Biology subjects

Leung, D.

Publications and source records attributed to Leung, D..

11 recordsLinked to original sources

bioRxiv2025

Multi-scale machine learning model predicts muscle and functional disease progression in FSHD

Facioscapulohumeral muscular dystrophy (FSHD) is a genetic neuromuscular disorder characterized by progressive muscle degeneration with substantial variability in severity and progression patterns. FSHD is a highly heterogeneous disease; however, current clinical metrics used tracking disease progression lack sensitivity for personalized assessment, which greatly limits the design and execution of clinical trials. This study introduces a multi-scale machine learning framework leveraging whole-body magnetic resonance imaging (MRI) and clinical data to predict regional, muscle, joint, and functional progression in FSHD. The goal this work is to create a digital twin of individual FSHD patients that can be leveraged in clinical trials. Using a combined dataset of over 100 patients from seven studies, MRI-derived metrics--including fat fraction, lean muscle volume, and fat spatial heterogeneity at baseline--were integrated with clinical and functional measures. A three-stage random forest model was developed to predict annualized changes in muscle composition and a functional outcome (timed up-and-go (TUG)). All model stages revealed strong predictive performance in separate holdout datasets. After training, the models predicted fat fraction change with a root mean square error (RMSE) of 2.16% and lean volume change with a RMSE of 8.1ml in a holdout testing dataset. Feature analysis revealed that metrics fat heterogeneity within muscle predicts muscle-level progression. The stage 3 model that combined functional muscle groups and predicted change in TUG with a RMSE of 0.6 seconds, in the holdout testing dataset. This study demonstrates the machine learning models incorporating individual muscle and performance data can effectively predict MRI disease progression and functional performance of complex tasks, addressing the heterogeneity and nonlinearity inherent in FSHD. Further studies incorporating larger longitudinal cohorts as well as comprehensive clinical and functional measures will allow for expanding and refining this model. As many neuromuscular diseases are characterized by varability and heterogeneity similar to FSHD, such approaches have broad applicability.

bioengineering↗

bioRxiv2024

Single-cell image-based genetic screens systematically identify regulators of Ebola virus subcellular infection dynamics

Ebola virus (EBOV) is a high-consequence filovirus that gives rise to frequent epidemics with high case fatality rates and few therapeutic options. Here, we applied image-based screening of a genome-wide CRISPR library to systematically identify host cell regulators of Ebola virus infection in 39,085,093 million single cells. Measuring viral RNA and protein levels together with their localization in cells identified over 998 related host factors and provided detailed information about the role of each gene across the virus replication cycle. We trained a deep learning model on single-cell images to associate each host factor with predicted replication steps, and confirmed the predicted relationship for select host factors. Among the findings, we showed that the mitochondrial complex III subunit UQCRB is a post-entry regulator of Ebola virus RNA replication, and demonstrated that UQCRB inhibition with a small molecule reduced overall Ebola virus infection with an IC50 of 5 M. Using a random forest model, we also identified perturbations that reduced infection by disrupting the equilibrium between viral RNA and protein. One such protein, STRAP, is a spliceosome-associated factor that was found to be closely associated with VP35, a viral protein required for RNA processing. Loss of STRAP expression resulted in a reduction in full-length viral genome production and subsequent production of non-infectious virus particles. Overall, the data produced in this genome-wide high-content single-cell screen and secondary screens in additional cell lines and related filoviruses (MARV and SUDV) revealed new insights about the role of host factors in virus replication and potential new targets for therapeutic intervention.

microbiology↗

bioRxiv2023

OsUVR8b, rather than OsUVR8a, plays a predominant role in rice UVR8-mediated UV-B response.

UV RESISTANCE LOCUS 8 (UVR8) has been identified in Arabidopsis thaliana as the receptor for UV-B radiation mediating photomorphogenic responses and acclimation to UV-B radiation. However, UVR8-mediated UV-B signaling pathways in rice, that has two proteins (UVR8a and UVR8b) with homology to AtUVR8, remain largely unknown. In this study, UVR8a and UVR8b were found to be expressed mainly in rice leaves and leaf sheaths, while the level of UVR8b was higher than that of UVR8a. In agreement with prior studies on AtUVR8, uvr8b and uvr8a uvr8b rice mutants exposed to UV-B showed reduced UVB-induced growth inhibition and upregulation of CHS and HY5 transcripts along with acclimation to UV-B, overexpressing UVR8a or UVR8b enhanced UV-B-induced growth inhibition and acclimation to UV-B, compared to wild-type plants. UV-B was able to enhance the interaction between CONSTITUTIVE PHOTOMORPHOGENESIS1 (COP1) with UVR8a/UVR8b, whereas the interaction intensity of REPRESSOR OF UV-B PHOTOMORPHOGENESIS2 (RUP2) with UVR8a was significantly higher than that with UVR8b. In addition, UVR8a and UVR8b were also found in the nucleus and cytoplasm, but OsUVR8 proteins were localized in nucleus in the absence of UV-B. The level of OsUVR8 monomer showed an invisible change in the leaves of rice seedlings transferred from white light to white light supplemented with UV-B, even UV-B can weaken the interactions of UVR8a or/and UVR8b. Therefore, both UVR8a and UVR8b, that have different location and response modes with Arabidopsis UVR8, function in the response of rice to UV-B radiation, whereas UVR8b plays a predominant role in this process.

plant biology↗

bioRxiv2022

Injectable polymer-nanoparticle hydrogel for the sustained intravitreal delivery of bimatoprost

Vision impairment resulting from chronic eye diseases, such as macular degeneration and glaucoma, severely impacts patients quality of life and poses an immense global financial burden. Current standard of care for such diseases includes daily eye drops or frequent intravitreal (ITV) injections, which are burdensome treatment modalities resulting in low patient compliance. There remains a growing need for easily administered long-acting delivery technologies for prolonging exposure of ocular therapeutics with each administration. Here, we deploy a supramolecular polymer-nanoparticle (PNP) hydrogel for ITV delivery of the glaucoma drug bimatoprost. PNP hydrogels are shear-thinning and self-healing, key properties for injectability, and enable slow release of molecular cargo in vitreous humor (VH) mimics. An in vivo study in New Zealand white rabbits demonstrated intravitreally injected PNP hydrogels form depots that degrade slowly over time, maintaining detectable levels of bimatoprost in the VH up to eight weeks following injection. Ophthalmic examinations and histopathology identified a mild foreign body response (FBR) to the hydrogel, characterized by rare clusters of foamy macrophages and giant cells associated with minimal, patchy fibroplasia. This work shows that PNP hydrogels exhibit numerous desirable traits for sustained drug delivery and further work will be necessary to optimize tolerability in the eye.

bioengineering↗

bioRxiv2022

Oropouche orthobunyavirus infection is mediated by the cellular host factor Lrp1

Oropouche orthobunyavirus (OROV; Peribunyaviridae) is a mosquito-transmitted virus that causes widespread cases of human febrile illness in South America, with occasional progression to neurologic effects. Host entry factors mediating cellular entry of OROV are undefined. Here, we show that OROV requires the host protein low density lipoprotein-related protein 1 (Lrp1) for cellular infection. Cells from evolutionarily distinct species lacking Lrp1 were less permissive to OROV infection than cells with Lrp1. Treatment of cells with either the high-affinity Lrp1 ligand receptor-associated protein (RAP) or recombinant ectodomain truncations of Lrp1 significantly reduced OROV infection. Thus, Lrp1 is an important host factor required for infection of cells by OROV. Taken together with our results showing that Lrp1 is a newly identified receptor for Rift Valley fever virus (RVFV), Lrp1 may play a broader role in cellular infection by bunyaviruses than previously appreciated.

microbiology↗

bioRxiv2020

Tetravalent SARS-CoV-2 Neutralizing Antibodies Show Enhanced Potency and Resistance to Escape Mutations

Neutralizing antibodies (nAbs) hold promise as effective therapeutics against COVID-19. Here, we describe protein engineering and modular design principles that have led to the development of synthetic bivalent and tetravalent nAbs against SARS-CoV-2. The best nAb targets the host receptor binding site of the viral S-protein and its tetravalent versions can block entry with a potency that exceeds the bivalent nAbs by an order of magnitude. Structural studies show that both the bivalent and tetravalent nAbs can make multivalent interactions with a single S-protein trimer, observations consistent with the avidity and potency of these molecules. Significantly, we show that the tetravalent nAbs show much increased tolerance to potential virus escape mutants. Bivalent and tetravalent nAbs can be produced at large-scale and are as stable and specific as approved antibody drugs. Our results provide a general framework for developing potent antiviral therapies against COVID-19 and related viral threats, and our strategy can be readily applied to any antibody drug currently in development.

synthetic biology↗

bioRxiv2020

Situation of antibiotic resistance in Bangladesh and its association with resistance genes for horizontal transfer

The study investigated the spectrum of antibiotic resistance and the associated genes for aminoglycoside, macrolide and ESBL class of antibiotics using clinical isolates. A total of 430 preserved bacterial strains (Acinetobacter baumannii, n= 20; Pseudomonas aeruginosa, n= 26; Klebsiella pneumoniae, n= 42; E.coli, n= 85; Staphylococcus aureus, n= 84; Salmonella Typhi, n= 82; Enterococcus spp., n= 27; Streptococcus pneumoniae, n= 36 and CNS, n= 28) were examined. The strains were isolated from patients admitted to various tertiary hospitals of Dhaka city between 2015 and 2019 with either acute respiratory infections, wound infections, typhoid fever or diarrhea. The isolates were reconfirmed by appropriate microbiological and biochemical methods. Antimicrobial susceptibility tests were done using Kirby-Bauer disk diffusion approach. PCR amplification using resistance gene-specific primers for aminoglycoside, macrolide and ESBL class of antibiotics was done and the amplified products were confirmed by Sanger sequencing. Of the total isolates, 53% came out as MDR with 96.6% of E. coli and 90% of Staphylococcus aureus. There was a year-wise gradual increase of MDR isolates from 2015-2018 and by 2019 the increase in MDR isolates became almost 2-fold compared to 2015. Among the five ESBL genes investigated, CTXM-1 came out as the most prevalent (63%) followed by NDM-1 (22%) and E. coli isolates were the predominant reservoir of these genes. ErmB (55%) was the most frequently detected macrolide resistance gene, whereas aac(6)-Ib (35.44%) was the most prevalent aminoglycoside resistance gene and these genes were most prevalent in E. coli and P. aeruginosa isolates, respectively. CTXM-1 and ErmB (16.66%) were the most frequent partners of coexistence followed by CTXM-1 and aac(3)-II.

microbiology↗

bioRxiv2019

Replication timing maintains the global epigenetic state in human cells.

DNA is replicated in a defined temporal order termed the replication timing (RT) program. RT is spatially segregated in the nucleus with early/late replication corresponding to Hi-C A/B chromatin compartments, respectively. Early replication is also associated with active histone modifications and transcriptional permissiveness. However, the mechanistic interplay between RT, chromatin state, and genome compartmentalization is largely unknown. Here we report that RT is central to epigenome maintenance and compartmentalization in both human embryonic stem cells (hESCs) and cancer cell line HCT116. Knockout (KO) of the conserved RT control factor RIF1, rather than causing discrete RT switches as previously suspected, lead to dramatically increased cell to cell heterogeneity of RT genome wide, despite RIF1s enrichment in late replicating chromatin. RIF1 KO hESCs have a nearly random RT program, unlike all prior RIF1 KO cells, including HCT116, which show localized alterations. Regions that retain RT, which are prevalent in HCT116 but rare in hESCs, consist of large H3K9me3 domains revealing two independent mechanisms of RT regulation that are used to different extents in different cell types. RIF1 KO results in a striking genome wide downregulation of H3K27ac peaks and enrichment of H3K9me3 at large domains that remain late replicating, while H3K27me3 and H3K4me3 are re-distributed genome wide in a cell type specific manner. These histone modification changes coincided with global reorganization of genome compartments, transcription changes and a genome wide strengthening of TAD structures. Inducible degradation of RIF1 revealed that disruption of RT is upstream of genome compartmentalization changes. Our findings demonstrate that disruption of RT leads to widespread epigenetic mis-regulation, supporting previously speculative models in which the timing of chromatin assembly at the replication fork plays a key role in maintaining the global epigenetic state, which in turn drives genome architecture.

molecular biology↗

bioRxiv2019

A DNA Methylation Fingerprint of Cellular Senescence

Recent years have witnessed an influx of therapies aimed at targeting the biological aging process. While many hold promise for potentially delaying the simultaneous onset of multiple chronic conditions, a major hurdle in developing interventions to slow human aging is the lack of reliable and valid endpoints from which to evaluate potential candidates. The aim of this study was to develop a biomarker that could serve as a potential endophenotype in evaluation of one of the most promising and exciting aging therapeutics being developed--senolytics. Senolytics are compounds which selectively clear senescent cells by targeting anti-apoptotic pathways. Using DNAm data from fibroblasts and mesenchymal stromal cells (MSC) in culture, we developed a predictor of cellular senescence that related to three distinct senescence inducers (replicative, oncogene induced (OIS), and ionizing radiation (IR)). Our measure, termed DNAmSen, showed expected classification of validation data from embryonic stem cells (ESC), induced pluripotent stem cells (iPSC), and near senescent cells in culture. Further, using bulk data from whole blood, peripheral tissue samples, and postmortem tissue, we observed robust correlations between age and DNAmSen. We also observed age adjusted associations between DNAmSen and idiopathic pulmonary fibrosis (IPS), COPD, lung cancer, and Werner syndrome compared to controls. When characterizing the 88 CpGs in the DNAmSen measure, we observed a enrichment for those located in enhancer regions and regulatory regions marked by DNase I hypersensitive sites (DHSs). Interestingly most of the CpGs were observed to be moderately hypomethyled in early passage cells, yet exhibited further hypomethylation upon induction of cellular senescence, suggesting senescence is accompanied by programmatic alterations to the epigenome, rather than entropic drift.

systems biology↗

bioRxiv2019

Comparative analysis of epigenetic aging clocks from CpG characteristics to functional associations

To date, a number of epigenetic clocks have been developed using DNA methylation data, aimed at approximating biological aging in multiple tissues/cells. However, despite the assumption that these clocks are meant to capture the same phenomenon-aging, their correlations with each other are weak, and there is a lack of consistency in their associations with outcomes of aging. Therefore, the goal of this study was to compare and contrast the molecular characteristics and functional associations of 11 existing epigenetic clocks, using data from diverse human tissue and cell types. Results suggest that the CpGs comprised in the various clocks differ in regards to the consistency of their age correlations across tissues/cells. Using microarray expression data from purified CD14+ monocytes, we found that six clocks--Yang, Hannum, Lin, Levine, Horvath1, and Horvath2--has relatively similar transcriptional profiles. Network analysis revealed nine co-expression modules, most of which display robust correlations across various clocks. One significant module--turquoise is involved in mitochondrial translation, gene expression, respiratory chain complex assembly, and oxidative phosphorylation. Finally, using data from 143B cells with chronically depleted mtDNA (rho0) and 143B controls, we found that rho0 cells have more than a three-standard deviation increase in epigenetic age for Levine (p=0.006), Lin (p=0.012), and Yang (p=0.013). In summary, these results demonstrate the shared and contrasting features of existing epigenetic clocks, in regards to the CpG characteristic, tissue specificity, and co-regulatory gene network signatures, and suggesting a link between two hallmarks of aging--epigenetic alterations and mitochondrial dysfunction.

bioinformatics↗

bioRxiv2018

Microbiome and Antimicrobial Resistance Gene Dynamics in International Travelers

We engaged metagenomic next generation sequencing to longitudinally assess the gut microbiota and antimicrobial resistomes of international travelers to understand global exchange of resistant organisms. Travel resulted in an increase in antimicrobial resistance genes and a greater proportion of Escherichia species within gut microbial communities without impacting diversity.

microbiology↗