Biology subjects

Chen, A.

Publications and source records attributed to Chen, A..

At least 163 records · Page 9Linked to original sources

bioRxiv2023

SAW: An efficient and accurate data analysis workflow for Stereo-seq spatial transcriptomics

The basic analysis steps of spatial transcriptomics involve obtaining gene expression information from both space and cells. This process requires a set of tools to be completed, and existing tools face performance issues when dealing with large data sets. These issues include computationally intensive spatial localization, RNA genome alignment, and excessive memory usage in large chip scenarios. These problems affect the applicability and efficiency of the process. To address these issues, a high-performance and accurate spatial transcriptomics data analysis workflow called Stereo-Seq Analysis Workflow (SAW) has been developed for the Stereo-Seq technology developed by BGI. This workflow includes mRNA spatial position reconstruction, genome alignment, gene expression matrix generation and clustering, and generate results files in a universal format for subsequent personalized analysis. The excutation time for the entire analysis process is [~]148 minutes on 1G reads 1*1 cm chip test data, 1.8 times faster than unoptimized workflow.

bioinformatics↗

bioRxiv2023

An Unsupervised Contrastive Learning Model for Data Integration of Spatially Resolved Transcriptomics

Integrative analysis of spatially resolved transcriptomics datasets empowers a deeper understanding of complex biological systems. However, integrating multiple tissue sections presents challenges for batch effect removal, particularly when the sections are measured by various technologies or collected at different times. Here, we propose spatiAlign, an unsupervised contrastive learning model that employs the expression of all measured genes and the spatial location of cells, to integrate multiple tissue sections. It enables the joint downstream analysis of multiple datasets not only in low-dimensional embeddings but also in the reconstructed full expression space. In benchmarking analysis, spatiAlign outperforms state-of-the-art methods in learning joint and discriminative representations for tissue sections, each potentially characterized by complex batch effects or distinct biological characteristics. Furthermore, we demonstrate the benefits of spatiAlign for the integrative analysis of time-series brain sections, including spatial clustering, differential expression analysis, and particularly trajectory inference that requires a corrected gene expression matrix.

bioinformatics↗

bioRxiv2023

Functional Connectivity Development along the Sensorimotor-Association Axis Enhances the Cortical Hierarchy

Human cortical maturation has been posited to be organized along the sensorimotor-association (S-A) axis, a hierarchical axis of brain organization that spans from unimodal sensorimotor cortices to transmodal association cortices. Here, we investigate the hypothesis that the development of functional connectivity during childhood through adolescence conforms to the cortical hierarchy defined by the S-A axis. We tested this pre-registered hypothesis in four large-scale, independent datasets (total n = 3,355; ages 5-23 years): the Philadelphia Neurodevelopmental Cohort (n = 1,207), Nathan Kline Institute-Rockland Sample (n = 397), Human Connectome Project: Development (n = 625), and Healthy Brain Network (n = 1,126). In each dataset, the development of functional connectivity systematically varied along the S-A axis. Connectivity in sensorimotor regions increased, whereas connectivity in association cortices declined, refining and reinforcing the cortical hierarchy. These robust and generalizable results establish that the sensorimotor-association axis of cortical organization encodes the dominant pattern of functional connectivity development.

neuroscience↗

bioRxiv2023

Evolving Membrane-Associated Accessory Protein Variants for Improved Adeno-Associated Virus Production

Manufacturing sufficient Adeno-Associated Virus (AAV) to meet current and projected clinical needs is a significant hurdle to the growing gene therapy industry. The recently discovered membrane-associated accessory protein (MAAP) is encoded by an alternative open reading frame in the AAV cap gene that is found in all presently reported natural serotypes. Recent evidence has emerged supporting a functional role of MAAP in AAV egress, though the underlying mechanisms of MAAP function remain unknown. Here, we show that inactivation of MAAP from AAV2 by a single point mutation that is silent in the VP1 ORF (AAV2-{Delta}MAAP) decreased exosome-associated and secreted vector genome production. We hypothesized that novel MAAP variants could be evolved to increase AAV production and thus subjected a library encoding over 1E6 MAAP protein variants to five rounds of packaging selection into the AAV2-{Delta}MAAP capsid. Between each successive packaging round, we observed a progressive increase in both overall titer and ratio of secreted vector genomes conferred by the bulk selected MAAP library population. Next-generation sequencing uncovered enriched mutational features, and a resulting selected MAAP variant containing missense mutations and a novel C-terminal domain increased overall GFP transgene packaging in AAV2, AAV6, and AAV9 capsids.

bioengineering↗

bioRxiv2023

The NAD+ Precursor Nicotinamide Riboside Rescues Mitochondrial Defects and Neuronal Loss in iPSC derived Cortical Organoid of Alpers' Disease

Alpers syndrome is an early-onset neurodegenerative disorder usually caused by biallelic pathogenic variants in the gene encoding the catalytic subunit of polymerase-gamma (POLG), which is essential for mitochondrial DNA (mtDNA) replication. The disease is progressive, incurable, and inevitably it leads to death from drug-resistant status epilepticus. The neurological features of Alpers syndrome are intractable epilepsy and developmental regression, with no effective treatment; the underlying mechanisms are still elusive, partially due to lack of good experimental models. Here, we generated the patient-derived induced pluripotent stem cells from one Alpers patient carrying the compound heterozygous mutations of A467T (c.1399G>A) and P589L (c.1766C>T), and further differentiated them into cortical organoids and neural stem cells (NSCs) for mechanistic studies of neural dysfunction in Alpers syndrome. Patient cortical organoids exhibited a phenotype that faithfully replicated the molecular changes found in patient postmortem brain tissue, as evidenced by cortical neuronal loss and depletion of mtDNA and complex I (CI). Patient NSCs showed mitochondrial dysfunction leading to ROS overproduction and downregulation of the NADH pathway. More importantly, the NAD+ precursor nicotinamide riboside (NR) significantly ameliorated mitochondrial defects in patient brain organoids. Our findings demonstrate that the iPSC model and brain organoids are good in vitro models of Alpers disease; this first-in-its-kind stem cell platform for Alpers syndrome enables therapeutic exploration and has identified NR as a viable drug candidate for Alpers disease and, potentially, other mitochondrial diseases with similar causes.

neuroscience↗

bioRxiv2023

Small RNAs from fungal pathogen Botrytis cinerea ride in extracellular vesicles to enter plant cells through clathrin-mediated endocytosis

Small RNAs (sRNAs) of the fungal pathogen Botrytis cinerea can enter plant cells and hijack host Argonaute protein 1 (AGO1) to silence host immunity genes. However, the mechanism by which these fungal sRNAs are secreted and enter host cells remains unclear. Here, we demonstrate that B. cinerea utilizes extracellular vesicles (EVs) to secrete Bc-sRNAs, which are then internalized by plant cells through clathrin-mediated endocytosis (CME). The B. cinerea tetraspanin protein, Punchless 1 (BcPLS1), serves as an EV biomarker and plays an essential role in fungal pathogenicity. We observe numerous Arabidopsis clathrin-coated vesicles (CCVs) around B. cinerea infection sites and the colocalization of B. cinerea EV marker BcPLS1 and Arabidopsis CLATHRIN LIGHT CHAIN 1, one of the core components of CCV. Meanwhile, BcPLS1 and the B. cinerea-secreted sRNAs are detected in purified CCVs after infection. Arabidopsis knockout mutants and inducible dominant-negative mutants of key components of CME pathway exhibit increased resistance to B. cinerea infection. Furthermore, Bc-sRNA loading into Arabidopsis AGO1 and host target gene suppression are attenuated in those CME mutants. Together, our results demonstrate that fungi secrete sRNAs via EVs, which then enter host plant cells mainly through CME.

plant biology↗

bioRxiv2023

Taphonomic damage obfuscates interpretation of the retroarticular region of the Asteriornis mandible

Asteriornis maastrichtensis, from the latest Cretaceous of Belgium, is among the oldest known crown bird fossils, and its three-dimensionally preserved skull provides the most substantial insights into the cranial morphology of early crown birds to date. Phylogenetic analyses recovered Asteriornis as a total-group member of Galloanserae (the clade uniting Galliformes and Anseriformes. One important feature supporting this placement was enlargement of the retroarticular processes, which form elongate caudal extensions of the mandible in extant Galloanserae. Here, we reinterpret the jaw of Asteriornis and illustrate that the caudalmost portion of the mandibles are in fact not preserved. Instead, the caudal extremities of both the left and right mandibular rami extend to the surface of the fossil block containing the holotype skull, where they have eroded away. The originally identified retroarticular process of the right mandible--which exhibits a morphology and orientation strikingly similar to the retroarticular processes of certain extant and fossil galloanserans, including the early Palaeogene total-clade anseriforms Conflicto and Nettapterornis--instead represents a twisted and caudally displaced medial process. Nonetheless, anatomical comparisons with extant taxa reveal that we are unable to exclude the possibility that Asteriornis exhibited robust retroarticular processes comparable to those of extant Galloanserae. In light of the reinterpreted morphology of the Asteriornis mandible, we update the original anatomical character matrix used to investigate its phylogenetic relationships, and our revised phylogenetic analyses continue to support its position as a total-group galloanseran, as initially interpreted. We demonstrate additional morphological traits of the mandible supporting this phylogenetic position and provide new data on the nature and distribution of retroarticular processes among early crown birds.

paleontology↗

bioRxiv2023

Integrated analysis of spatial multi-omics with SpatialGlue

Integration of multiple data modalities in a spatially informed manner remains an unmet need for exploiting spatial multi-omics data. We introduce SpatialGlue, a graph neural network with dual-attention mechanism, to learn each modalitys significance at cross-omics and intra-omics integration. We demonstrate that SpatialGlue can accurately aggregate cell types into spatial domains at a higher resolution on different tissue types and technology platforms, as well as gain insights into cross-modality spatial correlations.

bioinformatics↗

bioRxiv2023

Integrated Spatial Transcriptomic and Proteomic Analysis of Fresh Frozen Tissue Based on Stereo-seq

To simultaneously detect whole transcriptomes and protein markers on the same tissue section, we combined Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq) and Stereo-seq to develop the Stereo-CITE-seq workflow. Here, we demonstrated that Stereo-CITE-seq can co-detect mRNAs and proteins in immune organs with high spatial resolution, reproducibility and accuracy.

molecular biology↗

bioRxiv2023

Defining the mechanisms of action and resistance to the anti-PD-1+LAG-3 and anti-PD-1+CTLA-4 combinations in melanoma flank and brain models

BackgroundAlthough the anti-PD-1+LAG-3 and the anti-PD-1+CTLA-4 combinations are effective in advanced melanoma it remains unclear whether their mechanisms of action and resistance overlap. MethodsWe used single cell (sc) RNA-seq, flow cytometry and IHC analysis of responding SM1 and B16 melanoma flank tumors and SM1 brain metastases to explore the mechanism of action of the anti-PD-1+LAG-3 and the anti-PD-1+CTLA-4 combination. CD4+ and CD8+ T cell depletion and ELISPOT assays were used to demonstrate the unique role of CD4+ T cell help in the anti-tumor effects of the anti-PD-1+LAG-3 combination. Tetramer assays confirmed the loss of CD8+ tumor-reactive T cells in brain tumors resistant to the anti-PD-1+LAG-3 combination. ResultsThe anti-PD-1+CTLA-4 combination was associated with the infiltration of FOXP3+ regulatory CD4+ cells (Tregs), fewer activated CD4+ T cells and the accumulation of a subset of IFN{gamma} secreting cytotoxic CD8+ T cells, whereas the anti-PD-1+LAG-3 combination led to the accumulation of CD4+ T helper cells that expressed CXCR4, TNFSF8, IL21R and a subset of CD8+ T cells with reduced expression of cytotoxic markers. T cell depletion studies showed a requirement for CD4+ T cells for the anti-PD-1+LAG-3 combination, but not the PD-1-CTLA-4 combination at both flank and brain tumor sites. In anti-PD-1+LAG-3 treated tumors, CD4+ T cell depletion was associated with fewer activated (CD69+) CD8+ T cells, impaired IFN{gamma} release and increased numbers of myeloid-derived suppressor cells (MDSCs) but, conversely, increased numbers of activated CD8+ T cells and IFN{gamma} release in anti-PD-1+CTLA-4 treated tumors. Analysis of relapsing melanoma brain metastases from anti-PD-1+LAG-3 treated mice showed an increased accumulation of MDSCs and a loss of gp100+ tumor reactive CD8+ T cells. An analysis of the inferred cell-cell interactions from the scRNA-seq data suggested the MDSCs interacted with multiple subsets of T cells in a bi-directional manner. ConclusionsTogether these studies suggest that these two clinically relevant ICI combinations have differential effects upon CD4+ T cell polarization, which in turn, impacted cytotoxic CD8+ T cell function. Further insights into the mechanisms of action/resistance of these clinically-relevant ICI combinations will allow therapy to be further personalized.

immunology↗

bioRxiv2023

Single Cell Transcriptomics-informed Induced Pluripotent Stem Cells Differentiation to Tenogenic Lineage

During vertebrate embryogenesis, axial tendons develop from the paraxial mesoderm and differentiate through specific developmental stages to reach the syndetome stage. While the main roles of signaling pathways in the earlier stages of the differentiation have been well established, pathway nuances in syndetome specification from the sclerotome stage have yet to be explored. Here, we show stepwise differentiation of human iPSCs to the syndetome stage using chemically defined media and small molecules that were modified based on single cell RNA-sequencing and pathway analysis. We identified a significant population of branching off-target cells differentiating towards a neural phenotype overexpressing Wnt. Further transcriptomics post-addition of a WNT inhibitor at the somite stage and onwards revealed not only total removal of the neural off-target cells, but also increased syndetome induction efficiency. Fine-tuning tendon differentiation in vitro is essential to address the current challenges in developing a successful cell-based tendon therapy.

developmental biology↗

bioRxiv2023

A longitudinal resource for population neuroscience of school-age children and adolescents in China

During the past decade, cognitive neuroscience has been calling for population diversity to address the challenge of validity and generalizability, ushering in a new era of population neuroscience. The developing Chinese Color Nest Project (devCCNP, 2013-2022), a ten-year pilot stage of the lifespan CCNP (2013-2032), is an ongoing project focusing on brain-mind development. The project aims to create and share a large-scale, longitudinal and multimodal dataset of typically developing children and adolescents (ages 6.0-17.9 at enrolment) in the Chinese population. The devCCNP houses not only phenotypes measured by demographic, biophysical, psychological and behavioural, cognitive, affective, and ocular-tracking assessments but also neurotypes measured with magnetic resonance imaging (MRI) of brain morphometry, resting-state function, naturalistic viewing function and diffusion structure. This Data Descriptor introduces the first data release of devCCNP including a total of 864 visits from 479 participants. Herein, we provided details of the experimental design, sampling strategies, and technical validation of the devCCNP resource. We demonstrate and discuss the potential of a multicohort longitudinal design to depict normative brain growth curves from the perspective of developmental population neuroscience. The devCCNP resource is shared as part of the "Chinese Data-sharing Warehouse for In-vivo Imaging Brain" in the Chinese Color Nest Project (CCNP) - Lifespan Brain-Mind Development Data Community (https://www.scidb.cn/en/c/ccnp) at the Science Data Bank. Design TypesO_LIAccelerated longitudinal design C_LIO_LIBrain-mind development C_LIO_LIPopulation imaging C_LIO_LIBrain chart C_LIO_LIRepeated measure C_LI MeasurementsO_LIPsychological behaviours C_LIO_LIBiophysical and physical measures C_LIO_LIIntelligence quotient measure C_LIO_LINeuroimaging C_LI Sample Characteristic - OrganismO_LIHomo sapiens C_LI Sample Characteristic - EnvironmentO_LISchool- and community-based sample C_LI Sample Characteristic - LocationO_LIChongqing and Beijing, China C_LI DurationO_LI10 years (2013-2022) C_LI

neuroscience↗

bioRxiv2023

StereoCell enables high accuracy single cell segmentation for spatial transcriptomic dataset

BackgroundOwing to recent advances in resolution and field-of-view, spatially resolved transcriptomics sequencing, such as Stereo-seq, has emerged as a cutting-edge technology for the interpretation of large tissues at the single-cell level. To generate accurate single-cell spatial gene expression profiles from high-resolution spatial omics data, a powerful computational tool is required. FindingsWe present CellBin, an image-facilitated one-stop pipeline for high-resolution and large field-of-view spatial transcriptomic data of Stereo-seq. CellBin provides a comprehensive and systematic platform for generating high-confidence single-cell spatial gene expression profiles, which specifically includes image stitching, image registration, tissue segmentation, nuclei segmentation and molecule labeling. CellBin is user-friendly and does not require a specific level of omics and image analysis expertise. ConclusionsDuring image stitching and molecule labeling, CellBin delivers better-performing algorithms to reduce stitching error and time, in addition to improving the signal-to-noise ratio of single-cell gene expression data, in comparison with existing methods. Additionally, CellBin has been shown to obtain highly accurate single-cell spatial data using mouse brain tissue, which facilitated clustering and annotation.

bioinformatics↗

bioRxiv2023

Recruitment of the SNX17-Retriever recycling pathway regulates synaptic function and plasticity.

Trafficking of cell-surface proteins from endosomes to the plasma membrane is a key mechanism to regulate synaptic function. In non-neuronal cells, proteins recycle to the plasma membrane either via the SNX27-Retromer-WASH pathway, or via the recently discovered SNX17-Retriever-CCC-WASH pathway. While SNX27 is responsible for the recycling of key neuronal receptors, the roles of SNX17 in neurons are less understood. Here, using cultured hippocampal neurons, we demonstrate that the SNX17 pathway regulates synaptic function and plasticity. Disruption of this pathway results in a loss of excitatory synapses and prevents structural plasticity during chemical long-term potentiation (cLTP). cLTP drives SNX17 recruitment to synapses, where its roles are in part mediated by regulating surface expression of {beta}1-integrin. SNX17 recruitment relies on NMDAR activation, CamKII signaling, and requires binding to the Retriever and PI(3)P. Together, these findings provide molecular insights into the regulation of SNX17 at synapses, and define key roles for SNX17 in synaptic maintenance and in regulating enduring forms of synaptic plasticity.

cell biology↗

bioRxiv2023

Paraburkholderia bonniea symbiont strain identity impacts amoeba host fitness and rate of horizontal transmission

In facultative symbioses, only a fraction of hosts are associated with a symbiont. Understanding why specific host and symbiont strains are associated can inform us of the evolutionary forces affecting facultative symbioses. Possibilities include ongoing host-symbiont coevolution driven by reciprocal selection, or priority effects that are neutral in respect to the host-symbiont interaction. We hypothesized that ongoing host-symbiont coevolution would lead to higher fitness estimates for naturally co-occurring (native) host and symbiont combinations compared to nonnative combinations. We used the Dictyostelium discoideum - Paraburkholderia bonniea system to test this hypothesis. P. bonniea features a reduced genome size relative to another Paraburkholderia symbiont of D. discoideum, indicating a significant history of coevolution with its host. Facultative symbionts may experience continued genome reduction if coevolution is ongoing, or their genome size may have reached a stable state if the symbiosis has also stabilized. Our work demonstrates that ongoing coevolution is unlikely for D. discoideum and P. bonniea. The system instead represents a stable facultative symbiosis. Specifically associated host and symbiont strains in this system are the result of priority effects, and presently unassociated hosts are simply uncolonized. We find evidence for a virulence-transmission trade-off without host strain specificity, and identify candidate virulence factors in the genomes of P. bonniea strains that may contribute to variation in benevolence. Lay summarySymbiotic relationships between hosts and their microbial partners are prolonged and intimate associations. Some of these relationships are obligatory for both a host and symbiont to survive, while others are facultative and each partner can survive without the other. In the latter case, some host individuals may be associated with a symbiont while others are not. Specific host and symbiont combinations can be the result of reciprocal adaptation between host and symbiont partners so that naturally co-occurring combinations are best suited for each other in terms of their biological fitness. On the other hand, the symbiont that a host is associated with may simply be the symbiont that arrived first, in what is called a priority effect. We sought to determine which possibility best explained naturally co-occurring combinations of host and symbiont strains of the social amoeba Dictyostelium discoideum and its symbiont Paraburkholderia bonniea. Our work demonstrates that D. discoideum and P. bonniea are in a stable facultative relationship. Specifically associated host and symbiont combinations are the result of priority effects, and D. discoideum hosts without symbionts are simply uncolonized. This work fills a gap in our understanding of the evolutionary forces affecting facultative symbiotic relationships. We also show for the first time that P. bonniea symbionts can spread among amoeba hosts when they aggregate together during the social stage of their life cycle.

evolutionary biology↗

bioRxiv2023

Development of a human glioblastoma model using humanized DRAG mice for immunotherapy

Glioblastoma (GBM) is the most common and lethal primary brain tumor with high mortality rates and a short median survival rate of about 15 months despite intensive multimodal treatment of maximal surgical resection, radiotherapy, and chemotherapy. Although immunotherapies have been successful in the treatment of various cancers, disappointing results from clinical trials for GBM immunotherapy represent our incomplete understanding. The development of alternative humanized mouse models with fully functional human immune cells will potentially accelerate the progress of GBM immunotherapy. In this study, we developed a humanized DRAG (NOD.Rag1KO.IL2R{gamma}cKO) mouse model, in which the human hematopoietic stem cells (HSCs) were well-engrafted and subsequently differentiated into a full lineage of immune cells. Using this humanized DRAG mouse model, GBM patient-derived tumorsphere lines were successfully engrafted to form xenografted tumors, which can recapitulate the pathological features and the immune cell composition of human GBM. Importantly, the administration of anti-human PD-1 antibodies in these DRAG mice bearing a GBM patient-derived tumorsphere line resulted in decreasing the major tumor-infiltrating immunosuppressive cell populations, including CD4+PD-1+ and CD8+PD-1+ T cells, CD11b+CD14+HLA-DR+ macrophages, CD11b+CD14+HLA-DR-CD15- and CD11b+CD14- CD15+ myeloid-derived suppressor cells, indicating the humanized DRAG mouse model as a useful model to test the efficacy of immune checkpoint inhibitors in GBM immunotherapy. Together, these results suggest that humanized DRAG mouse models are a reliable preclinical platform for brain cancer immunotherapy and beyond.

cancer biology↗

bioRxiv2023

POLG genotype influences degree of mitochondrial dysfunction in iPSC derived neural progenitors, but not the parent iPSC or derived glia

Diseases caused by POLG mutations are the most common form of mitochondrial disease and associated with phenotypes of varying severity. Clinical studies have shown that patients with compound heterozygous POLG mutations have a lower survival rate than patients with homozygous mutations, but the molecular mechanisms behind this remain unexplored. Using an induced pluripotent stem cell (iPSC) model, we investigate differences between homozygous and compound heterozygous genotypes in different cell types, including patient-specific fibroblasts, iPSCs, and iPSC-derived neural stem cells (NSCs) and astrocytes. We found that compound heterozygous lines exhibited greater impairment of mitochondrial function in NSCs than homozygous NSCs, but not in fibroblasts, iPSCs, or astrocytes. Compared with homozygous NSCs, compound heterozygous NSCs exhibited more severe functional defects, including reduced ATP production, loss of mitochondrial DNA (mtDNA) copy number and complex I expression, disturbance of NAD+ metabolism, and higher ROS levels, which further led to cellular senescence and activation of mitophagy. RNA sequencing analysis revealed greater downregulation of mitochondrial and metabolic pathways, including the citric acid cycle and oxidative phosphorylation, in compound heterozygous NSCs. Our iPSC-based disease model can be widely used to understand the genotype-phenotype relationship of affected brain cells in mitochondrial diseases, and further drug discovery applications. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/526021v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@ce1761org.highwire.dtl.DTLVardef@610ed3org.highwire.dtl.DTLVardef@1460b0org.highwire.dtl.DTLVardef@1d7fd53_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

DNA G-quadruplex is a transcriptional control device that regulates memory

The conformational state of DNA fine-tunes the transcriptional rate and abundance of RNA. Here we report that DNA G-quadruplex (G4-DNA) accumulates in neurons in an experience-dependent manner, and that this is required for the transient silencing and activation of genes that are critically involved in learning and memory. In addition, site-specific resolution of G4-DNA by dCas9-mediated deposition of the helicase DHX36 impairs fear extinction memory. Dynamic DNA structure states therefore represent a key molecular mechanism underlying memory consolidation. One-Sentence SummaryG4-DNA is a molecular switch that enables the temporal regulation of the gene expression underlying the formation of fear extinction memory.

neuroscience↗