Ubiquitin signaling in cell cycle control and tumorigenesis

Mitochondria- and endoplasmic reticulum-localizing iridium(III) complexes induce immunogenic cell death of 143B cells

Recent breakthroughs in cancer immunology have propelled immunotherapy to the forefront of cancer research as a promising treatment approach that harnesses the body's immune system to effectively identify and eliminate cancer cells. In this study, three novel cyclometalated Ir(III) complexes, Ir1, Ir2, and Ir3, were designed, synthesized, and assessed in vitro for cytotoxic activity against several tumor-derived cell lines. Among these, Ir1 exhibited the highest cytotoxic activity, with an IC50 value of 0.4 ± 0.1 μM showcasing its significant anticancer potential. Detailed mechanistic analysis revealed that co-incubation of Ir1 with 143B cells led to Ir1 accumulation within mitochondria and the endoplasmic reticulum (ER). Furthermore, Ir1 induced G0/G1 phase cell cycle arrest, while also diminishing mitochondrial membrane potential, disrupting mitochondrial function, and triggering ER stress. Intriguingly, in mice the Ir1-induced ER stress response disrupted calcium homeostasis to thereby trigger immunogenic cell death (ICD), which subsequently activated the host antitumor immune response while concurrently dampening the in vivo tumor-induced inflammatory response.

Proteome and ubiquitinome analyses of the brain cortex in K18-hACE2 mice infected with SARS-CoV-2

Clinical research indicates that SARS-CoV-2 infection is linked to several neurological consequences, and the virus is still spreading despite the availability of vaccinations and antiviral medications. To determine how hosts respond to SARS-CoV-2 infection, we employed LC-MS/MS to perform ubiquitinome and proteome analyses of the brain cortexes from K18-hACE2 mice in the presence and absence of SARS-CoV-2 infection. A total of 8,024 quantifiable proteins and 5,220 quantifiable lysine ubiquitination (Kub) sites in 2023 proteins were found. Glutamatergic synapse, calcium signaling pathway, and long-term potentiation may all play roles in the neurological consequences of SARS-CoV-2 infection. Then, we observed possible interactions between 26 SARS-CoV-2 proteins/E3 ubiquitin-protein ligases/deubiquitinases and several differentially expressed mouse proteins or Kub sites. We present the first description of the brain cortex ubiquitinome in K18-hACE2 mice, laying the groundwork for further investigation into the pathogenic processes and treatment options for neurological dysfunction following SARS-CoV-2 infection.

Titanium Dioxide Nanoparticles Induce Cell Cycle Arrest and Apoptosis through Inhibiting PI3K/AKT/mTOR Pathway in Spermatogonia

Titanium dioxide nanoparticles (TiO2 NPs) can result in the reduction of sperm numbers, but the mechanisms have not been well elucidated. The purpose of this study was to investigate the effects of TiO2 NPs on cell cycle and apoptosis in spermatogonia and to explore the role of PI3K/AKT/mTOR signaling pathway in this process. The mouse spermatogonia cell line (GC-1) was treated with TiO2 NPs at different concentrations (0, 25, 50, 75 and 100 μg/mL) for 24 h to detect cell viability, cell cycle, apoptosis, and key proteins related to cell cycle and PI3K/AKT/mTOR signaling pathway. The agonist (IGF-1) and inhibitor (LY294002) of PI3K were used to verify the role of PI3K/AKT/mTOR signaling pathway in cell cycle and apoptosis. TiO2 NPs significantly inhibited cell proliferation, induced cell cycle arrest at G0/G1 phase and resulted in apoptosis. TiO2 NPs downregulated the levels of cyclin-dependent kinases (CDKs) and cyclins, including CDK4, CDK2, Cyclin D1 and Cyclin E1, while upregulated the levels of p21 and p53 proteins. Furthermore, TiO2 NPs inhibited the PI3K/AKT/mTOR signaling pathway by decreasing the levels of p-PI3K, p-AKT and p-mTOR. IGF-1 reversed the G0/G1 phase arrest and apoptosis caused by TiO2 NPs. However, LY294002 aggravated the G0/G1 phase arrest and apoptosis resulting from TiO2 NPs. Collectively, TiO2 NPs induced cell cycle arrest at G0/G1 phase and apoptosis through inhibiting the activation of PI3K/AKT/mTOR pathway, which could be the main reason for the reduction in sperm numbers caused by TiO2 NPs.

Ubiquitination of p21 by E3 ligase RNF135 promotes the proliferation of human glioblastoma cells

Glioblastoma multiforme (GBM) is a highly heterogeneous tumor of the central nervous system with a high mortality rate. The upregulation of RING finger protein 135 (RNF135), an E3 ligase, has been observed in GBM, but the associated mechanisms have not been fully elucidated. The aim of the present study was to identify the substrate of RNF135 and study its functions in GBM. Bioinformatics analyses were performed. In addition, RNF135 was overexpressed or knocked down in human U87 and U251 GBM cells, and the effect on cell proliferation was analyzed using Cell Counting Kit-8 and colony formation assays. Furthermore, the interaction of RNF135 with its potential substrate was analyzed using glutathione S-transferase, yeast two-hybrid, immunoprecipitation (IP), co-IP and immunoblotting assays. Bioinformatics analysis indicated that RNF135 serves as a marker of poor prognosis in GBM. The overexpression of RNF135 was demonstrated to promote the proliferation of GBM cells, while the knockdown of RNF135 inhibited GBM cell growth. In addition, the results of the interaction experiments indicate that RNF135 interacts with p21 and mediates the degradation of p21 by ubiquitination. The major site of RNF135-mediated p21 ubiquitination was identified as K163. Further experiments demonstrated that RNF135 promotes the proliferation of GBM cells mainly via p21. In summary, these findings suggest that RNF135 has potential as a therapeutic target for the treatment of GBM.

A novel compound heterozygous mutation of UFC1 in a patient with neurodevelopmental disorder

BACKGROUND

Neurodevelopmental disorders (NDDs) encompass a diverse group of disorders characterized by impaired cognition, behavior, and motor skills. Genetic factor is the leading cause in about 35% of NDDs patients. Mutations of UFC1, an E2 enzyme participating in the post-translational modification of proteins through attachment of ubiquitin-like proteins, were recently reported to be associated with NDDs. However, the UFC1 associated NDDs are rare and the data are scarce, thus making it difficult to identify this disease.

OBJECTIVE

This study reported a novel compound heterozygous mutation of UFC1 in a Chinese patient with NDD.

METHODS

Detailed clinical data were recorded. Whole exome sequencing (WES) was performed to determine the genetic cause of the patient. The candidate mutation was verified using Sanger sequencing.

RESULTS

WES analysis identified a novel compound heterozygous mutation of UFC1 (c.19 C > T, p.Arg7* and c.164G > A, p.Arg55Gln). The nonsense mutation c.19 C > T (p.Arg7*) led to a premature truncation of UFC1 and nonsense-mediated RNA decay. Arg55 is highly conserved among orthologues. Molecular modeling predicted that mutation c.164G > A (p.Arg55Gln) may influence the correct folding of UFC1. These two mutations were evaluated as likely pathogenic based on the ACMG guideline. Moreover, neurodevelopmental delay, microcephaly, and epilepsy were confirmed as major phenotypes of UFC1 mutation.

CONCLUSION

This study expands the mutational spectrum of NDDs. We reported the nonsense mutation of UFC1 for the first time. We also confirmed the major phenotypes that may guide clinical identification of UFC1 mutation. Ubiquitination mechanism is highlighted in NDDs pathogenesis.

Posttranslational modifications of E2F family members in the physiological state and in cancer: Roles, mechanisms and therapeutic targets

The E2F transcription factor family, whose members are encoded by the E2F1-E2F8 genes, plays pivotal roles in the cell cycle, apoptosis, metabolism, stemness, metastasis, aging, angiogenesis, tumor promotion or suppression, and other biological processes. The activity of E2Fs is regulated at multiple levels, with posttranslational modifications being an important regulatory mechanism. There are numerous types of posttranslational modifications, among which phosphorylation, acetylation, methylation, ubiquitination, SUMOylation, neddylation, and poly(ADP-ribosyl)ation are the most commonly studied in the context of the E2F family. Posttranslational modifications of E2F family proteins regulate their biological activity, stability, localization, and interactions with other biomolecules, affecting cell proliferation, apoptosis, DNA damage, etc., and thereby playing roles in physiological and pathological processes. Notably, these modifications do not always act alone but rather form an interactive regulatory network. Currently, several drugs targeting posttranslational modifications are being studied or clinically applied, in which the proteolysis-targeting chimera and molecular glue can target E2Fs. This review aims to summarize the roles and regulatory mechanisms of different PTMs of E2F family members in the physiological state and in cancer and to briefly discuss their clinical significance and potential therapeutic use.

Proteomic analysis reveals a PLK1-dependent G2/M degradation program and a role for AKAP2 in coordinating the mitotic cytoskeleton

Ubiquitination is an essential regulator of cell division. The kinase Polo-like kinase 1 (PLK1) promotes protein degradation at G2/M phase through the E3 ubiquitin ligase Skp1-Cul1-F box (SCF)βTrCP. However, the magnitude to which PLK1 shapes the mitotic proteome is uncharacterized. Combining quantitative proteomics with pharmacologic PLK1 inhibition revealed a widespread, PLK1-dependent program of protein breakdown at G2/M. We validated many PLK1-regulated proteins, including substrates of the cell-cycle E3 SCFCyclin F, demonstrating that PLK1 promotes proteolysis through at least two distinct E3 ligases. We show that the protein-kinase-A-anchoring protein A-kinase anchor protein 2 (AKAP2) is cell-cycle regulated and that its mitotic degradation is dependent on the PLK1/βTrCP signaling axis. Expression of a non-degradable AKAP2 mutant resulted in actin defects and aberrant mitotic spindles, suggesting that AKAP2 degradation coordinates cytoskeletal organization during mitosis. These findings uncover PLK1's far-reaching role in shaping the mitotic proteome post-translationally and have potential implications in malignancies where PLK1 is upregulated.

Inhibitor of Myom3 inhibits proliferation and promotes differentiation of sheep myoblasts

Skeletal muscle quality and yield are important production traits in livestock, and improving skeletal muscle quality while increasing its yield is an important goal of economic breeding. The proliferation and differentiation process of sheep myoblasts directly affects the growth and development of their muscles, thereby affecting the yield of mutton. Myomesin 3 (Myom3), as a functional gene related to muscle growth, currently lacks research on its function in myoblasts. This study aims to investigate the effect of the Myom3 gene on the proliferation and differentiation of sheep myoblasts and its potential molecular mechanisms. The results showed that inhibitor of Myom3 in the proliferation phase of myoblasts resulted in significant downregulation of the proliferation marker gene paired box 7 (Pax7) and myogenic regulatory factors (MRFs; Myf5, Myod1, Myog, P < 0.01), a significant decrease in the EdU-positive cell rate (P < 0.05), and a significant increase in the cell apoptosis rate (P < 0.01), which inhibited the proliferation of myoblasts and promoted their apoptosis. During the differentiation phase of myoblasts, the inhibitor of Myom3 resulted in significant downregulation of the Pax7 gene, upregulation of MRFs (Myod1, Myog, P < 0.05), and a significant increase in fusion index (P < 0.05), promoting the differentiation of myoblasts. Further transcriptome sequencing revealed that differentially expressed genes in the Myom3 interference group were mainly enriched in the MAPK signaling pathway, TNF signaling pathway, and IL-17 signaling pathway. In summary, the inhibitor of Myom3 inhibits myoblast proliferation and promotes myoblast differentiation. Therefore, Myom3 has a potential regulatory effect on the growth and development of sheep muscles, and in-depth functional research can be used for molecular breeding practices in sheep.

A review: targeting UBR5 domains to mediate emerging roles and mechanisms - chance or necessity?

Ubiquitinases are known to catalyze ubiquitin chains on target proteins to regulate various physiological functions like cell proliferation, autophagy, apoptosis, and cell cycle progression. As a member of E3 ligase, ubiquitin protein ligase E3 component n-recognin 5 (UBR5) belongs to the HECT E3 ligase and has been reported to be correlated with various pathophysiological processes. In this review, the authors give a comprehensive insight into the structure and function of UBR5. The authors discuss the specific domains of UBR5 and explore their biological functions separately. Furthermore, the authors describe the involvement of UBR5 in different pathophysiological conditions, including immune response, virus infection, DNA damage response, and protein quality control. Moreover, the authors provide a thorough summary of the important roles and regulatory mechanisms of UBR5 in cancers and other diseases. On the whole, investigating the domains and functions of UBR5, elucidating the underlying mechanisms of UBR5 with various substrates in detail may provide new theoretical basis for the treatment of diseases, including cancers, which could improve future studies to construct novel UBR5-targeted therapy strategies.

CDC7 inhibition impairs neuroendocrine transformation in lung and prostate tumors through MYC degradation

Neuroendocrine (NE) transformation is a mechanism of resistance to targeted therapy in lung and prostate adenocarcinomas leading to poor prognosis. Up to date, even if patients at high risk of transformation can be identified by the occurrence of Tumor Protein P53 (TP53) and Retinoblastoma Transcriptional Corepressor 1 (RB1) mutations in their tumors, no therapeutic strategies are available to prevent or delay histological transformation. Upregulation of the cell cycle kinase Cell Division Cycle 7 (CDC7) occurred in tumors during the initial steps of NE transformation, already after TP53/RB1 co-inactivation, leading to induced sensitivity to the CDC7 inhibitor simurosertib. CDC7 inhibition suppressed NE transdifferentiation and extended response to targeted therapy in in vivo models of NE transformation by inducing the proteasome-mediated degradation of the MYC Proto-Oncogen (MYC), implicated in stemness and histological transformation. Ectopic overexpression of a degradation-resistant MYC isoform reestablished the NE transformation phenotype observed on targeted therapy, even in the presence of simurosertib. CDC7 inhibition also markedly extended response to standard cytotoxics (cisplatin, irinotecan) in lung and prostate small cell carcinoma models. These results nominate CDC7 inhibition as a therapeutic strategy to constrain lineage plasticity, as well as to effectively treat NE tumors de novo or after transformation. As simurosertib clinical efficacy trials are ongoing, this concept could be readily translated for patients at risk of transformation.

Role of MARCH E3 ubiquitin ligases in cancer development

Membrane-associated RING-CH (MARCH) E3 ubiquitin ligases, a family of RING-type E3 ubiquitin ligases, have garnered increased attention for their indispensable roles in immune regulation, inflammation, mitochondrial dynamics, and lipid metabolism. The MARCH E3 ligase family consists of eleven distinct members, and the dysregulation of many of these members has been documented in several human malignancies. Over the past two decades, extensive research has revealed that MARCH E3 ligases play pivotal roles in cancer progression by ubiquitinating key oncogenes and tumor suppressors and orchestrating various signaling pathways. Some MARCH E3s act as oncogenes, while others act as tumor suppressors, and the majority of MARCH E3s play both oncogenic and tumor suppressive roles in a context-dependent manner. Notably, there is special emphasis on the sole mitochondrial MARCH E3 ligase MARCH5, which regulates mitochondrial homeostasis within cancer cells. In this review, we delve into the diverse functions of MARCH E3 ligases across different cancer types, shedding light on the underlying molecular mechanisms mediating their effects, their regulatory effects on cancer and their potential as therapeutic targets.

Unlocking the unfolded structure of ubiquitin: Combining time-resolved x-ray solution scattering and molecular dynamics to generate unfolded ensembles

The unfolding dynamics of ubiquitin were studied using a combination of x-ray solution scattering (XSS) and molecular dynamics (MD) simulations. The kinetic analysis of the XSS ubiquitin signals showed that the protein unfolds through a two-state process, independent of the presence of destabilizing salts. In order to characterize the ensemble of unfolded states in atomic detail, the experimental XSS results were used as a constraint in the MD simulations through the incorporation of x-ray scattering derived potential to drive the folded ubiquitin structure toward sampling unfolded states consistent with the XSS signals. We detail how biased MD simulations provide insight into unfolded states that are otherwise difficult to resolve and underscore how experimental XSS data can be combined with MD to efficiently sample structures away from the native state. Our results indicate that ubiquitin samples unfolded in states with a high degree of loss in secondary structure yet without a collapse to a molten globule or fully solvated extended chain. Finally, we propose how using biased-MD can significantly decrease the computational time and resources required to sample experimentally relevant nonequilibrium states.

The ubiquitin-proteasome system in the regulation of tumor dormancy and recurrence

Tumor recurrence is a mechanism triggered in sparse populations of cancer cells that usually remain in a quiescent state after strict stress and/or therapeutic factors, which is affected by a variety of autocrine and microenvironmental cues. Despite thorough investigations, the biology of dormant and/or cancer stem cells is still not fully elucidated, as for the mechanisms of their reawakening, while only the major molecular patterns driving the relapse process have been identified to date. These molecular patterns profoundly interfere with the elements of cellular proteostasis systems that support the efficiency of the recurrence process. As a major proteostasis machinery, we review the role of the ubiquitin-proteasome system (UPS) in tumor cell dormancy and reawakening, devoting particular attention to the functions of its components, E3 ligases, deubiquitinating enzymes and proteasomes in cancer recurrence. We demonstrate how UPS components functionally or mechanistically interact with the pivotal proteins implicated in the recurrence program and reveal that modulators of the UPS hold promise to become an efficient adjuvant therapy for eradicating refractory tumor cells to impede tumor relapse.

Functional characterization of Cullin-1-RING ubiquitin ligase (CRL1) complex in Leishmania infantum

Cullin-1-RING ubiquitin ligases (CRL1) or SCF1 (SKP1-CUL1-RBX1) E3 ubiquitin ligases are the largest and most extensively investigated class of E3 ligases in mammals that regulate fundamental processes, such as the cell cycle and proliferation. These enzymes are multiprotein complexes comprising SKP1, CUL1, RBX1, and an F-box protein that acts as a specificity factor by interacting with SKP1 through its F-box domain and recruiting substrates via other domains. E3 ligases are important players in the ubiquitination process, recognizing and transferring ubiquitin to substrates destined for degradation by proteasomes or processing by deubiquitinating enzymes. The ubiquitin-proteasome system (UPS) is the main regulator of intracellular proteolysis in eukaryotes and is required for parasites to alternate hosts in their life cycles, resulting in successful parasitism. Leishmania UPS is poorly investigated, and CRL1 in L. infantum, the causative agent of visceral leishmaniasis in Latin America, is yet to be described. Here, we show that the L. infantum genes LINF_110018100 (SKP1-like protein), LINF_240029100 (cullin-like protein-like protein), and LINF_210005300 (ring-box protein 1 -putative) form a LinfCRL1 complex structurally similar to the H. sapiens CRL1. Mass spectrometry analysis of the LinfSkp1 and LinfCul1 interactomes revealed proteins involved in several intracellular processes, including six F-box proteins known as F-box-like proteins (Flp) (data are available via ProteomeXchange with identifier PXD051961). The interaction of LinfFlp 1-6 with LinfSkp1 was confirmed, and using in vitro ubiquitination assays, we demonstrated the function of the LinfCRL1(Flp1) complex to transfer ubiquitin. We also found that LinfSKP1 and LinfRBX1 knockouts resulted in nonviable L. infantum lineages, whereas LinfCUL1 was involved in parasite growth and rosette formation. Finally, our results suggest that LinfCul1 regulates the S phase progression and possibly the transition between the late S to G2 phase in L. infantum. Thus, a new class of E3 ubiquitin ligases has been described in L. infantum with functions related to various parasitic processes that may serve as prospective targets for leishmaniasis treatment.

Prognostic value and drug sensitivity of F‑box and leucine‑rich repeat protein 6 in glioma

Gliomas are highly malignant and invasive tumors lacking clear boundaries. Previous bioinformatics and experimental analyses have indicated that F-box and leucine-rich repeat protein 6 (FBXL6), a protein crucial for the cell cycle and tumorigenesis, is highly expressed in certain types of tumors. The high expression level of FBXL6 is reported to promote tumor growth and adversely affect patient survival. However, the molecular mechanism, prognostic value and drug sensitivity of FBXL6 in glioma remain unclear. To address this, the present study analyzed FBXL6 expression in gliomas, utilizing data from The Cancer Genome Atlas and Chinese Glioma Genome Atlas databases. Analysis of FBXL6 mRNA expression levels, combined with patient factors such as age, sex and tumor grade using Kaplan-Meier plots and nomograms, demonstrated a strong correlation between FBXL6 expression and glioma progression. Co-expression networks provided further insights into the biological function of FBXL6. Additionally, using CIBERSORT and TISDB tools, the correlation between FBXL6 expression correlation tumor-infiltrating immune cells and immune genes was demonstrated to be statistically significant. These findings were validated by examining FBXL6 mRNA and protein levels in glioma tissues using various techniques, including western blot, reverse transcription-quantitative PCR and immunohistochemistry. These assays demonstrated the role of FBXL6 in glioma progression. Furthermore, drug sensitivity analysis demonstrated a strong correlation between FBXL6 expression and various drugs, which indicated that FBXL6 may potentially act as a future promising therapeutic target in glioma treatment. Therefore, the present study identified FBXL6 as a diagnostic and prognostic marker in patients with gliomas and highlighted its potential role in glioma progression.

Advances of E3 ligases in lung cancer

Lung cancer is a leading cause of cancer-related death, and the most common type of lung cancer is non-small cell lung cancer, which accounts for approximately 85 % of lung cancer diagnoses. Recent studies have revealed that ubiquitination acts as a crucial part of the development and progression of lung cancer. The E1-E2-E3 three-enzyme cascade has a core function in ubiquitination, so targeted adjustments of E3 ligases could be used in lung cancer treatment. Hence, we elucidate research advances in lung cancer-related E3 ligases by briefly describing the structure and categorization of E3 ligases. Here, we provide a detailed review of the mechanisms by which lung cancer-related E3 ligases modify substrate proteins and regulate signaling pathways to facilitate or suppress cancer progression. We hope to show a new perspective on targeted precision therapy for lung cancer.

Ectoine enhances recombinant antibody production in Chinese hamster ovary cells by promoting cell cycle arrest

Chinese hamster ovary (CHO) cells represent the most preferential host cell system for therapeutic monoclonal antibody (mAb) production. Enhancing mAb production in CHO cells can be achieved by adding chemical compounds that regulate the cell cycle and cell survival pathways. This study investigated the impact of ectoine supplementation on mAb production in CHO cells. The results showed that adding ectoine at a concentration of 100 mM on the 3rd day of cultivation improved mAb production by improving cell viability and extending the culture duration. RNA sequencing analysis revealed differentially expressed genes associated with cell cycle regulation, cell proliferation, and cellular homeostasis, in particular promotion of cell cycle arrest, which was then confirmed by flow cytometry analysis. Ectoine-treated CHO cells exhibited an increase in the number of cells in the G0/G1 phase. In addition, the cell diameter was also increased. These findings support the hypothesis that ectoine enhances mAb production in CHO cells through mechanisms involving cell cycle arrest and cellular homeostasis. Overall, this study highlights the potential of ectoine as a promising supplementation strategy to enhance mAb production not only in CHO cells but also in other cell lines.

Identification of biomarkers related to angiogenesis in myocardial ischemia-reperfusion injury and prediction of potential drugs

Myocardial ischemia-reperfusion injury (MIRI) refers to the secondary damage to myocardial tissue that occurs when blood perfusion is rapidly restored following myocardial ischemia. This process often exacerbates the injury to myocardial fiber structure and function. The activation mechanism of angiogenesis is closely related to MIRI and plays a significant role in the occurrence and progression of ischemic injury. In this study, we utilized sequencing data from the GEO database and employed WGCNA, Mfuzz cluster analysis, and protein interaction network to identify Stat3, Rela, and Ubb as hub genes involved in MIRI-angiogenesis. Additionally, the GO and KEGG analysis of differentially expressed genes highlighted their broad participation in inflammatory responses and associated signaling pathways. Moreover, the analysis of sequencing data and hub genes revealed a notable increase in the infiltration ratio of monocytes and activated mast cells. By establishing key cell ROC curves, using independent datasets, and validating the expression of hub genes, we demonstrated their high diagnostic value. Moreover, by scrutinizing single-cell sequencing data alongside trajectory analysis, it has come to light that Stat3 and Rela exhibit predominant expression within Dendritic cells. In contrast, Ubb demonstrates expression across multiple cell types, with all three genes being expressed at distinct stages of cellular development. Lastly, leveraging the CMap database, we predicted potential small molecule compounds for the identified hub genes and validated their binding activity through molecular docking. Ultimately, our research provides valuable evidence and references for the early diagnosis and treatment of MIRI from the perspective of angiogenesis.

Studies on Human Cultured Fibroblasts and Cutaneous Squamous Cell Carcinomas Suggest That Overexpression of Histone Variant H2A.J Promotes Radioresistance and Oncogenic Transformation

Background: Cellular senescence in response to ionizing radiation (IR) limits the replication of damaged cells by causing permanent cell cycle arrest. However, IR can induce pro-survival signaling pathways that reduce the extent of radiation-induced cytotoxicity and promote the development of radioresistance. The differential incorporation of histone variant H2A.J has profound effects on higher-order chromatin organization and on establishing the epigenetic state of radiation-induced senescence. However, the precise epigenetic mechanism and function of H2A.J overexpression in response to IR exposure still needs to be elucidated. Methods: Primary (no target, NT) and genetically modified fibroblasts overexpressing H2A.J (H2A.J-OE) were exposed to 20 Gy and analyzed 2 weeks post-IR for radiation-induced senescence by immunohistochemistry and immunofluorescence microscopy. Transcriptome signatures were analyzed in (non-)irradiated NT and H2A.J-OE fibroblasts by RNA sequencing. Since H2A.J plays an important role in the epidermal homeostasis of human skin, the oncogenic potential of H2A.J was investigated in cutaneous squamous cell carcinoma (cSCC). The tissue microarrays of cSCC were analyzed for H2A.J protein expression pattern by automated image analysis. Results: In response to radiation-induced DNA damage, the overexpression of H2A.J impairs the formation of senescence-associated heterochromatin foci (SAHF), thereby inhibiting the SAHF-mediated silencing of proliferation-promoting genes. The dysregulated activation of cyclins and cyclin-dependent kinases disturbs cell cycle arrest in irradiated H2A.J-OE fibroblasts, thereby overcoming radiation-induced senescence. Comparative transcriptome analysis revealed significantly increased WNT16 signaling in H2A.J OE fibroblasts after IR exposure, promoting the fundamental mechanisms of tumor development and progression, including the activation of the epithelial-mesenchymal transition. The quantitative analysis of cSCCs revealed that undifferentiated tumors are associated with high nuclear H2A.J expression, related with greater oncogenic potential. Conclusion: H2A.J overexpression induces radioresistance and promotes oncogenic transformation through the activation of WNT16 signaling pathway functions. H2A.J-associated signatures may improve risk stratification by identifying patients with more aggressive cSCC who may require radiotherapy with increased doses.

LncRNA AFAP1-AS1 Promotes Oral Squamous Cell Carcinoma Development by Ubiquitin-Mediated Proteolysis

BACKGROUND AND PURPOSE

Long noncoding RNA (lncRNA) dysregulation has been reported to play a pivotal role in the development of cancers. In this study, we aimed to screen the key lncRNA in oral squamous cell carcinoma (OSCC) via bioinformatics analysis and further validate the function of lncRNA in vitro and in vivo.

METHODS

Bioinformatics analysis was conducted to identify differentially expressed lncRNAs between control and OSCC samples. Quantitative real-time-polymerase chain reaction was employed to detect the expression of differentially expressed lncRNAs in human tongue squamous cell carcinoma and human oral keratinocytes cell lines. The biological function of lncRNA and its mechanism were examined via the experimental assessment of the cell lines with the lncRNA overexpressed and silenced. Additionally, to further explore the function of lncRNA in the progression of OSCC, xenograft tumour mouse models were established using 25 mice (5 groups, each with 5 mice). Tumour formation was observed at 2 weeks after the cell injection, and the tumours were resected at 5 weeks post-implantation.

RESULTS

Two lncRNAs, LINC00958 and AFAP1-AS1, were found to be correlated with the prognosis of OSCC. The results of the quantitative real-time-polymerase chain reaction indicated that the 2 lncRNAs were highly expressed in OSCC. In combination with the previous literature, we found AFAP1-AS1 to be a potentially important biomarker for OSCC. Thus, we further investigated its biological function and found that AFAP1-AS1 silencing inhibited cell proliferation, migration, and invasion whereas AFAP1-AS1 overexpression reversed the effect of AFAP1-AS1 silencing (P < .05). Mechanism analysis revealed that AFAP1-AS1 regulated the development of OSCC through the ubiquitin-mediated proteolysis pathway.

CONCLUSIONS

AFAP1-AS1 is an oncogene that aggravates the development of OSCC via the ubiquitin-mediated proteolysis pathway. It also provides a novel potential therapy for OSCC.

The crosstalk between non-coding RNAs and cell-cycle events: A new frontier in cancer therapy

The cell cycle comprises sequential events during which a cell duplicates its genome and divides it into two daughter cells. This process is tightly regulated to ensure that the daughter cell receives identical copied chromosomal DNA and that any errors in the DNA during replication are correctly repaired. Cyclins and their enzyme partners, cyclin-dependent kinases (CDKs), are critical regulators of G- to M-phase transitions during the cell cycle. Mitogenic signals induce the formation of the cyclin/CDK complexes, resulting in phosphorylation and activation of the CDKs. Once activated, cyclin/CDK complexes phosphorylate specific substrates that drive the cell cycle forward. The sequential activation and inactivation of cyclin-CDK complexes are tightly controlled by activating and inactivating phosphorylation events induced by cell-cycle proteins. The non-coding RNAs (ncRNAs), which do not code for proteins, regulate cell-cycle proteins at the transcriptional and translational levels, thereby controlling their expression at different cell-cycle phases. Deregulation of ncRNAs can cause abnormal expression patterns of cell-cycle-regulating proteins, resulting in abnormalities in cell-cycle regulation and cancer development. This review explores how ncRNA dysregulation can disrupt cell division balance and discusses potential therapeutic approaches targeting these ncRNAs to control cell-cycle events in cancer treatment.

Cell cycle machinery in oncology: A comprehensive review of therapeutic targets

The cell cycle is tightly regulated to ensure controlled cell proliferation. Dysregulation of the cell cycle machinery is a hallmark of cancer that leads to unchecked growth. This review comprehensively analyzes key molecular regulators of the cell cycle and how they contribute to carcinogenesis when mutated or overexpressed. It focuses on cyclins, cyclin-dependent kinases (CDKs), CDK inhibitors, checkpoint kinases, and mitotic regulators as therapeutic targets. Promising strategies include CDK4/6 inhibitors like palbociclib, ribociclib, and abemaciclib for breast cancer treatment. Other possible targets include the anaphase-promoting complex/cyclosome (APC/C), Skp2, p21, and aurora kinase inhibitors. However, challenges with resistance have limited clinical successes so far. Future efforts should focus on combinatorial therapies, next-generation inhibitors, and biomarkers for patient selection. Targeting the cell cycle holds promise but further optimization is necessary to fully exploit it as an anti-cancer strategy across diverse malignancies.

UCHL1 promotes the proliferation of porcine granulosa cells by stabilizing CCNB1

BACKGROUND

The proliferation of porcine ovarian granulosa cells (GCs) is essential to follicular development and the ubiquitin-proteasome system is necessary for maintaining cell cycle homeostasis. Previous studies found that the deubiquitinase ubiquitin carboxyl-terminal hydrolase 1 (UCHL1) regulates female reproduction, especially in ovarian development. However, the mechanism by which UCHL1 regulates porcine GC proliferation remains unclear.

RESULTS

UCHL1 overexpression promoted GC proliferation, and knockdown had the opposite effect. UCHL1 is directly bound to cyclin B1 (CCNB1), prolonging the half-life of CCNB1 and inhibiting its degradation, thereby promoting GC proliferation. What's more, a flavonoid compound-isovitexin improved the enzyme activity of UCHL1 and promoted the proliferation of porcine GCs.

CONCLUSIONS

UCHL1 promoted the proliferation of porcine GCs by stabilizing CCNB1, and isovitexin enhanced the enzyme activity of UCHL1. These findings reveal the role of UCHL1 and the potential of isovitexin in regulating proliferation and provide insights into identifying molecular markers and nutrients that affect follicle development.

The Nucleolar Protein C1orf131 Is a Novel Gene Involved in the Progression of Lung Adenocarcinoma Cells through the AKT Signalling Pathway

Lung adenocarcinoma (LUAD) is the most widespread cancer in the world, and its development is associated with complex biological mechanisms that are poorly understood. Here, we revealed a marked upregulation in the mRNA level of C1orf131 in LUAD samples compared to non-tumor tissue samples in The Cancer Genome Atlas (TCGA). Depletion of C1orf131 suppressed cell proliferation and growth, whereas it stimulated apoptosis in LUAD cells. Mechanistic investigations revealed that C1orf131 knockdown induced cell cycle dysregulation via the AKT and p53/p21 signalling pathways. Additionally, C1orf131 knockdown blocked cell migration through the modulation of epithelial-mesenchymal transition (EMT) in lung adenocarcinoma. Notably, we identified the C1orf131 protein nucleolar localization sequence, which included amino acid residues 137-142 (KKRKLT) and 240-245 (KKKRKG). Collectively, C1orf131 has potential as a novel therapeutic marker for patients in the future, as it plays a vital role in the progression of lung adenocarcinoma.

Tracking Inhibition of Human Small C-Terminal Domain Phosphatase 1 Using 193 nm Ultraviolet Photodissociation Mass Spectrometry

Working in tandem with kinases via a dynamic interplay of phosphorylation and dephosphorylation of proteins, phosphatases regulate many cellular processes and thus represent compelling therapeutic targets. Here we leverage ultraviolet photodissociation to shed light on the binding characteristics of two covalent phosphatase inhibitors, T65 and rabeprazole, and their respective interactions with the human small C-terminal domain phosphatase 1 (SCP1) and its single-point mutant C181A, in which a nonreactive alanine replaces one key reactive cysteine. Top-down MS/MS analysis is used to localize the binding of T65 and rabeprazole on the two proteins and estimate the relative reactivities of each cysteine residue.

Effect of static magnetic field on gene expression of human umbilical cord mesenchymal stem cells by transcriptome analysis

PURPOSE

Static magnetic fields (SMFs) induce various biological reactions and have been applied in the biological therapy of diseases, especially in combination with mesenchymal stem cells (MSCs) and tissue engineering. However, the underlying influence of SMFs on MSCs gene expression remains largely unclear. In this study, we aim to investigate the effects of SMFs on gene expression of human MSCs.

MATERIALS AND METHODS

We exposed human MSCs to two different intensities (0.35 ​T and 1.0 ​T) of SMFs and observed the effects of SMFs on cell morphology. Subsequently, RNA-sequencing was performed to explore the gene expression changes.

RESULTS

Compared with control group cells, no significant differences in cell morphology were observed under a phase contrast inverted microscope, but the transcriptome of SMF-exposed MSCs were significantly changed in both 0.35 ​T and 1.0 ​T groups and the differential expressed genes are involved in multiple pathways, such as ubiquitin mediated proteolysis, TNF signaling pathway, NF-kappa B signaling pathway, TGF-beta signaling pathway, metabolic pathways, and apoptosis, which regulate the biological functions of MSCs.

CONCLUSIONS

SMFs stimulation could affect the gene expression of human MSCs and the biological effects vary by the different intensities of SMFs. These data offer the molecular foundation for future application of SMFs in stem cell technology as well as tissue engineering medicine.

CYR61 Acts as an Intracellular Microtubule-Associated Protein and Coordinates Mitotic Progression via PLK1-FBW7 Pathway

Cysteine-rich angiogenic inducer 61 (CYR61), also called CCN1, has long been characterized as a secretory protein. Nevertheless, the intracellular function of CYR61 remains unclear. Here, we found that CYR61 is important for proper cell cycle progression. Specifically, CYR61 interacts with microtubules and promotes microtubule polymerization to ensure mitotic entry. Moreover, CYR61 interacts with PLK1 and accumulates during the mitotic process, followed by degradation as mitosis concludes. The proteolysis of CYR61 requires the PLK1 kinase activity, which directly phosphorylates two conserved motifs on CYR61, enhancing its interaction with the SCF E3 complex subunit FBW7 and mediating its degradation by the proteasome. Mutations of phosphorylation sites of Ser167 and Ser188 greatly increase CYR61's stability, while deletion of CYR61 extends prophase and metaphase and delays anaphase onset. In summary, our findings highlight the precise control of the intracellular CYR61 by the PLK1-FBW7 pathway, accentuating its significance as a microtubule-associated protein during mitotic progression.

OSBPL2 compound heterozygous variants cause dyschromatosis, ichthyosis, deafness and atopic disease syndrome

PURPOSE

In this study, we identified and diagnosed a novel inherited condition called Dyschromatosis, Ichthyosis, Deafness, and Atopic Disease (DIDA) syndrome. We present a series of studies to clarify the pathogenic variants and specific mechanism.

METHODS

Exome sequencing and Sanger sequencing was conducted in affected and unaffected family members. A variety of human and cell studies were performed to explore the pathogenic process of keratosis.

RESULTS

Our finding indicated that DIDA syndrome was caused by compound heterozygous variants in the oxysterol-binding protein-related protein 2 (OSBPL2) gene. Furthermore, our findings revealed a direct interaction between OSBPL2 and Phosphoinositide phospholipase C-beta-3 (PLCB3), a key player in hyperkeratosis. OSBPL2 effectively inhibits the ubiquitylation of PLCB3, thereby stabilizing PLCB3. Conversely, OSBPL2 variants lead to enhanced ubiquitination and subsequent degradation of PLCB3, leading to epidermal hyperkeratosis, characterized by aberrant proliferation and delayed terminal differentiation of keratinocytes.

CONCLUSIONS

Our study not only unveiled the association between OSBPL2 variants and the newly identified DIDA syndrome but also shed light on the underlying mechanism.

FBXO43 promotes cell cycle progression in cancer cells through stabilizing SKP2

FBXO43 is a member of the FBXO subfamily of F-box proteins, known to be a regulatory hub during meiosis. A body of data showed that FBXO43 is overexpressed in a number of human cancers. However, whether and how FBXO43 affects cell cycle progression and growth of cancer cells remain elusive. In this study, we provide first piece of evidence, showing a pivotal role of FBXO43 in cell cycle progression and growth of cancer cells. Specifically, FBXO43 acts as a positive cell cycle regulator with an oncogenic activity in variety types of human cancer, including non-small cell lung cancer, hepatocellular carcinoma and sarcoma. Mechanistically, FBXO43 interacts with phosphorylated SKP2 induced by AKT1, leading to reduced SKP2 auto-ubiquitylation and subsequent proteasome degradation. Taken together, our study demonstrates that FBXO43 promotes cell cycle progression by stabilizing SKP2, and FBXO43 could serve as a potential anti-cancer target.

A ubiquitin-proteasome system-related signature to predict prognosis, immune infiltration, and therapy efficacy for breast cancer

The ubiquitin-proteasome system (UPS) is an essential regulatory system for maintaining homeostasis, and its dysfunction may cause various diseases. The activity of proteasome and ubiquitin-conjugating enzymes has been found to be greatly increased in breast cancer (BC), indicating that the heterogeneity of UPS may be related to the progression of BC. Gene data was obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases and performed in multiple algorithms to construct a UPS-related signature for BC. Patients in the UPS low-risk group had greater overall and recurrence-free survival probability than those in the UPS high-risk group. This signature was closely associated with functional enrichment. Some high metabolism-related pathways were more active in the UPS high-risk group. The UPS low-risk group had more abundant anti-tumor immune cells, while in the UPS high-risk group, immunosuppressive cells were dominant. More importantly, we found that the UPS low-risk group was more sensitive to immunotherapy, while the UPS high-risk group responded better to radiotherapy. Drug sensitivity analysis identified more effective chemotherapy drugs in different UPS-related risk groups. This UPS-related signature may serve as a novel biomarker and independent prognostic factor for BC. It can effectively predict prognosis, immune infiltration, and therapy efficacy, providing new strategies for individualized treatment.

BHLHE41 inhibits bladder cancer progression via regulation of PYCR1 stability and thus inactivating PI3K/AKT signaling pathway

BACKGROUND

The basic helix-loop-helix family member e41 (BHLHE41) is frequently dysregulated in tumors and plays a crucial role in malignant progression of various cancers. Nevertheless, its specific function and underlying mechanism in bladder cancer (BCa) remain largely unexplored.

METHODS

The expression levels of BHLHE41 in BCa tissues and cells were examined by qRT-PCR and western blot assays. BCa cells stably knocking down or overexpressing BHLHE41 were constructed through lentivirus infection. The changes of cell proliferation, cell cycle distribution, migration, and invasion were detected by CCK-8, flow cytometry, wound healing, transwell invasion assays, respectively. The expression levels of related proteins were detected by western blot assay. The interaction between BHLHE41 and PYCR1 was explored by co-immunoprecipitation analysis.

RESULTS

In this study, we found that BHLHE41 was lowly expressed in bladder cancer tissues and cell lines, and lower expression of BHLHE41 was associated with poor overall survival in bladder cancer patients. Functionally, by manipulating the expression of BHLHE41, we demonstrated that overexpression of BHLHE41 significantly retarded cell proliferation, migration, invasion, and induced cell cycle arrest in bladder cancer through various in vitro and in vivo experiments, while silence of BHLHE41 caused the opposite effect. Mechanistically, we showed that BHLHE41 directly interacted with PYCR1, decreased its stability and resulted in the ubiquitination and degradation of PYCR1, thus inactivating PI3K/AKT signaling pathway. Rescue experiments showed that the effects induced by BHLHE41 overexpression could be attenuated by further upregulating PYCR1.

CONCLUSION

BHLHE41 might be a useful prognostic biomarker and a tumor suppressor in bladder cancer. The BHLHE41/PYCR1/PI3K/AKT axis might be a potential therapeutic target for bladder cancer intervention.

Targeting SOX13 inhibits assembly of respiratory chain supercomplexes to overcome ferroptosis resistance in gastric cancer

Therapeutic resistance represents a bottleneck to treatment in advanced gastric cancer (GC). Ferroptosis is an iron-dependent form of non-apoptotic cell death and is associated with anti-cancer therapeutic efficacy. Further investigations are required to clarify the underlying mechanisms. Ferroptosis-resistant GC cell lines are constructed. Dysregulated mRNAs between ferroptosis-resistant and parental cell lines are identified. The expression of SOX13/SCAF1 is manipulated in GC cell lines where relevant biological and molecular analyses are performed. Molecular docking and computational screening are performed to screen potential inhibitors of SOX13. We show that SOX13 boosts protein remodeling of electron transport chain (ETC) complexes by directly transactivating SCAF1. This leads to increased supercomplexes (SCs) assembly, mitochondrial respiration, mitochondrial energetics and chemo- and immune-resistance. Zanamivir, reverts the ferroptosis-resistant phenotype via directly targeting SOX13 and promoting TRIM25-mediated ubiquitination and degradation of SOX13. Here we show, SOX13/SCAF1 are important in ferroptosis-resistance, and targeting SOX13 with zanamivir has therapeutic potential.

SETD7 Promotes Cell Proliferation and Migration via Methylation-mediated TAF7 in Clear Cell Renal Cell Carcinoma

SET domain containing 7(SETD7), a member of histone methyltransferases, is abnormally expressed in multiple tumor types. However, the biological function and underlying molecular mechanism of SETD7 in clear cell renal cell carcinoma (ccRCC) remain unclear. Here, we explored the biological effects of SETD7-TAF7-CCNA2 axis on proliferation and metastasis in ccRCC. We identified both SETD7 and TAF7 were up-regulated and significantly promoted the proliferation and migration of ccRCC cells. Concurrently, there was a significant positive correlation between the expression of SETD7 and TAF7, and the two were colocalized in the nucleus. Mechanistically, SETD7 methylates TAF7 at K5 and K300 sites, resulting in the deubiquitination and stabilization of TAF7. Furthermore, re-expression of TAF7 could partially restore SETD7 knockdown inhibited ccRCC cells proliferation and migration. In addition, TAF7 transcriptionally activated to drive the expression of cyclin A2 (CCNA2). And more importantly, the methylation of TAF7 at K5 and K300 sites exhibited higher transcriptional activity of CCNA2, which promotes formation and progression of ccRCC. Our findings reveal a unique mechanism that SETD7 mediated TAF7 methylation in regulating transcriptional activation of CCNA2 in ccRCC progression and provide a basis for developing effective therapeutic strategies by targeting members of SETD7-TAF7-CCNA2 axis.

FBXL18 is required for ovarian cancer cell proliferation and migration through activating AKT signaling

BACKGROUND

F-box and leucine-rich repeat protein 18 (FBXL18) is an F-box protein that functions as an E3-ubiquitin ligase, and it plays pivotal roles in multiple disease processes. However, its role and underlying mechanism in ovarian cancer (OC) are still unknown. We investigated the impact and mechanism of FBXL18 in OC cell growth and tumorigenesis.

METHODS

Silent interfering RNAs and overexpression plasmids were employed to knock down and overexpress FBXL18 in OC cells (A2780 and OVCAR3). CCK-8, colony formation, cell migration, and nude mouse xenograft assays were used to assess the effect of FBXL18 on OC cell proliferation and migration. Western blotting and co-immunoprecipitation followed by ubiquitination assays were performed to detect the mechanism of the FBXL18/AKT axis in OC.

RESULTS

FBXL18 knockdown inhibited OC cell proliferation and migration, whereas FBXL18 overexpression showed the opposite results. Phosphorylated-AKT (S473) protein expression was increased by FBXL18 overexpression and markedly decreased after phosphorylated-AKT inhibitor (MK-2206) treatment. Co-immunoprecipitation assays demonstrated that FBXL18 strongly interacted with AKT in OC cells. Ubiquitination assays revealed that FBXL18 promoted K63-linked AKT ubiquitination to activate AKT. MK-2206 treatment reversed the increase in proliferation and migration of OC cells induced by FBXL18 overexpression.

CONCLUSIONS

FBXL18 promoted OC cell proliferation and migration and facilitated OC tumorigenesis. Mechanically, FBXL18 interacted with AKT and promoted K63-linked ubiquitination of AKT to activate AKT in OC cells. Our study revealed that the FBXL18/AKT axis plays a crucial role in the OC process, indicating that FBXL18 may be a valuable target for OC diagnosis and treatment.

Multi-omics integration highlights the role of ubiquitination in endometriosis fibrosis

BACKGROUND

Endometriosis, characterized by the presence of active endometrial-like tissues outside the uterus, causes symptoms like dysmenorrhea and infertility due to the fibrosis of endometrial cells, which involves excessive deposition of extracellular matrix (ECM) proteins. Ubiquitination, an important post-transcriptional modification, regulates various biological processes in human diseases. However, its role in the fibrosis process in endometriosis remains unclear.

METHODS

We employed multi-omics approaches on two cohorts of endometriosis patients with 39 samples. GO terms and KEGG pathways enrichment analyses were used to investigate the functional changes involved in endometriosis. Pearson's correlation coefficient analysis was conducted to explore the relationship between global proteome and ubiquitylome in endometriosis. The protein expression levels of ubiquitin-, fibrosis-related proteins, and E3 ubiquitin-protein ligase TRIM33 were validated via Western blot. Transfecting human endometrial stroma cells (hESCs) with TRIM33 small interfering RNA (siRNA) in vitro to explore how TRIM33 affects fibrosis-related proteins.

RESULTS

Integration of proteomics and transcriptomics showed genes with concurrent change of both mRNA and protein level which involved in ECM production in ectopic endometria. Ubiquitylomics distinguished 1647 and 1698 ubiquitinated lysine sites in the ectopic (EC) group compared to the normal (NC) and eutopic (EU) groups, respectively. Further multi-omics integration highlighted the essential role of ubiquitination in key fibrosis regulators in endometriosis. Correlation analysis between proteome and ubiquitylome showed correlation coefficients of 0.32 and 0.36 for ubiquitinated fibrosis proteins in EC/NC and EC/EU groups, respectively, indicating positive regulation of fibrosis-related protein expression by ubiquitination in ectopic lesions. We identified ubiquitination in 41 pivotal proteins within the fibrosis-related pathway of endometriosis. Finally, the elevated expression of TGFBR1/α-SMA/FAP/FN1/Collagen1 proteins in EC tissues were validated across independent samples. More importantly, we demonstrated that both the mRNA and protein levels of TRIM33 were reduced in endometriotic tissues. Knockdown of TRIM33 promoted TGFBR1/p-SMAD2/α-SMA/FN1 protein expressions in hESCs but did not significantly affect Collagen1/FAP levels, suggesting its inhibitory effect on fibrosis in vitro.

CONCLUSIONS

This study, employing multi-omics approaches, provides novel insights into endometriosis ubiquitination profiles and reveals aberrant expression of the E3 ubiquitin ligase TRIM33 in endometriotic tissues, emphasizing their critical involvement in fibrosis pathogenesis and potential therapeutic targets.

Overexpression of GPX2 gene regulates the development of porcine preadipocytes and skeletal muscle cells through MAPK signaling pathway

Glutathione peroxidase 2 (GPX2) is a selenium-dependent enzyme and protects cells against oxidative damage. Recently, GPX2 has been identified as a candidate gene for backfat and feed efficiency in pigs. However, it is unclear whether GPX2 regulates the development of porcine preadipocytes and skeletal muscle cells. In this study, adenoviral gene transfer was used to overexpress GPX2. Our findings suggest that overexpression of GPX2 gene inhibited proliferation of porcine preadipocytes. And the process is accompanied by the reduction of the p-p38. GPX2 inhibited adipogenic differentiation and promoted lipid degradation, while ERK1/2 was reduced and p-p38 was increased. Proliferation of porcine skeletal muscle cells was induced after GPX2 overexpression, was accompanied by activation in JNK, ERK1/2, and p-p38. Overexpression methods confirmed that GPX2 has a promoting function in myoblastic differentiation. ERK1/2 pathway was activated and p38 was suppressed during the process. This study lays a foundation for the functional study of GPX2 and provides theoretical support for promoting subcutaneous fat reduction and muscle growth.

A comprehensive review of phytoconstituents in liver cancer prevention and treatment: targeting insights into molecular signaling pathways

Primary liver cancer is a type of cancer that develops in the liver. Hepatocellular carcinoma is a primary liver cancer that usually affects adults. Liver cancer is a fatal global condition that affects millions of people worldwide. Despite advances in technology, the mortality rate remains alarming. There is growing interest in researching alternative medicines to prevent or reduce the effects of liver cancer. Recent studies have shown growing interest in herbal products, nutraceuticals, and Chinese medicines as potential treatments for liver cancer. These substances contain unique bioactive compounds with anticancer properties. The causes of liver cancer and potential treatments are discussed in this review. This study reviews natural compounds, such as curcumin, resveratrol, green tea catechins, grape seed extracts, vitamin D, and selenium. Preclinical and clinical studies have shown that these medications reduce the risk of liver cancer through their antiviral, anti-inflammatory, antioxidant, anti-angiogenic, and antimetastatic properties. This article discusses the therapeutic properties of natural products, nutraceuticals, and Chinese compounds for the prevention and treatment of liver cancer.

PDLIM7 Promotes Tumor Metastasis in Papillary Thyroid Carcinoma via Stabilizing Focal Adhesion Kinase Protein

Background: As an actin cytoskeleton interactor, PDZ (postsynaptic density 65-discs large-zonula occludens 1) and LIM (abnormal cell lineage 11-isket 1-mechanosensory abnormal 3) domain protein 7 (PDLIM7) was supposed to play an essential role modulating cytoskeleton. Focal adhesions (FAs), which are located at the cytomembrane terminus of actin cytoskeleton, function as a force sensor and can transform the mechanical signal to a biochemical signal. Focal adhesion kinase (FAK) localizes to and regulates signal transduction in FAs, which play an essential role in cell polarity, migration, and invasion. However, whether PDLIM7 is involved in FAs-associated signal transduction and its role in tumor invasion and metastasis remains largely unknown. Methods: A cohort of 80 patients with papillary thyroid carcinoma (PTC) at The Second Affiliated Hospital of Guilin Medical University, as well as 512 PTC samples from The Cancer Genome Atlas thyroid cancer database was utilized to analyze the expression of PDLIM7 and its association with prognosis. Survival data were assessed using Kaplan-Meier curves, whereas clinicopathological characteristics such as age, sex, tumor size, multilocality, extrathyroidal extension, lymph metastases, Hashimoto's thyroiditis, distant metastasis, and TNM stage were considered. Functional assays were performed in vitro and in a xenograft mouse model to assess the role of PDLIM7 in PTC cell lines. The colocalization of PDLIM7 with FAK and integrin alpha V (ITGAV) was determined using immunofluorescence assay and immunoprecipitation assay. Protein expression levels in cell and tissue biopsies were measured through Western blotting and immunohistochemistry. Results: (1) The PDLIM7 protein frequently upregulated in both PTC tissues and cells, and overexpression of PDLIM7 is associated with advanced clinicopathological characteristics. (2) Knockdown of PDLIM7 effectively inhibits cell proliferation, migration, and invasion in PTC cell lines in vitro. (3) Knockdown of PDLIM7 hinders the growth and metastasis of TPC-1 xenografts in vivo. (4) PDLIM7 demonstrates colocalization with both FAK and the FA molecule ITGAV and the knockdown of PDLIM7 resulted in disassembly of FAs and proteosome-dependent degradation of FAK in PTC cell lines. Conclusions: PDLIM7 function as an oncoprotein in PTC to promote metastasis, and a novel underlying mechanism is proposed that PDLIM7 keeps FAK protein from proteosome-dependent degradation.

Anticancer potential of grifolin in lung cancer treatment through PI3K/AKT pathway inhibition

Objective

Grifolin is a natural secondary metabolite isolated from edible fruiting bodies of the mushroom Albatrellus confluens. Grifolin has antitumor activities in several types of cancer. We aimed to determine the effects of grifolin on lung cancer.

Methods

We determined the proliferation, migration, invasion, and apoptosis of lung cancer cells using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Ethynyl deoxyuridine, colony formation, wound scratch, transwell, flow cytometry, and xenograft mouse assays. Molecular docking evaluated the binding relation between grifolin and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA). The levels of PIK3CA, AKT, and p-AKT were measured by western blot.

Results

Grifolin (10, 20, or 40 μM) inhibited the proliferation, migration, and invasion of lung cancer cells, and induced cell cycle arrest and apoptosis. Grifolin also decreased CDK4, CDK6, and CyclinD1 expression and significantly decreased PIK3CA and p-AKT expression in lung cancer cells. These anticancer effects were abolished by 740Y-P.

Conclusions

Grifolin regulates the PI3K/AKT pathway, thus inhibiting lung cancer progression.

Control of cell state transitions by post-transcriptional regulation

Cell state transitions are prevalent in biology, playing a fundamental role in development, homeostasis and repair. Dysregulation of cell state transitions can lead to or occur in a wide range of diseases. In this letter, I explore and highlight the role of post-transcriptional regulatory mechanisms in determining the dynamics of cell state transitions. I propose that regulation of protein levels after transcription provides an under-appreciated regulatory route to obtain fast and sharp transitions between distinct cell states. This article is part of a discussion meeting issue 'Causes and consequences of stochastic processes in development and disease'.

USP8-governed GPX4 homeostasis orchestrates ferroptosis and cancer immunotherapy

Ferroptosis is an iron-dependent type of regulated cell death resulting from extensive lipid peroxidation and plays a critical role in various physiological and pathological processes. However, the regulatory mechanisms for ferroptosis sensitivity remain incompletely understood. Here, we report that homozygous deletion of Usp8 (ubiquitin-specific protease 8) in intestinal epithelial cells (IECs) leads to architectural changes in the colonic epithelium and shortens mouse lifespan accompanied by increased IEC death and signs of lipid peroxidation. However, mice with heterozygous deletion of Usp8 in IECs display normal phenotype and become resistant to azoxymethane/dextran sodium sulfate-induced colorectal tumorigenesis. Mechanistically, USP8 interacts with and deubiquitinates glutathione peroxidase 4 (GPX4), leading to GPX4 stabilization. Thus, USP8 inhibition destabilizes GPX4 and sensitizes cancer cells to ferroptosis in vitro. Notably, USP8 inhibition in combination with ferroptosis inducers retards tumor growth and enhances CD8+ T cell infiltration, which potentiates tumor response to anti-PD-1 immunotherapy in vivo. These findings uncover that USP8 counteracts ferroptosis by stabilizing GPX4 and highlight targeting USP8 as a potential therapeutic strategy to boost ferroptosis for enhancing cancer immunotherapy.

Domains in Action: Understanding Ddi1's Diverse Functions in the Ubiquitin-Proteasome System

The ubiquitin-proteasome system (UPS) is a pivotal cellular mechanism responsible for the selective degradation of proteins, playing an essential role in proteostasis, protein quality control, and regulating various cellular processes, with ubiquitin marking proteins for degradation through a complex, multi-stage process. The shuttle proteins family is a very unique group of proteins that plays an important role in the ubiquitin-proteasome system. Ddi1, Dsk2, and Rad23 are shuttle factors that bind ubiquitinated substrates and deliver them to the 26S proteasome. Besides mediating the delivery of ubiquitinated proteins, they are also involved in many other biological processes. Ddi1, the least-studied shuttle protein, exhibits unique physicochemical properties that allow it to play non-canonical functions in the cells. It regulates cell cycle progression and response to proteasome inhibition and defines MAT type of yeast cells. The Ddi1 contains UBL and UBA domains, which are crucial for binding to proteasome receptors and ubiquitin respectively, but also an additional domain called RVP. Additionally, much evidence has been provided to question whether Ddi1 is a classical shuttle protein. For many years, the true nature of this protein remained unclear. Here, we highlight the recent discoveries, which shed new light on the structure and biological functions of the Ddi1 protein.

TRAIL-induced apoptosis and proteasomal activity - Mechanisms, signalling and interplay

Programmed cell death, in particular apoptosis, is essential during development and tissue homeostasis, and also is the primary strategy to induce cancer cell death by cytotoxic therapies. Precision therapeutics targeting TRAIL death receptors are being evaluated as novel anti-cancer agents, while in parallel highly specific proteasome inhibitors have gained approval as drugs. TRAIL-dependent signalling and proteasomal control of cellular proteostasis are intricate processes, and their interplay can be exploited to enhance therapeutic killing of cancer cells in combination therapies. This review provides detailed insights into the complex signalling of TRAIL-induced pathways and the activities of the proteasome. It explores their core mechanisms of action, pharmaceutical druggability, and describes how their interplay can be strategically leveraged to enhance cell death responses in cancer cells. Offering this comprehensive and timely overview will allow to navigate the complexity of the processes governing cell death mechanisms in TRAIL- and proteasome inhibitor-based treatment conditions.

O-GlcNAcylation of E3 ubiquitin ligase SKP2 promotes hepatocellular carcinoma proliferation

O-linked-β-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) and ubiquitination are critical posttranslational modifications that regulate tumor development and progression. The continuous progression of the cell cycle is the fundamental cause of tumor proliferation. S-phase kinase-associated protein 2 (SKP2), an important E3 ubiquitin ligase, assumes a pivotal function in the regulation of the cell cycle. However, it is still unclear whether SKP2 is an effector of O-GlcNAcylation that affects tumor progression. In this study, we found that SKP2 interacted with O-GlcNAc transferase (OGT) and was highly O-GlcNAcylated in hepatocellular carcinoma (HCC). Mechanistically, the O-GlcNAcylation at Ser34 stabilized SKP2 by reducing its ubiquitination and degradation mediated by APC-CDH1. Moreover, the O-GlcNAcylation of SKP2 enhanced its binding ability with SKP1, thereby enhancing its ubiquitin ligase function. Consequently, SKP2 facilitated the transition from the G1-S phase of the cell cycle by promoting the ubiquitin degradation of cell cycle-dependent kinase inhibitors p27 and p21. Additionally, targeting the O-GlcNAcylation of SKP2 significantly suppressed the proliferation of HCC. Altogether, our findings reveal that O-GlcNAcylation, a novel posttranslational modification of SKP2, plays a crucial role in promoting HCC proliferation, and targeting the O-GlcNAcylation of SKP2 may become a new therapeutic strategy to impede the progression of HCC.

Discovery and characterization of noncanonical E2-conjugating enzymes

E2-conjugating enzymes (E2s) play a central role in the enzymatic cascade that leads to the attachment of ubiquitin to a substrate. This process, termed ubiquitylation, is required to maintain cellular homeostasis and affects almost all cellular process. By interacting with multiple E3 ligases, E2s dictate the ubiquitylation landscape within the cell. Since its discovery, ubiquitylation has been regarded as a posttranslational modification that specifically targets lysine side chains (canonical ubiquitylation). We used Matrix-Assisted Laser Desorption/Ionization-Time Of Flight Mass Spectrometry to identify and characterize a family of E2s that are instead able to conjugate ubiquitin to serine and/or threonine. We used structural modeling and prediction tools to identify the key activity determinants that these E2s use to interact with ubiquitin as well as their substrates. Our results unveil the missing E2s necessary for noncanonical ubiquitylation, underscoring the adaptability and versatility of ubiquitin modifications.

Uncovering Cell Cycle Dysregulations and Associated Mechanisms in Cancer and Neurodegenerative Disorders: A Glimpse of Hope for Repurposed Drugs

The cell cycle is the sequence of events orchestrated by a complex network of cell cycle proteins. Unlike normal cells, mature neurons subsist in a quiescent state of the cell cycle, and aberrant cell cycle activation triggers neuronal death accompanied by neurodegeneration. The periodicity of cell cycle events is choreographed by various mechanisms, including DNA damage repair, oxidative stress, neurotrophin activity, and ubiquitin-mediated degradation. Given the relevance of cell cycle processes in cancer and neurodegeneration, this review delineates the overlapping cell cycle events, signaling pathways, and mechanisms associated with cell cycle aberrations in cancer and the major neurodegenerative disorders. We suggest that dysregulation of some common fundamental signaling processes triggers anomalous cell cycle activation in cancer cells and neurons. We discussed the possible use of cell cycle inhibitors for neurodegenerative disorders and described the associated challenges. We propose that a greater understanding of the common mechanisms driving cell cycle aberrations in cancer and neurodegenerative disorders will open a new avenue for the development of repurposed drugs.

The role of deubiquitinases in cardiac disease

Deubiquitinases are a group of proteins that identify and digest monoubiquitin chains or polyubiquitin chains attached to substrate proteins, preventing the substrate protein from being degraded by the ubiquitin-proteasome system. Deubiquitinases regulate cellular autophagy, metabolism and oxidative stress by acting on different substrate proteins. Recent studies have revealed that deubiquitinases act as a critical regulator in various cardiac diseases, and control the onset and progression of cardiac disease through a board range of mechanism. This review summarizes the function of different deubiquitinases in cardiac disease, including cardiac hypertrophy, myocardial infarction and diabetes mellitus-related cardiac disease. Besides, this review briefly recapitulates the role of deubiquitinases modulators in cardiac disease, providing the potential therapeutic targets in the future.

The cross talk of ubiquitination and chemotherapy tolerance in colorectal cancer

Ubiquitination, a highly adaptable post-translational modification, plays a pivotal role in maintaining cellular protein homeostasis, encompassing cancer chemoresistance-associated proteins. Recent findings have indicated a potential correlation between perturbations in the ubiquitination process and the emergence of drug resistance in CRC cancer. Consequently, numerous studies have spurred the advancement of compounds specifically designed to target ubiquitinates, offering promising prospects for cancer therapy. In this review, we highlight the role of ubiquitination enzymes associated with chemoresistance to chemotherapy via the Wnt/β-catenin signaling pathway, epithelial-mesenchymal transition (EMT), and cell cycle perturbation. In addition, we summarize the application and role of small compounds that target ubiquitination enzymes for CRC treatment, along with the significance of targeting ubiquitination enzymes as potential cancer therapies.

Periodic changes of cyclin D1 mRNA stability are regulated by PC4 modifications in the cell cycle

The cell cycle is a highly regulated process in which proteins involved in cell cycle progression exhibit periodic expression patterns, controlled by specific mechanisms such as transcription, translation, and degradation. However, the precise mechanisms underlying the oscillations of mRNA levels in cell cycle regulators are not fully understood. In this study, we observed that the stability of cyclin D1 (CCND1) mRNA fluctuates during the cell cycle, with increased stability during interphase and decreased stability during the M phase. Additionally, we identified a key RNA binding protein, positive coactivator 4 (PC4), which plays a crucial role in stabilizing CCND1 mRNA and regulating its periodic expression. Moreover, the binding affinity of PC4 to CCND1 mRNA is modulated by two cell cycle-specific posttranslational modifications: ubiquitination of K68 enhances binding and stabilizes the CCND1 transcript during interphase, while phosphorylation of S17 inhibits binding during the M phase, leading to degradation of CCND1 mRNA. Remarkably, PC4 promotes the transition from G1 to S phase in the cell cycle, and depletion of PC4 enhances the efficacy of CDK4/6 inhibitors in hepatocellular carcinoma, suggesting that PC4 could serve as a potential therapeutic target. These findings provide valuable insights into the intricate regulation of cell cycle dynamics.

N/C-degron pathways and inhibitor development for PROTAC applications

Ubiquitination is a fascinating post-translational modification that has received continuous attention since its discovery. In this review, we first provide a concise overview of the E3 ubiquitin ligases, delving into classification, characteristics and mechanisms of ubiquitination. We then specifically examine the ubiquitination pathways mediated by the N/C-degrons, discussing their unique features and substrate recognition mechanisms. Finally, we offer insights into the current state of development pertaining to inhibitors that target the N/C-degron pathways, as well as the promising advances in the field of PROTAC (PROteolysis TArgeting Chimeras). Overall, this review offers a comprehensive understanding of the rapidly-evolving field of ubiquitin biology.