Biology subjects

Ma, D.

Publications and source records attributed to Ma, D..

At least 55 records · Page 3Linked to original sources

bioRxiv2024

Novel clock neuron subtypes regulate temporal aspects of sleep

Circadian neurons within animal brains orchestrate myriad physiological processes and behaviors, But the contribution of these neurons to the regulation of sleep is not well understood. To address this deficiency, we leveraged single-cell RNA sequencing to generate a new and now comprehensive census of transcriptomic cell types of Drosophila clock neurons. We focused principally on the enigmatic DN3s, which constitute about half of the 75 pairs of clock neurons in the fly brain and were previously almost completely uncharacterized. These DN3s are organized into 12 clusters with unusual gene expression features compared to the more well-studied clock neurons. We further show that different DN3 subtypes with distinct projection patterns promote sleep at specific times of the day through a common G protein-coupled receptor, TrissinR. Our findings indicate an intricate regulation of sleep behavior by clock neurons and highlight their remarkable diversity in gene expression, projection patterns and functional properties.

neuroscience↗

bioRxiv2024

Comprehensive analysis across mammalian tissues and cells decipher the underlying mechanism of m6A specificity

N6-methyladenine (m6A) stands out as the most prevalent internal chemical modification on mammalian mRNA, playing a vital role in diverse biological processes. Despite considerable advancements in individual cell line studies, the characteristics of m6A sites across distinct cell lines or tissues remain elusive. In this study, we have successfully identified approximately 1.5 million high-confidence m6A sites in human and mouse cell lines or tissues using published m6A-seq data. By categorizing m6A sites into different consistency levels, we observe that those of high consistency are notably enriched near the stop codon. Furthermore, they exhibit a higher likelihood of interaction with known m6A binding proteins such as YTHDF1-3, RBM15, YTHDC1, and IGF2BP1, thereby influencing gene expression homeostasis. Additionally, these sites display a higher CpG density in the promoter region of the genes they mark, with METTL3 demonstrating a preference for binding to the promoter region of its marked genes. m6A sites of low consistency levels, including unique m6A sites, show a significant enrichment near the start codon. These sites are more prone to binding by newly discovered m6A-binding proteins such as DDX3X, PRPF8, and EIF3G. The identification of these distinct features of m6A sites lays a foundational understanding for unraveling the functional roles of m6A.

bioinformatics↗

bioRxiv2024

Light and dopamine impact two circadian neurons to promote morning wakefulness

In both mammals and flies, circadian brain neurons orchestrate physiological oscillations and behaviors like wake and sleep; these neurons can be subdivided by morphology and by gene expression patterns. Recent single-cell sequencing studies identified 17 Drosophila circadian neuron groups. One of these include only two lateral neurons (LNs), which are marked by the expression of the neuropeptide ion transport peptide (ITP). Although these two ITP+ LNs have long been grouped with five other circadian evening activity cells, inhibiting the two neurons alone strongly reduces morning activity; this indicates that they are prominent morning neurons. As dopamine signaling promotes activity in Drosophila like in mammals, we considered that dopamine might influence this morning activity function. Moreover, the ITP+ LNs express higher mRNA levels than other LNs of the type 1-like dopamine receptor Dop1R1. Consistent with the importance of Dop1R1, CRISPR/Cas9 mutagenesis of this receptor only in the two ITP+ LNs renders flies significantly less active in the morning, and ex vivo live imaging shows that dopamine increases cAMP levels in these two neurons; cell-specific mutagenesis of Dop1R1 eliminates this cAMP response to dopamine. Notably, the response is more robust in the morning, reflecting higher morning Dop1R1 mRNA levels in the two neurons. As morning levels are not elevated in constant darkness, this suggests light-dependent upregulation of morning Dop1R1 transcript levels. Taken together with enhanced morning cAMP response to dopamine, the data indicate how light stimulates morning wakefulness in flies, which mimics the important effect of light on morning wakefulness in humans.

neuroscience↗

bioRxiv2024

Ultraviolet attenuates centromere-mediated meiotic genome stability and alters gametophytic ploidy consistency in flowering plants

Ultraviolet (UV) radiation influences development and genome stability in organisms; however, its impacts on meiosis, a special cell division essential for the delivery of genetic information over generations in eukaryotes, remain not yet elucidated. In this study, we demonstrate that UV attenuates the centromere-mediated meiotic chromosome stability and induces unreduced gametes in Arabidopsis thaliana. We show that UV reduces crossover (CO) rate but does not interfere with meiotic chromosome integrity. Functional centromere-specific histone 3 (CENH3) is required for the obligate CO formation, and plays a role in protection of homolog synapsis and sister-chromatid cohesion under UV stress. Moreover, UV specifically alters the orientation and organization of spindles and phragmoplasts at meiosis II, resulting in meiotic restitution and unreduced gametes. Further, we determine that UV-induced meiotic restitution does not rely on the UV Resistance Locus8-mediated UV perception and the Tapetal Development and Function1- and Aborted Microspores-dependent tapetum development, but occurs possibly via impacted JASON function and downregulated Parallel Spindle1. This study sheds light on the impacts of UV on meiotic genome stability and gametophytic ploidy consistency, which thus may influence genome evolution in flowering plants.

plant biology↗

bioRxiv2024

Arl2 Associates with Cdk5rap2 to Regulate Cortical Development via Microtubule Organization

ADP ribosylation factor-like GTPase 2 (Arl2) is crucial for controlling mitochondrial fusion and microtubule assembly in various organisms. Arl2 regulates the asymmetric division of neural stem cells in Drosophila via microtubule growth. However, the function of mammalian Arl2 during cortical development was unknown. Here, we demonstrate that mouse Arl2 plays a new role in corticogenesis via regulating microtubule growth, but not mitochondria functions. Arl2 knockdown leads to impaired proliferation of neural progenitor cells (NPCs) and neuronal migration. Arl2 knockdown in mouse NPCs significantly diminishes centrosomal microtubule growth and delocalization of centrosomal proteins Cdk5rap2 and {gamma}-tubulin. Moreover, Arl2 physically associates with Cdk5rap2 by in silico prediction using AlphaFold Multimer and in vitro binding assays. Remarkably, Cdk5rap2 overexpression significantly rescues the neurogenesis defects caused by Arl2 knockdown. Therefore, Arl2 plays an important role in mouse cortical development through microtubule growth via the centrosomal protein Cdk5rap2.

neuroscience↗

bioRxiv2024

Generalizable Quantum Computing Pipeline for Real World Drug Discovery

Quantum computing, with its superior computational capabilities compared to classical approaches, holds the potential to revolutionize numerous scientific domains, including pharmaceuticals. However, the application of quantum computing for drug discovery has primarily been limited to proof-of-concept studies, which often fail to capture the intricacies of real-world drug development challenges. In this study, we diverge from conventional investigations by developing an advanced quantum computing pipeline tailored to address genuine drug design problems. Our approach underscores the pragmatic application of quantum computation and propels it towards practical industrial adoption. We specifically construct our versatile quantum computing pipeline to address two critical tasks in drug discovery: the precise determination of Gibbs free energy profiles for prodrug activation involving covalent bond cleavage, and the accurate simulation of covalent bond interactions. This work serves as a pioneering effort in benchmarking quantum computing against veritable scenarios encountered in drug design, especially the covalent bonding issue present in both of the case studies, thereby transitioning from theoretical models to tangible applications. Our results demonstrate the potential of a quantum computing pipeline for integration into real world drug design workflows.

bioinformatics↗

bioRxiv2024

Lateral Flow Assays Biotesting by Utilizing Plasmonic Nanocrystals Made of Inexpensive Metals - Replacing Gold

Nanoparticles (NPs) can be conjugated with diverse biomolecules and employed in biosensing to detect target analytes in biological samples. This proven concept was primarily used during the COVID-19 pandemic with gold NPs-based lateral flow assays (LFAs). Considering the gold price and its worldwide depletion, here we show that novel plasmonic nanoparticles (NPs) based on inexpensive metals, titanium nitride (TiN) and copper covered with a gold shell (Cu@Au), perform comparable or even better than gold nanoparticles. After conjugation, these novel nanoparticles provided high figures of merit for LFA testing, such as high signals and specificity and robust naked-eye signal recognition. To the best of our knowledge, our study represents the 1st application of laser-ablation-fabricated nanoparticles (TiN) in the LFA and dot-blot biotesting. Since the main cost of the Au NPs in commercial testing kits is in the colloidal synthesis, our development with TiN is very exciting, offering potentially very inexpensive plasmonic nanomaterials for various bio-testing applications. Moreover, our machine learning study showed that the bio-detection with TiN is more accurate than that with Au.

biophysics↗

bioRxiv2023

SntB triggers the antioxidant pathways to regulate development and aflatoxin biosynthesis in Aspergillus flavus

The epigenetic reader SntB was identified as an important transcriptional regulator of growth, development, and secondary metabolite synthesis in Aspergillus flavus. However, the underlying molecular mechanism is still unclear. In this study, sntB gene deletion ({Delta}sntB), complementary (Com-sntB), and HA tag fused to sntB (sntB-HA) strains were constructed by using the homologous recombination method, respectively. Our results revealed that deletion of sntB inhibited the processes of mycelia growth, conidial production, sclerotia formation, aflatoxin synthesis, and ability to colonize host, and the defective phenotype of knockout strain {Delta}sntB could be restored in its complementary strain Com-sntB. Chromatin immunoprecipitation sequencing (ChIP-seq) of sntB-HA and WT, and RNA sequencing (RNA-seq) of {Delta}sntB and WT strains revealed that SntB played key roles in oxidative stress response of A. flavus. The function of catC gene (encode a catalase) was further analyzed based on the integration results of ChIP-seq and RNA-seq. In {Delta}sntB strain, the relative expression level of catC was significantly higher than in WT strain, while a secretory lipase encoding gene (G4B84_008359) was down-regulated. Under the stress of oxidant menadione sodium bisulfite (MSB), the deletion of sntB obvious down-regulated the expression level of catC. After deletion of catC gene, the mycelia growth, conidial production, and sclerotia formation were inhibited, while ROS level and aflatoxin production were increased compared to the WT strain. Results also showed that the inhibition rate of MSB to {Delta}catC strain was significantly lower than that of WT group and AFB1 yield of the {Delta}catC strain was significantly decreased than that of WT strain under the stress of MSB. Our study revealed the potential machinery that SntB regulated fungal morphogenesis, mycotoxin anabolism, and fungal virulence through the axle of from SntB to fungal virulence and mycotoxin bio-synthesis, i.e. H3K36me3 modification-SntB-Peroxisomes-Lipid hydrolysis-fungal virulence and mycotoxin bio-synthesis. The results of this study shed light into the SntB mediated transcript regulation pathways of fungal mycotoxin anabolism and virulence, which provided potential strategy for control the contamination of A. flavus and its aflatoxins.

pharmacology and toxicology↗

bioRxiv2023

Dense Sampling of Taxa and Genomes Untangles the Phylogenetic Backbone of a Non-model Plant Lineage Rife with Deep Hybridization and Allopolyploidy

Phylogenetic networks, rather than purely bifurcating trees, more accurately depict the intricate evolutionary dynamics of most lineages, especially those characterized by extensive hybridization and allopolyploidization events. However, the challenges of achieving complete taxon sampling, and limited financial resources for studying non-model plant lineages, have hindered comprehensive and robust estimation of phylogenetic backbones with guidance from networks. The bellflower tribe, Campanuleae, characterized by a reticulate evolutionary history, serves as an ideal model to investigate how to diagnose nested ancient reticulation events. Here, by integrating multiple genomic data sources and a range of phylogenetic inference methods, we produced a robust phylogenetic backbone for the tribe Campanuleae. Our investigation of reticulate evolution indicates that hybridization and allopolyploidization were instrumental in shaping the diversity of the bellflower tribe, particularly during the initial diversification of the subtribe Phytematinae. Additionally, we ascertained that conflicting topologies resulting from distinct genomic datasets and inference methodologies significantly impact downstream estimates of divergence dating, ancestral area construction, and diversification rates. This study offers a universally relevant framework for deciphering how to use network-based phylogenetic structures using various genomic sources and inference methods. [Campanulaceae, Campanuleae, Cytonuclear discordance, paralog, phylogenomics, reticulate evolution]

plant biology↗

bioRxiv2023

Glymphatic Inhibition Exacerbates Tau Propagation in an Alzheimers Disease Model

BackgroundThe aggregation and spread of misfolded amyloid structured proteins, such as tau and -synuclein, are key pathological features associated with neurodegenerative disorders, including Alzheimers and Parkinsons disease. These proteins possess a prion-like property, enabling their transmission from cell to cell leading to propagation throughout the central and peripheral nervous systems. While the mechanisms underlying their intracellular spread are still being elucidated, targeting the extracellular space has emerged as a potential therapeutic approach. The glymphatic system, a brain-wide pathway responsible for clearing extracellular metabolic waste from the central nervous system, has gained attention as a promising target for removing these toxic proteins. MethodsIn this study, we investigated the impact of long-term modulation of glymphatic function on tau aggregation and spread by chronically treating a mouse model of tau propagation with a pharmacological inhibitor of AQP4, TGN-020. Thy1-hTau.P301S mice were intracerebrally inoculated with tau into the hippocampus and overlying cortex, and subsequently treated with TGN-020 (3 doses/week, 50mg/kg TGN-020, i.p.) for 10-weeks. During this time, animal memory was studied using cognitive behavioural tasks, and structural MR images were acquired of the brain in vivo prior to brain extraction for immunohistochemical characterisation. ResultsOur findings demonstrate increased tau aggregation in the brain and transhemispheric propagation in the hippocampus and cortex following the inhibition of glymphatic clearance. Moreover, disruption of the glymphatic system aggravated recognition memory in tau inoculated mice and exacerbated regional changes in brain volume detected in the model. When initiation of drug treatment was delayed for several weeks post-inoculation, the aforementioned alterations were attenuated. ConclusionsThese results indicate that by modulating AQP4 function and, consequently, glymphatic clearance, it is possible to modify the propagation and pathological impact of tau in the brain, particularly during the initial stages of the disease. These findings highlight the critical role of the glymphatic system in preserving healthy brain homeostasis and offer valuable insights into the therapeutic implications of targeting this system for managing neurodegenerative diseases characterized by protein aggregation and spread.

neuroscience↗

bioRxiv2023

Investigating Brain Alterations in the Dp1Tyb Mouse Model of Down Syndrome

Down syndrome (DS) is one of the most common birth defects and the most prevalent genetic form of intellectual disability. DS arises from trisomy of chromosome 21, but its molecular and pathological consequences are not fully understood. In this study, we compared Dp1Tyb mice, a DS model, against their wild-type (WT) littermates of both sexes to investigate the impact of DS-related genetic abnormalities on the brain phenotype. We performed in vivo whole brain magnetic resonance imaging (MRI) and hippocampal 1H magnetic resonance spectroscopy (MRS) on the animals at 3 months of age. Subsequently, ex vivo MRI scans and histological analyses were conducted post-mortem. Our findings unveiled distinct neuroanatomical and biochemical alterations in the Dp1Tyb brains. Dp1Tyb brains exhibited a smaller surface area and a rounder shape compared to WT brains. Regional volumetric analysis revealed significant changes in 26 out of 72 examined brain regions, including the medial prefrontal cortex and dorsal hippocampus. These alterations were consistently observed in both in vivo and ex vivo imaging data. Additionally, high-resolution ex vivo imaging enabled us to investigate cerebellar layers and hippocampal subregions, revealing selective areas of decrease and remodelling in these structures. An analysis of hippocampal metabolites revealed an elevation in glutamine and the glutamine/glutamate ratio in the Dp1Tyb mice compared to controls, suggesting a possible imbalance in the excitation/inhibition ratio. This was accompanied by the decreased levels of taurine. Histological analysis revealed fewer neurons in the hippocampal CA3 and DG layers, along with an increase in astrocytes and microglia. These findings recapitulate multiple neuroanatomical and biochemical features associated with DS, enriching our understanding of the potential connection between chromosome 21 trisomy and the resultant phenotype.

neuroscience↗

bioRxiv2023

Broadly effective ACE2 decoy proteins protect mice from lethal SARS-CoV-2 infection

As SARS-CoV-2 variants have been causing increasingly serious drug resistance problem, development of broadly effective and hard-to-escape anti-SARS-CoV-2 agents is in urgent need. Here we describe further development and characterization of two SARS-CoV-2 receptor decoy proteins, ACE2-Ig-95 and ACE2-Ig-105/106. We found that both proteins had potent and robust in vitro neutralization activities against diverse SARS-CoV-2 variants including Omicron, with an average IC50 of up to 37 pM. In a stringent lethal SARS-CoV-2 infection mouse model, both proteins lowered lung viral load by up to [~]1000 fold, prevented the emergence of clinical signs in >75% animals, and increased animal survival rate from 0% (untreated) to >87.5% (treated). These results demonstrate that both proteins are good drug candidates for protecting animals from severe COVID-19. In a head-to-head comparison of these two proteins with five previously-described ACE2-Ig constructs, we found that two of these constructs, each carrying five surface mutations in the ACE2 region, had partial loss of neutralization potency against three SARS-CoV-2 variants. These data suggest that extensively mutating ACE2 residues near the RBD-binding interface should be avoided or performed with extra caution. Further, we found that both ACE2-Ig-95 and ACE2-Ig-105/106 could be produced to gram/liter level, demonstrating the developability of them as biologic drug candidates. Stress-condition stability test of them further suggests that more studies are required in the future to improve the stability of these proteins. These studies provide useful insight into critical factors for engineering and preclinical development of ACE2 decoys as broadly effective therapeutics against diverse ACE2-utilizing coronaviruses. Abstract ImportanceEngineering soluble ACE2 proteins that function as a receptor decoy to block SARS-CoV-2 infection is a very attractive approach to broadly effective and hard-to-escape anti-SARS-CoV-2 agents. This study here describes development of two antibody-like soluble ACE2 proteins that broadly block diverse SARS-CoV-2 variants including Omicron. In a stringent COVID-19 mouse model, both proteins successfully protected >87.5% animals from lethal SARS-CoV-2 infection. In addition, a head-to-head comparison of the two constructs developed in this study with five previously-described ACE2 decoy constructs were performed here. Two previously-described constructs with relatively more ACE2-surface mutations were found with less robust neutralization activities against diverse SARS-CoV-2 variants. Further, the developability of the two proteins as biologic drug candidates was also assessed here. This study provides two broadly anti-SARS-CoV-2 drug candidates and useful insight into critical factors for engineering and preclinical development of ACE2 decoy as broadly effective therapeutics against diverse ACE2-utilizing coronaviruses. TweetTwo antibody-like ACE2 decoy proteins could block diverse SARS-CoV-2 variants and prevent animals from severe COVID-19.

microbiology↗

bioRxiv2022

Haploid-resolved and chromosome-scale genome assembly in hexa-autoploid sweetpotato (Ipomoea batatas (L.) Lam)

Sweetpotato (Ipomoea batatas (L.) Lam) is the worlds seventh most important food crop by production quantity. Cultivated sweetpotato is a hexaploid (2n = 6x = 90), and its genome (B1B1B2B2B2B2) is quite complex due to polyploidy, self-incompatibility, and high heterozygosity. Here we established a haploid-resolved and chromosome-scale de novo assembly of autohexaploid sweetpotato genome sequences. Before constructing the genome, we created chromosome-scale genome sequences in I. trifida using a highly homozygous accession, Mx23Hm, with PacBio RSII and Hi-C reads. Haploid-resolved genome assembly was performed for a sweetpotato cultivar, Xushu18 by hybrid assembly with Illumina paired-end (PE) and mate-pair (MP) reads, 10X genomics reads, and PacBio RSII reads. Then, 90 chromosome-scale pseudomolecules were generated by aligning the scaffolds onto a sweetpotato linkage map. De novo assemblies were also performed for chloroplast and mitochondrial genomes in I. trifida and sweetpotato. In total, 34,386 and 175,633 genes were identified on the assembled nucleic genomes of I. trifida and sweetpotato, respectively. Functional gene annotation and RNA-Seq analysis revealed locations of starch, anthocyanin, and carotenoid pathway genes on the sweetpotato genome. This is the first report of chromosome-scale de novo assembly of the sweetpotato genome. The results are expected to contribute to genomic and genetic analyses of sweetpotato.

genomics↗

bioRxiv2022

Small cytosolic dsDNAs repress cGAS activation and induce autophagy

Cyclic GMP-AMP (cGAMP) synthase (cGAS), a major cytosolic DNA sensor, activates innate immune responses by producing cGAMP, which activates stimulator of interferon genes (STING)1. Cytosolic DNA induces autophagy in a cGAS-dependent manner to avoid persistent immune stimulation. Although dsDNAs < 20 bp can bind to cGAS, robust cGAS activation requires dsDNAs > 45 bp 2-4. However, whether cytosolic dsDNAs < 45 bp exist in mammalian cells remains unclear. Here, we identified a class of small cytosolic DNAs (scDNAs) of [~]20-40 bp in human and mouse cell lines. scDNAs competed with herring testis DNA (HT-DNA, [~]200-1500 bp) for binding to cGAS, and repressing HT-DNA-induced cGAS activation and the associated interferon {beta} (IFN{beta}) production. Moreover, scDNAs promoted cGAS and Beclin-1 interaction, triggering the release of Rubicon, a negative regulator of phosphatidylinositol 3-kinase class III (PI3KC3)5,6, from the Beclin-1-PI3KC3 complex, activating PI3KC3 and inducing autophagy. DNA damage decreased and autophagy inducers increased scDNA levels. scDNA transfection or autophagy induction attenuated DNA damage-induced cGAS-STING activation and IFN{beta} expression. Thus, scDNAs acted as molecular brakes of cGAS activation, preventing excessive inflammatory cytokine production following DNA damage. Our findings lay foundations for understanding the physiological and pathological functions of scDNAs.

molecular biology↗

bioRxiv2022

Single-base precision design of CRISPR-Cas13b enables systematic silencing of oncogenic fusions

Precision oncology programs can rapidly identify oncogenic gene fusions in individual patients1-3. However, despite their established oncogenic status, the vast majority of gene fusions remain undruggable due to the lack of specific inhibitory molecules4, 5. Here, we establish PspCas13b, a poorly characterized programmable RNA nuclease, as a versatile tool to silence various oncogenic fusion transcripts. Our Single-Base Tiled crRNA screens (SiBTil), unbiased computational analysis, and comprehensive spacer-target mutagenesis revealed key determinants of PspCas13b activity. De novo design of crRNAs harbouring basepaired or mismatched guanosine bases at key spacer positions greatly enhances the silencing efficacy of otherwise inefficient crRNAs, expanding the targeting spectrum of this enzyme. We also reveal the interface between mismatch tolerance and intolerance, which unlocks an unexpected single-base precision targeting capability of this RNA nuclease. Notably, our de novo design principles enable potent and selective silencing of various gene fusion transcripts and their downstream oncogenic networks, without off-targeting of non-translocated variants that share extensive sequence homology. We demonstrate that PspCas13b targeting the breakpoint of fusion transcripts enables efficient suppression of ancestral and single-nucleotide mutants (e.g. BCR-ABL1 T315I) that often drive clinical cancer relapse. Collectively, this study provides new design principles for PspCas13b programming to specifically recognise and degrade any undruggable fusion oncogenic transcript, thus providing a new conceptual framework for personalized oncology.

molecular biology↗

bioRxiv2022

Small molecule mediated stabilization of PP2A modulates the Homologous Recombination pathway and potentiates DNA damage-induced cell death

High-Grade Serous Carcinoma (HGSC) is the most common and lethal ovarian cancer subtype. PARP-inhibitors (PARPi) have become the mainstay of HGSC targeted therapy, given that these tumors are driven by a high degree of genomic instability and Homologous Recombination (HR) defects. Nonetheless, only [~]30% of patients initially respond to treatment, ultimately relapsing with resistant disease. Thus, despite recent advances in drug development and increased understanding of genetic alterations driving HGSC progression, mortality has not declined, highlighting the need for novel therapies. Using a Small Molecule Activator of Protein Phosphatase 2A (PP2A) (SMAP-061), we investigated the mechanism by which PP2A stabilization induces apoptosis in Patient-Derived HGSC cells and Xenograft (PDX) models alone or in combination with PARPi. We uncovered that PP2A genes essential for transformation (B56,B56{gamma} and PR72) and basal phosphatase activity (PP2A-A and -C) are heterozygously lost in the majority of HGSC. Moreover, loss of these PP2A genes correlates with worse overall patient survival. We show that SMAP-061 stabilization of PP2A inhibits the HR output by targeting RAD51, leading to chronic accumulation of DNA damage and ultimately apoptosis. Furthermore, combination of SMAP-061 and PARPi leads to enhanced apoptosis in both HR-proficient and -deficient cells and in patient-derived xenograft models. Our studies identify PP2A as novel regulator of HR and introduces PP2A activators as a potential treatment for HGSC tumors. Our studies further emphasize the potential of PP2A modulators to overcome PARPi insensitivity, given that targeting RAD51 has presented benefits in overcoming PARPi-resistance driven by BRCA1/2 mutation reversions.

cancer biology↗

bioRxiv2022

Neural connectivity molecules best identify the heterogeneous clock and dopaminergic cell types in the Drosophila adult brain

Our recent single cell sequencing of most adult Drosophila circadian neurons indicated striking gene expression heterogeneity, about 2-3 cells per clock neuron group. To extend this characterization to other adult fly brain neurons, we used the identical plate-based methods to generate single cell data from a similar subset of dopaminergic neurons. To minimize batch effects and to apply an additional sequencing strategy, we also assayed these two populations together with 10X Chromium. An unsupervised clustering algorithm indicates that dopaminergic neurons are comparably heterogeneous, suggesting that the transcriptomic diversity of adult fly brain neurons parallels its EM connectome. The results here further indicate that connectivity molecules like cell surface molecules best characterize all neuron groups. We suggest that these surprising features are general and make major contributions to neuronal identity and connectivity of the adult central brain as well as underlie the complex behavioral repertoire of Drosophila.

neuroscience↗

bioRxiv2022

Medial prefrontal cortex Notch1 signalling mediates methamphetamine-induced psychosis via Hes1-dependent suppression of GABAB1 receptor expression.

Methamphetamine (METH), a widely abused stimulant drug, induces psychosis in approximately half of abusers; this effect is becoming a major concern for society. Although the Notch1 signalling pathway has been shown to play a part in the pathogenesis of some psychiatric disorders, its role in METH-induced psychosis (MIP) is still unknown. Here, we showed that Notch1 signalling was downregulated in the medial prefrontal cortex (mPFC) in a MIP mouse model. Direct genetic and pharmacological manipulations of Notch1 signalling bidirectionally altered MIP-related behaviours and governed neuronal activity in the mPFC. Moreover, Notch1 signalling negatively regulated GABAB1 receptor expression in the mPFC of MIP mice through Hes1, a transcriptional repressor in Notch1 signalling. Further, we show that Hes1 can directly bind to the GABAB1 receptor promoter. Notably, pharmacological regulation of the GABAB receptor in the mPFC reversed the changes in MIP-related behaviours caused by the dysfunction of Notch1 signalling. Together, our findings uncover a previously unrecognised Notch1-Hes1-GABAB1 receptor-dependent mechanism involved in regulating mPFC neuronal activity and behavioural phenotypes in MIP. Our work provides mechanistic insight into the aetiology and pathophysiology of MIP.

molecular biology↗