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Biology subjects

Qi, N.

Publications and source records attributed to Qi, N..

11 recordsLinked to original sources
bioRxiv2026

ComplexDesign: sequence-hallucination design of protein binders bridging multiple proteins

MotivationDesigning multichain protein complexes requires coordinating the folding of component proteins with the formation of their interfaces. The existing methods, however, remain limited in their ability to satisfy these requirements simultaneously, especially for trimeric and tetrameric complexes. As an important practical scenario, designing a binder that bridges two target proteins into a ternary complex requires flexibility in the relative arrangement of the two targets, adding an additional challenge to existing design methods. ResultsWe present ComplexDesign, a hallucination-based approach for multichain protein design. ComplexDesign performs structure-prediction-guided sequence optimization to simultaneously fold each protein chain and form inter-chain interactions that bind them together. To provide the flexibility required to appropriately arrange these target proteins, ComplexDesign introduces a specialized masking mechanism that enables exploration of possible relative arrangements rather than being limited to the predefined ones. Across a comprehensive set of benchmarks with various chain lengths, ComplexDesign outperformed existing methods in the unconditional design of dimers, trimers, and tetramers, achieving a high design success rate exceeding 50%, supporting its capability for multichain complex design. Furthermore, in the case of multi-target binder design, ComplexDesign produced high-confidence, self-consistent ternary complexes for 8 out of 10 target pairs. These results establish ComplexDesign as an effective tool for multichain protein design, with particular utility for designing binders that bridge two target proteins. Availability and implementationThe source code of ComplexDesign will be made publicly available upon publication.

bioinformatics↗
bioRxiv2026

WTAP-mediated epitranscriptomic program in alveolar macrophages confers prolonged protection against postinfluenza bacterial pneumonia

Secondary bacterial infections remain an intractable problem of seasonal influenza, primarily due to the depletion and defunctionalization of alveolar macrophages (AMs). Here, we described that N6-methyladenosine (m6A), the most prevalent RNA modification in eukaryotes, critically orchestrates trained immunity (TRIM) establishment in AMs. Influenza A virus (IAV)-trained AMs maintained low Wilms tumor 1-associated protein (WTAP) expression and reduced global m6A deposition for over two months. Mechanistically, this IAV-induced m6A decrease promotes TRIM by enhancing the RNA stability of phagocytic and metabolic genes, thereby boosting antibacterial function. Mimicking this m6A reduction pharmacologically or genetically recapitulates the IAV-trained TRIM phenotype, which improves phagocytosis and protects mice from secondary infection. Clinically, elevated WTAP in AMs correlates with impaired phagocytosis and disease severity in COVID-19 and COPD. These findings for the first time unveil how respiratory virus infection shapes AM TRIM via epitranscriptomic reprogramming, and offer prospective strategies for the prevention and treatment of post-viral bacterial complications.

immunology↗
bioRxiv2026

Engineered Lactate Catabolizing Probiotics Reveal Timescale Dependent Microbiome-Host Metabolic Coupling

The exchange of lactate, a metabolic substrate and regulator, between the gut lumen and systemic circulation for use in host and microbial processes is well documented, but tools capable of uncovering whether this process influences host metabolic status across acute and chronic contexts are lacking. In our prior work, we engineered probiotic Bacillus subtilis PY79 to produce lactate oxidase (LOX) intracellularly, allowing it to rapidly convert intestinal lactate to pyruvate. Following oral administration, LOX reduced systemic lactate concentrations at rest and under challenge conditions, providing a platform for investigating lactates influence on host metabolism and microbiota. In the present work, we demonstrate that acute LOX administration effectively rewired microbiota function and host energy balance, as revealed by 16S sequencing and indirect calorimetry. In silico microbial community modeling via MICOM and metagenomic inference via PICRUSt2 suggested that acute shunting of lactate to pyruvate induced microbiota remodeling towards anabolic processes, reflected by increased flux of pyruvate, acetate, and formate, alongside moderate to large increases (Cohens d = 0.60-1.00) in pathways for fructan degradation, B-vitamin biosynthesis, and lipid synthesis. These anabolic shifts temporally aligned with transient increases in host energy expenditure ({beta} = 1.08, p<0.05) via glucose oxidation ({beta} = 0.01, p<0.05), hinting at functional coupling between microbial biosynthesis and host energy balance via lactate exchange. Of note, acute LOX administration also improved thermoregulation and survival following LPS-induced sepsis, demonstrating functional relevance of these metabolic effects during acute inflammatory challenge. To assess chronic effects, we administered LOX for 6 weeks during diet-induced obesity. LOX treatment persistently reduced blood lactate. However, this chronic lactate reduction did not curtail the progression of diet-induced obesity or induce sustained modulation of host energy expenditure. This disconnect between acute and chronic findings suggests that gut-centric lactate conversion affects energy balance through microbiome and/or host-dependent mechanisms, but cannot override homeostatic forces in the long term to produce clinical benefit during chronic disease. Our results validate LOX probiotics as a tool for acute metabolic augmentation, and highlight a clear homeostatic limit to gut-centric therapies. This platform may enable targeted design of probiotic interventions matched to therapeutic timescale and inform synbiotic formulations that overcome homeostatic compensation.

microbiology↗
bioRxiv2026

Molecularly defined subpopulations of leptin receptor neurons dissociate the control of food intake from blood pressure

While previous studies have suggested that leptin regulates cardiovascular function independently of body weight, the specific leptin receptor (Lepr)-expressing neurons that mediate these distinct effects remain unknown. We found that genes located in blood pressure (BP)-associated genome-wide association study loci were regulated by leptin in Lepr and glucagon-like peptide-1 receptor (Glp1r)-expressing (LeprGlp1r) neurons. Ablating Lepr from these cells decreased BP despite causing hyperphagic obesity. Single-cell and spatial transcriptomics revealed that LeprGlp1r neurons segregate into two distinct subpopulations of cells located in the arcuate nucleus (ARC) and dorsomedial hypothalamic nucleus (DMH). Activating ARC LeprGlp1r neurons suppressed food intake without impacting energy expenditure or cardiovascular function. Conversely, DMH LeprGlp1r neurons increased energy utilization and BP without altering food intake. Our results identify distinct LeprGlp1r neuron subpopulations that dissociate the control of food intake from outputs related to sympathetic tone, including BP, suggesting the potential therapeutic utility of targeting of these subpopulations independently.

physiology↗
bioRxiv2024

Reciprocal links between methionine metabolism, DNA repair and therapy resistance in glioblastoma

Glioblastoma (GBM) is uniformly lethal due to profound treatment resistance. Altered cellular metabolism is a key mediator of GBM treatment resistance. Uptake of the essential sulfur-containing amino acid methionine is drastically elevated in GBMs compared to normal cells, however, it is not known how this methionine is utilized or whether it relates to GBM treatment resistance. Here, we find that radiation acutely increases the levels of methionine-related metabolites in a variety of treatment-resistant GBM models. Stable isotope tracing studies further revealed that radiation acutely activates methionine to S-adenosyl methionine (SAM) conversion through an active signaling event mediated by the kinases of the DNA damage response. In vivo tumor SAM synthesis increases after radiation, while normal brain SAM production remains unchanged, indicating a tumor- specific metabolic alteration to radiation. Pharmacological and dietary strategies to block methionine to SAM conversion slowed DNA damage response and increased cell death following radiation in vitro. Mechanistically, these effects are due to depletion of DNA repair proteins and are reversed by SAM supplementation. These effects are selective to GBMs lacking the methionine salvage enzyme methylthioadenosine phosphorylase. Pharmacological inhibition of SAM synthesis hindered tumor growth in flank and orthotopic in vivo GBM models when combined with radiation. By contrast, methionine depletion does not reduce tumor SAM levels and fails to radiosensitize intracranial models, indicating depleting SAM, as opposed to simply lowering methionine, is critical for hindering tumor growth in intracranial models of GBM. These results highlight a new signaling link between DNA damage and SAM synthesis and define the metabolic fates of methionine in GBM in vivo. Inhibiting radiation-induced SAM synthesis slows DNA repair and augments radiation efficacy in GBM. Using MAT2A inhibitors to deplete SAM may selectively overcome treatment resistance in GBMs with defective methionine salvage while sparing normal brain.

cancer biology↗
bioRxiv2021

A spatiotemporal steroidogenic regulatory network in human fetal adrenal glands and gonads

Human fetal adrenal glands produce substantial amounts of dehydroepiandrosterone (DHEA), which is one of the most important precursors of sex hormones. However, the underlying biological mechanism remains largely unknown. Herein, we sequenced human fetal adrenal glands and gonads from 7 to 14 GW via the 10x Genomics single-cell transcriptome techniques and reconstructed their location information by Spatial Transcriptome, conducted COOL-seq for the MC2R+ inner zone steroidogenic cells during the time window of sex differentiation (8-12GW). We found that relative to gonads, adrenal glands begin to synthesize steroids early. The coordination among steroidogenic cells and multiple nonsteroidogenic cells promotes adrenal cortex construction and steroid synthesis. Notably, during the time window of sex differentiation (8-12 GW), key enzyme gene expression shifts to accelerate DHEA synthesis in males and cortisol synthesis in females. Furthermore, high SST+ expressions in the adrenal gland and testis amplify androgen synthesis in males. Our research highlights the robustness of the action of fetal adrenal glands on gonads to modify the process of sexual differentiation.

systems biology↗
bioRxiv2019

Skeletal Muscle mTORC1 Activation Increases Energy Expenditure and Reduces Longevity in Mice

The mechanistic target of rapamycin (mTORC1) is a nutrient responsive protein kinase complex that helps co-ordinate anabolic processes across all tissues. There is evidence that signaling through mTORC1 in skeletal muscle may be a determinant of energy expenditure and aging and therefore components downstream of mTORC1 signaling may be potential targets for treating obesity and age-associated metabolic disease. Here, we generated mice with Ckmm-Cre driven ablation of Tsc1, which confers constitutive activation of mTORC1 in skeletal muscle and performed unbiased transcriptional analyses to identify pathways and candidate genes that may explain how skeletal muscle mTORC1 activity regulates energy balance and aging. Activation of skeletal muscle mTORC1 produced a striking resistance to diet-and age-induced obesity without inducing systemic insulin resistance. We found that increases in energy expenditure following a high fat diet were mTORC1-dependent and that elevated energy expenditure caused by ablation of Tsc1 coincided with the upregulation of skeletal muscle-specific thermogenic mechanisms that involve sarcolipin-driven futile cycling of Ca2+ through SERCA2. Additionally, we report that constitutive activation of mTORC1 in skeletal muscle reduces lifespan. These findings support the hypothesis that activation of mTORC1 and its downstream targets, specifically in skeletal muscle, may play a role in nutrient-dependent thermogenesis and aging.

physiology↗
bioRxiv2019

The calcium channel subunit α2δ-3 organizes synapses via a novel activity-dependent, autocrine BMP signaling pathway

Synapses are highly specialized for neurotransmitter signaling, yet activity-dependent growth factor release also plays critical roles at synapses. While efficient neurotransmitter signaling is known to rely on precise apposition of release sites and neurotransmitter receptors, molecular mechanisms enabling high-fidelity growth factor signaling within the synaptic microenvironment remain obscure. Here we show that the auxiliary calcium channel subunit 2{delta}-3 promotes the function of a novel activity-dependent autocrine BMP signaling pathway at the Drosophila NMJ. 2{delta} proteins have conserved synaptogenic activity, although how they execute this function has remained elusive. We find that 2{delta}-3 provides an extracellular scaffold for autocrine BMP signaling, suggesting a new mechanistic framework for understanding 2{delta}s conserved role in synapse organization. We further establish a transcriptional requirement for activity-dependent, autocrine BMP signaling in determining synapse density, structure, and function. We propose that activity-dependent, autocrine signals provide neurons with continuous feedback on their activity state and are thus well poised to modulate synapse structure and function.

neuroscience↗
bioRxiv2017

Glucocorticoid-Induced Metabolic Disturbances are Exacerbated in Obesity

Obesity and chronically elevated glucocorticoids result in similar co-morbidities, but the effect of a combination of these ailments on metabolic outcomes is unclear. Measures of glucose homeostasis and markers of hepatic lipid accumulation were assessed to determine whether obesity exaggerated the effects of dexamethasone-induced metabolic disturbances. The combination of obesity and glucocorticoids resulted in hepatic steatosis and synergistic impairments in insulin sensitivity and this was matched with synergistic elevations in markers of lipolysis. These findings suggest lipolysis may be a key player in glucocorticoid-induced insulin resistance and fatty liver in people with obesity.

physiology↗