Biology subjects

Jang, S.

Publications and source records attributed to Jang, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Senescent cells induce vascular MHC II to recruit CD4+ T cells and drive inflammation in aging adipose tissue

Adipose tissue exhibits pronounced inflammation during aging, yet the mechanisms sustaining this chronic state are not well understood. By creating an atlas integrating histology, single-nucleus transcriptomics and flow cytometry across the murine lifespan, we find that age-associated inflammation is distinct from the obesity-like inflammatory profile observed at mid-life. Specifically, age-associated inflammation is characterized by a potent interferon-gamma (IFN{gamma}) response signature and the accumulation of T cells. We demonstrate that senescent cells act as an upstream trigger, indirectly initiating an IFN{gamma} response that upregulates vascular MHC II to promote extravasation of CD4+ T cells into the aging tissue. These recruited T cells then act as a critical source of IFN{gamma}, thereby perpetuating a positive feedback loop that maintains chronic immune infiltration and tissue inflammation. These results provide a multi-modal view of adipose aging and identify a mechanism that sustains its age-associated inflammation.

immunology↗

bioRxiv2026

A novel anti-climbing barrier prevents black soldier fly larval escape from rearing containers

The mass-rearing of black soldier fly (Hermetia illucens) larvae (BSFL) is a promising solution for converting organic waste into high-quality insect protein, but preventing larval escape from open-top rearing containers remains a major management challenge. Conventional escape-control methods are often unreliable or impractical. To address this, we developed and evaluated a novel physical barrier, the anti-climbing tape, featuring regularly arranged macroscale protrusions designed to disrupt larval locomotion on vertical surfaces. We conducted a series of experiments to examine the design parameters of the anti-climbing tapes, including the gap size between protrusions and the number of protrusion rows. Our results demonstrate that the anti-climbing tape prevents escape via a dual mechanism: (1) physical obstruction, in which gaps narrower than the larval body width block larvae from passing through, and (2) adhesion reduction, in which the elevated protrusion array decreases the effective contact area for wet adhesion while increasing gravitational torque acting on the larval body. The effectiveness of these mechanisms was dependent on larval size. A design featuring 0.5-mm gaps and a 15-row protrusion array completely prevented the escape of later-instar larvae (>10 mm) in a 20-day large-scale trial, whereas the method was less effective for smaller larvae. In conclusion, the anti-climbing tape provides a robust and chemical-free approach to BSFL escape in mass rearing. To ensure reliable performance, its design parameters, both gap size and array width must be optimised to suppress the mechanical and adhesive components of larval climbing according to the target larval size. Conflict of interestS. Jang and M. Shimoda are inventors on a Japanese patent application (No. 2022-172252, filed November 27, 2022) related to the method described in this manuscript. FundingThis study was supported by Korea-Japan Joint Government Scholarship Program for the Students in Science and Engineering Departments, the Korean Scholarship Foundation, and the University of Tokyo Foundations Support Fund for International Students.

bioengineering↗

bioRxiv2026

Cellular Chemical Dynamics Governing Signal Transduction and Adaptive Gene Expression: Beyond Classical Kinetics

Cellular adaptation is inherently nonstationary processes with complex stochastic dynamics1-5. Despite remarkable progress in quantitative biology6-11, a quantitative understanding of the cell adaptation dynamics in terms of the underlying cellular network remains elusive. Here, we present the next-generation chemical dynamics model and theory for cellular networks, providing an effective, quantitative description of the adaptive gene expression dynamics in living cells responding to external stimuli. Unlike conventional kinetics, chemical dynamics of cellular network modules are characterized by their reaction-time distributions, rather than by rate coefficients12. For a general model of cell signal transduction and adaptive gene expression, we derive exact analytical expressions for the time-dependent mean and variance of protein numbers produced in response to external stimuli, validated by accurate stochastic simulations. These results provide a unified, quantitative explanation of the stochastic responses of diverse E. coli genes to antibiotic stress and transcriptional induction. Our analysis reveals existence of a general quadratic relationship between the mean and variance of activation times across diverse genes. The gene activation process influences transient dynamics of downstream protein levels, but not their steady-state levels. In contrast, post-translational maturation process affects both transient dynamics and steady-state variability of mature protein levels. This finding indicates that the gene expression variability measured by fluorescent reporter proteins depends on the maturation time of the reporters. This work suggests a new direction for the development of digital twins of living cells.

biophysics↗

bioRxiv2025

PKMYT1 inhibition induces DNA damage and synergizes with immune checkpoint blockade in CCNE1-amplified gastroesophageal adenocarcinoma

PurposeCCNE1 amplification, found in approximately 10% of gastroesophageal adenocarcinoma (GEA), drives chromosomal instability and is associated with an immune-cold tumor microenvironment. Recent studies suggest that PKMYT1 inhibition is synthetic lethal in CCNE1-amplified cancers; however, its role in GEA is largely uncharacterized. We investigated the therapeutic activity of PKMYT1 inhibition in CCNE1-amplified GEA and its potential combination with immunotherapy. Experimental DesignWe evaluated lunresertib (RP-6306), a selective first-in-class PKMYT1 inhibitor, in CCNE1-amplified and wild-type GEA cell lines to define its effects on cell viability, DNA damage, and gene expression changes. To investigate the role of PKMYT1 blockade on immune microenvironment modulation, we used a syngeneic murine model of CCNE1;Trp53-/- GEA xenografts treated with lunresertib, anti-PD-1, or the combination. ResultsLunresertib was selectively cytotoxic in CCNE1-amplified GEA cell lines in cell viability and clonogenic assays. Mechanistically, treatment with lunresertib induced DNA damage, evidence by increased {gamma}H2AX expression and DNA micronuclei formation, and activated pro-inflammatory signaling pathways by gene set enrichment analysis. In a CCNE1-amplified GEA murine model, PKMYT1 inhibition promoted T cell infiltration, reduced myeloid cells, and synergized with anti-PD-1 therapy to induce tumor regression. ConclusionsOur results suggest that CCNE1 amplification is a potentially actionable target in GEA and support the development of combination therapeutic strategies utilizing PKMYT1 inhibition and PD-1 blockade. Translational RelevanceGastroesophageal adenocarcinoma (GEA) is an aggressive malignancy with poor prognosis and few actionable molecular alterations. CCNE1 amplification is present in approximately 10% of patients with GEA and represents a potential therapeutic vulnerability through synthetic lethality with PKMYT1 inhibition. We demonstrate that targeting CCNE1-amplified GEA through PKMYT1 inhibition with lunresertib is selectively cytotoxic, induces DNA damage, and activates inflammatory signaling pathways. In a syngeneic murine model of CCNE1-amplified gastric cancer, we further identified that PKMYT1 inhibition induced T cell infiltration and tumor microenvironment remodeling, and synergized with anti-PD-1 therapy to drive tumor regression. Together, these results support further development of PKMYT1 inhibition in combination with PD-1 blockade for CCNE1-amplified GEA.

cancer biology↗

bioRxiv2025

Saxiphilin functions as a "toxin sponge" protein that counteracts the effects of saxitoxin poisoning

Saxitoxin (STX) is among the most potent toxins known, is classified as a chemical weapon, and is the archetype of the paralytic shellfish toxin (PST) family produced by marine and freshwater harmful algal blooms (HAB)1-3. STX causes paralysis and death through inhibition of voltage-gated sodium channels (NaVs), has no antidote, and poses a public health and commercial fishing threat due to its accumulation in seafood and increasing HAB occurrences1,4. Although STX is lethal to varied vertebrates5-7, including humans4,8,9, certain frogs resist STX poisoning6,7. This phenotype is thought to depend on soluble toxin sponge high-affinity STX binding proteins (saxiphilins, Sxphs)6,7,10,11 that provide resistance through a competition mechanism different from classic target site ion channel mutation mechanisms12-14. Here, we test this idea directly and show that a single dose of American bullfrog (Rana catesbeiana) Sxph (RcSxph) is sufficient to counteract STX neurotoxicity and lethality in mice using paradigms where STX and Sxph are administered together or sequentially in either order. Importantly, this function requires the RcSxph high-affinity STX binding site. Our findings provide in vivo validation that Sxphs are toxin sponges that protect against STX poisoning and highlight the potential to harness this protein class as antidotes for PSTs and other toxins.

pharmacology and toxicology↗

bioRxiv2025

Soil pH as an external filter shaping insect-microbe gut symbiosis

BackgroundMany animals and plants establish intimate symbiotic relationships with specific microorganisms acquired from the environment. Given the immense diversity of environmental microbiomes, selecting appropriate partners from such a vast microbial pool poses a critical challenge for host organisms. To meet this challenge, hosts have evolved sophisticated internal partner-choice mechanisms that ensure stable associations with beneficial microbes. However, because these symbionts primarily inhabit external environments, environmental conditions themselves are also expected to play pivotal roles in the establishment of symbiosis. Despite this expectation, the mechanistic role of external environmental filters in shaping the intended symbiosis remains largely unexplored. Focusing on stink bugs, which acquire their symbiotic bacteria from soil each generation, we investigated how soil properties influence the establishment of gut symbiosis in terrestrial insects. ResultsMicrobiome analyses confirmed that Burkholderia sensu lato overwhelmingly dominates a specific gut organ in six stink bug species from the superfamilies Coreoidea and Lygaeoidea, including serious agricultural pests (relative abundance ranging from 74.5% to 100%). Rearing experiments with isolated Burkholderia revealed that insects were strictly dependent on this symbiont; failure to acquire it from soil severely reduced host growth and reproduction, indicating that the availability of symbionts from soil represents an ecological bottleneck. Field surveys identified patches of exceptionally high stink bug density in weedy fields with soil pH <7.0, whereas such aggregations were absent in fields with pH [≥]7.0. Laboratory experiments with collected field soils showed that the abundance of Burkholderia in soils was negatively correlated with soil pH, and stink bugs readily acquired their symbionts from soils with pH <7.0 but rarely from soils with pH [≥]7.0. Experimental manipulations of soil pH followed by rearing experiments confirmed that increasing soil pH to 7-8 markedly suppressed symbiont acquisition by the host, likely by impairing symbiont growth and motility. ConclusionsWe demonstrate that, beyond host-intrinsic mechanisms, a soil chemical property externally filters symbiotic bacteria prior to colonization inside the host. These findings reveal that, alongside host physiology, environmental conditions--mediated through the soil and host gut microbiomes--shape the assembly, maintenance, and evolution of host-microbe symbiotic associations.

microbiology↗

bioRxiv2025

Receptor-tethered orthogonal IL-2 enhances regulatory T cell therapy

Regulatory T cell (Treg) therapy is an emerging platform for controlling immune overactivation. Efficacy of Treg therapy is limited by the poor persistence of infused Tregs due to insufficient IL-2, which is essential for Treg survival and function. IL-2 activates many immune cells besides Tregs, imposing a challenge for the selective provision of IL-2 to infused Tregs. In this study, we found infusions of orthogonal (ortho) IL-2 failed to enhance Tregs engineered with a corresponding orthoIL-2 receptor (IL-2R) in a mouse model of autoimmune diabetes. We then developed a receptor-tethered orthoIL-2 by optimizing the combination of IL-2, IL-2R, and the linker connecting them to achieve autocrine signaling selectively in engineered Tregs. Tregs expressing the tethered orthoIL-2 showed autocrine IL-2 signaling in vitro, enhanced CD25, CTLA-4, and Foxp3 expression, persisted without exogenous IL-2 in vivo, and prevented autoimmune diabetes using as few as 2,000 Tregs. Knocking the tethered orthoIL-2 construct into the Foxp3 locus enabled Treg-specific expression, with the additional benefit of positively reinforcing tethered orthoIL-2 expression through the activation of the Foxp3 gene by enhanced IL-2 signaling. Together, these results illustrate a safe and effective cell-engineering solution for overcoming Tregs dependency on exogenous IL-2, thereby achieving superior therapeutic efficacy.

immunology↗

bioRxiv2025

Fast, Bright and Reversible Rhodamine Tags for Live-Cell Imaging

We present Rho-tag and SiR-tag, engineered protein tags derived from bacterial multidrug-resistance proteins that bind unsubstituted (silicon-) rhodamines with nanomolar affinity, enabling fast, reversible, and fluorogenic protein labeling. In live cells, Rho-tag labeling occurs within seconds -- faster than HaloTag7 -- and the tags are compatible with super-resolution methods like STED, SMLM, and MINFLUX. The high specificity of Rho-tag and SiR-tag for unsubstituted rhodamines allows their use alongside HaloTag7 and SNAP-tag. In vivo applications are demonstrated by efficient neuronal labeling in zebrafish larvae.

bioengineering↗

bioRxiv2025

Structural basis of liver de-targeting and neuronal tropism of CNS-targeted AAV capsids

Crossing the blood-brain barrier while minimizing liver transduction is a key challenge in developing safe adeno-associated virus (AAV) vectors for treating brain disorders. In mice, the engineered capsid PHP.eB shows enhanced brain transduction, while the further engineered CAP-B10 is also de-targeted from astrocytes and liver. Here, we solve cryo-EM structures of CAP-B10 and its complex with AAV receptor (AAVR) domain PKD2, at 2.22 and 2.20 [A] resolutions, respectively. These structures reveal a structural motif that hinders AAVR binding, which we confirm by measuring affinities. We show that this motif is transferable to other capsids by solving cryo-EM structures of AAV9-X1 and AAV9-X1.1, without and with PKD2, at 3.09, 2.51, and 2.18 [A], respectively. Using this structural information, we designed and validated novel AAV variants with reduced liver and altered brain cell tropism in vivo. Overall, our findings demonstrate that rationally modulating AAVR affinity can alter liver targeting and cellular tropism.

molecular biology↗

bioRxiv2025

AAVs Targeting Human Carbonic Anhydrase IV Enhance Gene Delivery to the Brain

Clinically approved gene therapies based on natural adeno-associated virus (AAV) serotypes have restricted applications, particularly in the brain, due to their poor targeting, high dose requirements, and resulting safety concerns. Directed evolution of enhanced AAV capsids in mice or non-human primates (NHPs) has resulted in markedly improved performance in those species, but inter-species differences present a serious challenge for translating these vectors into human therapies. Here, we engineer AAVs to target human carbonic anhydrase IV (CA-IV), a recently identified blood-brain barrier (BBB) transcytosis receptor. Among known transcytosis receptors, CA-IV is notable for its relatively specific expression in brain endothelial cells and the potency of AAVs that target it in mice. CA-IVs AAV binding site, and thus the mouse vectors enhanced brain potency, is not conserved across species, so we employed a two-phase engineering strategy to identify AAVs optimized for human CA-IV-dependent gene delivery to the brain. We first used in vitro receptor-based selection of a vast AAV library to exclude capsids that do not bind human CA-IV, followed by in vivo selection in "humanized" mice expressing human CA-IV in brain endothelial cells. Notably, we find that human CA-IV binding capsid variants that were poorly enriched in the pull-down selection outperform strong binders in vivo. The most promising vector, AAV-hCA4-IV77, engages human CA-IV to achieve 100-fold greater brain transduction than AAV9, with robust neuronal and astrocytic coverage throughout multiple brain regions. These results advance our understanding of receptor-targeted capsid design and support the therapeutic potential of human CA-IV-engaging AAVs.

bioengineering↗

bioRxiv2025

CD11c+ CD8 T cells cause IFN-g-dependent autoimmune neuroinflammation that is restrained by PD-1 signaling.

In multiple sclerosis (MS) lesions, CD8 T cells outnumber CD4 T cells, suggesting that they contribute to MS pathology. However, little is known on the role of CD8 T cells in MS, partially due to the nearly ubiquitous use of experimental autoimmune encephalomyelitis (EAE) models that are mediated by CD4 T cells, with no CD8 T cell contribution. Importantly, MS and EAE differ in both their distribution of CNS lesions and their symptoms, indicating differences in CNS inflammation. MS lesions are more prevalent in the brain, while EAE lesions are more frequent in the spinal cord. Additionally, neurologic deficits in MS rarely parallel the paralysis typical for CD4 T cell-mediated EAE (CD4-EAE). In contrast, CD8-EAE models suggest that CD8 T cells preferentially cause brain inflammation, but little is known regarding how brain and spinal cord inflammation may differ, and how CD8 T cells may contribute to those differences. We have established an adoptive CD8-EAE mouse model characterized by brain-centered inflammation, severe ataxia, and weight loss. CNS inflammation in the brain and spinal cord differed in immune cell numbers, cellular composition, and inflammatory signatures. CD8-EAE could be suppressed by blocking IFN-{gamma}, and exacerbated by blocking PD-1, with concomitant changes in numbers of CNS-infiltrating monocytes. Most CD8 T cells in the CNS were CD11c+, suggesting that they are the pathogenic subset. We describe a robust CD8-EAE model, identify differences between brain and spinal cord inflammation, and characterize mechanisms that control CD8 T cell-mediated neuroinflammation, thereby furthering understanding of these cells in EAE/MS. Brief SummaryCD8 T cells are understudied in MS due to a lack of suitable animal models. We developed a CD8 T cell dependent model of MS.

immunology↗

bioRxiv2025

CPSF6 Promotes HIV-1 Preintegration Complex Function

Cleavage and polyadenylation specificity factor 6 (CPSF6) is part of the cellular cleavage factor I mammalian (CFIm) complex that regulates mRNA processing and polyadenylation. CPSF6 also functions as a HIV-1 capsid (CA) binding host factor and promotes viral DNA integration targeting into gene dense regions of the host genome. However, the effects of CPSF6 on the activity of the HIV-1 preintegration complex (PIC) - the machinery that carries out viral DNA integration to establish infection - is unknown. To study CPSF6s role in HIV-1 PIC function, we extracted PICs from cells depleted of CPSF6 or expressing a CPSF6 mutant that cannot bind to CA. These PICs exhibited significantly lower integration activity when compared to the control PICs. Addition of recombinant CPSF6 restored the integration activity of PICs extracted from the mutant cells, suggesting a direct role of CPSF6 in PIC function. To solidify CPSF6s effect on PIC function, we inoculated CPSF6-depleted and CPSF6-mutant cells with HIV-1 particles and measured viral DNA integration into the host genome. A significant reduction in viral integration in these cells was detected and this defect was not a consequence of reduced reverse transcription or nuclear entry. Additionally, mutant viruses deficient in CA-CPSF6 binding showed no integration defect in CPSF6 mutant cells. Finally, sequencing analysis revealed that HIV-1 integration in the CPSF6 mutant cells was significantly redirected from the gene dense regions of the host genome. Collectively, these results suggest that CPSF6-CA interaction regulates PIC function both in vitro and in infected cells. IMPORTANCEHIV-1 infection is dependent on the interaction of the virus with host factors. However, the molecular details of virus-host factor interactions are not fully understood. For instance, HIV-1 capsid provides binding interfaces for several host factors. CPSF6 is one such capsid-binding host factor, whose cellular function is to regulate mRNA processing and polyadenylation. Initial work identified a truncated cytosolic form of CPSF6 that restricted HIV infection by blocking viral nuclear entry. However, it is now established that the full-length CPSF6 primarily promotes integration targeting into gene dense regions of the host genome. Here we report that CPSF6-CA interaction promotes the activity of HIV-1 preintegration complexes (PICs). We also observed that disruption of CPSF6-CA binding in target cells significantly reduced viral integration and directed integration targeting away from gene-dense regions. These findings demonstrate a critical role for the CPSF6-CA interaction in PIC function and integration targeting.

biochemistry↗

bioRxiv2024

Inducing a synergistic anti-obesity effect by increasing the bioavailability of the flavonoid rutin with a L. plantarum species

Flavonoids, plant-derived compounds, are broadly categorized into glycoside (sugar-bonded) and aglycone (sugar-removed) forms and are predominantly found as glycosides in nature. Rutin, a glycoside, is a widely recognized flavonoid with significant potential as an anti-obesity agent. However, its low bioavailability in the body presents challenges in obesity treatment. We aimed to enhance the bioavailability and anti-obesity effect of rutin through microbial involvement. Lactiplantibacillus plantarum HAC03, one of the candidates, demonstrated the ability to hydrolyze rutin into isoquercetin and quercetin in vitro. In a diet-induced obesity mouse model, the combination of rutin and the L. plantarum strain resulted in significant weight loss, reduced adipocyte size and lowered obesity-related biomarkers in the blood, decreased fat-synthesis related gene expression, and increased fatty acid {beta}-oxidation related gene expression compared to other test groups. This includes groups treated with rutin or quercetin alone or in combination with a different species from the same Lactobacillus genus, known for its anti-obesity effect but lacking the ability to hydrolyze rutin. This synergistic combination also alleviated insulin resistance and reduced fat in the liver. Gut microbiota analysis revealed localization of L. plantarum in the ileum and beneficial changes in disrupted microbiota in the intestine. These findings provide insights into underlying mechanisms causing the synergistic effect and suggest a novel combination that is as safe as microbial monotherapies with L. plantarum or L. rhamnosus but more effective in anti-obesity treatment.

microbiology↗

bioRxiv2024

Independent control of neurogenesis and dorsoventral patterning by NKX2-2

Human neurogenesis is disproportionately protracted, lasting >10 times longer than in mouse, allowing neural progenitors to undergo more rounds of self-renewing cell divisions and generate larger neuronal populations. In the human spinal cord, expansion of the motor neuron lineage is achieved through a newly evolved progenitor domain called vpMN (ventral motor neuron progenitor) that uniquely extends and expands motor neurogenesis. This behavior of vpMNs is controlled by transcription factor NKX2-2, which in vpMNs is co-expressed with classical motor neuron progenitor (pMN) marker OLIG2. In this study, we sought to determine the molecular basis of NKX2-2-mediated extension and expansion of motor neurogenesis. We found that NKX2-2 represses proneural gene NEUROG2 by two distinct, Notch-independent mechanisms that are respectively apparent in rodent and human spinal progenitors: in rodents (and chick), NKX2-2 represses Olig2 and the motor neuron lineage through its tinman domain, leading to loss of Neurog2 expression. In human vpMNs, however, NKX2-2 represses NEUROG2 but not OLIG2, thereby allowing motor neurogenesis to proceed, albeit in a delayed and protracted manner. Interestingly, we found that ectopic expression of tinman-mutant Nkx2-2 in mouse pMNs phenocopies human vpMNs, repressing Neurog2 but not Olig2, and leading to delayed and protracted motor neurogenesis. Our studies identify a Notch- and tinman-independent mode of Nkx2-2-mediated Neurog2 repression that is observed in human spinal progenitors, but is normally masked in rodents and chicks due to Nkx2-2s tinman-dependent repression of Olig2.

developmental biology↗

bioRxiv2024

Long-term single-molecule tracking in living cells using weak-affinity protein labeling

Single-particle tracking (SPT) has become a powerful tool to monitor the dynamics of membrane proteins in living cells. However, permanent labeling strategies for SPT suffer from photobleaching as a major limitation, restricting observation times, and obstructing the study of long-term cellular processes within single living cells. Here, we use exchangeable HaloTag Ligands (xHTLs) as an easy-to-apply labeling approach for live-cell SPT and demonstrate extended observation times of individual live cells of up to 30 minutes. Using the xHTL/HT7 labeling system, we measure the ligand-induced activation kinetics of the epidermal growth factor receptor (EGFR) in single living cells. Furthermore, we generate spatial maps of receptor diffusion in cells, report non-uniform distributions of receptor activation, and the formation of spatially confined hot spots of EGFR activation. This approach represents a general strategy to monitor protein dynamics in a functional context and for extended observation times in single living cells.

biophysics↗

bioRxiv2024

Structure of the human K2P13.1(THIK-1) channel reveals a novel hydrophilic pore restriction and lipid cofactor site

The halothane-inhibited K2P leak potassium channel K2P13.1 (THIK-1)1-3 is found in diverse cells1,4 including neurons1,5 and microglia6-8 where it affects surveillance6, synaptic pruning7, phagocytosis7, and inflammasome-mediated interleukin-1{beta} release6,8,9. As with many K2Ps1,5,10-14 and other voltage-gated ion channel (VGIC) superfamily members3,15,16, polyunsaturated fatty acid (PUFA) lipids modulate K2P13.1 (THIK-1)1,5,14,17 via a poorly understood mechanism. Here, we present cryo-electronmicroscopy (cryo-EM) structures of human K2P13.1 (THIK-1) and mutants in lipid nanodiscs and detergent. These reveal that, unlike other K2Ps13,18-24, K2P13.1 (THIK-1) has a two-chamber aqueous inner cavity obstructed by a M4 transmembrane helix tyrosine (Tyr273, the flow restrictor). This hydrophilic barrier can be opened by an activatory mutation, S136P25, at natural break in the M2 transmembrane helix and by intrinsic channel dynamics. The structures also reveal a buried lipid in the P1/M4 intersubunit interface at a location, the PUFA site, that coincides with the TREK subfamily K2P modulator pocket for small molecule agonists18,26,27. This overlap, together with the effects of mutation on K2P13.1 (THIK-1) PUFA responses, indicates that the PUFA site lipids are K2P13.1 (THIK-1) cofactors. Comparison with the PUFA-responsive VGIC Kv7.1 (KCNQ1)28-31 reveals a shared role for the equivalent pore domain intersubunit interface in lipid modulation, providing a framework for dissecting the effects of PUFAs on the VGIC superfamily. Our findings reveal the unique architecture underlying K2P13.1 (THIK-1) function, highlight the importance of the P1/M4 interface in control of K2Ps by both natural and synthetic agents, and should aid development of THIK subfamily modulators for diseases such as neuroinflammation6,32 and autism6.

biophysics↗

bioRxiv2024

SLIRP mediates nuclear-mitochondrial communication during antiviral signaling to promote robust interferon response

The abnormal innate immune response is a prominent feature underlying autoimmune diseases. One emerging factor that can trigger dysregulated immune activation is cytosolic mitochondrial double-stranded RNAs (mt-dsRNAs). However, the mechanism by which mt-dsRNAs stimulate immune responses remains poorly understood. Here, we discover SRA stem-loop interacting RNA binding protein (SLIRP) as a key amplifier of mt-dsRNA-triggered antiviral signals. In autoimmune diseases, SLIRP is commonly upregulated, and targeted knockdown of SLIRP dampens the interferon response. We find that the activation of melanoma differentiation-associated gene 5 (MDA5) by exogenous dsRNAs upregulates SLIRP, which then stabilizes mt-dsRNAs and promotes their cytosolic release to activate MDA5 further, augmenting the interferon response. Furthermore, the downregulation of SLIRP partially rescues the abnormal interferon-stimulated gene expression in autoimmune patients primary cells and makes cells vulnerable to certain viral infections. Our study unveils SLIRP as a pivotal mediator of interferon response through positive feedback amplification of antiviral signaling.

molecular biology↗

bioRxiv2024

Oligomeric HIV-1 Integrase Structures Reveal Functional Plasticity for Intasome Assembly and RNA Binding

Integrase (IN) performs dual essential roles during HIV-1 replication. During ingress, IN functions within an oligomeric "intasome" assembly to catalyze viral DNA integration into host chromatin. During late stages of infection, tetrameric IN binds viral RNA and orchestrates the condensation of ribonucleoprotein complexes into the capsid core. The molecular architectures of HIV-1 IN assemblies that mediate these distinct events remain unknown. Furthermore, the tetramer is an important antiviral target for allosteric IN inhibitors. Here, we determined cryo-EM structures of wildtype HIV-1 IN tetramers and intasome hexadecamers. Our structures unveil a remarkable plasticity that leverages IN C-terminal domains and abutting linkers to assemble functionally distinct oligomeric forms. Alteration of a newly recognized conserved interface revealed that both IN functions track with tetramerization in vitro and during HIV-1 infection. Collectively, our findings reveal how IN plasticity orchestrates its diverse molecular functions, suggest a working model for IN-viral RNA binding, and provide atomic blueprints for allosteric IN inhibitor development.

biochemistry↗