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Biology subjects

Zhou, J.

Publications and source records attributed to Zhou, J..

At least 127 records · Page 7Linked to original sources

Distinct Programs Drive Organ Development and Regeneration

A prevailing paradigm in stem cell and developmental biology posits that regeneration is a recapitulation of embryonic programs, yet the molecular logic underlying these processes remains unclear. Here, using the mammary gland as a model, we identified a novel intermediate cell state essential for basal-to-luminal differentiation during regeneration. The transcription factor Pou2f3 is a master regulator of this state, critical for regeneration but dispensable for organ physiology. Mechanistically, we found that POU2F3 functions as a transcriptional repressor that drives lineage conversion by restricting chromatin accessibility of basal genes rather than by directly activating luminal programs. Furthermore, we uncovered a POU2F3-TNF feedback loop that maintains epithelial homeostasis, where TNF signaling suppresses Pou2f3 to inhibit differentiation, and loss of luminal cells relieves this repression to trigger regeneration. Strikingly, cell fate is governed by signaling pathways essential for cell-cell communication during development, but by Pou2f3-dependent chromatin remodeling for rapid response and injury repair. We validate the regeneration-specific requirement for Pou2f3 in mammary gland and further demonstrate analogous regeneration defects in prostate and pancreas. These findings challenge the long-held assumption that regeneration recapitulates development and establish a framework for understanding context-specific mechanisms of tissue plasticity, with implications for regenerative medicine and epithelial biology.

cell biology↗

Immune-Derived THBS1-CD47 Axis Induces Cellular Senescence and Suppresses Osteogenesis in Diabetic Periosteum

Type 2 diabetes mellitus (T2DM) weakens bone repair and increases fracture risk, but how the periosteal environment contributes to this problem is not fully understood. We found that diabetic mice showed thinning of the periosteum, reduced bone mass, and poor function of bone-forming cells. Using single-cell RNA sequencing, we discovered that immune cells and bone-lineage cells interact more strongly in diabetes through the THBS1-CD47 pathway. THBS1 was mainly produced by macrophages, while its receptor CD47 was abundant in osteogenic cells. Laboratory experiments showed that THBS1 blocked bone gene activity, increased inflammation and cell death, and damaged mitochondria, leading to higher oxidative stress. Knocking down CD47 reversed these effects, restoring bone cell activity and energy balance. In diabetic fracture models, blocking THBS1 improved callus formation and bone healing. These findings identify THBS1-CD47 as a key driver of periosteal dysfunction in T2DM and highlight it as a potential target to improve skeletal repair in diabetic patients.

cell biology↗

Brain-wide Genome Editing via STEP-RNPs for Treatment of Angelman Syndrome

Brain-wide genome-editing remains a major hurdle for the treatment of neurogenetic disorders. Here, we report a non-viral, non-nanoparticle, chemical modification-based method, called Stimuli-Responsive Traceless Engineering Platform (STEP) that achieves highly efficient and brain-wide genome-editing of neurons in mice. Using cholesterol-based STEP as a lead, we show that a single administration of STEP-ribonucleoproteins (RNPs) results in functional genetic rescue with significant improvements across a battery of neurobehavioral domains in the Angelman syndrome (AS) mouse model. No significant off-target events or general toxicity effects are observed. STEP-RNPs are also highly efficient at editing human neurons and cortical brain organoids differentiated from AS patient-derived iPSCs. scRNA-seq analysis confirms functional genetic rescue via reactivation of Ube3a/UBE3A expression in human and mouse STEP-RNP-treated neuronal cells. Genome editing via STEP-RNPs has broad applications and the potential to treat many other neurogenetic disorders.

genetics↗

Structural and Functional Insights into HBx-Smc6 Targeting for HBV Inhibition

The hepatitis B virus (HBV) X protein (HBx) is a multifunctional regulator essential for HBV replication and HBV-associated hepatocarcinogenesis. Despite its central role, the molecular basis of HBx function has remained elusive. Here, we present the first cryo-electron microscopy structure of the human HBx-CRL4-Smc5/6 complex at 3.1 [A] resolution. In this reconstituted ten-subunit assembly, HBx adopts a Zn2 {square}-stabilized Y-shaped architecture that simultaneously engages the DDB1 and the Smc6 subunit. A composite helix-turn-helix (HTH) pocket in HBx accommodates a conserved "Leucine Key" motif (LRCKL) on Smc6, forming a critical interface essential for complex stability and function. Molecular docking and biochemical validation reveal that the compound Tranilast binds this HTH pocket, disrupts the HBx-Smc6 interaction, and suppresses HBV replication. These findings define the structural mechanism by which HBx counteracts host restriction and establish the HBx-Smc6 interface as a previously unrecognized and druggable target for antiviral intervention.

cell biology↗

Ancestral neuronal receptors are bacterial accessory toxins

Symbiosis and horizontal gene transfer events were crucial in the emergence of eukaryotic and multicellular life. A striking example is the acquisition of Teneurins, putative surface-exposed toxins in bacteria that function as cell adhesion receptors in metazoan neuronal development. Here, we demonstrate the evolutionary relationships between metazoan and bacterial Teneurins. We show that bacterial Teneurins are accessory proteins, that harbour diverse encapsulated toxins. They predominate in species with complex social behaviours, suggesting roles in both cell-to-cell competition and cooperation. Metazoan Teneurins are therefore repurposed bacterial toxins central to cell-to-cell communication in nervous systems. Their acquisition was a foundational event in the evolution of metazoans.

biochemistry↗

Inter- and intra-individual differences in temporal modulation patterns of the β-band sensorimotor rhythm and its relationship to corticomuscular coherence during intermittent voluntary contraction

The {beta}-band sensorimotor rhythm (SMR), recorded using electroencephalography, generally begins to decrease in amplitude with motor preparation reflecting cortical desynchronization, and subsequently becomes coupled with electromyogram signals during voluntary contraction, thus forming corticomuscular coherence (CMC). However, it remains unclear how the time-resolved modulation of {beta}-band SMR varies among individuals, potentially relating to individual differences in CMC. Additionally, it is also unclear how the nervous system modulates {beta}-band SMR to meet varying task demands within individuals. Here, we explored how time-resolved modulation patterns of {beta}-band SMR relate to CMC from two perspectives: inter-individual differences (Experiment 1), and intra-individual variability depending on task demands (Experiment 2). In Experiment 1, participants repeated a steady-force maintenance task. The degree of {beta}-band SMR modulation (i.e., rebound from desynchronization to synchronization) during contractions varied greatly among individuals and was positively correlated with CMC magnitude. This suggests that even under steady-force maintenance, the motor control strategy used while regulating {beta}-band SMR varies greatly among individuals. In Experiment 2, participants who showed significant CMC in Experiment 1 performed four tasks with varying target trajectories. Even within individuals, the degree of {beta}-band SMR modulation was reduced in parallel with the CMC magnitude as force adjustment was required. This finding suggests that, when confronted with more challenging task demands, our nervous system suppresses the SMR modulation and decouples from muscles. Overall, the way in which our nervous system regulates {beta}-band SMR is assumed to represent a strategy for flexible adaptation to diverse motor environments.

neuroscience↗

Bridging Language Markers and Pathology: Correlations Between Digital Speech Measures and Surrogate CSF Biomarkers in Alzheimer's Disease

BackgroundDigital language markers show promise in detecting early cognitive impairment related to Alzheimers disease (AD), yet their relationship with cerebrospinal fluid (CSF) biomarkers of AD pathology remains unclear mainly due to the lack of data with both CSF and language markers. ObjectiveThis study aims to build links between digital language markers and fluid biomarkers through surrogate CSF biomarkers. MethodsUsing NACC clinical data as anchor variables, language makers in the I-CONECT study were linked to NACC CSF data. Surrogate CSF biomarkers were created for I-CONECT subjects using machine learning models from common NACC clinical variables. Correlations assessed associations between CSF and language markers. ResultsLower predicted amyloid-{beta} correlated significantly with reduced syntactic complexity and shorter speech responses. Higher predicted total tau and phosphorylated tau correlated with reduced syntactic complexity. ConclusionsThis study demonstrates novel links between language markers and fluid biomarkers, highlighting conversational language as a potential accessible, non-invasive approach for early detection and monitoring of Alzheimers pathology.

bioinformatics↗

Discovery of Small Molecules and a Druggable Groove That Regulate DNA Binding and Release of the AP1 Transcription Factor DeltaFOSB

{Delta}FOSB, a member of the AP1 family of transcription factors, mediates long-term neuroadaptations underlying drug addiction, seizure-related cognitive decline, dyskinesias, and several other chronic conditions. AP1 transcription factors are notoriously difficult to modulate pharmacologically due to the absence of well-defined binding pockets. Here, we identify a novel site on {Delta}FOSB, located outside the DNA-binding cleft, that accommodates small molecules. We show that sulfonic acid-containing compounds bind to this site via an induced-fit mechanism, reorienting side chains critical for DNA binding, and that they may hinder the {Delta}FOSB bZIP -helix from binding to the major groove of DNA. In vivo, direct administration of one such compound, JPC0661, into the brain reduces {Delta}FOSB occupancy at genomic AP1 consensus sites by approximately 60% as determined by CUT&RUN-sequencing. These findings suggest that DNA binding and release by AP1 transcription factors can be controlled via small molecules that dock into a novel site that falls outside of the DNA-binding cleft. Minimal sequence conservation across 29 bZIP domain-containing transcription factors in this druggable groove suggests that it can be exploited to develop AP1-subunit-selective compounds. Our studies thus reveal a novel strategy to design small-molecule inhibitors of {Delta}FOSB and other members of the bZIP transcription factor family.

neuroscience↗

Efficient in vivo pharmacological inhibition of deltaFOSB, an AP1 transcription factor, in brain

{Delta}FOSB, an unusually stable member of the AP1 family of transcription factors, mediates long-term maladaptations that play a key role in the pathogenesis of drug addiction, cognitive decline, dyskinesias, and several other chronic neurological and psychiatric conditions. We have recently identified that 2-phenoxybenzenesulfonic acid-containing compounds disrupt the binding of {Delta}FOSB to DNA in vitro in cell-based assays, and one such compound, JPC0661, disrupts {Delta}FOSB binding to genomic DNA in vivo in mouse brain with partial efficiency. JPC0661 binds to a groove outside of the DNA-binding cleft of the {Delta}FOSB/JUND bZIP heterodimer in the co-crystal structure. Here, we generated a panel of analogs of JPC0661 with the goal of establishing structure-activity relationships and improving its in vivo efficacy by replacing the amino-pyrazolone cap moiety with various substituents. We show that one such analog, YL0441, disrupts the binding of {Delta}FOSB to DNA in vitro and in vivo, and suppresses {Delta}FOSB-function in cell-based assays. Importantly, infusion of YL0441 into the hippocampus of APP mice (a mouse model for Alzheimers disease) leads to virtually complete loss of {Delta}FOSB bound to genomic DNA by CUT&RUN sequencing. Our findings corroborate that DNA binding/release of AP1 transcription factors can be controlled via small molecules, even by analogs of a compound that binds to a groove outside of the DNA-binding cleft, and that our lead can be optimized via medicinal chemistry to yield a highly efficacious inhibitor of {Delta}FOSB function in vivo. These findings define a strategy to design small-molecule inhibitors for other AP1- and AP1-related transcription factors. IN BRIEFWe demonstrate the creation of a highly effective inhibitor, YL0441, of {Delta}FOSB, an AP1 transcription factor, which decreases the number of {Delta}FOSB-bound sites to genomic DNA by [~]94% upon in vivo infusion to the hippocampus of APP mice, a mouse model for Alzheimers disease. This work generates a highly novel probe compound to assess the therapeutic value of {Delta}FOSB in vivo, a transcription factor with a critical role in mediating long-term changes in gene expression in several neuropsychiatric disorders in addition to Alzheimers disease, including drug addiction, seizure-related cognitive decline, and dyskinesias.

neuroscience↗

ACE2 Phosphorylation Modulates Angiogenesis via the Activator Protein-1

BackgroundAngiogenesis plays a crucial role in organ development. However, aberrant blood vessel growth is involved in various diseases, including tumors and neovascular eye diseases. Angiotensin-converting enzyme 2 (ACE2) is a critical enzyme regulating the health of cardiovascular system, and its post-translational modifications (PTMs) are crucial to determine ACE2 expression level and activity. Here, we studied how the PTM of ACE2 in vascular endothelial cells (ECs) affect pathological retinal neovascularization and tumor angiogenesis. MethodsThe angiogenic capabilities of ECs were assessed by tube formation, sprouting assays, and 5-ethynyl-2-deoxyuridine (EdU) and filopodia staining. EC angiogenesis was examined by poteome profiler array and aortic ring assays in vitro and by the oxygen-induced retinopathy (OIR) and tumor angiogenesis models in vivo. High-throughput screening involving data from RNA-seq, ATAC-seq, and ChIP-seq were used to explore the epigenetic and transcriptional regulations of pro-angiogenic genes regualtged by ACE2 PTMs. ResultsACE2 Ser-680 dephosphorylation in connection with Lys-788 ubiquitination increased EC angiogenic phenotype, which were manifested by aberrant vascularization in mouse OIR and tumor models. ACE2 Ser-680 dephosphorylation led to the activation of activator protein-1 (AP-1), which transactivated multiple genes involved in angiogenesis. AP- 1 inhibition mitigated such angiogenesis in vivo. ConclusionOur findings show a novel PTM mechanism of ACE2 involved in pathological angiogeneis. Specifically, ACE2 Ser-680 dephosphorylation facilitated AP-1 transactivation of the downstream pro-angiogenic genes in ECs.

cell biology↗

The effects of denifanstat on hepatitis E virus replication and triggered inflammatory response

Metabolic dysfunction-associated steatotic liver disease (MASLD) is initiated by intra-cellular fatty acid accumulation, with macrophage-mediated inflammatory responses playing a pivotal role in driving disease progression. MASLD frequently coexists with viral infections, for example in the context of hepatitis E virus (HEV) infection which explores host lipid metabolism for its replication and secretion. But no targeted therapies currently exist for this complex comorbidity. Denifanstat, a fatty acid synthase (FASN) inhibitor developed for treating metabolic dysfunction-associated steatohepatitis (MASH), has shown to have antiviral activity against SARS-CoV-2 infection. In this study, we aim to assess the effects of denifanstat on HEV infection in the context of steatotic liver disease. We first employed human liver-derived primary organoids exposed to fatty acids and inoculated with HEV. Treatment with denifanstat had no major effect on HEV replication in the steatotic organoids. However, we found that denifanstat moderately inhibited viral replication in macrophages, and regulated HEV-triggered inflammatory responses. These results highlight the importance of understanding how the emerging MASH treatment may affect viral infections that coexist in patients.

microbiology↗

Elevated Temperatures Representing Heatwave Conditions Shift Active Nitrifying Communities and Their Viruses in Tidal Flats and Agricultural Soils

Global heatwave intensification associated with climate change will impact the nitrogen cycle, yet its effect on specific nitrifier groups or their interactions with viruses remains unclear. Using 13CO2-DNA-based stable isotope probing (SIP) coupled with metagenomics, we show that elevated temperatures associated with heatwave conditions restructure active nitrifying communities and their viruses in Yangtze River estuary tidal flats and adjacent agricultural soils. In tidal flats, high temperatures shifted active ammonia-oxidizing archaea and bacteria (AOA and AOB), and nitrite-oxidizing bacteria (NOB) from marine to terrestrial ecotypes. In contrast, heatwave conditions stimulated terrestrial ecotypes of AOA but suppressed AOB in agricultural soils. 13C-labeled nitrifier-infecting viruses also showed temperature-driven shifts in activity, lifestyle, and auxiliary metabolic genes in concert with hosts. Notably, AOA viruses carried the plastocyanin gene, potentially augmenting host metabolism. These findings demonstrate heatwaves drive complex shifts in nitrifier communities and their interactions with viruses, impacting global nutrient cycling under climate extremes.

microbiology↗

Numerical study of the size-based, shear-induced separation ofcirculating tumour cells from white blood cells in liquid biopsies

Circulating tumour cells (CTCs) are promising biomarkers for early cancer detection, yet their extreme rarity in blood necessitates efficient separation from white blood cells (WBCs) in lysed liquid biopsies. Inertial microfluidics offers a high-throughput, label-free approach to this challenge by leveraging size-dependent lateral migration. However, experimental observations reveal that WBCs migrate more rapidly than predicted, reducing separation performance. Using 3D lattice-Boltzmann-immersed-boundary-finite-element simulations, we characterized the migration dynamics of CTCs and WBCs in a straight microchannel. Our results reveal that the presence of a CTC enhances WBC cross-streamline migration, providing a mechanistic explanation for WBC contamination in CTC-enriched outlets. The numerical model capturing heterochiral orbital dynamics was validated experimentally, confirming the role of intercellular hydrodynamic interactions. These findings underscore the critical role of intercellular interactions in inertial microfluidic systems and provide guidance for optimizing suspension concentration and channel geometry to improve purity in rare cell isolation.

bioengineering↗

Chronic kidney disease exacerbates hyperlipidemia and atherosclerosis via miR-148a-3p targeting SIK1/AMPKα1 in liver

BackgroundCardiovascular complications are the leading cause of death in patients with chronic kidney disease (CKD). As a major risk factor for atherosclerotic cardiovascular disease (ASCVD), hyperlipidemia is a common sequela of CKD, which is linked to increased lipid synthesis, impaired lipoprotein clearance, and maladapted reverse cholesterol transport. Because exosomes can transport miRNAs to modulate intercellular and tissue communication, we hypothesized that exosomal miRNAs can act as endocrine-like molecules to modulate the CKD-associated hyperlipidemia and ASCVD. MethodsSmall RNA-seq and qPCR were used to determine the differential plasma level of exosomal miR-148a-3p in ASCVD patients with and without CKD. RNA-seq and in silico analysis were used to establish the regulation of lipid metabolism via miR-148a-3p/salt-inducible kinase 1 (SIK1)/AMP-activated protein kinase alpha 1 subunit (AMPK1) in the liver. Inhibition of miR-148a-3p or overexpression of SIK1/AMPK1 in ApoE-/- mice with 5/6 nephrectomy was used to elucidate the role of the miR-148a-3p/SIK1/AMPK1 axis in CKD-related hyperlipidemia and atherosclerosis. ResultsThe plasma level of exosomal miR-148a-3p was significantly elevated in patients with ASCVD and CKD (ASCVD/CKD) and ApoE-/- mice with 5/6 nephrectomy. Via circulating exosomes, kidney-generated miR-148a-3p was delivered to the liver, where it targeted SIK1/AMPK1 transcripts, thereby upregulating SREBP2/PCSK9 and reciprocally downregulating LDLR. Levels of SIK1 and AMPK1 were decreased in hepatocytes transfected with miR-148a-3p or treated with plasma exosomes from ASCVD/CKD patients, with attendant SREBP2 activation and attenuated LDL-C binding. The decreased LDL-C binding was rectified by SIK1/AMPK1 or LNA-miR-148a-3p overexpression. LNA-miR-148a-3p or AAV8-SIK1/AMPK administration in 5/6 nephrectomy/ApoE-/- mice significantly ameliorated hyperlipidemia and atherosclerosis. ConclusionIn ASCVD/CKD patients and nephrectomy/ApoE-/- mice, kidney-originating miR-148a-3p targeted hepatic SIK1/AMPK1 mRNA. This exosome-mediated endocrine effect upregulated SREBP2/PCSK9 and reciprocally reduced LDLR level, which elevated plasma LDL-C level and exacerbated ASCVD. These findings underscore a kidney-liver-artery axis involved in cardiovascular-kidney-metabolic syndrome.

pathology↗

Whole body MondoA deletion protects against diet-induced obesity through uncontrolled multi-organ substrate utilization and futile cycling

ObjectiveDelineating the nodal control points that maintain whole-body energy homeostasis is critical for understanding potential treatments of obesity and cardiometabolic diseases. The nutrient-sensing transcription factor MondoA is a regulator of skeletal muscle fuel storage, where muscle-specific inhibition improves glucose tolerance and insulin sensitivity. However, the role of MondoA in whole body energy metabolic homeostasis is not understood. MethodsGeneralized MondoA knockout (gKO) mice were generated and assessed for glucose tolerance and insulin sensitivity, body composition, energy expenditure, cold tolerance, and tissue specific transcriptional changes in response to high fat diet. Complementary studies in cultured human adipocytes assessed the impact of MondoA deficiency on substrate utilization and lipolysis. ResultsgKO mice are protected from diet-induced obesity and insulin resistance, through increased whole body energy expenditure. gKO mice exhibit reduced brown and inguinal white adipose tissue mass, without evidence of beiging. The gKO mice are hyperlactatemic and isolated MondoA-deficient adipocytes have increased 2-deoxyglucose uptake and glycolytic function. Lastly, gKO mice and KO adipocytes display increased circulating glycerol relative to free fatty acids in response to adrenergic stimulus consistent with elevated re-esterification. However, this phenotype is not recapitulated in adipocyte-specific KO mice. ConclusionsMondoA deficiency alters cellular sensing of nutrient availability and storage/utilization mechanisms. In the whole-body setting, this results in increased energy expenditure, potentially related to increased glucose uptake and glycolytic flux driving glycerol synthesis to supply high rates of lipolysis and lipid re-esterification. These results suggest that MondoA functions to maintain fuel storage and when lost, inter-organ futile cycling ensues. O_FIG O_LINKSMALLFIG WIDTH=140 HEIGHT=200 SRC="FIGDIR/small/680559v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@1ccf42dorg.highwire.dtl.DTLVardef@b2da28org.highwire.dtl.DTLVardef@1081aforg.highwire.dtl.DTLVardef@1b2168d_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract.C_FLOATNO 1) Global MondoA deficiency drives 2) tissue glucose uptake which in skeletal muscle is 3) converted and excreted as lactate, while in adipose tissue 4) triglyceride re-esterification requires 5) de novo glycerol synthesis to feed into the futile cycle. C_FIG

physiology↗

In Vivo Metabolic Tagging and Targeting of Circulating Red Blood Cells

Engineering red blood cells (RBCs) has been widely explored for drug delivery, imaging, vaccination, and other applications. However, effective strategies to directly engineer RBCs in vivo still do not exist. Here, for the first time, we report successful metabolic glycan labeling of RBCs in vivo. We demonstrate that systemically administered azido-sugars can metabolically label circulating RBCs with azido groups in the form of glycoproteins and glycolipids, with contributions from the labeling of both mature RBCs in the bloodstream and RBC precursor cells in the bone marrow. The RBC labeling efficiency can be improved by optimizing the choice and dose and dosing frequency of azido-sugars. The surface azido tags on RBCs can persist for >42 days in mice (nearly the lifespan of mouse RBCs), in sharp contrast to azido tags on leukocytes in the blood and cells in healthy tissues that decay to undetectable levels within 3 days. This in vivo RBC labeling technology does not induce any noticeable toxicity to RBCs, leukocytes, and healthy tissues. We further demonstrate that azido-labeled RBCs can covalently capture dibenzocyclooctyne-bearing cargos in vivo via click chemistry, prolonging the blood circulation of cargos from typical hours to >35 days. In a few examples, we show that the unprecedented RBC tagging and targeting technology can improve the fluorescence imaging of blood vessels and tumor tissues, enable long-term magnetic resonance imaging of brain vasculatures with one dose of gadolinium agent, and enhance the pharmacokinetics of drugs such as insulin.

bioengineering↗

Programmable Aptamer-Embedded Circular RNAs for Targeted Antigen-Presenting Cells Immunotherapy

The targeted delivery of mRNA to specific cell types in vivo remains a major unmet need in mRNA-based therapeutics. Conventional strategies rely on nanocarriers engineered with various modifications. However, these exogenous materials could cause adverse reactions, and their complex manufacturing processes often hinder clinical application. By leveraging the innate programmability of RNA sequences, we herein report a carrier-free, scalable, and programmable aptamer-embedded circular RNAs (Apt-circRNAs) design that confers targeting capability through the strategic incorporation of different aptamers at varying densities, while retaining circular RNA stability and protein production capability. Experimental results show that antigen-loaded Apt-circRNAs enable targeted delivery to antigen-presenting cells (APCs), drive endogenous antigen expression, activate antigen-specific T cells, and elicit potent immune responses that mediate clearance of both early-and late-stage tumors in mouse models. In humanized models of colorectal cancer, the combination of Apt-circRNA and PD-1 blockade produced synergistic antitumor effects and significantly reshaped the tumor microenvironment. In a first-in-human (FIH) clinical trial, Apt-circRNA vaccine encoding KRAS G12D/G12V neoantigens exhibited a favorable safety profile and induced robust immune activation, T cell mobilization, and neoantigen-specific immune responses. With this study, we have established a new paradigm in carrier-free, APC-targeted RNA vaccine design, offering a safe and effective platform for next-generation cancer immunotherapy.

bioengineering↗

Evolution of the rate, spectrum, and fitness effects of mutation under minimal selection in Caenorhabditis elegans

The rate, molecular spectrum, and fitness effects of mutations vary at all levels of the biological hierarchy, from within individual genomes to among taxonomic domains. Understanding the evolutionary factors underpinning that variation is of fundamental importance to biology. Accurate quantification of the properties of mutations requires that other evolutionary forces, especially natural selection, be minimized as much as possible. To investigate the evolution of the mutational process in C. elegans, we propagated a set of 100 "first order" mutation accumulation (O1MA) lines under minimal selection for [~]150 generations, divided each O1MA line into two "second order" MA (O2MA) lines and propagated them for another [~]150 generations, at which time the genome of each O2MA line was sequenced, and a subset of 50 O1MA families was assayed for competitive fitness. Over the course of the experiment, the mean nucleotide substitution mutation rate did not change, but the variance increased. In contrast, the indel mutation rate increased significantly. The two types of mutations fulfill the predictions of different theoretical models for the evolution of mutation rate. These results reinforce previous findings that the rate of indels is more sensitive to endogenous stress than the rate of nucleotide substitutions. Several evolutionary quandaries could be resolved if deleterious mutations interact synergistically (negative epistasis). Evidence for synergistic epistasis is famously inconclusive, although there is reason to think it may be more detectable under competitive conditions. However, a model of constant mutational effects on competitive fitness explains the results significantly better than a model including epistasis.

evolutionary biology↗