Biology subjects

Dang, L. T.

Publications and source records attributed to Dang, L. T..

7 recordsLinked to original sources

bioRxiv2026

RAI1 safeguards fidelity and tempo of human neurodevelopmental gene expression

Human brain development proceeds on an unusually long timeline relative to other species, a feature that is thought to foster advanced cognitive abilities. The Retinoic Acid Induced 1 (RAI1) gene encodes a nucleosome-binding protein, and its haploinsufficiency is responsible for Smith-Magenis Syndrome (SMS), a neurodevelopmental disorder characterized by cognitive impairment with autistic features. However, the role of RAI1 in human neurodevelopment remains unexplored experimentally. Here, we generated isogenic heterozygous and homozygous RAI1 loss-of-function human embryonic stem cell lines and interrogated the roles of RAI1 in neurodevelopmental gene regulation. A longitudinal transcriptome analysis during in vitro cortical development revealed that RAI1 deficiency accelerates the progression of developmental gene expression. Single-cell RNA-seq analysis revealed that RAI1-deficient neuroprogenitors acquire a transient mesoderm-like gene expression signature, followed by a pro-neuronal maturation signature in postmitotic neurons. Unexpectedly, the developmental acceleration signature was exacerbated during NGN2-induced excitatory neuron differentiation, isolating the roles of RAI1 in neuronal differentiation from non-neuronal functions. Together, these results identify RAI1 as a suppressor of the mesodermal lineage program and as a brake that slows the tempo of human neurodevelopmental gene expression.

neuroscience↗

bioRxiv2026

STRADA Deficiency Impairs Cortical Interneuron Development in Humans and Mice

Polyhydramnios, Megalencephaly, and Symptomatic Epilepsy syndrome (PMSE/STRADA-related disorder) is a rare neurodevelopmental disorder characterized by megalencephaly (ME), early-onset drug-resistant epilepsy, neurocognitive impairment, and high early mortality, often due to status epilepticus. PMSE is caused by a multi-exon deletion in STRADA, encoding STRADA, which regulates the mechanistic target of rapamycin (mTOR) pathway. GABAergic inhibitory interneurons (INs) critically modulate the excitatory:inhibitory balance in cortical and hippocampal networks, and IN deficits contribute to epileptogenesis in several epileptic encephalopathies. However, no studies have investigated INs in PMSE. We used a multimodal approach to study INs in a Strada-/- mouse model engineered with the same causative 5-exon deletion identified in human PMSE. We demonstrate that Strada/STRADA loss causes a reduction of INs in the somatosensory cortex and a corresponding increase in the striatum, representative of remnant ganglionic eminence progenitor origin, in Strada-/- mice and a single PMSE brain tissue specimen. RNA sequencing comparing wildtype to Strada-/- cortex and striatum corroborated these findings, revealing increased IN-related gene expression (e.g., Dlx2) in the striatum and decreased IN-related gene expression (e.g., Pvalb) in the developing cortex. Cytoskeletal (e.g., Tpp3, Kank4, Map1a) and mTOR-associated genes (e.g., Rictor, Cryab) are differentially expressed in the developing cortex, mature striatum, and mature cortex of Strada-/- mice. Functional validation confirmed enlarged INs in mouse and human Strada/STRADA-deficient brain and enhanced S6 phosphorylation in Strada-/- striatum. Together, these findings suggest STRADA/Strada loss contributes to failed IN migration -- the first such report in a developmental, mTOR-associated megalencephaly syndrome -- highlighting INs as a therapeutic target for seizure prevention in PMSE. Key PointsO_LI- Reduced numbers of cortical inhibitory interneurons were observed in the cerebral cortex of Strada-/- mice, with striatal interneuron aggregation C_LIO_LI- Reduced numbers of cortical inhibitory interneurons, with an aggregation in striatum, were observed in human PMSE brain, supporting the observations in Strada-/- mouse C_LIO_LI- Transcriptomic analysis in Strada-/- mice reveals evidence of early developmental interneuron and cytoskeletal dysfunction C_LIO_LI- We introduce a loss of cortical interneurons as a salient feature of PMSE developmental pathogenesis, potentially contributing to a loss of inhibitory modulation C_LIO_LI- This is the first study proposing interneuron migration impairment in the developmental pathogenesis of an mTOR-associated megalencephaly syndrome C_LI

neuroscience↗

bioRxiv2025

KCNQ2 Loss-of-Function variants disrupt neuronal maturation via early hyperexcitability followed by maladaptive network remodeling

Loss-of-function (LOF) variants in the potassium channel subunit KCNQ2 cause a spectrum of neonatal epilepsies from self-limiting familial neonatal epilepsy (SeLFNE) to severe developmental and epileptic encephalopathy (DEE). To dissect the developmental consequences of KCNQ2 LOF, we conducted a longitudinal and multimodal comparative analysis in a human neuronal model generated from patients with KCNQ2-DEE and KCNQ2-SeLFNE. KCNQ2-LOF induced a biphasic network dysfunction, with early Kv7-driven hyperexcitability rescued by acute Retigabine (RTG) treatment, followed by maladaptive remodeling in the opposite direction. Transcriptomic analysis mirrored this biphasic dynamic trajectory, revealing an initial upregulation followed by a subsequent downregulation of synaptic genes. Structural analysis showed a steeper decline in presynaptic density alongside a distal shift in the axon initial segment (AIS) throughout maturation, and impaired AIS plasticity at later stages. Overall, KCNQ2-LOF disrupts human neuronal maturation through dynamic, biphasic changes in function, gene expression and structure, offering insights into disease mechanisms and therapeutic options.

neuroscience↗

bioRxiv2025

Delayed forebrain excitatory and inhibitory neurogenesis inSTRADA-related megalencephaly via mTOR hyperactivity

Biallelic pathogenic variants in STRADA, an upstream regulator of the mechanistic target of rapamycin (mTOR) pathway, result in megalencephaly, drug-resistant epilepsy, and severe intellectual disability. This study explores how mTOR pathway hyperactivity alters cell fate specification in dorsal and ventral forebrain development using STRADA knock-out human stem cell derived brain organoids. In both dorsal and ventral forebrain STRADA knock-out organoids, neurogenesis is delayed, with a predilection for progenitor renewal and proliferation and an increase in outer radial glia. Ventrally, interneuron subtypes shift to an increase in neuropeptide-Y expressing cells. Inhibition of the mTOR pathway with rapamycin results in rescue for most phenotypes. When mTOR pathway variants are present in all cells of the developing brain, overproduction of interneurons and altered interneuron cell fate may underlie mechanisms of megalencephaly, epilepsy, and cognitive impairment. Our findings suggest mTOR inhibition during fetal brain development as a potential therapeutic strategy in STRADA deficiency.

neuroscience↗

bioRxiv2025

Cryopreservation of Human Cortical Organoids Using Vitrification.

Cryopreservation at ultra-low temperatures is a valuable tool for preserving cells and tissues used in research. However, few protocols exist for the preservation of brain organoid models. Current methods for preserving human cortical organoids (hCOs) rely on conventional slow cooling approaches with organoids suspended in a medium containing a cocktail of cryoprotectants. In contrast, we have optimized a vitrification technique previously used to cryopreserve human embryos and oocytes for application to hCOs. We have successfully cryopreserved hCOs that were generated by two different protocols. The vitrified organoids demonstrate a growth rate, cytoarchitecture, cell type composition and electrical activity comparable to non-vitrified controls. Our hCO cryopreservation method provides a useful alternative approach for bio-banking and cross-institutional collaboration using cortical organoids as their model system. Highlights- Human pluripotent stem cell (hPSC) derived hCOs can be cryopreserved using vitrification. - Vitrified hCOs develop similarly to non-vitrified controls. - Vitrified hCOs can be stored long-term and shipped to other institutions. MotivationMany methods of cryopreservation have been developed for the maintenance of cell lines, organoid models and tissues. Most organoid models have been successfully preserved using conventional slow-cooling methods; however, human cortical organoids have been difficult to preserve. Our findings demonstrate that the vitrification of cortical organoids preserves their structure, cell type diversity and function upon rewarming and continued culture.

neuroscience↗

bioRxiv2024

Knock-in Kcnh2 Rabbit Model of Long QT Syndrome Type-2, Epilepsy, and Sudden Death

BackgroundLong QT Syndrome Type-2 (LQT2) is due to loss-of-function KCNH2 variants. KCNH2 encodes Kv11.1 that forms a delayed-rectifier potassium channel in the brain and heart. LQT2 is associated with arrhythmias, seizures, sudden cardiac death, and sudden unexpected death in epilepsy (SUDEP). The goal of the study is to develop a translational model that reproduces the neuro-cardiac electrical abnormalities and sudden death seen in people with LQT2. MethodsWe generated the first knock-in rabbit model of LQT2 (Kcnh2(+/7bp-del)), due to a 7 base-pair (7bp) deletion in the pore domain of the endogenous rabbit Kcnh2 gene. ResultsMutant Kcnh2 is expressed in the heart and brain and constitutes 11% of total Kcnh2 in Kcnh2(+/7bp-del) rabbits. Total Kcnh2, WT Kcnh2, and WT Kv11.1 expression is lower in Kcnh2(+/7bp-del) vs. WT rabbits. Kcnh2(+/7bp-del) rabbits exhibit prolonged cardiac ventricular repolarization (QTc, JTec, JTpc). There is an increased prevalence of spontaneous epileptiform activity and clinical seizures in Kcnh2(+/7bp-del) (7 of 37 rabbits) vs. WT rabbits (1:68 rabbits, p<0.003). 18.9% of Kcnh2(+/7bp-del) vs. 1.5% of WT rabbits died suddenly and spontaneously (p<0.003). We recorded 2 spontaneous lethal events in Kcnh2(+/7bp-del) rabbits: (1) sudden cardiac death and (2) seizure-mediated sudden death due to generalized tonic-clonic seizures, post-ictal generalized EEG suppression, bradycardia, ECG-T-wave inversion, focal cardiac activity, and asystole/death. ConclusionsWe developed the first genetic rabbit model of LQT2 that reproduces the cardiac and epileptic phenotypes seen in people with LQT2. Kcnh2(+/7bp-del) rabbits provide a valuable tool for future mechanistic studies, development of neurotherapeutics, and cardiac-safety testing.

physiology↗

bioRxiv2020

MonaGO: a novel Gene Ontology enrichment analysis visualisation system

MonaGO is a novel web-based visualisation system that provides an intuitive, interactive and responsive interface for performing gene ontology (GO) enrichment analysis and visualising the results. MonaGO combines dynamic clustering and interactive visualisation as well as customisation options to assist biologists in obtaining meaningful representation of overrepresented GO terms, producing simplified outputs in an unbiased manner. MonaGO supports gene lists as well as GO terms as inputs. Visualisation results can be exported as high-resolution images or restored in new sessions, allowing reproducibility of the analysis. An extensive comparison between MonaGO and 11 state-of-the-art GO enrichment visualisation tools based on 9 features revealed that MonaGO is the only platform that simultaneously allows interactive visualisation within one single output page, directly accessible through a web browser with customisable display options. In summary, MonaGO will facilitate the interpretation of GO analysis and will assist the biologists into the representation of the results.

bioinformatics↗