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Biology subjects

Pan, L.

Publications and source records attributed to Pan, L..

At least 55 records · Page 3Linked to original sources

Accurate nucleic acid-binding residue identification based on domain-adaptive protein language model and explainable geometric deep learning

Protein-nucleic acid interactions play a fundamental and critical role in a wide range of life activities. Accurate identification of nucleic acid-binding residues helps to understand the intrinsic mechanisms of the interactions. However, the accuracy and interpretability of existing computational methods for recognizing nucleic acid-binding residues need to be further improved. Here, we propose a novel method called GeSite based the domain adaptive protein language model and explainable E(3)-equivariant graph convolution neural network. Prediction results across multiple benchmark test sets demonstrate that GeSite is superior or comparable to state-of-the-art prediction methods. The performance comparison on low structure similarity and newly released test proteins demonstrates the robustness and generalization of the method. Detailed experimental results suggest that the advanced performance of GeSite lies in the well-designed nucleic acid-binding protein adaptive language model. Meanwhile, interpretability analysis exposes the perception of the prediction model on various remote and close functional domains, which is the source of its discernment. The data and source code of GeSite are freely accessible at https://github.com/pengsl-lab/GeSite.

bioinformatics↗

HCN1 channels in GABAergic amygdalar neurons underpin male-biased aggressive behaviors

Aggression behaviors typically vary between sexes, but the molecular mechanisms driving these disparities in neural coding are unclear. We found that aggression selectively activates GABAergic neurons in the posterior substantia innominata (pSI), an extend amygdala region critical for aggressive behaviors in both sexes of mice, with males exhibiting higher neuronal activity during the attack. Utilizing single-nucleus RNA sequencing, we characterized the diverse molecular landscape of pSI neurons, revealing significant differences in ion channels and hormone regulator genes that may underpin sex-specific aggression. Male GABAergic pSI neurons exhibited remarkable hyperexcitability due to increased Ih currents. Strikingly, modulating HCN1 expression not only adjusted this hyperexcitability but also influenced sexual dimorphism in aggression: silencing HCN1 in the GABAergic pSI neurons reduced male aggression, while its overexpression markedly heightened aggression in females. Furthermore, testosterone was shown to intensify aggression by upregulating HCN1 and remodeling pSI circuits. These findings provide detailed sex-specific molecular mechanisms underlying social behaviors.

neuroscience↗

The follicular lymphoma and chronic lymphocytic leukemia proliferative microenvironment at single-cell resolution

Adaptive immune responses occur lymph nodes (LNs) in a microenvironment established by resident stromal cells. LNs are also a site of proliferation of chronic lymphocytic leukemia (CLL), a B cell cancer that alters LN structure in a stereotypic manner. To deeply characterize reactive and CLL LNs, we developed a single-cell RNA sequencing pipeline. We find that proliferation of CLL cells in proliferation centers (PCs), a CLL-specific niche, begins with transient upregulation of MYC, subsequent downregulation of which may limit CLL growth. PCs contain a distinct fibroblast population expressing CCL19 while CLL cells express the CCL19 receptor CCR7, providing a recruitment mechanism for CLL cells to PCs. Using informatic, spatial, and in situ analyses to identify ligand-receptor pairs involving PC CLL cells and nearby immune and stromal cells, we observe that PCs are enriched for macrophages expressing BAFF, the integrin X{beta}2 heterodimer, and Galectin9, factors implicated in cell growth, adhesion, and immunosuppression. The most common predicted interactions in PCs involve CD74 and ligands such as MIF, and we find that CD74 blockade consistently inhibits CLL cell growth in culture. Our work highlights key features of the CLL proliferative niche and provides a roadmap for identifying vulnerabilities and new therapeutic strategies.

pathology↗

Interpretable improving prediction performance of general protein language model by domain-adaptive pretraining on DNA-binding protein

DNA-protein interactions exert the fundamental structure of many pivotal biological processes, such as DNA replication, transcription, and gene regulation. However, accurate and efficient computational methods for identifying these interactions are still lacking. In this study, we propose a novel method ESM-DBP through refining the DNA-binding protein (DBP) sequence repertory and domain-adaptive pretraining based the protein language model (PLM). Our method considers the lack of exploration of general PLM for DBP domain-specific knowledge, so we screened out 170,264 DBPs from the UniProtKB database to construct the model that more suitable for learning crucial characteristics of DBP. The evaluation of ESM-DBP is systematically performed in four different DBP-related downstream prediction tasks, i.e., DNA-binding protein, DNA-binding residue, transcription factor, and DNA-binding Cys2His2 zinc-finger predictions. Experimental results show that ESM-DBP provides a better feature representation of DBP compared to the original PLM, resulting in improved prediction performance and outperforming other state-of-the-art prediction methods. In addition, ESM-DBP incorporates the integrated gradient algorithm for interpretable analysis, which usually ignored in the previous methods. It reveals that ESM-DBP possesses high sensitivity to the key decisive DNA-binding domains. Moreover, we find that ESM-DBP can still perform well even for those DBPs with only a few similar homologous sequences, and this generalization performs better than the original PLM. The data and standalone program of ESM-DBP are freely accessible at https://github.com/pengsl-lab/ESM-DBP.

bioinformatics↗

A smartphone-based genetically recombinant whole-cell biosensor for highly sensitive monitoring of polychlorinated biphenyls (PCBs)

Polychlorinated biphenyls (PCBs) are highly carcinogenic and persistent pollutants commonly found in ecosystems. Their complex congeners pose a huge challenge to instrumental analysis and ELISA methods, which prefer single and known targets. To overcome this limitation, here we developed an Escherichia coli whole-cell biosensor (WCB) for simultaneously detecting multiple PCB congeners. In this sensor, PCBs were firstly converted into hydroxylated PCBs (OH-PCBs) by bphAB degradation circuits, which then serve as high-affinity targets of transcriptional factor HbpRCBP6-based sensing pathways for sensitive response through extensive chassis screening. The resulting biosensor BL21(DE3)/HbpRCBP6-bphAB shows the lowest detection limits for 2-CBP (2-chlorobiphenyl) to date and can recognize various PCB homologues, including 3-CBP, 4-CBP, 2,3-diCBP and 2,2-diCBP, with detection limits of 0.06-1 M. Further investigation of the docking structure and binding energy reveal that HbpRCBP6 has a stronger affinity for OH-PCBs than for PCBs, indicating that the conversion of PCB by BphAB enzymes is a key step to improve the sensitivity of WCB. Subsequently, we developed an immobilized hydrogel WCB and a smartphone-based detection procedure to facilitate real-time and user-friendly PCB detection. This study will not only advance the biomonitoring of PCB contaminants but also provide an innovative strategy for developing metabolic pathway-sensing proteins combined biosensor. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/601110v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@10772cdorg.highwire.dtl.DTLVardef@22699org.highwire.dtl.DTLVardef@1343c27org.highwire.dtl.DTLVardef@595859_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

A genome resource for the marine annelid Platynereis dumerilii

The marine annelid Platynereis dumerilii is a model organism used in many research areas including evolution and development, neurobiology, ecology and regeneration. Here we present the genomes of P. dumerilii (laboratory culture reference and a single individual assembly) and of the closely related P. massiliensis and P. megalops (single individual assembly) to facilitate comparative genomic approaches and help explore Platynereis biology. We used long-read sequencing technology and chromosomal-conformation capture along with extensive transcriptomic resources to obtain and annotate a draft genome assembly of [~]1.47 Gbp for P. dumerilii, of which more than half represent repeat elements. We predict around 29,000 protein-coding genes, with relatively large intron sizes, over 38,000 non-coding genes, and 105 miRNA loci. We further explore the high genetic variation ([~]3% heterozygosity) within the Platynereis species complex. Gene ontology reveals the most variable loci to be associated with pigmentation, development and immunity. The current work sets the stage for further development of Platynereis genomic resources.

genomics↗

Single-cell morphology encodes functional subtypes of senescence in aging human dermal fibroblasts

Cellular senescence is an established driver of aging, exhibiting context-dependent phenotypes across multiple biological length-scales. Despite its mechanistic importance, profiling senescence within cell populations is challenging. This is in part due to the limitations of current biomarkers to robustly identify senescent cells across biological settings, and the heterogeneous, non-binary phenotypes exhibited by senescent cells. Using a panel of primary dermal fibroblasts, we combined live single-cell imaging, machine learning, multiple senescence induction conditions, and multiple protein-based senescence biomarkers to show the emergence of functional subtypes of senescence. Leveraging single-cell morphologies, we defined eleven distinct morphology clusters, with the abundance of cells in each cluster being dependent on the mode of senescence induction, the time post-induction, and the age of the donor. Of these eleven clusters, we identified three bona-fide senescence subtypes (C7, C10, C11), with C10 showing the strongest age-dependence across a cohort of fifty aging individuals. To determine the functional significance of these senescence subtypes, we profiled their responses to senotherapies, specifically focusing on Dasatinib + Quercetin (D+Q). Results indicated subtype-dependent responses, with senescent cells in C7 being most responsive to D+Q. Altogether, we provide a robust single-cell framework to identify and classify functional senescence subtypes with applications for next-generation senotherapy screens, and the potential to explain heterogeneous senescence phenotypes across biological settings based on the presence and abundance of distinct senescence subtypes.

bioengineering↗

Native β-barrel substrates pass through two shared intermediates during folding on the BAM complex

The assembly of {beta}-barrel proteins into membranes is mediated by the evolutionarily conserved BAM complex. In Escherichia coli, BAM folds numerous substrates which vary considerably in size and shape. How BAM is able to efficiently fold such a diverse array of {beta}-barrel substrates is not clear. Here, we develop a disulfide crosslinking method to trap native substrates in vivo as they fold on BAM. By placing a cysteine within the luminal wall of the BamA barrel as well as in the substrate {beta}-strands, we can compare the residence time of each substrate strand within the BamA lumen. We validated this method using two defective, slow-folding substrates. We used this method to characterize stable intermediates which occur during folding of two structurally different native substrates. Strikingly, these intermediates occur during identical stages of folding for both substrates: soon after folding has begun, and just before folding is completed. We suggest that these intermediates arise due to barriers to folding that are common between {beta}-barrel substrates, and that the BAM catalyst is able to fold so many different substrates because it addresses these common challenges. Significance StatementThe outer membrane of Gram-negative bacteria is a barrier which protects these organisms from many antimicrobial agents. Here, we study the machine responsible for folding and inserting integral {beta}-barrel proteins into the membrane: BAM. Outer membrane integrity and cell viability is dependent on the proper function of BAM. Here we show that stable intermediates exist on the folding pathway of native substrates. We also show that mutant substrates that increase the stability of these native intermediates can stall during folding. This creates permeability defects that can be exploited by antibiotics that normally do not cross the outer membrane. These observations could enable the design of strategies to combat Gram-negative pathogens.

biochemistry↗

A rapid and efficient in vivo inoculation method for introducing tree stem canker pathogens onto leaves, suitable for large-scale assessment of resistance in poplar breeding progeny

Hybrid breeding, a direct and efficient strategy for disease control and management in tree species, is currently limited by the selection method of resist clones: the "in vitro stem segment inoculation method." This method, constrained by the availability of inoculating materials, cannot rapidly, efficiently, and cost-effectively screen the resistance of all hybrid clones. To overcome these limitations, we introduce a novel pathogen inoculation method for the resistance assessment of hybrid clones in the poplar-Valsa sordida pathosystem. This method involves inoculating the stem canker pathogen on the host leaf, a unique and promising approach we have successfully validated. Results showed that stem canker pathogen V. sordida induced the extended necrotic lesion and even induced the formation of pycnidium structure and conidia on the leaf surface five days after mycelium inoculation; 1) the upper 5-7th leaves exhibited higher resistance than the middle 18-20th leaves; 2) the shading conditions induced more severe symptoms on the leaves than lighting conditions; 3) the juvenile mycelium inoculums (4-day-cultured) were more susceptible to poplar leaves than the old ones (7-day-cultured). Our results demonstrate the robustness of the "in vivo leaf inoculation method" in revealing the resistance differentiation in poplar hybrid clones. According to the leaf necrotic area disease index, we divided these poplar clones into seven different resistance groups. The resistance assessed by leaf assessment was validated in 15 selected poplar clones using the "in vitro stem segment inoculation method." Results showed that the effectiveness of these two methods was consistent. Moreover, the leaf inoculation method can be used to detect the pathogenicity diversity of the pathogen population of tree species. Compared to the conventional "in vitro stem segment inoculation method," the leaf method has the advantages of abundant inoculation materials, easy operation, rapid disease onset, and almost no adverse effect on the host. It is particularly suitable for the resistance screening of all progeny and the early (seedling) phenotypic selection of resistant poplar clones in poplar stem disease resistance breeding. The "in vivo leaf inoculation method" holds significant promise in poplar breeding, tree pathology, and molecular biology research on tree stem diseases.

plant biology↗

In-silico Drug Repurposing pipeline for Epilepsy: Integrating Deep Learning and Structure-based Approaches

Due to considerable global prevalence and high recurrence rate, the pursuit of effective new medication for epilepsy treatment remains an urgent and significant challenge. Drug repurposing emerges as a cost-effective and efficient strategy to combat this disorder. This study leverages the transformer-based deep learning methods coupled with molecular binding affinity calculation to develop a novel in-silico drug repurposing pipeline for epilepsy. The number of candidate inhibitors against 24 target proteins encoded by gain-of-function (GOF) genes implicated in epileptogenesis ranged from zero to several hundreds. Our pipeline has repurposed the medications with most anti-epileptic drugs (AEDs) and nearly half psychiatric medications, highlighting the effectiveness of our pipeline. Furthermore, Lomitapide, a cholesterol-lowering drug, first emerged as particularly noteworthy, exhibiting high binding affinity for 10 targets and verified by molecular dynamics (MD) simulation and mechanism analysis. These findings provided a novel perspective on therapeutic strategies for other central nervous system (CNS) disease.

pharmacology and toxicology↗

Microglia promote extracellular matrix deposition and restrict excitatory synapse numbers in the mesolimbic dopamine system during healthy aging

Synapse dysfunction is tightly linked to cognitive changes during aging. Emerging evidence suggests that microglia and the extracellular matrix (ECM) can potently regulate synapse integrity and plasticity. Yet the brain ECM, and its relationship with microglia, synapses, and cognition during aging remains virtually unexplored. Using ECM-optimized proteomic workflows and histological analyses, we discovered striking regional differences in ECM composition and aging-induced ECM remodeling across key basal ganglia nuclei. Moreover, we combine two distinct behavioral classification strategies with fixed-tissue confocal imaging and proteomic analysis to identify robust relationships between the hyaluronan- and proteoglycan-rich ECM and cognitive aging phenotypes. Finally, we provide evidence that aging midbrain microglia lose capacity to interact with and regulate the ECM, and that these aging-associated microglial changes are accompanied by local ECM accumulation and worse behavioral performance. Together, these foundational observations implicate changing microglia-ECM-synapse interactions as a key determinant of cognitive functioning during healthy aging.

neuroscience↗

DNA methylation is linked to the monoallelic expression of MRP3, a diatom mating type determining gene

Diatoms are unicellular microalgae widely distributed in aquatic ecosystems. In diatoms, sexual reproduction is needed to counteract cell miniaturization imposed by the rigid silica shell, and only small cells, below a species-specific size threshold, are competent for sex. We performed a genome-wide Enzymatic Methyl-seq analysis in the heterothallic diatom Pseudo-nitzschia multistriata comparing cells of different size and opposite mating type (MT) to investigate potential epigenetic controls in life cycle transitions. We found an imprinting-like pattern of methylation at the sex locus: alleles of the gene responsible for the specification of the MT+, MRP3, are hypermethylated in MT- and differentially methylated in MT+, with transcription occurring only on the MT+ hypomethylated variant. The methylation pattern is overall stable over the P. multistriata life cycle. Absence of methylation in MRP3 is necessary for its expression but not sufficient, since large non-sexual cells have the same methylation profile of small sexual cells but do not express MRP3, suggesting that additional controls are involved in the mechanism of sex determination. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=166 SRC="FIGDIR/small/561864v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@ea2482org.highwire.dtl.DTLVardef@2d553org.highwire.dtl.DTLVardef@350aaorg.highwire.dtl.DTLVardef@1a4f2f6_HPS_FORMAT_FIGEXP M_FIG C_FIG The methylation profile of the mating type determining gene MRP3 of the diatom Pseudo-nitzschia multistriata is different between opposite mating types. Lack of methylation is necessary but not sufficient for MRP3 expression in the sexually competent MT+ strains. HighlightsO_LI- The mating type locus is differentially methylated in MT+ and MT- C_LIO_LI- DNA methylation is linked to MRP3 expression C_LIO_LI- DNA methylation does not play a role in the acquisition of sexual competence C_LI

genetics↗

Human brain state dynamics reflect individual neuro-phenotypes

Neural activity and behavior vary within an individual (states) and between individuals (traits). However, the mapping of state-trait neural variation to behavior is not well understood. To address this gap, we quantify moment-to-moment changes in brain-wide co-activation patterns derived from resting-state functional magnetic resonance imaging. In healthy young adults, we identify reproducible spatio-temporal features of co-activation patterns at the single subject level. We demonstrate that a joint analysis of state-trait neural variations and feature reduction reveal general motifs of individual differences, en-compassing state-specific and general neural features that exhibit day-to-day variability. The principal neural variations co-vary with the principal variations of behavioral phenotypes, highlighting cognitive function, emotion regulation, alcohol and substance use. Person-specific probability of occupying a particular co-activation pattern is reproducible and associated with neural and behavioral features. This combined analysis of statetrait variations holds promise for developing reproducible neuroimaging markers of individual life functional outcome.

neuroscience↗

Molecular Mechanism of PP2A/B55α Inhibition by IER5

PP2A serine/threonine phosphatases are heterotrimeric complexes that execute many essential physiologic functions. These activities are modulated by additional regulatory proteins, such as ARPP19, FAM122A, and IER5. Here, we report the cryoelectron microscopy structure of a complex of PP2A/B55 with the N-terminal structured region of IER5 (IER5-N50), which occludes a surface on B55 used for substrate recruitment, and show that IER5-N50 inhibits PP2A/B55 catalyzed dephosphorylation of pTau in biochemical assays. Mutations of full-length IER5 that disrupt its PP2A/B55 interface interfere with co-immunoprecipitation of PP2A/B55. These mutations and deletions that remove the nuclear localization sequence of IER5 suppress cellular events such as KRT1 expression that depend on association of IER5 with PP2A/B55. Querying the Alphafold2 predicted structure database identified SERTA domain proteins as high-confidence PP2A/B55-binding structural homologs of IER5-N50. These studies define the molecular basis of PP2A/B55 inhibition by IER5-family proteins and suggest a roadmap for selective pharmacologic modulation of PP2A/B55 complexes.

biochemistry↗

An oligodendrocyte silencer element underlies the pathogenic impact of lamin B1 structural variants

The role of non-coding regulatory elements and how they might contribute to tissue type specificity of disease phenotypes is poorly understood. Autosomal Dominant Leukodystrophy (ADLD) is a fatal, adult-onset, neurological disorder that is characterized by extensive CNS demyelination. Most cases of ADLD are caused by tandem genomic duplications involving the lamin B1 gene (LMNB1) while a small subset are caused by genomic deletions upstream of the gene. Utilizing data from recently identified families that carry LMNB1 gene duplications but do not exhibit demyelination, ADLD patient tissues, CRISPR modified cell lines and mouse models, we have identified a novel silencer element that is lost in ADLD patients and that specifically targets overexpression to oligodendrocytes. This element consists of CTCF binding sites that mediate three-dimensional chromatin looping involving the LMNB1 and the recruitment of the PRC2 repressor complex. Loss of the silencer element in ADLD identifies a previously unknown role for silencer elements in tissue specificity and disease causation.

genetics↗

Ancient Sheep Genomes reveal four Millennia of North European Short-Tailed Sheep in the Baltic Sea region

Sheep are among the earliest domesticated livestock species, with a wide variety of breeds present today. However, it remains unclear how far back this breed diversity goes, with formal documentation only dating back a few centuries. North European short-tailed breeds are often assumed to be among the oldest domestic sheep populations, even thought to represent relicts of the earliest sheep expansions during the Neolithic period reaching Scandinavia less than 6000 years ago. This study sequenced the genomes (up to 11.6X) of five sheep remains from the Baltic islands of Gotland and [A]land, dating from Late Neolithic ([~]4100 calBP) to historical times ([~]1600 CE). Our findings indicate that these ancient sheep largely possessed the genetic characteristics of modern North European short-tailed breeds, suggesting a substantial degree of long-term continuity of this breed type in the Baltic Sea region. Despite the wide temporal spread, population genetic analyses show high levels of affinity between the ancient genomes and they also exhibit higher genetic diversity when compared to modern breeds, implying a loss of diversity in recent centuries associated with breed formation. Finally, we see a potential signature of an even earlier, genetically different form of sheep in Scandinavia as these samples do not represent the first sheep in Northern Europe. Our results shed light on the development of breeds in Northern Europe specifically as well as the development of genetic diversity in sheep breeds, and their expansion from the domestication center in general.

evolutionary biology↗

Virological characteristics of the SARS-CoV-2 Omicron XBB.1.16 variant

At the end of March 2023, XBB.1.16, a SARS-CoV-2 omicron XBB subvariant, emerged and was detected in various countries. Compared to XBB.1.5, XBB.1.16 has two substitutions in the S protein: E180V is in the N-terminal domain, and T478R in the receptor-binding domain (RBD). We first show that XBB.1.16 had an effective reproductive number (Re) that was 1.27- and 1.17-fold higher than the parental XBB.1 and XBB.1.5, respectively, suggesting that XBB.1.16 will spread worldwide in the near future. In fact, the WHO classified XBB.1.16 as a variant under monitoring on March 30, 2023. Neutralization assays demonstrated the robust resistance of XBB.1.16 to breakthrough infection sera of BA.2 (18-fold versus B.1.1) and BA.5 (37-fold versus B.1.1). We then used six clinically-available monoclonal antibodies and showed that only sotrovimab exhibits antiviral activity against XBB subvariants, including XBB.1.16. Our results suggest that, similar to XBB.1 and XBB.1.5, XBB.1.16 is robustly resistant to a variety of anti-SARS-CoV-2 antibodies. Our multiscale investigations suggest that XBB.1.16 that XBB.1.16 has a greater growth advantage in the human population compared to XBB.1 and XBB.1.5, while the ability of XBB.1.16 to exhibit profound immune evasion is comparable to XBB.1 and XBB.1.5. The increased fitness of XBB.1.16 may be due to (1) different antigenicity than XBB.1.5; and/or (2) the mutations in the non-S viral protein(s) that may contribute to increased viral growth efficiency.

microbiology↗

AI-Designed, Mutation-Resistant Broad Neutralizing Antibodies Against Multiple SARS-CoV-2 Strains

In this study, we generated a Digital Twin for SARS-CoV-2 by integrating data and meta-data with multiple data types and processing strategies, including machine learning, natural language processing, protein structural modeling, and protein sequence language modeling. This approach enabled the computational design of broadly neutralizing antibodies against over 1300 different historical strains of SARS-COV-2 containing 64 mutations in the receptor binding domain (RBD) region. The AI-designed antibodies were experimentally validated in real-virus neutralization assays against multiple strains including the newer Omicron strains that were not included in the initial design base. Many of these antibodies demonstrate strong binding capability in ELISA assays against the RBD of multiple strains. These results could help shape future therapeutic design for existing strains, as well as predicting hidden patterns in viral evolution that can be learned by AI for developing future antiviral treatments.

bioinformatics↗