Global Dysregulation Research Articles

Jag1 represses Notch activation in lateral supporting cells and inhibits an outer hair cell fate in the medial cochlea.

Notch signaling patterns the cochlear organ of Corti, and patients with the JAG1/NOTCH2-related genetic disorder Alagille syndrome can thus experience hearing loss. We investigated the function of Jag1 in cochlear patterning and signaling using Jag1Ndr/Ndr mice, a model of Alagille syndrome. Jag1Ndr/Ndr mice exhibited expected vestibular and auditory deficits, a dose-dependent increase in ectopic inner hair cells, and a reduction in outer hair cells. Single cell RNA sequencing of the organ of Corti demonstrated a global dysregulation of genes associated with inner ear development and deafness. Analysis of individual cell types further revealed that Jag1 represses Notch activation in lateral supporting cells and demonstrated a function for Jag1 in gene regulation and development of outer hair cells. Surprisingly, ectopic "outer hair cell-like" cells were present in the medial compartment and pillar cell region of Jag1Ndr/Ndr cochleae, yet they exhibited location-dependent expression of the inner hair cell fate-determinant Tbx2, suggesting Jag1 is required for Tbx2 to drive inner hair cell commitment. This study thus identifies new roles for Jag1 in supporting cells, and in outer hair cell specification and positioning.

Leveraging explainable deep learning methodologies to elucidate the biological underpinnings of Huntington’s disease using single-cell RNA sequencing data

BackgroundHuntington’s disease (HD) is a hereditary neurological disorder caused by mutations in HTT, leading to neuronal degeneration. Traditionally, HD is associated with the misfolding and aggregation of mutant huntingtin due to an extended polyglutamine domain encoded by an expanded CAG tract. However, recent research has also highlighted the role of global transcriptional dysregulation in HD pathology. However, understanding the intricate relationship between mRNA expression and HD at the cellular level remains challenging. Our study aimed to elucidate the underlying mechanisms of HD pathology using single-cell sequencing data.ResultsWe used single-cell RNA sequencing analysis to determine differential gene expression patterns between healthy and HD cells. HD cells were effectively modeled using a residual neural network (ResNet), which outperformed traditional and convolutional neural networks. Despite the efficacy of our approach, the F1 score for the test set was 96.53%. Using the SHapley Additive exPlanations (SHAP) algorithm, we identified genes influencing HD prediction and revealed their roles in HD pathobiology, such as in the regulation of cellular iron metabolism and mitochondrial function. SHAP analysis also revealed low-abundance genes that were overlooked by traditional differential expression analysis, emphasizing its effectiveness in identifying biologically relevant genes for distinguishing between healthy and HD cells. Overall, the integration of single-cell RNA sequencing data and deep learning models provides valuable insights into HD pathology.ConclusionWe developed the model capable of analyzing HD at single-cell transcriptomic level.

The Cumulative Impact of Recurrent Experiences of Intimate Partner Violence on Emotion Dysregulation: A Longitudinal Investigation.

Intimate partner violence (IPV) disproportionately affects women and has been linked to a range of negative psychological outcomes, including emotion dysregulation. Although IPV is often recurrent and tends to escalate in severity over time, few studies have examined the potential effects of recurrent experiences of IPV on emotion dysregulation. The current study employed a longitudinal design to examine the cumulative impact of recurrent experiences of IPV on emotion dysregulation. Participants were 491 young adult community women (Mage = 21.74; 61.3% White, 35% African American/Black) who completed self-report measures of IPV and emotion dysregulation every 4 months for 28 months. Multilevel structural equation modeling techniques revealed that, at the within-person level, increases in cumulative IPV were associated with increases in global emotion dysregulation across the 28 months. In particular, the accumulation of IPV experiences over time was associated with increases in difficulties controlling impulsive behaviors when distressed and accessing effective emotion regulation strategies. At the between-person level, greater average cumulative IPV was associated with greater mean levels of global emotion dysregulation, as well as four specific dimensions of emotion dysregulation, including difficulties accepting emotional responses, accessing effective emotion regulation strategies, and both engaging in goal-directed behaviors and controlling impulsive behaviors when distressed. These findings suggest the potential cumulative impact of IPV on both global and more specific dimensions of emotion dysregulation. Results also highlight emotion dysregulation as a potentially important construct to assess and target in interventions for women experiencing recurrent IPV.

Maternal Plasma miRNAs as Early Biomarkers of Moderate-to-Late-Preterm Birth.

Globally, preterm birth (PTB) is a primary cause of mortality and morbidity in infants, with PTB rates increasing worldwide over the last two decades. Biomarkers for accurate early prediction of PTB before the clinical event do not currently exist. Given their roles in the development and progression of many disease states, there has been increasing interest in the utility of microRNAs (miRNAs) as early biomarkers for pregnancy-related disorders, including PTB. The present study was designed to examine potential differences in miRNA abundances in maternal plasma from mothers with infants born following a moderate to late (28-36 weeks' gestation, n = 54) spontaneous PTB (SPTB) compared to mothers with matched term infants (n = 54). Maternal plasma collected at 15 weeks' gestation were utilised from the Auckland and Adelaide cohorts from the Screening for Pregnancy Endpoints (SCOPE) study. miRNAs in plasma were quantified using the NanoString nCounter expression panel (800 miRNAs). The top four most abundant miRNAs were significantly decreased in the plasma of mothers in the SPTB group with results consistent across both cohorts and pathway analysis was undertaken to examine the biological processes linked to the dysregulated miRNAs. The top candidate miRNAs (miRs-451a, -223-3p, let-7a-5p, and -126-3p) were linked to gene pathways associated with inflammation, apoptosis, and mitochondrial biogenesis. Moreover, miRNAs were consistently less abundant in the plasma of mothers of preterm infants across both sites, suggesting potential global dysregulation in miRNA biogenesis. This was supported by a significant downregulation in expression of key genes that are involved in miRNA biogenesis (DROSHA, DICER, and AGO2) across both sites in the SPTB group. In summary, the present study has identified miRNAs in maternal plasma that may provide predictive utility as early biomarkers for the risk of later SPTB. Importantly, these observations were conserved across two independent cohorts. Further, our data provide evidence for a persistent decrease in miRNA abundance in mothers who later experienced an SPTB, which is likely to have widespread consequences for gene regulation and epigenetic processes.

CNSC-03. LINKING CELL FATE DETERMINATION IN THE EMBRYONIC FOREBRAIN TO PEDIATRIC HIGH-GRADE GLIOMA

Abstract BACKGROUND Pediatric high-grade gliomas are treatment resistant, usually fatal cancers encompassing diffuse midline glioma, K27-altered (DMG), and diffuse hemispheric glioma, G34R/V (DHG). Most patients harbour canonical and non-canonical mutations in histone variants H3.1 and H3.3, leading to global epigenetic dysregulation and stalled differentiation states as oligodendroglial progenitor cells (OPC) in DMG and GABAergic interneuron precursors in DHG. DLX2 is a homeobox transcription factor that directly represses OPC cell fate and promotes GABAergic interneuron cell fate and migration during early neurogenesis. Methods & Results Our lab has shown DLX2 promoter occupancy of Gad1/Gad2, and early (Olig2, Nkx2.2) and late (Myt1, Plp1) genes required for OPC differentiation in vivo. Co-expression of DLX2 with these target sequences reduces reporter gene expression in vitro, and the Dlx1/Dlx2 double knockout (DKO) mouse showed increases in Olig2, Nkx2.2, and Plp-1 expression in vivo. Transient over-expression of a Dlx2-GFP construct into murine DMG cells resulted in significant increased expression of Gad1/2 isoforms and decreased Olig2 and Nkx2.2, global restoration of H3K27me3 and loss of H3K27 acetylation, as well as a reduction in migration, invasion, and colony formation in vitro. To validate in human pHGG, we first probed an RNA-seq database containing 62 patient-derived pHGG cell lines which demonstrated an inverse correlation between DLX2 expression and OLIG1/2. Cell fate changes in DHG cell lines were evaluated by knockout of DLX2 using CRISPR/Cas9. Concurrently, OLIG1/2-expressing DMG cell lines underwent stable transfection of a DLX2-mCherry overexpression construct in conjunction with a SOX2-BFP overexpression construct, confirmed by qPCR and immunoblot. Analysis of histone H3 marks, K27M, and OPC signature genes will be compared to OPC genes from Dlx1/Dlx2 DKO mouse ganglionic eminences. CONCLUSIONS Manipulation of DLX2 in pHGG provides a model system for assessing the contribution of a homeobox factor to cell fate decisions regulating differentiation and tumorigenicity.

Integrative multi-omic analysis reveals conserved cell-projection deficits in human Down syndrome brains

Down syndrome (DS) is the most common genetic cause of cognitive disability. However, it is largely unclear how triplication of a small gene subset may impinge on diverse aspects of DS brain physiopathology. Here, we took a multi-omic approach and simultaneously analyzed by RNA-seq and proteomics the expression signatures of two diverse regions of human postmortem DS brains. We found that the overexpression of triplicated genes triggered global expression dysregulation, differentially affecting transcripts, miRNAs, and proteins involved in both known and novel biological candidate pathways. Among the latter, we observed an alteration in RNA splicing, specifically modulating the expression of genes involved in cytoskeleton and axonal dynamics in DS brains. Accordingly, we found an alteration in axonal polarization in neurons from DS human iPSCs and mice. Thus, our study provides an integrated multilayer expression database capable of identifying new potential targets to aid in designing future clinical interventions for DS.

Dysregulation of platelet serotonin, 14–3–3, and GPIX in sudden infant death syndrome

Sudden infant death syndrome (SIDS) is the leading cause of post-neonatal infant mortality, but the underlying cause(s) are unclear. A subset of SIDS infants has abnormalities in the neurotransmitter, serotonin (5-hydroxytryptamine [5-HT]) and the adaptor molecule, 14–3–3 pathways in regions of the brain involved in gasping, response to hypoxia, and arousal. To evaluate our hypothesis that SIDS is, at least in part, a multi-organ dysregulation of 5-HT, we examined whether blood platelets, which have 5-HT and 14–3–3 signaling pathways similar to brain neurons, are abnormal in SIDS. We also studied platelet surface glycoprotein IX (GPIX), a cell adhesion receptor which is physically linked to 14–3–3. In infants dying of SIDS compared to infants dying of known causes, we found significantly higher intra-platelet 5-HT and 14–3–3 and lower platelet surface GPIX. Serum and plasma 5-HT were also elevated in SIDS compared to controls. The presence in SIDS of both platelet and brainstem 5-HT and 14–3–3 abnormalities suggests a global dysregulation of these pathways and the potential for platelets to be used as a model system to study 5-HT and 14–3–3 interactions in SIDS. Platelet and serum biomarkers may aid in the forensic determination of SIDS and have the potential to be predictive of SIDS risk in living infants.

Latent profiles of emotion regulation among university students: links to repetitive negative thinking, internet addiction, and subjective wellbeing.

Recent years have seen a deterioration in the mental health of university students and notable surge in the need for psychological support. Due to its links to psychopathology and high-risk behaviors, difficulty in emotion regulation frequently serves as a transdiagnostic dimension. This cross-sectional study used a person-centered analytical approach (latent profile analysis; LPA) to identify groups of Portuguese university students with similar profiles of emotion regulation difficulties (N = 261; Mage = 22.5 ± 1.2 years; n = 213 female) and describe how these groups differ in their presentation of repetitive negative thinking, internet addiction, and subjective wellbeing. The analyses identified four latent profiles: 14.5% of students showed global dysregulation (the Low Emotion Regulation Profile), 23% were moderately dysregulated with elevated problems in goal-directed behavior (the Moderate Emotion Regulation Profile), 8% showed specific difficulties with low emotional awareness and clarity (the Low Insight Profile), and 54.4% showed adaptive emotion regulation (the High Emotion Regulation Profile). As anticipated, the Low Emotion Regulation Profile had the lowest subjective wellbeing and the highest prevalence of repetitive negative thinking and internet addiction. Students with a Low Insight Profile also showed low subjective wellbeing, but less repetitive negative thinking compared to the Low Emotion Regulation Profile. Our findings suggest that interventions aimed at improving health and wellbeing among university students should consider each student's unique set of emotion regulation difficulties, rather than focusing on particular strategies. Further research may help determine whether emotion regulation profiles can serve as predictive indicators of varying mental health trajectories and subjective wellbeing in university students.

Metabolomic changes following GenX and PFBS exposure in developing zebrafish

Short chain per- and polyfluoroalkyl substances (PFAS), including hexafluoropropylene oxide dimer acid (GenX) and perfluorobutane sulfonate (PFBS), are replacement chemicals for environmentally persistent, long-chain PFAS. Although GenX and PFBS have been detected in surface and ground water worldwide, few studies provide information on the metabolic alterations or risks associated with their exposures. In this study, larval zebrafish were used to investigate the toxicity of early-life exposure to GenX or PFBS. Zebrafish were chronically exposed from 4 h post-fertilization (hpf) to 6 days post-fertilization (dpf) to 150 µM GenX or 95.0 µM PFBS. Ultra-high-performance liquid chromatography paired with high-resolution mass spectrometry was used to quantify uptake of GenX and PFBS into zebrafish larvae and perform targeted and untargeted metabolomics. Our results indicate that PFBS was 20.4 % more readily absorbed into the zebrafish larvae compared to GenX. Additionally, PFBS exposure significantly altered 13 targeted metabolites and 21 metabolic pathways, while GenX exposure significantly altered 1 targeted metabolite and 17 metabolic pathways. Exposure to GenX, and to an even greater extent PFBS, resulted in a number of altered metabolic pathways in the amino acid metabolism, with other significant alterations in the carbohydrate, lipid, cofactors and vitamins, nucleotide, and xenobiotics metabolisms. Our results indicate that GenX and PFBS impact the zebrafish metabolome, with implications of global metabolic dysregulation, particularly in metabolic pathways relating to growth and development.

Abstract 1708: Transposable element derived enhancers in ovarian cancer

Abstract There is global epigenetic dysregulation during transformation from normal to cancerous cells. One of the many consequences of this global epigenetic dysregulation is the reactivation of transposable elements (TEs). TEs compose roughly half of the human genome and are normally repressed through epigenetic mechanisms such as DNA methylation and histone modifications. Endogenous retroviruses (ERVs) are a class of TEs that contain long terminal repeats (LTRs) with putative gene regulatory motifs. LTRs can be co-opted to be pro-tumorigenic by becoming non-canonical promotors for oncogenic genes. While several examples of TE-derived promotors have been reported in cancer, the potential significance of TE-derived enhancers remains largely unexplored. Here, we utilized publicly available multi-omics datasets (bulk and single-cell ATAC-seq, bulk and single-cell RNA-seq, and chromatin profiling) in the context of ovarian cancer to determine if there are tumor specific, TE-derived-enhancers that have gene regulatory function. We used CRISPRi technology to functionally validate a putative TE-derived enhancer and gene regulatory axis. We discovered that on the bulk tissue level, several TE families are enriched at open chromatin sites and sites marked by H3K27Ac (enhancer mark) of ovarian tumors, suggesting the presence of tumor specific, TE-derived enhancers. On the single-cell level, we discovered that ovarian cells have the highest expression of these TE transcripts compared to stromal and immune cells in the tumor microenvironment, suggesting that the increased TE-derived enhancer activity observed on the bulk level are specific to ovarian cells. Lastly, when we silenced a specific LTR18 locus upstream of a gene, TIPARP, TIPARP gene expression was also repressed, suggesting that these putative TE-derived enhancers have gene regulatory function. Determining the regulatory role of these TE-derived enhancers will provide novel insights into cancer-related transcriptomes. Citation Format: Lily L. Nguyen, Atma Ivancevic, Benjamin G. Bitler, Edward B. Chuong. Transposable element derived enhancers in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1708.

Induced pluripotent stem cell-derived hepatocytes reveal TCA cycle disruption and the potential basis for triheptanoin treatment for malate dehydrogenase 2 deficiency

Mitochondrial malate dehydrogenase 2 (MDH2) is crucial to cellular energy generation through direct participation in the tricarboxylic acid (TCA) cycle and the malate aspartate shuttle (MAS). Inherited MDH2 deficiency is an ultra-rare metabolic disease caused by bi-allelic pathogenic variants in the MDH2 gene, resulting in early-onset encephalopathy, psychomotor delay, muscular hypotonia and frequent seizures. Currently, there is no cure for this devastating disease. We recently reported symptomatic improvement of a three-year-old girl with MDH2 deficiency following treatment with the triglyceride triheptanoin. Here, we aimed to better characterize this disease and improve our understanding of the potential utility of triheptanoin treatment. Using fibroblasts derived from this patient, we generated induced pluripotent stem cells (hiPSCs) and differentiated them into hepatocytes (hiPSC-Heps). Characterization of patient-derived hiPSCs and hiPSC-Heps revealed significantly reduced MDH2 protein expression. Untargeted proteotyping of hiPSC-Heps revealed global dysregulation of mitochondrial proteins, including upregulation of TCA cycle and fatty acid oxidation enzymes. Metabolomic profiling confirmed TCA cycle and MAS dysregulation, and demonstrated normalization of malate, fumarate and aspartate following treatment with the triheptanoin components glycerol and heptanoate. Taken together, our results provide the first patient-derived hiPSC-Hep-based model of MDH2 deficiency, confirm altered TCA cycle function, and provide further evidence for the implementation of triheptanoin therapy for this ultra-rare disease. SynopsisThis study reveals altered expression of mitochondrial pathways including the tricarboxylic acid cycle and changes in metabolite profiles in malate dehydrogenase 2 deficiency and provides the molecular basis for triheptanoin treatment in this ultra-rare disease.

Multiplexed screening reveals how cancer-specific alternative polyadenylation shapes tumor growth in vivo

Alternative polyadenylation (APA) is strikingly dysregulated in many cancers. Although global APA dysregulation is frequently associated with poor prognosis, the importance of most individual APA events is controversial simply because few have been functionally studied. Here, we address this gap by developing a CRISPR-Cas9-based screen to manipulate endogenous polyadenylation and systematically quantify how APA events contribute to tumor growth in vivo. Our screen reveals individual APA events that control mouse melanoma growth in an immunocompetent host, with concordant associations in clinical human cancer. For example, forced Atg7 3′ UTR lengthening in mouse melanoma suppresses ATG7 protein levels, slows tumor growth, and improves host survival; similarly, in clinical human melanoma, a long ATG7 3′ UTR is associated with significantly prolonged patient survival. Overall, our study provides an easily adaptable means to functionally dissect APA in physiological systems and directly quantifies the contributions of recurrent APA events to tumorigenic phenotypes.

P074 Inflammatory Environment-Induced Transcriptomic Alterations in Crohn's Disease Adipose Stem Cells

Abstract Background Crohn’s disease (CD) is characterised by expansion of mesenteric adipose tissue, called creeping fat, which seems to be directly related to disease activity. Adipose stem cells (ASCs) isolated from the creeping fat of CD patients exhibit dysfunction, featuring impaired adipogenesis and an intensely pro-inflammatory phenotype. This study aims to explore the transcriptome of ASCs isolated from active and inactive CD subjects in comparison with healthy subjects, seeking key markers of this dysregulation. Methods Patients were recruited at Hospital Joan XXIII of Tarragona and Hospital Vall d’Hebron of Barcelona in accordance with the principles of the Helsinki Declaration. Transcriptome profiling was performed in ASCs isolated from adipose-tissue biopsies of visceral origin: CF and hMES in Crohn subjects (n=7, each) and hMES in inactive CD patients (n=7) and healthy control subjects (n=7). Groups were matched by age, gender, and BMI. Finally, we examined the pathways involving the differentially expressed gene (DEGs) in ASCs isolated from patients with CD with different clinical activity by gene set enrichment analysis (GSEA). Results Patients with CD across different clinical activity stages exhibited similar transcriptome patterns, indicating persistent ASC dysregulation even during remission state (Fig 1A). ASCs isolated from both creeping fat and mesenteric adipose tissue distant from intestinal damage displayed similar dysregulation, implying a global dysregulation of all mesenteric fat in CD. Specifically, transcriptomic analysis identified significant dysregulation of the NK2 Homeobox 3 (NKX2-3) gene in ASCs from active CD patients. Although higher NKX2-3 expression has been associated with B cells and intestinal tissues in CD1-3, our study is the first to link elevated expression of this gene also to creeping fat. Pathway enrichment analysis revealed significant enrichment in oxidative stress and immune response pathways in active CD (Fig 1B). Furthermore, our findings indicated also an elevated NKX2-3 expression in ASCs of inactive CD compared to controls, with oxidative stress pathway up-regulation (Fig 1C). Notably, no significant DEGs were found between ASCs from active and inactive CD groups (Fig 1D), suggesting a similar profile in both states. Conclusion Our study reveals profound ASC dysregulation in CD, in both active and inactive phases. Elevated NKX2-3 expression, previously associated with increased risk of complications in IBD, is now demonstrated in the mesenteric adipose tissue, persisting even in inactive CD patients. Ref: 1. Yamazaki K, et al Gut. 2009 Feb;58(2):228-32. 2. Yu W, et al. J Crohn’s Colitis. 2009 Sep;3(3):189-95. 3. Hong SN et al. Gut. 2016 May;65(5):788-96.

Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs

BackgroundA 45,X monosomy (Turner syndrome, TS) is the only chromosome haploinsufficiency compatible with life. Nevertheless, the surviving TS patients still suffer from increased morbidity and mortality, with around one-third of them subjecting to heart abnormalities. How loss of one X chromosome drive these conditions remains largely unknown.MethodsHere, we have generated cardiomyocytes (CMs) from wild-type and TS patient-specific induced pluripotent stem cells and profiled the mRNA, lncRNA and circRNA expression in these cells.ResultsWe observed lower beating frequencies and higher mitochondrial DNA copies per nucleus in TS-CMs. Moreover, we have identified a global transcriptome dysregulation of both coding and non-coding RNAs in TS-CMs. The differentially expressed mRNAs were enriched of heart development genes. Further competing endogenous RNA network analysis revealed putative regulatory circuit of autosomal genes relevant with mitochondrial respiratory chain and heart development, such as COQ10A, RARB and WNT2, mediated by X-inactivation escaping lnc/circRNAs, such as lnc-KDM5C-4:1, hsa_circ_0090421 and hsa_circ_0090392. The aberrant expressions of these genes in TS-CMs were verified by qPCR. Further knockdown of lnc-KDM5C-4:1 in wild-type CMs exhibited significantly reduced beating frequencies.ConclusionsOur study has revealed a genomewide ripple effect of X chromosome halpoinsufficiency at post-transcriptional level and provided insights into the molecular mechanisms underlying heart abnormalities in TS patients.

High-dimensional mass cytometry reveals systemic and local immune signatures in necrotizing enterocolitis.

Patients with necrotizing enterocolitis display severe gastrointestinal complications of prematurity, but the mechanism driving this clinical profile remains unknown. We used mass cytometry time-of-flight to characterize and compare immune cell populations in the blood and intestine tissue from patients with and without (controls) necrotizing enterocolitis at single-cell resolution. We completed a deep mapping of the immune system of the peripheral blood mononuclear cells and intestinal mucosa tissue using mass cytometry to evaluate immune cell types, which revealed global immune dysregulation characteristics underlying necrotizing enterocolitis. Compared with controls, natural killer cells display signs of heightened activation and increased cytotoxic potential in the peripheral blood and mucosa of patients with necrotizing enterocolitis. Furthermore, CD4+ T effector memory cells, non-classical monocytes, active dendritic cells, and neutrophils were specifically enriched in the mucosa, suggesting trafficking from the periphery to areas of inflammation. Moreover, we mapped the systemic and local distinct immune signatures suggesting patterns of cell localization in necrotizing enterocolitis. We used mass cytometry time-of-flight technology to identify immune cell populations specific to the peripheral blood and intestinal mucosa tissue from patients with necrotizing enterocolitis and controls. This information might be used to develop precise diagnosis and therapies that target specific cell populations in patients with necrotizing enterocolitis.

MODL-12. REGULATION OF OLIGODENDROGLIAL PROGENITOR CELL (OPC) CELL FATE IN DIFFUSE MIDLINE GLIOMA (DMG) BY THE HOMEOBOX TRANSCRIPTION FACTOR DLX2

Abstract Diffuse midline glioma, K27-altered (DMG) is a treatment resistant, uniformly fatal cancer that arises predominantly in children. 80% of patients with DMG harbor K27M mutations in canonical histone variants H3.3 and H3.1, leading to global epigenetic dysregulation and an oligodendroglial progenitor cell (OPC) transcriptional profile. DLX2 is a homeobox transcription factor that directly represses OPC cell fate and promotes a GABAergic interneuron cell fate during neurogenesis. Our lab has previously identified DLX2 transcription factor occupancy of genes required for OPC differentiation in vivo (Olig2, Nkx2.2, Myt1, Plp1), and shown that co-expression of DLX2 to target sequences reduced reporter gene expression in vitro. Likewise, increased expression of Olig2, Nkx2.2, and Plp-1 are observed in a Dlx1/Dlx2 double knockout (DKO) mouse model. Transient overexpression of a Dlx2-GFP construct into cells of a genetically engineered mouse model (GEMM) of DMG resulted in increased expression of Gad1/2 isoforms and decreased Olig2 and Nkx2.2, global restoration of H3K27me3, and a reduction in migration, invasion, and colony formation in vitro. Inverse expression of DLX2 and OLIG1/2 was observed in a bulk RNAseq database of 45 human DMG cell lines. We have established a pipeline to evaluate cell fate changes following changes in DLX2 expression levels. OLIG1/2high/DLX2low DMG expressing cell lines underwent stable transfection of a DLX2-mCherry overexpression construct. Successful alteration of DLX2 expression was confirmed by qPCR and immunoblot in knockout and overexpressing human DMG cell lines. Analysis of histone marks (H3K27me3, H3K27ac), K27M, and OPC signature genes will be presented with comparison of altered OPC genes from the DKO mouse as determined by RNA-seq. The manipulation of DLX2 expression in human DMG cells in vitro and in vivo provides a model system for assessing the contribution of a homeobox transcription factor required for neurogenesis to cell fate regulation and effects on tumorigenicity in DMG.

EPCO-41. MICRORNA-MEDIATED DIRECT NEURONAL REPROGRAMMING OF GLIOBLASTOMAS

Abstract Neuron-specific microRNAs miR-9/9* and miR-124 (miR-9/9*-124) are potent neurogenic molecules whose ectopic expression in non-neuronal somatic cells effectively induces direct cell fate conversion into a neuronal fate. Our recent work indicates that the fate transition occurs in distinct steps where miR-9/9*-124 first represses core gene regulatory networks to erase the original non-neuronal cell identity and subsequently activates the neuronal program to confer neuronal fate. Extending these findings, we reason that repression of similar gene regulatory networks by miR-9/9*-124 can also induce fate erasure in cancerous cells using glioblastoma as a paradigm. Glioblastoma multiforme (GBM) is a type of aggressive brain tumor with poor prognosis. Instead of having specific mutation profiles, GBMs present a global genetic network dysregulation which gives rise to a neural stem cell or progenitor cell-like state resembling embryonic neural development. Whereas miR-9/9*-124 plays a key role in inducing mitotic exit and orchestrating neurogenesis during development and neuronal reprogramming, we hypothesize that miR-9/9*-124 will instruct neuronal reprogramming of GBMs. Our results so far demonstrate that miR-9/9*-124 indeed exerts reprogramming activities in patient-derived GBM cell lines. Ectopic expression of miR-9/9*-124 in vitro readily induces GBM cells to exit cell cycle and promotes neuronal identity over time. In GBM intracerebral xenograft mouse model, mice receiving GBM cells overexpressing miR-9/9*-124 were able to survive longer than those with GBMs overexpressing non-specific microRNAs. We are currently carrying out transcriptomic and chromatin accessibility analyses to infer the epigenetic switch as GBM cells are reprogrammed to neurons. Based on these studies, we will further examine whether the GBM cells undergo irreversible fate erasure and are reprogrammed into a stable post-mitotic neuronal state. Our studies will provide insights into the plasticity of GBM fate that can be controlled by microRNAs and the key downstream regulatory nodes underlying fate transition of GBM to permanent post-mitotic state.

CNSC-17. WHOLE-BRAIN SPECTRAL CHANGE IN GLIOBLASTOMA PATIENTS: ASSOCIATIONS WITH CLINICAL COMORBIDITIES AND OVERALL SURVIVAL

Abstract Glioblastoma, a highly aggressive form of brain tumor, is a brain-wide disease. We evaluated the impact of tumor burden on whole brain resting-state functional magnetic resonance imaging (rs-fMRI) activity. Specifically, we analyzed rs-fMRI signals in the temporal frequency domain in terms of the power-law exponent and fractional amplitude of low-frequency fluctuations (fALFF). We contrasted 189 patients with newly-diagnosed glioblastoma versus 189 age-matched reference participants. The patient and reference datasets were matched for age and head motion. The principal finding was markedly flatter spectra and reduced grey matter fALFF in the patients as compared to the reference dataset. We posit that the whole-brain spectral change is attributable to global dysregulation of excitatory and inhibitory balance and metabolic demand in the tumor-bearing brain. Additionally, we observed that clinical comorbidities, in particular, seizures, and MGMT promoter methylation, were associated with flatter spectra. Notably, the degree of change in spectra was predictive of overall survival. Our findings suggest that frequency domain analysis of rs-fMRI activity provides prognostic information in glioblastoma patients and offers a means of noninvasively studying the effects of glioblastoma on the whole brain.

Pathological personality explains individual differences in global emotion dysregulation within the pathway between child maltreatment and severe depressive symptoms.

Global emotion dysregulation mediates the relationship between child maltreatment and severe depressive symptoms; however, there is a lack of research on maladaptive personality traits and their contribution to individual differences in global emotion dysregulation within this conceptual model. The present study tested a preliminary serial mediation model where maladaptive personality traits and global emotion dysregulation mediate the relationship between child maltreatment and severe depressive symptoms. A total of 200 patients with mood disorders (Mage = 36.5 years; 54% females) were assessed for maladaptive personality traits (Personality Inventory for Diagnostic and Statistical Manual of Mental Disorders [5th ed.] Brief Form), global emotion dysregulation (Difficulties in Emotion Regulation Scale-Short), childhood trauma (Childhood Trauma Questionnaire), and depressive symptoms (Patient Health Questionnaire-9). Ordinary least squares regression and partial least squares-structural equation modeling revealed a consistent and significant indirect effect of child maltreatment on severe depressive symptoms through negative affectivity, detachment, psychoticism, and global emotion dysregulation. Among child maltreatment types, only emotional abuse had a significant indirect effect on severe depressive symptoms through maladaptive personality traits and global emotion dysregulation, b = 0.50, SE = 0.09, 95% confidence intervals [0.326, 0.694] after controlling for age, gender, and remaining types of child maltreatment. Findings support the view that maladaptive personality traits shed important insights on individual differences in global emotion dysregulation, and this information could aid clinical formulation and treatment of childhood adversity-related psychopathology. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Supplemental Material for Pathological Personality Explains Individual Differences in Global Emotion Dysregulation Within the Pathway Between Child Maltreatment and Severe Depressive Symptoms

Supplemental Material for Pathological Personality Explains Individual Differences in Global Emotion Dysregulation Within the Pathway Between Child Maltreatment and Severe Depressive Symptoms