Biology subjects

Harada, H.

Publications and source records attributed to Harada, H..

17 recordsLinked to original sources

bioRxiv2026

Metformin lowers HMGA1a and RBM3 protein in breast cancer cells, and its effect on ESR1 splicing depends on cell density and exposure time

The ESR1 gene produces ER46, an N-terminally truncated isoform generated by skipping of exon 1, which is reduced in tamoxifen-resistant breast cancer cells. We have reported that metformin moves the ratio of full-length ER to ER46 in opposite directions in MCF-7 cells and their tamoxifen-resistant subline TAMR1, and that metformin reduces TAMR1 xenograft growth (Harada et al., Am J Pharm Health Res 2022;10(11)). That report leaves two questions open: whether the effect is dosedependent and stable across culture conditions, and what splicing factor might carry it. Here we report the experiments that bear on both. Across a full dose range from 0.25 to 5 mM at high seeding density, metformin produced no consistent change in the full-length share of ESR1 transcript in either line: densitometry of the gel gave 42%, 43%, 42%, 43%, 45% and 48% in MCF-7 cells and 55%, 44%, 52%, 47%, 68% and 43% in TAMR1 cells. The reported shift therefore depends on the seeding density used, and the comparison that produced it is not reproduced at high density. At low density the MCF-7 response persisted to 48 h (52%, 62% and 68% at 0, 2.5 and 5 mM). Metformin lowered HMGA1a protein in MCF-7 cells and showed the same tendency in TAMR1 cells, at both seeding densities, and lowered RBM3 protein in TAMR1 cells at 24 and 48 h. HMGA1a is the factor we previously showed to generate ER46 by trapping U1 snRNP at an upstream pseudo-5' splice site, so a fall in HMGA1a predicts less ER46, the opposite of what was seen in TAMR1 cells at low density. The fall in RBM3, the protein through which metformin alters splicing in myotonic dystrophy, is the more plausible candidate. RT-PCR of the xenograft tumours from the earlier study detected full-length ESR1 transcript in the untreated and tamoxifen-plus-metformin groups but not in the singleagent groups, with amplification failing in several lanes; these panels do not separate the treatments. Taken together, the direction of the metformin effect on ESR1 splicing is conditional on culture density and does not survive a dose-response test at high density, and HMGA1a is unlikely to be the factor that carries it.

molecular biology↗

bioRxiv2026

Herboxidiene and EGFR expression in A172 glioblastoma cells

Glioblastoma carries a five-year survival of about 10%, and EGFR amplification is one of the molecular criteria that define the disease in the 2021 WHO classification of central nervous system tumours. SF3b inhibitors, which displace the U2 snRNP from the intron branch point, suppress EGFR expression in lung adenocarcinoma cells by causing retention of EGFR intron 2. We asked whether the same route operates in glioblastoma, using A172 cells, which express wild-type EGFR together with an in-frame tandem duplication of exons 18-26. Herboxidiene inhibited A172 proliferation: DMSO-treated cultures reached 2.32 times their day 0 reading by day 3 (SD 0.61), whereas every herboxidiene concentration from 0.125 to 1 M held the cultures at or below their starting value and differed from the vehicle on days 2 and 3 (Dunnett, p < 0.05). RT-PCR across EGFR exons 2-3 showed no intron 2-retained product at any concentration; instead the spliced product decreased relative to ACTB, to 0.43 of the vehicle value at 0.125 M, without deepening further up to 1 M. EGFR protein fell, but the two forms behaved differently: the 170 kDa wild-type band was no longer detectable from 0.13 M, whereas the 190 kDa duplicated form persisted at every concentration and declined only gradually, to 0.30 of the vehicle value at 1 M. RT-PCR of CDKN1B (p27) showed retention of introns 1 and 2 at 0.5 M in A172 and in A549 lung adenocarcinoma cells. In A172 cells, therefore, herboxidiene suppresses EGFR expression without the intron 2 retention seen in lung adenocarcinoma lines, and the growth inhibition is not accounted for by loss of EGFR alone. The proliferation data are the mean and SD of three series; the RT-PCR and western blot experiments were each performed once, without replicates or statistical testing, and should be read as preliminary.

molecular biology↗

bioRxiv2026

SF3b inhibitors suppress proliferation of nonsmall cell lung cancer cells irrespective of EGFR mutation status

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are standard care for EGFR-mutant non-small cell lung cancer (NSCLC), but acquired resistance limits their durability, and alternatives that do not depend on EGFR kinase activity are needed. We asked whether inhibitors of SF3b, a core component of the U2 small nuclear ribonucleoprotein particle, act on NSCLC cells regardless of EGFR genotype. Three lung adenocarcinoma lines were treated with pladienolide B or herboxidiene at 0.01, 0.1 and 1 uM: PC9 and HCC827, both carrying an EGFR exon 19 deletion and both inhibited by gefitinib at nanomolar concentrations, and A549, which is EGFR wild type and gefitinibin sensitive. Proliferation was followed for three days by crystal violet staining, EGFR intron 2 retention was assayed by RTPCR, and EGFR protein was measured by western blotting. Both compounds produced a concentration-dependent increase in the intron 2 retained product in all three lines, and both held proliferation at or near the day 0 cell number in all three, at concentrations down to 0.01 uM. EGFR protein was lost in PC9, reduced in A549, and only partly reduced in HCC827, where a residual band persisted in lanes whose growth was fully suppressed. Since A549 is EGFR wild-type, and published knockdown data show that removing EGFR does not suppress proliferation of wild-type lines, the growth inhibition cannot be attributed to loss of EGFR alone. We read EGFR intron 2 retention as a marker of target engagement rather than as the mechanism of the growth effect. These are the results of single experiments without replicates or statistical testing and should be read as preliminary.

molecular biology↗

bioRxiv2026

Sodium butyrate inhibits the proliferation of temozolomide-resistant glioblastoma (A172) and lung adenocarcinoma (A549) cells and biphasically regulates EGFR expression

Glioblastoma carries one of the poorest prognoses of any solid tumour, and once resistance to temozolomide (TMZ) emerges there is little left to offer. Because the TMZ response is governed largely by epigenetic silencing of MGMT, histone deacetylase (HDAC) inhibitors are a rational partner for TMZ. We asked whether sodium butyrate (NaB), a short-chain fatty acid produced by the gut microbiota and a class I/IIa HDAC inhibitor, retains activity against TMZ-resistant cells. In A172 glioblastoma and A549 lung adenocarcinoma cells, NaB changed EGFR expression biphasically: EGFR exon 2-5 mRNA was induced at 0.15 mM in A172 and at 0.30 mM in A549, and was suppressed at higher concentrations, with EGFR protein following the same pattern in A172. NaB reduced proliferation of both lines from 0.31 mM in a concentration-dependent manner, more markedly in A172 than in A549. At concentrations that were inactive alone (NaB 0.30 mM, TMZ 3 {micro}M), the combination inhibited proliferation of A172 on day 3 and of A549 on days 2 and 3. TMZ-resistant sublines (A172 rTMZ, A549 rTMZ) established by stepwise exposure showed no response to TMZ 10 {micro}M alone, but NaB at 0.5 and 2.5 mM inhibited their proliferation concentration-dependently. The ratio of combination to TMZ alone was not lower in the resistant sublines than in the parental lines (A172 0.70 vs 0.86; A549 0.49 vs 0.58), indicating that the effect in resistant cells is attributable to NaB itself rather than to restored TMZ sensitivity. Millimolar exposure is the main barrier to translation.

molecular biology↗

bioRxiv2026

Decoy and antisense RNA oligonucleotides targeting the EGFR exon 3 splice site suppress proliferation of A172 glioblastoma cells

Short RNA oligonucleotides directed at the 3' splice site region of EGFR exon 3 reduced the proliferation of A172 glioblastoma cells, while the same oligonucleotides had no detectable effect on A549 lung adenocarcinoma cells. Glioblastoma carries EGFR amplification in roughly a third of IDH-wildtype cases, and the A172 line harbours a tandem duplication in the EGFR tyrosine kinase domain. Because exon definition in human genes depends on RNA-binding proteins that engage exonic sequence near splice sites, we used the SpliceAid database to identify candidate RNA-binding proteins at EGFR exons 2 and 3. Y-box binding protein 1 (YB-1, encoded by YBX1), reported to drive glioblastoma growth through its RNA-binding function, scored highly immediately adjacent to the exon 3 3' splice site. We designed four 2'-modified RNA oligonucleotides carrying a nuclear localisation signal: two antisense oligonucleotides against the exon 3 region (asRNA1, spanning the splice site; asRNA2, downstream of it), a decoy complementary to the asRNA2 target (dRNA2), and a decoy carrying the YB-1 consensus binding sequence (dYB-1). In A172 cells, all four reduced EGFR protein in a single Western blot experiment, and asRNA1, asRNA2 and dRNA2 reduced proliferation relative to scrambled RNA at days 1 to 3; dYB-1 produced a comparable reduction at day 3. None of these effects was seen in A549 cells. YB-1 protein level and subcellular distribution were unchanged by the oligonucleotides, arguing against an indirect route through altered YB-1 abundance. These observations are preliminary. Every experiment reported here was performed once: the proliferation data come from single plates with three wells per group, analysed by Dunnett's test against the scrambled-RNA control, and the Western blot, RT-PCR and immunocytochemistry panels are single runs presented as representative observations. Direct binding of YB-1 to the targeted EGFR sequence has not been demonstrated. We post this work as a preprint so that the design strategy and the initial observations are available while these questions remain open.

molecular biology↗

bioRxiv2026

Modeling the MRD state reveals the insomnia of chemotherapy-tolerant persister clones

Regardless of the success of clinical surgery, disseminated tumor cells (DTCs) can persist in distant organs, with a fraction surviving chemotherapy, which can result in minimal residual disease (MRD), a relevant reservoir for metastatic relapse. Yet, the cellular states that enable the survival and outgrowth of MRD remain poorly defined. Here, using a patient-derived tongue cancer organoid (TCO) model, we recapitulated the key features of chemotherapy-tolerant DTCs by culturing TCOs under growth-factor deprivation and chemotherapeutic stress conditions that mimic the metastatic tissue environment. Clonal-level analyses revealed a distinct subset of cells that retained proliferative capacity without entering a therapy-induced cytostatic state (hereafter referred to as cycling persisters, CPs). CPs exhibited coordinated activation of the IFN signaling pathway, Xenobiotic metabolism, and inflammatory signaling pathways, defining a transcriptional and metabolic program that enables sustained proliferation of CPs under the poor conditions. Consistently, a cell population with similar features was identified in metastatic tissues from patients. Longitudinal clonal tracking demonstrated that early metastatic recurrence is more likely driven by CPs, suggesting a novel mechanism that differs from the prevailing view that relapse arises from reactivation of dormant non-CPs. Our findings highlight a critical therapeutic oversight in relapse prevention.

cancer biology↗

bioRxiv2026

Sacituzumab Govitecan as an Effective Strategy for Sensitizing Chemoresistant HNSCC Cells to Senolytic Intervention

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent cancer worldwide and is marked by a high tumor relapse due to acquired chemoresistance, requiring alternative strategies to sensitize resistant tumors to treatment. Sacituzumab govitecan (SG), a TROP2-targeting antibody-drug conjugate, has been successful in limiting tumor progression in pretreated patients with triple-negative and hormone-receptor positive HER2-negative breast cancer. However, it has been ineffective as a monotherapy in HNSCC. This may be attributed to the promotion of senescence ultimately leading to tumor relapse. We established that isogenic cisplatin-sensitive and -resistant HNSCC cells undergo senescence following SG treatment. Senolytics have been effective in sensitizing solid tumors to standard of care chemotherapies in preclinical studies. Consequently, we investigated the effectiveness of SG treatment followed by the senolytic, ABT-263, as a two-hit therapeutic strategy against cisplatin-resistant HNSCC. SG followed by ABT-263 sensitized HNSCC cells to apoptosis via a BAK and BAX-dependent mechanism. In vivo studies confirmed that SG treatment followed by ABT-263 limited tumor progression and extended survival without notable toxicity. Thus, SG in combination with senolytic treatment may be an effective strategy for overcoming not only cisplatin-resistance but also SG resistance via targeting the senescent cell population.

cancer biology↗

bioRxiv2026

The REFLEX system enables in vivo identification of perivascular angiogenic macrophages in the heart

Direct identification of physically interacting cells in vivo remains challenging because conventional interactome analyses infer signaling partners from transcriptomes and cannot reveal which cells are in direct contact. In pressure-overload induced cardiac remodeling, VEGF-A plays a central role in the maintenance of vascular integrity and cardiac function. However, the cell type which produces VEGF-A and how the VEGF-A peptide is delivered to vascular endothelial cells remains unclear. Here, we developed a genetically encoded platform that combines REFLEX mice with HUNTERuni-seq, enabling unbiased detection and transcriptional profiling of the cells that physically interact with vascular endothelial cells. The REFLEX and HUNTERuni-seq approach identified subpopulations of Vegfa positive macrophages which we named perivascular angiogenic macrophages (PVAMs). Although the amount of VEGF-A in PVAMs is small, loss of VEGF-A in PVAMs impaired angiogenesis and systolic function during pressure overload. We additionally show that direct contact between PVAMs and endothelial cells is critical for the delivery of VEGF-A to endothelial cells. Conventional interactome analysis predicted that cardiomyocytes as dominant sources of VEGF-A in the heart. However, cardiomyocyte Vegfa deletion had no effect on capillary density nor systolic function in a model of heart failure. These results suggest that VEGF-A signaling does not rely on free diffusion through the interstitium and that cellular proximity and physical contact between PVAMs and endothelial cells are the key determinants of effective signal delivery. Together, these findings establish REFLEX and HUNTERuni-seq as a versatile platform for uncovering biologically critical cell-to-cell interactions and provide new insight into intercellular communication in pathological tissue contexts.

cell biology↗

bioRxiv2025

Dickkopf1 is a Novel Endogenous Ligand for priming NLRP3 Inflammasome in Macrophages via TLR4

Dickkopf1(DKK1) is a quintessential Wnt antagonist and immunomodulator in various inflammatory diseases. The underlying molecular mechanisms of DKK1-mediated immunomodulation remain elusive. Here, we identified TLR4 as a new receptor for DKK1 to activate NF{kappa}B pathway-mediated gene expressions and pyroptosis via NLRP3 inflammasome in human and mouse macrophages. DKK1 employed TLR4 to initiate NF{kappa}B signaling cascade via MyD88. MyD88-TAK1-NF{kappa}B pathway activation by DKK1 increased HIF1, NF{kappa}B, and NLRP3 protein expression levels, leading to pyroptosis. Unlike LPS, DKK1 did not induce IRAK4 phosphorylation, while the interaction between MyD88 and IRAK4 was maintained for downstream signaling activation. DKK1 did not induce IRF3 phosphorylation in the nucleus and failed to induce IFN{beta} gene expression, indicating differential signaling from LPS. DKK1 primed macrophages via TLR4-MyD88, resulting in NLRP3 inflammasome-mediated pyroptosis via Caspase-1 and Gasdermin D maturation with various NLRP3 inflammasome activators, including Nigericin. Our results demonstrated that DKK1 is a novel endogenous priming ligand that augments differential NF{kappa}B pathway from LPS and NLRP3 inflammasome activation via TLR4 in mouse and human macrophages.

immunology↗

bioRxiv2025

Proteasome Inhibition Enhances Lysosome-mediated Targeted Protein Degradation

Proteasome inhibitor drugs are currently used in the clinic to treat multiple myeloma and mantle cell lymphoma. These inhibitors cause accumulation of undegraded proteins, thus inducing proteotoxic stress and consequent cell death. However, cancer cells counteract this effect by activating an adaptive response through the transcription factor Nuclear factor erythroid 2-related factor 1 (NRF1, also known as NFE2L1). NRF1 induces transcriptional upregulation of proteasome and autophagy/lysosomal genes, thereby reducing proteotoxic stress and diminishing the effectiveness of proteasome inhibition. While suppressing this protective autophagy response is one potential strategy, here we investigated whether this heightened autophagy could instead be leveraged therapeutically. To this end, we designed an autophagy-targeting chimera (AUTAC) compound to selectively degrade the anti-apoptotic protein Mcl1 via the lysosome. Our results show that this lysosome-mediated targeted degradation is significantly amplified in the presence of proteasome inhibition, in a NRF1-dependent manner. Mechanistically, AUTAC-driven Mcl1 clearance requires K63-linked ubiquitination by UBC13 and TRAF6 and recognition by the cargo receptor p62/SQSTM1. The combination of the proteasome inhibitor carfilzomib and Mcl1 AUTAC synergistically promoted cell death in both in vitro models, including wild-type and proteasome inhibitor-resistant multiple myeloma and lung cancer cells, and in mouse tumor xenografts. Thus, our work offers a novel strategy for enhancing proteasome inhibitor efficacy by exploiting the adaptive autophagy response. More broadly, our study establishes a framework for amplifying lysosome-mediated targeted protein degradation, with potential applications in cancer therapeutics and beyond.

biochemistry↗

bioRxiv2024

Segregated localization of target-SNARE proteins within presynaptic terminals of Munc18-1 deficient photoreceptors

Sec1/Munc18 family proteins are essential for SNARE-mediated vesicular exocytosis. However, where SNARE proteins are localized in Munc18-1 deficient presynaptic terminals remains unclear due to the rapid degeneration of neurons lacking Munc18-1. Here, we found that removing Munc18-1 from photoreceptor cells did not result in major cellular loss until postnatal day 14, which allowed us to investigate the role of Munc18-1 in endogenous presynaptic terminals. In the absence of Munc18-1, even before major photoreceptor cell degeneration, functional impairments were present. While Munc18-1 was not required for the pre-synaptic enrichment of the t-SNARE proteins syntaxin-3 and SNAP-25, it played a critical role in their proper localization. In wild-type conditions, t-SNAREs are highly colocalized. However, in the absence of Munc18-1, their distribution becomes strikingly segregated. Immuno-electron microscopy revealed that without Munc18-1, syntaxin-3 is retained within various organelle membranes rather than being targeted to synaptic plasma membranes. These findings provide the first evidence that Munc18-1 is important to prevent segregation of syntaxin-3 and SNAP-25 within presynaptic terminals.

neuroscience↗

bioRxiv2024

Onco-fetal protein Nogo-A restricts human and mouse glioma vascularization and growth via VEGF-Notch-hippo-metabolic signaling

Glioblastoma is one of the most deadly human cancers characterized by high degrees of vascularization, but targeting its vasculature has resulted in very limited success so far. Angiogenesis, the growth of new blood vessels, is highly dynamic during brain development, enters a mostly quiescent state in the adult homeostatic brain, and is reactivated in vascular-dependent CNS diseases including brain tumors. In consequence, a better understanding of the relevance of the onco-fetal axis - describing the reactivation of fetal signaling programs in tumors - in endothelial- and perivascular cells of the human brain tumor vasculature harbors great translational potential, yet remains poorly defined. In development, neurovascular link (NVL) molecules guide both neuronal growth cones as well as capillary endothelial tip cells. Nogo-A is an NVL molecule known to inhibit axonal growth in the developing and adult CNS and to restrict angiogenesis during brain development, but its role in the mouse and human brain tumor vasculature along the onco-fetal axis remains unknown. Here, we characterize Nogo-A as an onco-fetal protein expressed in the neurovascular unit (NVU) in human fetal brains and human gliomas in vivo that negatively regulates sprouting angiogenesis and endothelial tip cells in glioma vascularization. The Nogo-A-specific Delta 20 domain restricts angiogenic sprouting and branching and promotes vascular normalization while inhibiting glioma growth in experimental gliomas. Moreover, Nogo-A expression in tumor cells negatively correlate/s with glioma malignancy in vivo. In vitro, Nogo-A Delta 20 reduced human brain- and brain tumor endothelial cell (HBMVEC, HBTMVEC) and human umbilical vein endothelial cell (HUVEC) spreading, migration, and sprouting, in a dose-dependent manner and inhibited filopodia extension glucose metabolism. Mechanistically, RNA sequencing of Nogo-A Delta 20-treated HBMVECs and HBTMVECs revealed Nogo-A Delta 20-induced positive regulation of the angiogenesis-inhibiting Dll4-Notch-pathway and inhibition of the angiogenesis-promoting VEGF-VEGFR and Hippo-YAP-TAZ pathways, whereas metabolomics and functional metabolic assays revealed Nogo-A Delta 20-induced negative regulation of endothelial glycolysis in HBMVECs and HBTMVECs. These findings characterize Nogo-A as an onco-fetal protein in the human glial brain tumor vasculature and identify Nogo-A Delta 20 signaling as an important negative regulator of human glioma vascularization and growth. Enhancing Nogo-A signaling may be an attractive alternative or combinatorial anti-angiogenic therapy to restrict human glioma/glioblastoma vascularization and growth.

neuroscience↗

bioRxiv2024

Oncogenic Mutant p53 Sensitizes Non-Small Cell Lung Cancer Cells to Proteasome Inhibition via Oxidative Stress-Dependent Induction of Mitochondrial Apoptosis

Non-small cell lung cancer (NSCLC) cells with oncogenic mutant p53 alleles (Onc-p53) exhibit significantly higher levels of proteasome activity, indicating that Onc-p53 induces proteotoxic stress which may be leveraged as a therapeutic vulnerability. Proteasome inhibitors (PIs), such as bortezomib (BTZ), can induce toxic levels of oxidative stress in cancer cells and thus we investigated whether PIs exhibit preferential cytotoxicity in Onc-p53 NSCLC cells. Indeed, BTZ and other PIs exhibited the IC50 6-7-fold lower in Onc-p53 cells vs. wild-type (WT) p53 cells. BTZ cytotoxic effects in Onc-p53 cells were nearly completely rescued by antioxidants such as N-acetyl cysteine, indicating that oxidative stress is the critical driver of BTZ-dependent cytotoxic effects in Onc-p53 cells. Importantly, we observed oxidative stress-dependent transcriptional induction of the pro-apoptotic NOXA with downstream cleaved caspase-3, consistent with apoptotic cell death in Onc-p53 but not in WT p53 cells treated with BTZ, and BTZ-generated oxidative stress was linked to nuclear translocation of NRF2 and transcriptional activation of ATF3, which in turn was required for NOXA induction. Validating BTZs translational potential in Onc-p53 NSCLC, BTZ and carboplatin or the BH3-mimetic navitoclax were synergistically cytotoxic in Onc-p53 but not WT p53 cells in vitro, and BTZ effectively limited growth of Onc-p53 NSCLC xenografts when combined with either carboplatin or navitoclax in vivo. Our data therefore support further investigation of the therapeutic utility of PIs combined with carboplatin or BH3-mimetics in Onc-p53 human NSCLC as novel therapeutic strategies. SignificanceNon-small cell lung cancer (NSCLC) is the leading cause of cancer death due, in part, to a lack of active therapies in advanced disease. We demonstrate that proteasome inhibitor/BH3-mimetic combination therapy is an active precision therapy in NSCLC cells and tumors expressing oncogenic mutant p53 alleles (Onc-p53).

cancer biology↗

bioRxiv2023

SNAP-25, but not SNAP-23, is essential for photoreceptor function and survival in mice

Vesicular transport plays critical roles in photopigment delivery at photoreceptor outer segments and glutamate exocytosis at photoreceptor synapses. Previous studies into the role of photoreceptor SNAP proteins are limited in their characterizations into only gene/protein expression and do not delve further into their functional role. Here, we examine the expression and localization of SNAP-23 and SNAP-25 mRNA and protein. Using SNAP-23 and SNAP-25 conditional knockout mice, we further evaluated the morphological and functional consequences that the absence of these proteins has on vision. Although we found that the ubiquitously expressed SNAP-23 showed weak mRNA expression in photoreceptors, removal of SNAP-23 did not result in any observable phenotype. We found that neuronal SNAP-25 is developmentally regulated and SNAP-25 mRNA undergoes mRNA trafficking to the photoreceptor inner segments coinciding with the development of photoreceptor outer segments. Removal of SNAP-25 in photoreceptor cells led to changes in both outer segment protein trafficking and synaptic integrity, resulting in a complete loss of vision in SNAP-25 cKO mice. Our results conclude that SNAP-25, but not SNAP-23, is the essential isoform for photoreceptor survival and function.

neuroscience↗

bioRxiv2023

Mouse model of multiple sclerosis induced by disrupting vesicular transport in oligodendrocytes

Multiple Sclerosis is an autoimmune demyelination disorder with unknown etiology. Despite the myelin damage, the roles of myelinating oligodendrocytes in driving disease progression remain unknown. We hypothesize that disrupting vesicular transport in oligodendrocytes during adolescence will disrupt myelin integrity and causes neuroinflammation. By creating a mouse model of SNAP-23 conditional knockout in mature oligodendrocytes, we showed that impairment in vesicular trafficking in oligodendrocytes causes demyelination. Neuroinflammation with infiltration of peripheral immune T cells into the central nervous system was observed accompanied by demyelination. Mechanistically, SNAP-23 removal in oligodendrocytes caused abnormal axon-myelin structures and impaired myelin protein trafficking, both can contribute to autoimmune activation and demyelination. With our novel animal model, we propose that oligodendrocyte injury is an endogenous early event in triggering Multiple Sclerosis. One-Sentence SummaryImpaired vesicular transport in oligodendrocytes in adults caused demyelination and inflammation driving Multiple Sclerosis

neuroscience↗

bioRxiv2023

Genomic surveillance of antimicrobial-resistant Escherichia coli in fecal sludge and sewage in Uganda

The global increase of antimicrobial resistance (AMR) is a major public health concern. An effective AMR surveillance tool is needed to track the emergence and spread of AMR. Wastewater surveillance has been proposed as a resource-efficient tool for monitoring AMR carriage in the community. Here, we performed genomic surveillance of antimicrobial-resistant Escherichia coli obtained from fecal sludge and sewage in Uganda to gain insights into E. coli epidemiology and AMR burden in the underlying population. Selective media containing different antibiotic combinations (cefotaxime, ciprofloxacin, cefotaxime + ciprofloxacin + gentamicin) were used to obtain antimicrobial-resistant E. coli from fecal sludge and sewage. Short-read sequencing was performed for the obtained isolates, and a subset of isolates (selected from predominant sequence types (STs)) was also subjected to long-read sequencing. Genomic analysis of the obtained E. coli isolates (n = 181) revealed the prevalence of clonal complex 10, including ST167 (n = 43), ST10 (n = 28), ST1284 (n = 17), and ST617 (n = 4), in both fecal sludge and sewage, irrespective of antibiotics used for selection. We also detected global high-risk clones ST1193 (n = 10) and ST131 (n = 2 clade A, n = 3 subclade C1-M27, and n = 1 subclade C2). Diverse AMR determinants, including extended-spectrum {beta}-lactamase genes (mostly blaCTX-M-15) and mutations in gyrA and parC, were identified. Analysis of the completed genomes revealed that diverse IncF plasmids and chromosomal integration were the major contributors to the spread of AMR genes in the predominant STs. This study showed that a combination of sewage surveillance (or fecal sludge surveillance) and whole-genome sequencing can be a powerful tool for monitoring AMR carriage in the underlying population.

microbiology↗

bioRxiv2022

Neuronal SNAP-23 scales hippocampal synaptic plasticity and memory

Soluble NSF Attachment protein REceptor (SNARE)-mediated membrane fusion plays a crucial role not only in presynaptic vesicle exocytosis but also in postsynaptic receptor delivery. The latter is considered particularly important for long-term synaptic plasticity and learning and memory, yet underlying mechanisms including the identity of the key SNARE proteins remain elusive. Here, we investigate the role of neuronal Synaptosomal-Associated Protein-23 (SNAP-23) by analyzing pyramidal-neuron specific SNAP-23 conditional knockout (cKO) mice. SNAP-23 immunostaining in postsynaptic spines was effectively decreased in the SNAP-23 cKO hippocampus. Electrophysiological analysis of SNAP-23 deficient neurons using acute hippocampal slices showed normal basal neurotransmission in CA3-CA1 synapses with unchanged AMPA and NMDA currents. Nevertheless, we found theta-burst stimulation induced long-term potentiation (LTP) was vastly diminished in SNAP-23 cKO. Moreover, unlike syntaxin-4 cKO mice in which both basal neurotransmission and LTP decrease manifested changes in a broad set of behavioral tasks, deficits of SNAP-23 cKO is more limited to spatial memory. Our data reveal that neuronal SNAP-23 is selectively crucial for synaptic plasticity and spatial memory without affecting basal glutamate receptor function.

neuroscience↗