Apoptosis is regulated by Bcl-2 family of proteins through direct binding interactions at the mitochondrial outer membrane. Bak, a key cellular executioner protein in this family, differs from the other executioner proteins Bax and Bok in that it is constitutively localized at the mitochondrial outer membrane via its C-terminal sequence (CTS). Binding of the BH3-only protein Bim triggers conformational changes in Bak that lead to oligomerization and mitochondrial membrane permeabilization. However, the molecular mechanism by which Bim activates Bak remains incompletely understood. Here we demonstrate both in vitro and in cells, that efficient Bim-mediated activation of Bak requires not only the binding of the BH3-motif of Bim to the canonical BH3-binding groove of Bak, but also sequence specific, direct binding of the Bim-CTS to the Bak-CTS. These findings reveal an unexpected contribution of the Bak-CTS to the molecular control of Bak activation during apoptosis.
Renal cell carcinoma (RCC) is a highly heterogeneous malignancy characterized by diverse molecular alterations and dynamic evolutionary trajectories. Advances in genomics and molecular profiling have shifted RCC management from morphology-based classification toward molecularly informed diagnosis and therapy. In this review, we integrate recent multi-omics and clinical advances to define the evolving biological and therapeutic landscape of RCC. We highlight how the 2022 WHO classification incorporates molecular features to refine pathological subtyping and summarize key driver genetic alterations underlying major RCC entities. We then discuss insights derived from multi-region sequencing studies, including TRACERx Renal, which demonstrate how intratumoral heterogeneity, branched evolution, and clonal selection shape disease progression and therapeutic resistance. We further examine subtype-specific metabolic programs, with particular emphasis on dysregulation of the AMPK-mTORC1 signaling axis and distinct metabolic dependencies across clear cell and non-clear-cell RCC. We additionally highlight cell death regulation and differentiation plasticity as integrative themes that connect molecular pathogenesis to therapeutic vulnerability, with sarcomatoid and rhabdoid dedifferentiation as a key example. Finally, we review the evolution of systemic therapies, from VEGF-targeted tyrosine kinase inhibitors to immune checkpoint-based combinations, and outline emerging strategies, including HIF-2α inhibition, PD-1/VEGF bispecific antibodies, and subtype-specific metabolic and epigenetic dependencies. Collectively, this review provides an integrated framework linking molecular evolution, metabolic reprogramming, and therapeutic development, with the goal of advancing biomarker-driven precision management in RCC.
Perioperative neurocognitive disorders (PND) are common neurological complications in elderly surgical patients, for which effective mechanism-based therapies remain lacking. This study identifies ferroptosis, an iron-dependent lipid peroxidation-driven cell death, as a key pathological process in PND, and pharmacological inhibition of ferroptosis with ferrostatin-1 significantly ameliorated cognitive deficits in a surgery and anesthesia-induced mouse model of PND. Moreover, accumulation of glutamate has been observed in the brains of PND mice, which competitively inhibits the neuronal cystine/glutamate antiporter system Xc- (via SLC7A11) to trigger glutathione depletion and ferroptotic cell death. Excessive glutamate production and release are driven by hyperexpression of glutamate-producing enzyme glutaminase 1 (GLS1) in activated microglia via STAT1-dependent transcriptional activation. Pharmacological inhibition of GLS1 with the selective inhibitors CB839 and BPTES suppressed ferroptosis, preserved synaptic plasticity, and improved cognitive performance in PND mice, indicating GLS1 as a potential therapeutic target of PND. Notably, elevated plasma GLS1 levels in PND patients correlated negatively with cognitive test scores (R2 = 0.479, p < 0.001) and exhibited moderate diagnostic value across two independent cohorts (AUCs = 0.77 and 0.84), underscoring its clinical relevance as a potential biomarker. Collectively, our findings establish microglial GLS1 as a critical mediator of ferroptosis in PND and highlight its dual promise as a therapeutic target and diagnostic indicator.
Aberrant tumor metabolism plays a crucial role in establishing and sustaining an immunosuppressive microenvironment. CD73, a key enzyme in the purine metabolism pathway, is frequently overexpressed in tumors, leading to elevated extracellular adenosine (ADO) levels. This accumulation suppresses antitumor immune responses by promoting immune cell exhaustion, ultimately contributing to immunotherapy resistance. However, the mechanisms underlying CD73 upregulation in tumors remain poorly defined. Here, we identify aurora kinase B (AURKB) as a critical regulator of CD73 overexpression in renal cell carcinoma (RCC), orchestrating immune evasion and resistance to immune checkpoint therapy. AURKB is highly expressed in RCC, with its prognostic significance being especially evident in tumors with strong immunogenicity. Mechanistically, AURKB enhances CD73 expression, thereby promoting T cell dysfunction and immune suppression. Mass cytometry (CyTOF) analysis revealed that AURKB inhibition facilitates immune infiltration and alleviates immune exhaustion. We further demonstrate that AURKB directly interacts with CD73 and phosphorylates it at serine 429, which inhibits STUB1-mediated ubiquitination and proteasomal degradation of CD73. Targeting AURKB to modulate the post-translational stability of CD73 restores antitumor immunity and synergizes with immune checkpoint blockade in vivo. Collectively, this study uncovers a previously unrecognized AURKB-CD73 axis and provides a mechanistically informed strategy to enhance immunotherapy efficacy in RCC.
Lipocalin-2 (LCN2) has been implicated in the pathogenesis of sepsis-associated encephalopathy (SAE). Our previous work demonstrated a significant increase in astrocyte-derived LCN2 in the hippocampal region during SAE. Notably, this elevated expression strongly correlates with neuronal loss and cognitive impairment, although the underlying mechanisms remain elusive. In our study, we demonstrate that increased secretion of LCN2 from hippocampal astrocytes in SAE mice binds to the neuronal receptor 24p3R, thereby inducing neuronal damage. Notably, the downregulation of neuronal 24p3R effectively abolished the detrimental effects of LCN2. In both lipopolysaccharide (LPS)- and cecal ligation and puncture (CLP)-induced sepsis models in C57 mice, neuronal 24p3R knockdown similarly alleviated sepsis-induced synaptic dysfunction and cognitive deficits. Moreover, elevated brain LCN2 levels during sepsis coincided with suppressed autophagy. Mechanistic studies revealed that LCN2-24p3R axis activated the neuronal mTOR-ULK1 pathway, leading to inhibition of autophagy. Importantly, the inhibition of neuronal mTOR activity restored autophagy and ameliorated mitochondrial damage and neuronal loss caused by astrocyte-derived LCN2. These findings suggest an etiopathogenic mechanism of SAE, which is initiated by the increased astrocytic secretion of LCN2, acting on neuronal 24p3R to activate the mTOR-ULK1 pathway, suppress autophagy, and promote mitochondrial dysfunction and neuronal loss, ultimately driving SAE progression. This study provides novel insights into the molecular mechanisms of astrocyte-neuron communication in SAE and identifies potential therapeutic targets for effective intervention.
The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of the cellular antioxidant response that defends against ferroptosis and facilitates tumour development. Here, by performing an aldehyde dehydrogenase (ALDH) family shRNA screen, our study identifies aldehyde dehydrogenase 3 family member A2 (ALDH3A2) as a potent NRF2 activator that inhibits ferroptosis. Interestingly, ALDH3A2 efficiently activates NRF2 in both wild-type (WT) Kelch-like ECH-associated protein 1 (KEAP1) and mutant KEAP1 tumour cells. Mechanistically, ALDH3A2 inhibits the phosphorylation of glycogen synthase kinase 3 beta (GSK3β) and blocks recruitment of E3 ubiquitin ligase beta-transducin repeat-containing protein (BTRC) to NRF2, thereby stabilizing NRF2 by preventing its proteasomal degradation. Knockdown of ALDH3A2 significantly promotes the activation of the GSK3β signaling pathway and accelerates NRF2 degradation. ALDH3A2 stabilizes NRF2 independently of its enzymatic activity, as enzymatic inactivation of ALDH3A2 fails to block ALDH3A2-mediated NRF2 activation and ferroptosis suppression both in vitro and in vivo. Taken together, our study reveals a novel NRF2 regulatory pathway and suggests ALDH3A2 as a promising druggable target for KEAP1-mutant tumours.
Effector regulatory T (eTreg) cells are indispensable for maintaining peripheral immune tolerance and can also interfere with antitumor immunity. However, how epigenetic modifications regulate eTreg differentiation and peripheral maintenance remains largely unknown. Here, we identify the histone deubiquitinating enzyme Bap1 as a pivotal regulator of eTreg cell fate via its H2A deubiquitination activity. Treg-specific deletion of Bap1 markedly impairs eTreg differentiation and promotes ferroptosis through two phases, culminating in a fatal systemic autoimmune syndrome. In the differentiation phase, Bap1 drives the resting Treg (rTreg)-to-eTreg transition by orchestrating metabolic reprogramming through H2AK119 deubiquitination-mediated activation of Stat5, mTORC1, and OXPHOS signaling pathways. In the maintenance phase, Bap1 protects eTreg from ferroptosis through the GSH-Gpx4 axis and MUFA-mediated lipid metabolism. Yy1 interacts with Bap1 at specific genomic loci to regulates the pathways responsible for eTreg differentiation and resistance to ferroptosis. Finally, acute ablation of Bap1 in Treg cells enhances antitumor immunity by disrupting intratumoral eTreg survival and remodeling the tumor microenvironment. Collectively, our findings identify Bap1 as a key epigenetic-metabolic integrator that governs eTreg cell fate to maintain immune tolerance and restrains antitumor immunity. Schematic overview of the mechanism by which Bap1-mediated deubiquitination determines immune tolerance and anti-tumor immunity by modulating eTreg cell differentiation and ferroptosis. Created with BioRender.com. Created in BioRender. Liu, H. (2026) https://BioRender.com/5f76yo3 .
β-catenin plays a pivotal role in oncogenesis through its involvement in cell-cell adhesion, Wnt signaling, and transcriptional regulation. Dysregulation of β-catenin contributes to tumorigenesis by promoting proliferation, bypassing senescence, and enhancing migration and invasion. In melanoma, however, its role has been controversial, with studies reporting conflicting effects on proliferation, metastasis, and patient survival. Here, we demonstrate that activation of β-catenin is associated with a poor prognosis in melanoma. This conclusion is based on immunohistochemical analysis of a cohort of 157 patients and the identification of a genetic signature for melanoma upon β-catenin activation. This signature includes known targets such as APCDD1 and AXIN2, as well as previously unknown targets like MICAL2 and SLC1A5. Notably, MICAL2 (Molecule Interacting with CasL 2) emerged as a key regulator of the invasive phenotype, with high expression levels correlating with adverse outcomes. Functional studies confirmed that MICAL2 is transcriptionally regulated by β-catenin. Nras and Braf mouse melanoma models further validated the conserved regulation of MICAL2 by β-catenin, linking it to melanoma initiation and metastasis. Moreover, MICAL2 expression is enriched in melanoma cells resistant to BRAF inhibitors, and MICAL2 downregulation restores therapeutic sensitivity. These findings highlight MICAL2 as a central effector of β-catenin signaling and a mediator of melanoma progression and resistance. Given the therapeutic challenges of directly targeting β-catenin, inhibiting the enzymatic activity of MICAL2 offers a promising and innovative strategy to improve outcomes in β-catenin-driven melanoma.
Osteoporosis is a chronic disease driven by an imbalance between bone-building osteoblasts and bone-resorbing osteoclasts, whose hyperactivation can promote this condition. Osteoclasts are multinucleated cells, and their activity directly correlates with their ploidy level. Multinucleation associates with the accumulation of extra centrosomes that can activate the PIDDosome pathway. Depending on cell type, this can lead to a p53/p21-mediated cell cycle arrest, or BCL2-regulated apoptosis. Here, we report that the PIDDosome controls polyploidization in osteoclasts and its absence triggers bone erosion in mice. PIDDosome activation in osteoclasts depends on the presence of extra centrosomes bearing the distal appendage protein ANKRD26. Consistently, loss of Ankrd26 phenocopies PIDDosome-deficiency in osteoclasts. Surprisingly, p53 and p21, which restrict cell cycle progression in the presence of extra centrosomes, are not involved in limiting osteoclast polyploidization and function. In support of this notion, bones from p53-/- mice display a higher trabecular bone mass phenotype, and osteoclasts generated from p21-/- mice show normal OC ploidy and function. Altogether, we document that the PIDDosome regulates bone homeostasis by regulating osteoclast polyploidization and their bone-resorbing function independently of the canonical p53/p21 axis, hinting towards unknown downstream effectors. We propose that modulation of PIDDosome activation might be therapeutically exploited for osteoporosis treatment, while its inhibition may ameliorate osteopetrosis symptoms.
A strong crosstalk exists between endoplasmic reticulum (ER) stress and synovitis. Beyond their canonical role in protein folding, ER stress chaperones may promote inflammation, cell survival, and fibroblast activation under pathological conditions. This study aimed at localizing and quantifying 11 ER stress proteins (BiP, HYOU1, MANF, PDIA4, GANAB, HSP90B1, TXNDC5, DNAJB11, LMAN1, ERP29, CALR) in human inflamed synovial membranes and at investigating their expression in fibroblast-like synoviocytes (FLS) under ER stress, pro-inflammatory, or pro-fibrotic stimuli. By immunohistochemistry, on a first cohort of formalin-fixed paraffin-embedded (FFPE) biopsies obtained from patients with osteoarthritis (OA), chronic pyrophosphate arthropathy (CPPA), and rheumatoid arthritis (RA), these ER chaperones were primarily localized to the lining in low-grade inflammation (Tak <4) and expanded to the sublining under high inflammatory conditions (Tak ≥4), with a widespread distribution in RA. Imaging mass cytometry, applied to a second cohort of FFPE tissue samples collected from patients diagnosed with OA and RA, revealed the co-expression of ER stress proteins with CD55⁺ FLS in the lining and their progressive infiltration into the sublining along with CD34⁺CD31- FLS during inflammation. These observations were confirmed by immunofluorescence on a larger cohort of OA patients. As inflammation progresses, there is a loss of co-expression with CD55 in the lining, accompanied by a gradual shift towards co-expression with CD34 in the sublining. In vitro, ER stress proteins, particularly BiP, HYOU1, MANF, PDIA4, HSP90B1, LMAN1, CALR, and DNAJB11 are overexpressed in human OA FLS following ER stress, pro-inflammatory or pro-fibrotic stimulation, with BiP, PDIA4, HSP90B1, ERP29, and CALR also being secreted. PDIA4 emerged as a central player: its depletion significantly impaired FLS proliferation and migration, highlighting a direct role in driving synovitis. This study provides the first spatial and functional characterization of ER chaperones in human arthritic synovium, linking ER stress to fibroblast plasticity, inflammation, and fibrosis.
Metastatic colorectal cancer (mCRC) is one of the deadliest cancers with very poor response to immune checkpoint blockade (ICB). Standard therapies employ chemotherapy combined with epidermal growth factor receptor (EGFR) blocking antibodies, which are only effective in a fraction of patients with RAS/RAF wild-type tumours. We have previously shown that EGFR deletion in myeloid cells of CRC, rather than in the cancer cells themselves, reduces tumour growth. Here, we investigate to which extent EGFR blockade in myeloid cells increases anti-tumour immunity, thus sensitising CRC to ICB. Using a syngeneic preclinical CRC liver metastasis model based on the transplantation of murine RAS mutant CRC organoids into mice lacking EGFR in myeloid cells, we observe a reduction in metastasis development accompanied by increased intratumoural T-cell infiltration. Importantly, we demonstrate that EGFR deletion reduces the capacity of granulocytic myeloid-derived suppressor cells (G-MDSCs) to suppress CD4+ T-cell proliferation. RNA-seq analysis of sorted MDSCs and T-cells uncovered an EGFR-dependent signature involved in immunosuppression, which in proficient-mismatch-repair (pMMR) CRC patients is associated with worse overall survival. Therapeutically, lifting immunosuppression by EGFR deletion in myeloid cells sensitised tumours to anti-PD-L1 treatment, thus preventing liver metastasis development. These results imply that anti-EGFR therapies combined with ICB might be successful in preventing metastasis of RAS mutated CRC with high infiltration of suppressive EGFR+ myeloid cells.
Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe conditions lacking specific pharmacological treatments. Endoplasmic reticulum (ER) stress plays a pivotal role in their pathophysiology, yet the precise regulatory mechanisms remain elusive. In this study, we identify the E3 ubiquitin ligase ring finger protein 5 (RNF5) as a critical driver of ALI/ARDS. RNF5 is markedly upregulated in response to ALI and significantly exacerbates lung injury by stabilizing HSPA5 (heat shock protein family A member 5), a master regulator of the unfolded protein response (UPR). Notably, in vivo Rnf5 ablation effectively attenuated pulmonary edema, inflammatory cell infiltration, and apoptosis, whereas lung-specific Rnf5 overexpression worsened inflammation and cell death in mice. Mechanistically, RNF5 interacts with HSPA5 and competitively blocks its binding to PERK, facilitating PERK release. Furthermore, RNF5 promotes the retro-translocation of HSPA5 from the ER lumen to the cytosol. In the cytosol, RNF5 mediates the K6- and K63-linked polyubiquitination of HSPA5, enhancing its thermal stability and preventing its re-entry into the ER. This spatial sequestration sustains the persistent dissociation of the PERK-HSPA5 complex, leading to the hyperactivation of the pro-apoptotic and pro-inflammatory PERK-eIF2α-CHOP signaling cascade. The ability of RNF5 to promote ALI is strictly dependent on its E3 ligase activity. In conclusion, our findings uncover a compartment-specific regulatory mechanism of HSPA5, suggesting that the RNF5-HSPA5-PERK axis represents a promising therapeutic target for ALI/ARDS.
Pancreatic β-cell failure in diabetes is driven by chronic inflammation, yet how metabolic stress determines pro-inflammatory cell fate remains unclear. Here, we report that sublethal oxidative stress activates a β-cell-enriched epigenetic switch that licenses intrinsic inflammation. We identify a β-cell-enriched vulnerability wherein oxidative stress disrupts mitochondrial NAD⁺/acetyl-CoA flux, skewing the nuclear equilibrium between the deacetylase SIRT1 and acetyltransferases p300/CBP. This metabolic-epigenetic imbalance induces hyperacetylation of the alarmin HMGB1 at K96/K128-a modification remarkably prominent in β-cells compared to macrophages or hepatocytes. This site-specific acetylation acts as a molecular gate for HMGB1 nucleocytoplasmic translocation, triggering TLR/RAGE-mediated inflammation. Simultaneously, we discover that oxidative stress co-opts the mechanosensitive Hippo pathway, which sequesters YAP to transcriptionally repress SIRT1, thereby forming a functionally integrated signalling axis that exacerbates HMGB1 acetylation. Therapeutically, reconstruction of mitochondrial retrograde signalling via NAD⁺ supplementation (e.g., NMN) or dual inhibition of mitochondrial ROS and Hippo signalling restored acetylation homeostasis and suppressed HMGB1-driven inflammation. Notably, this combinatorial targeting demonstrates greater efficacy than either intervention alone (~73% reduction in inflammatory markers) in mitigating β-cell failure across murine and porcine models. Further validation in non-human primates was specifically implemented to address the unique translational gap of rodent models and available human single-cell datasets: by leveraging human-like islet anatomy and systemic physiological microenvironment, we verified the pharmacodynamic robustness and in vivo feasibility of this strategy in a clinically recapitulative large-animal setting, rather than merely confirming cross-species molecular concordance. Our work unveils a stress-responsive signalling network in which metabolic and mechanical cues are integrated at the epigenetic level to control the inflammatory fate of β-cells, providing a new mechanistic framework for diabetic pathogenesis and a rationale for combinatorial therapeutic intervention. Oxidative stress triggers mitochondrial dysfunction in pancreatic β-cells, depleting NAD⁺ and accumulating acetyl-CoA. This metabolic crisis skews the SIRT1/p300 balance, inducing β-cell-enriched hyperacetylation of HMGB1 at K96/K128-a molecular switch for its nucleocytoplasmic translocation, which activates TLR/RAGE-mediated intrinsic inflammation. Concurrent Hippo pathway activation further exacerbates this process by repressing SIRT1, forming an integrated signaling axis. To ensure reproducibility, we define a minimal validation workflow using β-TC-6 cells or primary islets under standardized sublethal stress. The central mechanism can be verified by monitoring HMGB1 K96/K128 acetylation and nucleocytoplasmic translocation, while the inflammatory cascade can be effectively blunted through modular rescue approaches, including NAD+ supplementation (NMN), mitochondrial ROS inhibition or hippo pathway inhibition.
Though inhibiting the RBPJ transcription complex reduces PD-L1 expression and alleviates T cell dysfunction in hepatocellular carcinoma (HCC), the tumor immunomodulatory function of RBPJ in T cells is unclear. This study used patient-derived xenograft models to illustrate the role of RBPJ disruption in clinical outcomes and sensitivity to immunotherapy. Immunoprecipitation was performed to identify whether HUWE1 is the E3 ubiquitin ligase for RBPJ. CUT&Tag, ChIP-/ATAC-qPCR, flow cytometry, and CyTOF were used to investigate the molecular mechanism of how RBPJ regulated the function of HCC-infiltrating T cells. Mice with conditional knockout or knock-in of Huwe1 or Rbpj in T cells were used to evaluate their role in the tumor growth. Furthermore, virtual screening, molecular dynamics simulation, immunoprecipitation, and DNA pull-down assays revealed the role of acarbose in RBPJ transcription complex. Our study found that RBPJ expression rose in exhausted T cells, aggravating their exhaustion. Mechanistically, HUWE1 facilitated the K341 ubiquitination of RBPJ through K48 linkage. RBPJ contributed to T cell exhaustion by enhancing the transcription of exhaustion-related genes as a transcription factor, recruiting RUVBL1 to elevate H3K4me3 levels on the promoters of exhaustion-related genes or H3K27ac on their enhancers, and induced the transcription of the KMT2C, thereby increasing H3K4me1 levels on the enhancers of exhaustion-related genes. Furthermore, acarbose-induced damage in the RBPJ transcriptional complex indicated that targeting T cell exhaustion may be a promising HCC treatment. Collectively, our research results indicated that inhibiting the RBPJ in T cells changed the tumor microenvironment from “cold” to “hot”.
The oncoprotein MDM2 is widely recognized as the principal negative regulator of p53, thereby controlling the expression of numerous RNA polymerase II (Pol II)-dependent genes involved in cell cycle arrest and apoptosis. Beyond this canonical role, MDM2 also engages in transcriptional regulation independently of p53, for instance through interactions with polycomb repressor complexes. Here, we identify RNA polymerase III (Pol III) as an additional target of MDM2 function. Using two complementary chemical tools-a small-molecule MDM2 antagonist (MI-1061) that releases p53 and augments MDM2 expression, and a PROTAC degrader (MD-224) that simultaneously activates p53 and promotes MDM2 ubiquitination and proteasomal destruction-we dissected the role of MDM2 in cells with amplified MDM2. Elevated MDM2 suppressed the transcription of Pol III-dependent genes encoding tRNA or 5S ribosomal RNA. Mechanistically, we found the aminoterminal domain of MDM2 associated with the catalytic subunit of Pol III, revealing a molecular link between MDM2 and the Pol III machinery. Because Pol III also acts as a cytosolic DNA sensor that converts DNA into double-stranded RNA to trigger RIG-I-TBK1-IRF3-dependent signaling, we asked whether MDM2 modulates this pathway. Indeed, enhanced MDM2 expression markedly attenuated the induction of innate immunity genes such as CXCL10, OAS1, and MX1 following transfection with poly(dA:dT). Similarly, DNA damage induced by a radiomimetic agent activated Pol III-dependent innate signaling, and this was again blunted by high MDM2 levels, resulting in enhanced cell survival. Taken together, our findings establish MDM2 as a previously unrecognized suppressor of Pol III-dependent transcription in response to cytosolic DNA. This expands the repertoire of MDM2 functions beyond repression of p53 and Pol II activity, positioning MDM2 as a broad regulator of transcription and innate immunity.
SUMOylation is characterized as a ubiquitin-like post-translational modification that exhibits mechanistic similarities with ubiquitination. Importantly, it modulates the ubiquitination levels of some target proteins, thereby influencing protein stability. Dysregulation of this modification pathway plays a pivotal role in the pathogenesis and progression of various tumors. While recent studies have demonstrated that protein SUMOylation regulates tumor progression, the specific function and mechanism of Ran-binding protein 2 (RanBP2), an E3 SUMO ligase, remain to be elucidated in lung adenocarcinoma (LUAD). This study demonstrates that RanBP2 exhibits elevated expression in LUAD and correlates with poor prognosis. Functionally, RanBP2 inhibits ferroptosis and enhances the growth of LUAD cells. Mechanistically, RanBP2 augments the SUMOylation of E3 ubiquitin ligase leucine-rich repeat and sterile alpha motif-containing protein 1 (LRSAM1), facilitating its subsequent degradation in the ubiquitin-proteasome pathway, thereby reducing SLC7A11 degradation. The stabilized SLC7A11 protein suppresses ferroptosis and promotes LUAD cell growth. The identified RanBP2 inhibitor, amodiaquine (AQ), in combination with ferroptosis inducer sulfasalazine (SAS), effectively triggered ferroptosis and suppressed LUAD cell growth in vitro and in vivo. This combination enhanced T-cell infiltration and improved anti-PD-1 immunotherapy efficacy. The research identifies a novel RanBP2-LRSAM1-SLC7A11 axis that promotes ferroptosis resistance and LUAD progression. The combination of AQ and SAS represents a promising therapeutic strategy for LUAD.
Telomeres, coated by the shelterin complex, prevent end-to-end fusions and aberrant DNA repair, yet how telomere-binding proteins coordinate chromatin remodeling during the DNA damage response remains unclear. Here we show that the telomeric protein TRF1 is phosphorylated at serine 11 (S11) in response to DNA double-strand breaks, a modification that enhances cellular resistance to DNA damage. We found that CDK2 directly mediates this phosphorylation, which triggers recruitment of the histone methyltransferase SETD5 to telomeric chromatin. SETD5-dependent deposition of H3 trimethylation at lysine 36 (H3K36me3) promotes local chromatin decompaction and enables subsequent recruitment of the phosphatase PPP4C to dephosphorylate γH2AX. Loss of TRF1 S11 phosphorylation results in persistent γH2AX foci, delayed DNA repair, and compromised telomere integrity. Our results define a CDK2-TRF1-SETD5-PPP4C signaling axis that orchestrates phosphorylation-dependent chromatin remodeling at telomeres to ensure genome maintenance during DNA damage stress.
Mitochondria are semi-autonomous organelles whose functions critically depend on nucleus-encoded proteins. TOM40 is the core β-barrel protein of the translocase of the outer mitochondrial membrane (TOM) complex that mediates the import of most nucleus-encoded mitochondrial proteins. Here, we show that the small GTPase RAB32 facilitates the mitochondrial localization of TOM40 and the mitochondrial protein homeostasis in non-small cell lung cancer (NSCLC) cells. Accordingly, knockout of RAB32 results in mitochondrial dysfunction and inhibits NSCLC progression in xenograft and autochthonous NSCLC mouse models. We further identify ubiquitin-specific peptidase 13 (USP13) that removes the K48-linked polyubiquitin chains from RAB32 to prevent its proteasomal degradation. Consistently, knockout of USP13 causes destabilization of RAB32, impairs TOM40 mitochondrial localization and mitochondrial function, and inhibits NSCLC progression, which are restored by reconstitution of wild-type USP13 or RAB32, but not the catalytically inactive USP13C345A/M664/739E. Our study has revealed a previously uncharacterized RAB32-USP13 axis for mitochondrial functions and NSCLC progression.
