Centromere pairing is crucial for synapsis in meiosis. This study delves into the Skp1-Cullin1-F-box protein (SCF) E3 ubiquitin ligase complex, specifically focusing on F-box protein 47 (FBXO47), in mouse meiosis. Here, we revealed that FBXO47 is localized at the centromere and it regulates centromere pairing cooperatively with SKP1 to ensure proper synapsis in pachynema. The absence of FBXO47 causes defective centromeres, resulting in incomplete centromere pairing, which leads to corruption of SC at centromeric ends and along chromosome axes, triggering premature dissociation of chromosomes and pachytene arrest. FBXO47 deficient pachytene spermatocytes exhibited drastically reduced SKP1 expression at centromeres and chromosomes. Additionally, FBXO47 stabilizes SKP1 by down-regulating its ubiquitination in HEK293T cells. In essence, we propose that FBXO47 collaborates with SKP1 to facilitate centromeric SCF formation in spermatocytes. In summary, we posit that the centromeric SCF E3 ligase complex regulates centromere pairing for pachynema progression in mice.

Pancreatic cancer (PC) is a challenging and heterogeneous disease with a high mortality rate. Despite advancements in treatment, the prognosis for PC patients remains poor, with a high chance of disease recurrence. Biomarkers are crucial for diagnosing cancer, predicting patient prognosis and selecting treatments. However, the current lack of effective biomarkers for PC could contribute to the insufficiency of existing treatments. These findings underscore the urgent need to develop novel strategies to fight this disease. This study utilized multiple comprehensive bioinformatic analyses to identify potential therapeutic target genes in PC, focusing on histone lysine demethylases (KDMs). We found that high expression levels of KDM family genes, particularly KDM1A, KDM5A and KDM5B, were associated with improved overall survival in the cohort. Furthermore, the infiltration of various immune cells, including B cells, neutrophils, CD8+ T cells, dendritic cells, and macrophages, was positively correlated with KDM1A, KDM5A, and KDM5B expression. Moreover, MetaCore pathway analysis revealed interesting connections between KDM1A and the cell cycle and proliferation, between KDM5A and DNA damage and double-strand break repair through homologous recombination, and between KDM5B and WNT/β-catenin signaling. These findings suggest that KDM1A, KDM5A and KDM5B may serve as promising biomarkers and therapeutic targets for PC, a disease of high importance due to its aggressive nature and urgent need for novel biomarkers to improve diagnosis and treatment.

BACKGROUND: F-box protein 45 (FBXO45) has been implicated in the progression of several diseases. Whether FBXO45 is involved in the development of bladder cancer remains unclear. Thus, this study focused on the effect of FBXO45 on the malignant progression of bladder cancer cells.
METHODS: FBXO45 small-interference fragment was transfected into RT4 and 5637 cells by liposome-mediated transfection, and the knockdown efficiency of FBXO45 was verified by Western blot assay. The growth rate between FBXO45 knockdown cell lines and control cell lines was compared by counting kit 8 and plate cloning experiments. The motility of bladder cancer cells was observed via the Transwell test and Wound healing test. The effects of FBXO45 silencing on apoptosis and cell division were confirmed by flow cytometry. Western blot assay was performed to determine the function of FBXO45 knockdown on key proteins of cell apoptosis and the ERK/Cyclin D1/CDK4 pathway.
RESULTS: After FBXO45 knockdown, the proliferation of bladder cancer cells was blocked (p < 0.01), and the migration and invasion abilities were reduced (p < 0.01). FBXO45 knockdown reduced the number of S-phase cells (RT4, p < 0.01; 5637, p < 0.05) and enhanced the apoptotic rate (p < 0.01). FBXO45 knockdown decreased the levels of p-ERK1/2, CDK4 and Cyclin D1 (p < 0.01).
CONCLUSIONS: This study revealed that FBXO45 plays a carcinogenic role in bladder cancer via the ERK/Cyclin D1/CDK4 pathway, which provides a reference for the clinical treatment of patients with bladder cancer.

The ubiquitin-proteasome system is frequently employed to degrade viral proteins, thereby inhibiting viral replication and pathogenicity. Through an analysis of the degradation kinetics of all the SARS-CoV-2 proteins, our study revealed rapid degradation of several proteins, particularly NSP5. Additionally, we identified FBXO22, an E3 ubiquitin ligase, as the primary regulator of NSP5 ubiquitination. Moreover, we validated the interaction between FBXO22 and NSP5, demonstrating that FBXO22-mediated ubiquitination of NSP5 facilitated its recognition by the proteasome, leading to subsequent degradation. Specifically, FBXO22 catalyzed the formation of K48-linked polyubiquitin chains on NSP5 at lysine residues 5 and 90. Knockdown of FBXO22 resulted in decreased NSP5 ubiquitination levels, increased stability, and enhanced ability to evade the host innate immune response. Notably, the protein level of FBXO22 were negatively correlated with SARS-CoV-2 load, highlighting its importance in inhibiting viral replication. This study elucidates the molecular mechanism by which FBXO22 mediates the degradation of NSP5 and underscores its critical role in limiting viral replication. The identification of FBXO22 as a regulator of NSP5 stability provides new insights and potential avenues for targeting NSP5 in antiviral strategies.

BACKGROUND: Non-small cell lung cancer (NSCLC) is a malignant form of lung cancer, and its prognosis could be improved by identifying key therapeutic targets. Thus, this study investigates the potential role of F-box Only Protein 33 (FBXO33) in NSCLC.
METHODS: The expression levels of FBXO33 in NSCLC were determined using University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN) prediction, and its correlation with overall survival (OS) was analyzed via Kaplan-Meier survival analysis. These results were validated through quantitative polymerase chain reaction (qPCR), western blot (WB), and immunofluorescence (IF). We modulated FBXO33 expression by overexpression or knockdown and analyzed its effects on cell growth, proliferation, migration, invasion, and stemness characteristics in NSCLC cell lines. Additionally, the interaction between FBXO33 and Myelocytomatosis (Myc) and its impact on Myc ubiquitination were examined. An in vivo NSCLC xenograft model was used to corroborate the in vivo experimental results.
RESULTS: The study found an inverse correlation between FBXO33 expression in NSCLC and OS. Lower FBXO33 expression enhanced the growth, proliferation, migration, invasion, and stemness characteristics of NSCLC cell lines. FBXO33 interacted with Myc to promote its ubiquitination and subsequent degradation, which suppressed NSCLC development.
CONCLUSIONS: FBXO33 is expressed at low levels in NSCLC and correlates with lower OS. Overexpression of FBXO33 promotes Myc ubiquitination and degradation and inhibits tumor cell proliferation, migration and stemness characteristics, thereby impeding NSCLC progression.

The circadian clock is an endogenous oscillator, and its importance lies in its ability to impart rhythmicity on downstream biological processes, or outputs. Our knowledge of output regulation, however, is often limited to an understanding of transcriptional connections between the clock and outputs. For instance, the clock is linked to plant growth through the gating of photoreceptors via rhythmic transcription of the nodal growth regulators, PHYTOCHROME-INTERACTING FACTORs (PIFs), but the clock\'s role in PIF protein stability is less clear. Here, we identified a clock-regulated, F-box type E3 ubiquitin ligase, CLOCK-REGULATED F-BOX WITH A LONG HYPOCOTYL 1 (CFH1), that specifically interacts with and degrades PIF3 during the daytime. Additionally, genetic evidence indicates that CFH1 functions primarily in monochromatic red light, yet CFH1 confers PIF3 degradation independent of the prominent red-light photoreceptor phytochrome B (phyB). This work reveals a clock-mediated growth regulation mechanism in which circadian expression of CFH1 promotes sustained, daytime PIF3 degradation in parallel with phyB signaling.

Ribonucleoprotein (RNP) granules are membraneless electron-dense structures rich in RNAs and proteins, and involved in various cellular processes. Two RNP granules in male germ cells, intermitochondrial cement and the chromatoid body (CB), are associated with PIWI-interacting RNAs (piRNAs) and are required for transposon silencing and spermatogenesis. Other RNP granules in male germ cells, the reticulated body and CB remnants, are also essential for spermiogenesis. In this study, we disrupted FBXO24, a testis-enriched F-box protein, in mice and found numerous membraneless electron-dense granules accumulated in sperm flagella. Fbxo24 knockout (KO) mice exhibited malformed flagellar structures, impaired sperm motility, and male infertility, likely due to the accumulation of abnormal granules. The amount and localization of known RNP granule-related proteins were not disrupted in Fbxo24 KO mice, suggesting that the accumulated granules were distinct from known RNP granules. Further studies revealed that RNAs and two importins, IPO5 and KPNB1, abnormally accumulated in Fbxo24 KO spermatozoa and that FBXO24 could ubiquitinate IPO5. In addition, IPO5 and KPNB1 were recruited to stress granules, RNP complexes, when cells were treated with oxidative stress or a proteasome inhibitor. These results suggest that FBXO24 is involved in the degradation of IPO5, disruption of which may lead to the accumulation of abnormal RNP granules in sperm flagella.

Accumulating evidence has demonstrated that F-box protein 22 (FBXO22) participates in tumour development and progression in various types of human malignancies. However, the functions and detailed molecular mechanisms of FBXO22 in osteosarcoma tumorigenesis and progression remain elusive. In this study, we aimed to determine the effects of FBXO22 on the cell proliferation, migration and invasion of osteosarcoma cells using cell counting kit-8 and Matrigel Transwell approaches. Moreover, we explored the molecular mechanisms by which FBXO22 mediated oncogenesis and progression in osteosarcoma via Western blotting, immunoprecipitation and ubiquitination. We found that FBXO22 depletion inhibited the proliferation, migration and invasion of osteosarcoma cells, whereas FBXO22 overexpression increased the proliferation and motility of osteosarcoma cells. Mechanistically, FBXO22 promoted the ubiquitination and degradation of FoxO1 in osteosarcoma cells. FBXO22 depletion reduced cell proliferation and motility via regulation of FoxO1. Taken together, our findings provide new insight into FBXO22-induced osteosarcoma tumorigenesis. The inhibition of FBXO22 could be a promising strategy for the treatment of osteosarcoma.

Pancreatic ductal adenocarcinoma (PDAC) poses a significant threat due to its tendency to evade early detection, frequent metastasis, and the subsequent challenges in devising effective treatments. Processes that govern epithelial-mesenchymal transition (EMT) in PDAC hold promise for advancing novel therapeutic strategies. SAMD1 (SAM domain-containing protein 1) is a CpG island-binding protein that plays a pivotal role in the repression of its target genes. Here, we revealed that SAMD1 acts as a repressor of genes associated with EMT. Upon deletion of SAMD1 in PDAC cells, we observed significantly increased migration rates. SAMD1 exerts its effects by binding to specific genomic targets, including CDH2, encoding N-cadherin, which emerged as a driver of enhanced migration upon SAMD1 knockout. Furthermore, we discovered the FBXO11-containing E3 ubiquitin ligase complex as an interactor and negative regulator of SAMD1, which inhibits SAMD1 chromatin-binding genome-wide. High FBXO11 expression in PDAC is associated with poor prognosis and increased expression of EMT-related genes, underlining an antagonistic relationship between SAMD1 and FBXO11. In summary, our findings provide insights into the regulation of EMT-related genes in PDAC, shedding light on the intricate role of SAMD1 and its interplay with FBXO11 in this cancer type.

Neuroblastoma, the deadliest solid tumor in children, exhibits alarming mortality rates, particularly among high-risk cases. To enhance survival rates, a more precise risk stratification for patients is imperative. Utilizing proteomic data from 34 cases with or without N-Myc amplification, we identified 28 differentially expressed ubiquitination-related proteins (URGs). From these, a prognostic signature comprising 6 URGs was constructed. A nomogram incorporating clinical-pathological parameters yielded impressive AUC values of 0.88, 0.93, and 0.95 at 1, 3, and 5 years, respectively. Functional experiments targeting the E3 ubiquitin ligase FBXO42, a component of the prognostic signature, revealed its TP53-dependent promotion of neuroblastoma cell proliferation. In conclusion, our ubiquitination-related prognostic model robustly predicts patient outcomes, guiding clinical decisions. Additionally, the newfound pro-proliferative role of FBXO42 offers a novel foundation for understanding the molecular mechanisms of neuroblastoma.