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1.
Cell ; 2024 Oct 14.
Article in English | MEDLINE | ID: mdl-39419025

ABSTRACT

Chemotherapy is often combined with immune checkpoint inhibitor (ICIs) to enhance immunotherapy responses. Despite the approval of chemo-immunotherapy in multiple human cancers, many immunologically cold tumors remain unresponsive. The mechanisms determining the immunogenicity of chemotherapy are elusive. Here, we identify the ER stress sensor IRE1α as a critical checkpoint that restricts the immunostimulatory effects of taxane chemotherapy and prevents the innate immune recognition of immunologically cold triple-negative breast cancer (TNBC). IRE1α RNase silences taxane-induced double-stranded RNA (dsRNA) through regulated IRE1-dependent decay (RIDD) to prevent NLRP3 inflammasome-dependent pyroptosis. Inhibition of IRE1α in Trp53-/- TNBC allows taxane to induce extensive dsRNAs that are sensed by ZBP1, which in turn activates NLRP3-GSDMD-mediated pyroptosis. Consequently, IRE1α RNase inhibitor plus taxane converts PD-L1-negative, ICI-unresponsive TNBC tumors into PD-L1high immunogenic tumors that are hyper-sensitive to ICI. We reveal IRE1α as a cancer cell defense mechanism that prevents taxane-induced danger signal accumulation and pyroptotic cell death.

2.
Cell ; 184(14): 3731-3747.e21, 2021 07 08.
Article in English | MEDLINE | ID: mdl-34214470

ABSTRACT

In motor neuroscience, state changes are hypothesized to time-lock neural assemblies coordinating complex movements, but evidence for this remains slender. We tested whether a discrete change from more autonomous to coherent spiking underlies skilled movement by imaging cerebellar Purkinje neuron complex spikes in mice making targeted forelimb-reaches. As mice learned the task, millimeter-scale spatiotemporally coherent spiking emerged ipsilateral to the reaching forelimb, and consistent neural synchronization became predictive of kinematic stereotypy. Before reach onset, spiking switched from more disordered to internally time-locked concerted spiking and silence. Optogenetic manipulations of cerebellar feedback to the inferior olive bi-directionally modulated neural synchronization and reaching direction. A simple model explained the reorganization of spiking during reaching as reflecting a discrete bifurcation in olivary network dynamics. These findings argue that to prepare learned movements, olivo-cerebellar circuits enter a self-regulated, synchronized state promoting motor coordination. State changes facilitating behavioral transitions may generalize across neural systems.


Subject(s)
Movement/physiology , Nerve Net/physiology , Action Potentials/physiology , Animals , Calcium/metabolism , Cerebellum/physiology , Cortical Synchronization , Forelimb/physiology , Interneurons/physiology , Learning , Mice, Inbred C57BL , Mice, Transgenic , Models, Neurological , Motor Activity/physiology , Olivary Nucleus/physiology , Optogenetics , Purkinje Cells/physiology , Stereotyped Behavior , Task Performance and Analysis
3.
Cell ; 174(6): 1436-1449.e20, 2018 09 06.
Article in English | MEDLINE | ID: mdl-30146163

ABSTRACT

Synaptic vesicle and active zone proteins are required for synaptogenesis. The molecular mechanisms for coordinated synthesis of these proteins are not understood. Using forward genetic screens, we identified the conserved THO nuclear export complex (THOC) as an important regulator of presynapse development in C. elegans dopaminergic neurons. In THOC mutants, synaptic messenger RNAs are retained in the nucleus, resulting in dramatic decrease of synaptic protein expression, near complete loss of synapses, and compromised dopamine function. CRE binding protein (CREB) interacts with THOC to mark synaptic transcripts for efficient nuclear export. Deletion of Thoc5, a THOC subunit, in mouse dopaminergic neurons causes severe defects in synapse maintenance and subsequent neuronal death in the substantia nigra compacta. These cellular defects lead to abrogated dopamine release, ataxia, and animal death. Together, our results argue that nuclear export mechanisms can select specific mRNAs and be a rate-limiting step for neuronal differentiation and survival.


Subject(s)
Caenorhabditis elegans Proteins/genetics , Dopaminergic Neurons/metabolism , Nuclear Proteins/genetics , Synapses/metabolism , Active Transport, Cell Nucleus , Amyotrophic Lateral Sclerosis/metabolism , Amyotrophic Lateral Sclerosis/pathology , Animals , Caenorhabditis elegans , Caenorhabditis elegans Proteins/metabolism , Calcium Signaling , Cell Nucleus/metabolism , Cyclic AMP Response Element-Binding Protein/genetics , Cyclic AMP Response Element-Binding Protein/metabolism , Female , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Mutagenesis , Mutation, Missense , Nuclear Proteins/deficiency , Nuclear Proteins/metabolism , Protein Subunits/deficiency , Protein Subunits/genetics , Protein Subunits/metabolism
4.
Cell ; 168(1-2): 86-100.e15, 2017 Jan 12.
Article in English | MEDLINE | ID: mdl-27916275

ABSTRACT

Type 1 diabetes is characterized by the destruction of pancreatic ß cells, and generating new insulin-producing cells from other cell types is a major aim of regenerative medicine. One promising approach is transdifferentiation of developmentally related pancreatic cell types, including glucagon-producing α cells. In a genetic model, loss of the master regulatory transcription factor Arx is sufficient to induce the conversion of α cells to functional ß-like cells. Here, we identify artemisinins as small molecules that functionally repress Arx by causing its translocation to the cytoplasm. We show that the protein gephyrin is the mammalian target of these antimalarial drugs and that the mechanism of action of these molecules depends on the enhancement of GABAA receptor signaling. Our results in zebrafish, rodents, and primary human pancreatic islets identify gephyrin as a druggable target for the regeneration of pancreatic ß cell mass from α cells.


Subject(s)
Artemisinins/pharmacology , Diabetes Mellitus, Type 1/drug therapy , Disease Models, Animal , Receptors, GABA-A/metabolism , Signal Transduction , Animals , Artemether , Artemisinins/administration & dosage , Carrier Proteins/metabolism , Cell Transdifferentiation/drug effects , Cells, Cultured , Diabetes Mellitus/drug therapy , Diabetes Mellitus, Type 1/pathology , Gene Expression Profiling , Homeodomain Proteins/metabolism , Humans , Insulin/genetics , Insulin/metabolism , Islets of Langerhans/drug effects , Membrane Proteins/metabolism , Mice , Protein Stability/drug effects , Rats , Single-Cell Analysis , Transcription Factors/metabolism , Zebrafish , gamma-Aminobutyric Acid/metabolism
5.
Cell ; 167(6): 1650-1662.e15, 2016 Dec 01.
Article in English | MEDLINE | ID: mdl-27912066

ABSTRACT

Electrophysiological field potential dynamics are of fundamental interest in basic and clinical neuroscience, but how specific cell types shape these dynamics in the live brain is poorly understood. To empower mechanistic studies, we created an optical technique, TEMPO, that records the aggregate trans-membrane voltage dynamics of genetically specified neurons in freely behaving mice. TEMPO has >10-fold greater sensitivity than prior fiber-optic techniques and attains the noise minimum set by quantum mechanical photon shot noise. After validating TEMPO's capacity to track established oscillations in the delta, theta, and gamma frequency bands, we compared the D1- and D2-dopamine-receptor-expressing striatal medium spiny neurons (MSNs), which are interspersed and electrically indistinguishable. Unexpectedly, MSN population dynamics exhibited two distinct coherent states that were commonly indiscernible in electrical recordings and involved synchronized hyperpolarizations across both MSN subtypes. Overall, TEMPO allows the deconstruction of normal and pathologic neurophysiological states into trans-membrane voltage activity patterns of specific cell types.


Subject(s)
Brain Waves , Mice/physiology , Neurophysiology/methods , Voltage-Sensitive Dye Imaging/methods , Animals , Female , Male , Mice, Inbred BALB C
6.
Mol Cell ; 83(21): 3869-3884.e7, 2023 Nov 02.
Article in English | MEDLINE | ID: mdl-37797622

ABSTRACT

Effective immunity requires the innate immune system to distinguish foreign nucleic acids from cellular ones. Cellular double-stranded RNAs (dsRNAs) are edited by the RNA-editing enzyme ADAR1 to evade being recognized as viral dsRNA by cytoplasmic dsRNA sensors, including MDA5 and PKR. The loss of ADAR1-mediated RNA editing of cellular dsRNA activates MDA5. Additional RNA-editing-independent functions of ADAR1 have been proposed, but a specific mechanism has not been delineated. We now demonstrate that the loss of ADAR1-mediated RNA editing specifically activates MDA5, whereas loss of the cytoplasmic ADAR1p150 isoform or its dsRNA-binding activity enabled PKR activation. Deleting both MDA5 and PKR resulted in complete rescue of the embryonic lethality of Adar1p150-/- mice to adulthood, contrasting with the limited or no rescue by removing MDA5 or PKR alone. Our findings demonstrate that MDA5 and PKR are the primary in vivo effectors of fatal autoinflammation following the loss of ADAR1p150.


Subject(s)
Immunity, Innate , RNA, Double-Stranded , Animals , Mice , Adenosine Deaminase/genetics , Adenosine Deaminase/metabolism , Cytoplasm/metabolism , Immunity, Innate/genetics , RNA, Double-Stranded/genetics
7.
Genes Dev ; 36(15-16): 916-935, 2022 08 01.
Article in English | MEDLINE | ID: mdl-36175033

ABSTRACT

Alternative polyadenylation (APA) generates transcript isoforms that differ in the position of the 3' cleavage site, resulting in the production of mRNA isoforms with different length 3' UTRs. Although widespread, the role of APA in the biology of cells, tissues, and organisms has been controversial. We identified >500 Drosophila genes that express mRNA isoforms with a long 3' UTR in proliferating spermatogonia but a short 3' UTR in differentiating spermatocytes due to APA. We show that the stage-specific choice of the 3' end cleavage site can be regulated by the arrangement of a canonical polyadenylation signal (PAS) near the distal cleavage site but a variant or no recognizable PAS near the proximal cleavage site. The emergence of transcripts with shorter 3' UTRs in differentiating cells correlated with changes in expression of the encoded proteins, either from off in spermatogonia to on in spermatocytes or vice versa. Polysome gradient fractionation revealed >250 genes where the long 3' UTR versus short 3' UTR mRNA isoforms migrated differently, consistent with dramatic stage-specific changes in translation state. Thus, the developmentally regulated choice of an alternative site at which to make the 3' end cut that terminates nascent transcripts can profoundly affect the suite of proteins expressed as cells advance through sequential steps in a differentiation lineage.


Subject(s)
Adult Stem Cells , RNA Isoforms , 3' Untranslated Regions/genetics , Adult Stem Cells/metabolism , Animals , Male , Polyadenylation , Protein Isoforms/genetics , RNA Isoforms/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism
8.
Nature ; 608(7923): 569-577, 2022 08.
Article in English | MEDLINE | ID: mdl-35922514

ABSTRACT

A major challenge in human genetics is to identify the molecular mechanisms of trait-associated and disease-associated variants. To achieve this, quantitative trait locus (QTL) mapping of genetic variants with intermediate molecular phenotypes such as gene expression and splicing have been widely adopted1,2. However, despite successes, the molecular basis for a considerable fraction of trait-associated and disease-associated variants remains unclear3,4. Here we show that ADAR-mediated adenosine-to-inosine RNA editing, a post-transcriptional event vital for suppressing cellular double-stranded RNA (dsRNA)-mediated innate immune interferon responses5-11, is an important potential mechanism underlying genetic variants associated with common inflammatory diseases. We identified and characterized 30,319 cis-RNA editing QTLs (edQTLs) across 49 human tissues. These edQTLs were significantly enriched in genome-wide association study signals for autoimmune and immune-mediated diseases. Colocalization analysis of edQTLs with disease risk loci further pinpointed key, putatively immunogenic dsRNAs formed by expected inverted repeat Alu elements as well as unexpected, highly over-represented cis-natural antisense transcripts. Furthermore, inflammatory disease risk variants, in aggregate, were associated with reduced editing of nearby dsRNAs and induced interferon responses in inflammatory diseases. This unique directional effect agrees with the established mechanism that lack of RNA editing by ADAR1 leads to the specific activation of the dsRNA sensor MDA5 and subsequent interferon responses and inflammation7-9. Our findings implicate cellular dsRNA editing and sensing as a previously underappreciated mechanism of common inflammatory diseases.


Subject(s)
Adenosine Deaminase , Genetic Predisposition to Disease , Immune System Diseases , Inflammation , RNA Editing , RNA, Double-Stranded , Adenosine/metabolism , Adenosine Deaminase/genetics , Adenosine Deaminase/metabolism , Alu Elements/genetics , Autoimmune Diseases/genetics , Autoimmune Diseases/immunology , Autoimmune Diseases/pathology , Genome-Wide Association Study , Humans , Immune System Diseases/genetics , Immune System Diseases/immunology , Immune System Diseases/pathology , Immunity, Innate , Inflammation/genetics , Inflammation/immunology , Inflammation/pathology , Inosine/metabolism , Interferon-Induced Helicase, IFIH1/metabolism , Interferons/genetics , Interferons/immunology , Quantitative Trait Loci/genetics , RNA Editing/genetics , RNA, Double-Stranded/genetics , RNA-Binding Proteins/metabolism
9.
EMBO J ; 42(8): e112387, 2023 04 17.
Article in English | MEDLINE | ID: mdl-36872914

ABSTRACT

The cGAS-STING pathway plays an important role in host defense by sensing pathogen DNA, inducing type I IFNs, and initiating autophagy. However, the molecular mechanism of autophagosome formation in cGAS-STING pathway-induced autophagy is still unclear. Here, we report that STING directly interacts with WIPI2, which is the key protein for LC3 lipidation in autophagy. Binding to WIPI2 is necessary for STING-induced autophagosome formation but does not affect STING activation and intracellular trafficking. In addition, the specific interaction between STING and the PI3P-binding motif of WIPI2 leads to the competition of WIPI2 binding between STING and PI3P, and mutual inhibition between STING-induced autophagy and canonical PI3P-dependent autophagy. Furthermore, we show that the STING-WIPI2 interaction is required for the clearance of cytoplasmic DNA and the attenuation of cGAS-STING signaling. Thus, the direct interaction between STING and WIPI2 enables STING to bypass the canonical upstream machinery to induce LC3 lipidation and autophagosome formation.


Subject(s)
Autophagosomes , Autophagy , Membrane Proteins , Autophagosomes/metabolism , Autophagy/physiology , DNA/metabolism , Membrane Proteins/genetics , Membrane Proteins/metabolism , Nucleotidyltransferases/metabolism , Humans
10.
Nature ; 600(7887): 54-58, 2021 12.
Article in English | MEDLINE | ID: mdl-34666338

ABSTRACT

The Moon has a magmatic and thermal history that is distinct from that of the terrestrial planets1. Radioisotope dating of lunar samples suggests that most lunar basaltic magmatism ceased by around 2.9-2.8 billion years ago (Ga)2,3, although younger basalts between 3 Ga and 1 Ga have been suggested by crater-counting chronology, which has large uncertainties owing to the lack of returned samples for calibration4,5. Here we report a precise lead-lead age of 2,030 ± 4 million years ago for basalt clasts returned by the Chang'e-5 mission, and a 238U/204Pb ratio (µ value)6 of about 680 for a source that evolved through two stages of differentiation. This is the youngest crystallization age reported so far for lunar basalts by radiometric dating, extending the duration of lunar volcanism by approximately 800-900 million years. The µ value of the Chang'e-5 basalt mantle source is within the range of low-titanium and high-titanium basalts from Apollo sites (µ value of about 300-1,000), but notably lower than those of potassium, rare-earth elements and phosphorus (KREEP) and high-aluminium basalts7 (µ value of about 2,600-3,700), indicating that the Chang'e-5 basalts were produced by melting of a KREEP-poor source. This age provides a pivotal calibration point for crater-counting chronology in the inner Solar System and provides insight on the volcanic and thermal history of the Moon.

12.
Proc Natl Acad Sci U S A ; 121(15): e2317769121, 2024 Apr 09.
Article in English | MEDLINE | ID: mdl-38564633

ABSTRACT

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by social and communication deficits and repetitive behaviors. The genetic heterogeneity of ASD presents a challenge to the development of an effective treatment targeting the underlying molecular defects. ASD gating charge mutations in the KCNQ/KV7 potassium channel cause gating pore currents (Igp) and impair action potential (AP) firing of dopaminergic neurons in brain slices. Here, we investigated ASD gating charge mutations of the voltage-gated SCN2A/NaV1.2 brain sodium channel, which ranked high among the ion channel genes with mutations in individuals with ASD. Our results show that ASD mutations in the gating charges R2 in Domain-II (R853Q), and R1 (R1626Q) and R2 (R1629H) in Domain-IV of NaV1.2 caused Igp in the resting state of ~0.1% of the amplitude of central pore current. The R1626Q mutant also caused significant changes in the voltage dependence of fast inactivation, and the R1629H mutant conducted proton-selective Igp. These potentially pathogenic Igp were exacerbated by the absence of the extracellular Mg2+ and Ca2+. In silico simulation of the effects of these mutations in a conductance-based single-compartment cortical neuron model suggests that the inward Igp reduces the time to peak for the first AP in a train, increases AP rates during a train of stimuli, and reduces the interstimulus interval between consecutive APs, consistent with increased neural excitability and altered input/output relationships. Understanding this common pathophysiological mechanism among different voltage-gated ion channels at the circuit level will give insights into the underlying mechanisms of ASD.


Subject(s)
Autism Spectrum Disorder , Autistic Disorder , Voltage-Gated Sodium Channels , Humans , Autism Spectrum Disorder/genetics , Autistic Disorder/genetics , Brain , Mutation
13.
Hum Mol Genet ; 33(10): 905-918, 2024 May 04.
Article in English | MEDLINE | ID: mdl-38449065

ABSTRACT

Mutations in AIFM1, encoding for apoptosis-inducing factor (AIF), cause AUNX1, an X-linked neurologic disorder with late-onset auditory neuropathy (AN) and peripheral neuropathy. Despite significant research on AIF, there are limited animal models with the disrupted AIFM1 representing the corresponding phenotype of human AUNX1, characterized by late-onset hearing loss and impaired auditory pathways. Here, we generated an Aifm1 p.R450Q knock-in mouse model (KI) based on the human AIFM1 p.R451Q mutation. Hemizygote KI male mice exhibited progressive hearing loss from P30 onward, with greater severity at P60 and stabilization until P210. Additionally, muscle atrophy was observed at P210. These phenotypic changes were accompanied by a gradual reduction in the number of spiral ganglion neuron cells (SGNs) at P30 and ribbons at P60, which coincided with the translocation of AIF into the nucleus starting from P21 and P30, respectively. The SGNs of KI mice at P210 displayed loss of cytomembrane integrity, abnormal nuclear morphology, and dendritic and axonal demyelination. Furthermore, the inner hair cells and myelin sheath displayed abnormal mitochondrial morphology, while fibroblasts from KI mice showed impaired mitochondrial function. In conclusion, we successfully generated a mouse model recapitulating AUNX1. Our findings indicate that disruption of Aifm1 induced the nuclear translocation of AIF, resulting in the impairment in the auditory pathway.


Subject(s)
Apoptosis Inducing Factor , Disease Models, Animal , Hearing Loss , Animals , Humans , Male , Mice , Apoptosis Inducing Factor/genetics , Apoptosis Inducing Factor/metabolism , Cell Nucleus/metabolism , Cell Nucleus/genetics , Gene Knock-In Techniques , Hair Cells, Auditory, Inner/metabolism , Hair Cells, Auditory, Inner/pathology , Hearing Loss/genetics , Hearing Loss/pathology , Hearing Loss/metabolism , Muscular Atrophy/genetics , Muscular Atrophy/pathology , Muscular Atrophy/metabolism , Mutation , Protein Transport , Spiral Ganglion/metabolism , Spiral Ganglion/pathology
14.
RNA ; 30(5): 500-511, 2024 Apr 16.
Article in English | MEDLINE | ID: mdl-38531645

ABSTRACT

Innate immunity must be tightly regulated to enable sensitive pathogen detection while averting autoimmunity triggered by pathogen-like host molecules. A hallmark of viral infection, double-stranded RNAs (dsRNAs) are also abundantly encoded in mammalian genomes, necessitating surveillance mechanisms to distinguish "self" from "nonself." ADAR1, an RNA editing enzyme, has emerged as an essential safeguard against dsRNA-induced autoimmunity. By converting adenosines to inosines (A-to-I) in long dsRNAs, ADAR1 covalently marks endogenous dsRNAs, thereby blocking the activation of the cytoplasmic dsRNA sensor MDA5. Moreover, beyond its editing function, ADAR1 binding to dsRNA impedes the activation of innate immune sensors PKR and ZBP1. Recent landmark studies underscore the utility of silencing ADAR1 for cancer immunotherapy, by exploiting the ADAR1-dependence developed by certain tumors to unleash an antitumor immune response. In this perspective, we summarize the genetic and mechanistic evidence for ADAR1's multipronged role in suppressing dsRNA-mediated autoimmunity and explore the evolving roles of ADAR1 as an immuno-oncology target.


Subject(s)
Adenosine Deaminase , RNA Editing , Animals , Adenosine Deaminase/metabolism , Immunity, Innate/genetics , Interferon-Induced Helicase, IFIH1/genetics , Mammals/genetics , RNA, Double-Stranded/genetics , Humans
15.
Mol Cell ; 69(2): 279-291.e5, 2018 01 18.
Article in English | MEDLINE | ID: mdl-29351847

ABSTRACT

Sustained energy starvation leads to activation of AMP-activated protein kinase (AMPK), which coordinates energy status with numerous cellular processes including metabolism, protein synthesis, and autophagy. Here, we report that AMPK phosphorylates the histone methyltransferase EZH2 at T311 to disrupt the interaction between EZH2 and SUZ12, another core component of the polycomb repressive complex 2 (PRC2), leading to attenuated PRC2-dependent methylation of histone H3 at Lys27. As such, PRC2 target genes, many of which are known tumor suppressors, were upregulated upon T311-EZH2 phosphorylation, which suppressed tumor cell growth both in cell culture and mouse xenografts. Pathologically, immunohistochemical analyses uncovered a positive correlation between AMPK activity and pT311-EZH2, and higher pT311-EZH2 correlates with better survival in both ovarian and breast cancer patients. Our finding suggests that AMPK agonists might be promising sensitizers for EZH2-targeting cancer therapies.


Subject(s)
AMP-Activated Protein Kinases/metabolism , Enhancer of Zeste Homolog 2 Protein/metabolism , Animals , Carcinogenesis/genetics , Cell Cycle , Cell Line, Tumor , Cell Proliferation , DNA Methylation , DNA-Binding Proteins/metabolism , Enhancer of Zeste Homolog 2 Protein/genetics , Enhancer of Zeste Homolog 2 Protein/physiology , Epigenesis, Genetic , Female , Histones/metabolism , Humans , Mice , Neoplasm Proteins , Nuclear Proteins/metabolism , Oncogenes , Ovarian Neoplasms/metabolism , Phosphorylation , Polycomb Repressive Complex 2/metabolism , Polycomb Repressive Complex 2/physiology , Transcription Factors , Up-Regulation
16.
Proc Natl Acad Sci U S A ; 120(39): e2307722120, 2023 09 26.
Article in English | MEDLINE | ID: mdl-37725654

ABSTRACT

Single-cell RNA-seq (scRNA-seq) analysis of multiple samples separately can be costly and lead to batch effects. Exogenous barcodes or genome-wide RNA mutations can be used to demultiplex pooled scRNA-seq data, but they are experimentally or computationally challenging and limited in scope. Mitochondrial genomes are small but diverse, providing concise genotype information. We developed "mitoSplitter," an algorithm that demultiplexes samples using mitochondrial RNA (mtRNA) variants, and demonstrated that mtRNA variants can be used to demultiplex large-scale scRNA-seq data. Using affordable computational resources, mitoSplitter can accurately analyze 10 samples and 60,000 cells in 6 h. To avoid the batch effects from separated experiments, we applied mitoSplitter to analyze the responses of five non-small cell lung cancer cell lines to BET (Bromodomain and extraterminal) chemical degradation in a multiplexed fashion. We found the synthetic lethality of TOP2A inhibition and BET chemical degradation in BET inhibitor-resistant cells. The result indicates that mitoSplitter can accelerate the application of scRNA-seq assays in biomedical research.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Humans , RNA, Mitochondrial , Single-Cell Gene Expression Analysis , Mitochondria/genetics
17.
J Neurosci ; 44(4)2024 Jan 24.
Article in English | MEDLINE | ID: mdl-38050110

ABSTRACT

Working memory (WM) maintenance relies on multiple brain regions and inter-regional communications. The hippocampus and entorhinal cortex (EC) are thought to support this operation. Besides, EC is the main gateway for information between the hippocampus and neocortex. However, the circuit-level mechanism of this interaction during WM maintenance remains unclear in humans. To address these questions, we recorded the intracranial electroencephalography from the hippocampus and EC while patients (N = 13, six females) performed WM tasks. We found that WM maintenance was accompanied by enhanced theta/alpha band (2-12 Hz) phase synchronization between the hippocampus to the EC. The Granger causality and phase slope index analyses consistently showed that WM maintenance was associated with theta/alpha band-coordinated unidirectional influence from the hippocampus to the EC. Besides, this unidirectional inter-regional communication increased with WM load and predicted WM load during memory maintenance. These findings demonstrate that WM maintenance in humans engages the hippocampal-entorhinal circuit, with the hippocampus influencing the EC in a load-dependent manner.


Subject(s)
Hippocampus , Memory, Short-Term , Female , Humans , Brain , Electrocorticography , Entorhinal Cortex , Electroencephalography , Theta Rhythm
18.
J Biol Chem ; 300(9): 107656, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39128715

ABSTRACT

Adrenergic modulation of voltage gated Ca2+ currents is a context specific process. In the heart Cav1.2 channels initiate excitation-contraction coupling. This requires PKA phosphorylation of the small GTPase Rad (Ras associated with diabetes) and involves direct phosphorylation of the Cav1.2 α1 subunit at Ser1700. A contributing factor is the proximity of PKA to the channel through association with A-kinase anchoring proteins (AKAPs). Disruption of PKA anchoring by the disruptor peptide AKAP-IS prevents upregulation of Cav1.2 currents in tsA-201 cells. Biochemical analyses demonstrate that Rad does not function as an AKAP. Electrophysiological recording shows that channel mutants lacking phosphorylation sites (Cav1.2 STAA) lose responsivity to the second messenger cAMP. Measurements in cardiomyocytes isolated from Rad-/- mice show that adrenergic activation of Cav1.2 is attenuated but not completely abolished. Whole animal electrocardiography studies reveal that cardiac selective Rad KO mice exhibited higher baseline left ventricular ejection fraction, greater fractional shortening, and increased heart rate as compared to control animals. Yet, each parameter of cardiac function was slightly elevated when Rad-/- mice were treated with the adrenergic agonist isoproterenol. Thus, phosphorylation of Cav1.2 and dissociation of phospho-Rad from the channel are local cAMP responsive events that act in concert to enhance L-type calcium currents. This convergence of local PKA regulatory events at the cardiac L-type calcium channel may permit maximal ß-adrenergic influence on the fight-or-flight response.


Subject(s)
Calcium Channels, L-Type , Cyclic AMP-Dependent Protein Kinases , Mice, Knockout , Myocytes, Cardiac , Animals , Calcium Channels, L-Type/metabolism , Calcium Channels, L-Type/genetics , Cyclic AMP-Dependent Protein Kinases/metabolism , Cyclic AMP-Dependent Protein Kinases/genetics , Phosphorylation , Mice , Myocytes, Cardiac/metabolism , Humans , Cyclic AMP/metabolism , A Kinase Anchor Proteins/metabolism , A Kinase Anchor Proteins/genetics , Isoproterenol/pharmacology , ras Proteins
19.
Circulation ; 2024 Sep 24.
Article in English | MEDLINE | ID: mdl-39315453

ABSTRACT

BACKGROUND: Short-coupled ventricular fibrillation (SCVF) is increasingly being recognized as a distinct primary electrical disorder and cause of otherwise unexplained cardiac arrest. However, the pathophysiology of SCVF remains largely elusive. Despite extensive genetic screening, there is no convincing evidence of a robust monogenic disease gene, thus raising the speculations for alternative pathogeneses. The role of autoimmune mechanisms in SCVF has not been investigated so far. The objective of this study was to screen for circulating autoantibodies in patients with SCVF and assess their role in arrhythmogenesis. METHODS: This is a prospective, single-center, case-control study enrolling cardiac arrest survivors diagnosed with SCVF or idiopathic ventricular fibrillation (IVF) between 2019 and 2023 at the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval Inherited Arrhythmia Clinic in Canada. Plasma samples were screened for autoantibodies targeting cardiac ion channels using peptide microarray technology. Identified target autoantibodies were then purified from pooled plasma samples for subsequent cellular electrophysiological studies. RESULTS: Fourteen patients with SCVF (n=4 [29% of patients] female patients; median age, 45 years [interquartile range: 36, 59]; n=14 [100% of patients] non-Hispanic White) and 19 patients with idiopathic ventricular fibrillation (n=8 [42%] female patients; median age, 49 years [38, 57]; n=19 [100%] non-Hispanic White) were enrolled in the study and compared with 38 (n=20 [53%] female subjects; median age, 45 years [29, 66]; n=36 [95%] non-Hispanic White) sex-, age- and ethnicity-matched healthy controls. During the study period, 11 (79%) SCVF probands experienced ventricular fibrillation recurrence after a median of 4.3 months (interquartile range, 0.3-20.7). Autoantibodies targeting cardiac TREK-1 (TWIK [tandem of pore-domains in a weakly inward rectifying potassium channel]-related potassium channel 1 were identified in 7 (50%) patients with SCVF (P=0.049). Patch clamp experiments demonstrated channel-activating properties of anti-TREK-1 autoantibodies that are antagonized by quinidine in both HEK293 cells and human induced pluripotent stem cell-derived cardiomyocytes. CONCLUSIONS: Patients with SCVF harbor circulating autoantibodies against the cardiac TREK-1 channel. Anti-TREK-1 autoantibodies not only present the first reported biomarker for SCVF, but our functional studies also suggest a direct implication in the arrhythmogenesis of SCVF.

20.
J Virol ; 98(1): e0155823, 2024 Jan 23.
Article in English | MEDLINE | ID: mdl-38174926

ABSTRACT

Enterovirus A71 (EV-A71) can induce severe neurological complications and even fatal encephalitis in children, and it has caused several large outbreaks in Taiwan since 1998. We previously generated VP1 codon-deoptimized (VP1-CD) reverse genetics (rg) EV-A71 viruses (rgEV-A71s) that harbor a high-fidelity (HF) 3D polymerase. These VP1-CD-HF rgEV-A71s showed lower replication kinetics in vitro and decreased virulence in an Institute of Cancer Research (ICR) mouse model of EV-A71 infection, while still retaining their antigenicity in comparison to the wild-type virus. In this study, we aimed to further investigate the humoral and cellular immune responses elicited by VP1-CD-HF rgEV-A71s to assess the potential efficacy of these EV-A71 vaccine candidates. Following intraperitoneal (i.p.) injection of VP1-CD-HF rgEV-A71s in mice, we observed a robust induction of EV-A71-specific neutralizing IgG antibodies in the antisera after 21 days. Splenocytes isolated from VP1-CD-HF rgEV-A71s-immunized mice exhibited enhanced proliferative activities and cytokine production (IL-2, IFN-γ, IL-4, IL-6, and TNF-α) upon re-stimulation with VP1-CD-HF rgEV-A71, as compared to control mice treated with adjuvant only. Importantly, administration of antisera from VP1-CD-HF rgEV-A71s-immunized mice protected against lethal EV-A71 challenge in neonatal mice. These findings highlight that our generated VP1-CD-HF rgEV-A71 viruses are capable of inducing both cellular and humoral immune responses, supporting their potential as next-generation EV-A71 vaccines for combating EV-A71 infection.IMPORTANCEEV-A71 can cause severe neurological diseases and cause death in young children. Here, we report the development of synthetic rgEV-A71s with the combination of codon deoptimization and high-fidelity (HF) substitutions that generate genetically stable reverse genetics (rg) viruses as potential attenuated vaccine candidates. Our work provides insight into the development of low-virulence candidate vaccines through a series of viral genetic editing for maintaining antigenicity and genome stability and suggests a strategy for the development of an innovative next-generation vaccine against EV-A71.


Subject(s)
Capsid Proteins , Enterovirus A, Human , Enterovirus Infections , RNA-Dependent RNA Polymerase , Animals , Mice , Antibodies, Viral/immunology , Codon , Enterovirus A, Human/genetics , Enterovirus Infections/immunology , Vaccines, Attenuated , Capsid Proteins/genetics , Immunity, Humoral , Immunity, Cellular , Antibodies, Neutralizing/immunology , Viral Vaccines , Mice, Inbred ICR , Mice, Inbred BALB C , RNA-Dependent RNA Polymerase/genetics
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