Biology subjects

Zhao, R.

Publications and source records attributed to Zhao, R..

At least 55 records · Page 3Linked to original sources

bioRxiv2025

Hydration Network Drives Activation and G Protein Selectivity in GPR174

G protein-coupled receptor 174 (GPR174), a key modulator of autoimmune responses, maintains immune homeostasis through distinct G protein signaling pathways, particularly Gs and Gi. Although the structural mechanism of lysophosphatidylserine (LysoPS)-activated GPR174 in the Gs pathway has been characterized, how hydration-mediated interactions influence GPR174 activation and signaling selectivity remains unclear. Here, we determined high-resolution cryo-electron microscopy (cryo-EM) structures of LysoPS-activated GPR174 bound to Gs (2.0 [A]) and Gi (3.4 [A]), revealing a continuous hydration-mediated signaling transduction network that bridges the sodium-binding pocket, NPxxY and DRY motifs, and the G protein-binding interface. This network stabilizes the active-state conformation of GPR174 and dynamically reshapes the intracellular cavity, thereby enabling differential engagement of Gs and Gi. Molecular dynamics simulations and functional assays demonstrated that the hydration network is essential for receptor activation and selectively modulates G protein coupling. To evaluate its conservation, we performed sequence alignment and structural analysis across class A GPCRs, defining three hydration cavities: the conserved water cavity (CWC), the junction water cavity (JWC), and the extended water cavity (EWC), whose hydration is determined by residue properties at position 5.58. Together, our study reveals a hydration-driven molecular mechanism that underlies the activation of GPR174 and its dual G protein selectivity. These findings advance the understanding of hydration-mediated signaling in GPR174 and provide a framework for investigating water-mediated regulation across class A GPCRs.

biophysics↗

bioRxiv2025

A TP53 Intron-Derived Peptide Promotes Tumor Survival

During transcription, alternative cleavage and polyadenylation (APA) of transcripts produces mRNAs that differ in their 3 ends. We previously found that leukemia cells cleave and polyadenylate transcripts within introns (intronic APA, IPA) to generate truncated RNA isoforms, which perturb the expression and function of corresponding genes. In addition to protein-coding RNA, we found that leukemia cells express numerous putative long non-coding RNAs generated by IPA, with most uncharacterized. Here, we identify an IPA isoform encoded within intron 1 of the TP53 tumor suppressor gene that is translated into a non-canonical protein termed IPADP1 (IPA-derived protein 1). IPADP1 expression was detected in patient leukemia cells and human blood cancer cell lines. We uncovered an oncogenic role for IPADP1 in enhancing cancer cell survival during drug treatments, as well as promoting tumor formation in vivo. Using proteomic and functional studies, our data suggest that IPADP1 increases cell viability by regulating apoptotic signaling, cell cycle, and DNA damage responses. Furthermore, we observed that the expression of p53-IPA is significantly associated with SF3B1 mutations in leukemia patients, suggesting mechanisms for the genesis of this isoform. Our study demonstrates that an IPA isoform could have a function different from its host gene.

cancer biology↗

bioRxiv2025

U1 snRNP and RNA polymerase II interaction is predominantly mediated by Prp40 rather than U1-70K in yeast

Transcription and splicing are coupled both temporally and physically. A previous cryo-EM structure of the human U1 snRNP and RNA polymerase pol II complex has shown that U1 snRNP uses predominantly the RRM domain of U1-70K to directly interact with the RPB2 subunit of pol II. However, residues on U1-70K involved in the interaction with pol II are not conserved in yeast U1-70K, raising the question whether yeast U1 snRNP interacts with pol II in a similar manner. We found that yeast pol II associates with both U1 and U2 snRNPs, but U1-70K makes a minimal contribution to U1 snRNPs interaction with pol II. On the other hand, multiple domains of yeast Prp40 interact with pol II and the removal of the C-terminal domain (CTD) of pol II does not affect this interaction. Although yeast Prp40 is stably associated with U1 snRNP, its human homologs, PRPF40a and PRPF40b, are alternative splicing factors that are not integral components of U1 snRNP. This shift of function of Prp40 homologs may have led to the evolution of U1-70K to be the main interactor with pol II in the human system.

biochemistry↗

bioRxiv2025

Modeling 3D Mesoscaled Neuronal Complexity through Learning-based Dynamic Morphometric Convolution

Accurate reconstruction of neuronal morphology from three-dimensional (3D) light microscopy is fundamental to neuroscience. Nevertheless, neuronal arbors intrinsically exhibit slender, tortuous geometries with high orientation variability, posing significant challenges for standard 3D convolutions whose static, axis-aligned receptive fields lack adaptability to such complex morphology. To address this, we propose the Dynamic Morph-Aware Convolution (DMAC) framework, which incorporates inherent geometric priors into convolution by jointly adapting both the shape and orientation of the kernel. This enables morphology-aware feature extraction tailored to arborized and variably oriented neuronal trajectories. Specifically, we first apply dynamic tubular convolutions to bridge the structural mismatch between isotropic convolution kernels and the slender morphology of neurons. To sufficiently accommodate the 3D orientation variability of neuronal branches, we further introduce a rotation mechanism that dynamically reorients the tubular kernel via two learnable angles (elevation and azimuth), enabling precise alignment with local neuronal directions. We validate our method through extensive experiments on four mesoscaled neuronal imaging datasets, including two from the BigNeuron project (Drosophila and Mouse) and two additional benchmarks (NeuroFly and CWMBS). Our approach consistently outperforms state-of-the-art methods, achieving average improvements of 5.4% in Entire Structure Average (ESA), 6.9% in Different Structure Average (DSA), and 7.5% in Percentage of Different Structure (PDS). These results demonstrate the effectiveness of our proposed DMAC in capturing complex morphological variations and enhancing structural fidelity across diverse mesoscaled neuronal morphologies.

neuroscience↗

bioRxiv2025

The U1 snRNP protein U1C and Helix H of U1 snRNA are critical for small molecule splicing modulator function

Risdiplam and branaplam represent two classes of small-molecule splicing modulators that promote U1 snRNP recognition of weak non-canonical GA/GU-containing 5 splice sites (ss). We demonstrated that branaplam enhanced recognition of these 5 ss by reconstituted U1 snRNP in vitro, and that this effect depended on the ZnF domain of U1C and Helix H of U1 snRNA, but not U1A or U1-70K. In cells, depletion of U1C generally reduced compound-induced exon inclusion for most cassette exons. Interestingly, a subset of cassette exons became responsive to compound only upon U1C knockdown, supporting a model in which U1C stabilizes specific conformations at the 5 ss/U1 snRNA interface in a context-dependent manner that can either facilitate or hinder compound binding. Surprisingly, risdiplam shows no effect on weak 5 ss recognition in vitro, suggesting additional cellular factors are required for its activity.

biochemistry↗

bioRxiv2025

Comparison of the 2-CT method and the 2-ΔΔCT method for real-time qPCR data analysis

[purpose]The [Formula] method proposed by Livak and Schmittgen in 2001 is used for real-time quantitative polymerase chain reaction (RT-qPCR) data analysis. This methods fundamental logic involves normalizing all data against the control group to achieve relative quantification of gene expression. During our practical calculations, we identified an inherent bias in this method: the practice of directly taking arithmetic means of a set of C (or {Delta}C) values during [Formula] calculations fails to fully account for the exponential nature of CT values (where CT values serve as exponents in power-of-2 operations), leading to deviations in computational results. In this study, we elucidate this systematic bias and propose an innovative approach to circumvent it. [Methods]We propose the [Formula] method, which bases calculations on [Formula] values and computes the fold-change of target genes relative to control group target genes. The computational logic of the [Formula] method strictly adheres to the exponential characteristics of CT values, avoiding the use of arithmetic averaging at CT and {Delta}CT levels, thereby more accurately reflecting gene expression levels in datasets. In this paper, we detail the computational process of the [Formula] method and compare results from both methodologies. [Results]Calculations based on Livak and Schmittgens published data show differences between the two methods, though the discrepancies are relatively small. In calculations from our recent cadmium exposure experiments, the [Formula] method indicates that 8-hour cadmium exposure increases irg-6 gene expression in C. elegans from 1.314 to 7.125-fold, while the [Formula] method shows an increase from 1 to 4.124-fold. The two methods exhibit nearly 70% discrepancy in irg-6 gene fold-change quantification, with statistical p-values of 0.0002 and 0.0015 respectively. In all calculations presented in the paper, the [Formula] method fails to produce an exact unit value (mean fold-change = 1) for control groups, whereas the [Formula] method consistently yields control group results of exactly 1, demonstrating its capability for precise normalization. [Conclusions]In summary, the [Formula] method demonstrates superior computational rigor, and we recommend its adoption in RT-qPCR data analysis. This improvement proves particularly valuable for experimental datasets with substantial CT value variability among different samples, establishing a more reliable computational paradigm for RT-qPCR analysis.

molecular biology↗

bioRxiv2025

Effect of Caenorhabditis elegans U6 Promoters on CRISPR/Cas9-Mediated Gene Editing Efficiency

ObjectiveThis study investigated the effects of endogenous C. elegans U6 promoters on dpy-10 gene editing efficiency. MethodsWe screened endogenous U6 snRNA genes from the WormBase database and constructed 14 editing plasmids targeting dpy-10 by replacing the U6r07e5.16 promoter in pSX524 (Peft-3::cas9::tbb-2 terminator::U6 r07e5.16::dpy-10 sgRNA) through molecular cloning. Following standardized microinjection protocols, we quantified gene editing efficiency and high-efficiency gene editing index based on dpy-10 mutant phenotypes in F1 progeny. ResultsFifteen U6 snRNA genes (r07e5.16, f35c11.9, t20d3.13, k09b11.15, k09b11.16, w05b2.8, c28a5.7, f54c8.9, k09b11.11, k09b11.12, k09b11.14, t20d3.12, f54c8.8, f54c8.10, k09b11.13) were identified from WormBase database. Comparative analysis revealed four U6 promoters (w05b2.8, c28a5.7, f54c8.9, and k09b11.11) significantly enhanced gene editing compared to other U6 promoters, including commonly used U6r07e5.16 and U6k09b11.12 promoters in C. elegans community. Notably, the gRNAF+E scaffold showed no improvement over the gRNA scaffold when paired with the optimal U6w05b2.8 promoter. ConclusionThis study identifies superior U6 promoters for C. elegans gene editing and demonstrates the critical role of promoter optimization in CRISPR systems, providing novel insights for technical refinement.

molecular biology↗

bioRxiv2025

A survey of dietary effects on tRNA abundance and modifications

Transfer RNAs (tRNAs) play a central role in protein translation and are increasingly recognized as dynamic regulators of gene expression. Both physiological and environmental signals can modulate tRNA abundance and chemical modifications, yet the impact of dietary cues on the tRNA landscape remains poorly understood. Here, we investigated the effects of two distinct dietary interventions--low-protein and high-fat diets--on tRNA abundance and modification profiles across multiple mouse tissues. We conducted a comprehensive analysis of tRNA abundance and modification changes in response to these nutritional challenges using RNA mass spectrometry and Ordered Two-Template Relay sequencing (OTTR-seq), a modified-base-sensitive tRNA sequencing method. Our results reveal both shared and tissue-specific alterations in abundance and modifications of specific nuclear and mitochondrial genome-encoded tRNAs in response to dietary conditions at isotype, isoacceptor, and isodecoder levels. As many of the tissue-specific or diet-responsive tRNA modifications have been previously reported to affect decoding efficiency or translational fidelity, these results have implications for understanding translational adaptation in response to dietary conditions.

genomics↗

bioRxiv2025

Altered susceptibility of rare yeast species causing vulvovaginal candidiasis at acidic vaginal environment

This study evaluated potency of antifungals against the rare emerging yeast causing VVC under the influence of acid pH (4.5). The antifungal susceptibility was evaluated by CLSI-M27A4 for 25 isolates represented 11 rare yeast species recovered from VVC patients. Among 11 yeast species (25 isolates), Clavispora lusitaniae (n=9) was the most common species, followed by Cyberlindnera fabianii (n=4), Kodamaea ohmeri, Candida metapsilosis and Candida bracarensis (n=2, respectively), Pichia norvegensis, Kluyveromyces marxianus, Diutina rugosa, Tricholoma matsutake, Candida nivariensis and Candida africana (n=1, respectively). The antifungal agents most affected by a lower pH were terconazole (4-fold higher, MIC >0.5-8mg/L) to all 11 yeast species; followed by amphotericin B (3-fold higher, MIC >2mg/L) to 9 species except K. ohmeri and D. rugose; nystatin (2-fold higher, MIC >2 - 4 mg/L) to 9 species except C. nivariensis and C.africana; micafungin (2-fold higher, MIC >0.125 - 1 mg/L) to 8 species except C. metapsilosis, D. rugosa and Tricholoma matsutake by acid pH, respectively. 5-flucytosine was not affected by pH to all tested yeast species, and maintained activity at low PH. The rare yeast species tested shared high MICs of terconazole, amphotericin B, nystatin at pH4.5 compared with those at pH7.0. The in vitro antifungal susceptibility at pH 7.0 did not consistently predict the activity of antifungals against those rare yeast species at vaginal acidic pH. Further investigations assessing the clinical utility of antifungal susceptibility testing should take these findings into consideration.

microbiology↗

bioRxiv2025

eIF3d and eIF3e mediate selective translational control of hypoxia that can be inhibited by novel small molecules

Exposure to hypoxia is linked to increased cellular plasticity and enhanced metastasis; effects which are primarily attributed to the transcriptional activation of large gene programs downstream of hypoxia inducible factors (HIFs). However, translational effects in hypoxia, that likely precede transcriptional effects, have remained largely unexplored. Using ribosome-profiling, we uncovered a selective translational response in acute hypoxia that is eIF3d/eIF3e-dependent and controls downstream hypoxic responses including HIF1a accumulation and cellular invasion. We further demonstrated that eIF3e copy number and an eIF3e-expression signature are associated with worsened outcomes for breast cancer patients. Finally, we identified a class of novel small molecules that target eIF3e specifically, reducing the translational response to hypoxia and to ER stress, another stressor that is dependent on eIF3d/eIF3e-mediated translation. Our data uncover critical functions for eIF3d/eIF3e in the hypoxic response and identify a potential means to inhibit stress-induced translation, and potentially plasticity and metastasis, mediated by eIF3e.

cancer biology↗

bioRxiv2025

DNA2 and FANCM function in two distinctive pathways in disrupting TERRA R-loops and suppressing replication stress at ALT telomeres

Cancers maintain their telomeres through two main telomere maintenance mechanisms (TMMs): 85-90% of cancers rely on telomerase, while 10-15% of cancers adopt the Alternative Lengthening of Telomere (ALT) pathway. Previously, we and others reported that FANCM, one of the Fanconi Anemia proteins, plays a critical role in suppressing replication stress and DNA damage at ALT telomeres by actively disrupting TERRA R-loops [1-4]. Here, we showed that inactivation of DNA2 in ALT-positive (ALT+) cells, but not in telomerase-positive (TEL+) cells, induces a robust increase of replication stress and DNA damage at telomeres, which leads to a pronounced increase of many ALT properties, including telomere dysfunction-induced foci (TIFs), ALT-associated PML bodies (APBs), and C-circles. We further demonstrated that depletion of DNA2 induces a pronounced increase of TERRA R-loops and a decrease in replication efficiency at ALT telomeres. Most importantly, we uncovered a strong additive genetic interaction between DNA2 and FANCM in the ALT pathway. Furthermore, co-depletion of DNA2 and FANCM causes synthetic lethality in ALT+ cells, but not in TEL+ cells, suggesting that targeting DNA2 and FANCM could be a viable strategy to treat ALT+ cancers. Finally, utilizing the single-molecule telomere assay via optical mapping (SMTA-OM) technology, we thoroughly characterized genome-wide changes in DNA2 deficient cells and FANCM deficient cells and found that most chromosome arms manifested increased telomere length. Unexpectedly, we uncovered many chromosome arm-specific telomere changes in those cells, suggesting that telomeres at different chromosome arms may regulate and respond to replication stress differently. Collectively, our study not only shed new light on the molecular mechanisms of the ALT pathway, but also discovered a new strategy for targeting ALT+ cancer.

cancer biology↗

bioRxiv2025

Humans underestimate their body mass in microgravity: evidence from reaching movements during spaceflight

Astronauts consistently exhibit slower movements in microgravity, even during tasks requiring rapid responses. The sensorimotor mechanisms underlying this general slowing remain debated. Two hypotheses have been proposed: either the sensorimotor system adopts a conservative control strategy for safety and postural stability, or the system underestimates body mass due to reduced inputs from proprioceptive receptors. To dissociate these opinions, we studied twelve taikonauts aboard the China Space Station performing a classical hand-reaching task. Compared to their pre-flight performance and to an age-matched control group, participants showed increased movement durations and altered kinematic profiles in microgravity. Model-based analyses of motor control parameters revealed that these changes stemmed from reduced initial force generation in the feedforward control phase followed by compensatory feedback-based corrections. These findings providing support for the body mass underestimation hypothesis while being inconsistent with the strategic slowing hypothesis. Importantly, the sensory estimate of bodily property in microgravity is biased but immune from sensorimotor adaptation, calling for an extension of existing theories of motor learning.

neuroscience↗

bioRxiv2025

Neural sampling from cognitive maps supportsgoal-directed planning and imagination

AI systems are becoming more intelligent, but at a very high cost in terms of energy consumption and training requirements. In contrast, our brains only require 20W of energy, they learn online, and they can instantly adjust to changing contingencies. This begs the question what data structures, algorithms, and learning methods enable brains to achieve that, and whether these can be ported into artificial devices. We are addressing this question for a core feature of intelligence: The capacity to plan and solve problems, including new problems that involve states which were never encountered before. We examine three tools that brains are likely to employ for achieving that: Cognitive maps, stochastic computing, and compositional coding. We integrate these tools into a transparent neural network model, and demonstrate its power for flexible planning and problem solving. Importantly, this approach is suitable for implementation by in-memory computing and other energy-efficient neuromorphic hardware. In particular, it only requires self-supervised local synaptic plasticity that is suited for on-chip learning. Hence a core feature of brain intelligence, the capacity to generate solutions to problems that were never encountered before, does not require deep neural networks or large language models, and can be implemented in energy-efficient edge devices.

neuroscience↗

bioRxiv2025

Aging-dependent dysregulation of EXOSC2 is maintained in cancer as a dependency

Reprogramming of aged donor tissue cells into induced pluripotent stem cells (A-iPSC) preserved the epigenetic memory of aged-donor tissue, defined as genomic instability and poor tissue differentiation in our previous study. The unbalanced expression of RNA exosome subunits affects the RNA degradation complex function and is associated with geriatric diseases including premature aging and cancer progression. We hypothesized that the age-dependent progressive subtle dysregulation of EXOSC2 (exosome component 2) causes the aging traits (abnormal cell cycle and poor tissue differentiation). We used embryonic stem cells as a tool to study EXOSC2 function as the aging trait epigenetic memory determined in A-iPSC because these aging traits could not be studied in senesced aged cells or immortalized cancer cells. We found that the regulatory subunit of PP2A phosphatase, PPP2R5E, is a key target of EXOSC2 and this regulation is preserved in stem cells and cancer.

cell biology↗

bioRxiv2025

The mechanism how Pretubulysin-induced microtubule disassembly improves T cell search efficiency

To clean tissue from tumorigenic and infected cells, cytotoxic T lymphocytes (CTLs) must navigate confined environments in vivo, locate the infected cells and eliminate them. Impaired CTL migration towards the tumor can limit the efficacy of immunotherapy. Microtubules (MTs) have emerged as promising targets, because destabilizing MTs enhances T-cell migration and subsequent killing, yet the underlying mechanisms are poorly understood. Here, we use pretubulysin, a potent MT depolymerizer, to uncover how MT dynamics regulate CTL motility. Complete MT disassembly markedly increased CTL infiltration and migration in 3D matrices. To investigate how altered migration affects target elimination, we employed a persistent random-walk model parameterized solely with experimental motility data. The model shows that the increase in speed and persistence induced by pretubulysin explains enhanced search efficiency increasing the encounter rate of CTLs with target cells. The simulations also predict how these gains in search efficiency scale with tissue thickness and CTL density. Mechanistically, MT depolymerization in activated CTLs triggers localized actomyosin accumulation at the uropod. This enhances rear contraction forces and promotes faster, more persistent migration and efficient search. Our findings clarify how MT dynamics influence CTL ability to eliminate targets in 3D environments and highlights the potential of MT-targeting agents such as pretubulysin to optimize T cell-based immunotherapies.

cell biology↗

bioRxiv2025

Leveraging long-read assemblies and machine learning to enhance short-read transposable element detection and genotyping

Transposable elements (TEs) are parasitic genomic elements that are ubiquitous across the tree of life and play a crucial role in genome evolution. Advances in long-read sequencing have allowed highly accurate TE detection, though at a higher cost than short-read sequencing. Recent studies using long reads have shown that existing short-read TE detection methods perform inadequately when applied to real data. In this study, we use a machine learning approach (called TEforest) to discover and genotype TE insertions and deletions with short-read data by using TEs detected from long-read genome assemblies as training data. Our method first uses a highly sensitive algorithm to discover potential TE insertion or deletion sites in the genome, extracting relevant features from short-read alignments. To discriminate between true and false TE insertions, we train a random forest model with a labeled ground-truth dataset for which we have calculated the same set of short-read features. We conduct a comprehensive benchmark of TEforest and traditional TE detection methods using real data, finding that TEforest identifies more true positives and fewer false positives across datasets with different read lengths and coverages, while also accurately inferring genotypes and the precise breakpoints of insertions. By learning short-read signatures of TEs previously only discoverable using long reads, our approach bridges the gap between large-scale population genetic studies and the accuracy of long-read assemblies. This work provides a user-friendly tool to study the prevalence and phenotypic effects of TE insertions across the genome.

genomics↗

bioRxiv2025

Cryo-EM structures reveal the PP2A-B55α and Eya3 interaction that can be disrupted by a peptide inhibitor

We have previously shown that Eya3 recruits PP2A-B55 to dephosphorylate pT58 on Myc, increasing Myc stability and enhancing primary tumor growth of triple-negative breast cancer (TNBC). However, the molecular details of how Eya3 recruits PP2A-B55 remain unclear. Here we determined the cryo-EM structures of PP2A-B55 bound with Eya3, with an inhibitory peptide B55i, and in its unbound state. These studies demonstrate that Eya3 binds B55 through an extended peptide in the NTD of Eya3. The Eya3 peptide and other PP2A-B55 substrates and protein/peptide inhibitors including B55i bind to a similar area on the B55 surface but the molecular details of the binding differ. We further demonstrated that the B55i peptide inhibits the B55 and Eya3 interaction in vitro. B55i peptide expressed on a plasmid increases pT58 and decreases Myc protein level in TNBC cells, suggesting the potential of B55i or similar peptides as therapies for TNBC.

molecular biology↗

bioRxiv2025

Telomeric SUMO level influences the choices of APB formation pathways and ALT efficiency

Many cancers use an alternative lengthening of telomeres (ALT) pathway for telomere maintenance. ALT telomeric DNA synthesis occurs in ALT telomere-associated PML bodies (APBs). However, the mechanisms by which APBs form are not well understood. Here, we monitored the formation of APBs with time-lapse imaging employing CRISPR knock-in to track the promyelocytic leukemia (PML) protein at endogenous levels. We found APBs form via two pathways: telomeres recruit PML proteins to nucleate PML bodies de novo, or telomeres fuse with preformed PML bodies. Both nucleation and fusion of APBs require interactions between SUMO and SUMO interaction motifs (SIMs). Moreover, APB nucleation is associated with higher levels of SUMOs and SUMO-mediated recruitment of DNA helicase BLM, resulting in more robust telomeric DNA synthesis. Finally, further boosting SUMO levels at telomeres enhances APB nucleation, BLM enrichment, and telomeric DNA synthesis. Thus, high SUMO levels at telomeres promote APB formation via nucleation, resulting in stronger ALT activity.

cell biology↗