Biology subjects

Kim, S.

Publications and source records attributed to Kim, S..

At least 217 records · Page 12Linked to original sources

bioRxiv2024

Remote-Controlled Wireless Bioelectronics for Fluoxetine Therapy to Promote Wound Healing in a Porcine Model

Wound healing presents a significant challenge in biomedical science, requiring precise therapeutic delivery and real-time monitoring. Bioelectronic systems offer a promising solution but remain largely unexplored for wound care, particularly in large animal models that reflect human healing dynamics. This study introduces a remote controlled wireless bioelectronic platform equipped with an iontophoretic pump to deliver fluoxetine, a selective serotonin reuptake inhibitor that promotes wound repair. In vitro and ex-vivo testing validated efficient on demand fluoxetine delivery. In vivo experiments in a porcine wound model demonstrated clear therapeutic efficacy over 3-day and 7-day periods. The system enhanced healing outcomes, increasing re-epithelialization by 37% (H&E staining), reducing the M1/M2 macrophage ratio by 33%, and stimulating neuronal growth at the wound site. This bioelectronic platform delivers fluoxetine in a controlled, remotely-controlled manner while allowing for wound direct wound imaging that can be used to monitor wound healing progress. Additionally, it allows precise dose and temporal delivery of treatment to enhance the outcome of future large animal wound healing studies.

bioengineering↗

bioRxiv2024

YibN, a bona fide interactor of YidC with implications in membrane protein insertion and membrane lipid production

YidC, a prominent member of the Oxa1 superfamily, is essential for the biogenesis of the bacterial inner membrane, significantly influencing its protein composition and lipid organization. It interacts with the Sec translocon, aiding the proper folding of multi-pass membrane proteins. It also functions independently, serving as an insertase and lipid scramblase, augmenting the insertion of smaller membrane proteins while contributing to the organization of the bilayer. Despite the wealth of structural and biochemical data available, how YidC operates remains unclear. To investigate this, we employed proximity-dependent biotin labeling (BioID), leading to the identification of YibN as a crucial component within the YidC protein environment. We then demonstrated the association between YidC and YibN by affinity purification-mass spectrometry assays conducted on native membranes, with further confirmation using on-gel binding assays with purified proteins. Co-expression studies and in vitro assays indicated that YibN enhances the production and membrane insertion of YidC substrates, such as M13 and Pf3 phage coat proteins, ATP synthase subunit c, and various small membrane proteins like SecG. Additionally, the overproduction of YibN was found to stimulate membrane lipid production and promote inner membrane proliferation, perhaps by interfering with YidC lipid scramblase activity. Consequently, YibN emerges as a significant physical and functional interactor of YidC, influencing membrane protein insertion and lipid organization.

biochemistry↗

bioRxiv2024

CRISPR-Edited DPSCs, Constitutively Expressing BDNF Enhance Dentin Regeneration in Injured Teeth

Dental caries, a prevalent global health issue, results from complex bacterial interactions. In response to harmful stimuli, a desirable outcome for the tooth is the formation of tertiary dentin, a protective reparative process that generates new hard tissue. This reparative dentinogenesis is associated with significant inflammation, which triggers the recruitment and differentiation of dental pulp stem cells (DPSCs). Previously, we have demonstrated that brain-derived neurotrophic factor (BDNF) and its receptor TrkB, key mediators of neural functions, are activated during the DPSC-mediated dentin regeneration process. In this study, we further define the role of inflammation in this process and apply stem cell engineering to enhance dentin regeneration in injured teeth. Our data show that TrkB expression and activation in DPSCs rapidly increase during odontogenic differentiation, further amplified by inflammatory inducers and mediators such as TNF, LTA, and LPS. An in vivo dentin formation assessment was conducted using a mouse pulp-capping/caries model, where CRISPR-engineered DPSCs overexpressing BDNF were transplanted into inflamed pulp tissue. This transplantation significantly enhanced dentin regeneration in injured teeth. To further explore potential downstream pathways, we conducted transcriptomic profiling of TNF-treated DPSCs, both with and without TrkB antagonist CTX-B. The results revealed significant changes in gene expression related to immune response, cytokine signaling, and extracellular matrix interactions. Taken together, our study advances our understanding of the role of BDNF in dental tissue engineering using DPSCs and identifies potential therapeutic avenues for improving dental tissue repair and regeneration strategies.

bioengineering↗

bioRxiv2024

Transcription factors form a ternary complex with NIPBL/MAU2 to localize cohesin at enhancers

While the cohesin complex is a key player in genome architecture, how it localizes to specific chromatin sites is not understood. Recently, we and others have proposed that direct interactions with transcription factors lead to the localization of the cohesin-loader complex (NIPBL/MAU2) within enhancers. Here, we identify two clusters of LxxLL motifs within the NIPBL sequence that regulate NIPBL dynamics, interactome, and NIPBL-dependent transcriptional programs. One of these clusters interacts with MAU2 and is necessary for the maintenance of the NIPBL-MAU2 heterodimer. The second cluster binds specifically to the ligand-binding domains of steroid receptors. For the glucocorticoid receptor (GR), we examine in detail its interaction surfaces with NIPBL and MAU2. Using AlphaFold2 and molecular docking algorithms, we uncover a GR-NIPBL-MAU2 ternary complex and describe its importance in GR-dependent gene regulation. Finally, we show that multiple transcription factors interact with NIPBL-MAU2, likely using interfaces other than those characterized for GR.

molecular biology↗

bioRxiv2024

PISA: versatile microscope for 3D single molecule light sheet imaging

Light sheet microscopy combines high sensitivity and imaging speeds with low photodamage, however a remaining hurdle to its widespread adoption is its requirement for special sample preparation. Our new microscope - planar illumination microscope for single molecule imaging for all purpose (PISA) - significantly relieves these restrictions to enable light sheet imaging of coverslip-mounted samples as commonly analyzed in biological microscopes. We show how this technology now permits high-throughput imaging using multi-well plates. Further, the ability of 3D single molecule imaging in microlitre or mm3 scale volumes over the coverslip improves the sensitivity of biochemical gel-based fluorometric assays to atto/zepto molar levels. PISA will facilitate widespread adoption of light sheet imaging for a variety of biological, biochemical and medical investigations.

biophysics↗

bioRxiv2024

Lineage-specific amino acids define functional attributes of the protomer-protomer interfaces for the Rad51 and Dmc1 recombinases

Most eukaryotes possess two Rad51/RecA family DNA recombinases that are thought to have arisen from an ancient gene duplication event: Rad51, which is expressed in both mitosis and meiosis; and Dmc1, which is only expressed in meiosis. To explore the evolutionary relationship between these recombinases, here, we present high-resolution CryoEM structures of S. cerevisiae Rad51 filaments and S. cerevisiae Dmc1 filaments bound to ssDNA, which reveal a pair of stacked interfacial aromatic amino acid residues that are nearly universally conserved in Rad51 but are absent from Dmc1. We use a combination of bioinformatics, genetic analysis of natural sequence variation, and deep mutational analysis to probe the functionally tolerated sequence space for these stacked aromatic residues. Our findings demonstrate that the functional landscape of the interfacial aromatic residues within the Rad51 filament is highly constrained. In contrast, the amino acids at the equivalent positions within the Dmc1 filament exhibit a broad functional landscape. This work helps highlight the distinct evolutionary trajectories of these two eukaryotic recombinases, which may have contributed to their functional and mechanistic divergence. AUTHOR SUMMARYMost eukaryotic organisms have two closely related proteins, Rad51 and Dmc1, that are needed for different aspects of genetic recombination. These proteins may have evolved from a single gene that was duplicated during the early evolution of eukaryotes. Rad51 is active during both normal cell division (mitosis) and sexual reproduction (meiosis), while Dmc1 is only active during meiosis. To better understand how these proteins are related, we studied their three-dimensional structures using high resolution cryogenic electron microscopy. Our findings show that Rad51 has a specific set of conserved amino acids located at the protein interfaces, but this set of amino acids is different in Dmc1. We used a series of genetic approaches to analyze how these amino acids affect the proteins function. Our results show that Rad51 has a strict set of rules governing the identify of these amino acids, whereas Dmc1 does not. This research sheds light on how Rad51 and Dmc1 have evolved differently, leading to distinct functions in genetic recombination.

genetics↗

bioRxiv2024

Stereoselectivity of Aminoacyl-RNA Loop-closing Ligation

The origin of amino acid homochirality remains an unresolved question in the origin of life. The requirement of enantiopure nucleotides for nonenzymatic RNA copying strongly suggests that homochirality of nucleotides and RNA arose early. However, this leaves open the question of whether and how homochiral RNA subsequently imposed biological homochirality on other metabolites including amino acids. Previous studies have reported moderate stereoselectivity for various aminoacyl-RNA transfer reactions. Here we examine aminoacyl-RNA loop-closing ligation, a reaction that captures aminoacylated RNA in a stable phosphoramidate product, such that the amino acid bridges two nucleotides in the RNA backbone. We find that the rate of this reaction is much higher for RNA aminoacylated with L-amino acids than D-amino acids. We present an RNA sequence that near-exclusively captures L-amino acids in loop-closing ligation. Finally, we demonstrate that ligation of aminoacyl-L-RNA results in inverse stereoselectivity for D-amino acids. The observed stereochemical link between D-RNA and L-amino acids in the synthesis of RNA stem-loops containing bridging amino acids constitutes a stereoselective structure building process. We suggest that this process led to a selection for the evolution of aminoacyl-RNA synthetase ribozymes that were selective for L-amino acids, thereby setting the stage for the subsequent evolution of homochiral peptide and ultimately protein synthesis.

biochemistry↗

bioRxiv2024

Anatomical Region-Specific Transcriptomic Signatures and the Role of Epithelial Cells in Pterygium Inflammation: A Multi-Omics Analysis

BackgroundThe anatomy of pterygium consists of the head, neck, and body. Prior studies have examined the three parts collectively, yet the treatment methods and their success rates differ based on the anatomical characteristics. In this study, we divide the pterygium tissue into Main (head and neck) and Acc (body) to investigate its pathogenesis across regions. PurposesThis study aims to understand the pathogenesis and identify potential therapeutic targets of pterygium. Through a robust multi-omics analysis of bulk and single-cell RNA sequencing (RNA-seq) data from pterygium patients, we focus on the expression of inflammatory and mitochondrial energy pathways and identify potential genes responsible for the upregulated pathways in pterygium. MethodsWe collected bulk RNA-seq data from six pterygium patients and single-cell RNA-seq data from two pterygium patients. We then investigated the pathway enrichment, pathway correlation, differential gene expressions, protein-protein interactions, and cell-cell communications of pterygium. ResultsFrom the analysis of bulk RNA-seq data, the distribution of sample points from the principal component analysis plot and the pathways enriched from the Gene Ontology analysis showed distinct expression patterns in the Acc group compared to the Main and control groups. This suggested the need to separate the Main and Acc regions within pterygium samples and utilize single-cell RNA-seq data to understand the differences between the Main and control groups that the bulk data could not capture. The annotation of integrated single-cell data revealed a cluster of epithelial cells containing only pterygium samples. Cells from this cluster exhibited significant contributions to the ANGPTL, IL1, and KLK signaling networks in the cell-cell communication analysis. We also observed significant upregulation of the cells in the inflammatory pathways related to integrated stress response and the renin-angiotensin-aldosterone system, both of which showed high correlations with energy metabolism pathways. Significant changes in the expression of multiple pro-inflammatory, antioxidant, and immune-related genes were also identified. ConclusionThe different expression patterns between the Main and Acc groups suggest the need to consider different anatomical regions separately in future studies of pterygium. Additionally, the significant role epithelial cells from the Main group play in the inflammation of pterygium presents a potential clinical approach to the disease.

bioinformatics↗

bioRxiv2024

Reconstitution of SPO11-dependent double-strand break formation

Homologous meiotic recombination starts with DNA double-strand breaks (DSBs) generated by SPO11 protein1. SPO11 is critical for meiosis in most species but the DSBs it makes are also dangerous because of their mutagenic2 and gametocidal3 potential, so cells must foster SPO11s beneficial functions while minimizing its risks4. SPO11 mechanism and regulation remain poorly understood. Here we report reconstitution of DNA cleavage in vitro with purified recombinant mouse SPO11 bound to its essential partner TOP6BL. Similar to their yeast orthologs5,6, SPO11- TOP6BL complexes are monomeric (1:1) in solution and bind tightly to DNA. Unlike in yeast, however, dimeric (2:2) assemblies of mouse SPO11-TOP6BL cleave DNA to form covalent 5' attachments requiring SPO11 active site residues, divalent metal ions, and SPO11 dimerization. Surprisingly, SPO11 can also manifest topoisomerase activity by relaxing supercoils and resealing DNA that it has nicked. Structure modeling with AlphaFold37 illuminates the protein-DNA interface and suggests that DNA is bent prior to cleavage. Deep sequencing of in vitro cleavage products reveals a rotationally symmetric base composition bias that partially explains DSB site preferences in vivo. Cleavage is inefficient on complex DNA substrates, partly because SPO11 is readily trapped in DSB-incompetent (presumably monomeric) binding states that exchange slowly. However, cleavage is improved by using substrates that favor DSB-competent dimer assembly, or by fusing SPO11 to an artificial dimerization module. Our results inform a model in which intrinsically feeble dimerization restrains SPO11 activity in vivo, making it exquisitely dependent on accessory proteins that focus and control DSB formation so that it happens only at the right time and the right places.

biochemistry↗

bioRxiv2024

YTHDF1 and YTHDC1 m6A reader proteins regulate HTLV-1 tax and hbz activity

Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus responsible for adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a progressive neurodegenerative disease. Regulation of viral gene expression plays a key role in viral persistence and pathogenesis. However, the molecular mechanisms underlying this fine-tuned regulation remain poorly understood. Little is known regarding RNA chemical modifications of HTLV-1 RNA and how these affect viral biology and disease development. Posttranscriptional chemical modification of RNA is common in eukaryotes, with N6-methyladenosine (m6A) being the most prevalent. In this study, we investigated the role of m6A RNA modifications on HTLV-1 gene expression. Using MeRIP-Seq, we mapped sites of m6A modification to the 3 end of the viral genome. We found HTLV-1 RNA, as well as viral oncogene transcripts tax and hbz, contained m6A modifications. m6A-depletion in HTLV-1-transformed cells decreased sense-derived viral genes (Tax, Gag, Env) and increased antisense-derived Hbz expression. Tax and hbz transcripts were bound by reader proteins YTHDF1 and YTHDC1 in a panel of HTLV-1 T-cell lines. Using expression vectors and shRNA-mediated knockdown, we found YTHDF1 had opposing effects on viral gene expression - decreasing sense-derived viral genes and increasing antisense-derived Hbz. Upon further study, the YTHDF1 effects on tax abundance were dependent on tax m6A deposition. The nuclear m6A reader protein YTHDC1 affected the abundance of both sense- and antisense-derived viral transcripts and specifically enhanced the nuclear export of tax transcript. Collectively, our results demonstrate global m6A levels and m6A reader proteins YTHDF1 and YTHDC1 regulate HTLV-1 gene expression. ImportanceHuman T-cell leukemia virus type 1 (HTLV-1) persistence and pathogenesis are controlled through tight regulation of viral gene expression. The fate of RNA can be controlled by epigenetic modifications which impact gene expression without altering the DNA sequence. Our study details the impact of N6-methyladenosine (m6A) RNA chemical modifications on HTLV-1 gene expression. We found reductions in global m6A levels affected viral gene expression, decreasing Tax and other sense-derived viral genes, while increasing the antisense-derived Hbz. Our results suggest the oncogenic viral transcripts, tax and hbz, are m6A-modified in cells. We found these viral RNA modifications are interpreted by reader proteins YTHDF1 and YTHDC1, which dictate the fate of the viral RNA. Understanding HTLV-1 RNA chemical modifications offers potential insights into novel therapeutic strategies for HTLV-1-associated diseases.

molecular biology↗

bioRxiv2024

Therapeutic benefits of maintaining CDK4/6 inhibitors and incorporating CDK2 inhibitors beyond progression in breast cancer

CDK4/6 inhibitors (CDK4/6i) with endocrine therapy are standard for hormone receptor-positive (HR+) metastatic breast cancer. However, most patients eventually develop resistance and discontinue treatment, and there is currently no consensus on effective second-line strategies. Here, we demonstrate that maintaining CDK4/6i therapy, either alone or in combination with CDK2 inhibitors (CDK2i), slows the growth of drug-resistant HR+ models by prolonging G1 progression. Mechanistically, sustained CDK4/6 blockade in drug-resistant cells reduces E2F transcription and delays G1/S via a non-canonical, post-translational regulation of retinoblastoma protein (Rb). Durable suppression of both CDK2 activity and growth of drug-resistant cells requires co-administration of CDK2i with CDK4/6i. Moreover, cyclin E overexpression drives resistance to the combination of CDK4/6i and CDK2i. These findings elucidate how continued CDK4/6 blockade constrains resistant tumors and support clinical strategies that maintain CDK4/6i while selectively incorporating CDK2i to overcome resistance.

cancer biology↗

bioRxiv2024

Single-molecule imaging reveals the role of membrane-binding motif and C-terminal domain of RNase E in its localization and diffusion in Escherichia coli

In Escherichia coli, RNase E, a central enzyme in RNA processing and mRNA degradation, contains a catalytic N-terminal domain (NTD), a membrane-targeting sequence (MTS), and a C-terminal domain (CTD). We investigated how MTS and CTD influence RNase E localization, diffusion, and function. Super-resolution microscopy revealed that [~]93% of RNase E localizes to the inner membrane and exhibits slow diffusion similar to polysomes. Comparing the native amphipathic MTS with a transmembrane motif showed that the MTS confers slower diffusion and stronger membrane binding. The CTD further slows diffusion by increasing mass but unexpectedly weakens membrane association. RNase E mutants with partial cytoplasmic localization displayed enhanced co-transcriptional degradation of lacZ mRNA. These findings indicate that variations in the MTS and the presence of the CTD shape the spatiotemporal organization of RNA processing in bacterial cells, providing mechanistic insight into how RNase E domain architecture influences its cellular function.

microbiology↗

bioRxiv2024

Inhibition of Yes-Associated Protein (YAP) with Verteporfin Enhances Radiosensitivity in Chordoma by Inducing G2M Arrest and Inhibiting the DNA Damage Response

Chordomas are locally invasive cancers that are highly resistant to radiotherapy. The Brachyury and Yes-Associated Protein (YAP) regulatory axis has been implicated as the primary driver of tumorigenicity in chordoma. Here, we aimed to enhance chordoma radiosensitivity by repurposing the FDA-approved YAP inhibitor, Verteporfin. We used five patient-derived chordoma cell lines and generated two YAP1 knockdown cell lines to validate the YAP-targeting phenotype in chordoma. Verteporfin treatment reduced the expression of DNA damage repair proteins and genes. YAP inhibition with either verteporfin or YAP knockdown resulted in enhanced DNA double-stranded breaks after radiation via inhibition of the DNA damage repair pathway and accumulation of cells in the G2M phase. Verteporfin inhibited chordoma tumor growth alone and in combination with radiation in a xenograft mouse model treated with verteporfin loaded microparticles, resulting in sensitization of chordoma tumors to radiation. YAP inhibition with verteporfin renders chordoma more sensitive to radiation via inhibition of the DNA damage repair cascade and accumulation of cells in G2M when they are most susceptible to radiation damage.

cancer biology↗

bioRxiv2024

Effect of digital noise-reduction processing on subcortical speech encoding and relationship to behavioral outcomes

Perceptual benefits from digital noise reduction (NR) vary among individuals with different noise tolerance and sensitivity to distortions introduced in NR-processed speech; however, the physiological bases of the variance are understudied. Here, we developed objective measures of speech encoding in the ascending pathway as candidate measures of individual noise tolerance and sensitivity to NR-processed speech using the brainstem responses to speech syllable /da/. The speech-evoked brainstem response was found to be sensitive to the addition of noise and NR processing. The NR effects on the consonant and vowel portion of the responses were robustly quantified using response-to-response correlation metrics and spectral amplitude ratios, respectively. Further, the f0 amplitude ratios between conditions correlated with behavioral accuracy with NR. These findings suggest that investigating the NR effects on bottom-up speech encoding using brainstem measures is feasible and that individual subcortical encoding of NR-processed speech may relate to individual behavioral outcomes with NR.

neuroscience↗

bioRxiv2024

Ketamine reverses chronic stress-induced behavioral changes via the expression of Ca2+-permeable AMPA receptors in mice

Background and Purpose: Chronic stress affects brain functions leading to the development of mental disorders like anxiety and depression, as well as cognitive decline and social dysfunction. Among many biological changes in chronically stressed brains, disruptions in AMPA Receptor (AMPAR)-mediated synaptic transmission in the hippocampus are associated with stress responses. We have revealed that low-dose ketamine rapidly induces the expression of GluA1-containing, GluA2-lacking Ca2+-Permeable AMPARs (CP-AMPARs), which enhances glutamatergic synaptic strength in hippocampal neurons. Additionally, subanesthetic low-dose ketamine decreases anxiety- and depression-like behaviors in naive animals. In addition to reducing depression, some research indicates that ketamine may have protective effects against chronic stress in both humans and animals. However, the role of CP-AMPARs in the actions of ketamine's antistress effects is largely unknown. Experimental Approach: We use whole-cell patch-clamp recordings from CA1 pyramidal neurons in female and male hippocampal slices and multiple behavioral assays including reciprocal social interaction, contextual fear conditioning, and tail suspension test. Key Results: We demonstrate that low-dose ketamine treatment reverses chronic restraint stress (CRS)-induced social dysfunction, hippocampus-dependent fear memory loss, and depression-like behavior in both female and male mice. Furthermore, we show that the ketamine-induced antistress effects on these behaviors are dependent on CP-AMPARs. Conclusion and Implications: Our findings suggest that subanesthetic low-dose ketamine rapidly triggers synaptic insertion of CP-AMPARs in the hippocampus, which induces antidepressant and antistress effects.

neuroscience↗

bioRxiv2024

Parallel neuroinflammatory pathways to cerebrovascular injury and amyloid-beta in Alzheimer's disease

ImportanceWhile the hallmark pathologies of amyloid-beta (A{beta}) and tau in Alzheimers disease (AD) are well documented and even part of the definition, upstream neuroinflammation is thought to play an important role but remains poorly understood. ObjectivesWe tested whether two distinct neuroinflammatory markers are associated with cerebrovascular injury and A{beta}, and whether these markers are associated with plasma phosphorylated tau (pTau) concentration, medial temporal lobe (MTL) cortical and hippocampal atrophy, and memory deficits. We examined neuroinflammatory markers plasma YKL-40 and GFAP, due to previous conflicting evidence relating YKL-40 and GFAP to AD pathogenic markers. DesignCross-sectional data from a community observational study (Biomarker Exploration in Aging, Cognition, and Neurodegeneration - BEACoN) were included. SettingAll participants were enrolled in a single site, at University of California, Irvine. Participants126 participants were included if they had at least one of the following measures available: neuropsychological data, MRI, A{beta}-PET, or plasma. ExposuresPlasma YKL-40 and plasma glial fibrillary acidic protein (GFAP) levels. Main outcomes and measuresWhite matter hyperintensity (WMH) volume, 18F-florbetapir (FBP) PET mean SUVR, plasma phosphorylated tau (pTau-217) concentration, MTL cortical thickness, hippocampal volume, and memory function assessed by Rey Auditory Verbal Learning Test. Using path analysis, we tested whether higher plasma YKL-40 and GFAP are associated with WMH and A{beta}, and whether these converge to downstream markers of tauopathy, MTL neurodegeneration, and memory deficits. ResultsIn older adults without dementia (N=126, age=70.60+6.29, 62% women), we found that higher plasma YKL-40 concentration was associated with greater WMH volume, while higher plasma GFAP concentration was related to increased FBP SUVR. Further, higher plasma GFAP, WMH and FBP SUVR were independently associated with increased pTau-217. In turn, plasma pTau-217 was associated with reduced MTL cortical thickness and hippocampal volume. Subsequently, only reduced hippocampal volume was related to lower memory function. Conclusions and RelevanceNeuroinflammatory markers contribute to parallel pathways of cerebrovascular injury and A{beta}, which converge to tau-associated neurodegeneration and memory deficits in older adults. These observations underscore the need for a more comprehensive approach to developing an AD framework and treatment strategies. KEY POINTSO_ST_ABSQuestionC_ST_ABSHow does neuroinflammation impact downstream features of cerebrovascular injury and amyloid-beta (A{beta}) in Alzheimers disease? FindingsIn this study of 126 older adults without dementia, we found evidence for two distinct neuroinflammatory pathways that lead to neurodegeneration and memory deficits. One path involves plasma YKL-40 and its impact on cerebrovascular injury, as measured by white matter hyperintensities (WMH) on MRI scans. The other involves plasma glial fibrillary acidic protein (GFAP) and its impact on A{beta} deposition measured via 18F-florbetapir (FBP) PET. Both pathways converged on tauopathy, measured by plasma pTau-217, which was associated with lower medial temporal lobe (MTL) cortical thickness and hippocampal volume, and consequently, memory deficits. MeaningInflammation acts on Alzheimers disease mechanisms via multiple distinct and parallel pathways which converge downstream onto neurodegeneration. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/616579v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@2d3c39org.highwire.dtl.DTLVardef@1ccc453org.highwire.dtl.DTLVardef@6d40bdorg.highwire.dtl.DTLVardef@b543cb_HPS_FORMAT_FIGEXP M_FIG C_FIG Credit: BioRender was used to help create this graphical abstract.

neuroscience↗

bioRxiv2024

Characterization of newly isolated bacteriophages targeting carbapenem-resistant Klebsiella pneumoniae

Klebsiella pneumoniae, a Gram-negative opportunistic pathogen, is increasingly resistant to carbapenems in clinical settings. This growing problem necessitates the development of alternative antibiotics, with phage therapy being one promising option. In this study, we investigated novel phages targeting carbapenem-resistant Klebsiella pneumoniae (CRKP) and evaluated their lytic capacity against clinical isolates of CRKP. First, 23 CRKP clinical isolates were characterized using Multi-locus Sequence Typing (MLST), carbapenemase test, string test, and capsule typing. MLST classified the 23 K. pneumoniae isolates into 10 sequence types (STs), with the capsule types divided into nine known and one unknown type. From sewage samples collected from a tertiary hospital, 38 phages were isolated. Phenotypic and genotypic characterization of these phages was performed using Random Amplification of Polymorphic DNA-PCR (RAPD-PCR), transmission electron microscopy (TEM), and whole genome sequencing (WGS) analysis. Host spectrum analysis revealed that each phage selectively lysed strains sharing the same STs as their hosts, indicating ST-specific activity. These phages were subtyped based on their host spectrum and RAPD-PCR, identifying nine and five groups, respectively. Fourteen phages were selected for further analysis using TEM and WGS, revealing 13 Myoviruses and one Podovirus. Genomic analysis grouped the phages into three clusters: one closely related to Alcyoneusvirus, one to Autographiviridae, and others to Straboviridae. Our results showed that the host spectrum of K. pneumoniae-specific phages corresponds to the STs of the host strain. These 14 novel phages also hold promise as valuable resources for phage therapy against CRKP.

microbiology↗

bioRxiv2024

Multimodal Spatial Profiling Reveals Immune Suppression and Microenvironment Remodeling in Fallopian Tube Precursors to High-Grade Serous Ovarian Carcinoma

High-Grade Serous Ovarian Cancer (HGSOC) originates from fallopian tube (FT) precursors. However, the molecular changes that occur as precancerous lesions progress to HGSOC are not well understood. To address this, we integrated high-plex imaging and spatial transcriptomics to analyze human tissue samples at different stages of HGSOC development, including p53 signatures, serous tubal intraepithelial carcinomas (STIC), and invasive HGSOC. Our findings reveal immune modulating mechanisms within precursor epithelium, characterized by chromosomal instability, persistent interferon (IFN) signaling, and dysregulated innate and adaptive immunity. FT precursors display elevated expression of MHC-class I, including HLA-E, and IFN-stimulated genes, typically linked to later-stage tumorigenesis. These molecular alterations coincide with progressive shifts in the tumor microenvironment, transitioning from immune surveillance in early STICs to immune suppression in advanced STICs and cancer. These insights identify potential biomarkers and therapeutic targets for HGSOC interception and clarify the molecular transitions from precancer to cancer. STATEMENT OF SIGNIFICANCEThis study maps the immune response in fallopian tube precursors of high-grade serous ovarian cancer, highlighting localized interferon signaling, CIN, and competing immune surveillance and suppression along the progression axis. It provides an explorable public spatial profiling atlas for investigating precancer mechanisms, biomarkers, and early detection and interception strategies.

cancer biology↗