Biology subjects

Tetreault, M.

Publications and source records attributed to Tetreault, M..

7 recordsLinked to original sources

bioRxiv2025

Optimized CRISPR/Cas9 Electroporation and Single Cell Cloning Protocol for Generating Pure Cellular Models in Human Immortalized Myoblasts

BackgroundGenome editing in human skeletal muscle research requires protocols that maximize delivery while preserving viability and clonal outgrowth. We sought to develop a reagent-free workflow for CRISPR/Cas9 editing in human immortalized myoblasts and to demonstrate its performance in two use cases, an IARS1 knockout and an MLIP homozygous knock-in. MethodsWe optimized electroporation parameters using a green fluorescent protein reporter to compare three electrical settings for transfection and survival in E6/E7 myoblasts, then applied ribonucleoprotein delivery for editing. We evaluated the effect of confluency at electroporation, performed single-cell cloning without antibiotics or fluorescence-activated sorting, and validated edits by high-resolution melting pre-screen followed by Sanger sequencing. ResultsElectroporation optimization identified one parameter set that maximized delivery while preserving viability. Performing electroporation at low confluency increased clonal outgrowth and editing rates. The workflow yielded an 84% success rate for IARS1 knockout and a 3.3% success rate for MLIP homozygous knock-in. High-resolution melting provided a very sensitive pre-screen, detecting 96% to 100% of actual edits, reducing the number of Sanger sequencing needed. Performance was reproducible across runs and myoblast lines and increasing single-cell seeding scaled yields without compromising purity. ConclusionsThis work provides a practical and reproducible selection-free protocol that couples electroporation optimization, low confluency editing, single-cell cloning, and high-resolution melting sorting to generate pure edited myoblast lines. The approach is applicable to disease modeling in neuromuscular research and clarifies feasibility boundaries for essential genes and homology-directed repair in these cells.

cell biology↗

bioRxiv2024

Neuronal lipid droplets play a conserved and sex-biased role in maintaining whole-body energy homeostasis

ABSTRACTLipids are essential for neuron development and physiology. Yet, the central hubs that coordinate lipid supply and demand in neurons remain unclear. Here, we combine invertebrate and vertebrate models to establish the presence and functional significance of neuronal lipid droplets (LD) in vivo. We find that LD are normally present in neurons in a non-uniform distribution across the brain, and demonstrate triglyceride metabolism enzymes and lipid droplet-associated proteins control neuronal LD formation through both canonical and recently-discovered pathways. Appropriate LD regulation in neurons has conserved and male-biased effects on whole-body energy homeostasis across flies and mice, specifically neurons that couple environmental cues with energy homeostasis. Mechanistically, LD-derived lipids support neuron function by providing phospholipids to sustain mitochondrial and endoplasmic reticulum homeostasis. Together, our work identifies a conserved role for LD as the organelle that coordinates lipid management in neurons, with implications for our understanding of mechanisms that preserve neuronal lipid homeostasis and function in health and disease. HIGHLIGHTSO_LILipid droplets (LD) normally form in neurons across species Neuronal LD are regulated by a conserved gene network C_LIO_LINeuronal LD regulation plays a conserved and sex-biased role in maintaining energy homeostasis C_LIO_LILD regulation supports ER and mitochondrial function in hunger-activated neurons C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/613929v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@1936e92org.highwire.dtl.DTLVardef@40478aorg.highwire.dtl.DTLVardef@18d5faorg.highwire.dtl.DTLVardef@882ee9_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Ketogenic interventions restore cognition and modulate peripheral metabolic dysfunctions in Alzheimer's disease mouse models

Lifestyle factors modulate dementia risk. We investigated mechanisms of dementia risk reduction by emerging dietary ketogenic interventions. We show that distinct interventions, a medium-chain triglycerides (MCT)-enriched diet and a carbohydrate-free, high-fat diet (CFHF), improve cognition and dendritic spine density of memory-associated hippocampal neurons in two mouse models of Alzheimers disease (AD). Only the CFHF diet drove increased circulating ketones, suggesting distinct underlying mechanisms. AD mice exhibited baseline and diet-induced susceptibility to peripheral metabolic disturbances that were improved by MCT and exacerbated by CFHF diets. Prominent AD-associated dysregulation of the liver transcriptome was largely restored by both interventions, but MCT also downregulated lipogenic enzymes and did not trigger a CFHF-like inflammatory signature. Novel AD- and diet-induced plasmatic changes in hormones and lipid species were identified. Thus, different ketogenic interventions yield cognitive benefits in AD models while showing intervention-specific modulation of peripheral metabolic defects, with implications for design of therapeutic ketogenic strategies.

neuroscience↗

bioRxiv2024

Mapping the peripheral immune landscape of Parkinson's disease patients with single-cell sequencing

Parkinsons Disease (PD) is most recognized for its impact on the central nervous system. However, recent breakthroughs underscore the crucial role of interactions between central and peripheral systems in PDs pathogenesis. The spotlight is now shifting as we explore beyond the central nervous system, discovering that peripheral changes such as inflammatory dysfunctions may predict the rate of disease progression and severity. Despite more than 200 years of research on PD, reliable diagnostic or progression biomarkers and effective disease-modifying treatments are still lacking. Additionally, the cellular mechanisms that drive changes in immunity are largely unknown. Thus, understanding peripheral immune signatures could lead to earlier diagnosis and more effective treatments for PD. Here, we sought to define the transcriptomic alterations of the complete peripheral immune cell compartment by single-cell RNA- and T-cell receptor-sequencing with hopes of uncovering PD signatures and potential peripheral blood biomarkers. Following transcriptional profiling of 78 876 cells from 10 healthy controls and 14 PD donors, we observed five major classes of immune cell types; myeloid (monocytes, dendritic cells) and lymphoid (T, B, natural killer) cells from which we identified 38 cellular subtypes following bioinformatic re-clustering. Comparing immune cell subtypes and phenotypes between PD patients and healthy controls revealed notable features of PD: 1) a significant shift of classical CD14+ monocytes towards an activated CD14+/CD83+ state, 2) changes in lymphocyte subtype abundance, including a significant decrease in CD4+ naive and mucosal-associated invariant T-cells subtypes, along with an increase in CD56+ natural killer cells, 3) the identification by T-cell receptor sequencing of several PD specific T-cell clones shared between multiple patients, suggesting the implication of common epitopes in PD pathogenesis, 4) a notable increase in the expression of activation signature genes, including the AP-1 stress-response transcription factor complex, across all PD cell types. This signal was not present in atypical parkinsonism patients with multiple systems atrophy or progressive supranuclear palsy. Overall, we present a comprehensive atlas of peripheral blood mononuclear cells from control and PD patients which should serve as a tool to improve our understanding of the role the immune cell landscape plays in PD pathogenesis.

genetics↗

bioRxiv2024

RFC1 regulates the expansion of neural progenitors in the developing zebrafish cerebellum

DNA replication and repair are basic yet essential molecular processes for all cells. RFC1 encodes the largest subunit of the Replication Factor C (RFC), which is a clamp-loader during DNA replication and repair. Intronic repeat expansion in RFC1 has recently been associated with so-called RFC1-related disorders, which mainly encompass late-onset cerebellar ataxias. However, the mechanisms that make certain tissues more susceptible to defects in these universal pathways remain mysterious. In this study, we provide the first investigation of RFC1 gene function in vivo using zebrafish. We showed that RFC1 is expressed in neural progenitor cells within the developing cerebellum and that it is necessary to maintain these cells genomic integrity during neurogenic maturation. Accordingly, RFC1 loss-of-function leads to a severe cerebellar phenotype due to impaired neurogenesis of both Purkinje and granule cells. Our data thus point to a specific role of RFC1 in the developing cerebellum, paving the way for a better understanding of the pathogenic mechanisms underlying RFC1-related disorders.

developmental biology↗

bioRxiv2023

Comparative Analysis of Methods to Reduce Activation Signature Gene Expression in PBMCs

Preserving the in vivo cell transcriptome is essential for accurate profiling, yet factors during cell isolation including time ex vivo and temperature induce artifactual gene expression, particularly in stress-responsive immune cells. In this study, we investigated two methods to mitigate ex vivo activation signature gene (ASG) expression in peripheral blood mononuclear cells (PBMCs): transcription and translation inhibitors (TTis) and cold temperatures during isolation. Comparative analysis of PBMCs isolated with TTis revealed reduced ASG expression. However, TTi treatment impaired responsiveness to LPS stimulation in subsequent in vitro experiments. In contrast, cold isolation methods also prevented ASG expression; up to a point where the addition of TTis during cold isolation offered minimal additional advantage. These findings highlight the importance of considering the advantages and drawbacks of different isolation methods to ensure accurate interpretation of PBMC transcriptomic profiles. HighlightsO_LITraditional room temperature isolation methods trigger activation signature gene expression in PBMCs, even when rapidly isolated, whereas 4{degrees}C isolation methods do not. C_LIO_LITranscription and translation inhibitors and cold processing techniques reduce activation signature gene expression via shared mechanisms. C_LIO_LIPBMCs treated with transcription and translation inhibitors lose responsiveness to external stimuli. C_LIO_LICold isolation methods offer a suitable and inexpensive alternative to mitigate activation signature gene expression in PBMCs. C_LI

immunology↗

bioRxiv2020

TDP-43 stabilizes transcripts encoding stress granule protein G3BP1: potential relevance to ALS/FTD

TDP-43 nuclear depletion and concurrent cytoplasmic accumulation in vulnerable neurons is a hallmark feature of progressive neurodegenerative proteinopathies such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Cellular stress signalling and stress granule dynamics are now recognized to play a role in ALS/FTD pathogenesis. Defective stress granule assembly is associated with increased cellular vulnerability and death. G3BP1 (Ras-GAP SH3-domain-binding protein 1) is a critical stress granule assembly factor. Here, we define that TDP-43 stabilizes G3BP1 transcripts via direct binding of a highly conserved cis regulatory element within the 3UTR. Moreover, we show in vitro and in vivo that nuclear TDP-43 depletion is sufficient to reduce G3BP1 protein levels. Finally, we establish that G3BP1 transcripts are reduced in ALS/FTD patient neurons bearing TDP-43 cytoplasmic inclusions/nuclear depletion. Thus, our data suggest that, in ALS/FTD, there is a compromised stress granule response in disease-affected neurons due to impaired G3BP1 mRNA stability caused by TDP-43 nuclear depletion. These data implicate TDP-43 and G3BP1 loss of function as contributors to disease.

neuroscience↗