Biology subjects

Xiong, W.

Publications and source records attributed to Xiong, W..

At least 19 recordsLinked to original sources

bioRxiv2026

Synergistic Inhibition of Notch Signaling and Forced Cell Cycle Re-entry Drive Müller Glia Reprogramming in Uninjured Mouse Retina

In regenerative species, such as teleost fish, Muller glia (MG) autonomously re-enter the cell cycle after injury and give rise to functional retinal neurons. In contrast, the loss of retinal neurons in mammals is irreversible due to the limited proliferative and regenerative ability of MG. Various strategies have been developed to induce proliferation of mature mouse MG with or without injury, yet most MG daughter cells retain glial cell fate. Here, we found that MG progenies maintain high Notch signaling, which may constrain their neurogenic potential. Conditional deletion of Rbpj, the central transcriptional effector of Notch, induced limited MG-to-neuron conversion in mature MG without proliferation. However, Rbpj deletion, combined with forced MG proliferation by overexpressing cyclin D1 and suppressing p27Kip1, significantly promoted MG dedifferentiation and ectopic expression of the neuronal marker Otx2 in MG daughter cells in uninjured mouse retina. Combining Notch inhibition with MG cell cycle re-activation not only increased the numbers of bipolar- and amacrine-like cells generated from MG but also promoted the further differentiation toward ON-cone, OFF-cone, and rod-bipolar subtypes. Single-nucleus RNA and ATAC sequencing data revealed that Notch inhibition facilitated the formation of MG-derived progenitor-like cells while MG proliferation increased chromatin accessibility of neurogenic genes. Notably, most MG-derived cells survived long term despite incomplete maturation. Together, our findings delineate how Notch inhibition and MG proliferation, alone or in combination, influence the regenerative potential of MG in the mammalian retina.

cell biology↗

bioRxiv2025

Gasdermin E couples mitochondrial damage to pyroptotic neurodegeneration in Parkinson disease

Parkinsons disease (PD) features progressive loss of nigrostriatal dopamine neurons, but how mitochondrial damage engages programmed cell death pathways remains unresolved. Here, we identify gasdermin E (GSDME), the caspase-3-activated executor of pyroptosis, as a critical mediator of neurodegeneration in toxin-based PD models. In primary neurons and SH-SY5Y cells, the mitochondrial complex I inhibitor MPTP/MPP triggered caspase-3 activation, GSDME cleavage, and lytic membrane rupture. Genetic silencing of Gsdme or its transcriptional regulator SP1 reduced neuronal death. In vivo, Gsdme deficiency preserved substantia nigra pars compacta dopaminergic neurons, improved motor performance, and mitigated anxiety- and depression-like behaviors after MPTP administration. Loss of Gsdme also dampened microglial and astrocytic activation and lowered proinflammatory cytokines in striatum and substantia nigra. Mechanistically, cleaved GSDME localized to mitochondria, disrupted membrane potential, increased reactive oxygen species, and precipitated organelle injury, thereby coupling mitochondrial dysfunction to pyroptotic cell death. These findings identify GSDME-mediated pyroptosis as a mechanistic link between mitochondrial toxicity and neuroinflammation in PD and nominate GSDME as a therapeutic entry point to slow disease progression. SignificanceHow mitochondrial injury kills dopamine neurons in Parkinsons disease is a central unresolved question. We show that the pyroptosis executor GSDME is required for neurodegeneration and neuroinflammation in MPTP models, mechanistically linking caspase-3 activation and mitochondrial damage to lytic cell death. Targeting GSDME may provide a strategy to protect vulnerable neurons in PD. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=191 SRC="FIGDIR/small/694264v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@15364e7org.highwire.dtl.DTLVardef@57b65org.highwire.dtl.DTLVardef@1e85108org.highwire.dtl.DTLVardef@1200d34_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsGSDME drives PD-linked neuronal loss. Silencing GSDME (or its transcriptional factor Sp1) ameliorates MPTP-triggered neuronal cell death. Genetic ablation of Gsdme is protective in the MPTP-induced PD mouse model. Gsdme-/-mice retain nigrostriatal DA neurons, show improved motor and affective behaviors, and exhibit reduced microglial and astrocytic activation and cytokines release upon MPTP treatment. Cleaved GSDME accumulates on mitochondria, collapses {Delta}{Psi}m, raises ROS, and links mitochondrial toxicity to pyroptosis, thus positioning GSDME as a tractable target to slow PD progression.

neuroscience↗

bioRxiv2025

Early blood-spinal cord barrier stabilization preserves peri-lesional tissue and improves recovery after SCI

Vascular disruption is an early and critical event in spinal cord injury (SCI), but its contribution remains poorly understood. Using novel in vivo two-photon dual-dye imaging, we found simultaneous blood-spinal cord barrier (BSCB) leakage and venous dilation in both the injury epicenter and adjacent transitional segment after cervical SCI in rats. Notably, vascular permeability in the transitional zone preceded axonal and neuronal loss, revealing a therapeutic window. Systemic delivery of ferulic acid-glycol chitosan (FA-GC) nanoparticles, a membrane-sealant, rapidly stabilized the compromised vasculature, reduced neuronal loss in the transitional region, and improved forelimb muscle strength. These findings identified acute vascular leakage beyond the injury epicenter as a driver of secondary pathology and highlight early vascular stabilization as promising therapeutic strategy.

pathology↗

bioRxiv2025

Structural and functional insights into QueC-family protein in QatABCD anti-phage system

QatABCD is a widespread prokaryotic anti-phage defense system comprising four protein components, out of which QatC, a QueC-family protein is the signature component. QueC family proteins are nucleoside biosynthesis enzymes involved in the biosynthesis of queuosine, a 7-deazaguanine derivative. Recently, QueC-family proteins were shown to catalyze a deazaguanylation protein-nucleobase conjugation reaction in type IV CBASS antiphage defense. However, the mechanism of QatABCD, even the function of QatC in this system, remains unknown. Here, we demonstrate that QatBCD forms a complex in which QatD is highly flexible. Crystal structures of the QatBC complex in apo and ATP-bound form support a shared role for QueC-family proteins in targeting protein substrates for N-terminal modification as in type IV CBASS. We show that the QatB N-terminal loop, its binding with QatC and QatC catalytic site are essential for QatABCD defense in vivo, suggesting a modification might occur analogous to CBASS. These findings provide structural and functional insights into QueC-family protein in QatABCD system, suggesting the conserved mechanisms and critical roles of QueC-family in prokaryotic immunity.

biochemistry↗

bioRxiv2025

Structural insights into type I and type II Lamassu anti-phage systems

Bacteria have developed a variety of immune systems to combat phage infections. The Lamassu system is a prokaryotic immune system with a core conserved Structural Maintenance of Chromosomes (SMC) superfamily protein LmuB and diverse effectors named LmuA, whose mechanism remains unclear. Here, we present a series of cryo-electron microscopy structures of type I Lamassu complex from Bacillus cellulasensis and type II Lamassu complex from Vibrio cholerae, both in apo- and dsDNA-bound states, which reveal an unexpected stoichiometry and topological architecture, distinct from canonical SMC complexes. Combined structural and biochemical analyses show how the nuclease effector LmuA is sequestered in an inactive monomeric form within the Lamassu complex, and upon sensing foreign DNA ends, dissociates and assembles into an active tetramer capable of DNA cleavage. Our findings elucidate the mechanism by which Lamassu systems detect viral replication and implement anti-phage defense, highlighting the unprecedented roles of SMC proteins in prokaryotic immunity.

microbiology↗

bioRxiv2025

FSCN1-Mediated Hepatic Gluconeogenesis Is Indispensable for Neonatal Mice Survival

Actin-Bundling Protein Fascin1 (FSCN1) is encoded by the Fscn1 gene, and crucial for cytoskeletal remodeling and cellular migration. While previous study linked Fscn1 deficiency to neonatal lethality in mice, the underlying metabolic mechanism remains unexplored. Here, in this study, we report that systemic knockout (KO) of Fscn1 leads to 52.2% mortality within 24 hours post-birth, accompanied by severe hypoglycemia in KO pups compared to other littermates. Remarkably, this lethality was fully rescued by oral glucose administration, indicating a glucose supply-dependent survival mechanism. Surviving Fscn1 KO neonates displayed persistent developmental deficits, including growth retardation and depleted lipid stores, despite intact canonical insulin-regulated hepatic gluconeogenic pathways. Transcriptomic profiling of P0 livers revealed that Fscn1 loss predominantly disrupts metabolic pathway, within the glycerol phosphate shuttle being the most significantly downregulated module. Mechanistically, Fscn1 KO livers exhibited markedly reduced protein levels of glycerol-3-phosphate dehydrogenase isoforms (GPD1/GPD2), key enzymes bridging glycolysis and gluconeogenesis. Consistently, glycerol tolerance tests (GTT) demonstrated impaired glycerol-to-glucose conversion in Fscn1 KO mice, confirming defective glycerol-driven gluconeogenesis. Our findings establish FSCN1 as a novel cytoskeletal-metabolic integrator essential for neonatal survival by sustaining hepatic glucose production from glycerol, thus revealing an unexpected role of actin dynamics in coordinating metabolic adaptation during early postnatal development. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=184 HEIGHT=200 SRC="FIGDIR/small/654691v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@b4fb56org.highwire.dtl.DTLVardef@1e0f47forg.highwire.dtl.DTLVardef@1d3cb1eorg.highwire.dtl.DTLVardef@1bc6022_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIFSCN1 deficiency triggers hypoglycemia-driven neonatal mortality by disrupting hepatic glucose production. C_LIO_LIFscn1 loss impairs the gluconeogenesis via suppressing GPD1/GPD2 expression, while sparing insulin-regulated gluconeogenesis. C_LIO_LICytoskeletal dysfunction impairs glycerol-to-glucose conversion, revealing actin-metabolism crosstalk in postnatal adaptation. C_LI

molecular biology↗

bioRxiv2025

Lipid nanoparticle-mediated CRISPR/Cas9 delivery enables efficient trabecular meshwork gene editing in mice

Lipid nanoparticles (LNPs) have emerged as a transformative platform for mRNA delivery, enabling vaccines and gene editing with transient expression and high cargo capacity. However, their potential for ocular gene editing remains underexplored. In this study, we assessed the transduction efficiency, inflammatory response, and gene editing capability of LNP-encapsulated mRNA in murine eyes. Intravitreal delivery of LNPs achieved targeted mRNA expression in the trabecular meshwork (TM) with superior specificity and efficiency compared to adenoviral or adeno-associated viral vectors, while inducing minimal microglial activation in the retina. Using LNPs co-encapsulating SpCas9 mRNA and sgRNA, we demonstrated efficient CRISPR-mediated knockout (KO) of Matrix Gla Protein (Mgp), a key inhibitor of TM calcification. Mgp-KO eyes exhibited sustained intraocular pressure (IOP) elevation and anterior chamber deepening with normal anterior chamber angle, recapitulating key features of primary open-angle glaucoma (POAG). Chronic IOP elevation led to reactive Muller gliosis and ganglion cell complex thinning, reflecting retinal stress and progressive neurodegeneration. Our findings establish LNP-CRISPR as a safe and efficient system for TM-targeted gene editing, with broad applicability in glaucoma pathogenesis modelling and therapeutic discovery.

neuroscience↗

bioRxiv2025

Integrated Classification of Cortical Cells and Quantitative Projectomic Mapping Unveil Organizational Principles of Brain-Wide Connectomes at Single Cell Level

Molecularly defined cortical cell types have recently been linked to whole neuronal morphology (WNM), particularly those characterized by whole-brain-wide projections, such as intratelencephalic (IT), extratelencephalic (ET), and corticothalamic (CT) neurons. In contrast, classical morphological classifications (e.g., tufted TPC, small tufted SPC, and stellate SSC) are based primarily on local dendrosomatic and axonal structures, especially apical dendrites. This study bridges these perspectives by establishing a new neuronal taxonomy, analyzing the connectomes of defined cortical cell types, and comparing them with those obtained from bulk anterograde injections. Neurons were sparsely labeled via tamoxifen-inducible Cre lines with GFP reporters, and 1,419 WNM cells were comprehensively reconstructed with Vaa3D-TeraVR from [~]15 areas across six functional regions of molecularly labeled brains imaged with 2p-fMOST. These cells were newly classified by integrating current molecular-WNM and classical morphological perspectives, with sample size augmented by 1,455 publicly available WNM cells reconstructed from the Mouse-Light project and CEBSIT. This effort defined ten combined molecular-WNM-classical morphological cell types: L5ET_TPC, L6CT_NPC, L6b_HPC, and seven IT types--L2/3IT_TPC, L4IT_SSC, L4IT_UPC, L4IT_TPC, L5IT_SPC, L6IT_IPC, and L6IT_car3PC. Clustering, quantitative analyses and random Forest classifier objectively validated these types and revealed their distinct connectomes, along with convergent, topographic, and hierarchical organizations across their projection brain regions. At the single-cell level, multiple organizational principles governing cortico-cortical (C-C) and cortico-subcortical (C-subC) connectomes emerged with unprecedented detail, offering a precise GPS-like tool for in vivo recordings and robust datasets for neuronal network modeling. Comparisons with bulk anterograde injection data underscored the limitations of traditional methods in identifying projection targets. Overall, our approach provides significant insights into cortical circuitry and elucidates the complex interplay between neuronal molecular identity, whole morphology, and classical morphological classification.

neuroscience↗

bioRxiv2024

A benchmarking study of copy number variation inference methods using single-cell RNA-sequencing data

Single-cell RNA-sequencing (scRNA-seq) has emerged as a powerful tool for cancer research, enabling in-depth characterization of tumor heterogeneity at the single-cell level. Recently, scRNA-seq copy number variation (scCNV) inference methods have been developed, expanding the application of scRNA-seq to study genetic heterogeneity in cancer using transcriptomic data. However, the fidelity of these methods has not been investigated systematically. In this study, we benchmarked five commonly used scCNV inference methods, HoneyBADGER, CopyKAT, CaSpER, inferCNV, and sciCNV. We evaluated their performance across four different scRNA-seq platforms derived data from a multicenter study. We further evaluated the scCNV performance using scRNA-seq datasets derived from mixed samples consisting of five human lung adenocarcinoma cell lines and generated a clinical scRNA-seq dataset from a human small cell lung cancer patient to validate our findings. Our evaluation criteria included sensitivity and specificity of CNV detection, and subclone identification from mixed cancer samples. We found that the sensitivity and specificity of the five scCNV inference methods varied, depending on the selection of reference data, sequencing depths, and read lengths. Overall, CopyKAT and CaSpER exhibited superior performance to other methods, while inferCNV, sciCNV, and CopyKAT outperformed other methods in subclone identification accuracy. Remarkably, inferCNV achieved high accuracy in subclone identification when using data from a "single scRNA-seq protocol", however, when applying these methods to a dataset derived from multiple scRNA-seq platforms from the mixed samples, we found that batch effects significantly affected the performance of subclone identification for most methods, except for HoneyBADGER. Our benchmarking study revealed the strengths and weaknesses of each of the five scCNV inference methods and provided guidance for selecting the optimal CNV inference method using scRNA-seq data.

bioinformatics↗

bioRxiv2024

CIB2 as a Ca2+ Sensor for Auditory Mechano-Electrical Transduction and Linked to Genetic-Heterogeneity of TMC1 in Hearing Loss

Non-syndromic sensorineural hearing loss is characterized by genetic heterogeneity, leading to potential clinical misdiagnosis. TMC1, a unique causative gene associated with deafness, exhibits variants with autosomal dominant and recessive inheritance patterns. TMC1 codes for the transmembrane channel-like 1 (TMC1), a key component of the mechano-electrical transduction (MET) machinery for hearing. However, the molecular mechanism of Ca2+ regulation in MET, which is essential for sound perception, remains unclear. CIB2, another MET component associated with deafness, can bind with calcium and may play a role in MET gating. Our study reveals that the TMC1-CIB2 complex undergoes a Ca2+-induced conformational change, highlighting the crucial role of Ca2+ in MET. We identified a vertebrate-specific binding site on TMC1, named CR3, that interacts with apo CIB2, with the binding interface linked to hearing loss. Using an in-vivo animal model, we demonstrated that disruption of the calcium-sensing site of CIB2 perturbs the MET channel conductivity, confirming its role as a Ca2+ sensor for MET. Additionally, after systematically analyzing the hearing-loss variants, we observed that dominant mutations of TMC1 are often located near the ion pore or at the binding interfaces with the Ca2+ sensor CIB2. This provides a detailed mechanism of the genetic heterogeneity of TMC1 in hearing loss at an atomic level.

molecular biology↗

bioRxiv2024

Many erroneous noncoding transcripts in cancer cells can highly specifically regulate cancer-related genes and pathways

Transcription and splicing errors in cancer cells generate erroneous transcripts. Since erroneous transcripts are degraded by the nonsense-mediated mRNA decay (NMD) pathway, whether they are junk or could be functional has been overlooked and understudied. We addressed this question by first performing a pan-cancer analysis and identified substantial erroneous noncoding transcripts (ENT) in cancers. Given that RNA/DNA binding domains (DBD) were predicted in ENTs, we deleted predicted DBDs in multiple ENTs in multiple cell lines, with RNA-sequencing and cell experiments before and after DBD deletion. DBD deletion caused significantly changed expression of ENTs target genes (whose promoter regions contain ENTs DNA binding sites, DBS) and changed cell migration and proliferation ability, indicating that many ENTs can transcriptionally regulate genes. Tightly coupled data analysis and experiments reveal that ENTs functions are highly cancer- and cellular-context specific, making ENTs a new class of safe and specific targets for noncoding RNA-based cancer therapeutics.

genomics↗

bioRxiv2024

Muller glia cell cycle re-activation by simultaneous cyclin D1 overexpression and p27kip1 knockdown promotes retinal regeneration in mice

Harnessing the regenerative potential of endogenous stem cells to restore lost neurons is a promising strategy for treating neurodegenerative disorders. Muller glia (MG), the primary glial cell type in the retina, exhibit extraordinary regenerative abilities in zebrafish, proliferating and differentiating into neurons post-injury. However, the regenerative potential of mouse MG is limited by their inherent inability to re-enter the cell cycle, constrained by high levels of the cell cycle inhibitor p27Kip1 and low levels of cyclin D1. Here, we report a method to drive robust MG proliferation by adeno-associated virus (AAV)-mediated cyclin D1 overexpression and p27Kip1 knockdown. MG proliferation induced by this dual targeting vector was self-limiting, as MG did not undergo uncontrolled proliferation. As shown by single-cell RNA-sequencing, cell cycle reactivation led to suppression of interferon signaling, activation of reactive gliosis, and downregulation of glial genes in MG. Over time, the majority of the MG daughter cells retained the glial fate, resulting in an expanded MG pool. Interestingly, about 1% MG daughter cells expressed markers for retinal interneurons, suggesting latent neurogenic potential in a small MG subset. By establishing a safe, controlled method to promote MG proliferation in vivo while preserving retinal integrity, this work provides a valuable tool for combinatorial therapies integrating neurogenic stimuli to promote neuron regeneration.

neuroscience↗

bioRxiv2024

Intrinsically linked lineage-specificity of transposable elements and lncRNAs reshapes transcriptional regulation species- and tissue-specifically

Unlike protein-coding genes, many mammalian lncRNAs are lineage-specific (LS), but which human and mouse reference lncRNAs are lineage-specific, how they are generated, and whether their regulatory elements are lineage-specific remain unclear. To resolve their origins, properties, and impacts, we systematically classified primate-, simian-, rodent-, human-, and mouse-specific lncRNAs in GENCODE-annotated human and mouse genomes using structure-aware covariance modeling. We predicted their DNA-binding domains (DBDs) and genomic binding sites (DBSs) and traced the origins of embedded transposable elements (TEs). LS TEs contribute to over 84% (human) and 98% (mouse) of LS lncRNAs, 61% and 95% of their DBDs, and 46% and 73% of their DBSs. Analyses of multi-omics data and a developmental process suggest that LS TE-linked lineage-specificity substantially rewires transcriptional regulation and that many evolutionary novelties may be structurally predisposed. These findings bridge the gap between human diseases and mouse models, providing valuable resources for identifying human-specific therapeutic lncRNA targets.

genomics↗

bioRxiv2023

Single phage proteins sequester TIR- and cGAS-generated signaling molecules

Prokaryotic anti-phage immune systems use TIR (toll/interleukin-1 receptor) and cGAS (cyclic GMP-AMP synthase) enzymes to produce 1-3/1-2 glycocyclic ADPR (gcADPR) and cyclid di-/tri-nucleotides (CDNs and CTNs) signaling molecules that limit phage replication, respectively 1-3. However, how phages neutralize these common systems is largely unknown. Here, we show that Thoeris anti-defense proteins Tad1 4 and Tad2 5 both have anti-CBASS activity by simultaneously sequestering CBASS cyclic oligonucleotides. Strikingly, apart from binding Thoeris signals 1-3 and 1-2 gcADPR, Tad1 also binds numerous CBASS CDNs/CTNs with high affinity, inhibiting CBASS systems using these molecules in vivo and in vitro. The hexameric Tad1 has six binding sites for CDNs or gcADPR, which are independent from two high affinity binding sites for CTNs. Tad2 also sequesters various CDNs in addition to gcADPR molecules, inhibiting CBASS systems using these CDNs. However, the binding pockets for CDNs and gcADPR are different in Tad2, whereby a tetramer can bind two CDNs and two gcADPR molecules simultaneously. Taken together, Tad1 and Tad2 are both two-pronged inhibitors that, alongside anti-CBASS protein 2, establish a paradigm of phage proteins that flexibly sequester a remarkable breadth of cyclic nucleotides involved in TIR- and cGAS-based anti-phage immunity.

microbiology↗

bioRxiv2023

The mtDNA-derived lncMtDloop promotes mitochondrial homeostasis maintenance and implications in AD

Maintaining mitochondrial homeostasis stands as a critical factor for cell survival and the health of organisms, as evidenced by the links between mitochondrial dysfunction and a spectrum of diseases, including Alzheimers disease (AD). Here we report that lncMtDloop, a lncRNA originating from the mtDNA D-loop, upholds mitochondrial homeostasis. LncMtDloop demonstrates an affinity for mitochondrial transcription factor A (TFAM), thereby facilitating TFAMs recruitment to mtDNA promoters and enhancing gene transcription. We further observed decreased lncMtDloop expression in the brains of human AD patients and 3xTg mice. Through the introduction of allotropic lncMtDloop with the 3UTR of MRPS12, a significant improvement in mitochondrial homeostasis and a concurrent amelioration of AD-like pathology were found, which exerts a positive influence on synaptic plasticity and behavioral deficits observed in AD mice. Our study provides mechanistic insights into lncMtDloop as a regulator of mitochondrial homeostasis, shedding light on a perspective regarding its contribution to Alzheimers pathogenesis.

molecular biology↗

bioRxiv2023

TFEB degradation is regulated by an IKK/β-TrCP2 phosphorylation-ubiquitination cascade

Transcription factor EB (TFEB) is a master regulator of lysosomal biogenesis and autophagy that plays a key role in the regulation of cellular clearance pathways. TFEB is regulated via a complex array of post-translational modifications (PTMs), but the exact molecular mechanism that regulates TFEB stability has remained elusive. Here, we show that TFEB levels are critically regulated by a defined phosphorylation-ubiquitination cascade. A human kinome screen identifies IKK (inhibitor of {kappa}B kinase) as a TFEB modifier, and a combination of phosphorylation assays, mass spectrometry analyses, and site-specific mutagenesis unveils a previously unrecognized TFEB phospho-degron (423SPFPSLS429) as the target of IKK. We show that IKK-mediated phosphorylation of TFEB triggers ubiquitination of adjacent lysine residues (K430 and K431) by the E3 ligase {beta}-TrCP2 ({beta}-Transducin repeat-containing protein 2), thereby tagging TFEB for degradation. Modified TFEB constructs that abolish these PTMs show much increased stability and expression levels but remain equally sensitive to autophagy- or stress- related stimuli while maintaining the capability to promote the expression of TFEB target genes and the clearance of Alzheimers associated tau in a cellular model of disease. Our results therefore uncover an IKK/{beta}-TrCP2 phosphorylation-ubiquitination cascade as a major mechanism that governs TFEB stability independently of other TFEB regulators.

cell biology↗

bioRxiv2023

PKA catalytic subunits dissociate from regulatory subunits to regulate neuronal functions

Protein kinase A (PKA) plays essential roles in diverse cellular functions. However, the spatiotemporal dynamics of endogenous PKA upon activation remain debated. The classical model predicts that PKA catalytic subunits dissociate from regulatory subunits in the presence of cAMP, whereas a second model proposes that catalytic subunits remain associated with regulatory subunits following physiological activation. Here we report that different PKA subtypes, as defined by the regulatory subunit, exhibit distinct subcellular localization at rest in CA1 neurons of cultured hippocampal slices. Nevertheless, when all tested PKA subtypes are activated by norepinephrine, presumably via the {beta}-adrenergic receptor, catalytic subunits translocate to dendritic spines but regulatory subunits remain unmoved. These differential spatial dynamics between the subunits indicate that at least a significant fraction of PKA dissociates. Furthermore, PKA-dependent regulation of synaptic plasticity and transmission can be supported only by wildtype, dissociable PKA, but not by inseparable PKA. These results indicate that endogenous PKA regulatory and catalytic subunits dissociate to achieve PKA function in neurons.

cell biology↗

bioRxiv2023

Genome assembly and analysis of Lactuca virosa: implications for lettuce breeding

Lettuce (Lactuca sativa L.) is a leafy vegetable crop with ongoing breeding efforts related to quality, resilience, and innovative production systems. Genetic variation of important traits in close relatives is necessary to meet lettuce breeding goals. Lactuca virosa (2x=2n=18), a wild relative assigned to the tertiary lettuce gene pool, has a much larger genome (3.7 Gbp) than Lactuca sativa (2.5 Gbp). It has been used in interspecific crosses and is a donor to modern crisphead lettuce cultivars. Here, we present a de novo reference assembly of L. virosa with high continuity and complete gene space. This assembly facilitated comparisons to the genome of L. sativa and to that of the wild species L. saligna, a representative of the secondary lettuce gene pool. To assess the diversity in gene content, we classified the genes of the three Lactuca species as core, accessory and unique. In addition, we identified three interspecific chromosomal inversions compared to L. sativa, which each may cause recombination suppression and thus hamper future introgression breeding. Using three-way comparisons in both reference-based and reference-free manners, we show that the proliferation of long-terminal repeat elements has driven the genome expansion of L. virosa. Further, we performed a genome-wide comparison of immune genes, nucleotide-binding leucine-rich repeat, and receptor-like kinases among Lactuca spp. and indicate the evolutionary patterns and mechanisms behind their expansions. These genome analyses greatly facilitate the understanding of genetic variation in L. virosa, which is beneficial for the breeding of improved lettuce varieties.

plant biology↗