Biology subjects

Su, X.

Publications and source records attributed to Su, X..

At least 19 recordsLinked to original sources

bioRxiv2026

Vascularized Organoids Emerge from a Heart-Foregut-like Intermediate Recapitulating Early Human Development

During early cardiogenesis, the heart regions lie in close contact with foregut endoderm, which supplies essential nutrients and signaling cues to orchestrate primitive heart tube assembly. Here, we show that self-organized heart/foregut like-structures emerge from human pluripotent stem cells (hPSCs). The initial heart/foregut-like structures, termed the Seed, are encased by surrounding supportive cells termed Soil, which provide a matrix microenvironment; the Seed progressively develops into chambered human cardiac organoids (hCOs) containing cardiomyocytes (CMs), epicardial cells, cardiac fibroblasts, and endothelial cells. Optimization of the induction system further enhanced hCO maturation and vascularization. Therefore, this Soil-Seed system provides a model to dissect human early heart/foregut self-organization.

developmental biology↗

bioRxiv2026

Impacts of different SETD1A mutations and genetic backgrounds on human induced pluripotent stem cell-derived hippocampal neurons

Abstract Human induced pluripotent stem cells (hiPSCs) provide a translational platform to interrogate the impact of genetic risk factors for various disorders on human biology. It has been a common practice to engineer premature stop codons to model predicted loss-of-function mutations using isogenic hiPSCs, yet effects of mutation position for the same gene and genetic background have been rarely tested systematically and at multiple levels for comparison to those of patient-specific mutations. Ultra-rare, heterozygous, and predicted loss-of-function mutations in the SETD1A gene, which encodes a H3K4 methyltransferase, are highly penetrant genetic risk factors for schizophrenia. Here, we generated a large panel of isogenic heterozygous SETD1A mutant hiPSC lines, including premature stop-codon mutations in one early exon and one late exon in five genetic backgrounds and two patient-specific mutations, to gain insight into molecular, cellular, and functional changes in a disease-relevant and highly pure population of human hippocampal dentate granule cell-like neurons. Our multi-level analyses showed that different SETD1A mutations lead to divergent molecular and cellular phenotypes related to synapses, but convergent neuronal network deficits, while the genetic background influences gene expression with no substantial effects at cellular and network levels. Mechanistic analysis confirmed the early exon patient mutation as loss-of-function, but revealed that the predicted loss-of-function patient mutation in the late exon is likely gain-of-function. Consequently, while all mutations decreased global H3K4me3 levels, deficits were only partially rescued by inhibiting H3K4 demethylase LSD1 for early exon mutations, but not for late exon mutations. Together, these results suggest that highly penetrant mutations can lead to similar cellular and functional phenotypes across different genetic backgrounds, whereas different premature stop-codon mutations could have contrasting impacts due to distinct mechanisms. Our findings have practical implications for applying genome-editing in hiPSCs to model disorders, highlight the value of modeling patient-specific mutations and testing multiple mutations, and suggest the need for tailored mutation-dependent therapeutic strategies.

neuroscience↗

bioRxiv2026

Sequence-specific and programmable catalytic degradation of extracellular microRNAs by membrane-anchored DNA nanomachines

Extracellular microRNAs (miRNAs) contribute to metastasis through communication between tumour cells and their microenvironment, yet their sustained, sequence-selective depletion remains challenging. Here we report Programmable RNA-Intercepting Molecular Eraser (PRIME), a membrane-anchored DNA nanomachine that organizes miRNA recognition and catalytic degradation at the cell surface. A double-tetrahedral DNA scaffold positions a programmable recognition hairpin beside RNase H. Target binding generates an RNA/DNA hybrid for RNase H-mediated cleavage, and product release resets the hairpin for subsequent degradation cycles. Membrane-anchored PRIME depleted matched extracellular miRNAs by 70.6-89.4% across lung, breast and cervical cancer cell models. Multi-target PRIME (M-PRIME) inhibited migration by 71.3-96.0% in Transwell assays across these models. To evaluate its therapeutic potential, we established an orthotopic lung-tumour model and an early-intervention breast-cancer lung-colonization model in mice. Aptamer-directed M-PRIME combined with gemcitabine reduced pulmonary tumour burden by 74.5% in established lung tumours and 93.2% in the lung-colonization model. These effects were consistent with PRIME-mediated extracellular miRNA degradation, with circulating target miRNA levels reduced by 77.5-98.7% relative to gemcitabine alone. Together, these findings establish a programmable material strategy for sustained extracellular RNA depletion and support its potential to enhance chemotherapy in preclinical tumour models.

biochemistry↗

bioRxiv2026

Hypomagnetic field inhibits seed germination via ROS signaling and reprogramming transcriptome in Arabidopsis thaliana

The geomagnetic field (GMF) is a ubiquitous yet poorly understood environmental factor that affects plant growth and development. It has been suggested that the blue-light photoreceptor cryptochrome (CRY) functions as a critical magnetic-field sensor in birds and insects through the radical-pair mechanism (RPM). However, whether CRY acts as a bona fide transducer of GMF signals and what are the downstream cascades remain largely elusive in plants. To address these key issues, we generated hypomagnetic field (HMF) via Helmholtz coils and passive magnetic shielding to investigate the GMF deprivation effects in Arabidopsis thaliana. HMF significantly delays the germination speed without altering the final germination rate, suggesting that HMF specifically modulates germination kinetics rather than seed viability. Time-resolved transcriptomic profiling revealed a coordinated transcriptional shift characterized by downregulation of growth-promoting genes and concurrent upregulation of defense-related genes under HMF. This biphasic transcriptional reprogramming coincides with a significant increase of reactive oxygen species (ROS), linking redox perturbation to the germination delay. Consistently, supplementation with ROS-scavenging antioxidants (e.g., reduced glutathione and ascorbic acid) rescues both germination speed and the misregulated expression of a subset of HMF-responsive genes, suggesting the central role of ROS in mediating HMF bioeffects. Genetic analysis using cry1 cry2 double mutants further indicated that HMF-induced germination delay operates through both CRY-dependent and -independent signaling pathways, suggesting the involvement of additional magnetosensitive modules beyond the canonical CRY-based RPM. These findings suggest that the GMF acts as a positive environmental cue that fine tunes the growth-defense trade-off through a redox-dependent signaling.

plant biology↗

bioRxiv2026

Curved by Design: Applying Microfluidic Principles for Nonplanar and Planar Suspended Tissue Patterning to the Development of Bladder Models with Tunable Mechanics

Cells in vivo exist in a complex environment where they receive chemical and physical cues from neighboring cells and the extracellular matrix. Suspended, three dimensional (3D) cell culture enables the study of mechanical signals in a controlled in vitro setting where cells can exert forces on the extracellular matrix, and mechanical stimulation can be externally applied. In addition to mechanical cues, tissues in vivo also exhibit spatial heterogeneity and nonplanar topography. To facilitate the development of suspended 3D cell culture models with both spatial and geometric complexity, we previously introduced Suspended Tissue Engineering with Assemblable Microfluidics (STEAM). STEAM is an accessible, modular platform that utilizes fluidic patterning to create multiregional planar and nonplanar suspended cell-embedded 3D tissues. Herein, we further characterize the STEAM dome platform by developing a theoretical model that explains some experimental considerations necessary for successful two-region patterning in a nonplanar construct. We highlight a brief biological application of the planar and nonplanar STEAM platforms by creating simple but physiologically relevant model systems for the bladder, a sphere-like organ with concentric tissue layers and a central lumen that dynamically expands and contracts during filling and voiding. We demonstrate that the suspended configuration of the planar bladder smooth muscle tissue patch induces inherent tension, which can be increased by further straining the tissues; both result in muscle cell alignment along the axis of stretch as shown by a clear peak at 90 degrees in a radial sum analysis of the two dimensional Fast Fourier Transform of images with fluorescent signal from myosin heavy chain 11 immunostaining. Further, we utilize the nonplanar STEAM platform with a human urothelial cell line (HBLAK) and primary bladder smooth muscle cells (HBdSMC) to create a bladder wall model, resulting in a domed, bilayered tissue. STEAM integrates patterning precision, mechanical functionality, and customizability to actualize an accessible and low cost alternative to generate spatially and geometrically complex suspended tissues.

bioengineering↗

bioRxiv2026

Multi-Omics analysis provides crucial insights into ecological adaptation to dryland of a dominant grass (Psammochloa villosa, Poaceae) in Northwest China

Desertification exerts dramatic selection pressures on the evolution of plants. Despite the key role of ecological adaptation by natural selection to arid grasslands and subsequent intraspecific divergence, specific mechanisms driving this process remain poorly understood. Psammochloa villosa, a perennial forage grass endemic to the arid grasslands in Northwest China, where it thrives in shifting and semi-fixed sand land due to its exceptional drought tolerance, provides an ideal system to study adaptive evolution to aridity. In our study, we assembled a high-quality, chromosome-scale genome and conducted genomic resequencing of 42 populations across its major distribution. The genome assembly, which is approximately 1.55 Gb in size, has a super-scaffold N50 of 66.79 Mb, with 75.84% of the sequences identified as transposable elements. Coalescent phylogeny and genomic collinearity analyses strongly supported that P. villosa and Neotrinia splendens, as the closest taxa, shared a recent whole-genome duplication (WGD) event occurring approximately 18-20 Mya and followed by their divergence around ~11.2 Mya. Based on ancestral grass karyotype (AGK) reconstruction from synteny analysis, our results suggest that, relative to the AGK after the {rho}-WGD event, P. villosa and N. splendens underwent similar chromosomal restructuring and lineage-specific retention of numerous copies, providing a genomic basis for potential ecological adaptation and intraspecific diversification. The expanded XTH family, which encodes enzymes mediating xyloglucan endotransglucosylation and hydrolysis and thereby regulating xyloglucan remodeling, showed strong transcriptional responses under PEG-6000 treatment, suggesting that retained copies may be associated with xerophytic adaptation in P. villosa. Together, these findings suggest that WGD-derived gene retention created a delayed reservoir of genetic diversity that was later shaped by desertification and Qinghai-Xizang Plateau environmental changes, contributing to climate-associated genomic islands and intraspecific differentiation.

genomics↗

bioRxiv2026

Programmable Recruitment of RNA-Binding Proteins Enables Small Molecule-Directed Destabilization of Nuclear Pre-mRNA

Chemically induced proximity has not been systematically applied to control RNA fate. Here, a programmable platform was developed to identify RNA-binding proteins (RBPs) that can be recruited by small molecules to destabilize RNA. Using microtubule-associated protein Tau (MAPT) pre-mRNA as a model target, a heterobifunctional molecule was designed to bind both a ligandable structure in MAPT pre-mRNA and FKBP12F36V-tagged RBPs. Screening of a library of tagged RBPs identified several proteins that reduced MAPT RNA levels, including zinc finger protein 36 (ZFP36) and nanos C2HC-type zinc finger 3 (NANOS3). The approach was then extended from engineered proteins to an endogenous RBP. Using small molecule ligandability maps, a cysteine-reactive ligand for ZFP36 was identified. When this ligand was linked to the MAPT-binding small molecule, endogenous ZFP36 was recruited to MAPT mRNA, reducing its abundance in cells. Genetic and chemical controls demonstrated that activity was dependent on both RNA binding and ZFP36 recruitment, supporting an induced-proximity mechanism. These studies establish a general strategy for identifying new recruitable RBP effectors and should advance ribonuclease-targeting chimera (RiboTAC) technology by expanding the repertoire of effector proteins that can be harnessed for RNA degradation. More broadly, new effectors can be discovered through model reporter-based screens and translated to endogenous systems by mining known protein binders and ligandability maps, providing a systematic path to develop small molecules that control RNA stability, including RNAs targeted through structured regions of nuclear pre-mRNAs.

biochemistry↗

bioRxiv2026

Potato Agent: AI-Driven Data and Knowledge Exploration on an Agent-Ready Potato Multi-Omics Platform

Potato is an important non-cereal food crop worldwide. However, the limited number of functionally validated genes remains a major bottleneck to favorable allele stacking and genome design breeding in potato. Rapid advances in AI agents offer a promising means to support crop breeding by translating natural-language questions into coordinated data analysis and knowledge retrieval. Their reliable use for potato breeding, however, is constrained by fragmented multi-omics resources that lack consistent curation and machine-accessible interfaces. Here, we constructed an agent-ready potato multi-omics database integrating genomic resources from 150 potato accessions, 259 bulk RNA-seq samples, and 14 spatial transcriptomic datasets into a pangenome, a tissue expression atlas, co-expression networks, and spatial expression maps accessible through open APIs. We developed 39 potato-specific Agent Skills for reproducible bioinformatics analysis and comprehensive data and knowledge exploration, enabling natural-language questions to be translated into standardized data-retrieval and analysis tasks. By integrating direct evidence from potato studies, functions of homologous genes in Arabidopsis, rice, and maize, and tissue expression patterns, we generated genome-wide functional predictions for 37,658 genes in the DM reference genome. We further developed Potato Agent as a multi-user, browser-based platform with isolated workspaces and online result preview, reducing the technical burden of agent deployment and providing direct access to integrated data, knowledge, and workflows. Case studies demonstrated its capabilities in reproducible bioinformatics analysis, agent-assisted identification of a tuber development regulator, scientific data visualization, and haplotype-aware promoter analysis and sgRNA design. Together, the agent-ready database and Potato Agent provide an integrated infrastructure for functional gene discovery and hybrid breeding in potato.

plant biology↗

bioRxiv2026

The vP300 Framework: Trial-to-Trial Variability in the P300 Event-Related Potential as a Signal of Locus Coeruleus-Norepinephrine Dynamics

The P300 event-related potential is one of the most studied electrophysiological markers of cognition, yet trial-to-trial variability within conditions has traditionally been treated as measurement error.The vP300 framework proposes that P300 variability, quantified by the coefficient of variation (CV), may reflect locus coeruleus-norepinephrine (LC-NE) mode dynamics. A computational simulation (N = 80) tested three hypotheses. Empirical P3 oddball data from the ERP CORE dataset (N = 39) provided partial validation. Mean amplitude and CV were orthogonal in simulation (r = -0.14, n.s.) and moderately correlated in empirical data (r = -0.418, p = .008), with 82.5% of CV variance independent of mean amplitude. CV significantly predicted cognitive flexibility (r = -0.319, p = .004) while mean amplitude did not (r = .010, p = .928). Trial- to-trial P300 variability carries information orthogonal to traditional mean amplitude, supporting a potential revision of how variability is treated in ERP research.

physiology↗

bioRxiv2026

In situ structural basis for the LHCSR3-mediated photoprotection of photosystem II

Energy-dependent quenching (qE) represents a critical mechanism for photosynthetic organisms to mitigate photodamage caused by excessive light. In green algae, LHCSR3 protein plays a central role in qE, activated by thylakoid lumen acidification and associated with photosystem II (PSII) to dissipate excess energy. Despite extensive efforts, the assembly and energy dissipation mechanisms of PSII-LHCSR3 have remained unknown. Here, we present the in situ structures of the PSII supercomplex embedded in the native thylakoid membranes of Chlamydomonas reinhardtii in both quenched (LHCSR3-bound) and unquenched (LHCSR3-free) states at near-atomic resolutions. Our results demonstrate that in high-light-acclimated cells, LHCSR3 binds to PSII peripheral antenna CP26 and associates with an extra LHCII trimer (eLHCII). Structural comparison of LHCSR3 with other light-harvesting complexes reveals possible protonation-induced conformational changes in LHCSR3 and rearrangements of its two pigment clusters, which potentially serve as quenching sites to dissipate excess energy transferred from CP26 and eLHCII. Our findings provide a direct visualization of how photoprotection is spatially organized in vivo and have implications for engineering natural and artificial photosynthetic systems with more dynamic photoprotection.

plant biology↗

bioRxiv2026

Data-adaptive three-dimensional deconvolution and evaluation for volumetric fluorescence microscopy

Optical fluorescence microscopy enables visualization of biological structures and dynamics. However, the intrinsic diffraction limit, especially axially, and depth-related scattering noise compromise the image resolution and fidelity. Computational 3D deconvolution is a promising approach for mitigating these issues, yet its execution is hindered by inaccurate and cumbersome theoretical modeling or experimental measurement of 3D point spread function (PSF), as well as ineffective 3D noise regularization. Furthermore, in the 3D super-resolution regime, there remains a lack of standardized tools for evaluating 3D super-resolution fidelity. Here, we present the 3D adaptive deconvolution and evaluation (3D-ADE) toolkit, which comprises 3D-Ada deconvolution with physics-oriented automatic 3D-PSF calibration, and 3D-SQUIRREL for 3D super-resolution quality assessment. It effectively resolves noise instability, eliminates the need for 3D-PSF calibration, and reliably assesses the fidelity of 3D resolution extension via deconvolution, physical, and deep-learning-based methods. Accessible via multiple software platforms, 3D-ADE enhances the versatility of 3D deconvolution and fills the gap in 3D super-resolution evaluation tools, and thereby advances volumetric fluorescence imaging applications.

bioengineering↗

bioRxiv2026

Modeling and validation of parallel co-flows layer widths in open-capillary trigger valve systems

Control of fluids is a hallmark of microfluidic systems and fundamental for the successful application of microfluidic devices. Trigger valves use geometric features to autonomously control the release of fluids in microfluidic devices. Our previous work has adapted geometries used in closed trigger valve systems to enable use in open systems, allowing for open microfluidic devices with up to three trigger valves. Here, we focus on the parallel co-flows produced by sequential release of trigger valves and present a model that predicts their layer widths as a function of the geometric characteristics of the different side channels of each trigger valve. We show layered co-flows with widths as low as 50 microns. Additionally, we expand the use of trigger valves in open microfluidic devices by incorporating 1) varied step heights, 2) devices with up to seven trigger valves, and 3) use of varied fluids and plastics. To validate the implementation and use of these trigger valves in open systems, we have developed a theoretical framework to compare predicted outcomes (i.e., fluid travel distance, velocity, and layering width) with our experimental values. This theoretical work offers applications in various fields, including hydrogel patterning for 3D cell culture, organ-on-a-chip models, at-home sample preparation, and autonomous microfluidic systems for biosensing.

bioengineering↗

bioRxiv2026

Killer-cell dominance dichotomy governs tumor immune networks and stratifies inflamed cancers

Cancer immunotherapy benefits remain limited, even among "hot" tumors with high killer lymphocyte infiltration. Here, we investigated the population-level architecture of killer cells based on nearly 5,000 pan-cancer scRNA-seq samples, together with orthogonal validation by spectral cytometry and spatial transcriptomics. Unlike the prevailing "hot-cold" paradigm, which assumes coordinated infiltration of multiple cytotoxic lineages, we uncovered a conserved framework wherein terminal cytotoxic immunity in individuals or malignancies diverges into states dominated by either exhausted CD8+ T cells (Tex) or CD56dimCD16hi NK (NK1) cells. Despite the complexity of the tumor microenvironment, Tex-NK1 divergence governs the primary axis of tumor-intrinsic and tumor-extrinsic variance. Distinct from the conventional view that NK cells positively contribute to immunotherapy efficacy, NK1-skewed tumors, although highly cytolytic, are refractory to current immune checkpoint blockade regimens. This killer divergence defines a foundational axis of cancer immunity and provides a resource for prioritizing next-generation targets for NK-directed immunotherapy.

immunology↗

bioRxiv2026

Physics-Driven Zero-Shot Reconstruction of Isotropic 3D Fluorescence Microscopy under Undersampled Acquisition

Three-dimensional (3D) imaging represents the development of next generation of fluorescence microscopy. However, routine axial down-sampling makes isotropic resolution unrealistic. Here, we propose DeepUI, a physical zero-shot framework designed to achieve isotropic 3D fluorescence images from a low axial sampling rate. DeepUI fully leverages the intrinsic characteristics of 3D images through physics-guided degradation, which incorporates spatial-frequency joint learning to generate a scaled optical transfer function, combined with noise degradation and an up-sampling branch. Typically requiring just 5 minutes for training and 0.5 minutes for high-throughput and fast prediction, we demonstrate the superior performance of DeepUI to get isotropic results, and the exclusivity to axial down-sampling conditions, even in more challenging conditions, including defocused background, noise, and resolution blur.

bioinformatics↗

bioRxiv2026

Generative design of antigen-specific T-cell receptor sequences with a conditional diffusion model

T cell receptor (TCR)-based immunotherapy holds immense potential for treating cancers, autoimmunity, and infectious diseases, where antigen-specific TCR recognition is crucial for adaptive immune responses. Engineering or de novo generation of the complementarity-determining region 3 (CDR3) loops of TCRs using artificial intelligence offers a powerful alternative to designing antigen-specific TCRs rather than laborious experimental screening. However, current in silico approaches are constrained by weak conditional guidance, limited flexibility, and a lack of rigorous functional validation. To address these limitations, we introduce TCRDiff, a generative diffusion framework for designing antigen-specific TCRs conditioned on peptide-MHC (pMHC) targets and germline-encoded TCR variable genes. By leveraging pre-trained knowledge from massive T-cell repertoires and TCR-pMHC recognition data, TCRDiff generates CDR3{beta} sequences that closely resemble native-binding TCRs via a denoising diffusion process. Furthermore, incorporating interface geometry features generated TCR-pMHC complexes with superior structural plausibility than models relying solely on sequence-based diffusion or structure-based modeling. As a proof of concept, we deployed TCRDiff in a systematic pipeline to design candidate TCRs against a clinically validated cancer antigen. In vitro activation assays validated that TCRDiff-generated TCRs efficiently recognize the MAGE-A3 epitope with minimal off-target reactivity. Thus, TCRDiff establishes a powerful, validated computational paradigm to accelerate the development of TCR-based immunotherapies.

bioinformatics↗

bioRxiv2026

Low-Energy Polishing Facilitates Breaking the Resolution Barrier of In Situ Cryo-EM

In situ structural analysis allows direct visualization of protein structures in their native cellular environments, but near-atomic resolution in cellular lamellae has been significantly limited to exceptionally large complexes such as ribosomes. A key factor underlying this limitation is the degradation of data quality of thin lamellae caused by substantial subsurface damage from cryo-focused ion beam (cryo-FIB). Here, we developed a cryogenic low-energy polishing in FIB approach, which reliably produces thin lamellae with low damage across different cell types. This advance, combined with in situ single particles analysis, has pushed down the molecular weight lower limit for in situ reconstruction at near-atomic resolution to [~]400 kDa. We demonstrate this by resolving photosynthetic complexes (3.4 [A] and 3.3 [A]), metabolic enzymes (3.3 [A]), chloroplast ribosome (4.0 [A]) and respiratory chain complexes (3.7 [A]) from Chlamydomonas reinhardtii. Furthermore, the efficient workflow enables rapid structural feedback upon changes in cellular states, offering a practical way to perform multi-condition in situ structural analysis.

biophysics↗

bioRxiv2026

Characterization of pre-analytical blood collection and stabilization parameters to maintain endogenous protein levels for remote blood sampling technology

Blood biomarkers are central to monitoring disease progression and evaluating treatment responses, yet traditional venipuncture captures a single physiological snapshot in time and becomes burdensome with repeated sampling. Remote blood self-sampling offers a path toward longitudinal, decentralized monitoring, but maintaining protein integrity from draw to analysis remains a critical challenge. Here, we optimized pre-analytical blood collection and stabilization parameters to maintain protein levels at the time of collection for use with remote sampling technology. First, we optimized blood collection time with Tasso remote self-sampling devices to minimize interference from clotting, finding that a 2.5 min collection time best reduces clot formation while collecting enough blood. Next, we found that Protein Plus, a commercial protein stabilizer, limited hemolysis (a metric for stabilizer efficacy) in venous blood for up to 5 days at 25{degrees}C-35{degrees}C and for 1 day at 40{degrees}C. In addition, we optimized the stabilizer volume and acceptable blood volume range for self-sampling as the stabilizer efficacy is impacted by the stabilizer to blood ratio and collection volume can vary with remote self-sampling devices. Finally, we incubated stabilized blood samples collected via Tasso device at 25{degrees}C-35{degrees}C for 72 h, mimicking a 2-day shipping period. Using a panel of 21 inflammatory proteins, we found that Protein Plus limited intracellular protein release for various proteins (e.g., VEGF-A, CCL11, and IL-8), inhibited protein degradation for CCL2, and enabled minimal hemolysis. These results support Protein Plus as a viable stabilization strategy for remote blood collection technology targeting longitudinal inflammatory protein monitoring.

biochemistry↗

bioRxiv2026

Deep quantitative phosphoproteomics identifies non-canonical pH-sensitive yeast phosphorylation networks

Changes in cellular pH act as potent upstream signals that rewire phosphorylation networks controlling cellular function and disease. In yeast, this response is thought to arise mainly from pH-dependent perturbations to membrane integrity and cell wall stress, which are relayed through TORC2- and PKC-dependent signaling pathways. Yet several proteins exhibit acid-dependent phosphorylation independently of TORC2 and PKC, pointing to additional, uncharacterized acid stress signaling mechanisms. To investigate this possibility, we performed SILAC-based deep phosphoproteomics to distinguish phosphoproteome changes that are dependent on plasma membrane and cell wall stress from those that are independent. Across more than 19,000 unique phosphosites, we identified over 1,000 sites whose acid stress-dependent regulation occurs outside the canonical acid stress pathways. These noncanonical targets were significantly enriched in proteins associated with the plasma membrane, GTPase-mediated signaling, and endocytosis. Motif analysis revealed enrichment of acidophilic substrates implicating the membrane-tethered casein kinase Yck1 as a major mediator of this response. In contrast, canonical acid stress signaling preferentially involved basophilic kinase substrates, while acid-repressed responses were enriched for proline-containing phosphosites involved in cell cycle progression. Collectively, these results uncover a distinct acid-responsive phosphorylation network that operates independently of plasma membrane and cell wall integrity signaling.

systems biology↗