Biology subjects

Mohamed, A.

Publications and source records attributed to Mohamed, A..

At least 19 recordsLinked to original sources

bioRxiv2026

The Effects of Phosphorylation on the Structure and Function of Motif A, an Intrinsically Disordered Region within SIRT1

The NAD+ dependent deacetylase sirtuin-1 (SIRT1) is known to elicit cellular defenses against aging, cancer, and other aberrant pathologies. Previous studies have identified an intrinsically disordered region of SIRT1 comprised of N-terminal residues 1-52, herein referred to as motif A, which activates SIRT1 activity, likely through intramolecular interactions. Additionally, phosphorylation of N-terminal residues Ser27 and Ser47 has been shown to be important for regulating SIRT1 activity and stability. The lack of in vitro characterization of these effects hampers our further understanding of the role of motif A in SIRT1 regulation. In this study, we elucidate the role phosphorylation plays in motif As structure as well as its regulatory effects on SIRT1 activity against Ac-p65. We find that phosphomimetic mutation at Ser27 significantly increases the activation effect of motif A towards SIRT1. This result is supported by molecular dynamics simulations of the phosphomimetics, which reveal stabilization of different transient structures for motif A depending on whether Ser27 and Ser47 have been modified. A key finding suggested by this study is that phosphorylation of S27 appears to activate SIRT1 by causing motif A, which is intrinsically disordered in the WT, to fold into an ordered structure. This conclusion is based on both the experimental findings and simulation results. These findings contribute to our understanding of SIRT1 regulation, specifically the role played by phosphorylation within the N-terminal disordered region.

biochemistry↗

bioRxiv2026

Hyperactivated YAP1 Drives an Invasive EMT Subtype of Cervical Squamous Cell Carcinoma

Cervical cancer (CVC) is classically understood as an HPV-driven disease in which high-risk HPV infects cervical basal epithelial cells, induces neoplastic transformation, and drives upward epithelial expansion, pathogenic events underlying the success of cytology- and HPV-based screening. With widespread HPV vaccination and screening, the WHO has launched the CVC elimination initiative and believes that CVC will be the first cancer that would be eliminated as a public health problem. However, statistics showed that CVC remains the most common gynecologic malignancy worldwide, and in the United States, where HPV testing and Pap smears have reached near-maximal implementation, the CVC mortality rate has plateaued for more than two decades. These epidemiologic trends suggest the existence of a subset of CVC that can escape current screening strategies. Here, we demonstrate that hyperactivation of YAP1 caused by disruption of Hippo-YAP signaling is sufficient to induce a subtype of HPV-independent invasive CVC that lacks surface lesions and therefore evades HPV- and cytology-based detection. Using single-cell RNA sequencing combined with high-resolution spatial transcriptomics, we define the cellular architecture, molecular pathways, and immune microenvironment underlying this invasive subtype. We show that YAP1-driven tumors adopt an EMT-high transcriptional state and selectively recruit immunosuppressive myeloid-derived suppressor cells that functionally interact with cancer cells to promote invasion and progression. Our findings suggest that targeting the disrupted Hippo signaling may offer a new strategy to prevent the subset of invasive CVC that current HPV- and Pap-based programs cannot detect, an essential step toward achieving global CVC elimination.

cancer biology↗

bioRxiv2025

Genomic and Transcriptomic Landscapes of MEN1-Wild-Type Low-Grade Metastatic Pancreatic NETs Uncover Key Oncogenic Drivers and Targetable Pathways

Sporadic pancreatic neuroendocrine tumors (pNETs) with wild type MEN1 represent a major yet largely ignored subset whose biology and metastatic potential remain poorly understood. Because metastasis can occur despite low histologic grade and modest mutational burden, we hypothesized that metastatic competence in MEN1-wild-type pNETs reflects quantitative reinforcement of shared oncogenic pathways rather than distinct mutational processes. We profiled 75 primary low-grade pNETs by whole-exome and RNA sequencing, including 25 percent with lymph node and/or liver metastasis, and integrated genomic and transcriptomic data to connect pathway lesions with expression state. Metastatic tumors showed a slight increase in mutation frequency but conserved base-substitution spectra relative to non-metastatic cases, and adverse clinicopathologic features were enriched in Grade 2 disease. Aggregating alterations to pathways revealed broad convergence on canonical networks, with transcriptomic analyses demonstrating cohort-wide enrichment of Calcium, WNT, and KRAS/PI3K-AKT programs in metastasis. Intersection of significantly mutated genes with differentially expressed genes identified a focused 29-gene overlap, including RYR1 and ZNF273, that marks these convergent axes and distinguishes metastatic from non-metastatic tumors. Gene set enrichment confirmed preferential activation of Calcium, WNT, and PI3K-AKT signaling in metastatic tumors, consistent with a network-intensity model of progression. Finally, upstream-regulator analysis (iPathwayGuide) and gene-centric perturbation mapping (Gene2Drug) nominated candidate targeted and repurposable agents predicted to reverse the metastatic expression phenotype and flagged drugs unlikely to provide benefit, yielding a prioritized, testable therapeutic shortlist which includes fasudil and spaglumic acid. Convergent, domain-specific mutational patterns in highly mutated genes such as ZNF273 and CLCA1 define a molecular signature that could stratify metastatic risk in low-grade pNETs. Collectively, our data reframe metastasis in MEN1-wild-type low-grade pNETs as a property of pathway state rather than mutation quantity and provide a translational blueprint for biomarker-guided therapy development focused on Calcium, WNT, and KRAS/PI3K hubs.

cancer biology↗

bioRxiv2025

Prevalence of zoonotic hepatic nematode varies with small mammal community diversity across a heterogenous landscape in Eastern Uganda

Identifying key drivers of pathogen infection prevalence and intensity in wildlife is essential to understand disease dispersal and transmission. Calodium hepatica (syn. Capillaria hepatica) is a generalist nematode that infects liver parenchyma of mammals worldwide and is capable of human infections. Prevalence ranges from 0-100% in wildlife, often varying across small geographic areas, making it an ideal parasite for understanding ecological drivers of variation. Here, we quantify prevalence of Calodium hepatica and present initial surveys of synanthropic small mammals in four villages representing differing land cover. Cross-sectional rodent trapping was conducted within and around households over consecutive dry seasons in Eastern Uganda. 18s rRNA gene of C. hepatica was amplified and a sub-set of PCR products sequenced to confirm presence of C. hepatica. Landscape structural diversity was classified by tree crown density and mean canopy height derived from 30m LiDAR data within a 0.5km buffer. Multivariable binomial generalised linear models were fit to C. hepatica prevalence. C. hepatica infection was common (overall 34.5%, CI95% 27.9-41.0) and found in rodent and shrew species inside and outside residences. We observe village-level differences in prevalence (18.2%-75.0%), with higher C. hepatica prevalence associated with higher relative proportion of Rattus rattus to other species (aOR=2.22 CI95% 1.30-3.85). Host diversity appears to be protective against parasite prevalence. Differences in molecular and macroscopy identification highlight challenges in diagnosis and a need for more specialized molecular tools. Further investigation is required to understand individual host and community variation in pathogen infection intensity and implications for zoonotic risk. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/674808v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@e9cfdaorg.highwire.dtl.DTLVardef@4d0f6dorg.highwire.dtl.DTLVardef@12fe43dorg.highwire.dtl.DTLVardef@1318d83_HPS_FORMAT_FIGEXP M_FIG C_FIG Key FindingsO_LIZoonotic reservoirs, including Rattus rattus, Mastomys erythroleucus and Crocidura olivieri, are abundant in human-modified habitats and show elevated levels of household incursion C_LIO_LIHigh prevalence of Calodium hepatica, a nematode endoparasite, was identified in a range of small mammal species C_LIO_LIHigher proportion of native small mammal species relative to Rattus rattus appears protective against zoonotic pathogen load, with higher village-level C. hepatica prevalence in ecologically depleted sites C_LIO_LISmall-holder agriculture may provide a dilution effect through secondary wildlife support and small mammal competition, while dense village settings potentiate C. hepatica prevalence C_LI

ecology↗

bioRxiv2025

Dolutegravir Developmental Toxicity is Mitigated by Magnesium and Folate in Zebrafish Embryos

Integrase-strand-transfer inhibitors have transformed HIV therapy, yet the widely prescribed drug dolutegravir (DTG) has been linked to developmental toxicity and its teratogenic mechanism remains uncertain. Here we use zebrafish to dissect DTG toxicity during early vertebrate development. DTG exposure from 2-4 h post-fertilization (hpf) to 24 hpf produced high mortality and abnormal morphology; co-treatment with folic acid or 5-methyltetrahydrofolate partially restored normal morphology, whereas calcium had no effect. Strikingly, supplementation with magnesium (Mg) rescued DTG-exposed embryos almost as effectively as folate, implicating magnesium availability in protection. In competitive binding assays, Mg increased binding of folate to purified folate receptor (FOLR1) by 30% in the presence of DTG. Maternal-zygotic zebrafish folr1 mutant embryos contained significantly less endogenous folate than wild-type embryos yet displayed marked hypersensitivity to DTG that could not be mitigated by folate supplementation. Critically, magnesium supplementation partially rescued DTG toxicity in folr1 mutants, indicating a Folr1-independent component and placing the free DTG vs Mg-bound DTG balance upstream of folate transport. These results support a model in which free DTG antagonizes FOLR1, and Mg modifies DTG developmental toxicity by both FOLR1 dependent and independent processes. Our work identifies magnesium status as a modifiable determinant of DTG teratogenicity and provides a proof-of-concept zebrafish model that could be adapted for rapid in vivo screening of integrase inhibitors for developmental phenotypes.

developmental biology↗

bioRxiv2025

Machine Learning-Driven Drug Repurposing for KRAS G12C and KRAS G12D Inhibition

KRAS is a predominant oncogenic driver across multiple cancers, long considered "undruggable" due to its high nucleotide affinity and lack of classical binding pockets. Although recent advances have led to covalent inhibitors like Sotorasib and Adagrasib for the KRAS G12C mutation, effective therapies for other common variants--most notably KRAS G12D, which is highly prevalent in aggressive pancreatic cancers--remain limited. In this study, we employ machine learning to identify potential inhibitors for both KRAS G12D and G12C by screening FDA-approved compounds from the ChEMBL database. Random Forest and Neural Network models were trained on binding affinity data from three BindingDB datasets: wild-type KRAS GTPase, KRAS G12C, and KRAS G12D. Our models identified high-affinity candidates including anti-cancer kinase inhibitors (e.g., Cobimetinib, Gilteritinib) as well as drugs from other categories (e.g., Bromocriptine, Cefepime). By incorporating atomic hybridization as a feature, we aim to capture the effects of induced polarization, potentially improving prediction accuracy. Despite modest agreement across models, our approach highlights several promising candidates--such as Acalabrutinib, which has prior evidence of G12C activity--for further investigation. These results offer a data-driven foundation for experimental validation and the future development of targeted KRAS therapies.

cancer biology↗

bioRxiv2025

Fucoidans are senotherapeutics that enhance SIRT6-dependent DNA repair

Aging is marked by the accumulation of senescent cells (SnCs), which contribute to tissue dysfunction and age-related diseases. Senotherapeutics, including senolytics which specifically induce lysis of SnCs and senomorphics, which suppress the senescence phenotype, represent promising therapeutic interventions for mitigating age-related pathologies and extending healthspan. Using a phenotypic-based senescent cell screening assay, we identified fucoidans, a class of sulfated polysaccharides derived from brown algae and seaweed, as novel senotherapeutics. In particular, fucoidan from Fucus vesiculosus (Fucoidan-FV) displayed potent senomorphic activity in different types of SnCs, reduced senescence in multiple tissues in aged mice, and extended healthspan in a mouse model of accelerated aging. Fucoidan-FV also enhanced the deacetylation and mono-ADP-ribosylation (mADPr) activity of SIRT6 and improved DNA repair and reduced senescence, in part, through SIRT6-dependent pathways. In addition, Fucoidan-FV downregulated genes associated with inflammation, Wnt signaling, and ECM remodeling pathways in SnCs and increased expression of genes involved with DNA repair. These findings support the translational potential of fucoidans as novel senotherapeutics that also are able to improve SIRT6-mediated DNA repair.

cell biology↗

bioRxiv2025

The role of induced polarization in drug discovery applications

Induced polarization plays a pivotal role in ligand-protein binding by enhancing both the specificity and strength of molecular interactions. As a ligand approaches a protein, their respective electronic clouds redistribute in response to each others electrostatic fields--a phenomenon governed by induced polarization. The response of a molecules electron density to an external field is quantitatively described by its polarizability tensor. In this study, we calculated polarizability tensors for thousands of drug-like molecules from the CHEMBL database, focusing on compounds targeting the Thrombin, Estrogen Receptor alpha, and Phosphodiesterase 5A proteins using Density Functional Theory (DFT). We show that a machine learning model based on atomic hybridization accurately predict the polarizabilities eigenvalues, calculated with DFT. Then, we build a neural network and random forest models to predict the IC50s based on the same features. The success of these models, despite utilizing a limited number of features, underscores the critical role of induced polarizabilities in determining binding energies.

bioinformatics↗

bioRxiv2024

Sleep patterns predicting stress resilience are dependent on sex

Sleep disturbances and stress have a well-established link with neuropsychiatric illness; however, the nature of this relationship remains unclear. Recently, studies using the mouse social-defeat stress model revealed a causal role for non-rapid eye movement (NREM) sleep in the maladaptive behavioral responses to stress. These results suggest a novel function for NREM sleep; as a response by cortical neurons to mitigate the maladaptive effects of stress. A major limitation in many social defeat studies has been the exclusion of females. Women exhibit a greater prevalence of both affective disorders and sleep disturbances compared to men, thus there is a clear need to understand sleep - stress interactions in females. The present study adapts recently developed female social-defeat stress models to allow social-defeat and EEG in male - female pairs. Our findings duplicate the behavioral responses that occur in other female, nondiscriminatory, and male models of social-defeat stress. Analysis of electroencephalographic (EEG) recordings, before exposure to stress, reveal that resilience is associated with differences in both NREM and REM sleep that are dependent on sex. After social defeat stress, NREM sleep was increased only in resilient males. In females, susceptibility to stress was associated with increased durations in NREM-sleep bouts. A potential cause of these sleep differences was also identified prior to stress exposure, sex differences in recovery from NREM-sleep loss; thus, suggesting an underlying sex-difference in the homeostatic process regulating sleep interactions with social-defeat stress. These findings suggest that NREM sleep quality is lower in resilient females, whereas the amount of REM sleep is decreased in susceptible females--when compared to males of the same behavioral phenotype. Overall, our findings reveal sexual dimorphism in both the sleep characteristics predicting resilience and sleep changes induced by social-defeat stress.

neuroscience↗

bioRxiv2024

The toxic effects of lead nitrate on human keratinocytes (HaCaT).

This study investigated the cytotoxicity, genotoxicity, oxidative stress, and mitochondrial toxicity in human keratinocytes (HaCaT) caused by lead nitrate. An increase in lead nitrate concentration (50-800 {micro}M) showed a decrease in cell viability and the IC50 concentration was found to be 385.7 {micro}M. Lead nitrate at 250 {micro}M was also found to decrease the clonogenic potential, produce an increased number of binucleated cells with a micronucleus, increase the olive tail movement, reduce the thiol protein content, increase the intracellular and mitochondrial ROS levels, increase the mitochondrial mass and mitochondrial membrane potential. Which showed that Lead nitrate does indeed show cytotoxic, genotoxic effects as well as increase oxidative stress and alter mitochondrial functions. HIGHLIGHTSO_LILead nitrate causes cytotoxicity in keratinocytes with an IC50 conc. of 385.7 {micro}M. C_LIO_LIExposure to lead nitrate showed a significant increase in DNA damage. C_LIO_LILead nitrate increased the mitochondrial membrane potential and mass. C_LI

cell biology↗

bioRxiv2024

Evolutionary history and rhizosphere microbial community composition in domesticated hops (Humulus lupulus L.)

Humulus lupulus L., commonly known as hops, is a perennial crop grown worldwide and is well known for its pharmacological, commercial, and most importantly brewing applications. For hundreds of years, hops have undergone intense artificial selection with over 250 cultivated varieties being developed worldwide, all displaying differences in key characteristics such as bitter acid concentrations, flavor and aroma profiles, changes in photoperiod, growth, and pathogen/pest resistances. Previous studies have individually explored differences between cultivars, aiming to identify markers that can quickly and cost-effectively differentiate between cultivars. However, little is known about their evolutionary history and the variability in their associated rhizospheric microbial communities. Coupling phenotypic, genomic, and soil metagenomic data, our study aims to explore the global population structure and domestication history of 98 hops cultivars. Additionally, we assessed differences in growth rates, rates of viral infection, usage of dissolvable nitrogen, and soil microbial community compositions between US and non-US based cultivars. Contrary to previous studies, our study revealed that worldwide hop cultivars cluster into four primary subpopulations; Central European, English, and American ancestry as previously reported, and one new group, the Nobles, revealing further substructure amongst Central European cultivars. Modeling the evolutionary history of domesticated hops reveals an early divergence of the common ancestors of modern US cultivars around 2800 ybp, and more recent divergences with gene flow across English, Central European, and Noble cultivars, reconciled with key events in human history and migrations. Furthermore, cultivars of US origin were shown to overall outperform non-US cultivars in both growth rates and usage of dissolvable nitrogen and display novel microbial composition.

evolutionary biology↗

bioRxiv2024

Development of novel flavonoid senolytics through phenotypic drug screening and drug design

Accumulation of senescent cells drives aging and age-related diseases. Senolytics, which selectively kill senescent cells, offer a promising approach for treating many age-related diseases. Using a senescent cell-based phenotypic drug discovery approach that combines drug screening and drug design, we developed two novel flavonoid senolytics, SR29384 and SR31133, derived from the senolytic fisetin. These compounds demonstrated enhanced senolytic activities, effectively eliminating multiple senescent cell types, reducing tissue senescence in vivo, and extending healthspan in a mouse model of accelerated aging. Mechanistic studies utilizing RNA-Seq, machine learning, network pharmacology, and computational simulation suggest that these novel flavonoid senolytics target PARP1, BCL-xL, and CDK2 to induce selective senescent cell death. This phenotype-based discovery of novel flavonoid senolytics, coupled with mechanistic insights, represents a key advancement in developing next-generation senolyticss with potential clinical applications in treating aging and age-related diseases.

cell biology↗

bioRxiv2024

Identification of lipid senolytics targeting senescent cells through ferroptosis induction

Cellular senescence is a key driver of the aging process and contributes to tissue dysfunction and age-related pathologies. Senolytics have emerged as a promising therapeutic intervention to extend healthspan and treat age-related diseases. Through a senescent cell-based phenotypic drug screen, we identified a class of conjugated polyunsaturated fatty acids, specifically -eleostearic acid and its methyl ester derivative, as novel senolytics that effectively killed a broad range of senescent cells, reduced tissue senescence, and extended healthspan in mice. Importantly, these novel lipids induced senolysis through ferroptosis, rather than apoptosis or necrosis, by exploiting elevated iron, cytosolic PUFAs and ROS levels in senescent cells. Mechanistic studies and computational analyses further revealed their key targets in the ferroptosis pathway, ACSL4, LPCAT3, and ALOX15, important for lipid-induced senolysis. This new class of ferroptosis-inducing lipid senolytics provides a novel approach to slow aging and treat age-related disease, targeting senescent cells that are primed for ferroptosis.

cell biology↗

bioRxiv2024

Endothelial cell dysfunction and retinal arteriolar narrowing in young adults with elevated blood pressure

BackgroundYoung-adults with endothelial cell dysfunction are more likely to develop elevated blood pressure. We tested the hypothesis that this relates to development of structural microvascular impairments by studying associations between circulating endothelial colony-forming cell (ECFC) dysfunction and microvascular markers, as well as identifying related endothelial molecular mechanisms. MethodsPeripheral blood ECFCs were isolated from 32 subjects (53% men, 28{+/-}4 years old) using the Ficoll density gradient centrifugation method. Participants with blood pressure [≥]120/80 mm Hg were included in the elevated blood pressure (BP) group, whereas [≤]120/80 mm Hg were classed as normotensive. Retinal microvasculature was assessed by Static Retinal Vessel Analyzer (SVA-T). ResultsSubjects with elevated BP had impaired in vitro ECFC colony-forming growth, cell proliferation and angiogenesis assessed by tube formation potential. There was a graded inverse association between ECFC colony-forming capacity (days taken for ECFC colony growth) and retinal arteriolar diameter, as well as arteriolar/venular ratio. Proteomic analysis of ECFCs identified differences in extracellular matrix organization, blood coagulation, exocytosis and vesicle transport proteins in subjects with elevated blood pressure, revealing the adaptor protein GRB2 as a potential link between endothelial cell and microvascular abnormalities. ConclusionsEndothelial cell dysfunction associates with retinal arteriolar narrowing in men and women with elevated blood pressure. Endothelial molecular mechanisms linked to reduced adaptive postnatal angiogenesis capacity, rather than vascular development, may contribute to early microvascular changes. HIGHLIGHTSO_LISubjects with elevated blood pressure had impaired in vitro endothelial cell growth and angiogenesis in comparison to normotensive subjects. C_LIO_LIThere was an association between impaired endothelial cell growth capacity and reduced retinal arteriolar diameter. C_LIO_LIDifferent endothelial proteome signatures were identified, revealing the adaptor protein GRB2 as a potential link between endothelial and microvascular abnormalities in subjects with elevated blood pressure. C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/603349v1_ufig1.gif" ALT="Figure 1"> View larger version (71K): org.highwire.dtl.DTLVardef@9c28aborg.highwire.dtl.DTLVardef@3212a9org.highwire.dtl.DTLVardef@16755f9org.highwire.dtl.DTLVardef@13d5341_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

mastR: Marker Automated Screening Tool for multi-omics data

MotivationBiomarker discovery and utilization is important and offers insight into potential underlying mechanisms of disease. Existing marker identification methods primarily focus on single cell RNA sequencing (scRNA-seq) data, with no specific automated methods designed to learn from the bulk RNA-seq data. Furthermore, when adapting scRNA-seq methods to bulk RNA-seq, the background expressions of non-targeted cell types are not accounted for. Here we bridge this gap with an automated marker identification method that works for bulk RNA sequencing data. ResultsWe developed mastR, a novel computational tool for accurate marker identification from omics data. It leverages robust pipelines from edgeR and limma R/Bioconductor packages, performing pairwise comparisons between groups, and aggregating the results through rank-product-based permutation test. A signal-to-noise ratio approach is implemented to minimize background signals. We assess the performance of a mastR-derived NK cell signature against curated published signatures and find our derived signature performs as well if not better than published signatures. We also demonstrate the utility of mastR on simulated scRNA sequencing data and provide examples of mastR outperforming Seurat in marker selection. Availability and implementationAll statistical analyses were carried out using R (version 4.3.0 or higher) and Bioconductor (version 3.17 and higher). MastR is available as an R/Bioconductor package with a comprehensive vignette for ease of use (https://bioconductor.org/packages/release/bioc/html/mastR.html) and a guide hosted on GitHub: https://davislaboratory.github.io/mastR/.

bioinformatics↗

bioRxiv2024

hoodscanR: profiling single-cell neighborhoods in spatial transcriptomics data

Understanding complex cellular niches and neighborhoods have provided new insights into tissue biology. Thus, accurate neighborhood identification is crucial, yet existing methodologies often struggle to detect informative neighborhoods and generate cell-specific neighborhood profiles. To address these limitations, we developed hoodscanR, a Bioconductor package designed for neighborhood identification and downstream analyses using spatial data. Applying hoodscanR to breast and lung cancer datasets, we showcase its efficacy in conducting detailed neighborhood analyses and identify subtle transcriptional changes in tumor cells from different neighborhoods. Such analyses can help researchers gain valuable insights into disease mechanisms and potential therapeutic targets.

bioinformatics↗

bioRxiv2024

Trends of Plasmodium falciparum molecular markers associated with resistance to artemisinins and reduced susceptibility to lumefantrine in Mainland Tanzania from 2016 to 2021

BackgroundTherapeutic efficacy studies (TESs) and detection of molecular markers of drug resistance are recommended by the World Health Organization (WHO) to monitor the efficacy of artemis inin combination therapy (ACT). This study assessed the trends of molecular markers of artemis inin resistance and/or reduced susceptibility to lumefantrine using samples collected in TES conducted in Mainland Tanzania from 2016 to 2021. MethodsA total of 2,015 samples were collected during TES of artemether-lumefantrine at eight sentinel sites (in Kigoma, Mbeya, Morogoro, Mtwara, Mwanza, Pwani, Tabora, and Tanga regions) between 2016 and 2021. Photo-induced electron transfer polymerase chain reaction (PET-PCR) was used to confirm presence of malaria parasites before capillary sequencing, which targeted two genes: Plasmodium falciparum kelch 13 propeller domain (k13) and P. falciparum multidrug resistance 1 (pfmdr1). ResultsSequencing success was [≥]87.8%, and 1,724/1,769 (97.5%) k13 wild-type samples were detected. Thirty-seven (2.1%) samples had synonymous mutations and only eight (0.4%) had non-synonymous mutations in the k13 gene; seven of these were not validated by WHO as molecular markers of resistance (I416V, E433D, R471S, P475S, A578S, and Q613E). One sample from Morogoro in 2020 had a k13 R622I mutation, which is a validated marker of artemisinin partial resistance. For pfmdr1, all except two samples carried N86 (wild-type), while mutations at Y184F increased from 33.9% in 2016 to about 60.5% in 2021, and only four samples (0.2%) had D1246Y mutations. pfmdr1 haplotypes were reported in 1,711 samples, with 985 (57.6%) NYD, 720 (42.1%) NFD, and six (0.4%) carrying minor haplotypes (three with NYY, 0.2%; YFD in two, 0.1%; and NFY in one sample, 0.1%). Between 2016 and 2021, NYD decreased from 66.1% to 45.2%, while NFD increased from 38.5% to 54.7%. ConclusionThis is the first report of the R622I (k13 validated mutation) in Tanzania. N86 and D1246 were nearly fixed, while increases in Y184F mutations and NFD haplotype were observed between 2016 and 2021. Despite the reports of ART-R in Rwanda and Uganda, this study did not report any other validated mutations in these study sites in Tanzania apart from R622I suggesting that intensified surveillance is urgently needed to monitor trends of drug resistance markers and their impact on the performance of ACTs.

molecular biology↗

bioRxiv2024

Adenomatous polyposis coli (APC) regulates internalization and signaling of the chemorepellent receptor, Roundabout (ROBO) 1

The SLIT-ROBO signaling pathway regulates axon guidance and cell migration, and ROBO1 is a receptor for SLIT ligands. ROBO1 undergoes constitutive endocytosis which is enhanced upon SLIT2 binding, but the molecular mechanisms and functional consequences of this process are not well understood. Using pharmacologic inhibitors and molecular techniques, we found that clathrin-mediated endocytosis is necessary for SLIT2-induced inhibition of cell spreading. To explore the underlying mechanisms, we performed BioID to identify ROBO1-interacting proteins whose association with the cytoplasmic domain of ROBO1 is differentially regulated by SLIT2. We discovered that adenomatous polyposis coli (APC), a multifunctional tumor suppressor, constitutively interacts with ROBO1 but dissociates upon binding of SLIT2 and that this dissociation is necessary for clathrin-mediated endocytosis of ROBO1 and subsequent effects on cell morphology. These findings provide new insights into the functional mechanisms by which SLIT2 binding to ROBO1 effects changes in actin cytoskeletal architecture.

cell biology↗