeDuc, R.

Publications and source records attributed to LeDuc, R..

3 recordsLinked to original sources

bioRxiv2025

Dysregulated circRNA expression profile and associated miRNA sponging in abnormal lung development in congenital diaphragmatic hernia

RationaleCircular RNAs (circRNAs) can function as disease biomarkers. Their profile in abnormal lung development in congenital diaphragmatic hernia (CDH) is unknown. ObjectiveTo evaluate circRNA expression profile in CDH-associated abnormal lung development. MethodsWe profiled circRNAs in rat CDH and control lungs at embryonic day (E)15 and E21 by microarray. We validated identified circRNAs using back-splice junction amplicon sequencing, RT-qPCR, and in situ hybridization. We modified a CircRNA Function prediction Tool to predict CircRNA::micro(mi)RNA::messenger(m)RNA interactions and compared these with Oxford Nanopore RNA sequencing and existing human CDH datasets. Measurements and Main ResultsMicroarrays revealed a unique circRNA biosignature during CDH lung development. CircAnp32e was expressed in a sex-specific and spatiotemporal expression pattern in the epithelium at E15. The predicted mature sequence of circAnp32e overlapped >90% with its human orthologue. CircRNA::miRNA::mRNA interaction networks in E15 and E21 revealed enrichment in inflammation/infection, smooth muscle cell function, cell proliferation/cell cycle regulation, and response to hypoxia pathways. Parental genes of differential expressed circRNAs at E15 enriched pathways linked to cell proliferation/cell cycle/cancer, while at end-gestation, inflammation and cardiovascular processes were also overrepresented. Rat and human CDH lungs showed overlapping pathways with additional enrichment for RNA processing and protein binding/modification in humans. ConclusionA unique circRNA signature during abnormal lung development in CDH may mediate inflammatory responses, smooth-muscle-cell function, and cell proliferation regulation via miRNA sponging. Overlap of downstream pathways in rat and human CDH suggest conserved functions across species. CircRNAs may serve as biomarkers to guide prenatal management and mitigate aberrant lung development in CDH.

developmental biology↗

bioRxiv2025

Aggregation-prone alpha-synuclein proteoforms and dysregulated molecular signatures in the vermiform appendix of synucleinopathy patients

Synucleinopathies, including Parkinsons disease, are neurodegenerative diseases characterized by intracellular inclusions containing the amyloidogenic protein alpha-synuclein. While classically considered to be brain disorders, increasing evidence suggests involvement of the gut, with alpha-synuclein aggregates potentially propagating to the brain via the vagus nerve. Evidence also suggests that the vermiform appendix is particularly susceptible to alpha-synuclein aggregation, and appendectomy impacts the onset of Parkinsons disease. However, the mechanisms underlying the aggregation of alpha-synuclein in the vermiform appendix remains poorly understood. To explore this, we assessed aggregation properties in postmortem appendix tissues from healthy controls and synucleinopathy patients using the alpha-synuclein seed amplification assay (alpha-synuclein-SAA) and performed total RNA sequencing alongside differential bisulfite-hybridization-based DNA methylation analysis in the same tissues to investigate the molecular underpinnings. Moreover, we determined alpha-synuclein cleavage patterns by cataloging soluble alpha-synuclein proteoforms from postmortem substantia nigra and post-surgical appendix tissues using top-down mass spectrometry (TD-MS). Alpha-synuclein-SAA was positive in appendix samples for 68.75% of synucleinopathy patients and 6.6% of controls. Genomic profiling revealed dysregulated expression of genes linked to protein folding/degradation, immune/inflammatory responses, and ciliary dynamics in synucleinopathy appendix tissues. TD-MS identified 65 distinct alpha-synuclein proteoforms in the substantia nigra and appendix, with 9 unique to the appendix. Further, in silico modeling revealed higher aggregation propensity of alpha-synuclein proteoforms in the appendix versus substantia nigra. Together, our findings suggest that a tissue environment of alpha-synuclein dysproteostasis in the appendix has the potential to contribute to the development of synucleinopathies. One Sentence SummaryAppendixes from synucleinopathy patients show altered gene expression, unique -syn proteoforms, and higher aggregation propensity than substantia nigra.

neuroscience↗

bioRxiv2024

Identification of novel myokines and putative protein targets that mediate functional adaptations in response to chronic contractile activity induced skeletal muscle-extracellular vesicle treatment

We have previously shown that skeletal muscle-derived extracellular vesicles (EVs) released post-chronic contractile activity (CCA) increased mitochondrial biogenesis in murine myoblasts, and decreased cell viability and induced apoptosis and senescence in non-small cell lung cancer cells. While the underlying mechanisms are unknown, the effects perpetuated were dependent on membrane-bound proteins. Here, we performed an extensive LC-MS/MS proteomic analysis on EVs from control and CCA myotubes. A total of 2900 proteins were identified in CON-EVs and CCA-EVs, including EV-associated proteins such as TSG101, tetraspanins (CD9, CD81, and CD63), flotillin-1, and annexins. Of these, 856 proteins are novel and not listed in EV databases (ExoCarta and Vesiclepedia), indicating that myotube-EVs harbor proteins not yet identified in EVs of different origin. Additionally, we identified 2062 unique proteins that have not yet been previously reported in myotube-EVs to date. Remarkably, of the 2900 total proteins identified, we observed 46 upregulated, and 25 downregulated differentially expressed proteins (DEPs) in CCA-EVs vs. control-EVs. Most of upregulated DEPs include EV-associated proteins. Comparing the 71 DEPs with proteins expressed in skeletal muscle indicated 61 of these as potential myokines. We identified actin cytoskeleton signaling, integrin signaling and muscle contraction as the most enriched pathways among the DEPs using different databases/software including FunRich, KEGG, STRING and Ingenuity Pathway Analysis. Using a relevance score that prioritized membrane-bound proteins with known function in mitochondrial biogenesis and inhibition of cancer growth, we identified top-scoring highly enriched DEPs of interest: IGF1R, ATP7A, PFN1, GJA1, PRKCA and ITGA6. We confirmed upregulation of these targets in EVs using immunoblotting. Among these top-scoring DEPs, PFN1, and ITGA6 are associated with EVs, with expression upregulated following acute exercise. In summary, we report the first comprehensive analysis of skeletal muscle-EV proteome following CCA, with identification of putative protein targets and signaling pathways that may execute the pro-metabolic and anti-tumorigenic effects of CCA-EVs.

cell biology↗