Biology subjects

Zhang, W.

Publications and source records attributed to Zhang, W..

At least 703 records · Page 39Linked to original sources

bioRxiv2022

AI inspired discovery of new biomarkers for clinical prognosis of liver cancer

Tissue biomarkers are crucial for cancer diagnosis, prognosis assessment, and treatment planning. However, few of current biomarkers used in clinics are robust enough to show a true analytical and clinical value. Thus the search for additional tissue biomarkers, including the strategies to identify them, is imperative. Recently, the capabilities of deep learning (DL)-based computational pathology in cancer diagnosis and prognosis have been explored, but the limited interpretability and generalizability make the results difficult to be accepted in clinical practice. Here we present an interpretable human-centric DL-guided framework--PathFinder (Pathological-biomarker-finder)-- that can inspire pathologists to discover new tissue biomarkers from well-performing DL models, which bridges the gap between DL and clinical prognosis. By combining sparse multi-class tissue spatial distribution information of whole slide images (WSIs) with attribution methods, PathFinder can achieve localization, characterization, and verification of potential biomarkers, while guaranteeing state-of-the-art prognostic performance. With the inspiration of PathFinder, we discovered that tumor necrosis in liver cancer, a long-neglected factor, has a strong relationship with patient prognosis. Thus we proposed two clinically independent indicators, including necrosis area fraction and tumor necrosis distribution, for practical prognosis, and verified their potentials in clinical prognosis according to Reporting Recommendations for Tumor Marker Prognostic Studies (REMARK)-derived criteria. Our work demonstrates a successful example of introducing artificial intelligence (AI) into clinical practice in a knowledge discovery way, which can be adopted in identifying biomarkers in various cancer types and modalities.

cancer biology↗

bioRxiv2022

BA.2.12.1, BA.4 and BA.5 escape antibodies elicited by Omicron infection

SARS-CoV-2 Omicron sublineages BA.2.12.1, BA.4 and BA.5 exhibit higher transmissibility over BA.21. The new variants receptor binding and immune evasion capability require immediate investigation. Here, coupled with Spike structural comparisons, we show that BA.2.12.1 and BA.4/BA.5 exhibit comparable ACE2-binding affinities to BA.2. Importantly, BA.2.12.1 and BA.4/BA.5 display stronger neutralization evasion than BA.2 against the plasma from 3-dose vaccination and, most strikingly, from post-vaccination BA.1 infections. To delineate the underlying antibody evasion mechanism, we determined the escaping mutation profiles2, epitope distribution3 and Omicron neutralization efficacy of 1640 RBD-directed neutralizing antibodies (NAbs), including 614 isolated from BA.1 convalescents. Interestingly, post-vaccination BA.1 infection mainly recalls wildtype-induced humoral memory. The resulting elicited antibodies could neutralize both wildtype and BA.1 and are enriched on non-ACE2-competing epitopes. However, most of these cross-reactive NAbs are heavily escaped by L452Q, L452R and F486V. BA.1 infection can also induce new clones of BA.1-specific antibodies that potently neutralize BA.1; nevertheless, these NAbs are largely escaped by BA.2/BA.4/BA.5 due to D405N and F486V, and react weakly to pre-Omicron variants, exhibiting poor neutralization breadths. As for therapeutic NAbs, Bebtelovimab4 and Cilgavimab5 can effectively neutralize BA.2.12.1 and BA.4/BA.5, while the S371F, D405N and R408S mutations would undermine most broad sarbecovirus NAbs. Together, our results indicate that Omicron may evolve mutations to evade the humoral immunity elicited by BA.1 infection, suggesting that BA.1-derived vaccine boosters may not achieve broad-spectrum protection against new Omicron variants.

immunology↗

bioRxiv2022

ILC3s select for RORγt+ Tregs and establish tolerance to intestinal microbiota

Microbial colonization of the mammalian intestine elicits inflammatory or tolerogenic T cell responses, but the mechanisms controlling these distinct outcomes remain poorly understood and accumulating evidence indicates that aberrant immunity to intestinal microbiota is causally associated with infectious, inflammatory, and malignant diseases1-8. Here, we define a critical pathway controlling the fate of inflammatory versus tolerogenic T cells that are specific for the microbiota and express the transcription factor ROR{gamma}t. We profiled all ROR{gamma}t+ immune cells at single cell resolution from the intestine-draining lymph nodes of mice and reveal a dominant presence of Tregs and lymphoid tissue-induced (LTi)-like group 3 innate lymphoid cells (ILC3s), which co-localize at interfollicular regions. These ILC3s have interconverting potential with ROR{gamma}t+ extrathymic Aire-expressing cells, abundantly express major histocompatibility complex class II, and are necessary and sufficient to promote microbiota-specific ROR{gamma}t+ Tregs and prevent their expansion as inflammatory T helper (Th)17 cells. This occurs through ILC3-mediated antigen-presentation, interleukin-2 gradients, and v integrin. Finally, single-cell analyses demonstrate that ILC3 and ROR{gamma}t+ Treg interactions are impaired in inflammatory bowel disease. Our results define a novel paradigm whereby ILC3s positively select for antigen specific ROR{gamma}t+ Tregs, and against Th17 cells, to establish immune tolerance to the microbiota and intestinal health.

immunology↗

bioRxiv2022

Debugging and consolidating multiple synthetic chromosomes reveals combinatorial genetic interactions

The Sc2.0 project is building a eukaryotic synthetic genome from scratch, incorporating thousands of designer features. A major milestone has been achieved with the assembly of all individual Sc2.0 chromosomes. Here, we describe the consolidation of multiple synthetic chromosomes using endoreduplication intercross to generate a strain with 6.5 synthetic chromosomes. Genome-wide chromosome conformation capture and long-read direct RNA sequencing were performed on this strain to evaluate the effects of designer modifications, such as loxPsym site insertion, tRNA relocation, and intron deletion, on 3D chromosome organization and transcript isoform profiles. To precisely map "bugs", we developed a method, CRISPR Directed Biallelic URA3-assisted Genome Scan, or "CRISPR D-BUGS", exploiting directed mitotic recombination in heterozygous diploids. Using this method, we first fine-mapped a synII defect resulting from two loxPsym sites in the 3 UTR of SHM1. This approach was also used to map a combinatorial bug associated with synIII and synX, revealing a highly unexpected genetic interaction that links transcriptional regulation, inositol metabolism and tRNASerCGA abundance. "Starvation" for tRNASerCGA leads to insufficient levels of the key positive inositol biosynthesis regulator, Swi3, which contains tandem UCG codons. Finally, to expedite consolidation, we employed a new method, chromosome swapping, to incorporate the largest chromosome (synIV), thereby consolidating more than half of the Sc2.0 genome in a single strain.

genomics↗

bioRxiv2022

Manipulating the 3D organization of the largest synthetic yeast chromosome

Whether synthetic genomes can power life has attracted broad interest in the synthetic biology field, especially when the synthetic genomes are extensively modified with thousands of designer features. Here we report de novo synthesis of the largest eukaryotic chromosome thus far, synIV, a 1,454,621-bp Saccharomyces cerevisiae chromosome resulting from extensive genome streamlining and modification. During the construction of synIV, we developed megachunk assembly combined with a hierarchical integration strategy, which significantly increased the accuracy and flexibility of synthetic chromosome construction and facilitated chromosome debugging. In addition to the drastic sequence changes made to synIV by rewriting it, we further manipulated the three-dimensional structure of synIV in the yeast nucleus to explore spatial gene regulation within the nuclear space. Surprisingly, we found few gene expression changes, suggesting that positioning inside the yeast nucleoplasm plays a minor role in gene regulation. Lastly, we tethered synIV to the inner nuclear membrane via its hundreds of loxPsym sites and observed transcriptional repression of the entire chromosome, demonstrating chromosome-wide transcription manipulation without changing the DNA sequences. Our manipulation of the spatial structure of the largest synthetic yeast chromosome shed light on higher-order architectural design of the synthetic genomes. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/487066v2_ufig1.gif" ALT="Figure 1"> View larger version (64K): org.highwire.dtl.DTLVardef@18bf586org.highwire.dtl.DTLVardef@1a471d5org.highwire.dtl.DTLVardef@12d7690org.highwire.dtl.DTLVardef@1c32510_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIDe novo synthesis of the largest eukaryotic chromosome, synIV C_LIO_LISynIV shows similar 3D structure to wild-type IV, despite thousands of changes made to it C_LIO_LI"Inside-out" repositioning of synIV in nucleus shows minor transcriptional changes C_LIO_LIMultipoint tethering synIV to inner nuclear membrane represses transcription of whole chromosome C_LI

synthetic biology↗

bioRxiv2022

Antibody Resistance of SARS-CoV-2 Omicron BA.1, BA.1.1, BA.2 and BA.3 Sub-lineages

The SARS-CoV-2 Omicron variant has been partitioned into four sub-lineages designated BA.1, BA.1.1, BA.2 and BA.3, with BA.2 becoming dominant worldwide recently by outcompeting BA.1 and BA.1.1. We and others have reported the striking antibody evasion of BA.1 and BA.2, but side-by-side comparison of susceptibility of all the major Omicron sub-lineages to vaccine-elicited or monoclonal antibody (mAb)-mediated neutralization are urgently needed. Using VSV-based pseudovirus, we found that sera from individuals vaccinated by two doses of inactivated whole-virion vaccines (BBIBP-CorV) showed very weak to no neutralization activity, while a homologous inactivated vaccine booster or a heterologous booster with protein subunit vaccine (ZF2001) markedly improved the neutralization titers against all Omicron variants. The comparison between sub-lineages indicated that BA.1.1, BA.2 and BA.3 had comparable or even greater antibody resistance than BA.1. We further evaluated the neutralization profile of a panel of 20 mAbs, including 10 already authorized or approved, against these Omicron sub-lineages as well as viruses with different Omicron spike single or combined mutations. Most mAbs lost their neutralizing activity completely or substantially, while some demonstrated distinct neutralization patterns among Omicron sub-lineages, reflecting their antigenic difference. Taken together, our results suggest all four Omicron sub-lineages threaten the efficacies of current vaccines and antibody therapeutics, highlighting the importance of vaccine boosters to combat the emerging SARS-CoV-2 variants.

microbiology↗

bioRxiv2022

A Deep Learning Method for MiRNA/IsomiR Target Detection

MotivationAccurate identification of microRNA (miRNA) targets at base-pair resolution has been an open problem for over a decade. The recent discovery of miRNA isoforms (isomiRs) adds more complexity to this problem. Despite the existence of many methods, none considers isomiRs, and their performance is still suboptimal. We hypothesize that by taking the isomiR-mRNA interaction into account and applying a deep learning model to study miRNA-mRNA interaction features, we may improve the accuracy of miRNA target predictions. ResultsWe developed a deep learning tool called DMISO to capture the intricate features of miRNA/isomiR-mRNA interactions. Based on 10-fold cross-validation, DMISO showed high precision (95%) and recall (90%). Evaluated on three independent datasets, DMISO had superior performance to five tools, including three popular conventional tools and two recently developed deep learning-based tools. By applying two popular feature interpretation strategies, we demonstrated the importance of the miRNA regions other than their seeds and the potential contribution of the RNA-binding motifs within miRNAs/isomiRs and mRNAs to the miRNA/isomiR-mRNA interactions. AvailabilityThe source code and tool are available at http://hulab.ucf.edu/research/projects/DMISO. Contacthaihu@cs.ucf.edu, xiaoman@mail.ucf.edu Supplementary informationSupplementary data are available online.

bioinformatics↗

bioRxiv2022

The catalytic domain of cellulose synthase (CESA) is involved in vesicle trafficking and protein dynamics

Cellulose, as the main component of the plant cell wall, is synthesized by a multimeric protein complex named the cellulose synthase (CESA) complex or CSC. In plant cells, CSCs are transported through the endomembrane system to the PM, but how catalytic activity or conserved motifs around the catalytic core domain influence vesicle trafficking or protein dynamics is not well understood. Here, we used a functional YFP-tagged AtCESA6 and site- directed mutagenesis to create 18 single amino acid replacement mutants in key motifs of the catalytic domain including DDG, DXD, TED and QXXRW, to comprehensively analyze how catalytic activity affects plant growth, cellulose biosynthesis, complex formation, as well as CSC dynamics and trafficking. Plant growth and cellulose content were reduced by nearly all mutations. Moreover, mutations in most conserved motifs reduced the speed of CSC movement in the PM as well as delivery of CSCs to the PM. Interestingly, the abundance of YFP-CESA6 in the Golgi apparatus was increased or reduced by mutations in DDG and QXXRW motifs, respectively. Post-Golgi trafficking of CSCs was also differentially perturbed by these mutations and, based on these phenotypes, the 18 mutations could be divided into two major groups. Group I comprises mutations causing significantly increased fluorescence intensity of YFP-CESA6 in Golgi with either an increase or no change in the abundance of cortical small CESA-containing compartments (SmaCCs). In contrast, Group II represents mutations with significantly decreased fluorescence intensity of YFP-CESA6 in Golgi and/or reduced SmaCC density. In addition, two Group II mutations in the QXXRW motif reduced CSC assembly in the Golgi. We propose that Group I mutations cause CSC trafficking defects whereas Group II mutations, especially in the QXXRW motif, affect normal CSC rosette formation in the ER or Golgi and hence interfere with subsequent CSC trafficking. Collectively, our results demonstrate that the catalytic domain of CESA6 is essential not only for cellulose biosynthesis, but also CESA complex formation, protein folding and dynamics, vesicle trafficking, or all of the above. One sentence summaryA comprehensive mutational analysis of the catalytic domain of Arabidopsis CESA6 reveals distinct roles for conserved motifs in CSC vesicle trafficking, protein complex formation, or protein dynamics

plant biology↗

bioRxiv2022

Convergent impact of schizophrenia risk genes

Genetic studies of schizophrenia reveal a complex polygenic risk architecture comprised of hundreds of risk variants; most are common in the population at-large, non-coding, and act by genetically regulating the expression of one or more gene targets ("eGenes"). It remains unclear how genetic variants predicted to confer individually small effects combine to yield substantial clinical impacts in aggregate. Here, we demonstrate that eGenes have shared downstream transcriptomic effects ("convergence") that may underlie unexpected interactions ("non-additive effects") observed when eGenes are manipulated in combination. We apply a pooled CRISPR approach to perturb schizophrenia eGenes in human induced pluripotent stem cell-derived glutamatergic neurons. The strength and specificity of convergence increased between functionally similar eGenes. Predicting that convergence might impact additive relationships between risk loci when inherited together, we use an arrayed approach to explore bidirectional combinatorial perturbations of a partially overlapping set of fifteen schizophrenia eGenes. When specifically considering groups of synaptic or epigenetic eGenes, combinatorial eGene perturbations yield changes that are smaller than predicted by summing individual eGene effects ("sub-additive effects"). Moreover, convergent and non-additive downstream transcriptomic effects overlap, suggesting that functional redundancy of eGenes may be a major mechanism underlying non-additivity. Combinatorial perturbations result in outcomes that are not yet well-predicted by single eGene perturbations alone, indicating that the effects of polygenic risk cannot necessarily be extrapolated from experiments testing one risk gene at a time.

neuroscience↗

bioRxiv2022

Genome-wide signatures of geographic expansion and breeding process in soybean

The clarification of genomic signatures left during evolutionary histories of crops is crucial for breeding varieties adapting to changing climate. Soybean, a leguminous crop, provides both plant oil and protein. Here, we analyzed genome sequences of 2,214 soybeans and proposed its evolutionary route, which includes four geographic paths, expansion of annual wild soybean (Glycine soja Sieb. & Zucc.) from Southern China, domestication in Central China, expansion of landrace (G. max (L.) Merr.), and local breeding. We observed that local adaptation of the wild and cultivated soybeans was largely independent, and that genetic introgression was mostly derived from sympatric rather than allopatric wild populations during the range expansion of soybean landraces. Range expansion and breeding processes were accompanied with positive selection of flowering-time genes including GmSPA3c as validated by knock-out mutants. Our study shed lights on the evolutionary history of soybean and provides valuable genetic resources for future breeding. TeaserThe expansion and selection history of soybean

genomics↗

bioRxiv2022

Drivers of nematode diversity in forest soils across climatic zones

Nematodes are the most abundant multi-cellular animals in soil, influencing key processes and functions in terrestrial ecosystems. Yet, little is known about the drivers of nematode abundance and diversity in forest soils across climatic zones. This is despite forests cover approximately 30% of the earths land surface, provide many crucial ecosystem services but strongly vary in hydrothermal conditions and associated ecosystem properties across climatic zones. Here, we collected nematode samples from 13 forests across a latitudinal gradient. We divided this gradient in temperate, warm-temperate, and tropical climatic zones. Using boosted regression trees, we showed that across the gradient, nematode abundance and diversity were mainly influenced by soil organic carbon. However, within climatic zones, other factors were more important in driving nematode alpha-diversity, nematode biomass and the abundance of different trophic groups: mean annual temperature and total soil phosphorus in temperate zones, soil pH in warm-temperate zones, and mean annual precipitation in tropical zones. Additionally, nematode beta-diversity was higher in temperate than in warm-temperate and tropical zones, and we did not find significant differences among climatic zones in nematode gamma diversity. Together, our findings indicate a latitudinal shift in the main climatic variables controlling soil nematode communities and demonstrate that the drivers of soil nematode diversity in forested ecosystems are affected by the spatial scale and climatic conditions considered. This implies that high resolution studies are needed to accurately predict how soil functions respond if climate conditions move beyond the coping range of soil organisms. Our results also emphasize the importance of studying the area-diversity relationship of soil organisms under different climatic conditions.

ecology↗

bioRxiv2022

Integrative DNA methylation analysis of pediatric brain tumors reveals tumor type-specific developmental trajectories and epigenetic signatures of malignancy

Atypical teratoid/rhabdoid tumors (AT/RTs) are pediatric brain tumors known for their aggressiveness, exceptionally low mutation rate, and aberrant but still unresolved epigenetic regulation. To evaluate methylation associated regulation in AT/RTs, we compared them to medulloblastomas and choroid plexus tumors by integrating DNA methylation (507 samples), gene expression (120 samples), and public transcription factor (TF) binding data. We showed that elevated DNA methylation masks the binding sites of TFs driving neural development and is associated with reduced transcription for specific neural regulators in AT/RTs. Part of the hypermethylated sites behaved similarly in AT/RTs and pluripotent stem cells, revealing DNA methylation -driven halted cell differentiation. AT/RT-unique DNA hypermethylation was associated with polycomb repressive complex 2 members, like EZH2, and linked to suppressed genes with a role in neural development and tumorigenesis. The obtained results highlight and characterize these DNA methylation programs as drivers of AT/RT malignancy.

cancer biology↗

bioRxiv2022

Lnc956-TRIM28-HSP90B1 complex on replication forks promotes CMG helicase retention to ensure stem cell genomic stability and embryogenesis

Replication stress is a major source of endogenous DNA damage. Despite that numerous proteins have been identified on replication forks to modulate fork or replication machinery activities, it remains unexplored whether non-coding RNAs can localize on stalled forks and play critical regulatory roles. Here we identify an uncharacterized lncRNA NONMMUT028956 (Lnc956 for short) predominantly expressed in mouse embryonic stem cells. Lnc956 is recruited to stalled replication forks to prevent fork collapse and preserve genomic stability, and is essential for mouse embryogenesis. Mechanistically, it drives assembly of the Lnc956-TRIM28-HSP90B1 ribonucleoprotein (RNP) complex on stalled forks in an inter-dependent manner downstream of ATR signaling. This RNP complex physically associates with MCM2-7 hexamer via TRIM28 and directly regulates the CMG helicase retention on chromatin. The regulation of RNP on CMG retention is mediated by HSP90B1s chaperoning function. These findings reveal a novel pathway which actively regulates replisome retention to prevent fork collapse.

cell biology↗

bioRxiv2022

Mice regulate their attentional intensity and arousal to exploit increases in task utility

Changes in autonomic arousal, such as mounting sleep pressure, and changes in motivation, such as fluctuating environmental reward statistics, both profoundly influence behavior. Our experience tells us that we have some capacity to control our arousal when doing so is important, such as staying awake while driving a motor vehicle. However, little is known about how decision computations are jointly influenced by arousal and motivation, including whether animals, such as rodents, can adapt their arousal state to their needs. Here, we developed and show results from an auditory feature-based sustained-attention task with intermittently shifting task utility. We use pupil size to estimate arousal across a wide range of states and apply novel signal detection theoretic and accumulation-to-bound modeling approaches in a large behavioral cohort. We find that both pupil-linked arousal and task utility have major impacts on multiple aspects of performance. Although substantial arousal fluctuations persist across utility conditions, mice partially stabilize their arousal near an intermediate, and optimal, level when task utility is high. Behavioral analyses show that multiple elements of behavior improve during high task utility and that arousal influences some, but not all, of them. Specifically, arousal influences the likelihood and timescale of sensory evidence accumulation, but not the quantity of evidence accumulated per time step while attending. In sum, the results establish specific decision-computational signatures of arousal, motivation, and their interaction, in attention. So doing, we provide an experimental and analysis framework for studying arousal self-regulation in neurotypical brains and diseases such as attention-deficit/hyperactivity disorder.

neuroscience↗

bioRxiv2022

Rational evolution of a recombinant DNA polymerase for efficient incorporation of unnatural nucleotides by dual-site boosting

Machine learning modelling assisting function-oriented enzyme engineering is normally built on predefined protein sequence space. However, efficient defining the determinant amino acid positions upon which the combinatorial mutation library is constructed is still a challenge in protein science. Herein, we present a comprehensive investigation of modifying a recombinant DNA polymerase for efficient incorporating one unnatural nucleotide, including the identification of key sites/regions, machine learning-assisted mutants screening, and the underlying mechanism of kinetics boosting. By using hundreds of training points and only dozens of testing samples, we found that one highly engineered enzymes catalytic efficiency can be further improved by one order of magnitude by specific mutation on two sites, 485I and 451L. Compared to the position 485 which is known to dominate local conformation of B-family DNA polymerases, 451 is a split-new active site discovered by our approach. A novel allosteric regulation mechanism is underlying the apparent synergy of 485I and 451L on the kinetics boosting. As a result, a "half-closed" conformation of the binding pocket and a cooperative binding of both primer and template DNA strands on the protein accelerated the processes of substrates incorporation, molecular recognition, and releasing of incorrect nucleotides. These findings have implications in guiding the function-tuning of DNA polymerases for a broad range of biotechnological applications.

biochemistry↗

bioRxiv2022

Omicron booster in ancestral strain vaccinated mouse augments protective immunities against both the Delta and Omicron variants

A booster vaccination is called for constraining the evolving epidemic of SARS-CoV-2. However, the necessity of a new COVID-19 vaccine is currently unclear. To compare the effect of an Omicron-matched S DNA vaccine and an ancestral S DNA vaccine in boosting cross-reactive immunities, we firstly immunized mice with two-dose of a DNA vaccine encoding the spike protein of the ancestral Wuhan strain. Then the mice were boosted with DNA vaccines encoding spike proteins of either the Wuhan strain or the Omicron variant. Specific antibody and T cell responses were measured at 4 weeks post boost. Our data showed that the Omicron-matched vaccine efficiently boosted RBD binding antibody and neutralizing antibody responses against both the Delta and the Omicron variants. Of note, antibody responses against the Omicron variant elicited by the Omicron-matched vaccine were much stronger than those induced by the ancestral S DNA vaccine. Meanwhile, CD8+ T cell responses against both the ancestral Wuhan strain and the Omicron strain also tended to be higher in mice boosted by the Omicron-matched vaccine than those in mice boosted with the ancestral S DNA vaccine, albeit no significant difference was observed. Our findings suggest that an Omicron-matched vaccine is preferred for boosting cross-reactive immunities.

immunology↗

bioRxiv2022

cLD: Rare-variant disequilibrium between genomic regions identifies novel genomic interactions

Linkage disequilibrium (LD) is a fundamental concept in genetics; critical for studying genetic associations and molecular evolution. However, LD measurements are only reliable for common genetic variants, leaving low-frequency variants unanalyzed. In this work, we introduce cumulative LD (cLD), a stable statistic that captures the rare-variant LD between genetic regions, which reflects more biological interactions between variants, in addition to lack of recombination. We derived the theoretical variance of cLD using delta methods to demonstrate its higher stability than LD for rare variants. This property is also verified by bootstrapped simulations using real data. In application, we find cLD reveals an increased genetic association between genes in 3D chromatin interactions, a phenomenon recently reported negatively by calculating standard LD between common variants. Additionally, we show that cLD is higher between gene pairs reported in interaction databases, identifies unreported protein-protein interactions, and reveals interacting genes distinguishing case/control samples in association studies.

bioinformatics↗

bioRxiv2022

Biochemical analysis challenging Western blot analysis as validation step for antibodies intended for ELISA and immunohistochemistry

The relative contributions of the conformation and primary structure of an epitope to overall antigen-antibody interaction (AAI) at denatured, native or formalin fixed (FF) state were compared using six randomly chosen commercial antibodies using Quantitative Dot Blot (QDB) method. AAIs at native and FF states were found ranged 1.3 [~] 10.2 and 0.5 [~] 45.4 folds, respectively, over those at denatured state in cellular and tissue lysates. Using two antibodies against different epitopes of PYGL protein, we showed that PYGL levels in several types of tissues and cell lines were highly correlated (r=0.99 from Pearson, p<0.0001, n=25) when measured with these two antibodies at native state. Yet, one antibody was found to be nonspecific with one type of these tissues using Western blot analysis. These observations suggested that the conformation of an epitope may serve as dominant contributor of overall AAI at native state in general, regardless of linear or conformational epitopes. In many cases, it would override nonspecific interactions formed at denatured state to challenge Western blot analysis as a validation tool for antibodies intended for immunohistochemistry (IHC) and ELISA.

biochemistry↗