WeiTsing, a pericycle-expressed ion channel, safeguards the stele to confer clubroot resistance.

Plant roots encounter numerous pathogenic microbes that often cause devastating diseases. One such pathogen, Plasmodiophora brassicae (Pb), causes clubroot disease and severe yield losses on cruciferous crops worldwide. Here, we report the isolation and characterization of WeiTsing (WTS), a broad-spectrum clubroot resistance gene from Arabidopsis. WTS is transcriptionally activated in the pericycle upon Pb infection to prevent pathogen colonization in the stele. Brassica napus carrying the WTS transgene displayed strong resistance to Pb. WTS encodes a small protein localized in the endoplasmic reticulum (ER), and its expression in plants induces immune responses. The cryoelectron microscopy (cryo-EM) structure of WTS revealed a previously unknown pentameric architecture with a central pore. Electrophysiology analyses demonstrated that WTS is a calcium-permeable cation-selective channel. Structure-guided mutagenesis indicated that channel activity is strictly required for triggering defenses. The findings uncover an ion channel analogous to resistosomes that triggers immune signaling in the pericycle.

A hot-emitter transistor based on stimulated emission of heated carriers.

Hot-carrier transistors are a class of devices that leverage the excess kinetic energy of carriers. Unlike regular transistors, which rely on steady-state carrier transport, hot-carrier transistors modulate carriers to high-energy states, resulting in enhanced device speed and functionality. These characteristics are essential for applications that demand rapid switching and high-frequency operations, such as advanced telecommunications and cutting-edge computing technologies1-5. However, the traditional mechanisms of hot-carrier generation are either carrier injection6-11 or acceleration12,13, which limit device performance in terms of power consumption and negative differential resistance14-17. Mixed-dimensional devices, which combine bulk and low-dimensional materials, can offer different mechanisms for hot-carrier generation by leveraging the diverse potential barriers formed by energy-band combinations18-21. Here we report a hot-emitter transistor based on double mixed-dimensional graphene/germanium Schottky junctions that uses stimulated emission of heated carriers to achieve a subthreshold swing lower than 1 millivolt per decade beyond the Boltzmann limit and a negative differential resistance with a peak-to-valley current ratio greater than 100 at room temperature. Multi-valued logic with a high inverter gain and reconfigurable logic states are further demonstrated. This work reports a multifunctional hot-emitter transistor with significant potential for low-power and negative-differential-resistance applications, marking a promising advancement for the post-Moore era.

Splicing factor YBX1 regulates bone marrow stromal cell fate during aging.

Senescence and altered differentiation potential of bone marrow stromal cells (BMSCs) lead to age-related bone loss. As an important posttranscriptional regulatory pathway, alternative splicing (AS) regulates the diversity of gene expression and has been linked to induction of cellular senescence. However, the role of splicing factors in BMSCs during aging remains poorly defined. Herein, we found that the expression of the splicing factor Y-box binding protein 1 (YBX1) in BMSCs decreased with aging in mice and humans. YBX1 deficiency resulted in mis-splicing in genes linked to BMSC osteogenic differentiation and senescence, such as Fn1, Nrp2, Sirt2, Sp7, and Spp1, thus contributing to BMSC senescence and differentiation shift during aging. Deletion of Ybx1 in BMSCs accelerated bone loss in mice, while its overexpression stimulated bone formation. Finally, we identified a small compound, sciadopitysin, which attenuated the degradation of YBX1 and bone loss in old mice. Our study demonstrated that YBX1 governs cell fate of BMSCs via fine control of RNA splicing and provides a potential therapeutic target for age-related osteoporosis.

A New Orthonairovirus Associated with Human Febrile Illness.

BACKGROUND: In June 2019, a patient presented with persistent fever and multiple organ dysfunction after a tick bite at a wetland park in Inner Mongolia. Next-generation sequencing in this patient revealed an infection with a previously unknown orthonairovirus, which we designated Wetland virus (WELV). METHODS: We conducted active hospital-based surveillance to determine the prevalence of WELV infection among febrile patients with a history of tick bites. Epidemiologic investigation was performed. The virus was isolated, and its infectivity and pathogenicity were investigated in animal models. RESULTS: WELV is a member of the orthonairovirus genus in the Nairoviridae family and is most closely related to the tickborne Hazara orthonairovirus genogroup. Acute WELV infection was identified in 17 patients from Inner Mongolia, Heilongjiang, Jilin, and Liaoning, China, by means of reverse-transcriptase-polymerase-chain-reaction assay. These patients presented with nonspecific symptoms, including fever, dizziness, headache, malaise, myalgia, arthritis, and back pain and less frequently with petechiae and localized lymphadenopathy. One patient had neurologic symptoms. Common laboratory findings were leukopenia, thrombocytopenia, and elevated d-dimer and lactate dehydrogenase levels. Serologic assessment of convalescent-stage samples obtained from 8 patients showed WELV-specific antibody titers that were 4 times as high as those in acute-phase samples. WELV RNA was detected in five tick species and in sheep, horses, pigs, and Transbaikal zokors (Myospalax psilurus) sampled in northeastern China. The virus that was isolated from the index patient and ticks showed cytopathic effects in human umbilical-vein endothelial cells. Intraperitoneal injection of the virus resulted in lethal infections in BALB/c, C57BL/6, and Kunming mice. The Haemaphysalis concinna tick is a possible vector that can transovarially transmit WELV. CONCLUSIONS: A newly discovered orthonairovirus was identified and shown to be associated with human febrile illnesses in northeastern China. (Funded by the National Natural Science Foundation of China and the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences.).

Deletion variants calling in third-generation sequencing data based on a dual-attention mechanism.

Deletion is a crucial type of genomic structural variation and is associated with numerous genetic diseases. The advent of third-generation sequencing technology has facilitated the analysis of complex genomic structures and the elucidation of the mechanisms underlying phenotypic changes and disease onset due to genomic variants. Importantly, it has introduced innovative perspectives for deletion variants calling. Here we propose a method named Dual Attention Structural Variation (DASV) to analyze deletion structural variations in sequencing data. DASV converts gene alignment information into images and integrates them with genomic sequencing data through a dual attention mechanism. Subsequently, it employs a multi-scale network to precisely identify deletion regions. Compared with four widely used genome structural variation calling tools: cuteSV, SVIM, Sniffles and PBSV, the results demonstrate that DASV consistently achieves a balance between precision and recall, enhancing the F1 score across various datasets. The source code is available at https://github.com/deconvolution-w/DASV.

GGN-GO: geometric graph networks for predicting protein function by multi-scale structure features.

Recent advances in high-throughput sequencing have led to an explosion of genomic and transcriptomic data, offering a wealth of protein sequence information. However, the functions of most proteins remain unannotated. Traditional experimental methods for annotation of protein functions are costly and time-consuming. Current deep learning methods typically rely on Graph Convolutional Networks to propagate features between protein residues. However, these methods fail to capture fine atomic-level geometric structural features and cannot directly compute or propagate structural features (such as distances, directions, and angles) when transmitting features, often simplifying them to scalars. Additionally, difficulties in capturing long-range dependencies limit the model's ability to identify key nodes (residues). To address these challenges, we propose a geometric graph network (GGN-GO) for predicting protein function that enriches feature extraction by capturing multi-scale geometric structural features at the atomic and residue levels. We use a geometric vector perceptron to convert these features into vector representations and aggregate them with node features for better understanding and propagation in the network. Moreover, we introduce a graph attention pooling layer captures key node information by adaptively aggregating local functional motifs, while contrastive learning enhances graph representation discriminability through random noise and different views. The experimental results show that GGN-GO outperforms six comparative methods in tasks with the most labels for both experimentally validated and predicted protein structures. Furthermore, GGN-GO identifies functional residues corresponding to those experimentally confirmed, showcasing its interpretability and the ability to pinpoint key protein regions. The code and data are available at: https://github.com/MiJia-ID/GGN-GO.

Tomato MED25 regulates fruit ripening by interacting with EIN3-like transcription factors.

Fruit ripening relies on the precise spatiotemporal control of RNA polymerase II (Pol II)-dependent gene transcription, and the evolutionarily conserved Mediator (MED) coactivator complex plays an essential role in this process. In tomato (Solanum lycopersicum), a model climacteric fruit, ripening is tightly coordinated by ethylene and several key transcription factors. However, the mechanism underlying the transmission of context-specific regulatory signals from these ripening-related transcription factors to the Pol II transcription machinery remains unknown. Here, we report the mechanistic function of MED25, a subunit of the plant Mediator transcriptional coactivator complex, in controlling the ethylene-mediated transcriptional program during fruit ripening. Multiple lines of evidence indicate that MED25 physically interacts with the master transcription factors of the ETHYLENE-INSENSITIVE 3 (EIN3)/EIN3-LIKE (EIL) family, thereby playing an essential role in pre-initiation complex formation during ethylene-induced gene transcription. We also show that MED25 forms a transcriptional module with EIL1 to regulate the expression of ripening-related regulatory as well as structural genes through promoter binding. Furthermore, the EIL1-MED25 module orchestrates both positive and negative feedback transcriptional circuits, along with its downstream regulators, to fine-tune ethylene homeostasis during fruit ripening.

Understanding asymmetric switching times in accumulation mode organic electrochemical transistors.

Understanding the factors underpinning device switching times is crucial for the implementation of organic electrochemical transistors in neuromorphic computing, bioelectronics and real-time sensing applications. Existing models of device operation cannot explain the experimental observations that turn-off times are generally much faster than turn-on times in accumulation mode organic electrochemical transistors. Here, using operando optical microscopy, we image the local doping level of the transistor channel and show that turn-on occurs in two stages-propagation of a doping front, followed by uniform doping-while turn-off occurs in one stage. We attribute the faster turn-off to a combination of engineering as well as physical and chemical factors including channel geometry, differences in doping and dedoping kinetics and the phenomena of carrier-density-dependent mobility. We show that ion transport limits the operation speed in our devices. Our study provides insights into the kinetics of organic electrochemical transistors and guidelines for engineering faster organic electrochemical transistors.

In vivo HSC prime editing rescues sickle cell disease in a mouse model.

Sickle cell disease (SCD) is a monogenic disease caused by a nucleotide mutation in the ß-globin gene. Current gene therapy studies are mainly focused on lentiviral vector-mediated gene addition or CRISPR/Cas9-mediated fetal globin reactivation, leaving the root cause unfixed. We developed a vectorized prime editing system that can directly repair the SCD mutation in hematopoietic stem cells (HSCs) in vivo in a SCD mouse model (CD46/Townes mice). Our approach involved a single intravenous injection of a nonintegrating, prime editor-expressing viral vector into mobilized CD46/Townes mice and low-dose drug selection in vivo. This procedure resulted in the correction of ∼40% of ßS alleles in HSCs. On average, 43% of sickle hemoglobin was replaced by adult hemoglobin, thereby greatly mitigating the SCD phenotypes. Transplantation in secondary recipients demonstrated that long-term repopulating HSCs were edited. Highly efficient target site editing was achieved with minimal generation of insertions and deletions and no detectable off-target editing. Because of its simplicity and portability, our in vivo prime editing approach has the potential for application in resource-poor countries where SCD is prevalent.

Introducing a G-Makassar variant in HSCs by in vivo base editing treats sickle cell disease in mice.

Precise repair of the pathogenic mutation in hematopoietic stem cells (HSCs) represents an ideal cure for patients with sickle cell disease (SCD). Here, we demonstrated correction of the SCD phenotype by converting the sickle mutation codon (GTG) into a benign G-Makassar variant (GCG) using in vivo base editing in HSCs. We demonstrated successful production of helper-dependent adenoviral vectors expressing an all-in-one base editor mapping to the sickle mutation site. In HSC-enriched cells from SCD patients, transduction with the base editing vector in vitro resulted in 35% GTG > GCG conversion and phenotypic improvements of derived red blood cells. After ex vivo transduction of HSCs from a SCD mouse model and subsequent transplantation, we achieved an average of 88% editing at the target site in transplanted mice. Importantly, in vivo HSC base editing followed by selection generated 24.5% Makassar variant in long-term repopulating HSCs of SCD mice. The treated animals demonstrated correction of disease hallmarks without showing noticeable side effects. Off-target analyses at top-scored genomic sites revealed no off-target editing. This in vivo approach requires only one non-integrating vector, only intravenous/subcutaneous injections, and minimal in vivo selection. This technically simple approach has the potential for scalable applications in resource-limiting regions where SCD is prevalent.

Chemical Proteomic Approach for In-Depth Glycosylation Profiling of Plasma Carcinoembryonic Antigen in Cancer Patients.

Carcinoembryonic antigen (CEA) of human plasma is a biomarker of many cancer diseases, and its N-glycosylation accounts for 60% of molecular mass. It is highly desirable to characterize its glycoforms for providing additional dimension of features to increase its performance in prognosis and diagnosis of cancers. However, to systematically characterize its site-specific glycosylation is challenging because of its low abundance. Here, we developed a highly sensitive strategy for in-depth glycosylation profiling of plasma CEA through chemical proteomics combined with multienzymatic digestion. A trifunctional probe was utilized to generate covalent bond of plasma CEA and its antibody upon UV irradiation. As low as 1 ng/ml CEA in plasma could be captured and digested with trypsin and chymotrypsin for intact glycopeptide characterization. Twenty six of 28 potential N-glycosylation sites were well identified, which were the most comprehensive N-glycosylation site characterization of CEA on intact glycopeptide level as far as we known. Importantly, this strategy was applied to the glycosylation analysis of plasma CEA in cancer patients. Differential site-specific glycoforms of plasma CEA were observed in patients with colorectal cancers (CRCs) and lung cancer. The distributions of site-specific glycoforms were different as the progression of CRC, and most site-specific glycoforms were overexpressed in stage II of CRC. Overall, we established a highly sensitive chemical proteomic method to profile site-specific glycosylation of plasma CEA, which should generally applicable to other well-established cancer glycoprotein biomarkers for improving their cancer diagnosis and monitoring performance.

A precise and efficient circular RNA synthesis system based on a ribozyme derived from Tetrahymena thermophila.

Classic strategies for circular RNA (circRNA) preparation always introduce large numbers of linear transcripts or extra nucleotides to the circularized product. In this study, we aimed to develop an efficient system for circRNA preparation based on a self-splicing ribozyme derived from an optimized Tetrahymena thermophila group Ⅰ intron. The target RNA sequence was inserted downstream of the ribozyme and a complementary antisense region was added upstream of the ribozyme to assist cyclization. Then, we compared the circularization efficiency of ribozyme or flanking intronic complementary sequence (ICS)-mediated methods through the DNMT1, CDR1as, FOXO3, and HIPK3 genes and found that the efficiency of our system was remarkably higher than that of flanking ICS-mediated method. Consequently, the circularized products mediated by ribozyme are not introduced with additional nucleotides. Meanwhile, the overexpressed circFOXO3 maintained its biological functions in regulating cell proliferation, migration, and apoptosis. Finally, a ribozyme-based circular mRNA expression system was demonstrated with a split green fluorescent protein (GFP) using an optimized Coxsackievirus B3 (CVB3) internal ribosome entry site (IRES) sequence, and this system achieved successful translation of circularized mRNA. Therefore, this novel, convenient, and rapid engineering RNA circularization system can be applied for the functional study and large-scale preparation of circular RNA in the future.

Structural basis of Tom20 and Tom22 cytosolic domains as the human TOM complex receptors.

Mitochondrial preproteins synthesized in cytosol are imported into mitochondria by a multisubunit translocase of the outer membrane (TOM) complex. Functioned as the receptor, the TOM complex components, Tom 20, Tom22, and Tom70, recognize the presequence and further guide the protein translocation. Their deficiency has been linked with neurodegenerative diseases and cardiac pathology. Although several structures of the TOM complex have been reported by cryoelectron microscopy (cryo-EM), how Tom22 and Tom20 function as TOM receptors remains elusive. Here we determined the structure of TOM core complex at 2.53 Å and captured the structure of the TOM complex containing Tom22 and Tom20 cytosolic domains at 3.74 Å. Structural analysis indicates that Tom20 and Tom22 share a similar three-helix bundle structural feature in the cytosolic domain. Further structure-guided biochemical analysis reveals that the Tom22 cytosolic domain is responsible for binding to the presequence, and the helix H1 is critical for this binding. Altogether, our results provide insights into the functional mechanism of the TOM complex recognizing and transferring preproteins across the mitochondrial membrane.

The global succinylation of SARS-CoV-2-infected host cells reveals drug targets.

SARS-CoV-2, the causative agent of the COVID-19 pandemic, undergoes continuous evolution, highlighting an urgent need for development of novel antiviral therapies. Here we show a quantitative mass spectrometry-based succinylproteomics analysis of SARS-CoV-2 infection in Caco-2 cells, revealing dramatic reshape of succinylation on host and viral proteins. SARS-CoV-2 infection promotes succinylation of several key enzymes in the TCA, leading to inhibition of cellular metabolic pathways. We demonstrated that host protein succinylation is regulated by viral nonstructural protein (NSP14) through interaction with sirtuin 5 (SIRT5); overexpressed SIRT5 can effectively inhibit virus replication. We found succinylation inhibitors possess significant antiviral effects. We also found that SARS-CoV-2 nucleocapsid and membrane proteins underwent succinylation modification, which was conserved in SARS-CoV-2 and its variants. Collectively, our results uncover a regulatory mechanism of host protein posttranslational modification and cellular pathways mediated by SARS-CoV-2, which may become antiviral drug targets against COVID-19.

Non-coding RNA yREX3 from human extracellular vesicles exerts macrophage-mediated cardioprotection via a novel gene-methylating mechanism.

BACKGROUND AND AIMS: Extracellular vesicles (EVs) secreted by cardiosphere-derived cells exert immunomodulatory effects through the transmission of small non-coding RNAs. METHODS: The mechanism and role of yREX3, a small Y RNA abundant in EVs in myocardial injury, was investigated. RESULTS: yREX3 attenuates cardiac ischaemic injury by selective DNA methylation. Synthetic yREX3 encapsulated in lipid nanoparticles triggers broad transcriptomic changes in macrophages, localizes to the nucleus, and mediates epigenetic silencing of protein interacting with C kinase-1 (Pick1) through methylation of upstream CpG sites. Moreover, yREX3 interacts with polypyrimidine tract binding protein 3 (PTBP3) to methylate the Pick1 gene locus in a DNA methyltransferase-dependent manner. Suppression of Pick1 in macrophages potentiates Smad3 signalling and enhances efferocytosis, minimizing heart necrosis in rats with myocardial infarction. Adoptive transfer of Pick1-deficient macrophages recapitulates the cardioprotective effects of yREX3 in vivo. CONCLUSIONS: These findings highlight the role of a small Y RNA mined from EVs with a novel gene-methylating mechanism.

ViroISDC: a method for calling integration sites of hepatitis B virus based on feature encoding.

BACKGROUND: Hepatitis B virus (HBV) integrates into human chromosomes and can lead to genomic instability and hepatocarcinogenesis. Current tools for HBV integration site detection lack accuracy and stability. RESULTS: This study proposes a deep learning-based method, named ViroISDC, for detecting integration sites. ViroISDC generates corresponding grammar rules and encodes the characteristics of the language data to predict integration sites accurately. Compared with Lumpy, Pindel, Seeksv, and SurVirus, ViroISDC exhibits better overall performance and is less sensitive to sequencing depth and integration sequence length, displaying good reliability, stability, and generality. Further downstream analysis of integrated sites detected by ViroISDC reveals the integration patterns and features of HBV. It is observed that HBV integration exhibits specific chromosomal preferences and tends to integrate into cancerous tissue. Moreover, HBV integration frequency was higher in males than females, and high-frequency integration sites were more likely to be present on hepatocarcinogenesis- and anti-cancer-related genes, validating the reliability of the ViroISDC. CONCLUSIONS: ViroISDC pipeline exhibits superior precision, stability, and reliability across various datasets when compared to similar software. It is invaluable in exploring HBV infection in the human body, holding significant implications for the diagnosis, treatment, and prognosis assessment of HCC.

DNA methylation regulates the secondary metabolism of saponins to improve the adaptability of Eleutherococcus senticosus during drought stress.

Plant growth and development can be significantly impacted by drought stress. Plants will adjust the synthesis and accumulation of secondary metabolites to improve survival in times of water constraint. Simultaneously, drought stress can lead to modifications in the DNA methylation status of plants, and these modifications can directly impact gene expression and product synthesis by changing the DNA methylation status of functional genes involved in secondary metabolite synthesis. However, further research is needed to fully understand the extent to which DNA methylation modifies the content of secondary metabolites to mediate plants' responses to drought stress, as well as the underlying mechanisms involved. Our study found that in Eleutherococcus senticosus (E. senticosus), moderate water deprivation significantly decreased DNA methylation levels throughout the genome and at the promoters of EsFPS, EsSS, and EsSE. Transcription factors like EsMYB-r1, previously inhibited by DNA methylation, can re-bind to the EsFPS promotor region following DNA demethylation. This process promotes gene expression and, ultimately, saponin synthesis and accumulation. The increased saponin levels in E. senticosus acted as antioxidants, enhancing the plant's adaptability to drought stress.

Identification and expression analysis of ATP-binding cassette (ABC) transporters revealed its role in regulating stress response in pear (Pyrus bretchneideri).

BACKGROUND: ATP-binding cassette (ABC) transporter proteins constitute a plant gene superfamily crucial for growth, development, and responses to environmental stresses. Despite their identification in various plants like maize, rice, and Arabidopsis, little is known about the information on ABC transporters in pear. To investigate the functions of ABC transporters in pear development and abiotic stress response, we conducted an extensive analysis of ABC gene family in the pear genome. RESULTS: In this study, 177 ABC transporter genes were successfully identified in the pear genome, classified into seven subfamilies: 8 ABCAs, 40 ABCBs, 24 ABCCs, 8 ABCDs, 9 ABCEs, 8 ABCFs, and 80 ABCGs. Ten motifs were common among all ABC transporter proteins, while distinct motif structures were observed for each subfamily. Distribution analysis revealed 85 PbrABC transporter genes across 17 chromosomes, driven primarily by WGD and dispersed duplication. Cis-regulatory element analysis of PbrABC promoters indicated associations with phytohormones and stress responses. Tissue-specific expression profiles demonstrated varied expression levels across tissues, suggesting diverse functions in development. Furthermore, several PbrABC genes responded to abiotic stresses, with 82 genes sensitive to salt stress, including 40 upregulated and 23 downregulated genes. Additionally, 91 genes were responsive to drought stress, with 22 upregulated and 36 downregulated genes. These findings highlight the pivotal role of PbrABC genes in abiotic stress responses. CONCLUSION: This study provides evolutionary insights into PbrABC transporter genes, establishing a foundation for future research on their functions in pear. The identified motifs, distribution patterns, and stress-responsive expressions contribute to understanding the regulatory mechanisms of ABC transporters in pear. The observed tissue-specific expression profiles suggest diverse roles in developmental processes. Notably, the significant responses to salt and drought stress emphasize the importance of PbrABC genes in mediating adaptive responses. Overall, our study advances the understanding of PbrABC transporter genes in pear, opening avenues for further investigations in plant molecular biology and stress physiology.

KDM5 family as therapeutic targets in breast cancer: Pathogenesis and therapeutic opportunities and challenges.

Breast cancer (BC) is the most frequent malignant cancer diagnosis and is a primary factor for cancer deaths in women. The clinical subtypes of BC include estrogen receptor (ER) positive, progesterone receptor (PR) positive, human epidermal growth factor receptor 2 (HER2) positive, and triple-negative BC (TNBC). Based on the stages and subtypes of BC, various treatment methods are available with variations in the rates of progression-free disease and overall survival of patients. However, the treatment of BC still faces challenges, particularly in terms of drug resistance and recurrence. The study of epigenetics has provided new ideas for treating BC. Targeting aberrant epigenetic factors with inhibitors represents a promising anticancer strategy. The KDM5 family includes four members, KDM5A, KDM5B, KDM5C, and KDMD, all of which are Jumonji C domain-containing histone H3K4me2/3 demethylases. KDM5 proteins have been extensively studied in BC, where they are involved in suppressing or promoting BC depending on their specific upstream and downstream pathways. Several KDM5 inhibitors have shown potent BC inhibitory activity in vitro and in vivo, but challenges still exist in developing KDM5 inhibitors. In this review, we introduce the subtypes of BC and their current therapeutic options, summarize KDM5 family context-specific functions in the pathobiology of BC, and discuss the outlook and pitfalls of KDM5 inhibitors in this disease.

CircPCNXL2 promotes tumor growth and metastasis by interacting with STRAP to regulate ERK signaling in intrahepatic cholangiocarcinoma.

BACKGROUND: circular RNAs (circRNAs) have been reported to exert important effects in the progression of numerous cancers. However, the functions of circRNAs in intrahepatic cholangiocarcinoma (ICC) are still unclear. METHODS: circPCNXL2 (has_circ_0016956) were identified in paired ICC by circRNA microarray. Then, we assessed the biological functions of circPCNXL2 by CCK8, EdU, clone formation, transwell, wound healing assays, and xenograft models. RNA pull-down, mass spectrometry, and RNA immunoprecipitation (RIP) were applied to explore the interaction between cirrcPCNXL2 and serine-threonine kinase receptor-associated protein (STRAP). RNA pull-down, RIP and luciferase reporter assays were used to investigate the sponge functions of circPCNXL2. In the end, we explore the effects of circPCNXL2 and trametinib (a MEK1/2 inhibitor) in vivo. RESULTS: circPCNXL2 was upregulated in ICC tissues and cell lines, which promoted the proliferation and metastasis of ICC in vitro and in vivo. In terms of the mechanisms, circPCNXL2 could directly bind to STRAP and induce the interaction between STRAP and MEK1/2, resulting in the tumor promotion in ICC by activation of ERK/MAPK pathways. Besides, circPCNXL2 could regulate the expression of SRSF1 by sponging miR-766-3p and subsequently facilitated the growth of ICC. Finally, circPCNXL2 could partially inhibit the anti-tumor activity of trametinib in vivo. CONCLUSION: circPCNXL2 played a crucial role in the progression of ICC by interacting with STRAP to activate the ERK signaling pathway, as well as by modulating the miR-766-3p/SRSF1 axis. These findings suggest that circPCNXL2 may be a promising biomarker and therapeutic target for ICC.