Biology subjects

Yu, X.

Publications and source records attributed to Yu, X..

At least 307 records · Page 17Linked to original sources

bioRxiv2023

The Effect of Electrical Resonance in Neurons upon the Instability of Electrical Nerve Stimulations

Repetitive electrical nerve stimulation can induce a long-lasting perturbation of the axons membrane potential, resulting in unstable stimulus-response relationships. Despite being observed in electrophysiology, the precise mechanisms underlying stimulus-induced instability is still an open question due to the lack of a proper theoretical model. This study proposes a new method based on a Circuit-Probability theory to reveal the interlinkages between the electrical resonance of neurons and the instability of neural response. Supported by in vivo investigations, this new model predicts several key characteristics of stimulus-induced instability and proposes a stimulation method to minimize the instability. This model provides a powerful tool to improve our understanding of the interaction between the external electric field and the complexity of the biophysical characteristics of axons.

neuroscience↗

bioRxiv2023

Histone acetylation insulator SET orchestrates PP2A inhibition and super-enhancer activation

Wide-spread growth-essential genes are hyper-transcribed in the pancreatic cancer cells. Searching for the factors that reprogram this abnormal transcription, we identified the nuclear oncogene SET that supported CDK9-induced and Pol II-mediated transcription. SET disrupted PP2A-A/C interaction via its C-terminal domains. Through blocking PP2A activity, SET assisted CDK9 to maintain Pol II CTD phosphorylation and activated mRNA transcription. Meanwhile, as a histone acetylation insulator, SET mainly suppressed histone acetylation in the gene promoters but evaded enhancers. Massive super-enhancer associated genes, including the oncogene MET, were hence permitted to be transcribed by SET over-expression. Our findings position SET as a key factor that bridges histone acetylation and PP2A related transcription in cancer cells.

molecular biology↗

bioRxiv2023

Tracking the PROTAC degradation pathway in living cells highlights the importance of ternary complex measurement for PROTAC optimization

The multistep PROTAC (PROteolysis TArgeting Chimeras) degradation process poses challenges for their rational development, as rate limiting steps determining PROTAC efficiency remain largely unknown. Moreover, the slow throughput of currently used endpoint assays does not allow the comprehensive analysis of larger series of PROTACs. Here we developed cell-based assays using NanoLuciferase and HaloTags, that allow measuring PROTAC induced degradation and ternary complex formation kinetics and stability in cells. Using PROTACs developed for degradation of WDR5, the characterization of the mode of action of these PROTACs in the early degradation cascade revealed a key role of ternary complex formation and stability. Comparing a series of ternary complex crystal structures highlighted the importance of an efficient E3-target interface for ternary complex stability. The developed assays outline a strategy for the rational optimization of PROTACs using a series of live cell assays monitoring key steps of the early PROTAC induced degradation pathway. SignificanceThe multistep PROTAC induced degradation process of a POI poses a significant challenge for the rational design of these bifunctional small molecules as critical steps that limit PROTAC efficacy cannot be easily assayed at required throughput. In addition, the cellular location of the POI may pose additional challenges as some cellular compartments, such as the nucleus, may not be easily reached by PROTAC molecules and the targeted E3 ligases may not be present in this cellular compartment. We propose therefore a comprehensive assay panel for PROTACs evaluation in cellular environments using a sensor system that allows continuous monitoring of the protein levels of the endogenous POI. We developed a cell line expressing WDR5 from its endogenous locus in fusion with a small sequence tag (HiBIT) that can be reconstituted to functional NanoLuciferase (NLuc). This system allowed continuous monitoring of endogenous WDR5 levels in cells and together with HaloTag system also the continuous monitoring of ternary complex (E3, WDR5 and PROTAC) formation. As this assay can be run at high throughput, we used this versatile system monitoring three diverse chemical series of WDR5 PROTACs that markedly differ in their degradation properties. Monitoring cell penetration, binary complex formation (PROTAC-WDR5 and PROTAC-VHL) as well as ternary complex formation we found that PROTAC efficiency highly correlated with synergy of ternary complex formation in cells. This study represents a first data set on diverse PROTACs studying this property in cellulo and it outlines a strategy for the rational optimization of PROTACs. It also provided kinetic data on ternary complex assembly and dissociation that may serve as a benchmark for future studies utilizing also kinetic properties for PROTAC development. Comparative structural studies revealed larger PROTAC mediated interaction surfaces for PROTACs that efficiently formed ternary complexes highlighting the utility of structure based optimization of PROTAC induced ternary complexes in the development process.

molecular biology↗

bioRxiv2023

Humanized CD36 mouse model supports the preclinical evaluation of therapeutic candidates targeting CD36

CD36 (also known as scavenger receptor B2) is a multifunctional receptor that mediates lipid uptake, advanced oxidation protein products, and immunological recognition, and has roles in lipid accumulation, apoptosis, as well as in metastatic colonization in cancer. CD36 is involved in tumor immunity, metastatic invasion, and therapy resistance through various molecular mechanisms. Targeting CD36 has emerged as an effective strategy for tumor immunotherapy. In this study, we have successfully generated a novel CD36 humanized mouse strain where the sequences encoding the extracellular domains of the mouse Cd36 gene were replaced with the corresponding human sequences. The results showed that CD36 humanized mice expressed only human CD36, and the proportion of each lymphocyte was not significantly changed compared with wild-type mice. Furthermore, CD36 monoclonal antibody could significantly inhibit tumor growth after treatment. Therefore, the CD36 humanized mice provided a validated preclinical mouse model for the evaluation of tumor immunotherapy targeting CD36.

immunology↗

bioRxiv2023

Regulated Induced Proximity Targeting Chimeras (RIPTACs): a Novel Heterobifunctional Small Molecule Therapeutic Strategy for Killing Cancer Cells Selectively

While specific cell signaling pathway inhibitors have yielded great success in oncology, directly triggering cancer cell death is one of the great drug discovery challenges facing biomedical research in the era of precision oncology. Attempts to eradicate cancer cells expressing unique target proteins, such as antibody-drug conjugates (ADCs), T-cell engaging therapies, and radiopharmaceuticals have been successful in the clinic, but they are limited by the number of targets given the inability to target intracellular proteins. More recently, heterobifunctional small molecules such as Proteolysis Targeting Chimera (PROTACs) have paved the way for protein proximity inducing therapeutic modalities. Here, we describe a proof-of-concept study using novel heterobifunctional small molecules called Regulated Induced Proximity Targeting Chimeras or RIPTACs, which elicit a stable ternary complex between a target protein selectively expressed in cancer tissue and a pan-expressed protein essential for cell survival. The resulting cooperative protein:protein interaction (PPI) abrogates the function of the essential protein, thus leading to cell death selectively in cells expressing the target protein. This approach not only opens new target space by leveraging differentially expressed intracellular proteins but also has the advantage of not requiring the target to be a driver of disease. Thus, RIPTACs can address non-target mechanisms of resistance given that cell killing is driven by inactivation of the essential protein. Using the HaloTag7-FKBP model system as a target protein, we describe RIPTACs that incorporate a covalent or non-covalent target ligand connected via a linker to effector ligands such as JQ1 (BRD4), BI2536 (PLK1), or multi-CDK inhibitors such as TMX3013 or dinaciclib. We show that these RIPTACs exhibit positive co-operativity, accumulate selectively in cells expressing HaloTag7-FKBP, form stable target:RIPTAC:effector trimers in cells, and induce an anti-proliferative response in target-expressing cells. We propose that RIPTACs are a novel heterobifunctional therapeutic modality to treat cancers that are known to selectively express a specific intracellular protein.

cancer biology↗

bioRxiv2022

Biphasic curvature-dependence of cell migration inside microcylinders: persistent randomness versus directionality

Cell-scale curvature plays important roles in controlling cell and tissue behaviors. However, these roles have not been well quantified, and the underlying mechanisms remain elusive. We combine experiments with theory to study systematically the curvature-dependence of cell migration inside PDMS microcylinders. We find that persistence is positively correlated with speed, following the universal speed-persistence coupling relation, i.e., faster cells turn less. Cell migration inside microcylinders is anisotropic and depends on curvature in a biphasic manner. At small curvatures, as curvature increases, the average speed and anisotropy both increase, but surprisingly, the average persistence decreases. Whereas as the curvature increases over some threshold, cells detach from the surface, the average speed and anisotropy both decrease sharply but the average persistence increases. Moreover, interestingly, cells are found to leave paxillins along their trajectories (on curved but not planar surfaces), facilitating the assembly of focal adhesions of following cells. We propose a minimal model for the biphasic curvotaxis based on three mechanisms: the persistent random "noise", the bending penalty of stress fibers, and the cell-surface adhesion. The findings provide a novel and general perspective on directed cell migration in the widely existing curved microenvironment of cells in vivo.

biophysics↗

bioRxiv2022

Changes of platelet morphology, ultrastructure and function in patients with acute ischemic stroke based on super-resolution microscopy.

Platelets are important in acute ischemic stroke (AIS) thrombosis. The observation and evaluation of platelet ultrastructure and efficacy of antiplatelet drug in AIS patients is difficult due to microscopic limitations and sensitivity of platelet. The new super-resolution microscope (SIM) can accurately, quickly analyze the platelet ultrastructure and antiplatelet drug in AIS patients. We applied SIM to observe the morphology and ultrastructure of platelets with AIS patients in different state. SIM images were analyzed to specify the dense granules and granules change of platelets in AIS patients. Testing platelet factor 4 (PF4) to reflect platelet releasing function. We observed that platelet activation in AIS patients was greater after stimulation, with granule showing a pattern of parenchymatous masses. SIM images analyzing showed diameter of platelets, average size of granules, area% of granules per field and mean area of granules per platelet in AIS patient were lower than healthy people. Platelet releasing function was suppressed at rest stage and more efficacy release after stimulation. 2MeSamp inhibited parenchymatous masses of granules and reduced PF4 release of platelets after stimulation. According to the results, the structure and function of platelets in AIS patients are indeed altered. Additionally, SIM could be used as a new method to indicates the onset of AIS and assess antiplatelet drugs.

cell biology↗

bioRxiv2022

A compendium of genetic regulatory effects across pig tissues

The Farm animal Genotype-Tissue Expression (FarmGTEx, https://www.farmgtex.org/) project has been established to develop a comprehensive public resource of genetic regulatory variants in domestic animal species, which is essential for linking genetic polymorphisms to variation in phenotypes, helping fundamental biology discovery and exploitation in animal breeding and human biomedicine. Here we present results from the pilot phase of PigGTEx (http://piggtex.farmgtex.org/), where we processed 9,530 RNA-sequencing and 1,602 whole-genome sequencing samples from pigs. We build a pig genotype imputation panel, characterize the transcriptional landscape across over 100 tissues, and associate millions of genetic variants with five types of transcriptomic phenotypes in 34 tissues. We study interactions between genotype and breed/cell type, evaluate tissue specificity of regulatory effects, and elucidate the molecular mechanisms of their action using multi-omics data. Leveraging this resource, we decipher regulatory mechanisms underlying about 80% of the genetic associations for 207 pig complex phenotypes, and demonstrate the similarity of pigs to humans in gene expression and the genetic regulation behind complex phenotypes, corroborating the importance of pigs as a human biomedical model.

genomics↗

bioRxiv2022

Rapid iPSC inclusionopathy models shed light on formation, consequence and molecular subtype of alpha-synuclein inclusions

Intracellular inclusions accompanying neurodegeneration are histopathologically and ultrastructurally heterogeneous but the significance of this heterogeneity is unclear. iPSC models, while promising for disease modeling, do not form inclusions in a reasonable timeframe and suffer from limited tractability. Here, we developed an iPSC toolbox utilizing piggyBac-based or targeted transgenes to rapidly induce CNS cells with concomitant expression of aggregation-prone proteins. This system is amenable to screening and longitudinal tracking at single-cell and single-inclusion resolution. For proof-of-principle, cortical neuron -synuclein "inclusionopathy" models were engineered to form inclusions through exogenous seeding or -synuclein mutation. These models recapitulated known fibril- and lipid-rich inclusion subtypes, uncovering dynamic interactions between them, and refined the classification of inclusions in postmortem brain. Genetic-modifier and protein-interaction screens pinpointed proteins like RhoA whose sequestration into specific inclusion subtypes is likely to be toxic. This iPSC platform should enhance our understanding of proteinaceous pathologies in neurodegeneration and facilitate therapeutics development.

neuroscience↗

bioRxiv2022

Molecular basis of ligand-dependent Nurr1-RXRα activation

Small molecule compounds that activate transcription of Nurr1-RXR (NR4A2-NR2B1) nuclear receptor heterodimers are implicated in the treatment of neurodegenerative disorders, but function through poorly understood mechanisms. Here, we show that RXR ligands activate Nurr1-RXR through a mechanism that involves ligand-binding domain (LBD) heterodimer proteinprotein interaction (PPI) inhibition, a paradigm distinct from classical pharmacological mechanisms of ligand-dependent nuclear receptor modulation. NMR spectroscopy, protein-protein interaction, cellular transcription assays show that Nurr1-RXR transcriptional activation by RXR ligands is not correlated with classical RXR agonism but instead correlated with weakening Nurr1-RXR LBD heterodimer affinity and heterodimer dissociation. Our data inform a model by which pharmacologically distinct RXR ligands (agonists and Nurr1-RXR selective agonists that function as RXR antagonists) operate as allosteric PPI inhibitors that release a transcriptionally active Nurr1 monomer from a repressive Nurr1-RXR heterodimeric complex. These findings provide a molecular blueprint for ligand activation of Nurr1 transcription via small molecule targeting of Nurr1-RXR.

biochemistry↗

bioRxiv2022

Size-Dependent Transport of Cerebrospinal Fluid Tracers in Mouse Brain Observed by Dynamic Contrast-Enhanced MRI

Recent studies have suggested the glymphatic system as a key mechanism of waste removal in the brain. Dynamic contrast-enhanced MRI (DCE-MRI) using intracisternally administered contrast agents is a promising tool for assessing glymphatic function in the whole brain. In this study, we evaluated the transport kinetics and distribution of three MRI contrast agents with vastly different molecular sizes in mice. Our results demonstrate that oxygen-17 enriched water (H217O), which has direct access to parenchymal tissues via aquaporin-4 water channels, exhibited significantly faster and more extensive transport compared to the two gadolinium-based contrast agents (Gd-DTPA and GadoSpin). Time-lagged correlation and clustering analyses also revealed different transport pathways for Gd-DTPA and H217O. Furthermore, there were significant differences in transport kinetics of the three contrast agents to the lateral ventricles, reflecting the differences in forces that drive solute transport in the brain. These findings suggest the size-dependent transport pathways and kinetics of intracisternal contrast agents and the potential of DCE-MRI for assessing multiple aspects of solute transport in the glymphatic system.

neuroscience↗

bioRxiv2022

Single-cell transcriptomics reveals subset-specific metabolic profiles underpinning the bronchial epithelial response to flagellin

Respiratory epithelial cells line the airways and represent the first line of defense against respiratory pathogens. The cellular heterogeneity of the airway wall has only recently been recognized by single-cell analyses. Here, we leveraged single-cell RNA sequencing of primary human bronchial epithelial cells growing in air-liquid interface to determine cell-specific changes evoked by flagellin, a protein driving the motility of many mucosal pathogens. We detected seven cell clusters in the human epithelium, including ciliated cells, ionocytes and several states of basal and secretory cells, of which only inflammatory basal cells and inflammatory secretory cells showed a proportional increase in response to flagellin. Only inflammatory secretory cells showed evidence of metabolic reprogramming toward aerobic glycolysis, and inhibition of the mTOR pathway specifically reduced this subset, prevented this metabolic shift, and reduced inflammatory gene transcription in these cells. This study expands our knowledge of the airways immune response to flagellated pathogens to single cell resolution and defines a novel target to modulate mucosal immunity during bacterial infections.

immunology↗

bioRxiv2022

Chinese fir genome and the evolution of gymnosperms

Seed plants comprise angiosperms and gymnosperms. The latter includes gnetophytes, cycads, Ginkgo, and conifers. Conifers are distributed worldwide, with 630 species distributed across eight families and 70 genera. Their distinctiveness has triggered much debate on their origin, evolution, and phylogenetic placement among seed plants. To better understand the evolution of gymnosperms and their relation to other seed plants, we report here a high-quality genome sequence for a tree species, Chinese fir (Cunninghamia lanceolata), which has excellent timber quality and high aluminum adaptability and is a member of Cupressaceae with high levels of heterozygosity. We assembled an 11.24 Gb genome with a contig N50 value of 2.15 Mb and anchored the 10.89 Gb sequence to 11 chromosomes. Phylogenomic analyses showed that cycads sister to Ginkgo, which place to sister in all gymnosperm lineages, and Gnetales within conifers sister to Pinaceae. Whole-genome duplication (WGD) analysis showed that the ancestor of seed plants has differentiated into angiosperms and gymnosperms after having experienced a WGD event. The ancestor of extant gymnosperm has experienced a gymnosperm-specific WGD event and the extant angiosperms do not share a common WGD before their most recent common ancestor diverged into existing angiosperms lineages. Analysis of the MADS-box gene family of C. lanceolata revealed the developmental mechanism of the reproductive organs in C. lanceolata, which supported the (A)B(C) model of the development of gymnosperms reproductive organs. In addition, astringent seeds and shedding of whole branches (with withered leaves) might be a strategy of C. lanceolata that evolved during long-term adaptation to an aluminum-rich environment. The findings also reveal the molecular regulation mechanism of shade tolerance in C. lanceolata seedlings. Our results improve the resolution of ancestral genomic features within seed plants and the knowledge of genome evolution and diversification of gymnosperms.

genomics↗

bioRxiv2022

Conventional dendritic cells 2, the targeted antigen-presenting-cell, induces enhanced type 1 immune responses in mice immunized with CVC1302 in oil formulation

Multifunctional CD4+ T helper 1 (Th1) cells, producing IFN-{gamma}, TNF- and IL-2, define a correlate of vaccine-mediated protection against intracellular infection. In our previous study, we found that CVC1302 in oil formulation promoted the differentiation of IFN-{gamma}+/TNF-+/IL-2+ Th1 cells. In order to extend the application of CVC1302 in oil formulation, this study aimed to elucidate the mechanism of action in improving the Th1 immune response. Considering the signals required for the differentiation of CD4+ T cells to Th1 cells, we detected the distribution of innate immune cells and the model antigen OVA-FITC in lymph node (LN), as well as the quantity of cytokines produced by the innate immune cells. The results of these experiments show that, cDC2 and OVA-FITC localized to inter-follicular region (IFR) of the draining lymph nodes, inflammatory monocytes localized to both IFR and T cell zone, which mainly infiltrate from the blood. In this inflammatory niche within LN, CD4+ T cells were attracted into IFR by CXCL10, secreting by inflammatory monocytes, then activated by IL-12-secreting cDC2. Above all, CVC1302 in oil formulation, on the one hand, targeted antigen and inflammatory monocyte into the LN IFN in order to attract CD4+ T cells, on the other hand, targeted cDC2 to produce IL-12 in order to promote optimal Th1 differentiation. The new finding will provide a blueprint for application of immunopotentiators in optimal formulations. ImportanceAlong with the development of veterinary immunology, immunopotentiator and delivery system were not simply mixed with antigen, more and more attentions paid on the optimal compatibility in order to induce multifunctional immune responses. As reported, LPS formulated in IFA targeted antigens to the IFR of the LN, and recruited Mo into the IFR, then attracted antigen-specific CD4+ T cells, which differentiated into Th1 cells under the IL-12 produced by DC-SIGN+ DC(1). Herein, we further found that CVC1302 formulated with Marcol 52 induced enhanced Th1 immunity. Combined with our previous finding that CVC1302 in oil formulation induced improved humoral immunity, we concluded that CVC1302 in oil formulation provided multifunctional immunity, not only higher antibody titers to prevent pathogen infection, but also cellular immunity cytokine to prevent viral shedding.

immunology↗

bioRxiv2022

Regulation of adventitial interstitial fluid circulation by heartbeat and respiration

Converging studies showed interstitial fluid (ISF) adjacent to blood vessels flows along adventitia of vasculature into heart and lungs. We aim to reveal circulatory pathways and regulatory mechanism of such adventitial ISF flow in rat model. By MRI, real-time fluorescent imaging, micro-CT and histological analysis, ISF was found to flow in adventitial matrix surrounded by fascia and along systemic vessels into heart, then flow into lungs via pulmonary arteries and back to heart via pulmonary veins, which was neither perivascular tissues nor blood or lymphatic vessels. Under physiological conditions, speckle-like adventitial ISF flow rate was positively correlated with heart rate, increased when holding breath, became pulsative during heavy breathing. During cardiac or respiratory cycle, each dilation or contraction of heart or lungs can generate to-and-fro adventitial ISF flow along femoral veins. Discovered regulatory mechanisms of adventitial ISF flow along vasculature by heart and lungs will revolutionize understanding of cardiovascular system. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=159 SRC="FIGDIR/small/512678v3_ufig1.gif" ALT="Figure 1"> View larger version (68K): org.highwire.dtl.DTLVardef@1d29c16org.highwire.dtl.DTLVardef@583f5org.highwire.dtl.DTLVardef@1a551eorg.highwire.dtl.DTLVardef@ca4780_HPS_FORMAT_FIGEXP M_FIG Graphic abstract of adventitial interstitial fluid cycle by heartbeat and respiration.The heart and lungs can work together to regulate the ISF (green arrow) adjacent to blood vessels to flow centripetally in an adventitial pathway along the major arteries and veins of the systemic vasculature to the epicardium and myocardium, then flow into the lungs via the pulmonary arteries and back to the heart via the pulmonary veins, forming an adventitial ISF circulatory network. Under physiological conditions, the speckle-like adventitial ISF flow rate was positively correlated with heart rate, increased when holding breath, and became pulsative during heavy breathing. During respiratory cycle, each expansion of the lungs during inflation generates a centrifugal flow of adventitial ISF along the systemic veins, while each contraction of the lungs during deflation generates a centripetal adventitial ISF flow. During cardiac cycle, each dilation of atria or ventricles generates a centripetal flow of adventitial ISF along the systemic veins, while each contraction of atria or ventricles generates a centrifugal adventitial ISF flow. C_FIG

physiology↗

bioRxiv2022

Development of an affinity-enhanced clinical candidate TCR targeting NY-ESO-1 with optimal potency and high specificity

The clinical success of T-cell receptor (TCR)-based immunotherapy depends on the efficacy and specificity of TCRs. Naturally occurring TCRs have limited anti-tumor potency due to their low affinity for tumor antigens. Affinity enhancement is a promising strategy to generate highly potent TCRs. However, it is concerned that affinity-enhanced TCRs are prone to lose specificity. We isolated low affinity TCRs specific for NY-ESO-1157-165/HLA-A*02:01 from peripheral blood mononuclear cells of healthy donors. An affinity-enhanced TCR candidate with optimal affinity and specificity was generated using phage display and an extensive set of in vitro and in vivo assays. Alanine scanning mutagenesis showed that the TCR candidate retained specificity by making extensive contacts to the side chains of NY-ESO-1157-165 peptide. Adoptive transfer of T cells engineered with this candidate (termed TAEST16001) significantly inhibited tumor growth in subcutaneous, metastatic, and patient-derived xenograft (PDX) mouse tumor models. This study demonstrates that sophisticated engineering and screening techniques can be utilized to generate a clinical candidate TCR with potent anti-tumor activity without losing specificity. TAEST16001 was approved by the Center for Drug Evaluation (CDE) as the first TCR-based immunotherapy clinical trial in China (ClinicalTrials.gov Identifier: NCT03159585).

immunology↗

bioRxiv2022

Novel inductively-coupled ear-bars (ICEs) for fMRI signal enhancement in rat entorhinal cortex

Entorhinal cortex (EC) is a potential target of deep brain stimulation in Alzheimers disease (AD) and fMRI can enable whole-brain dynamic mapping noninvasively. However, it remains challenging to study EC-based fMRI connectivity in rodents due to image signal loss and the lower sensitivity of the surface coil ring or array coil for deep brain areas. To reduce the magnetic susceptibility artifacts driven signal loss issue, we introduced baby cream into the middle ear. To improve detection sensitivity, we implemented novel inductively-coupled ear-bars (ICEs) in the 7 T Bruker scanner, which resulted in an approximately 2-fold signal-to-noise ratio (SNR) increase in EC over the conventional surface array. The ICE can be conveniently utilized as an add-on device, with no modulation to the scanner interface. To demonstrate the applicability of ICEs for both task and resting-state (rs) fMRI, whole-brain echo-planar imaging (EPI) was performed in anesthetized rats modeling AD mixed dementia. Seed-based rs-fMRI connectivity maps emanating from the left entorhinal cortex demonstrated its connectivity to the hippocampus, piriform cortex, septal nuclei, and prefrontal cortex. Hence, this work demonstrates an optimized procedure for ICE by acquiring large scale networks emanating from a seed region that was not easily accessible by conventional MRI detectors, enabling better observation of EC-based brain fMRI connectivity studies with a higher signal-to-noise ratio in rodent models of dementia.

neuroscience↗

bioRxiv2022

Loss of ZNF251 stimulates NHEJ resulting in PARP inhibitor resistance in BRCA1-mutated cancer cells

Poly (ADP-ribose) polymerase inhibitors (PARPis) represent a promising new class of agents that have demonstrated efficacy in treating various cancers, particularly those with BRCA1/2 mutations. Cancer-associated BRCA1/2 mutations disrupt DNA double-strand break (DSB) repair by homologous recombination (HR). PARP inhibitors (PARPis) have been used to trigger synthetic lethality in BRCA1/2-mutated cancer cells by promoting the accumulation of toxic DSBs. Unfortunately, resistance to PARPis is common and can occur through multiple mechanisms, including the restoration of HR and/or stabilization of replication forks. To gain a better understanding of the mechanisms underlying PARPis resistance, we conducted an unbiased CRISPR-pooled genome-wide library screen to identify new genes whose deficiency confers resistance to the PARPi olaparib. Our research revealed that haploinsufficiency of the ZNF251 gene, which encodes zinc finger protein 251, is associated with resistance to PARPis in various breast and ovarian cancer cell lines carrying BRCA1 mutations. Mechanistically, we discovered that ZNF251 haploinsufficiency leads to stimulation of RAD51-mediated HR repair of DSBs in olaparib-treated BRCA1-mutated cancer cells. Moreover, we demonstrated that a RAD51 inhibitor reversed PARPi resistance in ZNF251 haploinsufficient cancer cells harboring BRCA1 mutations. Our findings provide important insights into the mechanisms underlying PARPis resistance by highlighting the role of RAD51 in this phenomenon.

cancer biology↗