Biology subjects

Chen, C.-Y.

Publications and source records attributed to Chen, C.-Y..

At least 55 records · Page 3Linked to original sources

bioRxiv2023

Genetic Diversity and Structural Complexity of the Killer-Cell Immunoglobulin-Like Receptor Gene Complex: A Comprehensive Analysis using Human Pangenome Assemblies

The killer-cell immunoglobulin-like receptor (KIR) gene complex, a highly polymorphic region of the human genome that encodes proteins involved in immune responses, poses strong challenges in genotyping due to its remarkable genetic diversity and structural intricacy. Accurate analysis of KIR alleles, including their structural variations, is crucial for understanding their roles in various immune responses. Leveraging the high-quality genome assemblies from the Human Pangenome Reference Consortium (HPRC), we present a novel bioinformatic tool, the Structural KIR annoTator (SKIRT), to investigate gene diversity and facilitate precise KIR allele analysis. We applied SKIRT on 47 HPRC-phased assemblies and identified a recurrent novel KIR2DS4/3DL1 fusion gene in the paternal haplotype of HG02630 and maternal haplotype of NA19240. Additionally, SKIRT accurately identifies eight structural variants and 17 novel nonsynonymous alleles, all of which were independently validated using short-read data or quantitative polymerase chain reaction. Our study has discovered a total of 570 novel alleles, among which eight haplotypes harbor at least one KIR gene duplication, six haplotypes have lost at least one framework gene, and 75 out of 94 haplotypes (79.8%) carry at least five novel alleles, thus confirming KIR genetic diversity. These findings are pivotal in providing insights into KIR gene diversity and serve as a solid foundation for understanding the functional consequences of KIR structural variations. High-resolution genome assemblies offer unprecedented opportunities to explore polymorphic regions that are challenging to investigate using short-read sequencing methods. The SKIRT pipeline emerges as a highly efficient tool, enabling the comprehensive detection of the complete spectrum of KIR alleles within human genome assemblies.

genomics↗

bioRxiv2023

Annotation-Free Deep Learning for Predicting Gene Mutations from Whole Slide Images of Acute Myeloid Leukemia

The rapid development of deep learning in recent years has revolutionized the field of medical image processing, including the applications of using high-resolution whole slide images (WSIs) in acute myeloid leukemia (AML) diagnosis. Although the potential of characterizing gene mutations directly from WSIs has been demonstrated in some cancers, it still faces challenges due to image resolutions and manual annotations. To address this, we propose a deep learning model based on multiple instance learning (MIL) with ensemble learning to predict gene mutations from AML annotation-free WSIs. Our deep learning model offers a promising solution for gene mutation prediction on NPM1 mutations and FLT3 -ITD without the need for patch-level or cell-level manual annotations, reducing the manpower and time costs associated with traditional supervised learning approaches. The dataset of 572 WSIs from AML patients that we used to train our MIL models is currently the largest independent database with both WSI and genetic mutation information. By leveraging upsampling and ensemble learning techniques, our final model achieved an AUC of 0.90 for predicting NPM1 mutations and 0.81 for FLT3 -ITD. This confirms the feasibility of directly obtaining gene mutation data through WSIs without the need for expert annotation and training involvement. Our study also compared the proportional representation of cell types before and after applying the MIL model, finding that blasts are consistently important indicators for gene mutation predictions, with their proportion increasing in mutated WSIs and decreasing in non-mutated WSIs after MIL application. These enhancements, leading to more precise predictions, have brought AML WSI analysis one step closer to being utilized in clinical practice.

bioinformatics↗

bioRxiv2023

Somatic mutation detection workflow validity distinctly influences clinical decision.

Evaluating robustness of somatic mutation detections is essential when utilizing whole exome sequencing (WES) for treatment decision-making. A comprehensive evaluation was conducted using tumor WES from the FDA-led Sequencing Quality Control Phase 2 (SEQC2) project, in which multiple library kits sequenced identical DNA materials across three labs to benchmark analytical validity. These workflows included various read aligner (BWA, Bowtie2, DRAGEN-Aligner, DRAGMAP, and HISAT2) and mutation caller (Mutect2, TNscope, DRAGEN-Caller, and DeepVariant) combinations. The results revealed that DRAGEN exhibited superior performance, achieving mean F1-scores of 0.966 and 0.791 for SNV and INDEL detection, respectively. Among open-source software, BWA Mutect2 and HISAT2 Mutect2 combinations showed the highest mean F1-scores for SNV (0.949) and IN-DEL (0.722), respectively. The analyses indicated that high-quality data can be analyzed as having worse results, and vice versa. Evaluations of COSMIC reported mutations unveiled discrepancies across enrichment kits. IDT enrichment kits showed a higher false negative rate, while Agilent WES kits tended to miss mutations in CBL and IDH1, and Roche library kits tended to miss the mutations in PIK3CB. For drug-related biomarkers, Sentieon TNscope tended to underestimate tumor mutation burden and overlook crucial drug-resistance mutations such as FLT3 (c.G1879A: p.A627T) for cytarabine resistance in leukemia and MAP2K1 (c.G199A:p.D67N) for BRAF inhibitors in melanoma. The findings highlight the importance of robust bioinformatic analysis in identifying tumor mutations and guiding clinical decision-making. HighlightsO_LIMutation callers had a significantly higher effect on overall sensitivity than aligners. C_LIO_LIBenchmarking analyses demonstrated that high-quality sequencing reads can be analyzed as having worse results, and vice versa. C_LIO_LIDRAGEN exhibited the best performance among other aligner-caller combinations. C_LIO_LIThe combination of BWA with Mutect2 and HISAT2 with Mutect2 yielded the highest mean F1 scores for detecting SNVs and INDELs by open-source software, respectively. C_LIO_LISentieon TNscope tended to underestimate the tumor mutation burden and missed several drug-resistant mutations. C_LI

bioinformatics↗

bioRxiv2023

Redox Active Plant Phenolic, Acetosyringone, for Electrogenetic Signaling

Redox is a unique, programmable modality capable of bridging communication between biology and electronics. Previous studies have shown that the E. coli redox-responsive OxyRS regulon can be re-wired to accept electrochemically generated hydrogen peroxide (H2O2) as an inducer of gene expression. Here we report that the redox-active phenolic plant signaling molecule acetosyringone (AS) can also induce gene expression from the OxyRS regulon. AS must be oxidized, however, as the reduced state present under normal conditions cannot induce gene expression. Thus, AS serves as a "pro-signaling molecule" that can be activated by its oxidation - in our case by application of oxidizing potential to an electrode. We show that the OxyRS regulon is not induced electrochemically if the imposed electrode potential is in the mid-physiological range. Electronically sliding the applied potential to either oxidative or reductive extremes induces this regulon but through different mechanisms: reduction of O2 to form H2O2 or oxidation of AS. Fundamentally, this work reinforces the emerging concept that redox signaling depends more on molecular activities than molecular structure. From an applications perspective, the creation of an electronically programmed "pro-signal" dramatically expands the toolbox for electronic control of biological responses in microbes, including in complex environments, cell-based materials, and biomanufacturing.

bioengineering↗

bioRxiv2023

Redox-enabled Electronic Interrogation and Feedback Control of Hierarchical and Networked Biological Systems

We enable microelectronic devices to interrogate biologys molecular communication, perform computations, and in real time control biological systems, including at several hierarchical levels: proteins, cells, and cell consortia. A key driver is establishing electronic access to and from biologys native redox networks. First, redox-mediated electro-biofabrication facilitates facile assembly of biological components onto microelectronic systems, then electrode-actuated redox allows digital programming of enzyme activity, and further, redox-mediated electrogenetics facilitates closed-loop electronic control of cellular function. Specifically, we show algorithm-based feedback control of enzyme activity, cellular genetic circuits (via eCRISPR) and cell consortia behavior, all enabled by electronic data transfer. We further demonstrate electronic switching of cell-cell quorum sensing communication from one autoinducer network to another, creating an electronically controlled "bilingual" cell. We suggest these methodologies will not only help us to better understand biological systems, but design and control those currently unimagined.

synthetic biology↗

bioRxiv2023

Mycorrhizal symbiont provides growth benefits in host plants via phosphate and phenylpropanoid metabolism

Using functional interaction assays, Tinctoporellus species isolate AR8 was identified as a plant growth-promoting fungus from Arabidopsis roots. Confocal microscopy revealed interstitial growth and intracellular endophytic colonization within root cortex by AR8 hyphae prior to induction of beneficial effects. AR8 improved plant growth and fitness across a broad range of monocot and dicot host species. AR8 solubilized inorganic phosphate and enabled macronutrient phosphorus assimilation into the host plants, and the resultant growth promotion required an intact phosphate starvation response therein. Metabolomics analysis identified a highly specific subset of primary and secondary metabolites such as sugars, organic acids, sugar alcohols, amino acids, and phenylpropanoids, which were found to be essential for the plant growth-promoting activities of AR8. trans-Cinnamic acid was identified as a novel AR8-induced plant growth promoting metabolite.

plant biology↗

bioRxiv2023

PGSbuilder: An end-to-end platform for human genome association analysis and polygenic risk score predictions

Understanding the genetic basis of human complex diseases is increasingly important in the development of precision medicine. Over the last decade, genome-wide association studies (GWAS) have become a key technique for detecting associations between common diseases and single nucleotide polymorphisms (SNPs) present in a cohort of individuals. Alternatively, the polygenic risk score (PRS), which often applies results from GWAS summary statistics, is calculated for the estimation of genetic propensity to a trait at the individual level. Despite many GWAS and PRS tools being available to analyze a large volume of genotype data, most clinicians and medical researchers are often not familiar with the bioinformatics tools and lack access to a high-performance computing cluster resource. To fill this gap, we provide a publicly available web server, PGSbuilder, for the GWAS and PRS analysis of human genomes with variant annotations. The user-friendly and intuitive PGSbuilder web server is developed to facilitate the discovery of the genetic variants associated with complex traits and diseases for medical professionals with limited computational skills. For GWAS analysis, PGSbuilder provides the most renowned analysis tool PLINK 2.0 package. For PRS, PGSbuilder provides six different PRS methods including Clumping and Thresholding, Lassosum, LDPred2, GenEpi, PRS-CS, and PRSice2. Furthermore, PGSbuilder provides an intuitive user interface to examine the annotated functional effects of variants from known biomedical databases and relevant literature using advanced natural language processing approaches. In conclusion, PGSbuilder offers a reliable platform to aid researchers in advancing the public perception of genomic risk and precision medicine for human disease genetics. PGSbuilder is freely accessible at http://pgsb.tw23.org.

bioinformatics↗

bioRxiv2023

Water-soluble 4-(dimethylaminomethyl)heliomycin exerts greater antitumor effects than parental heliomycin by targeting the tNOX-SIRT1 axis and apoptosis in oral cancer cells

The antibiotic heliomycin (resistomycin), which is generated from Streptomyces resistomycificus, has multiple activities, including anticancer effects. Heliomycin was first described in the 1960s, but its clinical applications have been hindered by extremely low solubility. A series of 4-aminomethyl derivatives of heliomycin were synthesized to increase water solubility; studies showed that they had anti-proliferative effects, but the drug targets remained unknown. In this study, we conducted cellular thermal shift assays (CETSA) and molecular docking simulations to identify and validate that heliomycin and its water-soluble derivative, 4-(dimethylaminomethyl)heliomycin (designated compound 4-dmH) engaged and targeted with sirtuin-1 (SIRT1) in p53-functional SAS and p53-mutated HSC-3 oral cancer cells. We further addressed the cellular outcome of SIRT1 inhibition by these compounds and found that, in addition to SIRT1, the water-soluble 4-dmH preferentially targeted a tumor-associated NADH oxidase (tNOX, ENOX2). The direct binding of 4-dmH to tNOX decreased the oxidation of NADH to NAD+ which diminished NAD+-dependent SIRT1 deacetylase activity, ultimately inducing apoptosis and significant cytotoxicity in both cell types, as opposed to the parental heliomycin-induced autophagy. We also observed that tNOX and SIRT1 were both upregulated in tumor tissues of oral cancer patients compared to adjacent normal tissues, suggesting their clinical relevance. Finally, the better therapeutic efficacy of 4-dmH was confirmed in tumor-bearing mice, which showed greater tNOX and SIRT1 downregulation and tumor volume reduction when treated with 4-dmH compared to heliomycin. Taken together, our in vitro and in vivo findings suggest that the multifaceted properties of water-soluble 4-dmH enable it to offer superior antitumor value compared to parental heliomycin, and indicated that it functions through targeting the tNOX-NAD+-SIRT1 axis to induce apoptosis in oral cancer cells.

cell biology↗

bioRxiv2023

The representational dynamics of the animal appearance bias in human visual cortex are indicative of fast feedforward processing

The human visual system has a seemingly unique tendency to interpret zoomorphic objects as animals, not as objects. This animal appearance bias is very strong in the ventral visual pathway as measured through functional magnetic resonance imaging (fMRI), but it is absent in feedforward deep convolutional neural networks. Here we investigate how this bias emerges over time by probing its representational dynamics through multivariate electroencephalography (EEG). The initially activated representations to lookalike zoomorphic objects are very similar to the representations activated by animal pictures and very different from the neural responses to regular objects. Neural responses that reflect the true identity of the zoomorphic objects as inanimate objects are weaker and appear later, as do effects of task context. The strong early emergence of an animal appearance bias strongly supports a feedforward explanation, indicating that lack of recurrence in deep neural networks is not an explanation for their failure to show this bias.

neuroscience↗

bioRxiv2023

The natural tannins oligomeric proanthocyanidins and punicalagin are potent inhibitors of infection by SARS-CoV-2 in vitro

The COVID-19 pandemic continues to infect people worldwide. While the vaccinated population has been increasing, the rising breakthrough infection persists in the vaccinated population. For living with the virus, the dietary guidelines to prevent virus infection are worthy of and timely to develop further. Tannic acid has been demonstrated to be an effective inhibitor of coronavirus and is under clinical trial. Here we found that two other members of the tannins family, oligomeric proanthocyanidins (OPCs) and punicalagin, are also potent inhibitors against SARS-CoV-2 infection with different mechanisms. OPCs and punicalagin showed inhibitory activity against omicron variants of SARS-CoV-2 infection. The water extractant of the grape seed was rich in OPCs and also exhibited the strongest inhibitory activities for viral entry of wild-type and other variants in vitro. Moreover, we evaluated the inhibitory activity of grape seed extractants (GSE) supplementation against SARS-CoV-2 viral entry in vivo and observed that serum samples from the healthy human subjects had suppressive activity against different variants of SARS-CoV-2 vpp infection after taking GSE capsules. Our results suggest that natural tannins acted as potent inhibitors against SARS-CoV-2 infection, and GSE supplementation could serve as healthy food for infection prevention. HighlightsO_LIOPCs and Punicalagin had inhibitory activity against omicron variants of SARS-CoV-2 infection. C_LIO_LIOPCs serve as a dual inhibitor of the viral Mpro and the cellular TMPRSS2 protease. C_LIO_LIPunicalagin possesses the most potent activity to suppress the Mpro and block the interaction of the viral spike protein and human ACE2. C_LIO_LIOPCs-enriched grape seed extractant exhibited inhibitory activities for viral entry of wild-type and other variants of SARS-CoV-2. C_LIO_LIThe daily intake of grape seed extractants may be able to prevent SARS-CoV-2 infection. C_LI

microbiology↗

bioRxiv2022

SARM1 detection in oligodendrocytes but not Schwann cells though sarm1/Sarm1 deletion does not perturb CNS nor PNS myelination in zebrafish and mice.

SARM1 is a central regulator of programmed axon death and is required to initiate axon self-destruction after traumatic and toxic insults to the nervous system. Abnormal activation of this axon degeneration pathway is increasingly recognized as a contributor to human neurological disease and SARM1 knockdown or inhibition has become an attractive therapeutic strategy to preserve axon loss in a variety of disorders of the peripheral and central nervous system. Despite this, it remains unknown whether Sarm1/SARM1 is present in myelinating glia and whether it plays a role in myelination in the PNS or CNS. It is important to answer these questions to understand whether future therapies inhibiting SARM1 function may have unintended deleterious impacts on myelination. Here we show that Sarm1 mRNA is present in oligodendrocytes in zebrafish but only detectable at low levels in Schwann cells in both zebrafish and mice. We find SARM1 protein is readily detectable in murine oligodendrocytes in vitro and in vivo and activation of endogenous SARM1 in oligodendrocytes induces cell death. In contrast, SARM1 protein is not detectable in Schwann cells and satellite glia in the adult murine nervous system. Cultured Schwann cells contain negligible functional SARM1 and are insensitive to specific SARM1 activators. Using zebrafish and mouse Sarm1 mutants, we show that SARM1 is not required for initiation of myelination nor myelin sheath maintenance by oligodendrocytes and Schwann cells. Thus, strategies to inhibit SARM1 function in the nervous system to treat neurological disease are unlikely to perturb myelination in humans. Main PointsO_LISARM1 protein is detectable in oligodendrocytes but not in Schwann cells C_LIO_LIOligodendrocytes but not Schwann cells die in response to endogenous SARM1 activation C_LIO_LICNS nor PNS myelination, in zebrafish and mice, is hindered by loss of sarm1/Sarm1 C_LI

neuroscience↗

bioRxiv2022

Large-scale benchmarking of circRNA detection tools reveals large differences in sensitivity but not in precision

The detection of circular RNA molecules (circRNAs) is typically based on short-read RNA sequencing data processed by computational detection tools. During the last decade, a plethora of such tools have been developed, but a systematic comparison with orthogonal validation is missing. Here, we set up a circRNA detection tool benchmarking study, in which 16 tools were used and detected over 315,000 unique circRNAs in three deeply sequenced human cell types. Next, 1,516 predicted circRNAs were empirically validated using three orthogonal methods. Generally, tool-specific precision values are high and similar (median of 98.8%, 96.3%, and 95.5% for qPCR, RNase R, and amplicon sequencing, respectively) whereas the sensitivity and number of predicted circRNAs (ranging from 1,372 to 58,032) are the most significant tool differentiators. Furthermore, we demonstrate the complementarity of tools through the increase in detection sensitivity by considering the union of highly-precise tool combinations while keeping the number of false discoveries low. Finally, based on the benchmarking results, recommendations are put forward for circRNA detection and validation.

genomics↗

bioRxiv2022

Using large-scale whole-genome sequence data for single-step genomic predictions in maternal and terminal pig lines

BackgroundWhole-genome sequence (WGS) data harbor causative variants that may not be present in the regular SNP chip data. The objective of this study was to investigate the impact of using preselected variants from WGS for single-step genomic predictions in maternal and terminal pig lines with up to 1.8k sequenced and 104k imputed sequenced animals per line. MethodsTwo maternal and four terminal lines were investigated for eight and seven traits, respectively. The number of sequenced animals ranged from 1,365 to 1,491 in maternal lines and 381 to 1,865 in terminal lines. Imputation occurred within each line, and the number of animals imputed to sequence ranged from 66k to 76k in maternal lines and 29k to 104k in terminal lines. Two preselected SNP sets were generated based on genome-wide association study (GWAS). Top40k included the SNP with the lowest p-value in each of 40k genomic windows; ChipPlusSign included significant variants integrated into the regular porcine SNP chip. Single-step genomic predictions with equal or different SNP variances using those SNP sets were compared to the regular porcine SNP chip. ResultsIn maternal lines, ChipPlusSign, and Top40k showed, on average, 0.62%, and 4.9% increased accuracy compared to the regular porcine SNP chip. The greatest changes were for fertility traits with Top40k, where the initial accuracy based on the SNP chip was low. However, for terminal lines, Top40k resulted in a loss of accuracy of 1% on average. Only ChipPlusSign provided a positive, albeit small, gain (0.85%). Assigning different variances for SNP slightly improved accuracies when using variances obtained from BayesR; however, the increase was inconsistent across the lines and traits. ConclusionsThe benefit of using sequence data depends on the line, size of the genotyped population, and how the WGS variants are preselected. When WGS is available on hundreds of thousands of animals, the advantage of sequence data is present but limited in maternal and terminal pig lines.

genomics↗

bioRxiv2022

Cerebellar granule neurons induce Cyclin D1 in an early stage of Huntington's disease

Although Huntingtons disease (HD) is predominantly defined by selective vulnerability of striatal projection neurons, there is increasing evidence that cerebellar degeneration modulates clinical symptoms. However, little is known about cell type-specific responses of cerebellar neurons in HD. To dissect early disease mechanisms in the cerebellum and cerebrum, we analyzed translatomes of neuronal cell types from both regions in a new HD mouse model. For this, HdhQ200 knock-in mice were backcrossed with the calm, 129S4 strain, to constrain experimental noise caused by variable hyperactivity of mice in a C57BL/6 background. Behavioral and neuropathological characterization showed that these S4-HdhQ200 mice had very mild behavioral abnormalities starting around 12 months of age that remained mild up to 18 months. By 9 months, we observed abundant Huntingtin-positive neuronal intranuclear inclusions (NIIs) in the striatum and cerebellum. The translatome analysis of GABAergic cells of the cerebrum further confirmed changes typical of HD-induced striatal pathology. Surprisingly, we observed the strongest response with 626 differentially expressed genes in glutamatergic neurons of the cerebellum, a population consisting predominantly of granule cells, a cell type commonly considered disease-resistant. Our findings suggest vesicular fusion and exocytosis, as well as differentiation-related pathways are affected. Furthermore, increased expression of cyclin D1 (Ccnd1) in the granular layer and upregulated expression of polycomb group complex protein genes and cell cycle regulators Cbx2, Cbx4 and Cbx8 point to a putative role of aberrant cell cycle regulation in cerebellar granule cells in early disease.

bioinformatics↗

bioRxiv2022

Assessing the impacts of various factors related to identification, conservation, biogenesis, and function on circular RNA reliability

Circular RNAs (circRNAs) are non-polyadenylated RNAs with a continuous loop structure characterized by a non-co-linear back-splice junction (BSJ). While dozens of computational tools have been developed and identified millions of circRNA candidates in diverse species, it remains a major challenge for determining circRNA reliability due to various types of false positives. Here, we systematically assess the impacts of numerous factors related to identification, conservation, biogenesis, and function on circRNA reliability by comparisons of circRNA expression from mock (total RNAs) and the corresponding co-linear/polyadenylated RNA-depleted datasets based on three different RNA treatment approaches. Eight important indicators of circRNA reliability are determined. The relative contribution to variability explained analyses further reveal that the relative importance of these factors in affecting circRNA reliability is conservation level of circRNA > full-length circular sequences > supporting BSJ read count > both BSJ donor and acceptor splice sites at the same co-linear transcript isoforms > both BSJ donor and acceptor splice sites at the annotated exon boundaries > BSJs detected by multiple tools > supporting functional features > both BSJ donor and acceptor splice sites undergoing alternative splicing. By extracting RT-independent circRNAs, circRNAs passing multiple experimental validations, and database-specific circRNAs, we showed the additive effects of these important factors in determining circRNA reliability. This study thus provides a useful guideline and an important resource for selecting high-confidence circRNAs for further investigations.

bioinformatics↗

bioRxiv2022

Changes in calpain-2 expression during glioblastoma progression predisposes tumor cells to temozolomide resistance by minimizing DNA damage and p53-dependent apoptosis

BackgroundGlioblastoma multiforme (GBM) is characterized by an unfavorable prognosis for patients affected. During standard-of-care chemotherapy using temozolomide (TMZ), tumors acquire resistance thereby causing tumor recurrence. Thus, deciphering essential molecular pathways causing TMZ resistance are of high therapeutic relevance. MethodsMass spectrometry based proteomics were used to study the GBM proteome. Immunohistochemistry staining of human GBM tissue for either calpain-1 or -2 was performed to locate expression of proteases. In vitro cell based assays were used to measure cell viability and survival of primary patient-derived GBM cells and established GBM cell lines after TMZ +/- calpain inhibitor administration. shRNA expression knockdowns of either calpain-1 or calpain-2 were generated to study TMZ sensitivity of the specific subunits. The Comet assay and {gamma}H2AX signal measurements were performed in order to assess the DNA damage amount and recognition. Finally, quantitative real-time PCR of target proteins was applied to differentiate between transcriptional and post-translational regulation. ResultsCalcium-dependent calpain proteases, in particular calpain-2, are more abundant in glioblastoma compared to normal brain and increased in patient-matched initial and recurrent glioblastomas. On the cellular level, pharmacological calpain inhibition increased the sensitivities of primary glioblastoma cells towards TMZ. A genetic knockdown of calpain-2 in U251 cells led to increased caspase-3 cleavage and sensitivity to neocarzinostatin, which rapidly induces DNA strand breakage. We hypothesize that calpain-2 causes desensitization of tumor cells against TMZ by preventing strong DNA damage and subsequent apoptosis via post-translational TP53 inhibition. Indeed, proteomic comparison of U251 control vs. U251 calpain-2 knockdown cells highlights perturbed levels of numerous proteins involved in DNA damage response and downstream pathways affecting TP53 and NF-{kappa}B signaling. TP53 showed increased protein abundance, but no transcriptional regulation. ConclusionTMZ-induced cell death in the presence of calpain-2 expression appears to favor DNA repair and promote cell survival. We conclude from our experiments that calpain-2 expression represents a proteomic mode that is associated with higher resistance via "priming" GBM cells to TMZ chemotherapy. Thus, calpain-2 could serve as a prognostic factor for GBM outcome.

cancer biology↗

bioRxiv2022

An efficient and robust tool for colocalisation: Pair-wise Conditional and Colocalisation (PWCoCo)

Genetic colocalisation is an important tool to test for shared genetic aetiology and is commonly used to strengthen causal inference in genetic studies of molecular traits and drug targets. However, the single causal variant assumption of the original colocalization method is a considerable limitation in genomic regions with multiple causal effects. We integrated conditional analyses (GCTA-COJO) and colocalisation analyses (coloc), into a novel analysis tool called Pair-Wise Conditional Colocalization (PWCoCo). PWCoCo performs conditional analyses to identify independent signals for the two tested traits in a genomic region and then conducts colocalisation of each pair of conditionally independent signals for the two traits using summary-level data. This allows for the stringent single-variant assumption to hold for each pair of colocalisation analysis. We found that the computational efficiency of PWCoCo is on average better than colocalisation with Sum of Single Effects Regression using Summary Stats (SuSiE-RSS), with greater gains in efficiency for high-throughput analysis. In a case study using GWAS data for multiple sclerosis and brain cortex-derived eQTLs (MetaBrain), we recapitulated all previously identified genes, which showcased the robustness of the method. We further found colocalisation evidence for secondary signals in nine additional loci, which was not identifiable in conventional GWAS and/or colocalisation. PWCoCo offers key improvements over existing methods, including: (1) robust colocalisation when the single variant assumption is violated; (2) independent colocalisation of secondary signals, which enables identification of novel disease-causing variants; (3) an easy-to-use and computationally efficient tool to test for colocalisation of high-dimensional omics data.

bioinformatics↗

bioRxiv2022

Superior colliculus visual neural sensitivity at the lower limit of natural self-induced image displacements

Visual pattern analysis relies on computations from neurons possessing spatially confined receptive fields. Often, such receptive fields are orders of magnitude larger than the visual pattern components being processed, as well as these components minute displacements on the retina, whether due to small object or self motions. Yet, perception effortlessly handles such visual conditions. Here, we show that in the primate superior colliculus, a brain structure long associated with oculomotor control, neurons with relatively large receptive fields are still sensitive to visual pattern displacements as small as 1 min arc. We used real-time gaze-contingent retinal image stabilization to control the instantaneous spatio-temporal luminance modulation of detailed patterns experienced by neurons, probing sensitivity to the lower limit of natural self-induced image displacements. Despite a large difference between pattern displacement amplitudes and receptive field sizes, collicular neurons were strongly sensitive to the visual pattern consequences of the smallest possible image-shifting eye movements.

neuroscience↗