Loss of C9orf72 perturbs the Ran-GTPase gradient and nucleocytoplasmic transport, generating compositionally diverse Importin β-1 granules

A hexanucleotide (GGGGCC)_n repeat expansion in C9orf72 causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), eliciting toxic effects through generation of RNA foci, dipeptide repeat proteins, and/or loss of C9orf72 protein. Defects in nucleocytoplasmic transport (NCT) have been implicated as a pathogenic mechanism underlying repeat expansion toxicity. Here, we show that loss of C9orf72 disrupts the Ran-GTPase gradient and NCT in vitro and in vivo. NCT disruption in vivo is enhanced by the presence of compositionally different types of cytoplasmic Importin β-1 granule that exhibit neuronal subtype-specific properties. We show that the abundance of Importin β-1 granules is increased in the context of C9orf72 deficiency, disrupting interactions with nuclear pore complex proteins. These granules appear to associate with the nuclear envelope and are co-immunoreactive for G3BP1 and K63-ubiquitin. These findings link loss of C9orf72 protein to gain-of-function mechanisms and defects in NCT.

APOBEC3B drives PKR-mediated translation shutdown and protects stress granules in response to viral infection

Double-stranded RNA produced during viral replication and transcription activates both protein kinase R (PKR) and ribonuclease L (RNase L), which limits viral gene expression and replication through host shutoff of translation. In this study, we find that APOBEC3B forms a complex with PABPC1 to stimulate PKR and counterbalances the PKR-suppressing activity of ADAR1 in response to infection by many types of viruses. This leads to translational blockage and the formation of stress granules. Furthermore, we show that APOBEC3B localizes to stress granules through the interaction with PABPC1. APOBEC3B facilitates the formation of protein-RNA condensates with stress granule assembly factor (G3BP1) by protecting mRNA associated with stress granules from RNAse L-induced RNA cleavage during viral infection. These results not only reveal that APOBEC3B is a key regulator of different steps of the innate immune response throughout viral infection but also highlight an alternative mechanism by which APOBEC3B can impact virus replication without editing viral genomes.

From ecology to oncology: To understand cancer stem cell dormancy, ask a Brine shrimp (Artemia)

The brine shrimp (Artemia), releases embryos that can remain dormant for up to a decade. Molecular and cellular level controlling factors of dormancy in Artemia are now being recognized or applied as active controllers of dormancy (quiescence) in cancers. Most notably, the epigenetic regulation by SET domain-containing protein 4 (SETD4), is revealed as highly conserved and the primary control factor governing the maintenance of cellular dormancy from Artemia embryonic cells to cancer stem cells (CSCs). Conversely, DEK, has recently emerged as the primary factor in the control of dormancy exit/reactivation, in both cases. The latter has been now successfully applied to the reactivation of quiescent CSCs, negating their resistance to therapy and leading to their subsequent destruction in mouse models of breast cancer, without recurrence or metastasis potential. In this review, we introduce the many mechanisms of dormancy from Artemia ecology that have been translated into cancer biology, and herald Artemia's arrival on the model organism stage. We show how Artemia studies have unlocked the mechanisms of the maintenance and termination of cellular dormancy. We then discuss how the antagonistic balance of SETD4 and DEK fundamentally controls chromatin structure and consequently governs CSCs function, chemo/radiotherapy resistance, and dormancy in cancers. Many key stages from transcription factors to small RNAs, tRNA trafficking, molecular chaperones, ion channels, and links with various pathways and aspects of signaling are also noted, all of which link studies in Artemia to those of cancer on a molecular and/or cellular level. We particularly emphasize that the application of such emerging factors as SETD4 and DEK may open new and clear avenues for the treatment for various human cancers.

Nsp1 proteins of human coronaviruses HCoV-OC43 and SARS-CoV2 inhibit stress granule formation

Stress granules (SGs) are cytoplasmic condensates that often form as part of the cellular antiviral response. Despite the growing interest in understanding the interplay between SGs and other biological condensates and viral replication, the role of SG formation during coronavirus infection remains poorly understood. Several proteins from different coronaviruses have been shown to suppress SG formation upon overexpression, but there are only a handful of studies analyzing SG formation in coronavirus-infected cells. To better understand SG inhibition by coronaviruses, we analyzed SG formation during infection with the human common cold coronavirus OC43 (HCoV-OC43) and the pandemic SARS-CoV2. We did not observe SG induction in infected cells and both viruses inhibited eukaryotic translation initiation factor 2α (eIF2α) phosphorylation and SG formation induced by exogenous stress. Furthermore, in SARS-CoV2 infected cells we observed a sharp decrease in the levels of SG-nucleating protein G3BP1. Ectopic overexpression of nucleocapsid (N) and non-structural protein 1 (Nsp1) from both HCoV-OC43 and SARS-CoV2 inhibited SG formation. The Nsp1 proteins of both viruses inhibited arsenite-induced eIF2α phosphorylation, and the Nsp1 of SARS-CoV2 alone was sufficient to cause a decrease in G3BP1 levels. This phenotype was dependent on the depletion of cytoplasmic mRNA mediated by Nsp1 and associated with nuclear accumulation of the SG-nucleating protein TIAR. To test the role of G3BP1 in coronavirus replication, we infected cells overexpressing EGFP-tagged G3BP1 with HCoV-OC43 and observed a significant decrease in virus replication compared to control cells expressing EGFP. The antiviral role of G3BP1 and the existence of multiple SG suppression mechanisms that are conserved between HCoV-OC43 and SARS-CoV2 suggest that SG formation may represent an important antiviral host defense that coronaviruses target to ensure efficient replication.

c-Abl Regulates the Pathological Deposition of TDP-43 via Tyrosine 43 Phosphorylation

Non-receptor tyrosine kinase, c-Abl plays a role in the pathogenesis of several neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. Here, we found that TDP-43, which was one of the main proteins comprising pathological deposits in amyotrophic lateral sclerosis (ALS), is a novel substrate for c-Abl. The phosphorylation of tyrosine 43 of TDP-43 by c-Abl led to increased TDP-43 levels in the cytoplasm and increased the formation of G3BP1-positive stress granules in SH-SY5Y cells. The kinase-dead mutant of c-Abl had no effect on the cytoplasmic localization of TDP-43. The expression of phosphor-mimetic mutant Y43E of TDP-43 in primary cortical neurons accumulated the neurite granule. Furthermore, the phosphorylation of TDP-43 at tyrosine 43 by c-Abl promoted the aggregation of TDP-43 and increased neuronal cell death in primary cortical neurons, but not in c-Abl-deficient primary cortical neurons. Identification of c-Abl as the kinase of TDP43 provides new insight into the pathogenesis of ALS.

Stress granules and mTOR are regulated by membrane atg8ylation during lysosomal damage

We report that lysosomal damage is a hitherto unknown inducer of stress granule (SG) formation and that the process termed membrane atg8ylation coordinates SG formation with mTOR inactivation during lysosomal stress. SGs were induced by lysosome-damaging agents including SARS-CoV-2ORF3a, Mycobacterium tuberculosis, and proteopathic tau. During damage, mammalian ATG8s directly interacted with the core SG proteins NUFIP2 and G3BP1. Atg8ylation was needed for their recruitment to damaged lysosomes independently of SG condensates whereupon NUFIP2 contributed to mTOR inactivation via the Ragulator-RagA/B complex. Thus, cells employ membrane atg8ylation to control and coordinate SG and mTOR responses to lysosomal damage.

All-trans retinoic acid (ATRA) regulates key genes in the RARG-TOP2B pathway and reduces anthracycline-induced cardiotoxicity

The effectiveness of anthracycline chemotherapeutics (e.g., doxorubicin) is limited by anthracycline-induced cardiotoxicity (ACT). A nonsynonymous variant (S427L) in the retinoic acid receptor-γ (RARG) gene has been associated with ACT. This variant causes reduced RARG activity, which is hypothesized to lead to increased susceptibility to ACT through reduced activation of the retinoic acid pathway. This study explored the effects of activating the retinoic acid pathway using a RAR-agonist, all-trans retinoic acid (ATRA), in human cardiomyocytes and mice treated with doxorubicin. In human cardiomyocytes, ATRA induced the gene expression of RARs (RARG, RARB) and repressed the expression of topoisomerase II enzyme genes (TOP2A, TOP2B), which encode for the molecular targets of anthracyclines and repressed downstream ACT response genes. Importantly, ATRA enhanced cell survival of human cardiomyocytes exposed to doxorubicin. The protective effect of ATRA was also observed in a mouse model (B6C3F1/J) of ACT, in which ATRA treatment improved heart function compared to doxorubicin-only treated mice. Histological analyses of the heart also indicated that ATRA treatment reduced the pathology associated with ACT. These findings provide additional evidence for the retinoic acid pathway’s role in ACT and suggest that the RAR activator ATRA can modulate this pathway to reduce ACT.

A novel nonsense variant in the CENPP gene segregates in a Swiss family with autosomal dominant low-frequency sensorineural hearing loss

Low-frequency sensorineural hearing loss (SNHL) is a rare hearing impairment affecting frequencies below 1000 Hz, previously associated with DIAPH1, WSF1, MYO7A, TNC, SLC26A4 or CCDC50 genes. By exome sequencing, we report a novel nonsense variant in CENPP gene, segregating low-frequency SNHL in five affected members in a Swiss family with autosomal dominant inheritance pattern. Audiological evaluation showed up-sloping audiometric configuration with mild-to-moderate losses below 1000 Hz, that progresses to high-frequencies over time. Protein modeling shows that the variant truncates five amino acids at the end, losing electrostatic interactions that alter protein stability. CENPP gene is expressed in the supporting cells of the organ of Corti and takes part as a subunit of the Constitutive Centromere Associated Network in the kinetochore, that fixes the centromere to the spindle microtubules. We report CENPP as a new candidate gene for low-frequency SNHL. Further functional characterization might enable us to elucidate its molecular role in SNHL.

Doxorubicin induces prolonged DNA damage signal in cells overexpressing DEK isoform-2

DEK has a short isoform (DEK isoform-2; DEK2) that lacks amino acid residues between 49–82. The full-length DEK (DEK isoform-1; DEK1) is ubiquitously expressed and plays a role in different cellular processes but whether DEK2 is involved in these processes remains elusive. We stably overexpressed DEK2 in human bone marrow stromal cell line HS-27A, in which endogenous DEKs were intact or suppressed via short hairpin RNA (sh-RNA). We have found that contrary to ectopic DEK1, DEK2 locates in the nucleus and nucleolus, causes persistent γH2AX signal upon doxorubicin treatment, and couldn’t functionally compensate for the loss of DEK1. In addition, DEK2 overexpressing cells were more sensitive to doxorubicin than DEK1-cells. Expressions of DEK1 and DEK2 in cell lines and primary tumors exhibit tissue specificity. DEK1 is upregulated in cancers of the colon, liver, and lung compared to normal tissues while both DEK1 and DEK2 are downregulated in subsets of kidney, prostate, and thyroid carcinomas. Interestingly, only DEK2 was downregulated in a subset of breast tumors suggesting that DEK2 can be modulated differently than DEK1 in specific cancers. In summary, our findings show distinct expression patterns and subcellular location and suggest non-overlapping functions between the two DEK isoforms.

p21-activated kinase 2 binds to transcription factor SOX2 and up-regulates DEK to promote the progression of lung squamous cell carcinoma

Lung squamous cell carcinoma (LSCC) is a prevalent and progressive subtype of lung cancer. This study aimed to substantiate the regulatory effect of the PAK2/SOX2/DEK axis on the LSCC development. LSCC tissues (n = 83) and adjacent normal tissues were collected and SOX2 expression was determined by qRT-PCR and Western blotting. Correlation between SOX2 expression and the prognosis of LSCC patients was then explored utilizing Kaplan-Meier analysis. Co-immunoprecipitation and glutathione-S-transferase pull-down assays were conducted to validate the binding of SOX2 to DEK. Gain- and loss- of function assays were then performed on LSCC cells, with CCK-8 and Transwell assays applied to detect the malignant behaviors of cells. A mouse xenograft model of LSCC was further established for in vivo validation. The expression levels of SOX2, PAK2 and DEK were up-regulated in LSCC tissues and cells. SOX2 overexpression was correlated with poor prognosis of LSCC patients. Knockdown of SOX2 weakened the viability and the migratory and invasive potential of LSCC cells. Further, PAK2 directly interacted with SOX2. PAK2 overexpression accelerated the malignant phenotypes of LSCC cells through interplay with SOX2. Moreover, SOX2 activated the expression of DEK, and silencing DEK attenuated the malignant behaviors of LSCC cells. In conclusion, PAK2 could bind to the transcription factor SOX2 and thus activate the expression of DEK, thereby driving the malignant phenotypes of LSCC cells both in vivo and in vitro.

miR-181-5p attenuates neutrophilic inflammation in asthma by targeting DEK

We investigated the regulatory role of miR-181b-5p in neutrophilic asthma and its mechanisms by targeting DEK. DEK, matrix metalloproteinase (MMP)-2, and MMP-9 were overexpressed and the miR-181b-5p was decreased in mice with neutrophilic asthma. DEK was a direct target of miR-181b-5p. In mouse model, miR-181b-5p agomir had an inhibitory effect on airway inflammation and remodeling. miR-181b-5p inhibited DEK/p-GSK-3β^Ser9/β-catenin/MMP-9 pathway activation by regulating Wnt ligands in BEAS-2B and 16HBE cells. The ability of supernatants from human bronchial epithelial cells (hBECs) co-stimulated with CXCL8 (IL-8) and miR-181b-5p to induce NETs was weaker than that of IL-8 alone. Moreover, DEK overexpression led to excessive mitochondrial dysfunction, including DRP1 up-regulation, p-DRP1ser⁶³⁷ and MFN2 down-regulation, mitochondrial membrane potential loss, excessive mtROS generation and mitochondrial incompleteness. Interestingly, all these phenotypes were rescued by Wnt inhibitor DKK-1 and miR-181b-5p agomir. Additionally, inhibition of DRP1 with Mdivi-1 decreased MMP-9 on BEAS-2B cells. Overall, miR-181b-5p could attenuate neutrophilic asthma through inhibition of NETs release, DEK/p-GSK-3β^Ser9/β-catenin/MMP-9 pathway, DEK/Wnt/DRP1/MMP-9 and mitochondria damage. It may become a new therapeutic target for neutrophilic asthma.

Elucidation of TRIM25 ubiquitination targets involved in diverse cellular and antiviral processes

The tripartite motif (TRIM) family of E3 ubiquitin ligases is well known for its roles in antiviral restriction and innate immunity regulation, in addition to many other cellular pathways. In particular, TRIM25-mediated ubiquitination affects both carcinogenesis and antiviral response. While individual substrates have been identified for TRIM25, it remains unclear how it regulates diverse processes. Here we characterized a mutation, R54P, critical for TRIM25 catalytic activity, which we successfully utilized to "trap" substrates. We demonstrated that TRIM25 targets proteins implicated in stress granule formation (G3BP1/2), nonsense-mediated mRNA decay (UPF1), nucleoside synthesis (NME1), and mRNA translation and stability (PABPC4). The R54P mutation abolishes TRIM25 inhibition of alphaviruses independently of the host interferon response, suggesting that this antiviral effect is a direct consequence of ubiquitination. Consistent with that, we observed diminished antiviral activity upon knockdown of several TRIM25-R54P specific interactors including NME1 and PABPC4. Our findings highlight that multiple substrates mediate the cellular and antiviral activities of TRIM25, illustrating the multi-faceted role of this ubiquitination network in modulating diverse biological processes.

Deciphering the endometrial immune landscape of RIF during the window of implantation from cellular senescence by integrated bioinformatics analysis and machine learning

Recurrent implantation failure (RIF) is an extremely thorny issue in in-vitro fertilization (IVF)-embryo transfer (ET). However, its intricate etiology and pathological mechanisms are still unclear. Nowadays, there has been extensive interest in cellular senescence in RIF, and its involvement in endometrial immune characteristics during the window of implantation (WOI) has captured scholars’ growing concerns. Therefore, this study aims to probe into the pathological mechanism of RIF from cellular senescence and investigate the correlation between cellular senescence and endometrial immune characteristics during WOI based on bioinformatics combined with machine learning strategy, so as to elucidate the underlying pathological mechanisms of RIF and to explore novel treatment strategies for RIF. Firstly, the gene sets of GSE26787 and GSE111974 from the Gene Expression Omnibus (GEO) database were included for the weighted gene correlation network analysis (WGCNA), from which we concluded that the genes of the core module were closely related to cell fate decision and immune regulation. Subsequently, we identified 25 cellular senescence-associated differentially expressed genes (DEGs) in RIF by intersecting DEGs with cellular senescence-associated genes from the Cell Senescence (CellAge) database. Moreover, functional enrichment analysis was conducted to further reveal the specific molecular mechanisms by which these molecules regulate cellular senescence and immune pathways. Then, eight signature genes were determined by the machine learning method of support vector machine-recursive feature elimination (SVM-RFE), random forest (RF), and artificial neural network (ANN), comprising LATS1, EHF, DUSP16, ADCK5, PATZ1, DEK, MAP2K1, and ETS2, which were also validated in the testing gene set (GSE106602). Furthermore, distinct immune microenvironment abnormalities in the RIF endometrium during WOI were comprehensively explored and validated in GSE106602, including infiltrating immunocytes, immune function, and the expression profiling of human leukocyte antigen (HLA) genes and immune checkpoint genes. Moreover, the correlation between the eight signature genes with the endometrial immune landscape of RIF was also evaluated. After that, two distinct subtypes with significantly distinct immune infiltration characteristics were identified by consensus clustering analysis based on the eight signature genes. Finally, a “KEGG pathway–RIF signature genes–immune landscape” association network was constructed to intuitively uncover their connection. In conclusion, this study demonstrated that cellular senescence might play a pushing role in the pathological mechanism of RIF, which might be closely related to its impact on the immune microenvironment during the WOI phase. The exploration of the molecular mechanism of cellular senescence in RIF is expected to bring new breakthroughs for disease diagnosis and treatment strategies.

In silico gene expression and pathway analysis of DEK in the human brain across the lifespan

DEK, a chromatin-remodelling phosphoprotein, is associated with various functions and biological pathways in the periphery, including inflammation, oncogenesis, DNA repair, and transcriptional regulation. We recently identified an association between DEK loss and central nervous system diseases, such as Alzheimer's. To understand DEK's potential role in disease, it is critical to characterize DEK in healthy human brain to distinguish between neural DEK expression and function in healthy versus diseased states like dementia. We utilized two public databases, BrainCloud and Human Brain Transcriptome, and analysed DEK mRNA expression across the lifespan in learning and memory relevant brain regions. Since DEK loss induces phenotypes associated with brain ageing (e.g., DNA damage and apoptosis), we hypothesized that neural DEK expression may be highest during foetal development and lower in elderly individuals. In agreement with this hypothesis, DEK was most prominently expressed during foetal development in all queried forebrain areas, relative to other ages. Consistent with its roles in the periphery, pathways related to DEK in the brain were associated with cellular proliferation, DNA replication and repair, apoptosis, and inflammation. We also found novel neural development-relevant pathways (e.g., synaptic transmission, neurite outgrowth, and myelination) to be enriched from genes correlated with DEK expression. These findings suggest that DEK is important for human brain development. Overall, we highlight age-related changes in neural DEK expression across the human lifespan and illuminate novel biological pathways associated with DEK that are distinct from normal brain ageing. These findings may further our understanding of how DEK impacts brain function and disease susceptibility.

Activation of signaling pathways in models of t(6;9)-acute myeloid leukemia

Patients within the WHO-subgroup of t(6;9)-positive acute myeloid leukemia (AML) differ from other AML subgroups as they are characterised by younger age and a grim prognosis. Leukemic transformation can often be attributed to single chromosomal aberrations encoding oncogenes, in the case of t(6;9)-AML to the fusion protein DEK-CAN (also called DEK-NUP214). As being a rare disease there is the urgent need for models of t(6;9)-AML. The only cell line derived from a t(6;9)-AML patient currently available is FKH1. By using phospho-proteomics on FKH1 cells, we found a strongly activated ABL1 kinase. Further investigation revealed the presence of ETV6-ABL1. This finding renders necessary to determine DEK-CAN- and ETV6-ABL1-related features when using FKH1. This can be done as ETV6-ABL1 activity in FKH1 is responsive to imatinib. Nevertheless, we provided evidence that both SFK and mTOR activation in FKH1 are DEK-CAN-related features as they were activated also in other t(6;9) and DEK-CAN-positive models. The activation of STAT5 previously shown to be strong in t(6;9)-AML and activated by DEK-CAN is regulated in FKH1 by both DEK-CAN and ETV6-ABL1. In conclusion, FKH1 cells still represent a model for t(6;9)-AML and could serve as model for ETV6-ABL1-positive AML if the presence of these leukemia-inducing oncogenes is adequately considered.Taken together, all our results provide clear evidence of novel and specific interdependencies between leukemia-inducing oncogenes and cancer signaling pathways which will influence the design of therapeutic strategies to better address the complexity of cancer signaling.

Key Modulators of the Stress Granule Response TIA1, TDP-43, and G3BP1 Are Altered by Polyglutamine-Expanded ATXN7

Spinocerebellar ataxia type 7 (SCA7) and other polyglutamine (polyQ) diseases are caused by expansions of polyQ repeats in disease-specific proteins. Aggregation of the polyQ proteins resulting in various forms of cellular stress, that could induce the stress granule (SG) response, is believed to be a common pathological mechanism in these disorders. SGs can contribute to cell survival but have also been suggested to exacerbate disease pathology by seeding protein aggregation. In this study, we show that two SG-related proteins, TDP-43 and TIA1, are sequestered into the aggregates formed by polyQ-expanded ATXN7 in SCA7 cells. Interestingly, mutant ATXN7 also localises to induced SGs, and this association altered the shape of the SGs. In spite of this, neither the ability to induce nor to disassemble SGs, in response to arsenite stress induction or relief, was affected in SCA7 cells. Moreover, we could not observe any change in the number of ATXN7 aggregates per cell following SG induction, although a small, non-significant, increase in total aggregated ATXN7 material could be detected using filter trap. However, mutant ATXN7 expression in itself increased the speckling of the SG-nucleating protein G3BP1 and the SG response. Taken together, our results indicate that the SG response is induced, and although some key modulators of SGs show altered behaviour, the dynamics of SGs appear normal in the presence of mutant ATXN7.

Pathological complete response to immune checkpoint inhibitor in patients with colorectal cancer liver metastases harboring POLE exonuclease domain mutation

Patients with polymerase epsilon (POLE) exonuclease domain mutation (EDM) exhibits distinct clinical characteristics and extremely high tumor mutation burden (TMB). There is a paucity of data on the therapeutic efficacy of immune checkpoint inhibitors (ICIs) for the treatment of colorectal cancer liver metastases (CRLM) patients with POLE EDM. Clinical characteristics, radiological and pathological response, as well as oncological outcomes of four CRLM patients harboring POLE EDM and treated by ICI plus chemotherapy were retrospectively collected and analyzed. TMB and genomic mutation profiling were also assessed in resected CRLM patients harboring different molecular characteristics. The four CRLM patients received toripalimab or sintilimab plus chemotherapy (FOLFOX or FOLFIRI or XELOX) with or without bevacizumab after POLE EDM were detected. All four patients achieved a radiological partial response. Staged or simultaneous complete surgical resection of the primary tumor and liver metastases was conducted. Pathological complete response was achieved in all four patients. After a median follow-up of 14 (range 9-20) months, all four patients maintained non-evidence of disease status until the last follow-up. POLE EDM patients showed a larger set of mutational genes compared with non-POLE EDM patients. TMB of patients harboring POLE EDM was significantly higher than those with microsatellite instability-high (median, 313.92 vs 42.24 mutations/Mb, p<0.05), POLE non-EDM (313.92 vs 4.80, p<0.001), and MSS subtypes (313.92 vs 4.80, p<0.001). Despite being a rare phenotype, CRLM patients with POLE EDM exhibit ultra-high TMB and, more importantly, significant clinical response to ICI-based combination therapy. Therefore, the complete sequencing of POLE exonuclease domains is recommended in CRLM patients clinically.

DEK modulates both expression and alternative splicing of cancer‑related genes

DEK is known to be a potential proto‑oncogene and is highly expressed in gastric cancer (GC); thus, DEK is considered to contribute to the malignant progression of GC. DEK is an RNA‑binding protein involved in transcription, DNA repair, and selection of splicing sites during mRNA processing; however, its precise function remains elusive due to the lack of clarification of the overall profiles of gene transcription and post‑transcriptional splicing that are regulated by DEK. We performed our original whole‑genomic RNA‑Seq data to analyze the global transcription and alternative splicing profiles in a human GC cell line by comparing DEK siRNA‑treated and control conditions, dissecting both differential gene expression and potential alternative splicing events regulated by DEK. The siRNA‑mediated knockdown of DEK in a GC cell line led to significant changes in gene expression of multiple cancer‑related genes including both oncogenes and tumor suppressors. Moreover, it was revealed that DEK regulated a number of alternative splicing in genes which were significantly enriched in various cancer‑related pathways including apoptosis and cell cycle processes. This study clarified for the first time that DEK has a regulatory effect on the alternative splicing, as well as on the expression, of numerous cancer‑related genes, which is consistent with the role of DEK as a possible oncogene. Our results further expand the importance and feasibility of DEK as a clinical therapeutic target for human malignancies including GC.

Zinc enhances liquid-liquid phase separation of Tau protein and aggravates mitochondrial damages in cells

Intraneuronal neurofibrillary tangles composed of Tau aggregates have been widely accepted as an important pathological hallmark of Alzheimer's disease. Liquid-liquid phase separation (LLPS) of Tau can lead to its aggregation, and Tau aggregation can then be enhanced by zinc. However, it is unclear whether zinc modulates the formation of Tau stress granules in cells. We herein report that zinc promotes the formation of stress granules containing a pathological mutant ΔK280 of full-length human Tau. Furthermore, zinc promotes LLPS of ΔK280 of full-length Tau, shifting the equilibrium phase boundary to a lower protein concentration, and modulates the liquid nature of droplets formed by this pathological mutation. Zinc also promotes pathological phosphorylation of ΔK280 in neuronal cells, and aggravates mitochondrial damage and elevates reactive oxygen species production induced by Tau aggregation. Importantly, we show that treatment of cells with zinc increases the interaction between full-length Tau and G3BP1 inside stress granules to promote the formation of Tau filaments and increase Tau toxicity in neuronal cells. Collectively, these results demonstrate how Tau condensation and mitochondrial damages induced by Tau aggregation are enhanced by zinc to deteriorate the pathogenesis of Alzheimer's disease, bridging the gap between Tau LLPS and aggregation in neuronal cells.

1H, 13C and 15N resonance assignments of stress granule key component G3BP1 RRM domain

G3BP1 exists as a helicase and one of the core components in stress granules, which are associated with a variety of neurodegenerative diseases. Its RNA recognition motif (RRM) domain performs the paramount function of binding mRNA. Here we report the resonance assignment of human G3BP1 RRM domain to understand its structure-function relationship.

Exosomal DEK removes chemoradiotherapy resistance by triggering quiescence exit of breast cancer stem cells

Tumor therapeutics often target the primary tumor bulk but fail to eradicate therapy-resistant cancer stem cells (CSCs) in quiescent state. These can then become activated to initiate recurrence and/or metastasis beyond therapy. Here, we identified and isolated chemoradiotherapy-resistant CSCs in quiescent state with high capacity of tumor-initiation and tumorsphere formation from three types of breast tumors in mice. Experiments of knockdown and rescue revealed DEK, a nuclear protein, as essential for CSC activation. Exogenous DEK was then used to trigger quiescence exit of CSCs. ChIP-seq and ATAC-seq showed that DEK directly binds to chromatin, facilitating its genome-wide accessibility. The resulting epigenetic events upregulate the expression of cellular activation-related genes including MYC targets, whereas cellular quiescence-related genes including the p53 signaling pathway are silenced. However, twinned with DEK-induced activation, formerly resistant CSCs were then destroyed by chemotherapy in vitro. In mice, traditional chemoradiotherapy concurrent with the injection of DEK-containing exosomes resulted in eradication of primary tumors together with formerly resistant CSCs without recurrence or metastasis. Our findings advance knowledge of the mechanism of quiescent CSC activation and may provide novel clinical opportunities for removal of quiescence-linked therapy resistance.

Noncanonical HIPPO/MST Signaling via BUB3 and FOXO Drives Pulmonary Vascular Cell Growth and Survival

RATIONALE

The MSTs (mammalian Ste20-like kinases) 1/2 are members of the HIPPO pathway that act as growth suppressors in adult proliferative diseases. Pulmonary arterial hypertension (PAH) manifests by increased proliferation and survival of pulmonary vascular cells in small PAs, pulmonary vascular remodeling, and the rise of pulmonary arterial pressure. The role of MST1/2 in PAH is currently unknown.

OBJECTIVE

To investigate the roles and mechanisms of the action of MST1 and MST2 in PAH.

METHODS AND RESULTS

Using early-passage pulmonary vascular cells from PAH and nondiseased lungs and mice with smooth muscle-specific tamoxifen-inducible Mst1/2 knockdown, we found that, in contrast to canonical antiproliferative/proapoptotic roles, MST1/2 act as proproliferative/prosurvival molecules in human PAH pulmonary arterial vascular smooth muscle cells and pulmonary arterial adventitial fibroblasts and support established pulmonary vascular remodeling and pulmonary hypertension in mice with SU5416/hypoxia-induced pulmonary hypertension. By using unbiased proteomic analysis, gain- and loss-of function approaches, and pharmacological inhibition of MST1/2 kinase activity by XMU-MP-1, we next evaluated mechanisms of regulation and function of MST1/2 in PAH pulmonary vascular cells. We found that, in PAH pulmonary arterial adventitial fibroblasts, the proproliferative function of MST1/2 is caused by IL-6-dependent MST1/2 overexpression, which induces PSMC6-dependent downregulation of forkhead homeobox type O 3 and hyperproliferation. In PAH pulmonary arterial vascular smooth muscle cells, MST1/2 acted via forming a disease-specific interaction with BUB3 and supported ECM (extracellular matrix)- and USP10-dependent BUB3 accumulation, upregulation of Akt-mTORC1, cell proliferation, and survival. Supporting our in vitro observations, smooth muscle-specific Mst1/2 knockdown halted upregulation of Akt-mTORC1 in small muscular PAs of mice with SU5416/hypoxia-induced pulmonary hypertension.

CONCLUSIONS

Together, this study describes a novel proproliferative/prosurvival role of MST1/2 in PAH pulmonary vasculature, provides a novel mechanistic link from MST1/2 via BUB3 and forkhead homeobox type O to the abnormal proliferation and survival of pulmonary arterial vascular smooth muscle cells and pulmonary arterial adventitial fibroblasts, remodeling and pulmonary hypertension, and suggests new target pathways for therapeutic intervention.

The clinicopathology and survival characteristics of patients with POLE proofreading mutations in endometrial carcinoma: A systematic review and meta-analysis

Background

Endometrial carcinoma (EC) is classified into four distinct molecular subgroups. Patients with polymerase epsilon exonuclease domain mutated (POLE-EDM) tumors have the best prognosis of all. This meta-analysis consolidated the clinicopathology variations reported in the POLE-mutant subtype and survival parameters in patients with EC.

Methods

The following internet data bases were searched: PubMed, Web of science, Embase and Scimage directory. Data was extracted from eligible studies including sample size, number of positive POLE-mutant cases, EDM sequencing information, clinicopathologic, and survival data. Meta-analysis and a random-effects model produced pooled estimates of POLE prognostic parameters using 95% confidence intervals (CI), hazard ratios (HR), and odds ratios (OR).

Results

The meta-analysis included 11 cohort studies comprising 5508 EC patients (442 POLE EDM tumors). Patients with POLE mutant EC were associated with improved disease specific survival (HR = 0.408, 95% CI: 0.306 to 0.543) and progression-free survival (HR = 0.231, 95% CI: 0.117 to 0.456). POLE-mutated tumors were mostly endometrioid histology (84.480%; 95% CI: 77.237 to 90.548), although not significantly more than wild type tumors (OR = 1.386; p = 0.073). The POLE mutant tumors significantly present (p<0.001) at Federation of International of Gynecologists and Obstetricians (FIGO) lower stages I-II (OR = 2.955, p<0.001) and highest grade III (OR = 1.717, P = 0.003). The tumors are significantly associated with invasion less than half (<50%) of the myometrium (OR = 1.765, p = 0.001), but not deeply invasive EC (MI>50%, OR = 0.83, p = 0.34). POLE mutations significantly protected against lymph node metastases (OR = 0.202, p = 0.001), and have no clear association with lymph-vascular space invasion (OR = 0.967, 95% 0.713–1.310, p = 0.826). The tumors are predominantly of low ESMO risk stratification distribution (40.356%; 95% CI: 27.577 to 53.838).

Conclusions

POLE mutations serve as an important biomarker of favorable prognosis in EC. The tumors are characteristically high grade, early stage, and remain localized in the endometrium with reduced likelihood of lymph node metastasis for improved survival prospects and the lowest risk classification. These findings have implications for medical management of EC.

Integrated Bioinformatics Analysis for Identification of the Hub Genes Linked with Prognosis of Ovarian Cancer Patients

BACKGROUND

One of the most usual gynecological state of tumor is ovarian cancer and is a major reason of gynecological tumor-related global mortality rate. There have been multiple risk elements related to ovarian cancer like the background of past cases associated with breast cancer or ovarian cancer, or excessive body weight issues, case history of smoking, and untimely menstruation or menopause. Because of unclear expressions, more than 70% of the ovarian cancer patient cases are determined during the early stage. Material and Methods. GSE38666, GSE40595, and GSE66957 were the three microarray datasets which were analyzed using GEO2R for screening the differentially expressed genes. GO, Kyoto Encyclopedia of Genes, and protein expression studies were performed for analysis of hub genes. Then, survival analysis was performed for all the hub genes.

RESULTS

From the dataset, a total of 199 differentially expressed genes (DEGs) were identified. Through the KEGG pathway study, it was noted that the DEGs are mainly linked with the AGE-RAGE signaling pathway, central carbon metabolism, and human papillomavirus infection. The survival analysis showed 4 highly expressed hub genes COL4A1, SDC1, CDKN2A, and TOP2A which correlated with overall survival in ovarian cancer patients. Moreover, the expression of the 4 hub genes was validated by the GEPIA database and the Human Protein Atlas.

CONCLUSION

The results have shown that all 4 hub genes were found to be upregulated in ovarian cancer tissues which predict poor prognosis in patients with ovarian cancer.

The stress granule protein G3BP1 promotes pre-condensation of cGAS to allow rapid responses to DNA

Cyclic GMP-AMP synthase (cGAS) functions as a key sensor for microbial invasion and cellular damage by detecting emerging cytosolic DNA. Here, we report that GTPase-activating protein-(SH3 domain)-binding protein 1 (G3BP1) primes cGAS for its prompt activation by engaging cGAS in a primary liquid-phase condensation state. Using high-resolution microscopy, we show that in resting cells, cGAS exhibits particle-like morphological characteristics, which are markedly weakened when G3BP1 is deleted. Upon DNA challenge, the pre-condensed cGAS undergoes liquid-liquid phase separation (LLPS) more efficiently. Importantly, G3BP1 deficiency or its inhibition dramatically diminishes DNA-induced LLPS and the subsequent activation of cGAS. Interestingly, RNA, previously reported to form condensates with cGAS, does not activate cGAS. Accordingly, we find that DNA - but not RNA - treatment leads to the dissociation of G3BP1 from cGAS. Taken together, our study shows that the primary condensation state of cGAS is critical for its rapid response to DNA.