Biology subjects

Ding, L.

Publications and source records attributed to Ding, L..

At least 55 records · Page 3Linked to original sources

bioRxiv2025

Palmdelphin facilitates R-spondin2 secretion to activate Wnt signaling and promote colorectal cancer stemness and tumorigenesis

The Wnt signaling pathway is a key driver of stemness and progression which contributes to mortality in colorectal cancer (CRC). R-spondins bind to LGR receptors to inhibit ubiquitin E3 ligases, thus protecting Frizzled from degradation and activating downstream Wnt signaling. Herein, we identify Palmdelphin (PALMD) as a functional marker of CRC stem cells, interspersed between intestinal and colonic crypt base epithelial cells, and predictive of aggressive CMS4 CRC and poor survival. Gene knockdown and overexpression studies revealed that PALMD initiates paracrine activation of Wnt/{beta}-catenin signaling via interacting with and facilitating the secretion of R-spondin2 (RSPO2), resulting in enhanced stemness and tumor growth in vitro and in vivo. Physiologic or pharmacologic inhibition of the PALMD-RSPO2 axis using R-spondin2-specific antibody or 6-methyl-1,3,8-trihydroxyanthraquinone (emodin), respectively, attenuates PALMD- mediated Wnt reporter activation, self-renewal, and tumorigenesis in cell and patient-derived organoid models. Together, these findings identify PALMD as a previously unknown player in Wnt signaling in CRC, and underscore the pro-tumorigenic role of R-spondin2 in this context.

cancer biology↗

bioRxiv2025

KSHV Reprograms Host RNA Splicing via FAM50A to Activate STAT3 and Drive Oncogenic Cellular Transformation

RNA alternative splicing is a fundamental cellular process implicated in cancer development. Kaposis sarcoma-associated herpesvirus (KSHV), the etiological agent of multiple human malignancies, including Kaposis sarcoma (KS), remains a significant concern, particularly in AIDS patients. A CRISPR-Cas9 screening of matched primary rat mesenchymal stem cells (MM) and KSHV-transformed MM cells (KMM) identified key splicing factors involved in KSHV-induced cellular transformation. To elucidate the mechanisms by which KSHV-driven splicing reprogramming mediates cellular transformation, we performed transcriptomic sequencing, identifying 131 differential alternative splicing transcripts, with exon skipping as the predominant event. Notably, these transcripts were enriched in vascular permeability, multiple metabolic pathways and ERK1/2 signaling cascades, which play key roles in KSHV-induced oncogenesis. Further analyses of cells infected with KSHV mutants lacking latent genes including vFLIP, vCyclin and viral miRNAs, as well as cells overexpressing LANA, revealed their involvement in alternative splicing regulation. Among the identified splicing factors, FAM50A, a component of the spliceosome complex C, was found to be crucial for KSHV-mediated transformation. FAM50A knockout resulted in distinct splicing profiles in both MM and KMM cells, and significantly inhibited KSHV-driven proliferation, cellular transformation and tumorigenesis. Mechanistically, FAM50A knockout altered SHP2 splicing, promoting an isoform with enhanced enzymatic activity that led to reduced STAT3 Y705 phosphorylation in KMM cells. These findings reveal a novel paradigm in which KSHV hijacks host splicing machinery, specifically FAM50A-mediated SHP2 splicing, to sustain STAT3 activation and drive oncogenic transformation. ImportanceKaposis sarcoma-associated herpesvirus (KSHV) causes cancers such as Kaposis sarcoma, particularly in AIDS patients. This study uncovers how KSHV hijacks a fundamental cellular process called RNA splicing to promote cancer development. We identified key splicing events that alter critical pathways involved in vascular permeability, metabolism, and oncogenic signaling, particularly ERK1/2 and STAT3. A specific protein, FAM50A, was found to be essential for KSHV-driven cancerous transformation. Removing FAM50A disrupted splicing, weakening cancer-promoting signals. These findings provide new insights into how viruses manipulate host cells to drive cancer and highlight RNA splicing as a potential target for future therapies.

cancer biology↗

bioRxiv2025

TEMI: Tissue Expansion Mass Spectrometry Imaging

The spatial distribution of diverse biomolecules in multicellular organisms is essential for their physiological functions. High-throughput in situ mapping of biomolecules is crucial for both basic and medical research, and requires high scanning speed, spatial resolution, and chemical sensitivity. Here, we developed a Tissue Expansion method compatible with matrix-assisted laser desorption/ionization Mass spectrometry Imaging (TEMI). TEMI reaches single-cell spatial resolution without sacrificing voxel throughput and enables the profiling of hundreds of biomolecules, including lipids, metabolites, peptides (proteins), and N-glycans. Using TEMI, we mapped the spatial distribution of biomolecules across various mammalian tissues and uncovered metabolic heterogeneity in tumors. TEMI can be easily adapted and broadly applied in biological and medical research, to advance spatial multi-omics profiling.

molecular biology↗

bioRxiv2025

High-speed mapping of whole-mouse peripheral nerves at subcellular resolution

In contrast to the rapid advancements in mesoscale connectomic mapping of the mammalian brain, similar mapping the peripheral nervous system has remained challenging due to the bodys size and complexity. Here, we present a high-speed blockface volumetric imaging system with an optimized workflow of whole-body clearing, capable of imaging the entire adult mouse at micrometer resolution within 40 hours. Three-dimensional reconstruction of individual spinal fibers in Thy1-EGFP mice reveals distinct morphological features of sensory and motor projections along the ventral and dorsal rami. Immunostaining facilitates body-wide mapping of sympathetic nerves and their branches, highlighting their perivascular patterns in limb muscles, bones, and most visceral organs. Viral tracing elucidates the fine architecture of vagus nerves and individual vagal fibers, revealing unexpected projection routes to various organs. Our approach offers an effective means to achieve a holistic understanding of cellular-level interactions among different systems that underlie body physiology and disease. HighlightsO_LIImaging of whole adult mouse at uniform subcellular resolution within 40 hours C_LIO_LIReconstruction of 191 thoracic spinal neuron projections for Thy1-EGFP mice C_LIO_LIMapping of immunolabeled sympathetic projections and their perivascular patterns C_LIO_LIResolving virus-labeled architecture of vagus nerves and complex single-fiber routes C_LI

neuroscience↗

bioRxiv2024

Discovery and Biosynthesis of Nyuzenamides D and E by Genome Mining in Streptomyces hygroscopicus

Nyuzenamides belong to the class of bioactive cinnamoyl moiety containing non-ribosomal peptides (NRPs). However, their biosynthetic gene cluster (BGC) remains unconfirmed. Genome-mining revealed a putative nyu BGC in Streptomyces hygroscopicus DSM 40578. Nyuzenamides D (1) and E (2) were subsequently isolated, and the structures were elucidated by detailed NMR spectroscopic and MS spectrometric data analyses. The absolute configuration of 1 was determined by a single-crystal X-ray diffraction study. Through retro-biosynthesis and CRISPR-genome editing, the non-ribosomal peptide synthetase biosynthetic gene cluster for nyuzenamides was confirmed. Our discovery enriches the diversity of cinnamoyl-containing nonribosomal peptides and validates the biosynthetic gene clusters for future genome-mining research.

microbiology↗

bioRxiv2024

Small molecule activation of the tumor suppressor kinase LKB1

The ability to identify and target oncogenic signals has transformed clinical oncology. Drug development for targeted therapies has historically focused on the inhibition of oncogenic kinases and GTPases. However, many cancer patients do not benefit from targeted approaches because their tumors lack targetable mutations. Therapeutic augmentation of tumor suppressive signaling could be a viable alternative but poses challenges. Specifically, designing compounds capable of stimulating kinase activity is more structurally challenging than inhibitor design, and most kinases lack targetable allosteric pockets. Inactivation of the liver kinase B1 (LKB1) tumor suppressor kinase is associated with poor prognosis and therapeutic resistance. Thus, augmented LKB1 function could be beneficial for cancer patients whose tumors retain intact copies of the gene. LKB1 signals as part of an obligate trimer including the scaffolding protein Mouse protein-25 (MO25) and the pseudokinase (PSK) STE20-related kinase adapter protein (STRAD). As STRAD binds but does not metabolize ATP, it provides the opportunity for a novel activation strategy. We have developed STRAD-binding compounds capable of activating LKB1 and demonstrate the therapeutic benefits of LKB1 activation in a target-dependent manner within cancer cell lines.

biochemistry↗

bioRxiv2024

Improved split prime editors enable efficient in vivo genome editing

Prime editor (PE) is a precise genome-editing tool that enables all 12 possible base-to-base conversions, as well as insertions and deletions, that does not require DSBs or donor DNA. The efficient delivery of prime editors in vivo is critical for realizing the full potential of prime editing in disease modeling and therapeutic correction. Although PE has been divided into two halves and delivered using dual adeno-associated viruses (AAVs), editing efficiency at different gene loci varies among split sites, and efficient split sites within Cas9 nickase are limited. In this study, by screening multiple split sites, we demonstrated that 1115 (Asn) is an efficient split site when delivering PE by dual-AAV. Besides, we utilized a feature reported by others recently that RNase could be detached from the Cas9n and designed split sites in the first half of Cas9n. We found that split-PE-367 enabled high prime editing efficiency with Rma intein. To test the editing efficiency in vivo, dual-AAV split-ePE3-367 was packaged in AAV9 and delivered by tail vein injection in mice, achieving 24.4% precise genome editing 4 weeks after injection. Our findings establish an alternative split-PE architecture that could achieve robust gene editing efficiency, facilitating the potential utility both in model organisms and as a therapeutic modality.

genomics↗

bioRxiv2024

Modeling Thoracic Aortic Dissection Using Patient-Specific iPSCs Reveals VSMC Dysfunction and Extracellular Matrix Dysregulation

Thoracic aortic dissection (TAD) is a life-threatening condition characterized by medial degeneration and vascular smooth muscle cell (VSMC) dysfunction, with no effective medical therapy currently available. The underlying pathological mechanisms of TAD remain incompletely understood. In this study, we used a non-integrated episomal vector-based reprogramming system to generate induced pluripotent stem cells (iPSCs) from TAD patients and healthy controls. Both TAD and normal iPSCs expressed key pluripotency markers and were capable of differentiating into the three germ layers in vitro. These iPSCs were differentiated into VSMCs through a mesodermal intermediate for disease modeling. VSMCs derived from both TAD and normal iPSCs expressed smooth muscle -actin (-SMA), calponin, and SM22. However, TAD-iPSC-derived VSMCs exhibited significantly reduced contraction in response to carbachol stimulation compared to their normal counterparts. Whole-exome sequencing identified a mutation in the COL4A2 gene (c.392G>T, p. R131M) in TAD-iPSCs. This mutation was associated with reduced collagen IV expression and increased expression of collagen I and III in TAD-VSMCs, both with and without TGF-{beta} stimulation. Furthermore, noncanonical TGF-{beta} signaling was hyperactivated in TAD-VSMCs, accompanied by elevated MMP9 expression. This patient-specific iPSC model reveals key dysfunctions in VSMC contractility, extracellular matrix protein expression, and dysregulated TGF-{beta} signaling, which may contribute to TAD pathogenesis. Our findings provide new insights into the molecular mechanisms driving TAD and offer a platform for future therapeutic development.

pathology↗

bioRxiv2024

Human Neural Organoid Microphysiological Systems Show the Building Blocks Necessary for Basic Learning and Memory

Brain Microphysiological Systems including neural organoids derived from human induced pluripotent stem cells offer a unique lens to study the intricate workings of the human brain. This paper investigates the foundational elements of learning and memory in neural organoids, also known as Organoid Intelligence by quantifying immediate early gene expression, synaptic plasticity, neuronal network dynamics, and criticality to demonstrate the utility of these organoids in basic science research. Neural organoids showed synapse formation, glutamatergic and GABAergic receptor expression, immediate early gene expression basally and evoked, functional connectivity, criticality, and synaptic plasticity in response to theta-burst stimulation. In addition, pharmacological interventions on GABAergic and glutamatergic receptors, and input specific theta-burst stimulation further shed light on the capacity of neural organoids to mirror synaptic modulation and short-term potentiation, demonstrating their potential as tools for studying neurophysiological and neurological processes and informing therapeutic strategies for diseases. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=169 SRC="FIGDIR/small/613333v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@50a256org.highwire.dtl.DTLVardef@1d1f8c9org.highwire.dtl.DTLVardef@24688borg.highwire.dtl.DTLVardef@4ba3b4_HPS_FORMAT_FIGEXP M_FIG C_FIG Overview of the main components of the experiments conducted. Figure created using BioRender.com.

neuroscience↗

bioRxiv2024

Cross-Tissue Coordination between SLC Nucleoside Transporters Regulates Reproduction in Caenorhabditis elegans

Metabolism is fundamental to organism physiology and pathology. From the intricate network of metabolic reactions, diverse chemical molecules, collectively termed as metabolites, are produced. In multicellular organisms, metabolite communication between different tissues is vital for maintaining homeostasis and adaptation. However, the molecular mechanisms mediating these metabolite communications remain poorly understood. Here, we focus on nucleosides and nucleotides, essential metabolites involved in multiple cellular processes, and report the pivotal role of the SLC29A family of transporters in mediating nucleoside coordination between the soma and the germline. Through genetic analysis, we discovered that two Caenorhabditis elegans homologs of SLC29A transporters, Equilibrative Nucleoside Transporter ENT-1 and ENT-2, act in the germline and the intestine, respectively, to regulate reproduction. Their knockdown synergistically results in sterility. Further single-cell transcriptomic and targeted metabolomic profiling revealed that the ENT double knockdown specifically affects genes in the purine biosynthesis pathway and reduces the ratio of guanosine to adenosine levels. Importantly, guanosine supplementation into the body cavity/pseudocoelom through microinjection rescued the sterility caused by the ENT double knockdown, whereas adenosine microinjection had no effect. Together, these studies support guanosine as a rate limiting factor in the control of reproduction, uncover the previously unknown nucleoside/nucleotide communication between the soma and the germline essential for reproductive success, and highlight the significance of SLC-mediated cell-nonautonomous metabolite coordination in regulating organism physiology. Author SummaryMetabolism is essential for life, involving a complex network of chemical reactions that requires a well-organized system to maintain efficiency. This includes the optimal allocation of resources and the dynamic exchange of metabolic products between various compartments within an organism. Solute carriers (SLCs) are the largest family of transporters for metabolic products across the animal kingdom. In our research, we investigated how specific SLC transporters collaborate to move key metabolic products between different tissues. We identified two SLC transporters, Equilibrative Nucleoside Transporter ENT-1 and ENT-2, which are vital for transporting guanosine, a purine nucleoside, to support successful reproduction in the nematode Caenorhabditis elegans. We discovered that ENT-2 acts in the gut to export guanosine to the surrounding body cavity, while ENT-1 functions in the germline to import guanosine from the body cavity. When both transporters are disrupted, the animals experience significant reproductive defects. Our study underscores the importance of coordinated activity between SLC transporters in different tissues to maintain organism health. A breakdown in this communication can result in metabolic imbalances and physiological dysfunction.

genetics↗

bioRxiv2024

The CLIC/GEEC pathway regulates particle endocytosis and formation of the virus-containing compartment (VCC) in HIV-1-infected macrophages

HIV-1 particles are captured by the immunoglobulin superfamily member Siglec-1 on the surface of macrophages and dendritic cells, leading to particle internalization and facilitating trans-infection of CD4+ T cells. HIV-1-infected macrophages develop a unique intracellular compartment termed the virus-containing compartment (VCC) that exhibits characteristic markers of the late endosome and is enriched in components of the plasma membrane (PM). The VCC has been proposed as the major site of particle assembly in macrophages. Depleting Siglec-1 from macrophages significantly reduces VCC formation, implying a link between the capture and endocytosis of external HIV-1 particles and the development of VCCs within HIV-infected cells. We found that endocytosis of particles to the VCC was independent of clathrin, but required dynamin-2. CD98 and CD44, classical markers of the CLIC/GEEC pathway, colocalized with Siglec-1 and HIV-1 particles within the VCC. Inhibition of CLIC/GEEC-mediated endocytosis by chemical or genetic means resulted in the arrest of captured HIV-1 particles on the macrophage cell surface and prevented VCC formation. Virus-like particles (VLPs) were taken up within CD98 and Siglec-1-enriched tubular membranes that migrated centripetally over time to form VCC-like structures. These findings indicate that following capture of virus by Siglec-1, particles follow an endocytic route to the VCC that requires both the CLIC/GEEC pathway and dynamin-2. We propose a model in which internalization of HIV-1 particles together with CLIC/GEEC membranes leads to the formation of the VCC in HIV-infected macrophages, creating an intracellular platform that facilitates further particle assembly and budding. Author SummaryThe major cell types infected by HIV are CD4+ T cells and macrophages. Infection of macrophages is of great interest because this cell type can contribute to transmission of virus within tissues, and because infected macrophages contribute to HIV-related complications that include neurologic disorders, endocrine disorders, and cardiovascular disease. HIV infection of macrophages may also create a latent reservoir that persists in infected individuals despite administration of antiretroviral therapy. Here we focused on a compartment that forms in HIV-infected macrophages termed the virus-containing compartment or VCC. The VCC is an intracellular compartment that has been described as a site of assembly and as a holding compartment for viruses, and contains components of both intracellular organelles and the plasma membrane. We identified an endocytosis pathway that helps to explain the origins of the VCC, the CLIC/GEEC pathway. Inhibition of the CLIC/GEEC pathway prevented virus-like particle delivery to the VCC and prevented the VCC from forming in HIV-infected macrophages. The GTPase dynamin-2 was also required for delivery of HIV particles to the VCC. This study identifies a new facet of how HIV interacts with macrophages, suggesting that disruption of this pathway could be a therapeutic strategy with implications for HIV cure efforts.

microbiology↗

bioRxiv2024

Somatic mutation phasing and haplotype extension using linked-reads in multiple myeloma

Somatic mutation phasing informs our understanding of cancer-related events, like driver mutations. We generated linked-read whole genome sequencing data for 23 samples across disease stages from 14 multiple myeloma (MM) patients and systematically assigned somatic mutations to haplotypes using linked-reads. Here, we report the reconstructed cancer haplotypes and phase blocks from several MM samples and show how phase block length can be extended by integrating samples from the same individual. We also uncover phasing information in genes frequently mutated in MM, including DIS3, HIST1H1E, KRAS, NRAS, and TP53, phasing 79.4% of 20,705 high-confidence somatic mutations. In some cases, this enabled us to interpret clonal evolution models at higher resolution using pairs of phased somatic mutations. For example, our analysis of one patient suggested that two NRAS hotspot mutations occurred on the same haplotype but were independent events in different subclones. Given sufficient tumor purity and data quality, our framework illustrates how haplotype-aware analysis of somatic mutations in cancer can be beneficial for some cancer cases.

bioinformatics↗

bioRxiv2024

Secondary metabolites shape Streptomyces-Streptomyces interaction: Mass Spectrometry Imaging reveals lydicamycins broadly induce sporulation

Streptomyces are major players in soil microbiomes, however, interactions involving Streptomyces and other actinobacteria are rarely described. The complex developmental cycle of actinobacteria necessitates a multi-omics approach to unravel the web of information. This study resulted from the observation of induced morphogenesis between two environmental isolates from the same site, Kitasatospora sp. P9-2B1 and Streptomyces sp. P9-2B2. When co-cultivated on potato dextrose agar (PDA), P9-2B2 induced a wave-like sporulation in strain P9-2B1. Using mass spectrometry imaging, we revealed that a suite of lydicamycins were present in this induced sporulation zone. Lydicamycin deficient mutants were generated using CRISPR Base-Editing and the inducible sporulation ceased, confirming their role in triggering morphological differentiation. In agar diffusion assays, pure lydicamycin was inhibitory when added concurrently with bacterial inoculation and induced sporulation with delayed addition. Subsequent testing of additional environmental isolates resulted in the same inducible sporulation wave phenomenon, including Streptomyces coelicolor M145 and M1146. Using transcriptomics, we observed the differential expression of genes related to early aerial mycelium development four days into cocultivation and the transitional genes responsible for development of spores on day 9. Along with these differentially expressed genes, we also observed numerous overall stress responses, specifically cell envelope stress responses. These findings uncovered actinobacteria interactions mediated by lydicamycins, pointing to a potential role of certain groups of bioactive metabolites in nature. ImportanceShifting away from an antibiotic discovery mindset, uncovering the chemical ecology of secondary metabolites is key to maximizing their biotechnological application. The reduced complexity of dual cultures allows for in depth analysis and investigation of these interactions via multi-omics provides orthogonal data leading to more robust conclusions. This study provides insight into the role of lydicamycins in dual cultures with other actinobacteria and provides an integral roadmap for future chemical ecology work between microorganisms, especially through the use of mass spectrometry imaging.

ecology↗

bioRxiv2024

LINC01432 binds to CELF2 in newly diagnosed multiple myeloma promoting short progression-free survival to standard therapy

Multiple Myeloma (MM) is a highly prevalent and incurable form of cancer that arises from malignant plasma cells, with over 35,000 new cases diagnosed annually in the United States. While there are a growing number of approved therapies, MM remains incurable and nearly all patients will relapse and exhaust all available treatment options. Mechanisms for disease progression are unclear and in particular, little is known regarding the role of long non-coding RNAs (lncRNA) in mediating disease progression and response to treatment. In this study, we used transcriptome sequencing to compare newly diagnosed MM patients who had short progression- free survival (PFS) to standard first-line treatment (PFS < 24 months) to patients who had prolonged PFS (PFS > 24 months). We identified 157 differentially upregulated lncRNAs with short PFS and focused our efforts on characterizing the most upregulated lncRNA, LINC01432. We investigated LINC01432 overexpression and CRISPR/Cas9 knockdown in MM cell lines to show that LINC01432 overexpression significantly increases cell viability and reduces apoptosis, while knockdown significantly reduces viability and increases apoptosis, supporting the clinical relevance of this lncRNA. Next, we used individual-nucleotide resolution cross-linking immunoprecipitation with RT-qPCR to show that LINC01432 directly interacts with the RNA binding protein, CELF2. Lastly, we showed that LINC01432-targeted locked nucleic acid antisense oligonucleotides reduce viability and increases apoptosis. In summary, this fundamental study identified lncRNAs associated with short PFS to standard NDMM treatment and further characterized LINC01432, which inhibits apoptosis. Key points: lncRNA expression was found to be dysregulated in patients with short PFS to standard multiple myeloma therapy. LINC01432-bound CELF2 inhibits apoptosis.

cancer biology↗

bioRxiv2024

A gentle palette of plasma membrane dyes

Plasma membrane stains are one of the most important organelle markers for unambiguous assignments of individual cells and monitoring membrane morphology and dynamics. The state-of-the-art PM stains are bright, specific, fluorogenic, and compatible with super-resolution imaging. However, when recording membrane dynamics, particularly under light-intensive microscopes, PM is prone to photodynamic damages due to its phospholipid bilayer nature. Here we developed PK Mem dyes tailored for time-lapse fluorescence imaging. By integrating triplet-state quenchers into the MemBright dyes featuring cyanine chromophores and amphiphilic zwitterion anchors, PK Mem dyes exhibited a three-fold reduction in phototoxicity and a more than four-fold improvement in photostability in imaging experiments. These dyes enable 2D and 3D imaging of live or fixed cancer cell lines and a wide range of primary cells, at the same time pair well with various fluorescent markers. PK Mem dyes can be applied to neuronal imaging in brain slices and in vivo two-photon imaging. The gentle nature of PK Mem palette enables ultralong-term recording of cell migration and cardiomyocyte beating. Notably, PK Mem dyes are optically compatible with STED/SIM imaging, which can handily upgrade the routine of time-lapse neuronal imaging, such as growth cone tracking and mitochondrial transportations, into nanoscopic resolutions.

neuroscience↗

bioRxiv2024

Spirolactone, an unprecedented antifungal β-lactone spiroketal macrolide from Streptomyces iranensis

Fungal infections pose a great threat to public health and there are limited antifungal medicaments. Streptomyces is an important source of antibiotics, represented by the clinical drug amphotericin B. The rapamycin-producer Streptomyces iranensis harbors an unparalleled Type I polyketide synthase, which codes for a novel antifungal macrolide alligamycin A (1), the structure of which was confirmed by NMR, MS, and X-ray crystallography. Alligamycin A harbors an undescribed carbon skeleton with 13 chiral centers, featuring a ({beta}-lactone moiety, a [6,6]-spiroketal ring, and an unprecedented 7-oxo-octylmalonyl-CoA extender unit incorporated by a potential novel crotonyl-CoA carboxylase/reductase. The ali biosynthetic gene cluster was confirmed through CRISPR-based gene editing. Alligamycin A displayed profound antifungal effects against numerous clinically relevant filamentous fungi, including Talaromyces and Aspergillus species. ({beta}-Lactone ring is essential for the antifungal activity and alligamycin B (2) with disruption in the ring abolished the antifungal effect. Proteomics analysis revealed alligamycin A potentially disrupted the integrity of fungal cell walls and induced the expression of stress-response proteins in Aspergillus niger. Alligamycins represent a new class of potential drug candidate to combat fungal infections.

biochemistry↗

bioRxiv2024

The subthalamic nucleus contributes causally to perceptual decision-making in monkeys

The subthalamic nucleus (STN) plays critical roles in the motor and cognitive function of the basal ganglia (BG), but the exact nature of these roles is not fully understood, especially in the context of decision-making based on uncertain evidence. Guided by theoretical predictions of specific STN contributions, we used single-unit recording and electrical microstimulation in the STN of healthy monkeys to assess its causal, computational roles in visual-saccadic decisions based on noisy evidence. The recordings identified subpopulations of STN neurons with distinct task-related activity patterns that related to different theoretically predicted functions. Microstimulation caused changes in behavioral choices and response times that reflected multiple contributions to an "accumulate-to-bound"-like decision process, including modulation of decision bounds and evidence accumulation, and to non-perceptual processes. These results provide new insights into the multiple ways that the STN can support higher brain function.

neuroscience↗

bioRxiv2024

Defective Homologous Recombination and Genomic Instability Predict Increased Responsiveness to Carbon Ion Radiotherapy in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is inherently resistant to conventional chemo-and radiation-therapy. However, clinical trials showed that carbon ion radiotherapy (CIRT) with concurrent gemcitabine can be effective for treating unresectable locally advanced PDAC. In this study, we aimed to determine features that could identify patients who would benefit most from CIRT. A panel of human PDAC cell lines with various genetic backgrounds was leveraged to determine whether a subset could be identified that preferentially responds to CIRT. The cell lines displayed a differential response to CIRT as compared to {gamma}-rays as measured by relative biological effectiveness (RBE) calculated at 10% survival, which ranged from 1.96 to 3.04. Increased radiosensitivity correlated with decreased DNA double strand break (DSB) repair as measured by {gamma}H2AX foci resolution. We determined that the cell lines most sensitive to CIRT are defective in the homologous recombination (HR) DSB repair pathway and/or have high genomic instability due to elevated replication stress. Next, this knowledge was utilized to assess whether the HR pathway could be targeted to potentiate CIRT in vitro. It was determined that pretreating a radioresistant PDAC cell line with the HR inhibitor, B02, resulted in a marked increase in sensitivity to CIRT when treated with high linear energy transfer (LET) radiation in the spread-out Bragg peak (74.1-89.3 keV/m) but not at the entry LET (13.0-16.4 keV/m) in vitro as opposed to that seen with a NHEJ inhibitor. These data suggest a greater therapeutic index with the combination therapy in the tumor over normal tissues based on LET distribution. These data support the notion that PDAC tumors with defects in HR and/or those with high inherent replication stress respond to CIRT without the concern for excessive normal tissue toxicity. With the advent of agents targeting HR, the difference in tumor cell response in the entry region vs within the SOBP based upon the respective LETs of those regions of the beam profile, will be superior to agents that target NHEJ.

cancer biology↗