Hepatocellular carcinoma (HCC) is a highly lethal malignancy with obvious heterogeneity features. This study aims to identify circRNAs with key roles in promoting HCC malignancy and stemness properties. Through circRNA profiling comparison in HCC patients and functional screening in HCC cells, circRSU1 emerges as the top candidate. It exhibits a significant higher expression level in tumor tissues compared to adjacent non-tumor liver tissues from HCC patients. Functionally, circRSU1 promotes a spectrum of HCC malignant phenotypes both in vitro and in vivo, including an enrichment of CD24positive cancer stem cell population. Mechanistically, circRSU1 interacts with heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) via two RNA motifs on circRSU1 and two RNA-binding domains on hnRNPA1. This interaction increases hnRNPA1 protein level via reducing its proteasomal degradation. Furthermore, hnRNPA1 enhances HIF-1α protein translation via binding to its internal ribosome entry site (IRES), which subsequently increases the CD24positive cell population. Additionally, circRSU1 further enhances this process not only through increasing the hnRNPA1 protein level, but also through enhancing the interaction of hnRNPA1 with HIF1A IRES, consequently augmenting the CD24positive cell population and the associated malignancy/stemness features of HCC cells. Together, circRSU1 activates the hnRNPA1/HIF-1α/CD24 signaling axis, leading to the increased HCC malignancy and stemness features.

ZNRF3 and RNF43 are closely related transmembrane E3 ubiquitin ligases with significant roles in development and cancer. Conventionally, their biological functions have been associated with regulating WNT signaling receptor ubiquitination and degradation. However, our proteogenomic studies have revealed EGFR as the protein most negatively correlated with ZNRF3/RNF43 mRNA levels in multiple human cancers. Through biochemical investigations, we demonstrate that ZNRF3/RNF43 interact with EGFR via their extracellular domains, leading to EGFR ubiquitination and subsequent degradation facilitated by the E3 ligase RING domain. Overexpression of ZNRF3 reduces EGFR levels and suppresses cancer cell growth in vitro and in vivo, whereas knockout of ZNRF3/RNF43 stimulates cell growth and tumorigenesis through upregulated EGFR signaling. Together, these data suggest ZNRF3 and RNF43 as novel E3 ubiquitin ligases of EGFR and establish the inactivation of ZNRF3/RNF43 as a driver of increased EGFR signaling, ultimately promoting cancer progression. This discovery establishes a connection between two fundamental signaling pathways, EGFR and WNT, at the level of cytoplasmic membrane receptors, uncovering a novel mechanism underlying the frequent co-activation of EGFR and WNT signaling in development and cancer.

Mitosis is tightly regulated at multiple levels to ensure chromosome stability. The transient phosphorylation of histone H3 at Threonine 3 (H3T3) during cell division is critical for proper chromosome condensation and the accurate segregation of sister chromatids. While Haspin has been identified as the kinase responsible for H3T3 phosphorylation during mitosis, the phosphatases that counteract this modification to maintain balanced phosphorylation levels remain under investigation. In this study, we systematically screened phosphatases encoded in the human genome and identified the nuclear phosphatase SCP4 as an H3T3 phosphatase. SCP4 modulates H3T3 phosphorylation levels and influences the chromosomal recruitment of chromosomal passenger complex (CPC) during mitosis. Aberrant SCP4 expression leads to defective chromosome separation during metaphase and chromosome lagging in anaphase, resulting in aneuploidy. Notably, in SCP4 knockout mice, zygotes exhibit mitotic defects during the first cleavage at the two-cell stage, highlighting SCP4's essential role in ensuring faithful cell division. In summary, we identify SCP4 as a novel phosphatase regulating H3T3 phosphorylation and chromosome dynamics during mitosis, providing new insights into mechanisms safeguarding genomic stability.

Transforming growth factor-β (TGF-β) is a multifunctional cytokine that regulates cell proliferation, differentiation, migration, and apoptosis. It is generally accepted that TGF-β induces cellular responses through Smad-dependent gene transcription. However, the underlying mechanisms that modulate the transcriptional activities of Smads are not yet fully understood. Here, we identify BRD2, a member of the bromodomain and extraterminal (BET) family, as a key transcriptional coactivator for Smad3. BRD2 physically interacts with Smad3 through a newly identified Smad3-binding region (SBR). This BRD2-Smad interaction enhances Smad’s association with chromatin and amplifies its transcriptional activity, playing a vital role in TGF-β transcriptional and tumor-suppressive responses. Our findings establish BRD2 as an important modulator of TGF-β signaling and suggest that it may serve as a potential target for TGF-β-related diseases.

N6-methyladenosine (m6A) is the most prevalent internal modification of mRNA and is frequently dysregulated in cancer. However, the roles of m6A and its modifiers, such as the methyltransferase METTL3, remain controversial in primary tumors. We report that METTL3 is upregulated in the highly proliferative human S2 and mouse M2 subtypes of hepatocellular carcinoma (HCC). Integrated analyses of the RNA methylome, transcriptome and proteome identify Birc6 as a direct downstream target of Mettl3. Using CRISPR/dCas13b-mediated site-specific methylation, we demonstrate that m6A deposition at three conserved sites enhances Birc6 translation, thereby promoting degradation of caspase-7 and caspase-9 and suppressing apoptosis. Multiplexed in situ genome editing in mouse hepatocytes shows that Mettl3 promotes hepatocarcinogenesis in a cell-autonomous manner through Birc6. Together, our findings establish a functional link between METTL3-mediated m6A modification and BIRC6-mediated apoptosis inhibition in liver tumorigenesis, suggesting BIRC6 as a potential therapeutic target in HCC. Multi-omic profiling combined with multiplexed in situ genome editing in mouse hepatocytes demonstrates that METTL3 drives hepatocarcinogenesis via m⁶A modification of BIRC6 mRNA, identifying METTL3 and BIRC6 as promising therapeutic targets for hepatocellular carcinoma.

Cytokines from the transforming growth factor-β (TGF-β) superfamily are essential regulators of cell growth, survival, and differentiation, playing a pivotal role in mammalian embryonic development, adult tissue homeostasis, and progression of human diseases. Recently, an international symposium on TGF-β Signaling in Development and Diseases was held in Nanchang, China, from October 21 to 23, 2025. This event showcased the latest advances in TGF-β signaling and its pathophysiological functions. Over ten presentations at the symposium offered new insights on Smad-dependent and non-Smad TGF-β signaling, its spatiotemporal regulation, and multifaceted roles of TGF-β family cytokines in various pathophysiological contexts. The symposium also addressed potential strategies and opportunities for targeting the TGF-β pathway in the treatment of human diseases.

EGFR hotspot mutations (mEGFR), including primary L858R, exon 19 deletion, and secondary T790M, are pivotal oncogenic drivers in human non-small cell lung cancer (NSCLC). At the same time, NSCLC resistance to third-generation tyrosine kinase inhibitors (TKIs) is a major clinical challenge and remains mechanistically unresolved. Here, we uncover a previously unrecognized tumor cell-intrinsic mechanism in which mutant EGFR (mEGFR) exploits innate immune signaling via the cGAS-STING-TBK1 pathway to sustain oncogenic signaling and therapeutic resistance. Mechanistically, mutant EGFR kinase aberrantly associates with STING signalosomes and phosphorylates STING (Y245/Y314) and TBK1 (Y577/Y677), stabilizing and hyperactivating TBK1 and establishing an unexpected kinase loop critical for DNA damage repair. Genetic or pharmacological disruption of mEGFR-STING-TBK1 coupling sensitizes resistant patient-derived NSCLC organoids to chemotherapy. Combining TBK1 inhibition with cisplatin suppressed mEGFR-driven tumors in murine models of spontaneous and immunocompetent NSCLC and in patient-derived organoids. Our findings suggest a new function of cGAS-STING in DNA damage tolerance, its paradoxical exploitation by oncogenic driver mutations, and an innate immune therapeutic vulnerability in NSCLC.

Pyroptosis, a pro-inflammatory form of programmed cell death, is crucial for host defense against pathogens and danger signals. Proteolytic cleavage of gasdermin proteins B-E (GSDMB-GSDME) is well established as a trigger for pyroptosis, but the intracellular activation mechanism of GSDMA remains elusive. Here, we demonstrate that severe starvation induces pyroptosis through phosphorylation-induced activation of GSDMA. Nutrient stresses stimulate GSDMA activation via phosphorylation mediated by Unc-51-like autophagy-activating kinase 1 (ULK1). Phosphorylation of Ser353 on human GSDMA by ULK1 or the phospho-mimetic Ser353Asp mutant of GSDMA liberates GSDMA from auto-inhibition, facilitating its membrane targeting and initiation of pyroptosis. To further validate the significance of GSDMA phosphorylation, we generated a constitutively active mutant Ser354Asp of mouse Gsdma, which induced skin inflammation and hyperplasia in mice, reminiscent of phenotypes with activated Gsdma. This study uncovers phosphorylation of GSDMA as a mechanism underlying pyroptosis initiation and cellular response to nutrient stress.

Intratumoral glucose availability links considerably to tumor growth, immune evasion, and metastasis. However, the precise mechanisms by which glucose levels govern cellular and immune responses remain incompletely understood. Here, we explored the intersections between AMP-activated protein kinase (AMPK) and cGAS-STING signaling, a key pathway initiating antitumor immunity. We unexpectedly found that AMPK activation robustly enhances cGAS-STING signaling within cancer and immune cells, which potently impacts melanoma and colorectal cell senescence, organoid apoptosis, and the infiltration of CD4+ and CD8+ T lymphocytes. Using classic or newly developed AMPK agonist Aldometanib, TBK1S511E/S511E knock-in (KI) mice, glucose metabolic modulator, and AMPK?1/?2 dKO melanoma, we demonstrated that dual sensing of intratumoral glucose and dsDNA integrated by the AMPK-TBK1 cascade is essential for initiating antitumor immunity and suppressing cancer progressions. Notably, novel AMPK agonists or intervening in glucose glycolysis by Lonidamine synergized effectively with STING agonists, substantially inhibiting melanoma growth. Therefore, these findings unravel a concise mechanism integrating glucose metabolism and innate DNA sensing into cancer cell fate and propose an effective therapeutic strategy to enhance antitumor immunity. ### Competing Interest Statement The authors have declared no competing interest.

The basal layer progenitors establish a stratified epidermis through asymmetric division and differentiation. Inactivating mutations of Receptor-interacting serine/threonine kinase 4 (RIPK4) cause human developmental syndromes characterized by defective epidermal differentiation. While the Hippo pathway is crucial in limiting organ size, emerging evidence suggests that it also plays additional roles in differentiation. In this study, we identify RIPK4 as an alternative upstream kinase of LATS1/2 in the Hippo pathway through screening a kinome library. Ripk4 knockout in mice results in activation of Hippo pathway effectors Yap/Taz in the granular layer, which subsequently represses cholesterol biosynthesis. Furthermore, the ablation of Yap/Taz partially rescues skin barrier defects. Mechanistically, RIPK4 directly phosphorylates LATS1/2 after recruiting them into liquid condensates. Disease-derived RIPK4 mutants exhibit defects in LATS1/2 activation either due to impaired kinase activity or disrupted phase separation. Our findings demonstrate that a RIPK4-initiated noncanonical Hippo pathway plays a specific role in epidermal differentiation.

PTEN-induced kinase-1 (PINK1) is a crucial player in selective clearance of damaged mitochondria via the autophagy-lysosome pathway, a process termed mitophagy. Previous studies on PINK1 mainly focused on its post-translational modifications, while the transcriptional regulation of PINK1 is much less understood. Herein, we reported a novel mechanism in control of PINK1 transcription by SMAD Family Member 3 (SMAD3), an essential component of the transforming growth factor beta (TGFβ)-SMAD signaling pathway. First, we observed that mitochondrial depolarization promotes PINK1 transcription, and SMAD3 is likely to be the nuclear transcription factor mediating PINK1 transcription. Intriguingly, SMAD3 positively transactivates PINK1 transcription independent of the canonical TGFβ signaling components, such as TGFβ-R1, SMAD2 or SMAD4. Second, we found that mitochondrial depolarization activates SMAD3 via PINK1-mediated phosphorylation of SMAD3 at serine 423/425. Therefore, PINK1 and SMAD3 constitute a positive feedforward loop in control of mitophagy. Finally, activation of PINK1 transcription by SMAD3 provides an important pro-survival signal, as depletion of SMAD3 sensitizes cells to cell death caused by mitochondrial stress. In summary, our findings identify a non-canonical function of SMAD3 as a nuclear transcriptional factor in regulation of PINK1 transcription and mitophagy and a positive feedback loop via PINK1-mediated SMAD3 phosphorylation and activation. Understanding this novel regulatory mechanism provides a deeper insight into the pathological function of PINK1 in the pathogenesis of neurodegenerative diseases such as Parkinson's disease.

OBJECTIVE:Despite the growing evidence supporting the regulatory role of small carboxy-terminal domain (CTD) phosphatase 4 (SCP4) in metabolic pathways, limited knowledge exists concerning its involvement and molecular basis in temporomandibular joint (TMJ) cartilage growth, development, and homeostasis maintenance. Therefore, this study aims to investigate the role of SCP4 in chondrogenesis in condylar cartilage. METHODS:We generated chondrocyte-specific SCP4 conditional knockout mice (SCP4Col2Cre). Whole skeletal staining, ABH/OG or HE staining, and immunohistochemistry were employed to compare chondrocyte differentiation and cartilage development between SCP4Col2Cre and Cre-negative mice during prenatal and postnatal periods. The impact of SCP4 on subchondral bone in mice was assessed using Micro-CT. Additionally, relevant biological functions were evaluated by KEGG and GO enrichment analysis, which further confirmed immunohistochemical staining, Western Blot, RT-PCR and Seahorse experiment. RESULTS:Our findings demonstrated that the deficiency of SCP4 in chondrocytes resulted in defects in condylar chondrogenesis and impaired matrix production. Accordingly, the SCP4Col2Cre mice exhibited a significant decrease in bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), with an increase in trabecular separation (Tb.Sp). Furthermore, RNA-seq analysis showed the impact of SCP4 deficiency on glucose metabolism. Subsequently, we confirmed that the deficiency of SCP4 resulted in aberrant regulation of glucose transporter 1 (Glut1) and other glucose metabolism-related gene expression throughout prenatal and postnatal development in vivo and in vitro. We further demonstrated in vitro that the deletion of SCP4 led to increased ATP production and extracellular acidification rate (ECAR) levels, while concurrently reducing oxygen consumption rate (OCR) levels. CONCLUSION:Our study emphasizes the crucial role of SCP4 in regulating prenatal and postnatal TMJ cartilage development, partly through aberrant upregulation of Glut1-mediated glucose metabolism.

Transforming growth factor β (TGF-β) is well known to play paradoxical roles in tumorigenesis as it has both growth-inhibitory and pro-metastatic effects. However, the underlying mechanisms of how TGF-β drives the opposing responses remain largely unknown. Here, we report that ERBB4, a member of the ERBB receptor tyrosine kinase family, specifically promotes TGF-β's metastatic response but not its anti-growth response. ERBB4 directly phosphorylates Tyr162 in the linker region of SMAD4, which enables SMAD4 to achieve a higher DNA-binding ability and potentiates TGF-β-induced gene transcription associated with epithelial-to-mesenchymal transition (EMT), cell migration, and invasion without affecting the genes involved in growth inhibition. These selective effects facilitate lung cancer metastasis in mouse models. This discovery sheds light on the previously unrecognized role of SMAD4 as a substrate of ERBB4 and highlights the selective involvement of the ERBB4-SMAD4 regulatory axis in tumor metastasis.

EGFR hotspot mutations (mEGFR), including primary L858R, exon 19 deletion, and secondary T790M, are pivotal oncogenic drivers in human non-small cell lung cancer (NSCLC). Meanwhile, NSCLC resistance to third-generation tyrosine kinase inhibitors (TKIs) is a major clinical challenge and remains mechanistically unresolved. Here, we uncover a previously unrecognized immunological mechanism whereby mEGFR exploits cGAS-STING innate immune signaling, conventionally regarded as tumor-suppressive, to sustain oncogenic signaling and therapeutic resistance. Mechanistically, mutant EGFR kinase aberrantly incorporates into STING signalosomes, directly phosphorylating STING (Y245/Y314) and TBK1 (Y577/Y677), stabilizing and hyperactivating TBK1 proteins, and establishing an unexpected and kinase loop critical for DNA damage repair. Disruption of this mEGFR-STING-TBK1 axis, genetically or pharmacologically, profoundly sensitized resistant patient-derived NSCLC organoids to chemotherapy. Combining TBK1 inhibition with cisplatin notably eradicated mEGFR-driven tumors in spontaneous and immunocompetent NSCLC murine models and patient-derived organoids. Our findings suggest a new function of cGAS-STING in the DNA damage repair program, its paradoxical exploitation by oncogenic driver mutations, and an innate immune therapeutic vulnerability in NSCLC.

The rise of food delivery culture has resulted in millions of tons of food-contact plastic containers being used each year, yet the risks of micro(nano)plastics (MNPs) released during the storage of oil-rich foods are still not well understood. Here, we investigated MNP release from polypropylene (PP) and polyethylene (PE)-coated containers under simulated takeout scenarios. When exposed to cooking oil and microwave heating, containers released up to 125-fold more MNPs and 471-fold more heavy metals compared to water exposure, with significantly altered physicochemical properties. Oil-derived PP NPs, uniquely encapsulated in oil films with positive surface charge (+7.37 mV). The positive charge of oil-derived NPs may enhance their interaction with negatively charged cell membranes, leading to rapid cell death within 5 minutes at a concentration of 100 μg/mL through membrane disruption. Transcriptomic analysis revealed that oil-PP NPs triggered substantially more extensive gene expression changes than water-derived NPs, particularly in pathways related to acute cellular stress and mitochondrial energy metabolism. Global exposure assessments highlight annual human intake of up to 3.35 g from oil-rich takeout food. Based on integrated cellular and molecular endpoints, we established a benchmark dose lower limit (BMDL) of 1.18 μg/mL for oil-PP NPs. MNP abundance in human biological samples exceeds BMDL thresholds, suggesting significant health risks. Our findings reveal previously unknown mechanisms of oil-derived MNP toxicity and underscore the urgent need for stricter regulation of plastic food packaging used with oil-rich foods.

Chronic infections with hepatitis E virus (HEV), especially those of genotype 3 (G3), frequently lead to liver fibrosis and cirrhosis in patients. However, the causation and mechanism of liver fibrosis triggered by chronic HEV infection remain poorly understood. Here, we found that the viral multiple-domain replicase (ORF1) undergoes unique ubiquitin–proteasomal processing leading to formation of the H EV- D erived S MAD A ctivator (HDSA), a viral polypeptide lacking putative helicase and RNA polymerase domains. The HDSA is stable, non-HSP90-bound, localizes to the nucleus, and is abundant in G3 HEV-infected hepatocytes of various origins. Markedly, the HDSA in hepatocytes potentiates the fibrogenic TGF-β/SMAD pathway by forming compact complexes with SMAD3 to facilitate its promoter binding and coactivator recruitment, leading to significant fibrosis in HEV-susceptible gerbils. Virus infection–induced liver fibrosis in HEV-susceptible gerbils could be prevented by mutating the residues P989C, A990C, and A991C (PAA-3C) within ORF1, which are required for proteasomal processing. Thus, we have identified a viral protein derived from host proteasomal processing, defined its notable role in liver fibrosis and highlighted the nature of an unanticipated host–HEV interaction that facilitates hepatitis E pathogenesis.

Abstract FAM134/RETREG family members are ER-phagy receptors that maintain cellular homeostasis by regulating endoplasmic reticulum turnover. However, possible non-ER-phagy functions of FAM134 proteins remain elusive. Here, we show that RETREG3/FAM134C functions as a selective autophagy receptor for the type I BMP receptor (BMPRIA/ALK3) and recruits BMPRIA into LC3-containing autophagosomes for subsequent degradation. FAM134C-induced degradation diminishes the availability of BMP receptors and thus the strength of BMP signaling. Inhibition of autophagy through chemical means or knockdown of key autophagy regulators, ATG5 or Beclin-1, prevents BMPR1A degradation. Additionally, disruption of the putative LC3-interacting region (LIR) motif in FAM134C completely abolishes its interaction with LC3, thereby impeding its ability to degrade BMPR1A. Moreover, FAM134C-deficient mice exhibit enhanced BMP responses in the intestines, which affects intestinal crypt regeneration. Our findings suggest that FAM134C acts as a specific receptor that controls BMP signaling through the autophagic degradation of the type I BMP receptor, independent of its canonical role in ER-phagy.

Lysosomal storage disorders (LSDs), which are characterized by genetic and metabolic lysosomal dysfunctions, constitute over 60 degenerative diseases with considerable health and economic burdens. However, the mechanisms driving the progressive death of functional cells due to lysosomal defects remain incompletely understood, and broad-spectrum therapeutics against LSDs are lacking. Here, we found that various gene abnormalities that cause LSDs, including Hexb, Gla, Npc1, Ctsd and Gba, all shared mutual properties to robustly autoactivate neuron-intrinsic cGAS-STING signalling, driving neuronal death and disease progression. This signalling was triggered by excessive cytoplasmic congregation of the dsDNA and DNA sensor cGAS in neurons. Genetic ablation of cGAS or STING, digestion of neuronal cytosolic dsDNA by DNase, and repair of neuronal lysosomal dysfunction alleviated symptoms of Sandhoff disease, Fabry disease and Niemann-Pick disease, with substantially reduced neuronal loss. We therefore identify a ubiquitous mechanism mediating the pathogenesis of a variety of LSDs, unveil an inherent connection between lysosomal defects and innate immunity, and suggest a uniform strategy for curing LSDs.