Biology subjects

Jeon, J. H.

Publications and source records attributed to Jeon, J. H..

6 recordsLinked to original sources

bioRxiv2025

Novel DNA endonuclease activity of human ERK1 protein

ERK1 is a key kinase in the mitogen-activated protein kinase pathway, which transduces extracellular signals into cellular responses. Following triggering of the pathway, cytosolic ERK1 is phosphorylated, translocates into the nucleus, and activates DNA-bound transcription factors and target genes. This study reports a novel, non-canonical role of human ERK1 as a DNA endonuclease. It catalyzes single-strand DNA breaks in sequence-unspecific yet, topology-sensitive manners. ERK1 catalysis requires magnesium ions and no ATP consumption. Comprehensive biochemical and in silico structural analyses indicate that a Mg2+ pocket, including a residue N171, which is allosterically modulated by the N-terminal domain, is important for DNA substrate binding and catalysis. Fluorescence imaging analysis suggests that ERK1 may interact with cytoplasmic DNAs in molecular condensates and destabilize them. Collectively, this study reveals an unprecedented role of ERK1 in nicking DNA molecules, which highlights the potential to regulate the fate of cytoplasmic DNAs.

molecular biology↗

bioRxiv2024

Selection, Design and Immunogenicity Studies of ASFV Antigens for Subunit mRNA Cocktail Vaccines with Specific Immune Response Profiles

Development of safe and effective subunit vaccines for controlling African Swine Fever Virus (ASFV) infection has been hampered by a lack of protective viral antigens, complex virion structures, and multiple mechanisms of infection. Here, we selected ASFV antigens based on their localization on the virion, known functions, and homologies to the subunits of the protective vaccinia virus vaccine. We also engineered viral capsid proteins for inducing optimal antibody responses and designed T cell-directed antigen for inducing broad and robust cellular immunity. The selected antigens in lipid nanoparticle-mRNA formulations were evaluated for immunogenicity in both mice and pigs with concordant results. Different antigens induced divergent immune response profiles, including the levels of IgG and T cell responses and effector functions of anti-sera. We further developed a computational approach to combine antigens into cocktails for inducing specific immune response profiles and validated candidate cocktail vaccines in mice. Our results provide a basis for further evaluating candidate subunit mRNA vaccines in challenge studies. TeaserNovel strategies to develop subunit vaccines for ASFV and other complex large DNA viruses.

immunology↗

bioRxiv2024

Membrane Expression Enhances Folding, Multimeric Structure Formation, and Immunogenicity of Viral Capsid Proteins

Viral capsid proteins are widely explored for subunit vaccine development but are often hampered by their complexity of production and low immunogenicity. Here, we report a simple approach to overcome these challenges by combining mRNA vaccine technology with protein engineering. Using African swine fever virus (ASFV) capsid proteins P72 and penton as models, we engineered them into membrane-bound and secreted forms, and compared their immunogenicity to the native intracellular form in mice and pigs through mRNA vaccination. The membrane-bound and secreted P72 and penton folded into their native multimeric structure independent of viral chaperone, therefore preserving their conformational epitopes. The membrane-bound P72 and penton also elicited significantly stronger antibody and T cell responses than their secreted or intracellular counterparts. Our study provides a simple approach to enhance folding, multimeric structure formation, and immunogenicity of viral capsid proteins for ASFV subunit vaccine development and immunogenicity of intracellular proteins in general.

immunology↗

bioRxiv2024

Identification of the drug/metabolite transporter 1 as a marker of quinine resistance in a NF54xCam3.II P. falciparum genetic cross.

The genetic basis of Plasmodium falciparum resistance to quinine (QN), a drug used to treat severe malaria, has long been enigmatic. To gain further insight, we used FRG-NOD human liver-chimeric mice to conduct a P. falciparum genetic cross between QN-resistant (Cam3.II) and QN-sensitive (NF54) parasites, which also differ in their susceptibility to chloroquine (CQ). By applying different selective conditions to progeny pools prior to cloning, we recovered 120 unique recombinant progeny. Drug profiling and quantitative trait loci analyses of the progeny revealed predominant peaks on chromosomes 7 and 12 associated with CQ and QN resistance, that is consistent with a multifactorial mechanism of resistance for these compounds. CQ and monodesethyl-CQ (md-CQ) resistance mapped to a chromosome 7 region harboring pfcrt as expected. However, for QN, resistance mapped to a dominant chromosome 7 peak centered 295 kb downstream of pfcrt, with pfcrt showing a smaller peak. We identified the drug/metabolite transporter 1 (DMT1) as the top chromosome 7 candidate due to its structural similarity to PfCRT and proximity to the peak. Deleting DMT1 in QN-resistant Cam3.II parasites significantly sensitized the parasite to QN but not to the other drugs tested, suggesting that DMT1 mediates QN response specifically. We localized DMT1 to structures associated with vesicular trafficking, as well as the parasitophorous vacuolar membrane, lipid bodies, and the digestive vacuole. We also observed that mutant DMT1 transports more QN than the wild-type isoform in vitro. Gene editing confirmed an additional role for mutant PfCRT in mediating QN resistance. In addition, we identified an ATP-dependent zinc metalloprotease (FtsH1) as one of the top candidates in the chromosome 12 locus and confirmed its role as a potential mediator of QN resistance and a modulator of md-CQ resistance using CRISPR/Cas9 SNP-edited lines. Interestingly, this chromosome 12 region mapped to resistance to both CQ and QN and was preferentially co-inherited with pfcrt. Our study demonstrates that DMT1 is a novel marker of QN resistance and that a new chromosome 12 locus associates with CQ and QN response, with ftsh1 as a potential candidate, suggesting these genes in addition to pfcrt should be genotyped in surveillance and clinical settings.

genetics↗

bioRxiv2019

Acute characterization of tissue and functional deficits in a clinically translatable pig model of ischemic stroke

The acute stroke phase is a critical time frame used to evaluate stroke severity, therapeutic options, and prognosis while also serving as a major target for the development of diagnostics. To better understand stroke pathophysiology and to enhance the development of treatments, our group developed a translational pig ischemic stroke model. In this study, the evolution of acute ischemic stroke tissue damage, immune response, and functional deficits were further characterized in the pig model. Stroke was induced by middle cerebral artery occlusion in Landrace pigs. At 24 hours post-stroke, magnetic resonance imaging revealed a decrease in ipsilateral diffusivity and an increase in hemispheric swelling and intracranial hemorrhage resulting in notable midline shift. Stroke negatively impacted white matter integrity leading to decreased fractional anisotropy. Similar to acute clinical patients, stroked pigs showed a reduction in circulating lymphocytes and a surge in neutrophils and band cells. Functional responses corresponded with structural changes with reduced exploration in open field testing and impairments in spatiotemporal gait parameters. This novel, acute ischemia characterization provides important insights into tissue and functional level changes in a pig model that can be used to identify treatment targets and future testing of therapeutics and diagnostics.

neuroscience↗

bioRxiv2019

Dual activity of PNGM-1, a metallo-β-lactamase and tRNase Z, pinpoints the evolutionary origin of subclass B3 metallo-β-lactamases

Antibiotic resistance is a steadily increasing global problem which could lead to a fundamental upheaval in clinical care with the potential to return us to the pre-antibiotic era1-4. The production of {beta}-lactamases, a group of enzymes that confer antibiotic resistance in Gram-negative bacteria, is now one of the major barriers in treating Gram-negative infections5. {beta}-Lactamases are classified according to their catalytic mechanisms into serine {beta}-lactamases and metallo-{beta}-lactamases6,7. There are functional and structural similarities between serine {beta}-lactamases and penicillin-binding proteins, and so serine {beta}-lactamases are thought to have evolved from a penicillin-binding protein7,8. Given the functional and structural differences between serine {beta}-lactamases and metallo-{beta}-lactamases, metallo-{beta}-lactamases are thought to have evolved from a protein other than a penicillin-binding protein, but to date this ancestor remains unknown8-11. We discovered PNGM-1, the first subclass B3 metallo-{beta}-lactamase, in deep-sea sediments that predate the antibiotic era12. Here we discover the dual activity of PNGM-1, pinpointing the evolutionary origin of subclass B3 metallo-{beta}-lactamases. Phylogenetic analysis suggested that PNGM-1 could yield insights into the evolutionary origin of subclass B3 metallo-{beta}-lactamases. We reveal the structural similarities between tRNase Zs and PNGM-1, which prompted us to investigate their evolutionary relationship and the possibility of them possessing dual enzymatic activities. We demonstrate that PNGM-1 has dual activity with both true metallo-{beta}-lactamase and tRNase Z activity, suggesting that PNGM-1 is thought to have evolved from a tRNase Z. We also show kinetic and structural comparisons between PNGM-1 and other proteins including subclass B3 metallo-{beta}-lactamases and tRNase Zs. These comparisons revealed that the B3 metallo-{beta}-lactamase activity of PNGM-1 is a promiscuous activity and subclass B3 metallo-{beta}-lactamases are thought to have evolved through PNGM-1 activity. Our work provides a foundation for the evolution of tRNase Z into subclass B3 metallo-{beta}-lactamases through the dual activity of PNGM-1.

microbiology↗