Biology subjects

Nguyen, H.

Publications and source records attributed to Nguyen, H..

At least 37 records · Page 2Linked to original sources

bioRxiv2026

Generation of a new immunodeficient rat model of retinal degeneration with LSL TdTomato reporter and TdTomato-Pcp2 expression

PurposeTo develop an immunodeficient retinal degenerate (RD) rat model with fluorescent label for studying retinal degeneration and transplant-host connectivity. MethodsGene constructs for CAG-LSL-TdTomato and Pcp2-Cre were developed and injected into rat embryos at Envigo. The LSL TdTomato reporter strain, created on immunodeficient RhoS334ter-3 rats (RRRC#539), was bred to homozygosity at UCI (strain SD-Foxn1rnuTg((Rho-S334X)3,CAG-TdTomato)1010Mjsuc, "RNT"). The second gene construct Pcp2-Cre was injected into Long-Evans (LE) rat embryos, resulting in two Pcp2-cre founders (strain PCP2 Cre-1105 RKI, "Pcp2"), with targeted and targeted/random insertion. Founders were mated with an LE male and a foxn1+/- NIH nude female. F1 offspring was bred to homozygosity and immunodeficiency. Homozygous rats of both strains were crossbred to generate TdTomato-Pcp2 RD ("RTP") rats. Retinas were processed for immunohistochemistry for various retinal markers. GFP-expressing rat retinas were transplanted to 6 week old "RTP" rats and analyzed 37 and 77 days post-surgery (pilot experiments). ResultsTdTomato-Pcp2 RD rats exhibit RD similar to the original Rho S334ter-3 rat strain, with < 1 row photoreceptors remaining at 1 month. Retinas with targeted Pcp2 insertion showed TdTomato in retinal interneurons and cones. Retinas with random Pcp2 insertion exhibited additional TdTomato in RPE, glial, and endothelial cells. Pcp2-TdTomato expression was useful to define transplant-host boundaries. ConclusionsWe created an unique RD rat model for studying retinal transplant connectivity. The RD LSL-TdTomato reporter rat can also be used to generate RD rats with other cell-specific labels using the cre/lox system. Translational relevanceThis newly created rat model is useful for cell therapy studies.

neuroscience↗

bioRxiv2026

3D, multi-omic imaging reveals molecular biomarkers of the pre-metastatic niche in lung cancer

The recurrence rate following complete surgical resection of primary non-small cell lung cancer is as high as 55%, yet no approach currently exists to evaluate the risk of local recurrence. The premetastatic paradigm is the recognition that metastasis is preceded by reprogramming naive tissues to prime a microenvironment for tumor cell survival and subsequent reactivation. Identification of biomarkers of the pre-metastatic niche would allow us to evaluate a patients risk of local relapse in the normal lung parenchyma surrounding the resected tumor. We designed a workflow incorporating in vivo modelling, radiology, and deep learning-guided three-dimensional (3D) imaging, spatial proteomics, and transcriptomics to identify previously unreported signals associated with the early transformation of the lung parenchyma announcing regional metastasis. We curated biorepository spanning timepoints before and after resection of primary Lewis Lung Carcinoma (LLC) tumors. Using radiology and cellular resolution 3D histology, we calculated the number and distribution of metastases in mouse lungs and developed an algorithm to guide placement of spatial proteomics and transcriptomics to regions containing early micro-metastases and the pre-metastatic microenvironment. Molecular and tissue features associated with presence, size, and location of metastases guided the identification of both myeloid (F4/80) and senescent (p16/p21) cell signatures in the premetastatic and metastatic environments. Finally, multiparametric flow cytometry of metastatic lungs in a senescence reporter GEMM (tdTomato-p16 INKA mice) resolved senescent cells including alveolar macrophages as the cellular phenotypes associated with these early premetastatic signatures. Altogether, this work highlights a novel AI-assisted approach for detection of biomarkers of tissue remodeling during lung cancer invasion.

bioengineering↗

bioRxiv2026

Outpacing E. coli: Development of Vibrio natriegens as a Next-Generation Cloning Host

Despite transformative advances in DNA synthesis, sequencing, and automation that have accelerated recombinant DNA workflows, molecular cloning hosts have scarcely evolved past the Escherichia coli strains adopted out of convenience in the 1970s. We present NBx CyClone - an engineered strain of Vibrio natriegens - as a next-generation host for molecular cloning. This non-pathogenic marine bacterium combines broad plasmid and genetic tool compatibility, a versatile metabolism, and the fastest known doubling time of any free-living organism. By shortening growth-dependent steps, this host offers a practical route to faster, more efficient recombinant DNA workflows across research and industry.

synthetic biology↗

bioRxiv2025

Template-based RNA structure prediction advanced through a blind code competition

Automatically predicting RNA 3D structure from sequence remains an unsolved challenge in biology and biotechnology. Here, we describe a Kaggle code competition engaging over 1700 teams and 43 previously unreleased structures to tackle this challenge. The top three submitted algorithms achieved scores within statistical error of the winners of the recent CASP16 competition. Unexpectedly, the top Kaggle strategy involved a pipeline for discovering 3D templates, without the use of deep learning. We integrated this template-modeling pipeline and other Kaggle strategies to develop a single model RNAPro that retrospectively outperformed individual Kaggle models on the same test set. These results suggest a growing importance of template-based modeling in RNA structure prediction.

biophysics↗

bioRxiv2025

Absence of MBP 3' UTR in Mice Disrupts mRNA Transport, Myelination, and Motor Learning

Myelin sheath maturation requires compaction, a cellular phenomenon mediated by local translation of myelin basic protein (MBP), which acts as a molecular zipper to join adjacent membranes and extrude the cytoplasm. Contrary to decades-old microinjection experiments indicating that Mbp mRNA transport is restricted to microtubules, we now show using smFISH that endogenous Mbp mRNA granules indeed localize along actin. To validate the in vivo necessity of Mbp mRNA transport and its dependence on the 3 UTR (untranslated region), we replaced the endogenous Mbp 3 UTR with polyA tail sequences. Though these mice have decreased Mbp mRNA levels, this alone could not account for their striking phenotypes - hypomyelination, baseline tremors, and motor learning defects. Thus, we cultured oligodendrocytes from these mice and found defects in both Mbp mRNA localization and local translation. These results demonstrate that the 3 UTR of a locally translated structural protein is critical for both developmental and activity-induced myelination.

cell biology↗

bioRxiv2025

De novo design of protein nanoparticles with integrated functional motifs

Computational design of self-assembling proteins has long relied on pre-existing structures and sequences, fundamentally limiting control over their structural and functional properties. Recent machine learning-based methods have transformed our ability to design functional small de novo proteins and oligomers, yet methods to design large de novo protein assemblies with structures tailored to specific applications are still underexplored. Here, we develop a generalizable method for designing de novo symmetric protein complexes that incorporate target functional motifs into their structures. We report 34 new protein nanoparticles that form on-target assemblies with cubic point group symmetries. The nanoparticles exhibit a wide variety of backbones that were designed with atom-level accuracy, as evidenced by several cryo-EM and crystal structures that reveal minimal deviations from the design models. We use the method to generate a de novo antigen-tailored nanoparticle vaccine that elicits robust immune responses in mice. These results establish a generalizable approach that can be used to design functional self-assembling protein complexes with structures tailored to specific applications.

biochemistry↗

bioRxiv2025

A single-cell cytokine dictionary of human peripheral blood

Cytokines orchestrate immune responses, yet we still lack a comprehensive understanding of their specific effects across human immune cells due to their pleiotropy, context dependence and extensive functional redundancy. Here, we present a Human Cytokine Dictionary, created from high-resolution single-cell transcriptomes of 9,697,974 human peripheral blood mononuclear cells (PBMC) from 12 donors stimulated in vitro with 90 different cytokines. We describe donor-specific response variation and uncover robust consensus cytokine signatures across individuals. We then delineate similarities between cytokine response profiles, and derive cytokine-induced immune programs that organize responsive genes into data-driven, biologically interpretable functional modules. By integrating cell type-specific responses with expression of cytokines, we infer higher-order cell-to-cell and cytokine-to-cytokine communication networks exemplified by an IL-32-{beta}-initiated signaling cascade, which rewires myeloid programs by inducing neutrophil-recruiting factors while suppressing Th1-responses and promoting IL-10-family cytokines. Finally, we show how the Human Cytokine Dictionary enables the interpretation of cytokine-driven immune responses in other studies and disease contexts, including systemic lupus erythematosus, multiple sclerosis, and non-small cell lung carcinoma. Together, the Human Cytokine Dictionary constitutes the first comprehensive cell type-resolved transcriptional screen of human cytokine responses and provides an essential open-access, easy-to-use community resource with accompanying software package to advance our understanding of cytokine biology in human disease and guide therapeutic discovery.

immunology↗

bioRxiv2025

Machine Learning-Augmented Analysis of Nano-electrochemical Sensor Data for Predictive and Quantitative Assays of Complex Biological Samples

Analytical chemistry provides the content of nearly every scientific, technical and business decision relating to what atoms, molecules and devices are and how they interact in their environment. Various workflows come together in describing those interactions--separation, identification, quantitation, classification--to inform decisions across society. Each workflow has associated equipment, infrastructure and subject matter experts that integrate results for input into those decisions. However, those existing workflows are constrained by their evolution and often require integrated applications of the multiple analytical techniques integrated to form conclusions, thereby increasing cost, complexity and quality. This paper describes an alternative approach to addressing the many limitations of contemporary analytical chemistry. Here machine learning is leveraged to analyze high dimensional data derived from a nano-electrochemical sensor platform, to perform classification, identification and quantitation analyses in an integrative manner from a single-shot measurement. The approach described here for biological samples does not require sample-specific preparation or marker-specific probes and labels to identify and/or quantitate the analyte of interest, thereby liberating the physical measurement of the sample from chemicals and workflows that are tied to the underlying biochemical hypothesis. The nano-electrochemical sensor, as described in a prior publication, transduces the vibrational frequencies of multiple species in the sample into a collection of discrete electronic signatures that represent the sample in a high dimensional space, while using only 2-4{micro}l sample volume. The sample analysis relies on training data to identify features in the high dimensional input dataset that are unique to the molecule or phenotype under consideration and distinct from the sample background matrix and/or a set of defined sample controls. The molecule- or phenotype-associated features can be tracked with clinically identified disease burden in the patient or with biomolecule concentration in the biological sample. The identification of patients with dementia from a plasma test is outlined here to demonstrate the applicability of this approach to classifying phenotypes associated with complex neurological disorders in a marker-agnostic manner. This approach is applied to a specific and quantitative assay of insulin Humalog and insulin Toujeo in a batch that comprises of a mixture of the two peptides, where Toujeo differs from Humalog in three amino acids residues only. We also describe the development of an assay for IL-6 in spiked human plasma samples with this method, thereby demonstrating the applicability of this analysis paradigm to more complex samples and protein-like species.

bioengineering↗

bioRxiv2025

Why PAR is not RNA: ion atmospheres, bridging interactions, and ion-induced structural collapse

Poly(ADP-ribose) (PAR) is a highly charged, intrinsically flexible nucleic-acid-like homopolymer composed of ADP-ribose units. It serves as a critical post-translational modification that rapidly synthesized in response to DNA damage, and participates in diverse important cellular processes, including DNA repair, chromatin remodeling, and RNA biogenesis, often by promoting biomolecular phase separation. However, PARs conformational heterogeneity coupled with limited experimental characterization has hindered a mechanistic understanding of these processes. To address this challenge, we develop a five-bead coarse-grained model of PAR and perform molecular dynamics simulations to compare its conformational ensemble and ion atmosphere with those of RNA across diverse ion environments. Our simulations reveal that PAR undergoes a markedly stronger structural transition than RNA in response to divalent ions, driven by its preferential ion binding and effective ion-mediated bridging between phosphate groups. These interactions facilitate cooperative conformational changes and produce a compact, ion-rich atmosphere that is fundamentally distinct from RNA. Together, our work provides a physically grounded model for PAR, uncovers molecular features that differentiate PAR from RNA, and offers mechanistic insight into how PAR nucleates phase separation and organizes protein interactions at sites of DNA damage.

biophysics↗

bioRxiv2025

Computational design of cysteine proteases

Despite advances in de novo enzyme design, success has been largely limited to low energy barrier model reactions. Amide bonds such as those linking amino acids along the peptide backbone are stable for hundreds of years in neutral aqueous solution because of the high energy barrier to hydrolysis. Here we describe the de novo design of enzymes which utilize an activated cysteine nucleophile to hydrolyze the polypeptide backbone in a sequence-dependent manner, with a success rate of 13/69=19% and rate enhancements over the background reaction (kcat/kuncat) of up to 3 x 10^7. The designed proteases have folds very different from proteases in nature (TM score < 0.50), and six crystal structures are very close to the design models (Ca RMSDs < 1.2 A), highlighting the capacity for generalization and the accuracy of the design methodology. Experimental and computational analyses suggest that the remaining gap in activity to the most active native cysteine proteases arises from imperfections in active site preorganization and substrate positioning. The designed proteases efficiently cleave their targets in mammalian cells, opening the door to a wide range of synthetic biology applications.

biochemistry↗

bioRxiv2025

Defective Microhomology-Mediated End-joining in SMARCB1-Deficient Tumors

Rhabdoid tumors (RTs) are highly aggressive cancers driven by biallelic mutation of SMARCB1, a core subunit of the BAF (SWI/SNF) complex. We found that SMARCB1-deficient tumors have a defect in the microhomology-mediated end-joining (MMEJ) pathway, and SMARCB1 is essential for maintaining the protein level of the core MMEJ protein Polymerase Q (POLQ). Mechanistically, SMARCB1 facilitates the nuclear export of the POLQ mRNA through its interaction with the nuclear pore complex. Interestingly, loss of MMEJ in RT cells leads to a compensatory activation of, and a hyper-dependence on, the Fanconi Anemia (FA)/BRCA pathway. Knockout or inhibition of this pathway selectively kills RT cells. Notably, RBM39 degraders, novel splicing modulators, effectively inhibit the FA/BRCA pathway and kill RT cells. SMARCB1 and other cBAF/pBAF components are important for maintenance of MMEJ activity and POLQ protein level, suggesting that BAF-deficient cancers more broadly may be treated by targeted inhibition of the FA/BRCA pathway. TeaserSMARCB1-deficient tumors lose POLQ protein and MMEJ repair, forcing a hyper-dependence on the FA/BRCA pathway.

cancer biology↗

bioRxiv2025

Effects of ΔmotY mutations on motility behavior of Pseudomonas aeruginosa chimeric periplasmic stator variants

Pseudomonas aeruginosa utilizes dual flagellar stator systems for motility; and dual stator bacteria possess auxiliary flagellar rotor ring components in their periplasm. In P. aeruginosa MotAB and MotCD comprise the dual stator system and MotY is the auxiliary periplasmic ring component. We investigated motility of strains and their isogenic {Delta}motY derivatives which expressed chimeric MotB/MotD periplasmic domains and characterized differences in motility behaviors. We found in general motility is severely impaired in strains carrying motY deletions and which express C-terminal periplasmic regions of MotD, compared with strains expressing MotB C-terminal counterparts. Motility in soft agar is slightly increased in strains expressing N-terminal MotB transmembrane domains and MotD C-terminal periplasmic plug, PGB, and extensions, but motility is severely impaired in {Delta}motY strains. Addition of the extended 24-residue C-terminus of MotB to the C-terminus of MotD does not significantly affect either motility or compensate for the deleterious effect of {Delta}motY mutation, but does significantly increase motility in motY+ backgrounds. The soft agar motility results for organisms with wild type MotAB stators was not different from those with MotAB stators carrying 24 residue MotB C-terminal deletions; however, motility of these mutants was significantly lower in {Delta}motY mutants compared to {Delta}motY mutants expressing wild type MotAB stators. We discuss contributions of stator functional domains to motility and the effects of {Delta}motY deletion. Lastly, we speculate on possible mechanistic roles for the two stator plug types based on thermodynamic considerations related to differences in composition of the hydrophobic surfaces of the two amphipathic helices. IMPORTANCEPseudomonas aeruginosa uses two torque-generating stators, MotAB and MotCD, to drive flagellar rotation. Dual stator bacteria have additional rotor components; in P. aeruginosa, this component has been identified as MotY. This study investigates the interaction between the C-terminal plug and periplasmic regions of the MotB and MotD components of the MotAB and MotCD stator complexes with MotY. Motility assays of periplasmic chimeric strains expressing variants with MotB and MotD C-terminal plug and peptidoglycan binding domains reveal an enhanced sensitivity of MotD C-terminus to MotY deletions. These data suggest that critical interactions, either direct or indirect, must take place between the basal body MotY ring complex and MotD periplasmic regions for proper function of the MotCD stator in flagellar motility.

microbiology↗

bioRxiv2025

Temperature-Dependent Ion Migration Underlies Sequence-Specific RNA Collapse

Ions and temperature jointly regulate RNA structure, dynamics and phase behavior, yet their coupled effects remain poorly understood at the molecular level. Single-stranded RNA (ssRNA), a ubiquitous and functionally versatile class of RNA, presents a particularly challenging target due to its intrinsic flexibility and pronounced sensitivity to ionic and thermal perturbations. Here, we extend our previously validated coarse-grained RNA model by introducing temperature-dependent divalent ion-phosphate potentials along with revised stacking interactions to elucidate how electrostatics, stacking, and hydration collectively determine ssRNA behavior. Our simulations quantitatively reproduce experimental SAXS profiles across a broad range of ionic conditions and reveal a non-monotonic temperature dependence of RNA compaction: ssRNAs expand upon heating, reach a sequence-specific maximum size, and then collapse as enhanced counterion condensation dominates. Rising temperature strengthens ion-RNA interactions, leading to a reorganization from diffusive to inner-sphere coordination, directly linking RNA collapse to ion dehydration. Our results establish that the ion atmosphere is a dynamic, sequence-encoded extension of RNA structure. This framework provides molecular insight into how temperature and ions govern RNA conformational transitions, offering a microscopic basis for RNA thermoadaptation, cold-induced misfolding, and RNA phase transitions. Statement of SignificanceIons and temperature strongly influence RNA structure and dynamics, yet the molecular mechanisms by which these factors jointly regulate RNA behavior remain poorly understood. Using coarse-grained simulations with temperature-dependent Mg2+-phosphate interactions, we report how ion binding reorganizes around single-stranded RNAs as temperature increases. We found that unstructured RNAs undergo a non-monotonic structural transition: thermal disruption of base stacking first expands the chain, followed by the collapse driven by enhanced Mg2+ binding. This collapse arises from a temperature-induced migration of Mg2+ from diffusive ion atmosphere to direct inner-sphere binding, linking RNA compaction to ion dehydration and entropy-driven binding. These results reveal that the RNA ion atmosphere is a dynamic, structure-coupled component of RNA organization and provide a mechanistic basis for thermoresponsive RNA condensation. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=111 SRC="FIGDIR/small/683600v3_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@fe79beorg.highwire.dtl.DTLVardef@eaac88org.highwire.dtl.DTLVardef@e52bc1org.highwire.dtl.DTLVardef@19bbea0_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2025

Functional and dysfunctional T regulatory cell states in human tissues in RA and other autoimmune arthritic diseases

Regulatory T cells (Tregs), characterized by FOXP3 expression, are essential for maintaining immune homeostasis by controlling inflammation. However, in autoimmune diseases such as rheumatoid arthritis (RA), impaired Treg function contributes to immune dysregulation and disease pathology. While most studies of human Tregs have focused on blood, here we analyzed Tregs in synovial tissues from RA patients using single cell RNA sequencing (scRNAseq). We identified two predominant Treg states, CD25hiCXCR6pos Tregs with strong suppressive function, and CD25loAREGpos Tregs, a dysfunctional state exclusively enriched in synovial tissues but not in blood. Computational and in vitro analyses revealed that cortisol induced AREG expression, suppressed glycolysis, and impaired the suppressive function of CD25loAREGpos Tregs. In turn, AREG promoted an IL-33+ inflammatory phenotype in synovial fibroblasts. Importantly, we found that TNFR2 engagement can prevent or reverse this dysfunctional Treg state. In contrast to CD25loAREGpos Tregs, CD25hiCXCR6pos Tregs were highly suppressive, showed coordinated abundance with macrophages in synovial tissue, and functionally interacted with membrane-bound TNF expressed by macrophages, which promoted their functional suppressive state. These two Treg subsets were similarly found in the synovial tissue in Juvenile Idiopathic Arthritis (JIA), another inflammatory arthritic disorder, indicating conserved mechanisms across arthritic diseases. Together, our findings define distinct pathways driving divergent functional and dysfunctional Treg states in inflamed tissues and point to interventions that may prevent or reverse the development of the dysfunctional state.

immunology↗

bioRxiv2025

High-density theta burst stimulation (hdTBS) at 100 Hz triples the aftereffects of the conventional intermittent TBS

Slice electrophysiological studies have experimentally demonstrated that theta burst stimulation, consisting of electrical pulses delivered at 10 ms (100 Hz) inter-pulse intervals, optimally induces long-term potentiation in the hippocampus. Inspired by this observation, a novel transcranial magnetic stimulation (TMS) paradigm, 100 Hz high-density theta burst stimulation (100 Hz hdTBS), is presented. This paradigm delivers 6 pulses per burst with an inter-pulse interval of 10 ms - doubling the pulse frequency and total pulse count of the conventional intermittent TBS (iTBS). The effect of this new paradigm was studied in the motor cortex of awake rats using a rat-specific focal TMS coil and a hdTBS stimulator developed in house. Results reveal that 100 Hz hdTBS triples the after-effects of conventional iTBS. In a separate group of animals that received two consecutive iTBS session back-to-back (prolonged iTBS), we observed an inhibitory effect. Since that prolonged iTBS matches the total pulse count of 100 Hz hdTBS but produced opposite after-effects, our results underscore the critical roles of the temporal structure of TMS pulses--not merely the total number of pulses--in driving neuroplasticity. This new paradigm has the potential to significantly enhance therapeutic efficacy if confirmed to be safe and effective in humans.

neuroscience↗

bioRxiv2025

PGRP-LA regulates peritrophic matrix synthesis and influences trypanosome infection outcomes in tsetse flies

Peptidoglycan Recognition Proteins (PGRPs) are conserved pattern-recognition receptors that detect microbe-associated molecular patterns (MAMPs) and activate host immune responses. Compared to other dipterans, the tsetse fly (Glossina morsitans morsitans) genome encodes only five PGRPs-PGRP-LA, -LB, -LC, -SA, and -SB - far fewer than most dipterans, likely reflecting its sterile blood diet and streamlined microbiota. Here, we identify PGRP-LA as a critical regulator of peritrophic matrix (PM) integrity in the cardia (proventriculus), the tissue responsible for PM production. The PM is a chitinous sleeve-like barrier that separates the midgut epithelium from the ingested bloodmeal, supporting digestive homeostasis and infection resistance. We show that pgrp-la is prominently expressed in the cardia, transiently induced after a bloodmeal in newly eclosed flies, and reinduced following subsequent feedings, likely in response to blood-constituents or mechanical stretch. This induction is sustained during microbial exposure and prolonged in trypanosome-infected flies. RNAi-mediated reduction of pgrp-la significantly increased the prevalence of midgut trypanosome infections, indicating a protective role during early infection. PGRP-LA did not mediate infection resistance via canonical IMD pathway signaling, as its silencing did not affect antimicrobial peptide expression. Instead, PGRP-LA modulated the expression of PM-associated genes and gut barrier integrity. Silencing pgrp-la reduced PM structure, increased midgut weights and enhanced fly survival following oral challenge with entomopathogen Serratia marcescens, likely due to earlier epithelial immune responses through a compromised PM. Similar phenotypes were observed when flies were fed anti-PGRP-LA antibodies, supporting a structural role for PGRP-LA. In addition, soluble variant surface glycoproteins (sVSGs) from trypanosomes and knockdown of microRNA-275 (miR-275), also decreased pgrp-la expression, suggesting that PGRP-LA is part of a broader regulatory network, including the miR-275/Wingless signaling. Collectively, our results identify PGRP-LA as novel regulator of PM biogenesis and vector competence in tsetse, expanding the functional repertoire of PGRPs in insect gut barrier maintenance beyond canonical immune signaling pathways. Author SummaryInsect vectors such as tsetse flies can be infected with pathogens that cause devastating disease in mammals. To protect themselves insect vectors rely on pattern recognition receptors (PRRs) that detect pathogens and activate the production of antimicrobial peptides (AMPs). Physical barriers in the gut also play an important role in limiting infections. One such barrier is the peritrophic matrix (PM), a sleeve-like structure that lines the insect gut and separates the blood meal and its contents from the underlying cells. For trypanosome parasites, which cause sleeping sickness in humans, the PM is the first barrier they must traverse to colonize the tsetses gut. In this study, we identified a PRR, PGRP-LA, that, unlike related proteins in other insects that activate AMPs, regulates the integrity of the tsetses protective PM barrier. When PGRP-LA was disrupted, the gut barrier weakened, and flies became more susceptible to trypanosome infection. Our work highlights a previously unrecognized role for PGRP-LA in maintaining gut barrier integrity and suggest that targeting this pathway could be a strategy to help reduce parasite transmission.

immunology↗

bioRxiv2025

Human CDK5-cyclin B1 structures uncover a conserved mitotic CDK activation mechanism

Cyclin-dependent kinase 5 (CDK5), long considered atypical and activated by non-cyclin cofactors in neurons, also functions in mitosis. To resolve its activation mechanism during mitosis, we determined the first high-resolution crystal structures of CDK5-cyclin B1 in apo and nucleotide-bound states. Contrary to AlphaFold predictions, we find CDK5 structures unexpectedly mirrors CDK1-cyclin B1 assembly and activation, establishing CDK5 as a bona fide mitotic kinase acting in parallel with CDK1.

biochemistry↗

bioRxiv2025

Cellular and Molecular Architecture of Renin-Angiotensin System Signaling in the PVN Under Cardiometabolic Stress

The hypothalamic paraventricular nucleus (PVN) integrates neuroendocrine and autonomic signals that regulate blood pressure and metabolism. Although the renin- angiotensin system (RAS) is implicated in neurogenic hypertension and obesity, cell-type- specific expression and regulation of its components within the PVN remain poorly understood. Here, we employed single-nucleus RNA sequencing (snRNA-seq) to profile the transcriptomic landscape of the PVN in male mice under baseline conditions and in models of DOCA-salt-induced hypertension and high-fat diet (HFD)-induced obesity. We identified major PVN cell types, including neurons, astrocytes, precursor oligodendrocytes, oligodendrocytes, microglia and endothelial cells, and further resolved eight transcriptionally distinct neuronal subtypes. Expression of RAS-related genes was highly cell-type specific: Agt (angiotensinogen) was enriched in astrocytes, whereas Ace (angiotensin-converting enzyme), Atp6ap2 (also known as the (pro)renin receptor [PRR]), Agtr1a (angiotensin II type 1a receptor, aka AT1aR), Lnpep (leucyl/cystinyl aminopeptidase, aka angiotensin 4 receptor [AT4R]), and the Mas1 proto-oncogene were predominantly expressed in neurons. DOCA-salt treatment increased the proportion of GABAergic and vasopressin neurons and enhanced neuronal Agt and Atp6ap2 expression, while reducing astrocytic Agt, suggesting activation of a vasoconstrictive RAS axis. HFD exposure increased excitatory and stress-responsive neuronal subtypes (glutamatergic, vasopressin, corticotropin-releasing hormone) and upregulated Atp6ap2, Agtr1b, Lnpep, and Mas1 in vasopressin neurons, while downregulating multiple RAS genes in GABAergic neurons. These findings reveal dynamic, cell-type-specific remodeling of RAS signaling in the PVN in response to hypertensive and metabolic stress, providing a transcriptomic atlas of RAS expression in the PVN and identifying potential cellular targets for therapeutic strategies addressing cardiometabolic disorders.

genomics↗