Biology subjects

Ankarklev, J.

Publications and source records attributed to Ankarklev, J..

9 recordsLinked to original sources

bioRxiv2025

Deep Integrated Network Analysis: a data-driven tool to discover and characterize disease pathways in the liver

Background & AimsAn extensive number of studies have utilized transcriptomic profiling as a valuable tool for uncovering genes related to diseases and physiological processes of the liver. Here we combine this wealth of information to provide a powerful resource, by computationally constructing a comprehensive and unbiased network of gene interactions specific to the liver. MethodsWe have performed a computational approach termed Deep Integrated Network Analysis (DINA) on a curated catalog of 655 liver transcriptomic datasets (including a total of 48,311 transcriptomes). These datasets include human, monkey, mouse, rat and other mammalian species, and studies linked to a broad range of conditions. Together this facilitated construction of a network of strongly conserved gene-gene interactions relevant across the spectrum of liver diseases. ResultsThe Liver DINA Resource described herein contains 89,683 statistically conserved interactions among 19,317 genes in a unified network unique to the mammalian liver. The network unveils a hierarchical structure of strongly co-regulated modules, which are organized into a Tree-and-Leaf Network to provide a comprehensive overview of the resource. ConclusionsThis data-driven resource provides an interactive, publicly available tool for the examination of previously undescribed gene networks, and enables unbiased analysis of transcriptomic datasets of the liver, thus preventing bias in favor of well-studied genes and pathways and providing a complementary approach towards novel discoveries.

systems biology↗

bioRxiv2025

Genome-wide profiling of tRNA modifications reveal the presence of divergent signatures in Plasmodium falciparum

tRNAs are known to be extensively decorated with various nucleotide modifications, which can modulate the biological properties of tRNAs, such as promoting translation efficiency or fidelity, influencing codon preference and stabilizing tertiary structure of tRNAs. Dynamic alteration of the tRNA modifications, particularly under stress, are conserved gene regulatory mechanisms employed by cells across the kingdoms of life. The malaria-causing Plasmodium falciparum, which has a highly AT-biased genome, is reliant on a non-redundant set of tRNA genes to decode distinct and codon-skewed transcriptomes across its developmental stages. This genomic feature highlights the regulatory potential of tRNA modifications and warrants studies on how the tRNA epitranscriptome can impact gene regulatory function in this parasite. However, systematic studies of tRNA modifications in P. falciparum remain sporadic. In this study, we present a sequencing-based analysis of tRNA modifications in P. falciparum through optimizing the TGIRT-tRNA sequencing approach. The optimized protocol significantly reduces reverse transcription (RT) stop-induced short reads and enhances full-length cDNA synthesis, enabling the identification and stoichiometric estimation of a select nucleotide modifications at single-base resolution. We were able to identify seven types of conserved tRNA modifications and discovered two non-canonical signatures at A59 and U73 positions on specific nuclear-encoded tRNAs, which provides new insights into previously unreported modification sites. Our findings further reveal the dynamic nature of tRNA modifications during stage progression and under stress conditions.

microbiology↗

bioRxiv2023

Host-Pathogen Interactions in the Plasmodium-Infected Mouse Liver at Spatial and Single-Cell Resolution

Upon infecting its vertebrate host, the malaria parasite initially invades the liver where it undergoes massive replication, whilst remaining clinically silent. The spatial coordination of factors regulating immune responses and metabolic zonation during malaria infection, in the true tissue context, remains unexplored. Here, we perform spatial transcriptomics in combination with single-nuclei RNA-sequencing (snRNA-seq) over multiple time points during liver infection to delineate transcriptional programs of host-pathogen interactions across P. berghei-infected liver tissues. Our data suggest changes in gene expression related to lipid metabolism in response to Plasmodium infection in the proximity of infected hepatocytes, such as the modulation of the expression of genes involved in peroxisome proliferator-activated receptor pathway signaling. The data further indicate the presence of inflammatory hotspots with distinct cell type compositions and differential liver inflammation programs along the lobular axis in the malaria-infected tissues. Furthermore, a significant upregulation of genes involved in inflammation is observed in liver tissues of control mice injected with mosquito salivary gland components, which is considerably delayed compared to P. berghei infected mice. Our study establishes a benchmark for investigating transcriptome changes during host-parasite interactions in tissues, it provides informative insights regarding in vivo study design linked to infection, and provides a useful tool for the discovery and validation of de novo intervention strategies aimed at malaria liver stage infection.

molecular biology↗

bioRxiv2023

Single-cell sequencing of tumor-associated macrophages in a Drosophila model.

IntroductionTumor-associated macrophages may act to either limit or promote tumor growth, yet the molecular basis for either path is poorly characterized. MethodsWe use a larval Drosophila model that expresses a dominant-active version of the Rasoncogene (RasV12) to study dysplastic growth during early tumor progression. We performed single-cell RNA-sequencing of macrophage-like hemocytes to characterize these cells in tumor-compared to wild type larvae. Hemocytes included manually extracted tumor-associated-as well as circulating cells. Results and discussionWe identified 5 distinct hemocyte clusters. In addition to RasV12 larvae we included a tumor model where the activation of effector caspases was inhibited, mimicking an apoptosis-resistant setting. Circulating hemocytes from both tumor models differ qualitatively from control wild-type cells - they display an enrichment for genes involved in cell division, which was confirmed using proliferation assays. Split analysis of the tumor models further reveals that proliferation is strongest in the caspase-deficient setting. Similarly, depending on the tumor model, hemocytes that attach to tumors activate different sets of immune effectors - antimicrobial peptides dominate the response against the tumor alone, while caspase inhibition induces a shift toward members of proteolytic cascades. Finally, we provide evidence for transcript transfer between hemocytes and possibly other tissues. Taken together, our data support the usefulness of Drosophila to study the response against tumors at the organismic level.

cancer biology↗

bioRxiv2023

scDual-Seq of Toxoplasma gondii-infected mouse bone marrow-derived dendritic cells reveals host cell heterogeneity and differential infection dynamics

Host-parasite interactions include complex interplays between an invading and a defending organism, each continuously adapting to gain the upper hand. The protozoan parasite, Toxoplasma gondii, can invade every nucleated cell type in a vertebrate host, including immune cells while the host mounts a protective response. Here, we utilize Dual-scSeq to parse out heterogeneous transcription of bone marrow-derived dendritic cells (BMDCs) infected with T. gondii type I, RH (LDM) or type II, ME49 (PTG) parasites, over multiple time points post infection. We find that the two parasite lineages distinctly manipulate two subpopulations of infected BMDCs. Co-expression networks establish host and parasite genes, with implications for modulation of host immunity and host-pathogen interactions. Integration of published data validates immune pathways and suggests novel candidate genes involved in host-pathogen interactions. This study aims to provide a comprehensive resource for future characterization of host-pathogen interplay among other protozoan parasites within their host niches, as well as that of bacterial and viral pathogens.

microbiology↗

bioRxiv2022

Single-cell transcriptomics to define Plasmodium falciparum stage-transition in the mosquito midgut

Malaria inflicts the highest rate of morbidity and mortality among the vector-borne diseases. The dramatic bottleneck of parasite numbers that occurs in the gut of the obligatory vector mosquito provides a promising target for novel control strategies. Using single-cell transcriptomics, we analyzed Plasmodium falciparum development in the mosquito gut, from unfertilized female gametes through the first 20 hours post blood feeding, including the zygote and ookinete stages. This study revealed the transcriptional trajectories of the ApiAP2 family of transcription factors, and of parasite stress genes in response to the harsh environment of the mosquito midgut. Further, employing structure-based functional predictions we found several upregulated genes predicted to encode intrinsically disordered proteins (IDPs), a category of proteins known for their importance in regulation of transcription, translation and protein-protein interactions. IDPs are known for their antigenic properties and may serve as suitable targets for antibody or peptide-based transmission suppression strategies.

microbiology↗

bioRxiv2021

Spatial Transcriptomics to define transcriptional patterns of zonation and structural components in the liver

Reconstruction of heterogeneity through single-cell transcriptional profiling has greatly advanced our understanding of the spatial liver transcriptome in recent years. However, global transcriptional differences across lobular units remain elusive in physical space. Here, we implement Spatial Transcriptomics to perform transcriptomic analysis across sectioned liver tissue. We confirm that the heterogeneity in this complex tissue is predominantly determined by lobular zonation. By introducing novel computational approaches, we enable transcriptional gradient measurements between tissue structures, including several lobules in a variety of orientations. Further, our data suggests the presence of previously transcriptionally uncharacterized structures within liver tissue, contributing to the overall spatial heterogeneity of the organ. This study demonstrates how comprehensive spatial transcriptomic technologies can be used to delineate extensive spatial gene expression patterns in the liver, indicating its future impact for studies of liver function, development and regeneration as well as its potential in pre-clinical and clinical pathology.

genomics↗

bioRxiv2019

A histone methyltransferase inhibitor can reverse epigenetically acquired drug resistance in the malaria parasite Plasmodium falciparum

Malaria parasites invade and replicate within red blood cells (RBCs), extensively modifying their structure and gaining access to the extracellular environment by placing the plasmodial surface anion channel (PSAC) into the RBC membrane. Expression of members of the cytoadherence linked antigen gene 3 (clag3) family is required for PSAC activity, a process that is regulated epigenetically. PSAC is a well-established route of uptake for large, hydrophilic antimalarial compounds and parasites can acquire resistance by silencing clag3 gene expression, thereby reducing drug uptake. We found that exposure to sub-IC50 concentrations of the histone methyltransferase inhibitor chaetocin caused substantial changes in both clag3 gene expression and RBC permeability, reversing acquired resistance to the antimalarial compound blasticidin S that is transported through PSAC. Chaetocin treatment also altered progression of parasites through their replicative cycle, presumably by changing their ability to modify chromatin appropriately to enable DNA replication. These results indicate that targeting histone modifiers could represent a novel tool for reversing epigenetically acquired drug resistance in P. falciparum.\n\nImportanceDrug resistance is a major concern for the treatment of infectious diseases throughout the world. For malaria, a novel mechanism of resistance was recently described in which epigenetic modifications led to a resistance phenotype that is rapidly reversible, thus reducing the fitness cost that is often associated with genetic mutations that lead to resistance. The possibility of this type of resistance arising in a natural setting is particularly troubling since parasites could rapidly switch to and from a resistant phenotype, thus making it especially difficult to combat. Here we show that application of a histone methyltransferase inhibitor can rapidly reverse the epigenetic changes that lead to drug resistance, thereby causing parasites to revert to a drug sensitive phenotype. This is a novel application of drugs that target epigenetic modifiers and lends additional support for ongoing efforts to develop drugs against malaria that target the histone modifiers of the parasite.

microbiology↗

bioRxiv2018

Generation of Transgenic Human Malaria Parasites With Strong Fluorescence in the Transmission Stages

Malaria parasites have a complex life cycle that includes specialized stages for transmission between their mosquito and human hosts. These stages are an understudied part of the lifecycle yet targeting them is an essential component of the effort to shrink the malaria map. The human parasite Plasmodium falciparum is responsible for the majority of deaths due to malaria. Our goal was to generate transgenic P. falciparum lines that could complete the lifecycle and produce fluorescent transmission stages for more in-depth and high-throughput studies. Using zinc-finger nuclease technology to engineer a marker-free integration site, we generated three transgenic P. falciparum lines in which tdtomato or gfp were stably integrated into the genome. Expression was driven by either stage-specific peg4 and csp promoters or the constitutive ef1a promoter. Phenotypic characterization of these lines demonstrates that they complete the life cycle with high infection rates and give rise to fluorescent mosquito stages. The transmission stages are sufficiently bright for intra-vital imaging, flow cytometry and scalable screening of chemical inhibitors and potentially inhibitory antibodies.

microbiology↗