Biology subjects

Nguyen, M. L. T.

Publications and source records attributed to Nguyen, M. L. T..

4 recordsLinked to original sources

bioRxiv2025

LncRNA H19 Upregulation Links Hypoplastic Left Heart Syndrome to Impaired PINK1/Parkin-Mediated Mitophagy and Ischemic Vulnerability

BACKGROUNDThe myocardium in hypoplastic left heart syndrome (HLHS) exhibits immature metabolic programming, impaired mitochondrial quality control, and heightened susceptibility to ischemic and hypoxic injury during palliative surgery. The long non-coding RNA H19 suppresses translation of PTEN-induced putative kinase 1 (PINK1) mRNA and modulates mitochondrial quality control and ischemia/reperfusion injury (IRI) in adult hearts. Whether--and how--H19 regulates mitophagy and IRI in HLHS or in immature animals remains unknown. METHODSWe investigated H19 regulation and its role in mitophagy and ischemia/reperfusion or hypoxia/reoxygenation injury in myocardial tissue from HLHS patients, HLHS-specific induced pluripotent stem cell-derived cardiomyocytes (HLHS-iPSC-CMs), and immature rat hearts. Mechanistic interactions among H19, PINK1/Parkin signaling, and mitophagosome formation were assessed using loss-of-function approaches. RESULTSHLHS myocardium exhibited markedly elevated H19 expression, accompanied by reduced PINK1 and Parkin protein abundance and diminished mitophagosome formation. Similar findings were observed in HLHS-iPSC-CMs exposed to hypoxia/reoxygenation and in immature rat hearts subjected to myocardial IRI. H19 knockdown in HLHS-iPSC-CMs attenuated hypoxia/reoxygenation-induced lactate dehydrogenase release and restored PINK1 and Parkin protein levels. In immature rats, myocardial H19 silencing reduced infarct size, enhanced mitochondrial PINK1 and Parkin expression, and improved post-reperfusion cardiac function for up to 28 days. Conversely, knockdown of PINK1 or Parkin reduced mitophagosome formation and exacerbated functional deterioration during IRI. CONCLUSIONSH19 upregulation impairs PINK1/Parkin-dependent mitophagy and increases susceptibility to ischemic and hypoxic injury in HLHS and the immature heart. These findings identify H19 as a key regulator of mitochondrial quality control and a potential therapeutic target for mitigating IRI in early-life cardiac disease. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/694773v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@193defdorg.highwire.dtl.DTLVardef@114ce7forg.highwire.dtl.DTLVardef@1010d05org.highwire.dtl.DTLVardef@1fdeac1_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO C_FIG Novelty and SignificanceO_ST_ABSWhat Is Known?C_ST_ABSO_LIThe myocardium in hypoplastic left heart syndrome (HLHS) exhibits immature metabolic programming, abnormal coronary perfusion, and impaired mitochondrial quality control, rendering it highly susceptible to ischemic and hypoxic injury. C_LIO_LIBoth structural limitations and intrinsic mitochondrial dysfunction contribute to the reduced ischemic tolerance of the HLHS heart, particularly during surgical and hemodynamic stress. C_LIO_LIThe long noncoding RNA H19 regulates mitochondrial quality control and modulates myocardial ischemia/reperfusion injury (IRI) in adult hearts. C_LIO_LIH19 inhibits the binding of the translation initiation factor eIF4A2 to PTEN-induced putative kinase 1 (PINK1) mRNA, thereby suppressing PINK1 protein synthesis and influencing PINK1-dependent mitophagy in adult mice. C_LI What New Information Does This Article Contribute?O_LIThis study identifies robust upregulation of H19 in HLHS myocardium, HLHS-specific induced pluripotent stem cell-derived cardiomyocytes (HLHS-iPSC-CMs) exposed to hypoxia/reoxygenation, and in immature rats subjected to myocardial IRI. C_LIO_LIElevated H19 is associated with suppressed PINK1/Parkin-dependent mitophagy, exacerbated IRI, and adverse post-injury remodeling. C_LIO_LIKnockdown of H19 restores mitochondrial PINK1 and Parkin protein levels, enhances mitophagy, reduces infarct size, and improves long-term recovery of cardiac function--demonstrating a previously unrecognized pathogenic role for H19 in the immature heart under stress. C_LIO_LIKnockdown of PINK1 or Parkin decreases mitophagosomes and exacerbates myocardial IRI in immature rats. C_LI

genomics↗

bioRxiv2020

KDM6B-dependent chromatin remodelling underpins effective virus-specific CD8+ T cell differentiation.

Naive CD8+ T cell activation results in an autonomous program of cellular proliferation and differentiation. However, the mechanisms that underpin this process are unclear. Here we profiled genome-wide changes in chromatin accessibility, gene transcription and the deposition of a key chromatin modification (H3K27me3) early after naive CD8+ T cell activation. Rapid upregulation of the histone demethylase, KDM6B, prior to first cell division was required for initiating H3K27me3 removal at genes essential for subsequent T cell differentiation and proliferation. Inhibition of KDM6B-dependent H3K27me3 demethylation limited the magnitude of an effective primary virus-specific CD8+ T cell response and the formation of memory CD8+ T cell populations. Accordingly, we define the early spatio-temporal events underpinning early lineage-specific epigenetic reprogramming that is necessary for autonomous CD8+ T cell proliferation and differentiation.

immunology↗

bioRxiv2019

Rapid discovery of synthetic DNA sequences to rewrite endogenous T cell circuits

Genetically-engineered immune cell therapies have been in development for decades1-3 and recently have proven effective to treat some types of cancer4. CRISPR-based genome editing methods, enabling more flexible and targeted sequence integrations than viral transduction, have the potential to extend the clinical utility of cell therapies5,6. Realization of this potential depends on improved knowledge of how coding and non-coding sites throughout the genome can be modified efficiently and on improved methods to discover novel synthetic DNA sequences that can be introduced at targeted sites to enhance critical immune cell functions. Here, we developed improved guidelines for non-viral genome targeting in human T cells and a pooled discovery platform to identify synthetic genome modifications that enhance therapeutically-relevant cell functions. We demonstrated the breadth of targetable genomic loci by performing large knock-ins at 91 different genomic sites in primary human T cells, and established the power of flexible genome targeting by generating cells with Genetically Engineered Endogenous Proteins (GEEPs) that seamlessly integrate synthetic and endogenous genetic elements to alter signaling input, output, or regulatory control of genes encoding key immune receptors. Motivated by success in introducing synthetic circuits into endogenous sites, we then developed a platform to facilitate discovery of novel multi-gene sequences that reprogram both T cell specificity and function. We knocked in barcoded pools of large DNA sequences encoding polycistronic gene programs. High-throughput pooled screening of targeted knock-ins to the endogenous T cell receptor (TCR) locus revealed a transcriptional regulator and novel protein chimeras that combined with a new TCR specificity to enhance T cell responses in the presence of suppressive conditions in vitro and in vivo. Overall, these pre-clinical studies provide flexible tools to discover complex synthetic gene programs that can be written into targeted genome sites to generate more effective therapeutic cells.

immunology↗

bioRxiv2018

Landscape of stimulation-responsive chromatin across diverse human immune cells

The immune system is controlled by a balanced interplay among specialized cell types transitioning between resting and stimulated states. Despite its importance, the regulatory landscape of this system has not yet been fully characterized. To address this gap, we collected ATAC-seq and RNA-seq data under resting and stimulated conditions for 25 immune cell types from peripheral blood of four healthy individuals, and seven cell types from three fetal thymus samples. We found that stimulation caused widespread chromatin remodeling, including a large class of response elements shared between stimulated B and T cells. Furthermore, several autoimmune traits showed significant heritability in stimulation-responsive elements from distinct cell types, highlighting the critical importance of these cell states in autoimmunity. Use of allele-specific read-mapping identified thousands of variants that alter chromatin accessibility in particular conditions. Notably, variants associated with changes in stimulation-specific chromatin accessibility were not enriched for associations with gene expression regulation in whole blood - a tissue commonly used in eQTL studies. Thus, large-scale maps of variants associated with gene regulation lack a condition important for understanding autoimmunity. As a proof-of-principle we identified variant rs6927172, which links stimulated T cell-specific chromatin dysregulation in the TNFAIP3 locus to ulcerative colitis and rheumatoid arthritis. Overall, our results provide a broad resource of chromatin landscape dynamics and highlight the need for large-scale characterization of effects of genetic variation in stimulated cells.

genomics↗