TRAF4-Mediated LAMTOR1 Ubiquitination Promotes mTORC1 Activation and Inhibits the Inflammation-Induced Colorectal Cancer Progression

Mapping the Interactome of KRAS and Its G12C/D/V Mutants by Integrating TurboID Proximity Labeling with Quantitative Proteomics

KRAS mutations are major drivers of human cancers, yet how distinct mutations rewire protein interactions and metabolic pathways to promote tumorigenesis remains poorly understood. To address this, we systematically mapped the protein interaction networks of wild-type KRAS and three high-frequency oncogenic mutants (G12C, G12D, and G12V) using TurboID proximity labeling coupled with quantitative proteomics. Bioinformatic analysis revealed mutant-specific binding partners and metabolic pathway alterations, including significant enrichment in insulin signaling, reactive oxygen species regulation, and glucose/lipid metabolism. These changes collectively drive tumor proliferation and immune evasion. Comparative analysis identified shared interactome shifts across all mutants: reduced binding to LZTR1, an adaptor for KRAS degradation, and enhanced recruitment of LAMTOR1, a regulator of mTORC1-mediated growth signaling. Our multi-dimensional profiling establishes the first comprehensive map of KRAS-mutant interactomes and links specific mutations to metabolic reprogramming. These findings provide mechanistic insights into KRAS-driven malignancy and highlight LZTR1 and LAMTOR1 as potential therapeutic targets. The study further lays a foundation for developing mutation-specific strategies to counteract KRAS oncogenic signaling.

Ubiquitination regulation of mitochondrial homeostasis: a new sight for the treatment of gastrointestinal tumors

Mitochondrial homeostasis (MH) refers to the dynamic balance of mitochondrial number, function, and quality within cells. Maintaining MH is significant in the occurrence, development, and clinical treatment of Gastrointestinal (GI) tumors. Ubiquitination, as an important post-translational modification mechanism of proteins, plays a central role in the regulation of MH. Over the past decade, research on the regulation of MH by ubiquitination has focused on mitochondrial biogenesis, mitochondrial dynamics, Mitophagy, and mitochondrial metabolism during these processes. This review summarizes the mechanism and potential therapeutic targets of ubiquitin (Ub)-regulated MH intervention in GI tumors.

Identification of novel Kv1.3 channel-interacting proteins using proximity labelling in T-cells

Potassium channels regulate membrane potential, calcium flux, cellular activation and effector functions of adaptive and innate immune cells. The voltage-activated Kv1.3 channel is an important regulator of T cell-mediated autoimmunity and microglia-mediated neuroinflammation. Kv1.3 channels, via protein-protein interactions, are localized with key immune proteins and pathways, enabling functional coupling between K+ efflux and immune mechanisms. To gain insights into proteins and pathways that interact with Kv1.3 channels, we applied a proximity-labeling proteomics approach to characterize protein interactors of the Kv1.3 channel in activated T-cells. Biotin ligase TurboID was fused to either N or C termini of Kv1.3, stably expressed in Jurkat T cells and biotinylated proteins in proximity to Kv1.3 were enriched and quantified by mass spectrometry. We identified over 1,800 Kv1.3 interactors including known interactors (beta-integrins, Stat1) although majority were novel. We found that the N-terminus of Kv1.3 preferentially interacts with protein synthesis and protein trafficking machinery, while the C-terminus interacts with immune signaling and cell junction proteins. T-cell Kv1.3 interactors included 335 cell surface, T-cell receptor complex, mitochondrial, calcium and cytokine-mediated signaling pathway and lymphocyte migration proteins. 178 Kv1.3 interactors in T-cells also represent genetic risk factors of T cell-mediated autoimmunity, including STIM1, which was further validated using co-immunoprecipitation. Our studies reveal novel proteins and molecular pathways that interact with Kv1.3 channels in adaptive (T-cell) and innate immune (microglia), providing a foundation for how Kv1.3 channels may regulate immune mechanisms in autoimmune and neurological diseases.

HSP70 promotes amino acid-dependent mTORC1 signaling by mediating CHIP-induced NPRL2 ubiquitination and degradation

Mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth and its dysregulation leads to a variety of human diseases. Although NPRL2, an essential component of the GATOR1 complex, is reported to effectively suppress amino acid-induced mTORC1 activation, the regulation of NPRL2 protein stability is unclear. In this study, we show that chaperon-associated ubiquitin ligase CHIP interacts with NPRL2 and promotes its polyubiquitination and proteasomal degradation. Moreover, HSP70 mediates CHIP-induced ubiquitination and degradation of NPRL2. Consistently, overexpression of HSP70 enhances whereas HSP70 depletion inhibits amino acid-induced mTORC1 activation. Accordingly, knockdown of HSP70 promotes basal autophagic flux, and inhibits cell growth and proliferation. Taken together, these results demonstrated that HSP70 is a novel activator of mTORC1 through mediating CHIP-induced ubiquitination and degradation of NPRL2.

Exploring the role of aggrephagy-related signatures in immune microenvironment, prognosis, and therapeutic strategies of breast cancer

Breast cancer (BC) is 1 of the most common malignant tumors among women globally. This study aimed to develop a prognostic signature based on aggrephagy-related genes (ARGs). Transcriptomic and clinical data for BC patients were downloaded from the cancer genome atlas and GEO databases. Differential expression analysis, univariate Cox proportional hazards regression and least absolute shrinkage and selection operator Cox regression were employed to construct a prognostic signature. Consensus clustering, evaluation of immune infiltration and drug sensitivity, and gene set enrichment analysis, and development of nomogram were performed. The expression of ARGs was validated using data from the Cancer Cell Line Encyclopedia and clinical samples. Eleven ARGs were abnormally expressed in BC, with 5 showing significant correlations with BC prognosis. Consensus clustering identified 2 molecular subtypes with distinct prognoses. A prognostic signature including 5 ARGs (VIM, TUBB1, TUBA3E, TUBA3D, TUBA1C) was developed, which showed high performance in predicting BC prognosis. The low-risk group showed enrichment in extracellular matrix organization and cell migration processes while chromosome separation was suppressed. Additionally, patients in this group also show activation in several signaling pathways including MAPK, PI3K-AKT, and cAMP pathways, whereas cell cycle and neutrophil extracellular trap formation were significantly inhibited. The signature was also associated with immune infiltration and drug sensitivity. A nomogram incorporating the risk signature, clinical stage and chemotherapy was constructed, demonstrating excellent performance in predicting prognosis. The expression of signature-related genes were validated in patients with BC. This study successfully constructed molecular subtypes and a prognostic signature based on ARGs in BC, and developed a nomogram.

Whole-Transcriptome Analysis Reveals Potential CeRNA Regulatory Mechanism in Takifugu rubripes against Cryptocaryon irritans Infection

Cryptocaryon irritans (C. irritans) is a proto-ciliate parasite that infects marine fishes, including the cultured species Takifugu rubripes (T. rubripes), causing disease and potential mortality. In host organisms, infection by parasites triggers an immune response that is modulated by regulatory elements including proteins and non-coding RNAs. In this study, the whole transcriptome RNA sequencing of T. rubripes gill tissue before and after infection with C. irritans was performed to reveal the competitive endogenous RNA (ceRNA) regulatory network. Histomorphology revealed gill segment swelling and parasitic invasion in the infected group. The analysis identified 18 differentially expressed miRNAs (DEMs), 214 lncRNAs (DELs), 2501 genes (DEGs), and 7 circRNAs (DECs) in the infected group. Gene Ontology (GO) enrichment analysis revealed that these genes were notably enriched in the Wnt signaling pathway and mTOR signaling pathway. The co-expression networks (lncRNA/circRNA-miRNA-mRNA) were constructed based on correlation analysis of the differentially expressed RNAs. Further analysis suggested that the LOC105418663-circ_0000361-fru-miR-204a-fzd3a ceRNA axis was potentially involved in the regulation of immune responses against C. irritans infection. Finally, the expression levels of DEG, DEL, and DEM were validated. This study reveals the regulatory mechanism of a candidate ceRNA network, providing insights into the potential mechanism of T. rubripes' infection with C. irritans.