RESUMO
Circular RNAs (circRNAs) are upregulated during neurogenesis. Where and how circRNAs are localized and what roles they play during this process have remained elusive. Comparing the nuclear and cytoplasmic circRNAs between H9 cells and H9-derived forebrain (FB) neurons, we identify that a subset of adenosine (A)-rich circRNAs are restricted in H9 nuclei but exported to cytosols upon differentiation. Such a subcellular relocation of circRNAs is modulated by the poly(A)-binding protein PABPC1. In the H9 nucleus, newly produced (A)-rich circRNAs are bound by PABPC1 and trapped by the nuclear basket protein TPR to prevent their export. Modulating (A)-rich motifs in circRNAs alters their subcellular localization, and introducing (A)-rich circRNAs in H9 cytosols results in mRNA translation suppression. Moreover, decreased nuclear PABPC1 upon neuronal differentiation enables the export of (A)-rich circRNAs, including circRTN4(2,3), which is required for neurite outgrowth. These findings uncover subcellular localization features of circRNAs, linking their processing and function during neurogenesis.
Assuntos
Transporte Ativo do Núcleo Celular , Adenosina , Núcleo Celular , Neurogênese , Neurônios , Proteína I de Ligação a Poli(A) , RNA Circular , RNA , RNA Circular/metabolismo , RNA Circular/genética , Neurônios/metabolismo , Adenosina/metabolismo , Núcleo Celular/metabolismo , Humanos , Proteína I de Ligação a Poli(A)/metabolismo , Proteína I de Ligação a Poli(A)/genética , Animais , RNA/metabolismo , RNA/genética , Linhagem Celular , Diferenciação Celular , Citoplasma/metabolismo , Prosencéfalo/metabolismoRESUMO
Helicobacter pylori (H. pylori) infection is the primary risk factor for the pathogenesis of gastric cancer (GC). N6-methyladenosine (m6A) plays pivotal roles in mRNA metabolism and hnRNPA2B1 as an m6A reader is shown to exert m6A-dependent mRNA stabilization in cancer. This study aims to explore the role of hnRNPA2B1 in H. pylori-associated GC and its novel molecular mechanism. Multiple datasets and tissue microarray are utilized for assessing hnRNPA2B1 expression in response to H. pylori infection and its clinical prognosis in patients with GC. The roles of hnRNPA2B1 are investigated through a variety of techniques including glucose metabolism analysis, m6A-epitranscriptomic microarray, Ribo-seq, polysome profiling, RIP-seq. In addition, hnRNPA2B1 interaction with poly(A) binding protein cytoplasmic 1 (PABPC1) is validated using mass spectrometry and co-IP. These results show that hnRNPA2B1 is upregulated in GC and correlated with poor prognosis. H. pylori infection induces hnRNPA2B1 upregulation through recruiting NF-κB to its promoter. Intriguingly, cytoplasm-anchored hnRNPA2B1 coordinated PABPC1 to stabilize its relationship with cap-binding eIF4F complex, which facilitated the translation of CIP2A, DLAT and GPX1 independent of m6A modification. In summary, hnRNPA2B1 facilitates the non-m6A translation of epigenetic mRNAs in GC progression by interacting with PABPC1-eIF4F complex and predicts poor prognosis for patients with GC.
Assuntos
Progressão da Doença , Infecções por Helicobacter , Helicobacter pylori , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B , Proteína I de Ligação a Poli(A) , Neoplasias Gástricas , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/microbiologia , Neoplasias Gástricas/patologia , Humanos , Helicobacter pylori/genética , Helicobacter pylori/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/genética , Infecções por Helicobacter/genética , Infecções por Helicobacter/metabolismo , Proteína I de Ligação a Poli(A)/metabolismo , Proteína I de Ligação a Poli(A)/genética , Camundongos , Animais , Prognóstico , Modelos Animais de Doenças , Masculino , Adenosina/análogos & derivados , Adenosina/metabolismo , Adenosina/genéticaRESUMO
Generally shortened 3' UTR due to alternative polyadenylation (APA) is widely observed in cancer, but its regulation mechanisms for cancer are not well characterized. Here, with profiling of APA in colorectal cancer tissues and poly(A) signal editing, we firstly identified that the shortened 3' UTR of CTNNIBP1 in colorectal cancer promotes cell proliferation and migration. We found that liquid-liquid phase separation (LLPS) of PABPN1 is reduced albeit with higher expression in cancer, and the reduction of LLPS leads to the shortened 3' UTR of CTNNBIP1 and promotes cell proliferation and migration. Notably, the splicing factor SNRPD2 upregulated in colorectal cancer, can interact with glutamic-proline (EP) domain of PABPN1, and then disrupt LLPS of PABPN1, which attenuates the repression effect of PABPN1 on the proximal poly(A) sites. Our results firstly reveal a new regulation mechanism of APA by disruption of LLPS of PABPN1, suggesting that regulation of APA by interfering LLPS of 3' end processing factor may have the potential as a new way for the treatment of cancer.
Assuntos
Regiões 3' não Traduzidas , Movimento Celular , Proliferação de Células , Neoplasias Colorretais , Proteína I de Ligação a Poli(A) , Poliadenilação , Humanos , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Proteína I de Ligação a Poli(A)/metabolismo , Proteína I de Ligação a Poli(A)/genética , Movimento Celular/genética , Regiões 3' não Traduzidas/genética , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Separação de FasesRESUMO
Background: Alzheimer's disease (AD) is the most prevalent neurological disorder worldwide, affecting approximately 24 million individuals. Despite more than a century of research on AD, its pathophysiology is still not fully understood. Objective: Recently, genetic studies of AD have focused on analyzing the general expression profile by employing high-throughput genomic techniques such as microarrays. Current research has leveraged bioinformatics advancements in genetic science to build upon previous efforts. Methods: Data from the GSE118553 dataset used in this investigation, and the analyses carried out using programs such as Limma and BioBase. Differentially expressed genes (DEGs) and differentially expressed microRNAs (DEmiRs) associated with AD identified in the studied areas of the brain. Target genes of the DEmiRs identified using the MultiMiR package. Gene ontology (GO) completed using the Enrichr website, and the protein-protein interaction (PPI) network for these genes drawn using STRING and Cytoscape software. Results: The findings introduced DEGs including CTNNB1, PAK2, MAP2K1, PNPLA6, IGF1R, FOXL2, DKK3, LAMA4, PABPN1, and GDPD5, and DEmiRs linked to AD (miR-106A, miR-1826, miR-1253, miR-10B, miR-18B, miR-101-2, miR-761, miR-199A1, miR-379 and miR-668), (miR-720, miR-218-2, miR-25, miR-602, miR-1226, miR-548K, miR-H1, miR-410, miR-548F2, miR-181A2), (miR-1470, miR-651, miR-544, miR-1826, miR-195, miR-610, miR-599, miR-323, miR-587 and miR-340), and (miR-1282, miR-1914, miR-642, miR-1323, miR-373, miR-323, miR-1322, miR-612, miR-606 and miR-758) in cerebellum, frontal cortex, temporal cortex, and entorhinal cortex, respectively. Conclusions: The majority of the genes and miRNAs identified by our findings may be employed as biomarkers for prediction, diagnosis, or therapy response monitoring.
Assuntos
Doença de Alzheimer , MicroRNAs , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , Redes Reguladoras de Genes/genética , Doença de Alzheimer/genética , Doença de Alzheimer/terapia , RNA Mensageiro/genética , Perfilação da Expressão Gênica/métodos , Biologia Computacional/métodos , Proteína I de Ligação a Poli(A)/genéticaRESUMO
Breast cancer is one of the major malignant tumors among women worldwide. Long noncoding RNAs (lncRNAs) have been documented as significant modulators in the development and progression of various cancers; however, the contribution of lncRNAs to breast cancer remains largely unknown. In this study, we found a novel lncRNA (NONHSAT137675) whose expression was significantly increased in the breast cancer tissues. We named the novel lncRNA as lncRNA PRBC (PABPC1-related lncRNA in breast cancer) and identified it as a key lncRNA associated with breast cancer progression and prognosis. Functional analysis displayed that lncRNA PRBC could promote autophagy and progression of breast cancer. Mechanistically, we verified that lncRNA PRBC physically interacted with PABPC1 through RIP assay, and PABPC1 overexpression could reverse the inhibiting effect of lncRNA PRBC knockdown on the malignant behaviors in breast cancer cells. Knockdown of lncRNA PRBC interfered the translocation of PABPC1 from nucleus to cytoplasm as indicated by western blot and IF assays. Significantly, the cytoplasmic location of PABPC1 was required for the interaction between PABPC1 and AGO2, which could be enhanced by lncRNA PRBC overexpression, leading to strengthened recruitment of mRNA to RNA-induced silencing complex (RISC) and thus reinforcing the inhibition efficiency of miRNAs. In general, lncRNA PRBC played a critical role in malignant progression of breast cancer by inducing the cytoplasmic translocation of PABPC1 to further regulate the function of downstream miRNAs. This study provides novel insight on the molecular mechanism of breast cancer progression, and lncRNA PRBC might be a promising therapeutic target and prognostic predictor for breast cancer.
Assuntos
Neoplasias da Mama , Proteína I de Ligação a Poli(A) , RNA Longo não Codificante , Feminino , Humanos , Autofagia/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , RNA Mensageiro/genética , Proteínas de Ligação a RNA/genéticaRESUMO
OBJECTIVE: Clinical and genetic heterogeneities make diagnosis of limb-girdle muscular dystrophy (LGMD) and other overlapping disorders of muscle weakness complicated and expensive. We aimed to develop a comprehensive next generation sequence-based multi-gene panel ("The Lantern Focused Neuromuscular Panel") to detect both sequence variants and copy number variants in one assay. METHODS: Patients with clinical diagnosis of LGMD or other overlapping muscular dystrophies in the United States were tested by PerkinElmer Genomics in 2018-2021 via "The Lantern Project," a sponsored diagnostic testing program. Sixty-six genes related to LGMD subtypes- and other myopathies were investigated. Main outcomes were diagnostic yield, gene-variant spectrum, and LGMD subtypes' prevalence. RESULTS: Molecular diagnosis was established in 19.6% (1266) of 6473 cases. Major genes contributing to LGMD were identified including CAPN3 (5.4%, 68), DYSF (4.0%, 51), GAA (3.7%, 47), ANO5 (3.6%, 45), and FKRP (2.7%, 34). Genes of other overlapping MD subtypes identified included PABPN1 (10.5%, 133), VCP (2.2%, 28), MYOT (1.2% 15), LDB3 (1.0%, 13), COL6A1 (1.5%, 19), FLNC (1.1%, 14), and DNAJB6 (0.8%, 10). Different sizes of copy number variants including single exon, multi-exon, and whole genes were identified in 7.5% (95) cases in genes including DMD, EMD, CAPN3, ANO5, SGCG, COL6A2, DOK7, and LAMA2. INTERPRETATION: "The Lantern Focused Neuromuscular Panel" enables identification of LGMD subtypes and other myopathies with overlapping clinical features. Prevalence of some MD subtypes was higher than previously reported. Widespread deployment of this comprehensive NGS panel has the potential to ensure early, accurate diagnosis as well as re-define MD epidemiology.
Assuntos
Doenças Musculares , Distrofia Muscular do Cíngulo dos Membros , Humanos , Estados Unidos , Variações do Número de Cópias de DNA/genética , Doenças Musculares/genética , Distrofia Muscular do Cíngulo dos Membros/diagnóstico , Distrofia Muscular do Cíngulo dos Membros/genética , Éxons , Proteínas do Tecido Nervoso/genética , Chaperonas Moleculares/genética , Proteínas de Choque Térmico HSP40/genética , Pentosiltransferases/genética , Anoctaminas/genética , Proteína I de Ligação a Poli(A)/genéticaRESUMO
Autophagy is an intracellular degradative process with an important role in cellular homeostasis. Here, we show that the RNA binding protein (RBP), heterogeneous nuclear ribonucleoprotein Q (HNRNPQ)/SYNCRIP is required to stimulate early events in autophagosome biogenesis, in particular the induction of VPS34 kinase by ULK1-mediated beclin 1 phosphorylation. The RBPs HNRNPQ and poly(A) binding protein nuclear 1 (PABPN1) form a regulatory network that controls the turnover of distinct autophagy-related (ATG) proteins. We also show that oculopharyngeal muscular dystrophy (OPMD) mutations engender a switch from autophagosome stimulation to autophagosome inhibition by impairing PABPN1 and HNRNPQ control of the level of ULK1. The overexpression of HNRNPQ in OPMD patient-derived cells rescues the defective autophagy in these cells. Our data reveal a regulatory mechanism of autophagy induction that is compromised by PABPN1 disease mutations, and may thus further contribute to their deleterious effects.
Assuntos
Distrofia Muscular Oculofaríngea , Humanos , Distrofia Muscular Oculofaríngea/genética , Distrofia Muscular Oculofaríngea/metabolismo , Autofagossomos/metabolismo , Mutação/genética , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismoRESUMO
BACKGROUND & AIMS: Hepatoblastoma (HB) is a common pediatric malignant liver tumor that is characterized by a low level of genetic mutations. Alternative splicing (AS) has been shown to be closely associated with cancer progression, especially in tumors with a low mutational burden. However, the role of AS in HB remains unknown. METHODS: Transcriptome sequencing was performed on 5 pairs of HB tissues and matched non-tumor tissues to delineate the AS landscape in HB. AS events were validated in 92 samples from 46 patients. RNA pull-down and RNA immunoprecipitation assays were carried out to identify splicing factors that regulate the AS of small nucleolar RNA host genes (SNHG). Patient-derived organoids (PDOs) were established to investigate the role of the splicing factor polyadenylate-binding nuclear protein 1 (PABPN1). RESULTS: This study uncovered aberrant alternative splicing in HB, including lncRNAs from SNHG family that undergo intron retention in HB. Further investigations revealed that PABPN1, a significantly upregulated RNA binding protein, interacts with splicing machinery in HB, inducing the intron retention of these SNHG RNAs and the downregulation of intronic small nucleolar RNAs (snoRNAs). Functionally, PABPN1 acts as an oncofetal splicing regulator in HB by promoting cell proliferation and DNA damage repair via inducing the intron retention of SNHG19. Knock-down of PABPN1 increases the cisplatin sensitivity of HB PDOs. CONCLUSIONS: Our findings revealed the role of intron retention in regulating snoRNA expression in hepatoblastoma, explained detailed regulatory mechanism between PABPN1 and the intron retention of SNHG RNAs, and provided insight into the development of new HB treatment options.
Assuntos
Hepatoblastoma , Neoplasias Hepáticas , RNA Longo não Codificante , Criança , Humanos , RNA Nucleolar Pequeno/genética , RNA Nucleolar Pequeno/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Hepatoblastoma/tratamento farmacológico , Hepatoblastoma/genética , Processamento Alternativo/genética , Resistencia a Medicamentos Antineoplásicos/genética , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/genética , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismoRESUMO
Poly(A)-binding protein nuclear 1 (PABPN1) is an RNA-binding protein localized in nuclear speckles, while its alanine (Ala)-expanded variants accumulate as intranuclear aggregates in oculopharyngeal muscular dystrophy. The factors that drive PABPN1 aggregation and its cellular consequences remain largely unknown. Here, we investigated the roles of Ala stretch and poly(A) RNA in the phase transition of PABPN1 using biochemical and molecular cell biology methods. We have revealed that the Ala stretch controls its mobility in nuclear speckles, and Ala expansion leads to aggregation from the dynamic speckles. Poly(A) nucleotide is essential to the early-stage condensation that thereby facilitates speckle formation and transition to solid-like aggregates. Moreover, the PABPN1 aggregates can sequester CFIm25, a component of the pre-mRNA 3'-UTR processing complex, in an mRNA-dependent manner and consequently impair the function of CFIm25 in alternative polyadenylation. In conclusion, our study elucidates a molecular mechanism underlying PABPN1 aggregation and sequestration, which will be beneficial for understanding PABPN1 proteinopathy.
Assuntos
Distrofia Muscular Oculofaríngea , Poliadenilação , Humanos , Alanina/metabolismo , Distrofia Muscular Oculofaríngea/genética , Distrofia Muscular Oculofaríngea/metabolismo , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismo , RNA/metabolismoRESUMO
Nuclear mRNA metabolism is regulated by multiple proteins, which either directly bind to RNA or form multiprotein complexes. The RNA-binding protein ZC3H11A is involved in nuclear mRNA export, NF-κB signaling, and is essential during mouse embryo development. Furthermore, previous studies have shown that ZC3H11A is important for nuclear-replicating viruses. However, detailed biochemical characterization of the ZC3H11A protein has been lacking. In this study, we established the ZC3H11A protein interactome in human and mouse cells. We demonstrate that the nuclear poly(A)-binding protein PABPN1 interacts specifically with the ZC3H11A protein and controls ZC3H11A localization into nuclear speckles. We report that ZC3H11A specifically interacts with the human adenovirus type 5 (HAdV-5) capsid mRNA in a PABPN1-dependent manner. Notably, ZC3H11A uses the same zinc finger motifs to interact with PABPN1 and viral mRNA. Further, we demonstrate that the lack of ZC3H11A alters the polyadenylation of HAdV-5 capsid mRNA. Taken together, our results suggest that the ZC3H11A protein may act as a novel regulator of polyadenylation of nuclear mRNA.
Assuntos
Proteína I de Ligação a Poli(A) , Poliadenilação , Animais , Humanos , Camundongos , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismo , Proteínas de Ligação a Poli(A)/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismoRESUMO
Intron retention is a type of alternative splicing where one or more introns remain unspliced in a polyadenylated transcript. Although many viral systems are known to translate proteins from mRNAs with retained introns, restriction mechanisms generally prevent export and translation of incompletely spliced mRNAs. Here, we provide evidence that the human nuclear poly(A)-binding protein, PABPN1, functions in such restrictions. Using a reporter construct in which nuclear export of an incompletely spliced mRNA is enhanced by a viral constitutive transport element (CTE), we show that PABPN1 depletion results in a significant increase in export and translation from the unspliced CTE-containing transcript. Unexpectedly, we find that inactivation of poly(A)-tail exosome targeting by depletion of PAXT components had no effect on export and translation of the unspliced reporter mRNA, suggesting a mechanism largely independent of nuclear RNA decay. Interestingly, a PABPN1 mutant selectively defective in stimulating poly(A) polymerase elongation strongly enhanced the expression of the unspliced, but not of intronless, reporter transcripts. Analysis of RNA-seq data also revealed that PABPN1 controls the expression of many human genes via intron retention. Notably, PABPN1-dependent intron retention events mostly affected 3'-terminal introns and were insensitive to PAXT and NEXT deficiencies. Our findings thus disclose a role for PABPN1 in restricting nuclear export of intron-retained transcripts and reinforce the interdependence between terminal intron splicing, 3' end processing, and polyadenylation.
Assuntos
Núcleo Celular , Splicing de RNA , Humanos , Íntrons/genética , Transporte Ativo do Núcleo Celular , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , RNA Viral/genética , Expressão Gênica , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismoRESUMO
Immediately after the initial methionine codon, the PABPN1 gene encodes a stretch of 10 alanines, 1 glycine, and 2 alanines. Oculopharyngeal muscular dystrophy (OPMD) is caused by the expansion of the first 10 alanine stretches. The only exception is the missense mutation of glycine at the 12th residue into alanine, which elongates the stretch to 13 alanines by connecting the first and second stretch with the addition of one alanine in between, indicating that the expansion or elongation of the alanine stretch results in OPMD. We report a 77-year-old man with the novel missense mutation c.34Gâ>âT (p.Gly12Trp) in PABPN1 gene whose clinicopathological findings were compatible with OPMD. He presented with slowly progressive bilateral ptosis, dysphagia, and symmetrical proximal dominant muscle weakness. Magnetic resonance imaging revealed selective fat replacement of the tongue, bilateral adductor magnus, and soleus muscles. Immunohistochemistry studies of the muscle biopsy sample revealed PABPN1-posibive aggregates in the myonuclei which have been reported to be specific to OPMD. This is the first OPMD case caused by neither the expansion nor the elongation of alanine stretch. The present case suggests that OPMD may be caused not only by triplet repeats but also by point mutations.
Assuntos
Distrofia Muscular Oculofaríngea , Masculino , Humanos , Idoso , Distrofia Muscular Oculofaríngea/genética , Distrofia Muscular Oculofaríngea/patologia , Mutação Puntual , Alanina/genética , Glicina/genética , Proteína I de Ligação a Poli(A)/genéticaRESUMO
BACKGROUND: Nasopharyngeal carcinoma (NPC), especially the nonkeratinizing type, is a malignant tumor primarily occurring in southern China and Southeast Asia. Chemotherapy (CT) and combined radiotherapy (RT) is used to treat NPC. However, the mortality rate is high in recurrent and metastatic NPC. We developed a molecular marker, analyzed its correlation with clinical characteristics, and assessed the prognostic value among NPC patients with or without chemoradiotherapy. METHODS: A total of 157 NPC patients were included in this study, with 120 undergoing treatment and 37 without treatment. EBER1/2 expression was investigated using in situ hybridization (ISH). Expression of PABPC1, Ki-67, and p53 was detected with immunohistochemistry. The correlations of EBER1/2 and the expression of the three proteins having clinical features and prognosis were evaluated. RESULTS: The expression of PABPC1 was associated with age, recurrence, and treatment but not with gender, TNM classification, or the expression of Ki-67, p53, or EBER. High expression of PABPC1 was associated with poor overall survival (OS) and disease-free survival (DFS) and was an independent predictor depending on multivariate analysis. Comparatively, no significant correlation was observed between the expression of p53, Ki-67, and EBER and survival. In this study, 120 patients received treatments and revealed significantly better OS and DFS than the untreated 37 patients. PABPC1 high expression was an independent predictor of shorter OS in the treated (HR = 4.012 (1.238-13.522), 95% CI, p = 0.021) and the untreated groups (HR = 5.473 (1.051-28.508), 95% CI, p = 0.044). However, it was not an independent predictor of shorter DFS in either the treated or the untreated groups. No significant survival difference was observed between patients with docetaxel-based induction chemotherapy (IC) + concurrent chemoradiotherapy (CCRT) and those with paclitaxel-based IC + CCRT. However, when combined with treatment and PABPC1 expression, patients with paclitaxel-added chemoradiotherapy plus PABPC1 low expression had significantly better OS than those who underwent chemoradiotherapy (p = 0.036). CONCLUSIONS: High expression of PABPC1 is associated with poorer OS and DFS among NPC patients. Patients with PABPC1 having low expression revealed good survival irrespective of the treatment received, indicating that PABPC1 could be a potential biomarker for triaging NPC patients.
Assuntos
Carcinoma Nasofaríngeo , Neoplasias Nasofaríngeas , Proteína I de Ligação a Poli(A) , Humanos , Quimiorradioterapia , Quimioterapia de Indução , Antígeno Ki-67 , Carcinoma Nasofaríngeo/diagnóstico , Carcinoma Nasofaríngeo/terapia , Neoplasias Nasofaríngeas/diagnóstico , Neoplasias Nasofaríngeas/terapia , Paclitaxel/uso terapêutico , Proteínas de Ligação a Poli(A) , Prognóstico , Proteína Supressora de Tumor p53 , Proteína I de Ligação a Poli(A)/genéticaRESUMO
OBJECTIVE: Oculopharyngeal muscular dystrophy (OPMD) is a late-onset inherited neuromuscular disorder, with progressive ptosis and dysphagia as common manifestations. To date, OPMD has rarely been reported among East Asians. The present study summarizes the phenotypic and genotypic features of Chinese patients with OPMD. METHODS: Twenty-one patients with molecularly confirmed OPMD from 9 unrelated families were identified by direct sequencing of the polyadenlyate binding protein nuclear-1 (PABPN1) gene. Immunofluorescence staining of muscle biopsies was conducted to identify the components of protein degradation pathways involved in OPMD. RESULTS: In our cohort, the genetically confirmed OPMD group had a mean age at onset of 50.6 ± 4.2 years (range 45-60 years). Ptosis (42.9%) was the most common initial symptom; patients with ptosis as the first symptom subsequently developed dysphagia within a median time of 5.5 years (range 1-19 years). Evidence of external ophthalmoplegia was found in 38.1% of patients. A total of 33.3% of the patients developed muscle weakness at a median age at onset of 66 years (range 50-70 years), with neck flexor involvement in all patients. Five genotypes were observed in our cohort, including classical (GCG)9-11 repeats in 7 families and non-GCG elongations with additional GCA expansions in 2 families. OPMD muscle biopsies revealed rimmed vacuoles and intranuclear filamentous inclusions. The PABPN1 protein showed substantial accumulation in the nuclei of muscle fiber aggregates and closely colocalized with p62, LC3B and FK2. INTERPRETATION: Our findings indicate wide genetic heterogeneity in OPMD in the Chinese population and demonstrate abnormalities in protein degradation pathways in this disease.
Assuntos
Transtornos de Deglutição , Distrofia Muscular Oculofaríngea , Humanos , Pessoa de Meia-Idade , Idoso , Distrofia Muscular Oculofaríngea/genética , Distrofia Muscular Oculofaríngea/metabolismo , Distrofia Muscular Oculofaríngea/patologia , População do Leste Asiático , Genótipo , Proteína II de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/genéticaRESUMO
Oculopharyngeal muscular dystrophy (OPMD) is a rare muscle disease characterized by an onset of weakness in the pharyngeal and eyelid muscles. The disease is caused by the extension of a polyalanine tract in the Poly(A) Binding Protein Nuclear 1 (PABPN1) protein leading to the formation of intranuclear inclusions or aggregates in the muscle of OPMD patients. Despite numerous studies stressing the deleterious role of nuclear inclusions in cellular and animal OPMD models, their exact contribution to human disease is still unclear. In this study, we used a large and unique collection of human muscle biopsy samples to perform an in-depth analysis of PABPN1 aggregates in relation to age, genotype and muscle status with the final aim to improve our understanding of OPMD physiopathology. Here we demonstrate that age and genotype influence PABPN1 aggregates: the percentage of myonuclei containing PABPN1 aggregates increases with age and the chaperone HSP70 co-localize more frequently with PABPN1 aggregates with a larger polyalanine tract. In addition to the previously described PRMT1 and HSP70 co-factors, we identified new components of PABPN1 aggregates including GRP78/BiP, RPL24 and p62. We also observed that myonuclei containing aggregates are larger than myonuclei without. When comparing two muscles from the same patient, a similar amount of aggregates is observed in different muscles, except for the pharyngeal muscle where fewer aggregates are observed. This could be due to the peculiar nature of this muscle which has a low level of PAPBN1 and contains regenerating fibers. To confirm the fate of PABPN1 aggregates in a regenerating muscle, we generated a xenograft model by transplanting human OPMD muscle biopsy samples into the hindlimb of an immunodeficient mouse. Xenografts from subjects with OPMD displayed regeneration of human myofibers and PABPN1 aggregates were rapidly present-although to a lower extent-after muscle fiber regeneration. Our data obtained on human OPMD samples add support to the dual non-exclusive models in OPMD combining toxic PABPN1 intranuclear inclusions together with PABPN1 loss of function which altogether result in this late-onset and muscle selective disease.
Assuntos
Distrofia Muscular Oculofaríngea , Humanos , Camundongos , Animais , Distrofia Muscular Oculofaríngea/genética , Distrofia Muscular Oculofaríngea/patologia , Corpos de Inclusão Intranuclear/metabolismo , Corpos de Inclusão Intranuclear/patologia , Xenoenxertos , Modelos Animais de Doenças , Chaperonas Moleculares/metabolismo , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismo , Proteína-Arginina N-Metiltransferases/metabolismo , Proteínas Repressoras/metabolismoRESUMO
Read-through fusion transcripts have recently been identified as chimeric RNAs and have since been linked to tumour growth in some cases. Many fusion genes generated by chromosomal rearrangements have been described in glioblastoma. However, read-through fusion transcripts between neighbouring genes in glioblastoma remain unexplored. We performed paired-end RNA-seq of rat C6 glioma cells and normal cells and discovered a read-through fusion transcript Bcl2l2-Pabpn1 in which exon 3 of Bcl-2-like protein 2 (Bcl2l2) fused to exon 2 of Polyadenylate-binding protein 1 (Pabpn1). This fusion transcript was found in both human glioblastoma and normal cells. Unlike other fusions reported in glioblastoma, Bcl2l2-Pabpn1 appeared to result from RNA processing rather than genomic rearrangement. Bcl2l2-Pabpn1 fusion transcript encoded a fusion protein with BH4, BCL and RRM domains. Functionally, Bcl2l2-Pabpn1 knockdown by targeting its fusion junction decreased its expression, and suppressed cell proliferation, migration and invasion in vitro. Mechanistically, Bcl2l2-Pabpn1 blocked Bax activity and activated PI3K/AKT pathway to promote glioblastoma progression. Together, our work characterized a glioblastoma-associated Bcl2l2-Pabpn1 fusion transcript shared by humans and rats.
Assuntos
Glioblastoma , Glioma , Animais , Proteínas Reguladoras de Apoptose/metabolismo , Proliferação de Células/genética , Glioblastoma/patologia , Glioma/genética , Humanos , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Proteína I de Ligação a Poli(A)/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Processamento Pós-Transcricional do RNA , RatosRESUMO
Plenty of pieces of evidence suggest that the resistance to radiotherapy greatly influences the therapeutic effect in cervical cancer (CCa). MicroRNAs (miRNAs) have been reported to regulate cellular processes by acting as tumor suppressors or promoters, thereby driving radioresistance or radiosensitivity. Meanwhile, it has been reported that microRNA-1323 (miR-1323) widely participates in cancer progression and radiotherapy effects. However, the role of miR-1323 is still not clear in CCa. Hence, in this study, we are going to investigate the molecular mechanism of miR-1323 in CCa cells. In the beginning, miR-1323 was found aberrantly upregulated in CCa cells via RT-qPCR assay. Functional assays indicated that miR-1323 was transferred by cancer-associated fibroblasts-secreted (CAFs-secreted) exosomes and miR-1323 downregulation suppressed cell proliferation, migration, invasion, and increased cell radiosensitivity in CCa. Mechanism assays demonstrated that miR-1323 targeted poly(A)-binding protein nuclear 1 (PABPN1). Besides, PABPN1 recruited insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) to regulate glycogen synthase kinase 3 beta (GSK-3ß) and influenced Wnt/ß-catenin signaling pathway. Therefore, rescue experiments were implemented to validate that PABPN1 overexpression rescued the inhibited cancer development and radioresistance induced by the miR-1323 inhibitor. In conclusion, miR-1323 was involved in CCa progression and radioresistance which might provide a novel insight for CCa treatment.
Assuntos
Fibroblastos Associados a Câncer , Exossomos , MicroRNAs , Neoplasias do Colo do Útero , Fibroblastos Associados a Câncer/metabolismo , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Exossomos/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Glicogênio Sintase Quinase 3 beta/metabolismo , Humanos , MicroRNAs/metabolismo , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismo , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/radioterapia , Via de Sinalização Wnt/genética , beta Catenina/metabolismoRESUMO
Aging-associated muscle wasting is regulated by multiple molecular processes, whereby aberrant mRNA processing regulation induces muscle wasting. The poly(A)-binding protein nuclear 1 (PABPN1) regulates polyadenylation site (PAS) utilization, in the absence of PABPN1 the alternative polyadenylation (APA) is utilized. Reduced PABPN1 levels induce muscle wasting where the expression of cellular processes regulating protein homeostasis, the ubiquitin-proteasome system, and translation, are robustly dysregulated. Translation is affected by mRNA levels, but PABPN1 impact on translation is not fully understood. Here we show that a persistent reduction in PABPN1 levels led to a significant loss of translation efficiency. RNA-sequencing of rRNA-depleted libraries from polysome traces revealed reduced mRNA abundance across ribosomal fractions, as well as reduced levels of small RNAs. We show that the abundance of translated mRNAs in the polysomes correlated with PAS switches at the 3'-UTR. Those mRNAs are enriched in cellular processes that are essential for proper muscle function. This study suggests that the effect of PABPN1 on translation efficiency impacts protein homeostasis in aging-associated muscle atrophy.
Assuntos
Proteína I de Ligação a Poli(A) , Poliadenilação , Regiões 3' não Traduzidas , Humanos , Músculo Esquelético/metabolismo , Atrofia Muscular/patologia , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismo , Biossíntese de Proteínas , RNA Mensageiro/metabolismo , Ribossomos/genéticaRESUMO
BACKGROUND: Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant, late-onset myopathy characterized by ptosis, dysphagia, and progressive proximal limb muscle weakness. The disease is produced by a short expansion of the (GCN)n triplet in the PABPN1 gene. The size of expansion has been correlated to the disease onset and severity. We report the clinical features of a large cohort of OPMD patients harboring the (GCN)15 allele from the Canary Islands. METHODS: A retrospective observational study was performed analyzing the clinical, demographic, and genetic data of 123 OPMD patients. Clinical data from this cohort were compared with clinical data collected in a large European study including 139 OPMD patients. RESULTS: A total of 113 patients (94.2%) carried the (GCN)15 expanded PABN1 allele. Age of symptoms' onset was 45.1 years. The most frequent symptom at onset was ptosis (85.2%) followed by dysphagia (12%). The severity of the disease was milder in the Canary cohort compared to European patients as limb weakness (35.1% vs. 50.4%), the proportion of patients that require assistance for walking or use a wheelchair (9.3% vs. 27.4%), and needed of surgery because of severe dysphagia (4.6% vs. 22.8%) was higher in the European cohort. CONCLUSIONS: Nearly 95% of patients with OPMD from the Canary Islands harbored the (GCN)15 expanded allele supporting a potential founder effect. Disease progression seemed to be milder in the (GCN)15 OPMD Canary cohort than in other cohorts with shorter expansions suggesting that other factors, apart from the expansion size, could be involved in the progression of the disease.
Assuntos
Transtornos de Deglutição , Distrofia Muscular Oculofaríngea , Estudos de Coortes , Transtornos de Deglutição/genética , Humanos , Pessoa de Meia-Idade , Debilidade Muscular/etiologia , Distrofia Muscular Oculofaríngea/diagnóstico , Distrofia Muscular Oculofaríngea/genética , Proteína I de Ligação a Poli(A)/genética , EspanhaRESUMO
Influenza A virus (IAV) is a human-infecting pathogen with a history of causing seasonal epidemics and on several occasions worldwide pandemics. Infection by IAV causes a dramatic decrease in host mRNA translation, whereas viral mRNAs are efficiently translated. The IAV mRNAs have a highly conserved 5'-untranslated region (5'UTR) that is rich in adenosine residues. We show that the human polyadenylate binding protein 1 (PABP1) binds to the 5'UTR of the viral mRNAs. The interaction of PABP1 with the viral 5'UTR makes the translation of viral mRNAs more resistant to canonical cap-dependent translation inhibition than model mRNAs. Additionally, PABP1 bound to the viral 5'UTR can recruit eIF4G in an eIF4E-independent manner. These results indicate that PABP1 bound to the viral 5'UTR may promote eIF4E-independent translation initiation.