Cytoplasmic Polyadenylation Element Research Articles

CPEB4-Promoted Paclitaxel Resistance in Ovarian Cancer In Vitro Relies on Translational Regulation of CSAG2.

Background: Drug resistance is a major obstacle in chemotherapy for ovarian cancer, wherein the up regulation of drug-resistant genes plays an important role. The cytoplasmic polyadenylation element binding protein 4 (CPEB4) is an RNA binding protein that controls mRNA cytoplasmic polyadenylation and translation. Methods: The expression of CPEB4 in paclitaxel-resistant ovarian cancer cell lines and recurrent ovarian tumors relative to counterparts was determined by qRT-PCR, Western blotting and immunohistochemistry. The response to paclitaxel treatment was evaluated by cellular viability test and colony formation assay. RNA immunoprecipitation and poly(A) tail test were applied to examine the levels of RNA binding and cytoplasmic polyadenylation. Results: CPEB4 is elevated in paclitaxel-resistant ovarian cancer cells and recurrent ovarian tumors treated with paclitaxel-based chemotherapy. In addition, CPEB4 overexpression promotes paclitaxel resistance in ovarian cancer cells in vitro, and vice versa, CPEB4 knockdown restores paclitaxel sensitivity, indicating that CPEB4 confers paclitaxel resistance in ovarian cancer cells. Mechanistically, CPEB4 binds with the taxol (paclitaxel)-resistance-associated gene-3 (TRAG-3/CSAG2) mRNAs and induces its expression at a translational level. Moreover, CSAG2 expression is upregulated in paclitaxel-resistant ovarian carcinoma and cancer cell lines, and more importantly, siRNA-mediated CSAG2 knockdown overtly attenuates CPEB4-mediated paclitaxel resistance. Conclusion: This study suggests that the drug-resistant protein CSAG2 is translationally induced by CPEB4, which underlies CPEB4-promoted paclitaxel resistance in ovarian cancer in vitro. Thus, interfering CPEB4/CSAG2 axis might be of benefit to overcome paclitaxel-resistant ovarian cancer.

Gynura segetum induces hepatic sinusoidal obstruction syndrome in mice by impairing autophagy.

ABSTRACTPurpose:To investigate the underlying mechanism of hepatic sinusoidal obstruction syndrome (HSOS) induced by Gynura segetum by measuring autophagy in mouse models.Methods:The model group was administered G. segetum (30 g/kg/d) by gavage, while the normal control group was administered an equal volume of saline daily for five weeks. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), hepatic histopathological examinations, and Masson staining were performed to evaluate liver injury. Liver intercellular adhesion molecule-1 (ICAM-1) and P-selectin were evaluated by immunohistochemistry. Hepatocellular apoptosis was assessed using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Protein expression levels of autophagy markers were measured using Western blot analysis.Results: Gynura segetum was found to significantly induce liver injury compared with control mice, as evidenced by the increase of serum transaminases, a decrease in triglyceride levels, and histopathological changes in mice. Gynura segetum remarkably induced hepatocellular apoptosis and upregulated the expressions of ICAM-1 and P-selectin and also downregulated the protein expression levels of LC3, Atg12 and cytoplasmic polyadenylation element binding protein.Conclusions:Our results suggested that G. segetum induced liver injury with HSOS, and it was partly due to its ability to impair the autophagy pathway.

AUF1, an mRNA decay factor, has a discordant role in Cpeb1 expression

Cytoplasmic polyadenylation element binding protein 1 (CPEB1) regulates polyadenylation and subsequent translation of CPE-containing mRNAs involved in various physiological and pathological phenomena. Although the significance of CPEB1-mediated translational regulation has recently been reported, the detailed regulatory mechanism of Cpeb1 expression remains unclear. To elucidate the post-transcriptional regulatory mechanisms of Cpeb1 expression, we constructed reporter plasmids containing various deletions or mutations in the Cpeb1 mRNA 3′ untranslated region (3′UTR). We investigated their expression levels in Neuro2a neuroblastoma cells. We found that Cpeb1 expression is regulated through an AU-rich element in its 3′UTR. Furthermore, the mRNA decay factor AU-rich binding factor 1 (AUF1) regulates Cpeb1 expression, and knockdown of AUF1 upregulates Cpeb1 mRNA expression but results in a decrease in CPEB1 protein levels. These findings indicate that AUF1 has a discordant role in the expression of Cpeb1.

Positive Feedback Stimulation of Ccnb1 and Mos mRNA Translation by MAPK Cascade During Mouse Oocyte Maturation.

In mammalian species, both the maturation promoting factor (MPF) and the mitogen-activated protein kinase (MAPK) cascade play critical roles in modulating oocyte meiotic cell-cycle progression. MPF is a critical heterodimer composed of CDK1 and cyclin B1. Activation of MPF and ERK1/2 requires the activation of maternal Ccnb1 and Mos mRNAs translation, respectively. The phosphorylation and degradation of CPEB1 that triggered by ERK1/2 is a principal mechanism of activating maternal mRNA translation. However, the interplay of these two key kinases in mediating mammalian translational activation of cytoplasmic mRNAs during oocyte maturation is unclear. We prove evidence that the translational activation of Ccnb1 transcripts containing a long 3′-UTR during meiotic resumption works in an ERK1/2-dependent way. A low level of ERK1/2 activation was detected prior to meiotic resumption. Precocious activation of MAPK signaling in germinal vesicle stage oocytes promotes the translation of Ccnb1 mRNA and meiotic maturation. Inhibition or precocious activation of CDK1 activity has an appreciable effect on the translation of Ccnb1 mRNA, suggesting that both kinases are required for Ccnb1 mRNA translational activation. CDK1 triggers phosphorylation, but not degradation, of CPEB1 in oocytes; the degradation of CPEB1 was only triggered by ERK1/2. Moreover, the translational activation of Mos mRNA is regulated by ERK1/2 and cytoplasmic polyadenylation elements too. Taken together, the cooperation and positive feedback activation of ERK1/2 and CDK1 lead to the fine-tuning of mRNA translation and cell-cycle progression during mouse oocyte maturation.

CPEB1 orchestrates a fine-tuning of miR-145-5p tumor-suppressive activity on TWIST1 translation in prostate cancer cells.

TWIST1 is a basic helix-loop-helix transcription factor, and one of the master Epithelial-to-Mesenchymal Transition (EMT) regulators. We show that tumor suppressor miR-145-5p controls TWIST1 expression in an immortalized prostate epithelial cell line and in a tumorigenic prostate cancer-derived cell line. Indeed, shRNA-mediated miR-145-5p silencing enhanced TWIST1 expression and induced EMT-associated malignant properties in these cells. However, we discovered that the translational inhibitory effect of miR-145-5p on TWIST1 is lost in 22Rv1, another prostate cancer cell line that intrinsically expresses high levels of the CPEB1 cytoplasmic polyadenylation element binding protein. This translational regulator typically reduces TWIST1 translation efficiency by shortening the TWIST1 mRNA polyA tail. However, our results indicate that the presence of CPEB1 also interferes with the binding of miR-145-5p to the TWIST1 mRNA 3′UTR. Mechanistically, CPEB1 binding to its first cognate site either directly hampers the access to the miR-145-5p response element or redirects the cleavage/polyadenylation machinery to an intermediate polyadenylation site, resulting in the elimination of the miR-145-5p binding site. Taken together, our data support the notion that the tumor suppressive activity of miR-145-5p on TWIST1 translation, consequently on EMT, self-renewal, and migration, depends on the CPEB1 expression status of the cancer cell. A preliminary prospective study using clinical samples suggests that reconsidering the relative status of miR-145-5p/TWIST1 and CPEB1 in the tumors of prostate cancer patients may bear prognostic value.

Linc00968 inhibits the tumorigenesis and metastasis of lung adenocarcinoma via serving as a ceRNA against miR-9-5p and increasing CPEB3.

Increasing evidence confirms that long noncoding RNAs (lncRNAs) exert vital functions in multiple biological process among malignant cancers. In the current study, we uncovered that linc00968 was downregulated in lung adenocarcinoma (LUAD). Furthermore, the low level of linc00968 was correlated with worse prognosis in patients with LUAD. Upregulation of linc00968 restrained the growth and metastatic phenotypes of LUAD cell in vitro and in vivo. Using bioinformation methods and luciferase reporter assay, we identified that linc00968 acted as a competing endogenous RNA (ceRNA) via sponging miR-9-5p to modulate the level of Cytoplasmic Polyadenylation Element Binding Protein 3 (CPEB3) in LUAD. In addition, LUAD cell migration, colony formation and epithelial-mesenchymal transition (EMT) process were suppressed by linc00968 while these aggressive traits were reversed by miR-142-5p or CPEB3 silencing. Altogether, our work disclosed that linc00968 played a critical role in LUAD and linc00968/miR-9-5p/CPEB3 regulatory axis might be a potential treatment target in LUAD.

CPEB3 functions as a tumor suppressor in colorectal cancer via JAK/STAT signaling.

As RNA-binding proteins, cytoplasmic polyadenylation element binding proteins (CPEBs) have drawn increasing attention for their function of controlling gene expression related to malignant transformation via post-transcriptional regulation. However, the contribution of CPEB3 to malignant development in cancers is poorly understood. In this study, we explored the clinical, biological, and mechanical role of CPEB3 in colorectal cancer progression. We showed that colorectal cancer tissues exhibited dampened CPEB3 expression which was closely associated with poor prognosis in patients with colorectal cancer (47 vs. 62 months, P = 0.035, n=99). Down-regulation CPEB3 promoted proliferation, migration, and invasion in colorectal cancer cells and vice versa. Mechanistically, CPEB3 performed as an RNA binding protein binding to 3ʹUTR of JAK1 mRNA to inhibit JAK/STAT pathways in colorectal cancer cells. Knockdown of CPEB3 induced active JAK-STAT signaling, thereby triggering the proliferation and metastasis capacity of colorectal cancer cells. These results suggest that CPEB3 functions as a tumor suppressor in colorectal cancer through its post-transcriptional regulation of JAK/STAT signaling. Implications: This study identified a novel role of the RNA binding protein CPEB3 in inhibiting cell proliferation and migration as well as the underlining mechanisms in colorectal cancer cells.

Regulation of microRNA-221, -222, -21 and -27 in articular cartilage subjected to abnormal compressive forces.

Key points microRNAs (miRs) are small non‐coding molecules that regulate post‐transcriptional target gene expression.miRs are involved in regulating cellular activities in response to mechanical loading in all physiological systems, although it is largely unknown whether this response differs with increasing magnitudes of load.miR‐221, miR‐222, miR‐21‐5p and miR‐27a‐5p were significantly increased in ex vivo cartilage explants subjected to increasing load magnitude and in in vivo joint cartilage exposed to abnormal loading. TIMP3 and CPEB3 are putative miR targets in chondrocytesIdentification of mechanically regulated miRs that have potential to impact on tissue homeostasis provides a mechanism by which load‐induced tissue behaviour is regulated, in both health and pathology, in all physiological systems. MicroRNAs (miRs) are small non‐coding molecules that regulate post‐transcriptional target gene expression and are involved in mechano‐regulation of cellular activities in all physiological systems. It is unknown whether such epigenetic mechanisms are regulated in response to increasing magnitudes of load. The present study investigated mechano‐regulation of miRs in articular cartilage subjected to ‘physiological’ and ‘non‐physiological’ compressive loads in vitro as a model system and validated findings in an in vivo model of abnormal joint loading. Bovine full‐depth articular cartilage explants were loaded to 2.5 MPa (physiological) or 7 MPa (non‐physiological) (1 Hz, 15 min) and mechanically‐regulated miRs identified using next generation sequencing and verified using a quantitative PCR. Downstream targets were verified using miR‐specific mimics or inhibitors in conjunction with 3′‐UTR luciferase activity assays. A subset of miRs were mechanically‐regulated in ex vivo cartilage explants and in vivo joint cartilage. miR‐221, miR‐222, miR‐21‐5p and miR‐27a‐5p were increased and miR‐483 levels decreased with increasing load magnitude. Tissue inhibitor of metalloproteinase 3 (TIMP3) and cytoplasmic polyadenylation element binding protein 3 (CPEB3) were identified as putative downstream targets. Our data confirm miR‐221 and ‐222 mechano‐regulation and demonstrates novel mechano‐regulation of miR‐21‐5p and miR‐27a‐5p in ex vivo and in vivo cartilage loading models. TIMP3 and CPEB3 are putative miR targets in chondrocytes. Identification of specific miRs that are regulated by increasing load magnitude, as well as their potential to impact on tissue homeostasis, has direct relevance to other mechano‐sensitive physiological systems and provides a mechanism by which load‐induced tissue behaviour is regulated, in both health and pathology.

MSC-AS1 knockdown inhibits cell growth and temozolomide resistance by regulating miR-373-3p/CPEB4 axis in glioma through PI3K/Akt pathway

Long non-coding RNAs (lncRNAs) have been widely reported to regulate the development and chemoresistance of a variety of tumors. Temozolomide (TMZ) is a first-line chemotherapy for treatment of glioma. However, the effect and the regulatory mechanism of lncRNA MSC-AS1 (MSC-AS1) in TMZ-resistant glioma remain unrevealed. Levels of MSC-AS1, microRNA-373-3p (miR-373-3p), and cytoplasmic polyadenylation element binding protein 4 (CPEB4) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). All protein expression was detected by western blot. Cell viability and the half maximal inhibitory concentration (IC50) value of TMZ was assessed by cell counting kit-8 (CCK-8) assay. Cell cloning ability and apoptosis were examined by colony formation and flow cytometry assays, respectively. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were performed to verify the correlation between miR-373-3p and MSC-AS1 or CPEB4. The xenograft models were established to determine the effect of MSC-AS1 in vivo. MSC-AS1 was up-regulated in TMZ-resistant glioma tissues and cells, and glioma patients with high MSC-AS1 expression tend to have lower overall survival rate. MSC-AS1 suppression reduced the IC50 value of TMZ and proliferation, promoted apoptosis and TMZ sensitivity, and affected PI3K/Akt pathway in TMZ-resistant glioma cells. MSC-AS1 acted as miR-373-3p sponge, and miR-373-3p directly targeted CPEB4. Silencing miR-373-3p reversed the promoting effect of MSC-AS1 or CPEB4 knockdown on TMZ sensitivity. Furthermore, MSC-AS1 knockdown inhibited TMZ-resistant glioma growth in vivo by regulating miR-373-3p/CPEB4 axis through PI3K/Akt pathway. Collectively, MSC-AS1 knockdown suppressed cell growth and the chemoresistance of glioma cells to TMZ by regulating miR-373-3p/CPEB4 axis in vitro and in vivo through activating PI3K/Akt pathway.

Identification of genes involved in inbreeding depression of reproduction in Langshan chickens.

ObjectiveInbreeding depression of reproduction is a major concern in the conservation of native chicken genetic resources. Here, based on the successful development of strongly inbred (Sinb) and weakly inbred (Winb) Langshan chickens, we aimed to evaluate inbreeding effects on reproductive traits and identify candidate genes involved in inbreeding depression of reproduction in Langshan chickens.MethodsA two-sample t-test was performed to estimate the differences in phenotypic values of reproductive traits between Sinb and Winb chicken groups. Three healthy chickens with reproductive trait values around the group mean values were selected from each of the groups. Differences in ovarian and hypothalamus transcriptomes between the two groups of chickens were analyzed by RNA sequencing (RNA-Seq).ResultsThe Sinb chicken group showed an obvious inbreeding depression in reproduction, especially for traits of age at the first egg and egg number at 300 days (p<0.01). Furthermore, 68 and 618 differentially expressed genes (DEGs) were obtained in the hypothalamus and ovary between the two chicken groups, respectively. In the hypothalamus, DEGs were mainly enriched in the pathways related to vitamin metabolism, signal transduction and development of the reproductive system, such as the riboflavin metabolism, Wnt signaling pathway, extracellular matrix-receptor interaction and focal adhesion pathways, including stimulated by retinoic acid 6, serpin family F member 1, secreted frizzled related protein 2, Wnt family member 6, and frizzled class receptor 4 genes. In the ovary, DEGs were significantly enriched in pathways associated with basic metabolism, including amino acid metabolism, oxidative phosphorylation, and glycosaminoglycan degradation. A series of key DEGs involved in folate biosynthesis (gamma-glutamyl hydrolase, guanosine triphosphate cyclohydrolase 1), oocyte meiosis and ovarian function (cytoplasmic polyadenylation element binding protein 1, structural maintenance of chromosomes 1B, and speedy/RINGO cell cycle regulator family member A), spermatogenesis and male fertility (prostaglandin D2 synthase 21 kDa), Mov10 RISC complex RNA helicase like 1, and deuterosome assembly protein 1) were identified, and these may play important roles in inbreeding depression in reproduction.ConclusionThe results improve our understanding of the regulatory mechanisms underlying inbreeding depression in chicken reproduction and provide a theoretical basis for the conservation of species resources.

CircTTBK2 Contributes to the Progression of Glioma Through Regulating miR-145-5p/CPEB4 Axis.

BackgroundCurrently, circular RNAs (circRNAs) have been demonstrated to play vital roles in malignant tumors, including glioma. Nevertheless, the functions of circTTBK2 in glioma are largely unclear.Materials and MethodsQuantitative real-time polymerase chain reaction (qRT-PCR) was applied for the expression levels of circTTBK2, TTBK2 mRNA, miR-145-5p and cytoplasmic polyadenylation element binding protein 4 (CPEB4) mRNA. Actinomycin D and RNase R digestion assays were utilized for the characteristics of circTTBK2. 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay, flow cytometry analysis and transwell assay were conducted for cell proliferation, apoptosis and metastasis, respectively. The glycolysis level was estimated with specific kits. Western blot assay was adopted for the protein levels of hexokinase2 (HK2) and CPEB4. The targeting relationship between miR-145-5p and circTTBK2 or CPEB4 was verified by Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Murine xenograft assay was used for the role of circTTBK2 in tumorigenesis in vivo.ResultsCircTTBK2 was upregulated in glioma tissues and cells, and its level was associated with poor survival of glioma patients. CircTTBK2 knockdown suppressed glioma cell proliferation, migration, invasion and glycolysis and accelerated apoptosis in vitro and hampered tumor growth in vivo. CircTTBK2 functioned as a sponge of miR-145-5p, and miR-145-5p inhibition restored the effects of circTTBK2 knockdown on the malignant behaviors of glioma cells. Moreover, CPEB4 was the direct target gene of miR-145-5p, and miR-145-5p inhibition facilitated glioma cell progression by targeting CPEB4.ConclusionCircTTBK2 functioned as a tumor promoter in glioma by modulating miR-145-5p/CPEB4 axis, which might offer a new sight for glioma therapy.

CPEB3 inhibits epithelial-mesenchymal transition by disrupting the crosstalk between colorectal cancer cells and tumor-associated macrophages via IL-6R/STAT3 signaling

BackgroundCrosstalk between cancer cells and tumor-associated macrophages (TAMs) mediates tumor progression in colorectal cancer (CRC). Cytoplasmic polyadenylation element binding protein 3 (CPEB3) has been shown to exhibit tumor-suppressive role in CRC.MethodsThe expression of CPEB3, CD68, CD86 and CD163 was determined in CRC tissues. SW480 or HCT116 cells overexpressing CPEB3 and LoVo or RKO cells with CPEB3 knockdown were constructed. Stably transfected CRC cells were co-cultured with THP-1 macrophages to determine the malignant phenotype of CRC cells, macrophage polarization, and secretory signals. The inhibition of CPEB3 on tumor progression and M2-like TAM polarization was confirmed in nude mice.ResultsDecreased CPEB3 expression in CRC was associated with fewer CD86+ TAMs and more CD163+ TAMs. CPEB3 knockdown in CRC cells increased the number of CD163+ TAMs and the expression of IL1RA, IL-6, IL-4 and IL-10 in TAM supernatants. TAMs enhanced CRC cell proliferation and invasion via IL-6, and then activated the IL-6R/STAT3 pathway in CRC cells. However, CPEB3 reduced the IL-6R protein levels by directly binding to IL-6R mRNA, leading to decreased phosphorylated-STAT3 expression in CRC cells. CCL2 was significantly increased in CPEB3 knockdown cells, while CCL2 antibody treatment rescued the effect of CPEB3 knockdown in promoting CD163+ TAM polarization. Eventually, we confirmed that CPEB3 inhibits tumor progression and M2-like TAM polarization in vivo.ConclusionsCPEB3 is involved in the crosstalk between CRC cells and TAMs by targeting IL-6R/STAT3 signaling.

Cytoplasmic Polyadenylation Element Binding Proteins CPEB1 and CPEB3 Regulate the Translation of FosB and Are Required for Maintaining Addiction-Like Behaviors Induced by Cocaine.

A recurrent and devastating feature of addiction to a drug of abuse is its persistence, which is mediated by maladaptive long-term memories of the highly pleasurable experience initially associated with the consumption of the drug. We have recently found that members of the CPEB family of proteins (Cytoplasmic Polyadenylation Element-Binding Proteins) are involved in the maintenance of spatial memory. However, their possible role in the maintenance of memories that sustain addictive behavior has yet to be explored. Little is known about any of the mechanisms for maintaining memories for addictive behavior. To address the mechanisms whereby addictive behavior is maintained over time, we utilized a conditional transgenic mouse model expressing a dominant-negative version of CPEB1 that abolishes the activity in the forebrain of two of the four CPEB isoforms (CPEB1 and CPEB3). We found that, following cocaine administration, these dominant-negative (DN) CPEB mice showed a significant decrease, when compared to wild type (WT) mice, in both locomotor sensitizations and conditioned place preference (CPP), two indices of addictive behavior. Supporting these behavioral results, we also found a difference between WT and DN-CPEB1-3 mice in the cocaine-induced synaptic depression in the core of the Nucleus Accumbens (NAc). Finally, we found that (1) CPEB is reduced in transgenic mice following cocaine injections and that (2) FosB, known for its contribution to establishing the addictive phenotype, when its expression in the striatum is increased by drug administration, is a novel target of CPEBs molecules. Thus, our study highlights how CPEB1 and CPEB3 act on target mRNAs to build the neuroadaptative implicit memory responses that lead to the development of the cocaine addictive phenotypes in mammals.

Polyadenylation of mRNA as a novel regulatory mechanism of gene expression in temporal lobe epilepsy.

Temporal lobe epilepsy is the most common and refractory form of epilepsy in adults. Gene expression within affected structures such as the hippocampus displays extensive dysregulation and is implicated as a central pathomechanism. Post-transcriptional mechanisms are increasingly recognized as determinants of the gene expression landscape, but key mechanisms remain unexplored. Here we show, for first time, that cytoplasmic mRNA polyadenylation, one of the post-transcriptional mechanisms regulating gene expression, undergoes widespread reorganization in temporal lobe epilepsy. In the hippocampus of mice subjected to status epilepticus and epilepsy, we report >25% of the transcriptome displays changes in their poly(A) tail length, with deadenylation disproportionately affecting genes previously associated with epilepsy. Suggesting cytoplasmic polyadenylation element binding proteins (CPEBs) being one of the main contributors to mRNA polyadenylation changes, transcripts targeted by CPEBs were particularly enriched among the gene pool undergoing poly(A) tail alterations during epilepsy. Transcripts bound by CPEB4 were over-represented among transcripts with poly(A) tail alterations and epilepsy-related genes and CPEB4 expression was found to be increased in mouse models of seizures and resected hippocampi from patients with drug-refractory temporal lobe epilepsy. Finally, supporting an adaptive function for CPEB4, deletion of Cpeb4 exacerbated seizure severity and neurodegeneration during status epilepticus and the development of epilepsy in mice. Together, these findings reveal an additional layer of gene expression regulation during epilepsy and point to novel targets for seizure control and disease-modification in epilepsy.

The RNA-binding protein Cpeb4 is a novel positive regulator of osteoclast differentiation

Cytoplasmic polyadenylation element binding (CPEB) proteins are RNA-binding proteins involved in translational regulation of the specific target mRNAs and control function of various organs including brain, liver and hematopoietic system. However, the role of CPEB proteins during osteoclast differentiation remains unclear. Here we show that Cpeb4 is required for RANKL-induced osteoclast differentiation in mouse macrophage-derived RAW264.7 cell line. Cpeb4 mRNA and protein levels are upregulated at the late stage of osteoclast differentiation. Immunofluorescence analysis revealed that Cpeb4 is translocated from cytoplasm to nuclear bodies in response to RANKL stimulation. Inhibition of PI3K-Akt signaling or calcium-NFAT pathways using chemical inhibitors suppressed nuclear localization of Cpeb4. Loss-of-function analysis showed that shRNA-mediated Cpeb4 depletion strongly impaired TRAP-positive osteoclast formation and expression of key differentiation markers including Acp5, Ctsk, Nfatc1 and Dcstamp. These results suggest that Cpeb4 is a positive regulator in osteoclastogenesis downstream of RANKL signaling.

CPEB1 deletion is not a common explanation for premature ovarian insufficiency in a Chinese cohort

PurposePremature ovarian insufficiency (POI), which is characterized by early menopause before the age of 40 years, affects approximately 1–5% of women. Cytoplasmic polyadenylation element binding protein 1 (CPEB1) is a post-transcriptional regulatory protein that is highly expressed in germ cells and promotes oocytes maturation, and several studies have found microdeletions of chromosome 15q25.2, which contains the CPEB1 gene, in POI patients. However, the deleted region also includes other plausible genes, and thus the contribution of CPEB1 to POI is uncertain. The present study aimed to determine the relationship between CPEB1 deletion and POI in a Chinese cohort.Material and methodsQuantitative real-time polymerase chain reaction (qPCR) with primers for exon 4 and exon 11 of CPEB1 was performed to detect the CPEB1 deletion in 323 patients with POI and in 300 healthy controls. Subsequent qPCR with primers for each exon of CPEB1 was performed to precisely localize the deletion locus.ResultsOne patient with primary amenorrhea was found to carry a heterozygous deletion of exons 8–12 of the CPEB1 gene.ConclusionOur study is the first to search for CPEB1 deletions in POI patients using a simple qPCR method, and we show that CPEB1 deletion is not a common cause for POI in a Chinese cohort.

The Prion‐like Cytoplasmic Polyadenylation Element Binding (CPEB) Protein: Can Protein Aggregations in Long‐term Memory Formation inform Memory Loss in Amyloid Associated Neurodegenerative Disease?

Proteinaceous infectious particles or prions are harmful misfolded proteins characterized by a self‐perpetuating amyloidogenic state. These infectious agents target the nervous system and result in rare conditions including Creutzfeldt‐Jacobs disease and kuru, bovine spongiform encephalopathy and scrapie, which are fatal in humans, and cattle and sheep, respectively. Prions have two distinct states: monomeric and amyloidogenic aggregated. The monomeric state is non‐pathogenic while the aggregated state can recruit other monomers into the pathogenic aggregated form. Though not caused by prions, a number of neurodegenerative disorders including Alzheimer’s, Huntington’s, and Parkinson’s disease are associated with the accumulation of misfolded amyloid forming proteins in the brain. In concert with the discoveries involving prions and amyloid‐associated disease, a reductionist approach using the Aplysia sea slug was being developed to study modifications of simple reflexes and underlying neural circuits in an effort to uncover the molecular basis of short‐term and long‐term memory. Through these studies it has been demonstrated that long‐term memory is a function of changes that occur within the synapses and requires synthesis of new proteins in the synapse. More recently, a protein, cytoplasmic polyadenylation element‐binding (CPEB). In contrast to prions, prion‐like proteins are regulated and are functional in their aggregated state. The Blue Valley North 2019–2020 SMART (Students Modeling A Research Topic) Team, supported by the CBM at MSOE, modeled the Apylsia CPEB protein using JMol and 3D printing technology with the goal of exploring this protein’s unique properties and its role in memory formation. In its monomeric state CPEB is inhibited by the microRNA miR22. In contrast, when stimulated by serotonin, a neurotransmitter that induces long‐term synaptic facilitation, miR22 is downregulated, releasing CPEB from its inhibition, and allowing it to enter is active aggregate forming self‐sustaining state. In this state, CPEB activates dormant mRNA located in the axon terminals undergoing long‐term facilitation. Structurally, CPEB contains a N‐terminal region rich in glutamine and asparagine residues, and a C‐terminal RNA binding domain. Neuronal protein homologs with similar N‐terminal regions exist in yeast, mice, and humans as well. It is hypothesized that the N‐terminal region forms both a b‐sheet and an a‐helical coiled coil which facilitate aggregation and the formation of central axis from which the aggregate’s separate RNA binding domains protrude. These open and accessible RNA binding platforms expedite mRNA activation. In this manner CPEB can coordinate the translation of a population of mRNAs important in long‐term memory formation. Though counterintuitive we are hopeful that further structural analysis of the CPEB protein involved in memory formation will inform our understanding of amyloid aggregates associated with memory loss in neurodegenerative disease.

CPEB4 Increases Expression of PFKFB3 to Induce Glycolysis and Activate Mouse and Human Hepatic Stellate Cells, Promoting Liver Fibrosis

We investigated mechanisms of hepatic stellate cell (HSC) activation, which contributes toliver fibrogenesis. We aimed to determine whether activated HSCs increase glycolysis, which is regulated by6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3), and whether this pathway might serve as a therapeutic target. We performed studies with primary mouse HSCs, human LX2 HSCs, human cirrhotic liver tissues, rats and mice with liver fibrosis (due to bile duct ligation [BDL] or administration of carbon tetrachloride), and CPEB4-knockout mice. Glycolysis was inhibited in cells and mice by administration of a small molecule antagonist of PFKFB3 (3-[3-pyridinyl]-1-[4-pyridinyl]-2-propen-1-one [3PO]). Cells were transfected with small interfering RNAs that knock down PFKFB3 or CPEB4. Up-regulation of PFKFB3 protein and increased glycolysis were early and sustained events during HSC activation and accompanied by increased expression of markers of fibrogenesis; incubation of HSCs with 3PO or knockdown of PFKFB3 reduced their activation and proliferation. Mice with liver fibrosis after BDL had increased hepatic PFKFB3; injection of 3PO immediately after the surgery prevented HSC activation and reduced the severity of liver fibrosis compared with mice given vehicle. Levels of PFKFB3 protein were increased in fibrotic liver tissues from patients compared with non-fibrotic liver. Up-regulation of PFKFB3 in activated HSCs did not occur via increased transcription, but instead via binding of CPEB4 to cytoplasmic polyadenylation elements within the 3'-untranslated regions of PFKFB3 messenger RNA. Knockdown of CPEB4 in LX2 HSCs prevented PFKFB3 overexpression and cell activation. Livers from CPEB4-knockout had decreased PFKFB3 and fibrosis after BDL or administration of carbon tetrachloride compared with wild-type mice. Fibrotic liver tissues from patients and rodents (mice and rats) have increased levels of PFKFB3 and glycolysis, which are essential for activation of HSCs. Increased expression of PFKFB3 is mediated by binding of CPEB4 to its untranslated messenger RNA. Inhibition or knockdown of CPEB4 or PFKFB3 prevents HSC activation and fibrogenesis in livers of mice.

CPEB1 or CPEB4 knockdown suppresses the TAK1 and Smad signalings in THP-1 macrophage-like cells and dermal fibroblasts

Post-burn hypertrophic scar (HTS) is a form of excessive dermal fibrosis characterized by cutaneous scarring, which is common in patients following burn injury. Moreover, at least 50% of HTS are accompanied by inflammation. Cytoplasmic polyadenylation element binding (CPEB) proteins are key mRNA-binding proteins that control the translation of several mRNAs. However, their potential roles in treating dermal fibrosis and scarring remain unknown. Therefore, in this study, we aimed to investigate the effects of small interfering RNA (siRNA)-mediated knockdown of CPEB1 or CPEB4 in human THP-1 macrophages and dermal fibroblasts treated with LPS and TGF-β1. We found significantly increased CPEB1 and CPEB4 mRNA and protein levels in LPS-treated THP-1 cells and TGF-β1–treated fibroblasts. CPEB1 and CPEB4 knockdowns suppressed LPS-activated TAK1 signaling cascades by reducing the levels of TNF-α and phosphorylated TAK1, p38, ERK, JNK, and NF-κB-p65 in THP-1 cells. CPEB1 and CPEB4 knockdowns also attenuated TGF-β1-activated Smad-dependent and -independent signaling cascades by reducing the levels of TAK1, p38, ERK, JNK, and phosphorylated Smad 2 and Smad 1/5/8 in fibroblasts. Furthermore, CPEB1 or CPEB4 knockdown markedly decreased the levels of fibrosis markers, including α-SMA, type I collagen, and fibronectin in fibroblasts. Our findings indicate that CPEB1 and CPEB4 are involved in the regulation of the TAK1 and Smad signalings in human macrophages and dermal fibroblasts. These activities may play a role in cutaneous scarring responses.

The cytoplasmic polyadenylation element binding protein (CPEB), Orb, is important for dendrite development and neuron fate specification in Drosophila melanogaster.

Cytoplasmic polyadenylation element binding proteins (CPEBs) are widely conserved proteins that regulate the length of poly(A) tails in the cytoplasm, regulate translation, and regulate mRNA transport. While CPEBs are best known for regulating maternal messages in oocytes, CPEBs also have roles in many other cell types including neurons. Here we extend our knowledge of the roles of CPEBs in neurons by showing that the Drosophila CPEB-encoding gene, orb, is required for proper dendrite development in larval sensory dendritic arborization neurons. Furthermore, we provide evidence that orb is important for neuron cell fate specification.