Phylogenetic relationships and genetic diversity of the Korean endemic Phedimus latiovalifolius (Crassulaceae) and its close relatives.

Phedimus latiovalifolius (Y.N.Lee) D.C.Son & H.J.Kim is exclusively distributed in the high mountains in the Korean Peninsula, mainly along the Baekdudaegan mountain range. Despite its morphological and distributional distinction from other Phedimus Raf. species, its taxonomic identity and phylogenetic relationship with congeneric species remain unclear. This study employs genotyping-by-sequencing-derived genome-wide single nucleotide polymorphisms to establish the monophyly of P. latiovalifolius and its relationship with closely related species. Genetic diversity and population differentiation of P. latiovalifolius are also assessed to provide baseline genetic information for future conservation and management strategies. Our phylogenetic analyses robustly demonstrate the monophyletic nature of P. latiovalifolius, with P. aizoon (L.) 't Hart identified as its closest sister lineage. There is no genetic evidence supporting a hybrid origin of P. latiovalifolius from P. aizoon involving either P. ellacombeanus (Praeger) 't Hart or P. kamtschaticus (Fisch.) 't Hart. Population genetic analyses reveal two major groups within P. latiovalifolius. A higher genetic variation is observed in P. ellacombeanus than in the congeneric species. Notably, most of the genetic variation exists within P. latiovalifolius populations. Given its distribution and the potential role of Baekdudaegan as an East Asian Pleistocene refugia, P. latiovalifolius could be considered rare and endemic, persisting in the refugium across glacial/interglacial cycles.

Entosis implicates a new role for P53 in microcephaly pathogenesis, beyond apoptosis.

Entosis, a form of cell cannibalism, is a newly discovered pathogenic mechanism leading to the development of small brains, termed microcephaly, in which P53 activation was found to play a major role. Microcephaly with entosis, found in Pals1 mutant mice, displays P53 activation that promotes entosis and apoptotic cell death. This previously unappreciated pathogenic mechanism represents a novel cellular dynamic in dividing cortical progenitors which is responsible for cell loss. To date, various recent models of microcephaly have bolstered the importance of P53 activation in cell death leading to microcephaly. P53 activation caused by mitotic delay or DNA damage manifests apoptotic cell death which can be suppressed by P53 removal in these animal models. Such genetic studies attest P53 activation as quality control meant to eliminate genomically unfit cells with minimal involvement in the actual function of microcephaly associated genes. In this review, we summarize the known role of P53 activation in a variety of microcephaly models and introduce a novel mechanism wherein entotic cell cannibalism in neural progenitors is triggered by P53 activation.

SARS-CoV-2 infection exacerbates the cellular pathology of Parkinson's disease in human dopaminergic neurons and a mouse model.

While an association between Parkinson's disease (PD) and viral infections has been recognized, the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on PD progression remains unclear. Here, we demonstrate that SARS-CoV-2 infection heightens the risk of PD using human embryonic stem cell (hESC)-derived dopaminergic (DA) neurons and a human angiotensin-converting enzyme 2 (hACE2) transgenic (Tg) mouse model. Our findings reveal that SARS-CoV-2 infection exacerbates PD susceptibility and cellular toxicity in DA neurons pre-treated with human preformed fibrils (hPFFs). Additionally, nasally delivered SARS-CoV-2 infects DA neurons in hACE2 Tg mice, aggravating the damage initiated by hPFFs. Mice infected with SARS-CoV-2 display persisting neuroinflammation even after the virus is no longer detectable in the brain. A comprehensive analysis suggests that the inflammatory response mediated by astrocytes and microglia could contribute to increased PD susceptibility associated with SARS-CoV-2. These findings advance our understanding of the potential long-term effects of SARS-CoV-2 infection on the progression of PD.

The autoimmune response induced by α-synuclein peptides drives neuronal cell death and glial cell activation.

Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with the loss of dopaminergic neurons and neuroinflammation. Recent studies have identified a role of T cells in the pathogenesis of PD. Additionally, these studies suggested that α-synuclein (α-Syn) is related to abnormal T-cell responses and may act as an epitope and trigger autoimmune T-cell responses. However, it is unclear whether the α-Syn-mediated autoimmune response occurs and whether it is related to neuronal cell death and glial cell activation. In this study, we investigated the autoimmune T-cell response induced by α-Syn peptides and evaluated the neurotoxic effect of the α-Syn peptide-mediated autoimmune response. The immunization of mice with α-Syn peptides resulted in enhanced autoimmune responses, such as the peptide recall response, polarization toward Th1/Th17 cells, and regulatory T cell imbalance. Furthermore, the α-Syn autoimmune response led to the death of primary neurons cocultured with splenocytes. Treatment with conditioned media from α-Syn peptide-immunized splenocytes induced microglia and toxic A1-type astrocyte activation. Taken together, our results provide evidence of the potential role of the α-Syn-initiated autoimmune response and its contribution to neuronal cell death and glial cell activation.

Chloroplast Genome Provides Insights into Molecular Evolution and Species Relationship of Fleabanes (Erigeron: Tribe Astereae, Asteraceae) in the Juan Fernández Islands, Chile.

Erigeron represents the third largest genus on the Juan Fernández Islands, with six endemic species, five of which occur exclusively on the younger Alejandro Selkirk Island with one species on both islands. While its continental sister species is unknown, Erigeron on the Juan Fernández Islands appears to be monophyletic and most likely evolved from South American progenitor species. We characterized the complete chloroplast genomes of five Erigeron species, including accessions of E. fernandezia and one each from Alejandro Selkirk and Robinson Crusoe Islands, with the purposes of elucidating molecular evolution and phylogenetic relationships. We found highly conserved chloroplast genomes in size, gene order and contents, and further identified several mutation hotspot regions. In addition, we found two positively selected chloroplast genes (ccsA and ndhF) among species in the islands. The complete plastome sequences confirmed the monophyly of Erigeron in the islands and corroborated previous phylogenetic relationships among species. New findings in the current study include (1) two major lineages, E. turricola-E. luteoviridis and E. fernandezia-E. ingae-E. rupicola, (2) the non-monophyly of E. fernandezia occurring on the two islands, and (3) the non-monophyly of the alpine species E. ingae complex.

The artificial amino acid change in the sialic acid-binding domain of the hemagglutinin neuraminidase of newcastle disease virus increases its specificity to HCT 116 colorectal cancer cells and tumor suppression effect.

BACKGROUND: Oncolytic viruses are being studied and developed as novel cancer treatments. Using directed evolution technology, structural modification of the viral surface protein increases the specificity of the oncolytic virus for a particular cancer cell. Newcastle disease virus (NDV) does not show specificity for certain types of cancer cells during infection; therefore, it has low cancer cell specificity. Hemagglutinin is an NDV receptor-binding protein on the cell surface that determines host cell tropism. NDV selectivity for specific cancer cells can be increased by artificial amino acid changes in hemagglutinin neuraminidase HN proteins via directed evolution, leading to improved therapeutic effects. METHODS: Sialic acid-binding sites (H domains) of the HN protein mutant library were generated using error-prone PCR. Variants of the H domain protein were screened by enzyme-linked immunosorbent assay using HCT 116 cancer cell surface molecules. The mutant S519G H domain protein showed the highest affinity for the surface protein of HCT 116 cells compared to that of different types of cancer cells. This showed that the S519G mutant H domain protein gene replaced the same part of the original HN protein gene, and S519G mutant recombinant NDV (rNDV) was constructed and recovered. S519G rNDV cancer cell killing effects were tested using the MTT assay with various cancer cell types, and the tumor suppression effect of the S519G mutant rNDV was tested in a xenograft mouse model implanted with cancer cells, including HCT 116 cells. RESULTS: S519G rNDV showed increased specificity and enhanced killing ability of HCT 116 cells among various cancer cells and a stronger suppressive effect on tumor growth than the original recombinant NDV. Directed evolution using an artificial amino acid change in the NDV HN (S519G mutant) protein increased its specificity and oncolytic effect in colorectal cancer without changing its virulence. CONCLUSION: These results provide a new methodology for the use of directed evolution technology for more effective oncolytic virus development.

Effects of 3S business intelligence systems for nursing students: a repeated-measures randomized control trial.

BACKGROUND: The growing need for healthcare services as a result of a consistently rising prevalence of chronic diseases and rapid population aging calls for a new set of activities and practices. Therefore, we developed a program-3S (Simple, Smart, and Speed) Business Intelligence Systems (3S-BIS), which is an ERP software system that helps nursing business to support nursing entrepreneurship -and analyzed its effects on nursing students. METHODS: A repeated-measures randomized controlled trial was performed with two groups: experimental (n = 29) and control (n = 30) groups. The former group underwent the five-day 3S-BIS education program. Each session comprised four components: lectures 1 and 2, simulation case study, and debriefing. Post-tests were performed immediately post-intervention and four and eight weeks later. The effectiveness was measured using the following variables: simulation design assessment, evaluation of educational practices in simulation, education satisfaction, self-efficacy for learning, and entrepreneurship. The differences before and after intervention between the experimental and control groups were analyzed using the Friedman test. The Mann-Whitney U test was used for comparisons between groups at each time point, and the Wilcoxon signed-rank test was used for comparisons within groups at each time point. RESULTS: Post-intervention (8 weeks after intervention), the experimental group demonstrated higher simulation design assessment (z = -3.88, p = < .001), evaluation of educational practices in simulation (z = -3.34, p = .001), education satisfaction (z = -3.11, p = .002), self-efficacy for learning (z = -3.04, p = .002), and entrepreneurship (z = -2.15, p = .031) compared to controls. Furthermore, simulation design assessment score in the experimental group significantly differed between T1 (immediately after intervention) and T0 (baseline), and between T3 (8 weeks after intervention) and T0. Evaluation of educational practices in the simulation, education satisfaction, and self-efficacy also significantly differed between T1 and T0, and between T3 and T0. Entrepreneurship significantly differed between T3 and T2 (4 weeks after intervention), and between T3 and T0. CONCLUSIONS: The 3S-BIS program contributes to enhancing nursing start-up competency. Subsequent studies should evaluate the effects of the program on nurses who work in home healthcare services.

P53 independent pathogenic mechanisms contribute to BubR1 microcephaly.

The mosaic variegated aneuploidy (MVA)-associated gene Budding Uninhibited by Benzimidazole 1B (BUB1B) encodes BUBR1, a core member of the spindle assembly checkpoint complex that ensures kinetochore-spindle attachment for faithful chromosome segregation. BUB1B mutation in humans and its deletion in mice cause microcephaly. In the absence of BubR1 in mice, massive cell death reduces cortical cells during neurogenesis. However, the molecular and cellular mechanisms triggering cell death are unknown. In this study, we performed three-dimensional imaging analysis of mitotic BubR1-deficient neural progenitors in a murine model to show profound chromosomal segregation defects and structural abnormalities. Chromosomal defects and accompanying DNA damage result in P53 activation and apoptotic cell death in BubR1 mutants. To test whether the P53 cell death pathway is responsible for cortical cell loss, we co-deleted Trp53 in BubR1-deficient cortices. Remarkably, we discovered that residual apoptotic cell death remains in double mutants lacking P53, suggesting P53-independent apoptosis. Furthermore, the minimal rescue of cortical size and cortical neuron numbers in double mutant mice suggests the compelling extent of alternative death mechanisms in the absence of P53. This study demonstrates a potential pathogenic mechanism for microcephaly in MVA patients and uncovers the existence of powerful means of eliminating unfit cells even when the P53 death pathway is disabled.

The tumor suppressive effect and apoptotic mechanism of TRAIL gene-containing recombinant NDV in TRAIL-resistant colorectal cancer HT-29 cells and TRAIL-nonresistant HCT116 cells, with each cell bearing a mouse model.

BACKGROUND: TRAIL is an anticancer drug that induces cancer cell apoptosis by interacting with death receptors (DRs). However, owing to low cell-surface expression of DRs, certain colorectal cancer (CRC) cells resist TRAIL-induced apoptosis. Newcastle disease virus (NDV) infection can elevate DR protein expression in cancer cells, potentially influencing their TRAIL sensitivity. However, the precise mechanism by which NDV infection modulates DR expression and impacts TRAIL sensitivity in cancer cells remains unknown. METHODS: Herein, we developed nonpathogenic NDV VG/GA strain-based recombinant NDV (rNDV) and TRAIL gene-containing rNDV (rNDV-TRAIL). We observed that viral infections lead to increased DR and TRAIL expressions and activate signaling proteins involved in intrinsic and extrinsic apoptosis pathways. Experiments were conducted in vitro using TRAIL-resistant CRC cells (HT-29) and nonresistant CRC cells (HCT116) and in vivo using relevant mouse models. RESULTS: rNDV-TRAIL was found to exhibit better apoptotic efficacy than rNDV in CRC cells. Notably, rNDV-TRAIL had the stronger cancer cell-killing effect in TRAIL-resistant CRC cells. Western blot analyses showed that both rNDV and rNDV-TRAIL infections activate signaling proteins involved in the intrinsic and extrinsic apoptotic pathways. Notably, rNDV-TRAIL promotes concurrent intrinsic and extrinsic signal transduction in both HCT-116 and HT-29 cells. CONCLUSIONS: Therefore, rNDV-TRAIL infection effectively enhances DR expression in DR-depressed HT-29 cells. Moreover, the TRAIL protein expressed by rNDV-TRAIL effectively interacts with DR, leading to enhanced apoptosis in TRAIL-resistant HT-29 cells. Therefore, rNDV-TRAIL has potential as a promising therapeutic approach for treating TRAIL-resistant cancers.

Cross-Activation of Regulatory T Cells by Self Antigens Limits Self-Reactive and Activated CD8+ T Cell Responses.

The interaction between regulatory T (Treg) cells and self-reactive T cells is a crucial mechanism for maintaining immune tolerance. In this study, we investigated the cross-activation of Treg cells by self-antigens and its impact on self-reactive CD8+ T cell responses, with a focus on the P53 signaling pathway. We discovered that major histocompatibility complex (MHC) I-restricted self-peptides not only activated CD8+ T cells but also induced the delayed proliferation of Treg cells. Following HLA-A*0201-restricted Melan-A-specific (pMelan) CD8+ T cells, we observed the direct expansion of Treg cells and concurrent suppression of pMelan+CD8+ T cell proliferation upon stimulation with Melan-A peptide. Transcriptome analysis revealed no significant alterations in specific signaling pathways in pMelan+CD8+ T cells that were co-cultured with activated Treg cells. However, there was a noticeable upregulation of genes involved in P53 accumulation, a critical regulator of cell survival and apoptosis. Consistent with such observation, the blockade of P53 induced a continuous proliferation of pMelan+CD8+ T cells. The concurrent stimulation of Treg cells through self-reactive TCRs by self-antigens provides insights into the immune system's ability to control activated self-reactive CD8+ T cells as part of peripheral tolerance, highlighting the intricate interplay between Treg cells and CD8+ T cells and implicating therapeutic interventions in autoimmune diseases and cancer immunotherapy.

Neuroinvasion and anosmia are independent phenomena upon infection with SARS-CoV-2 and its variants.

Anosmia was identified as a hallmark of COVID-19 early in the pandemic, however, with the emergence of variants of concern, the clinical profile induced by SARS-CoV-2 infection has changed, with anosmia being less frequent. Here, we assessed the clinical, olfactory and neuroinflammatory conditions of golden hamsters infected with the original Wuhan SARS-CoV-2 strain, its isogenic ORF7-deletion mutant and three variants: Gamma, Delta, and Omicron/BA.1. We show that infected animals develop a variant-dependent clinical disease including anosmia, and that the ORF7 of SARS-CoV-2 contributes to the induction of olfactory dysfunction. Conversely, all SARS-CoV-2 variants are neuroinvasive, regardless of the clinical presentation they induce. Taken together, this confirms that neuroinvasion and anosmia are independent phenomena upon SARS-CoV-2 infection. Using newly generated nanoluciferase-expressing SARS-CoV-2, we validate the olfactory pathway as a major entry point into the brain in vivo and demonstrate in vitro that SARS-CoV-2 travels retrogradely and anterogradely along axons in microfluidic neuron-epithelial networks.

CRIF1 siRNA-Encapsulated PLGA Nanoparticles Suppress Tumor Growth in MCF-7 Human Breast Cancer Cells.

Mitochondrial oxidative phosphorylation (OXPHOS) system dysfunction in cancer cells has been exploited as a target for anti-cancer therapeutic intervention. The downregulation of CR6-interacting factor 1 (CRIF1), an essential mito-ribosomal factor, can impair mitochondrial function in various cell types. In this study, we investigated whether CRIF1 deficiency induced by siRNA and siRNA nanoparticles could suppress MCF-7 breast cancer growth and tumor development, respectively. Our results showed that CRIF1 silencing decreased the assembly of mitochondrial OXPHOS complexes I and II, which induced mitochondrial dysfunction, mitochondrial reactive oxygen species (ROS) production, mitochondrial membrane potential depolarization, and excessive mitochondrial fission. CRIF1 inhibition reduced p53-induced glycolysis and apoptosis regulator (TIGAR) expression, as well as NADPH synthesis, leading to additional increases in ROS production. The downregulation of CRIF1 suppressed cell proliferation and inhibited cell migration through the induction of G0/G1 phase cell cycle arrest in MCF-7 breast cancer cells. Similarly, the intratumoral injection of CRIF1 siRNA-encapsulated PLGA nanoparticles inhibited tumor growth, downregulated the assembly of mitochondrial OXPHOS complexes I and II, and induced the expression of cell cycle protein markers (p53, p21, and p16) in MCF-7 xenograft mice. Thus, the inhibition of mitochondrial OXPHOS protein synthesis through CRIF1 deletion destroyed mitochondrial function, leading to elevated ROS levels and inducing antitumor effects in MCF-7 cells.

New insights into the phylogenetic relationships among wild onions (Allium, Amaryllidaceae), with special emphasis on the subgenera Anguinum and Rhizirideum, as revealed by plastomes.

The genus Allium, with over 900 species, is one of the largest monocotyledonous genera and is widely accepted with 15 recognized subgenera and 72 sections. The robust subgeneric and sectional relationships within Allium have long been not resolved. Based on 76 species of Allium (a total of 84 accessions), we developed a highly resolved plastome phylogenetic framework by integrating 18 newly sequenced species (20 accessions) in this study and assessed their subgeneric and sectional relationships, with special emphasis on the two subgenera Anguinum and Rhizirideum. We retrieved the three major evolutionary lines within Allium and found that the two subgenera Anguinum and Rhizirideum are monophyletic whereas others are highly polyphyletic (e.g., Allium, Cepa, Polyprason, and Melanocrommyum). Within the subgenus Anguinum, two strongly supported sublineages in East Asian and Eurasian-American were found. Allium tricoccum in North America belonged to the Eurasian clade. The distinct taxonomic status of A. ulleungense and its sister taxon were further determined. In subg. Rhizirideum, the Ulleung Island endemic A. dumebuchum shared its most recent common ancestor with the species from Mongolia and the narrow Korean endemic A. minus. Two Ulleung Island endemics were estimated to originate independently during the Pleistocene. In addition, a separate monotypic sectional treatment of the east Asian A. macrostemon (subg. Allium) and sister relationship between A. condensatum and A. chinense was suggested.

Plastome-based backbone phylogeny of East Asian Phedimus (Subgenus Aizoon: Crassulaceae), with special emphasis on Korean endemics.

Although the monophyly of Phedimus has been strongly demonstrated, the species relationships among approximately 20 species of Phedimus have been difficult to determine because of the uniformity of their floral characteristics and extreme variation of their vegetative characters, often accompanied by high polyploid and aneuploid series and diverse habitats. In this study, we assembled 15 complete chloroplast genomes of Phedimus species from East Asia and generated a plastome-based backbone phylogeny of the subgenus Aizoon. As a proxy for nuclear phylogeny, we reconstructed the nuclear ribosomal DNA internal transcribed spacer (nrDNA ITS) phylogeny independently. The 15 plastomes of subg. Aizoon were highly conserved in structure and organization; hence, the complete plastome phylogeny fully resolved the species relationships with strong support. We found that P. aizoon and P. kamtschaticus were polyphyletic and morphologically distinct or ambiguous species, and they most likely evolved from the two species complex. The crown age of subg. Aizoon was estimated to be 27 Ma, suggesting its origin to be in the late Oligocene; however, the major lineages were diversified during the Miocene. The two Korean endemics, P. takesimensis and P. zokuriensis, were inferred to have originated recently during the Pleistocene, whereas the other endemic, P. latiovalifolium, originated in the late Miocene. Several mutation hotspots and seven positively selected chloroplast genes were identified in the subg. Aizoon.

IDH2 Deficiency Promotes Endothelial Senescence by Eliciting miR-34b/c-Mediated Suppression of Mitophagy and Increased ROS Production.

Endothelial senescence impairs vascular function and thus is a primary event of age-related vasculature diseases. Isocitrate dehydrogenase 2 (IDH2) plays an important role in inducing alpha-ketoglutarate (α-KG) production and preserving mitochondrial function. However, the mechanism and regulation of IDH2 in endothelial senescence have not been elucidated. We demonstrated that downregulation of IDH2 induced accumulation of miR-34b/c, which impaired mitophagy and elevated mitochondrial reactive oxygen species (ROS) levels by inhibiting mitophagy-related markers (PTEN-induced putative kinase 1 (PINK1), Parkin, LC-II/LC3-I, and p62) and attenuating Sirtuin deacetylation 3 (Sirt3) expression. The mitochondrial dysfunction induced by IDH2 deficiency disrupted cell homeostasis and the cell cycle and led to endothelial senescence. However, miR-34b/c inhibition or α-KG supplementation restored Sirt3, PINK1, Parkin, LC-II/LC3-I, p62, and mitochondrial ROS levels, subsequently alleviating endothelial senescence. We showed that IDH2 played a crucial role in regulating endothelial senescence via induction of miR-34b/c in endothelial cells.

An entosis-like process induces mitotic disruption in Pals1 microcephaly pathogenesis.

Entosis is cell cannibalism utilized by tumor cells to engulf live neighboring cells for pro- or anti-tumorigenic purposes. It is unknown whether this extraordinary cellular event can be pathogenic in other diseases such as microcephaly, a condition characterized by a smaller than normal brain at birth. We find that mice mutant for the human microcephaly-causing gene Pals1, which exhibit diminished cortices due to massive cell death, also exhibit nuclei enveloped by plasma membranes inside of dividing cells. These cell-in-cell (CIC) structures represent a dynamic process accompanied by lengthened mitosis and cytokinesis abnormalities. As shown in tumor cells, ROCK inhibition completely abrogates CIC structures and restores the normal length of mitosis. Moreover, genetic elimination of Trp53 produces a remarkable rescue of cortical size along with substantial reductions of CIC structures and cell death. These results provide a novel pathogenic mechanism by which microcephaly is produced through entotic cell cannibalism.

Identifying the suicidal ideation risk group among older adults in rural areas: Developing a predictive model using machine learning methods.

AIMS: The aim of this study was to develop a predictive model that can identify the suicidal ideation risk group among older adults in rural areas using machine learning methods. DESIGN: This study applied an exploratory, descriptive and cross-sectional design. METHODS: The participants were older adults (N = 650) aged over 65 living in rural areas of South Korea. Self-report questionnaires were used to collect the demographics, suicidal ideation, depression, socioeconomic information and basic health information from September to October 2020. The collected data were analysed using machine learning methods with R statistical software 4.1.0. RESULTS: The predictive models indicated that depression, pain, age and loneliness were significant factors of suicidal ideation. Good performance was observed based on the area under the receiver operating characteristic curve in the decision tree, random forest and logistic regression. Finally, the evaluation of model performance indicated moderate to high sensitivity and specificity. CONCLUSION: The predictive models using machine learning methods may be useful to predict the risk of suicidal ideation. Furthermore, depression with pain, age and feelings of loneliness should be included in the initial screening to assess suicide risk among older adults in rural areas. IMPACT: Identifying suicidal risk among older adults is challenging. Thus, employing predictive models that can assess depression, pain, age and loneliness can enable public healthcare providers to detect suicidal risk groups. Particularly, the presented models from this study can facilitate healthcare providers with initiating early interventions to prevent suicide among older adults in clinical and community nursing care settings. REPORTING METHOD: The reporting of this study (Observational, cross-sectional study) conforms to the STROBE statement. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution. This study did not involve patients, service users, caregivers or members of the public. IMPLICATION FOR THE PROFESSION AND/OR PATIENTS CARE: Applying this model may help to prevent geriatric suicide because the nursing staff will have a greater awareness regarding the suicide ideation risk of older adults, thereby reducing the possibility of their suicide.

ERK3 Increases Snail Protein Stability by Inhibiting FBXO11-Mediated Snail Ubiquitination.

Snail is a key regulator of the epithelial-mesenchymal transition (EMT), the key step in the tumorigenesis and metastasis of tumors. Although induction of Snail transcription precedes the induction of EMT, the post-translational regulation of Snail is also important in determining Snail protein levels, stability, and its ability to induce EMT. Several kinases are known to enhance the stability of the Snail protein by preventing its ubiquitination; however, the precise molecular mechanisms by which these kinases prevent Snail ubiquitination remain unclear. Here, we identified ERK3 as a novel kinase that interacts with Snail and enhances its protein stability. Although ERK3 could not directly phosphorylate Snail, Erk3 increased Snail protein stability by inhibiting the binding of FBXO11, an E3 ubiquitin ligase that can induce Snail ubiquitination and degradation, to Snail. Importantly, functional studies and analysis of clinical samples indicated the crucial role of ERK3 in the regulation of Snail protein stability in pancreatic cancer. Therefore, we conclude that ERK3 is a key regulator for enhancing Snail protein stability in pancreatic cancer cells by inhibiting the interaction between Snail and FBXO11.