SOX9 is regulated by AURKA in response to Helicobacter pylori infection via EIF4E-mediated cap-dependent translation

Helicobacter pylori (H. pylori) infection is the main risk factor for gastric cancer. The SRY-Box Transcription Factor 9 (SOX9) serves as a marker of stomach stem cells. We detected strong associations between AURKA and SOX9 expression levels in gastric cancers. Utilizing in vitro and in vivo mouse models, we demonstrated that H. pylori infection induced elevated levels of both AURKA and SOX9 proteins. Notably, the SOX9 protein and transcription activity levels were dependent on AURKA expression. AURKA knockdown led to a reduction in the number and size of gastric gland organoids. Conditional knockout of AURKA in mice resulted in a decrease in SOX9 baseline level in AURKA-knockout gastric glands, accompanied by diminished SOX9 induction following H. pylori infection. We found an AURKA-dependent increase in EIF4E and cap-dependent translation with an AURKA-EIF4E-dependent increase in SOX9 polysomal RNA levels. Immunoprecipitation assays demonstrated binding of AURKA to EIF4E with a decrease in EIF4E ubiquitination. Immunohistochemistry analysis on tissue arrays revealed moderate to strong immunostaining of AURKA and SOX9 with a significant correlation in gastric cancer tissues. These findings elucidate the mechanistic role of AURKA in regulating SOX9 levels via cap-dependent translation in response to H. pylori infection in gastric tumorigenesis.

Targeting protein folding in N-Myc-driven medulloblastoma

Selective targeting of N-Myc-driven Sonic hedgehog (SHH) medulloblastoma has been a challenge for many years and, despite decades of research, few targeted therapy opportunities exist. Recently, Kuzuoglu-Ozturk et al. characterized the translatome of N-Myc-driven medulloblastoma as a promising therapeutic target. The study showed that N-Myc controls a subset of members of the protein folding machinery that could be inhibited pharmacologically and validated a subset of Hsp70 functions as required for medulloblastoma progression in vitro and in vivo.

Predictive value and regulatory mechanism of serum miR-499a-5p on myocardial dysfunction in sepsis

Background

This study sought to investigate the predictive value and regulatory mechanism of serum miR-499a-5p in sepsis-induced myocardial dysfunction (SIMD).

Methods

A total of 60 patients with sepsis and 60 healthy volunteers were enrolled in this study. The serum levels of miRNAs (miR-451, miR-378 and miR-499a-5p) were detected. Receiver operating characteristic curve and logistic regression analysis were used to evaluate the diagnostic and prognostic value of miR-499a-5p in SIMD patients. AC16 cells were used to establish SIMD model in vitro using lipopolysaccharide (LPS). An analysis was conducted for miR-499a-5p expression, cell viability, and the concentration of creatine kinase-MB isoform (CK-MB), brain natriuretic peptide (BNP), superoxide dismutase (SOD) and cytochrome C oxidase IV (COX IV). The downstream target of miR-499a-5p was verified.

Results

Our results revealed a poor expression of miR-499a-5p in the serum of SIMD patients, while no significant difference was evident for miR-451 and miR-378. The level of miR-499a-5p in the survival group was higher than the non-survival group. miR-499a-5p elicited good diagnostic and prognostic value for SIMD. Our findings revealed that miR-499a-5p was decreased significantly in LPS-treated cardiomyocytes. After overexpression of miR-499a-5p, the cell viability increased, and the concentrations of CK-MB and BNP were decreased, while the concentrations of SOD and COX IV were increased. EIF4E was validated as the target of miR-499a-5p. After overexpression of EIF4E, the cell viability was decreased and the concentrations of CK-MB and BNP were increased while the concentrations of SOD and COX IV were decreased.

Conclusion

The level of miR-499a-5p is weak in SIMD patients. miR-499a-5p has a good diagnostic and prognostic value for SIMD by inhibiting EIF4E transcription.

Evidence of viral genome linked protein of banana bract mosaic virus interaction with translational eukaryotic initiation factor 4E of plantain cv. Nendran based on yeast two hybrid system study

Banana bract mosaic virus (BBrMV), belongs to the genus Potyvirus and it is an important viral pathogen of bananas and plantains. The eukaryotic translation initiation factor, eIF4E, and its isoform play key roles during the virus infection in plants, particularly Potyvirus. The present study was undertaken to determine the role of BBrMV-viral protein genome-linked (VPg) in virus infectivity by analyzing the interaction with the eukaryotic translation initiation factor eIF4E through yeast two-hybrid system. The results suggest that plantain cv. Nendran eIF4E plays an essential role in the initiation of the translation of capped mRNAs and its association with VPg would point to a role of the viral protein in the translation of the virus and may potentially contribute to BBrMV resistance.

MTA2 promotes the metastasis of esophageal squamous cell carcinoma via EIF4E-Twist feedback loop

Metastasis‐associated protein 2 (MTA2) is frequently amplified in many types of cancers; however, the role and underlying molecular mechanism of MTA2 in esophageal squamous cell carcinoma (ESCC) remain unknown. Here, we reported that MTA2 is highly expressed in ESCC tissue and cells, and is closely related to the malignant characteristics and poor prognosis of patients with ESCC. Through in vitro and in vivo experiments, we demonstrated that MTA2 significantly promoted ESCC growth, metastasis, and epithelial‐mesenchymal transition (EMT) progression. This integrative analysis combined with expression microarray showed that MTA2 could interact with eukaryotic initiation factor 4E (EIF4E), which positively regulates the expression of Twist, known as a master regulator of EMT. Moreover, the results of chromatin immunoprecipitation revealed that MTA2 was recruited to the E‐cadherin promoter by Twist, which reduced the acetylation level of the promoter region and thus inhibited expression of E‐cadherin, and subsequently promoted the aggressive progression of ESCC. Collectively, our study provided novel evidence that MTA2 plays an aggressive role in ESCC metastasis by a novel EIF4E‐Twist positive feedback loop, which may provide a potential therapeutic target for the management of ESCC.

Leptin Receptor Signaling Regulates Protein Synthesis Pathways and Neuronal Differentiation in Pluripotent Stem Cells

The role of leptin receptor (OB-R) signaling in linking pluripotency with growth and development and the consequences of dysfunctional leptin signaling on progression of metabolic disease is poorly understood. Using a global unbiased proteomics approach we report that embryonic fibroblasts (MEFs) carrying the db/db mutation exhibit metabolic abnormalities, while their reprogrammed induced pluripotent stem cells (iPSCs) show altered expression of proteins involved in embryonic development. An upregulation in expression of eukaryotic translation initiation factor 4e (Eif4e) and Stat3 binding to the Eif4e promoter was supported by enhanced protein synthesis in mutant iPSCs. Directed differentiation of db/db iPSCs toward the neuronal lineage showed defects. Gene editing to correct the point mutation in db/db iPSCs using CRISPR-Cas9, restored expression of neuronal markers and protein synthesis while reversing the metabolic defects. These data imply a direct role for OB-R in regulating metabolism in embryonic fibroblasts and key developmental pathways in iPSCs.

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Pluripotency markers are decreased in db/db iPSCs (lacking functional OB-R)

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Mouse db/db iPSCs exhibit higher protein synthesis mediated by the Stat3/Eif4e axis

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OB-R signaling regulates neuronal development markers—NOGGIN, NESTIN, GFAP

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CRISPR correction reverses defects in db/db iPSCs

Knockdown of lncRNA MCM3AP-AS1 Attenuates Chemoresistance of Burkitt Lymphoma to Doxorubicin Treatment via Targeting the miR-15a/EIF4E Axis

Purpose

The long-noncoding RNA MCM3AP-AS1 has been shown to participate in the tumorigenesis and growth of several types of cancer, but little is known about the role of MCM3AP-AS1 in the chemoresistance of lymphoma.

Methods

A series of patients with Burkitt lymphoma were enrolled for clinical analysis. Daudi and Namalwa cells were used for further experiments. CCK-8 and apoptosis assays were used to assess the response to doxorubicin. Mitochondrial membrane potential assays and high-resolution respirometry were used to assess mitochondrial function. Western blotting was used to detect the expression of certain molecules. Luciferase assays and microRNA transfection were used to clarify the regulatory mechanisms of MCM3AP-AS1. An in vivo model using BALB/c nude mice was utilized to investigate the effects of MCM3AP-AS1 on cell proliferation and tumor growth.

Results

The expression level of MCM3AP-AS1 was increased in tumors compared with normal lymph nodes, which indicated poor prognosis in patients with Burkitt lymphoma. Moreover, compared with siNC transfection, MCM3AP-AS1 knockdown decreased cell viability and increased apoptosis rates upon doxorubicin treatment compared with siNC. Further studies indicated that upregulation of several antiapoptotic factors, downstream of EIF4E, was partially responsible for MCM3AP-AS1-induced chemoresistance. Moreover, miR-15a functioned as a link between MCM3AP-AS1 and EIF4E, and was sponged by MCM3AP-AS1. Finally, we showed that the MCM3AP-AS1/miR-15a/EIF4E axis regulated the chemoresistance of lymphoma cells in vitro and in vivo.

Conclusion

MCM3AP-AS1/miR-15a/EIF4E axis plays a role in the chemoresistance of Burkitt lymphoma, and it might become a promising target for lymphoma therapeutics.

Ophiopogonin D inhibits proliferation, migration, and invasion of hepatocellular carcinoma cells by regulating miR-519d-3p/EIF4E expression

BACKGROUND

Ophiopogonin D (OPD) is an important monomer component in Chinese traditional medicine. Ophiopogon extract has anti-cancer effects, but it is unknown whether it has anti-liver cancer effects. We hypothesized that OPD could have anti-liver cancer activity by up-regulating the expression of miR-519d-3p and then down-regulating the expression of eukaryotic translation initiation factor 4E (EIF4E).

AIM

To investigate the effects of OPD on proliferation, migration, and invasion of hepatocellular carcinoma cells and the possible mechanism involved.

METHODS

HepG2 and MHCC97 cells were cultured for 48 h after treatment with different concentrations (2.5, 5, and 10 μmol/L) of OPD. Methylthiazoletrazolium (MTT) assay was used to detect cell proliferation, Transwell assay was used to detect cell migration and invasion, real-time quantitative PCR (RT-qPCR) was used to detect the levels of miR-519d-3p and EIF4E mRNA in HepG2 cells, and Western blot was used to detect the expression levels of CyclinD1, p21, matrix metalloproteinase (MMP)-2, MMP-9, and EIF4E proteins. Dual luciferase reporter gene assay was used to validate the relationship between miR-519d-3p and EIF4E. To obtain HepG2 or MHCC97 cells with miR-519d-3p overexpression or EIF4E knockdown, miR-519d-3p mimic or si-EIF4E was transfected into HepG2 or MHCC97 cells. Then, RT-qPCR was used to detect the level of miR-519d-3p expression in HepG2 or MHCC97 cells and Western blot was performed to detect the level of EIF4E protein to verify the transfection efficiency. MTT assay, Transwell assay, and Western blot were used to detect the effects of overexpression of miR-519d-3p or inhibition of EIF4E on cell proliferation, migration, and invasion as well as the expression of CyclinD1, p21, MMP-2, and MMP-9 proteins.

RESULTS

Compared with control cells, the rates of reduced growth of HepG2 cells in the OPD groups were significantly increased (P < 0.05), cell migration and invasion were significantly decreased (P < 0.05), the levels of CyclinD1, MMP-2, and MMP-9 proteins were significantly decreased (P < 0.05), p21 protein expression was significantly increased (P < 0.05), miR-519d-3p expression was significantly increased (P < 0.05), and the levels of EIF4E mRNA and protein were significantly decreased (P < 0.05). MiR-519d-3p negatively regulated EIF4E expression in HepG2 cells. Overexpression of miR-519d-3p or inhibition of EIF4E inhibited the proliferation, migration, and invasion of HepG2 cells. Inhibition of miR-519d-3p expression partially reversed the inhibitory effect of OPD on the proliferation, migration, and invasion of HepG2 cells.

CONCLUSION

OPD inhibits the proliferation, migration, and invasion of hepatoma cells possibly by regulating the expression of miR-519d-3p/EIF4E.

Targeting EIF4F complex in non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) accounts for about 85–90% of lung cancer cases, which represents the leading cause of cancer-related death in the world. The majority of lung cancer patients doesn't respond well to conventional chemo-/radio-therapeutic regimens and have a poor prognosis. The recent introduction of targeted therapy and immunotherapy gives new hopes to NSCLC patients, but their outcome/prognosis is far from satisfactory. The translation initiation EIF4F complex has been shown to play important roles in cancer progression, but its functional role and therapeutic effect in lung cancers especially NSCLC remain largely unknown. In this current review, we summarize recent findings regarding the role of EIF4F complex in NSCLC progression and targeted therapy potentials. We also discuss the unanswered questions and future directions in this field.

Significance of MNK1 in prognostic prediction and chemotherapy development of epithelial ovarian cancer

BACKGROUND

Ovarian cancer is the most lethal gynecologic malignancy worldwide with surgery as the only curative treatment. Long-term overall survival (OS) of ovarian cancer is far from satisfactory, even though significant improvement has been made in post-operative chemotherapy. One of the most important death cause is the chemoresistance due to consecutive chemotherapy. Therefore, understanding the molecular mechanisms involved in ovarian cancer development and identification of novel therapeutic targets are urgently required.

METHODS

Immunohistochemical (IHC) staining was used to explore the expression pattern of mitogen-activated protein kinase (MAPK)-interacting kinase 1 (MNK1) in tumor tissues from 138 epithelial ovarian cancer (EOC) patients. Clinicopathological data were subjected to Kaplan-Meier survival and Cox multivariate analyses to evaluate the prognostic value of MNK1 in EOC. Overexpression and silencing procedures were performed on OVCAR-5 cells to investigate the mechanisms of MNK1 in regulating EOC development. The anti-tumor effects of CGP57380, a specific MNK inhibitor, were examined by cell viability assay.

RESULTS

Higher MNK1 expression showed significant relationship with advanced FIGO stage and positive lymph node metastasis of EOC. Univariate and multivariate analyses revealed that MNK1 was an independent prognostic factor for OS of EOC patients. In vitro study demonstrated that MNK1 can promote cell proliferation through regulating the phosphorylation level of eukaryotic initiation factor 4E. In addition, inhibition of MNK1 by CGP57380 significantly down-regulated the OVCAR-5 cell viability.

CONCLUSION

High MNK1 expression in EOC tissues indicates poor clinical outcomes, and MNK1 can act as a potential target for novel chemotherapy development towards EOC.

HPV18 E7 induces the over-transcription of eIF4E gene in cervical cancer

OBJECTIVES

Eukaryotic translation initiation factor 4E (eIF4E) is overexpressed in cervical cancer (CC). However, the molecular mechanisms are unclear. This study aimed to investigate the molecular mechanism of eIF4E gene overexpression in CC.

MATERIALS AND METHODS

The human papillomavirus (HPV) type 18 E7 and eIF4E mRNAs were measured following knock down or overexpression of E7 gene by RT-PCR and real-time PCR. Cell counting kit-8 assay was used to determine the cell proliferation. Flow cytometry was used to analyze the cell cycle and apoptosis. Transwell system was employed to determine the cell migration.

RESULTS

Overexpression of E7 gene increased eIF4E mRNA level by 24.3% (P<0.01) in HPV negative C33A cells. Knock down of E7 decreased markedly eIF4E mRNA by 73% (P<0.01) in HPV18 positive HeLa cells. Under the state of high expression of E7, 1) up-regulation of eIF4E drastically promoted the cell proliferation, cell cycle and cell migration, and inhibited the cell apoptosis. 2) down-regulation of eIF4E significantly inhibited the cell proliferation, cell cycle and the ability of cell migration, and also promoted the apoptosis of cervical cancer cells.

CONCLUSION

HPV E7 induced eIF4E gene over transcription which might be a new marker for CC. The finding broadens the understanding of the CC carcinogenesis.

elegans regulates growth, embryogenesis, and germline sex-determination

eIF4E plays a conserved role in initiating protein synthesis, but with multiple eIF4E isoforms present in many organisms, these proteins also adopt specialized functions. Previous RNAi studies showed that ife-3, encoding the sole canonical eIF4E isoform of Caenorhabditis elegans, is essential for viability. Using ife-3 gene mutations, we show here that it is maternal ife-3 function that is essential for embryogenesis, but ife-3 null progeny of heterozygous animals are viable. We find that zygotic ife-3 function promotes body growth and regulates germline development in hermaphrodite worms. Specifically, the normal transition from spermatogenesis to oogenesis in the hermaphrodite germline fails in ife-3 mutants. This failure to switch is reversed by inhibiting expression of the key masculinizing gene, fem-3, suggesting ife-3 resembles a growing number of genes that promote the sperm/oocyte switch by acting genetically as upstream inhibitors of fem-3.

Cellular, molecular, and epigenetic mechanisms in non-associative conditioning: implications for pain and memory

Sensitization is a form of non-associative conditioning in which amplification of behavioral responses can occur following presentation of an aversive or noxious stimulus. Understanding the cellular and molecular underpinnings of sensitization has been an overarching theme spanning the field of learning and memory as well as that of pain research. In this review we examine how sensitization, both in the context of learning as well as pain processing, shares evolutionarily conserved behavioral, cellular/synaptic, and epigenetic mechanisms across phyla. First, we characterize the behavioral phenomenon of sensitization both in invertebrates and vertebrates. Particular emphasis is placed on long-term sensitization (LTS) of withdrawal reflexes in Aplysia following aversive stimulation or injury, although additional invertebrate models are also covered. In the context of vertebrates, sensitization of mammalian hyperarousal in a model of post-traumatic stress disorder (PTSD), as well as mammalian models of inflammatory and neuropathic pain is characterized. Second, we investigate the cellular and synaptic mechanisms underlying these behaviors. We focus our discussion on serotonin-mediated long-term facilitation (LTF) and axotomy-mediated long-term hyperexcitability (LTH) in reduced Aplysia systems, as well as mammalian spinal plasticity mechanisms of central sensitization. Third, we explore recent evidence implicating epigenetic mechanisms in learning- and pain-related sensitization. This review illustrates the fundamental and functional overlay of the learning and memory field with the pain field which argues for homologous persistent plasticity mechanisms in response to sensitizing stimuli or injury across phyla.