1
|
Wang C, Ma H, Baserga SJ, Pederson T, Huang S. Nucleolar structure connects with global nuclear organization. Mol Biol Cell 2023; 34:ar114. [PMID: 37610836 PMCID: PMC10846622 DOI: 10.1091/mbc.e23-02-0062] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 08/15/2023] [Accepted: 08/16/2023] [Indexed: 08/25/2023] Open
Abstract
The nucleolus is a multifunctional nuclear body. To tease out the roles of nucleolar structure without resorting to the use of multi-action drugs, we knocked down the RNA polymerase I subunit RPA194 in HeLa cells by siRNA. Loss of RPA194 resulted in nucleolar-structural segregation and effects on both nucleolus-proximal and distal-nuclear components. The perinucleolar compartment was disrupted, centromere clustering around nucleoli was significantly reduced, and the intranuclear locations of specific genomic loci were altered. Moreover, Cajal bodies, distal from nucleoli, underwent morphological and some compositional changes. In comparison, when the preribosomal RNA-processing factor, UTP4, was knocked down, neither nucleolar segregation nor the intranuclear effects were observed, demonstrating that the changes of nucleolar proximal and distal nuclear domains in RPA194 knockdown cells unlikely arise from a cessation of ribosome synthesis, rather from the consequence of nucleolar-structure alteration. These findings point to a commutative system that links nucleolar structure to the maintenance and spatial organization of certain nuclear domains and genomic loci.
Collapse
Affiliation(s)
- Chen Wang
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Hanhui Ma
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA 01605
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Susan J. Baserga
- Department of Genetics, Yale School of Medicine, New Haven, CT 06520
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT 06520
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
| | - Thoru Pederson
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Sui Huang
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| |
Collapse
|
2
|
Choi S, Cho N, Kim EM, Kim KK. The role of alternative pre-mRNA splicing in cancer progression. Cancer Cell Int 2023; 23:249. [PMID: 37875914 PMCID: PMC10594706 DOI: 10.1186/s12935-023-03094-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/06/2023] [Indexed: 10/26/2023] Open
Abstract
Alternative pre-mRNA splicing is a critical mechanism that generates multiple mRNA from a single gene, thereby increasing the diversity of the proteome. Recent research has highlighted the significance of specific splicing isoforms in cellular processes, particularly in regulating cell numbers. In this review, we examine the current understanding of the role of alternative splicing in controlling cancer cell growth and discuss specific splicing factors and isoforms and their molecular mechanisms in cancer progression. These isoforms have been found to intricately control signaling pathways crucial for cell cycle progression, proliferation, and apoptosis. Furthermore, studies have elucidated the characteristics and functional importance of splicing factors that influence cell numbers. Abnormal expression of oncogenic splicing isoforms and splicing factors, as well as disruptions in splicing caused by genetic mutations, have been implicated in the development and progression of tumors. Collectively, these findings provide valuable insights into the complex interplay between alternative splicing and cell proliferation, thereby suggesting the potential of alternative splicing as a therapeutic target for cancer.
Collapse
Affiliation(s)
- Sunkyung Choi
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Namjoon Cho
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Eun-Mi Kim
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon, 34114, Republic of Korea.
| | - Kee K Kim
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea.
| |
Collapse
|
3
|
Lu N, Min J, Peng L, Huang S, Chai X, Wang S, Wang J. MiR-297 inhibits tumour progression of liver cancer by targeting PTBP3. Cell Death Dis 2023; 14:564. [PMID: 37633911 PMCID: PMC10460384 DOI: 10.1038/s41419-023-06097-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/11/2023] [Accepted: 08/21/2023] [Indexed: 08/28/2023]
Abstract
Whereas increasing evidences demonstrate that miR-297 contributes to the tumour development and progression, the role of miR-297 and its underlying molecular mechanisms in hepatocellular carcinoma (HCC) was still unclear. Here, we reported that the expression of miR-297 increased significantly in hepG2 cells after the treatment of the conditioned medium of human amniotic epithelial cells(hAECs) which can inhibit the proliferation and migration of hepG2. And the overexpression of miR-297 inhibits the cell proliferation, migration and invasion of HCC cell lines in vitro and suppressed the tumorigenesis of HCC in vivo. Polypyrimidine tract-binding protein 3 (PTBP3) was identified as a direct target gene of miR-297 in HCC cell lines, and mediated the function of miR-297 in HCC cells. In clinical samples, miR-297 levels have a tendency to decrease, but there are no statistically significant differences. Furthermore, in vitro cell experiments confirmed that overexpression of miR-297 could inhibit the PI3K/AKT signaling pathway by down-regulating PTBP3 expression, thereby inhibiting the proliferation, migration and invasion of HCC cells. In conclusion, our results revealed that miR-297 could down-regulate the expression of PTBP3 and inhibit the activation of PI3K/AKT signaling pathway, thereby preventing HCC growth, migration and invasion.
Collapse
Affiliation(s)
- Na Lu
- The Institute of Reproduction and Stem Cell Engineering, School of Basic Medical Sciences, Central South University, Changsha, China
- Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China
| | - Jiali Min
- The Institute of Reproduction and Stem Cell Engineering, School of Basic Medical Sciences, Central South University, Changsha, China
| | - Lin Peng
- Changsha Hospital for Maternal and Child Health Care of Hunan Normal University, Changsha, China
| | - Shengjian Huang
- Hunan Guangxiu Hi-tech Life Technology Co., Ltd., Changsha, China
| | - Xiahua Chai
- The Institute of Reproduction and Stem Cell Engineering, School of Basic Medical Sciences, Central South University, Changsha, China
| | - Susu Wang
- The Institute of Reproduction and Stem Cell Engineering, School of Basic Medical Sciences, Central South University, Changsha, China
| | - Jian Wang
- The Institute of Reproduction and Stem Cell Engineering, School of Basic Medical Sciences, Central South University, Changsha, China.
- Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China.
- National Engineering and Research Center of Human Stem Cells, Changsha, China.
| |
Collapse
|
4
|
Angulo J, Cáceres CJ, Contreras N, Fernández-García L, Chamond N, Ameur M, Sargueil B, López-Lastra M. Polypyrimidine-Tract-Binding Protein Isoforms Differentially Regulate the Hepatitis C Virus Internal Ribosome Entry Site. Viruses 2022; 15:8. [PMID: 36680049 PMCID: PMC9864772 DOI: 10.3390/v15010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 12/03/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Translation initiation of the hepatitis C virus (HCV) mRNA depends on an internal ribosome entry site (IRES) that encompasses most of the 5'UTR and includes nucleotides of the core coding region. This study shows that the polypyrimidine-tract-binding protein (PTB), an RNA-binding protein with four RNA recognition motifs (RRMs), binds to the HCV 5'UTR, stimulating its IRES activity. There are three isoforms of PTB: PTB1, PTB2, and PTB4. Our results show that PTB1 and PTB4, but not PTB2, stimulate HCV IRES activity in HuH-7 and HEK293T cells. In HuH-7 cells, PTB1 promotes HCV IRES-mediated initiation more strongly than PTB4. Mutations in PTB1, PTB4, RRM1/RRM2, or RRM3/RRM4, which disrupt the RRM's ability to bind RNA, abrogated the protein's capacity to stimulate HCV IRES activity in HuH-7 cells. In HEK293T cells, PTB1 and PTB4 stimulate HCV IRES activity to similar levels. In HEK293T cells, mutations in RRM1/RRM2 did not impact PTB1's ability to promote HCV IRES activity; and mutations in PTB1 RRM3/RRM4 domains reduced, but did not abolish, the protein's capacity to stimulate HCV IRES activity. In HEK293T cells, mutations in PTB4 RRM1/RRM2 abrogated the protein's ability to promote HCV IRES activity, and mutations in RRM3/RRM4 have no impact on PTB4 ability to enhance HCV IRES activity. Therefore, PTB1 and PTB4 differentially stimulate the IRES activity in a cell type-specific manner. We conclude that PTB1 and PTB4, but not PTB2, act as IRES transacting factors of the HCV IRES.
Collapse
Affiliation(s)
- Jenniffer Angulo
- Laboratorio de Virología Molecular, Centro de Investigaciones Médicas, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile
- Facultad de Odontología, Universidad Finis Terrae, Santiago 7501015, Chile
| | - C. Joaquín Cáceres
- Laboratorio de Virología Molecular, Centro de Investigaciones Médicas, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile
- Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Nataly Contreras
- Laboratorio de Virología Molecular, Centro de Investigaciones Médicas, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile
- Facultad de Medicina Veterinaria y Agronomía, Universidad de Las Américas, Santiago 7500975, Chile
| | - Leandro Fernández-García
- Laboratorio de Virología Molecular, Centro de Investigaciones Médicas, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile
| | - Nathalie Chamond
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8038, Laboratoire CiTCoM, Université Paris Cité, 75006 Paris, France
| | - Melissa Ameur
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8038, Laboratoire CiTCoM, Université Paris Cité, 75006 Paris, France
| | - Bruno Sargueil
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8038, Laboratoire CiTCoM, Université Paris Cité, 75006 Paris, France
| | - Marcelo López-Lastra
- Laboratorio de Virología Molecular, Centro de Investigaciones Médicas, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile
| |
Collapse
|
5
|
Duan L, Wang J, Zhang D, Yuan Y, Tang L, Zhou Y, Jiang X. Immune-Related miRNA-195-5p Inhibits the Progression of Lung Adenocarcinoma by Targeting Polypyrimidine Tract-Binding Protein 1. Front Oncol 2022; 12:862564. [PMID: 35600383 PMCID: PMC9117652 DOI: 10.3389/fonc.2022.862564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose Lung adenocarcinoma (LUAD) is the most common type of cancer and the leading cause of cancer-related death worldwide, resulting in a huge economic and social burden. MiRNA-195-5p plays crucial roles in the initiation and progression of cancer. However, the significance of the miRNA-195-5p/polypyrimidine tract-binding protein 1 (miRNA-195-5p/PTBP1) axis in the progression of lung adenocarcinoma (LUAD) remains unclear. Methods Data were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The starBase database was employed to examine the expression of miRNA-195-5p, while the Kaplan–Meier plotter, UALCAN, and Gene Expression Profiling Interactive Analysis (GEPIA) databases were utilized to analyze the tumor stage and prognostic value of miRNA and PTBP1. Quantitative reverse transcription-polymerase chain reaction assay was conducted to detect the expression levels of miRNA-195-5p in LUAD cell lines and tissues. The effects of miRNA-195-5p on cell proliferation and migration were examined using the cell growth curve, clone information, transwell assays, and wound healing assays. Results We found that miRNA-195-5p was down-regulated in LUAD cancer and cell lines. Importantly, its low levels were related to the tumor stage, lymph node metastasis, and poor prognosis in LUAD. Overexpression of miR-195-5p significantly inhibited cell growth and migration promotes cell apoptosis. Further study revealed that PTBP1 is a target gene of miRNA-195-5p, and overexpression of miRNA-195-5p inhibited the progression of LUAD by inhibiting PTBP1 expression. MiRNA-195-5p expression was related to immune infiltration in lung adenocarcinoma. Moreover, PTBP1 was negatively correlated with diverse immune cell infiltration and drug sensitivity. Conclusion Our findings uncover a pivotal mechanism that miRNA-195-5p by modulate PTBP1 expression to inhibit the progression of LUAD. MiRNA-195-5p could be a novel diagnostic and prognostic molecular marker for LUAD.
Collapse
Affiliation(s)
- Lincan Duan
- Department of Thoracic Surgery, The Third Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Juan Wang
- Department of Thoracic Surgery, The Third Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Dahang Zhang
- Department of Thoracic Surgery, The Third Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Yixiao Yuan
- Department of Thoracic Surgery, The Third Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Lin Tang
- Department of Thoracic Surgery, The Third Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Yongchun Zhou
- Molecular Diagnostic Center, The Third Affiliated Hospital of Kunming Medical University, Kunming, China
- *Correspondence: Yongchun Zhou, ; Xiulin Jiang,
| | - Xiulin Jiang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Kunming, China
- *Correspondence: Yongchun Zhou, ; Xiulin Jiang,
| |
Collapse
|
6
|
Yu L, Majerciak V, Zheng ZM. HPV16 and HPV18 Genome Structure, Expression, and Post-Transcriptional Regulation. Int J Mol Sci 2022; 23:ijms23094943. [PMID: 35563334 PMCID: PMC9105396 DOI: 10.3390/ijms23094943] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 12/18/2022] Open
Abstract
Human papillomaviruses (HPV) are a group of small non-enveloped DNA viruses whose infection causes benign tumors or cancers. HPV16 and HPV18, the two most common high-risk HPVs, are responsible for ~70% of all HPV-related cervical cancers and head and neck cancers. The expression of the HPV genome is highly dependent on cell differentiation and is strictly regulated at the transcriptional and post-transcriptional levels. Both HPV early and late transcripts differentially expressed in the infected cells are intron-containing bicistronic or polycistronic RNAs bearing more than one open reading frame (ORF), because of usage of alternative viral promoters and two alternative viral RNA polyadenylation signals. Papillomaviruses proficiently engage alternative RNA splicing to express individual ORFs from the bicistronic or polycistronic RNA transcripts. In this review, we discuss the genome structures and the updated transcription maps of HPV16 and HPV18, and the latest research advances in understanding RNA cis-elements, intron branch point sequences, and RNA-binding proteins in the regulation of viral RNA processing. Moreover, we briefly discuss the epigenetic modifications, including DNA methylation and possible APOBEC-mediated genome editing in HPV infections and carcinogenesis.
Collapse
|
7
|
Dai S, Wang C, Zhang C, Feng L, Zhang W, Zhou X, He Y, Xia X, Chen B, Song W. PTB: Not just a polypyrimidine tract-binding protein. J Cell Physiol 2022; 237:2357-2373. [PMID: 35288937 DOI: 10.1002/jcp.30716] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/19/2022] [Accepted: 02/22/2022] [Indexed: 01/21/2023]
Abstract
Polypyrimidine tract-binding protein (PTB), as a member of the heterogeneous nuclear ribonucleoprotein family, functions by rapidly shuttling between the nucleus and the cytoplasm. PTB is involved in the alternative splicing of pre-messenger RNA (mRNA) and almost all steps of mRNA metabolism. PTB regulation is organ-specific; brain- or muscle-specific microRNAs and long noncoding RNAs partially contribute to regulating PTB, thereby modulating many physiological and pathological processes, such as embryonic development, cell development, spermatogenesis, and neuron growth and differentiation. Previous studies have shown that PTB knockout can inhibit tumorigenesis and development. The knockout of PTB in glial cells can be reprogrammed into functional neurons, which shows great promise in the field of nerve regeneration but is controversial.
Collapse
Affiliation(s)
- Shirui Dai
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China.,Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, P. R. China
| | - Chao Wang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Cheng Zhang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Lemeng Feng
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Wulong Zhang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Xuezhi Zhou
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Ye He
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Xiaobo Xia
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Baihua Chen
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, P. R. China
| | - Weitao Song
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| |
Collapse
|
8
|
Wang Z, Zhou S, Zhao J, Nie S, Sun J, Gao X, Lenahan C, Lin Z, Huang Y, Chen G. Tobacco Smoking Increases Methylation of Polypyrimidine Tract Binding Protein 1 Promoter in Intracranial Aneurysms. Front Aging Neurosci 2021; 13:688179. [PMID: 34295240 PMCID: PMC8292010 DOI: 10.3389/fnagi.2021.688179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/14/2021] [Indexed: 11/20/2022] Open
Abstract
DNA methylation at the gene promoter region is reportedly involved in the development of intracranial aneurysm (IA). This study aims to investigate the methylation levels of polypyrimidine tract-binding protein 1 (PTBP1) in IA, as well as its potential to predict IA. Forty-eight patients with IA and 48 age- and sex-matched healthy controls were recruited into this study. Methylation levels of CpG sites were determined via bisulfite pyrosequencing. The PTBP1 levels in the blood were determined using a real-time quantitative reverse transcription-polymerase chain reaction test. Significant differences were found between IAs and controls in CpG1 (p = 0.001), CpG2 (p < 0.001), CpG3 (p = 0.037), CpG4 (p = 0.003), CpG5 (p = 0.006), CpG6 (p = 0.02), and mean methylation (p < 0.001). The mRNA level of PTBP1 in the blood was much lower in IAs compared with controls (p = 0.002), and the PTBP1 expression was significantly associated with DNA methylation promoter levels in individuals (r = −0.73, p < 0.0001). In addition, stratification analysis comparing smokers and non-smokers revealed that tobacco smokers had significantly higher levels of DNA methylation in PTBP1 than non-smokers (p = 0.002). However, no statistical difference in PTBP1 methylation was found between ruptured and unruptured IA groups (p > 0.05). The ROC analyses of curves revealed that PTBP1 methylation may be a predictor of IA regardless of sex (both sexes, area under curve (AUC) = 0.78, p < 0.0001; male, AUC = 0.76, p = 0.002; female, AUC = 0.79, p < 0.0001). These findings suggest that long-term tobacco smoke exposure led to DNA methylation in the promoter region of the PTBP1 gene, which further decreased PTBP1 gene expression and participated in the pathogenesis of IA. The methylation of PTBP1 may be a potential predictive marker for the occurrence of IA.
Collapse
Affiliation(s)
- Zhepei Wang
- Department of Neurosurgery, Ningbo Hospital, Zhejiang University School of Medicine, Ningbo, China.,Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shengjun Zhou
- Department of Neurosurgery, Ningbo Hospital, Zhejiang University School of Medicine, Ningbo, China.,Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jikuang Zhao
- Department of Neurosurgery, Ningbo Hospital, Zhejiang University School of Medicine, Ningbo, China.,Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Sheng Nie
- Department of Neurosurgery, Ningbo Hospital, Zhejiang University School of Medicine, Ningbo, China
| | - Jie Sun
- Department of Neurosurgery, Ningbo Hospital, Zhejiang University School of Medicine, Ningbo, China
| | - Xiang Gao
- Department of Neurosurgery, Ningbo Hospital, Zhejiang University School of Medicine, Ningbo, China
| | - Cameron Lenahan
- Burrell College of Osteopathic Medicine, Las Cruces, NM, United States
| | - Zhiqin Lin
- Department of Neurosurgery, Ningbo Hospital, Zhejiang University School of Medicine, Ningbo, China
| | - Yi Huang
- Department of Neurosurgery, Ningbo Hospital, Zhejiang University School of Medicine, Ningbo, China.,Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Gao Chen
- Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
9
|
Martelly W, Fellows B, Kang P, Vashisht A, Wohlschlegel JA, Sharma S. Synergistic roles for human U1 snRNA stem-loops in pre-mRNA splicing. RNA Biol 2021; 18:2576-2593. [PMID: 34105434 DOI: 10.1080/15476286.2021.1932360] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
During spliceosome assembly, interactions that bring the 5' and 3' ends of an intron in proximity are critical for the production of mature mRNA. Here, we report synergistic roles for the stem-loops 3 (SL3) and 4 (SL4) of the human U1 small nuclear RNA (snRNA) in maintaining the optimal U1 snRNP function, and formation of cross-intron contact with the U2 snRNP. We find that SL3 and SL4 bind distinct spliceosomal proteins and combining a U1 snRNA activity assay with siRNA-mediated knockdown, we demonstrate that SL3 and SL4 act through the RNA helicase UAP56 and the U2 protein SF3A1, respectively. In vitro analysis using UV crosslinking and splicing assays indicated that SL3 likely promotes the SL4-SF3A1 interaction leading to enhancement of A complex formation and pre-mRNA splicing. Overall, these results highlight the vital role of the distinct contacts of SL3 and SL4 in bridging the pre-mRNA bound U1 and U2 snRNPs during the early steps of human spliceosome assembly.
Collapse
Affiliation(s)
- William Martelly
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ, USA.,School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Bernice Fellows
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ, USA
| | - Paul Kang
- Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health-Phoenix, University of Arizona, Phoenix, AZ, USA
| | - Ajay Vashisht
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Shalini Sharma
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ, USA
| |
Collapse
|
10
|
Cerasuolo A, Buonaguro L, Buonaguro FM, Tornesello ML. The Role of RNA Splicing Factors in Cancer: Regulation of Viral and Human Gene Expression in Human Papillomavirus-Related Cervical Cancer. Front Cell Dev Biol 2020; 8:474. [PMID: 32596243 PMCID: PMC7303290 DOI: 10.3389/fcell.2020.00474] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 05/20/2020] [Indexed: 12/12/2022] Open
Abstract
The spliceosomal complex components, together with the heterogeneous nuclear ribonucleoproteins (hnRNPs) and serine/arginine-rich (SR) proteins, regulate the process of constitutive and alternative splicing, the latter leading to the production of mRNA isoforms coding multiple proteins from a single pre-mRNA molecule. The expression of splicing factors is frequently deregulated in different cancer types causing the generation of oncogenic proteins involved in cancer hallmarks. Cervical cancer is caused by persistent infection with oncogenic human papillomaviruses (HPVs) and constitutive expression of viral oncogenes. The aberrant activity of hnRNPs and SR proteins in cervical neoplasia has been shown to trigger the production of oncoproteins through the processing of pre-mRNA transcripts either derived from human genes or HPV genomes. Indeed, hnRNP and SR splicing factors have been shown to regulate the production of viral oncoprotein isoforms necessary for the completion of viral life cycle and for cell transformation. Target-therapy strategies against hnRNPs and SR proteins, causing simultaneous reduction of oncogenic factors and inhibition of HPV replication, are under development. In this review, we describe the current knowledge of the functional link between RNA splicing factors and deregulated cellular as well as viral RNA maturation in cervical cancer and the opportunity of new therapeutic strategies.
Collapse
Affiliation(s)
| | | | | | - Maria Lina Tornesello
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumouri IRCCS–Fondazione G. Pascale, Naples, Italy
| |
Collapse
|
11
|
Park S, Brugiolo M, Akerman M, Das S, Urbanski L, Geier A, Kesarwani AK, Fan M, Leclair N, Lin KT, Hu L, Hua I, George J, Muthuswamy SK, Krainer AR, Anczuków O. Differential Functions of Splicing Factors in Mammary Transformation and Breast Cancer Metastasis. Cell Rep 2019; 29:2672-2688.e7. [PMID: 31775037 PMCID: PMC6936330 DOI: 10.1016/j.celrep.2019.10.110] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/09/2019] [Accepted: 10/28/2019] [Indexed: 12/28/2022] Open
Abstract
Misregulation of alternative splicing is a hallmark of human tumors, yet to what extent and how it contributes to malignancy are only beginning to be unraveled. Here, we define which members of the splicing factor SR and SR-like families contribute to breast cancer and uncover differences and redundancies in their targets and biological functions. We identify splicing factors frequently altered in human breast tumors and assay their oncogenic functions using breast organoid models. We demonstrate that not all splicing factors affect mammary tumorigenesis in MCF-10A cells. Specifically, the upregulation of SRSF4, SRSF6, or TRA2β disrupts acinar morphogenesis and promotes cell proliferation and invasion in MCF-10A cells. By characterizing the targets of these oncogenic splicing factors, we identify shared spliced isoforms associated with well-established cancer hallmarks. Finally, we demonstrate that TRA2β is regulated by the MYC oncogene, plays a role in metastasis maintenance in vivo, and its levels correlate with breast cancer patient survival.
Collapse
Affiliation(s)
- SungHee Park
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA,These authors contributed equally
| | - Mattia Brugiolo
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA,These authors contributed equally
| | - Martin Akerman
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA,Envisagenics Inc., New York, NY, USA,These authors contributed equally
| | - Shipra Das
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA,These authors contributed equally
| | - Laura Urbanski
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA,Graduate Program in Genetics and Development, UConn Health, Farmington, CT, USA
| | | | | | - Martin Fan
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Nathan Leclair
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA,Graduate Program in Genetics and Development, UConn Health, Farmington, CT, USA
| | - Kuan-Ting Lin
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Leo Hu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Ian Hua
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Joshy George
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA,Institute for Systems Genomics, UConn Health, Farmington, CT, USA
| | - Senthil K. Muthuswamy
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA,Departments of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Adrian R. Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA,Correspondence: (O.A.), (A.R.K.)
| | - Olga Anczuków
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA; Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA; Institute for Systems Genomics, UConn Health, Farmington, CT, USA; Department of Genetics and Genome Sciences, UConn Health, Farmington, CT, USA.
| |
Collapse
|
12
|
PTBP1-mediated regulation of AXL mRNA stability plays a role in lung tumorigenesis. Sci Rep 2019; 9:16922. [PMID: 31729427 PMCID: PMC6858377 DOI: 10.1038/s41598-019-53097-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 10/23/2019] [Indexed: 11/09/2022] Open
Abstract
AXL is expressed in many types of cancer and promotes cancer cell survival, metastasis and drug resistance. Here, we focus on identifying modulators that regulate AXL at the mRNA level. We have previously observed that the AXL promoter activity is inversely correlated with the AXL expression levels, suggesting that post-transcriptional mechanisms exist that down-regulate the expression of AXL mRNA. Here we show that the RNA binding protein PTBP1 (polypyrimidine tract-binding protein) directly targets the 5′-UTR of AXL mRNA in vitro and in vivo. Moreover, we also demonstrate that PTBP1, but not PTBP2, inhibits the expression of AXL mRNA and the RNA recognition motif 1 (RRM1) of PTBP1 is crucial for this interaction. To clarify how PTBP1 regulates AXL expression at the mRNA level, we found that, while the transcription rate of AXL was not significantly different, PTBP1 decreased the stability of AXL mRNA. In addition, over-expression of AXL may counteract the PTBP1-mediated apoptosis. Knock-down of PTBP1 expression could enhance tumor growth in animal models. Finally, PTBP1 was found to be negatively correlated with AXL expression in lung tumor tissues in Oncomine datasets and in tissue micro-array (TMA) analysis. In conclusion, we have identified a molecular mechanism of AXL expression regulation by PTBP1 through controlling the AXL mRNA stability. These findings may represent new thoughts alternative to current approaches that directly inhibit AXL signaling and may eventually help to develop novel therapeutics to avoid cancer metastasis and drug resistance.
Collapse
|
13
|
Kang H, Heo S, Shin JJ, Ji E, Tak H, Ahn S, Lee KJ, Lee EK, Kim W. A miR‐194/PTBP1/CCND3 axis regulates tumor growth in human hepatocellular carcinoma. J Pathol 2019; 249:395-408. [DOI: 10.1002/path.5325] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 06/16/2019] [Accepted: 07/11/2019] [Indexed: 01/05/2023]
Affiliation(s)
- Hoin Kang
- Department of BiochemistryThe Catholic University of Korea, College of Medicine Seoul South Korea
- Institute of Aging and Metabolic DiseasesThe Catholic University of Korea, College of Medicine Seoul South Korea
| | - Sungeun Heo
- Department of Molecular Science and TechnologyAjou University Suwon South Korea
| | - Jung Jae Shin
- Department of Molecular Science and TechnologyAjou University Suwon South Korea
| | - Eunbyul Ji
- Department of BiochemistryThe Catholic University of Korea, College of Medicine Seoul South Korea
| | - Hyosun Tak
- Department of BiochemistryThe Catholic University of Korea, College of Medicine Seoul South Korea
| | - Sojin Ahn
- Department of BiochemistryThe Catholic University of Korea, College of Medicine Seoul South Korea
| | - Kyung Jin Lee
- Department of Convergence Medicine, Asan Institute for Life SciencesUniversity of Ulsan College of Medicine Seoul South Korea
| | - Eun Kyung Lee
- Department of BiochemistryThe Catholic University of Korea, College of Medicine Seoul South Korea
- Institute of Aging and Metabolic DiseasesThe Catholic University of Korea, College of Medicine Seoul South Korea
| | - Wook Kim
- Department of Molecular Science and TechnologyAjou University Suwon South Korea
| |
Collapse
|
14
|
Kamińska K, Białkowska A, Kowalewski J, Huang S, Lewandowska MA. Differential gene methylation patterns in cancerous and non‑cancerous cells. Oncol Rep 2019; 42:43-54. [PMID: 31115550 PMCID: PMC6549081 DOI: 10.3892/or.2019.7159] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/08/2019] [Indexed: 12/11/2022] Open
Abstract
Large-scale projects, such as The Cancer Genome Atlas (TCGA), Human Epigenome Project (HEP) and Human Epigenome Atlas (HEA), provide an insight into DNA methylation and histone modification markers. Changes in the epigenome significantly contribute to the initiation and progression of cancer. The goal of the present study was to characterize the prostate cancer malignant transformation model using the CpG island methylation pattern. The Human Prostate Cancer EpiTect Methyl II Signature PCR Array was used to evaluate the methylation status of 22 genes in prostate cancer cell lines: PC3, PC3M, PC3MPro4 and PC3MLN4, each representing different metastatic potential in vivo. Subsequently, it was ascertained whether DNA methylation plays a role in the expression of these genes in prostate cancer cells. Hypermethylation of APC, DKK3, GPX3, GSTP1, MGMT, PTGS2, RASSF1, TIMP2 and TNFRSF10D resulted in downregulation of their expression in prostate cancer cell lines as compared to WT fibroblasts. Mining of the TCGA data deposited in the MetHC database found increases in the methylation status of these 9 genes in prostate cancer patients, further supporting the role of methylation in altering the expression of these genes in prostate cancer. Future studies are warranted to investigate the role of these proteins in prostate cancer development.
Collapse
Affiliation(s)
- Katarzyna Kamińska
- Department of Molecular Oncology and Genetics, Innovative Medical Forum, The F. Lukaszczyk Oncology Center, Bydgoszcz, Poland
| | - Aneta Białkowska
- Department of Molecular Oncology and Genetics, Innovative Medical Forum, The F. Lukaszczyk Oncology Center, Bydgoszcz, Poland
| | - Janusz Kowalewski
- Department of Thoracic Surgery and Tumors, The Ludwik Rydygier Collegium Medicum, Nicolaus Copernicus University, 85‑796 Bydgoszcz, Poland
| | - Sui Huang
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Marzena A Lewandowska
- Department of Molecular Oncology and Genetics, Innovative Medical Forum, The F. Lukaszczyk Oncology Center, Bydgoszcz, Poland
| |
Collapse
|
15
|
Yap K, Mukhina S, Zhang G, Tan JSC, Ong HS, Makeyev EV. A Short Tandem Repeat-Enriched RNA Assembles a Nuclear Compartment to Control Alternative Splicing and Promote Cell Survival. Mol Cell 2018; 72:525-540.e13. [PMID: 30318443 PMCID: PMC6224606 DOI: 10.1016/j.molcel.2018.08.041] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/31/2018] [Accepted: 08/27/2018] [Indexed: 11/25/2022]
Abstract
Functions of many long noncoding RNAs (lncRNAs) depend on their ability to interact with multiple copies of specific RNA-binding proteins (RBPs). Here, we devised a workflow combining bioinformatics and experimental validation steps to systematically identify RNAs capable of multivalent RBP recruitment. This uncovered a number of previously unknown transcripts encoding high-density RBP recognition arrays within genetically normal short tandem repeats. We show that a top-scoring hit in this screen, lncRNA PNCTR, contains hundreds of pyrimidine tract-binding protein (PTBP1)-specific motifs allowing it to sequester a substantial fraction of PTBP1 in a nuclear body called perinucleolar compartment. Importantly, PNCTR is markedly overexpressed in a variety of cancer cells and its downregulation is sufficient to induce programmed cell death at least in part by stimulating PTBP1 splicing regulation activity. This work expands our understanding of the repeat-containing fraction of the human genome and illuminates a novel mechanism driving malignant transformation of cancer cells. Human genome encodes many transcripts enriched in short tandem repeats (strRNAs) strRNA PNCTR recruits RNA-binding protein PTBP1 to a nuclear body called PNC PNCTR antagonizes splicing regulation function of PTBP1 and promotes cell survival PNCTR is dramatically upregulated in a wide range of cancer cells
Collapse
Affiliation(s)
- Karen Yap
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK
| | - Svetlana Mukhina
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Gen Zhang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Jason S C Tan
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Hong Sheng Ong
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Eugene V Makeyev
- Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK.
| |
Collapse
|
16
|
Li X, Han F, Liu W, Shi X. PTBP1 promotes tumorigenesis by regulating apoptosis and cell cycle in colon cancer. Bull Cancer 2018; 105:1193-1201. [PMID: 30309622 DOI: 10.1016/j.bulcan.2018.08.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 08/07/2018] [Accepted: 08/10/2018] [Indexed: 10/28/2022]
Abstract
Increased expression of polypyrimidine tract-binding protein 1 (PTBP1) has been observed in human ovarian tumors, glioblastomas, and breast cancer, but its biological roles in tumorigenesis is not fully clear. In the present research, we investigated the biological role of PTBP1 in colon cancer. We found that PTBP1 was overexpressed both in colon cancer cell lines and tissues. Tissue microarray analysis (TMA) indicated that low PTBP1 expression predicted a favorable overall survival for colon cancer patients. Using small interfering RNA technology, we found that down-regulation of PTBP1 significantly inhibited colon cancer cell growth/proliferation, and induced cell cycle arrest as well as apoptosis in vitro. Western blot analysis showed that siRNA PTBP1 could up-regulate the expression of cytoC, p53 and Bax as well as down-regulated p85, p-AKT, cyclinD1, CDK4 and Bcl2 compared to the control. Furthermore, Caspase-3 and PARP1 were activated when PTBP1 is knockdown. This study implies that PTBP1 plays an important role in tumorigenesis of colon cancer.
Collapse
Affiliation(s)
- Xiaona Li
- Xinxiang Second People's Hospital, Department of Pharmacy, Xinxiang, PR China
| | - Fei Han
- Army Medical University, College of Preventive Medicine, Key Laboratory of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Institute of Toxicology, Chongqing, China
| | - Wenbin Liu
- Army Medical University, College of Preventive Medicine, Key Laboratory of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Institute of Toxicology, Chongqing, China
| | - Xiaoyan Shi
- Henan University, Institute of Chinese materia medica, Kaifeng, China.
| |
Collapse
|
17
|
Fu X, Xie F, Gong F, Yang Z, Lv X, Li X, Jiao H, Wang Q, Liu X, Yan L, Xiao R. Suppression of PTBP1 signaling is responsible for mesenchymal stem cell induced invasion of low malignancy cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1552-1565. [PMID: 30327198 DOI: 10.1016/j.bbamcr.2018.08.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/03/2018] [Accepted: 08/07/2018] [Indexed: 12/30/2022]
Abstract
Mesenchymal stem cells (MSCs) hold great promise as attractive vehicles to deliver therapeutic agents against cancer, while the cross-talk between MSCs and cancer cells remains controversial. Here in an indirect co-culture system we observed that MSCs induced the malignancy transformation of low malignancy cancer cells HT29 and MCF7, whereas MSCs were reprogrammed by high malignancy cancer cells HCT116 and MDA-MB-231 without exerting an obvious influence on them. We further demonstrated that the RNA-binding protein polypyrimidine tract-binding protein 1 (PTBP1) was suppressed in low malignancy cancer cells co-cultured with MSCs. Moreover, shRNA mediated silencing of PTBP1 could promote the invasiveness of HT29 cells while over-expression of PTBP1 attenuate the MSC-induced invasion of HT29 cells. Our results suggested that differential effects of MSCs on the invasion of cancer cells partially corresponded to PTBP1 expression in cancer cells and the maintenance of biological characteristics in MSCs, which insight could provide a theoretical basis for evaluating the safety of MSC application and PTBP1 targeting in cancer treatment.
Collapse
Affiliation(s)
- Xin Fu
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Fangnan Xie
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Fuxing Gong
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Zhigang Yang
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Xiaoyan Lv
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Xintian Li
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Hu Jiao
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Qian Wang
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Xia Liu
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Li Yan
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China
| | - Ran Xiao
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Road, Beijing 100144, PR China.
| |
Collapse
|
18
|
Urbanski L, Leclair N, Anczuków O. Alternative-splicing defects in cancer: Splicing regulators and their downstream targets, guiding the way to novel cancer therapeutics. WILEY INTERDISCIPLINARY REVIEWS. RNA 2018; 9:e1476. [PMID: 29693319 PMCID: PMC6002934 DOI: 10.1002/wrna.1476] [Citation(s) in RCA: 221] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/27/2018] [Accepted: 03/01/2018] [Indexed: 12/14/2022]
Abstract
Defects in alternative splicing are frequently found in human tumors and result either from mutations in splicing-regulatory elements of specific cancer genes or from changes in the regulatory splicing machinery. RNA splicing regulators have emerged as a new class of oncoproteins and tumor suppressors, and contribute to disease progression by modulating RNA isoforms involved in the hallmark cancer pathways. Thus, dysregulation of alternative RNA splicing is fundamental to cancer and provides a potentially rich source of novel therapeutic targets. Here, we review the alterations in splicing regulatory factors detected in human tumors, as well as the resulting alternatively spliced isoforms that impact cancer hallmarks, and discuss how they contribute to disease pathogenesis. RNA splicing is a highly regulated process and, as such, the regulators are themselves tightly regulated. Differential transcriptional and posttranscriptional regulation of splicing factors modulates their levels and activities in tumor cells. Furthermore, the composition of the tumor microenvironment can also influence which isoforms are expressed in a given cell type and impact drug responses. Finally, we summarize current efforts in targeting alternative splicing, including global splicing inhibition using small molecules blocking the spliceosome or splicing-factor-modifying enzymes, as well as splice-switching RNA-based therapeutics to modulate cancer-specific splicing isoforms. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing.
Collapse
|
19
|
Wang X, Li Y, Fan Y, Yu X, Mao X, Jin F. PTBP1 promotes the growth of breast cancer cells through the PTEN/Akt pathway and autophagy. J Cell Physiol 2018; 233:8930-8939. [PMID: 29856478 PMCID: PMC6175200 DOI: 10.1002/jcp.26823] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 04/30/2018] [Indexed: 12/22/2022]
Abstract
Invasion and migration is the hallmark of malignant tumors as well as the major cause for breast cancer death. The polypyrimidine tract binding, PTB, protein serves as an important model for understanding how RNA binding proteins affect proliferation and invasion and how changes in the expression of these proteins can control complex programs of tumorigenesis. We have investigated some roles of polypyrimidine tract binding protein 1 (PTBP1) in human breast cancer. We found that PTBP1 was upregulated in breast cancer tissues compared with normal tissues and the same result was confirmed in breast cancer cell lines. Knockdown of PTBP1 substantially inhibited tumor cell growth, migration, and invasion. These results suggest that PTBP1 is associated with breast tumorigenesis and appears to be required for tumor cell growth and maintenance of metastasis. We further analyzed the relationship between PTBP1 and clinicopathological parameters and found that PTBP1 was correlated with her‐2 expression, lymph node metastasis, and pathological stage. This will be a novel target for her‐2(+) breast cancer. PTBP1 exerts these effects, in part, by regulating the phosphatase and tensin homolog‐phosphatidylinositol‐4,5‐bisphosphate 3‐kinase/protein kinase B (PTEN‐PI3K/Akt) pathway and autophagy, and consequently alters cell growth and contributes to the invasion and metastasis.
Collapse
Affiliation(s)
- Xu Wang
- Department of Breast Surgery, The First Affiliated Hospital of China Medical University, Shenyang City, Liaoning, China
| | - Yang Li
- Department of Cell Biology, Key Laboratory of Cell Biology, Ministry of Public Health, and Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang, China
| | - Yan Fan
- Department of Pediatrics, The First Affiliated Hospital of China Medical University, Shenyang City, Liaoning, China
| | - Xinmiao Yu
- Department of Breast Surgery, The First Affiliated Hospital of China Medical University, Shenyang City, Liaoning, China
| | - Xiaoyun Mao
- Department of Breast Surgery, The First Affiliated Hospital of China Medical University, Shenyang City, Liaoning, China
| | - Feng Jin
- Department of Breast Surgery, The First Affiliated Hospital of China Medical University, Shenyang City, Liaoning, China
| |
Collapse
|
20
|
PTBP1 enhances miR-101-guided AGO2 targeting to MCL1 and promotes miR-101-induced apoptosis. Cell Death Dis 2018; 9:552. [PMID: 29748555 PMCID: PMC5945587 DOI: 10.1038/s41419-018-0551-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/16/2018] [Accepted: 03/22/2018] [Indexed: 12/22/2022]
Abstract
Myeloid cell leukemia 1 (MCL1) is a key anti-apoptotic protein belonging to the BCL-2 protein family. To preserve normal cellular homeostasis, cells must maintain strict control over MCL1 expression. Overexpression of MCL1 has been identified as a key contributor to tumorigenesis, and further enables resistance to a number of anti-cancer chemotherapies. Thus, there is an ongoing interest to develop selective MCL1 inhibitors. In order to better target MCL1, it is essential to understand the molecular mechanisms that regulate MCL1 expression in cells. While MCL1 expression is tightly controlled by multiple mechanisms, the post-transcriptional regulation of MCL1 mRNA is poorly studied. Our previous work identified that polypyrimidine tract binding protein 1 (PTBP1) binds to MCL1 mRNA and represses MCL1 expression by destabilizing MCL1 mRNA. In this report, we show that PTBP1 modulates MCL1 expression by regulating the microRNA (miRNA) direction of the miRNA-induced silencing complex (miRISC) to MCL1. We demonstrate that PTBP1 enhances miR-101-guided AGO2 interaction with MCL1, thereby regulating miR-101-induced apoptosis and clonogenic cell survival inhibition in cells. Taken together, not only do these studies expand our understanding on the regulation of MCL1, they also demonstrate that PTBP1 and miRNAs can function cooperatively on a shared target mRNA.
Collapse
|
21
|
Wang ZN, Liu D, Yin B, Ju WY, Qiu HZ, Xiao Y, Chen YJ, Peng XZ, Lu CM. High expression of PTBP1 promote invasion of colorectal cancer by alternative splicing of cortactin. Oncotarget 2018; 8:36185-36202. [PMID: 28404950 PMCID: PMC5482648 DOI: 10.18632/oncotarget.15873] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 01/23/2017] [Indexed: 12/22/2022] Open
Abstract
Polypyrimidine tract-binding protein 1 (PTBP1) involving in almost all steps of mRNA regulation including alternative splicing metabolism during tumorigenesis due to its RNA-binding activity. Initially, we found that high expressed PTBP1 and poor prognosis was interrelated in colorectal cancer (CRC) patients with stages II and III CRC, which widely different in prognosis and treatment, by immunohistochemistry. PTBP1 was also upregulated in colon cancer cell lines. In our study, knockdown of PTBP1 by siRNA transfection decreased cell proliferation and invasion in vitro. Denovirus shRNA knockdown of PTBP1 inhibited colorectal cancer growth in vivo. Furthermore, PTBP1 regulates alternative splicing of many target genes involving in tumorgenesis in colon cancer cells. We confirmed that the splicing of cortactin exon 11 which was only contained in cortactin isoform-a, as a PTBP1 target. Knockdown of PTBP1 decreased the expression of cortactin isoform-a by exclusion of exon 11. Also the mRNA levels of PTBP1 and cortactin isoform-a were cooperatively expressed in colorectal cancer tissues. Knocking down cortactin isoform-a significantly decreased cell migration and invasion in colorectal cancer cells. Overexpression of cortactin isoform-a could rescue PTBP1-knockdown effect of cell motility. In summary the study revealed that PTBP1 facilitates colorectal cancer migration and invasion activities by inclusion of cortactin exon 11.
Collapse
Affiliation(s)
- Zhi-Na Wang
- Department of Gastroenteology and Hepatology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Dan Liu
- Department of Gastroenteology and Hepatology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.,Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Bin Yin
- National Laboratory of Meidical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Wen-Yi Ju
- National Laboratory of Meidical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hui-Zhong Qiu
- Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yi Xiao
- Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yuan-Jia Chen
- Department of Gastroenteology and Hepatology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Xiao-Zhong Peng
- National Laboratory of Meidical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Chong-Mei Lu
- Department of Gastroenteology and Hepatology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| |
Collapse
|
22
|
Hou P, Li L, Chen F, Chen Y, Liu H, Li J, Bai J, Zheng J. PTBP3-Mediated Regulation of ZEB1 mRNA Stability Promotes Epithelial-Mesenchymal Transition in Breast Cancer. Cancer Res 2017; 78:387-398. [PMID: 29187406 DOI: 10.1158/0008-5472.can-17-0883] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 07/28/2017] [Accepted: 11/20/2017] [Indexed: 11/16/2022]
Abstract
The RNA polypyrimidine tract-binding protein PTBP3 is a little studied paralog of PTBP1, which has oncogenic properties. In this study, we demonstrate that PTBP3 induces epithelial-mesenchymal transition (EMT) in breast tumor cells and promotes their invasive growth and metastasis. Elevated expression of PTBP3 associated significantly with lymph node metastasis, advanced histology grade, TNM stage, and poor 5-year overall survival of patients. In human mammary epithelial cells, PTBP3 overexpression was sufficient to induce EMT and to enhance cell migration, invasion, and cancer stem-like cell properties. PTBP3 regulated expression of the EMT regulatory transcription factor ZEB1 by binding the 3'UTR of its mRNA, thereby preventing its degradation. Conversely, ZEB1 ablation blocked the ability of PTBP3 to induce EMT. Overall, our findings define PTBP3 as a regulator of EMT that acts by governing expression of ZEB1, and they establish an oncogenic function of PTBP3, suggesting its candidacy as a theranostic target.Significance: These findings define PTBP3 as a regulator of EMT that acts by governing expression of ZEB1, and they establish an oncogenic function of PTBP3, suggesting its candidacy as a theranostic target. Cancer Res; 78(2); 387-98. ©2017 AACR.
Collapse
Affiliation(s)
- Pingfu Hou
- Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Lin Li
- Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Fang Chen
- Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Yansu Chen
- School of Public Health, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Hui Liu
- School of Pathology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Jingjing Li
- School of Medical Imaging, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Jin Bai
- Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu, China.
| | - Junnian Zheng
- Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu, China. .,Center of Clinical Oncology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.,Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu, China
| |
Collapse
|
23
|
Jin Z, Liang F, Yang J, Mei W. hnRNP I regulates neonatal immune adaptation and prevents colitis and colorectal cancer. PLoS Genet 2017; 13:e1006672. [PMID: 28296893 PMCID: PMC5371387 DOI: 10.1371/journal.pgen.1006672] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 03/29/2017] [Accepted: 03/06/2017] [Indexed: 12/15/2022] Open
Abstract
The intestinal epithelium plays a critical role in host-microbe homeostasis by sensing gut microbes and subsequently initiating proper immune responses. During the neonatal stage, the intestinal epithelium is under immune repression, allowing the transition for newborns from a relatively sterile intra-uterine environment to one that is rich in foreign antigens. The mechanism underlying such immune repression remains largely unclear, but involves downregulation of IRAK1 (interleukin-1 receptor-associated kinase), an essential component of toll-like receptor-mediated NF-κB signaling. We report here that heterogeneous nuclear ribonucleoprotein I (hnRNPI), an RNA binding protein, is essential for regulating neonatal immune adaptation. We generated a mouse model in which hnRNPI is ablated specifically in the intestinal epithelial cells, and characterized intestinal defects in the knockout mice. We found that loss of hnRNPI function in mouse intestinal epithelial cells results in early onset of spontaneous colitis followed by development of invasive colorectal cancer. Strikingly, the epithelium-specific hnRNPI knockout neonates contain aberrantly high IRAK1 protein levels in the colons and fail to develop immune tolerance to environmental microbes. Our results demonstrate that hnRNPI plays a critical role in establishing neonatal immune adaptation and preventing colitis and colorectal cancer. Precisely controlled host-microbe interactions in the gastrointestinal tract are crucial for human overall health and well-being. Dysregulated host responses to gut microbiota are the major cause of autoimmune diseases, inflammatory disorders and cancers. The intestinal epithelium lines the gastrointestinal tract and plays a critical role in sensing gut microbes and subsequently developing a balance of immune tolerance and active immune responses. During the neonatal stage, the immune system in the gastrointestinal tract must be temporally suppressed to accommodate the large number of newly arrived microbes. This process is known as neonatal immune adaptation, and is critical for the establishment of proper host- microbe interactions. We studied the function of hnRNPI in the intestinal epithelium by genetically ablating it in the intestinal epithelial cells of mouse. We found that loss of hnRNPI in intestinal epithelial cells disrupts neonatal immune adaptation, resulting in spontaneous colitis and early onset of invasive colorectal cancer. We show that hnRNPI is required for the neonatal immune suppression through decreasing the protein level of IRAK1, an essential component of toll-like receptor-mediated NF-κB signaling. Our studies demonstrate a critical role of hnRNPI in establishing neonatal immune adaptation and preventing colitis and colorectal cancer.
Collapse
Affiliation(s)
- Zhigang Jin
- Department of comparative Biosciences, College of veterinary medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Feng Liang
- Department of statistics, University of Illinois at Urbana-Champaign, Champaign, Illinois, United States of America
| | - Jing Yang
- Department of comparative Biosciences, College of veterinary medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Wenyan Mei
- Department of comparative Biosciences, College of veterinary medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- * E-mail:
| |
Collapse
|
24
|
Jo YK, Roh SA, Lee H, Park NY, Choi ES, Oh JH, Park SJ, Shin JH, Suh YA, Lee EK, Cho DH, Kim JC. Polypyrimidine tract-binding protein 1-mediated down-regulation of ATG10 facilitates metastasis of colorectal cancer cells. Cancer Lett 2017; 385:21-27. [DOI: 10.1016/j.canlet.2016.11.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/01/2016] [Accepted: 11/01/2016] [Indexed: 12/21/2022]
|
25
|
Jiao H, Dong P, Yan L, Yang Z, Lv X, Li Q, Zong X, Fan J, Fu X, Liu X, Xiao R. TGF-β1 Induces Polypyrimidine Tract-Binding Protein to Alter Fibroblasts Proliferation and Fibronectin Deposition in Keloid. Sci Rep 2016; 6:38033. [PMID: 27897224 PMCID: PMC5126665 DOI: 10.1038/srep38033] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 11/03/2016] [Indexed: 02/04/2023] Open
Abstract
Human dermal fibrotic disease keloid has been a clinical challenge because of its tumour-like growth and the lack of effective therapy. Dysregulated alternative splicing events have been demonstrated in tumours and fibrosis. In the current study, for the first time, it was demonstrated that the splicing regulator polypyrimidine tract-binding protein (PTB), which plays a pivotal role in tumour proliferation, invasion and metastasis, is overexpressed in keloid tissues and fibroblasts. Additionally, TGF-β1 upregulated the expressions of PTB and its upstream regulator, C-MYC, in keloid fibroblasts. Furthermore, we suppressed PTB using siRNA in keloid fibroblasts and in a keloid xenograft nude mouse model. PTB knockdown significantly slowed the proliferation of keloid fibroblasts and accelerated the regression of transplanted keloid tissues, which was accompanied by a shift in the alternative splicing of USP5 and RTN4. Moreover, when PTB was suppressed, there was a reduction in excessive deposition of FN1 and COL3A1 in transplanted keloid tissues. However, only FN1 was downregulated in keloid fibroblasts that were cultured in media supplemented with TGF-β1. Our study provides evidence for the role of PTB in keloid pathophysiology and offers a novel therapeutic target for keloids. Most importantly, the role TGF-β1 regulation of PTB may provide new insights into the mechanisms underlying inflammatory cytokine-induced fibrosis.
Collapse
Affiliation(s)
- Hu Jiao
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Ping Dong
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Li Yan
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Zhigang Yang
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Xiaoyan Lv
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Qiuchen Li
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Xianlei Zong
- Scar Plastic Department of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Jincai Fan
- Scar Plastic Department of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Xin Fu
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Xia Liu
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| | - Ran Xiao
- Research Center of Plastic Surgery Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, P.R. China
| |
Collapse
|
26
|
The impact of RNA binding motif protein 4-regulated splicing cascade on the progression and metabolism of colorectal cancer cells. Oncotarget 2016; 6:38046-60. [PMID: 26506517 PMCID: PMC4741983 DOI: 10.18632/oncotarget.5710] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 10/06/2015] [Indexed: 01/17/2023] Open
Abstract
Dysregulated splicing of pre-messenger (m)RNA is considered a molecular occasion of carcinogenesis. However, the underlying mechanism is complex and remains to be investigated. Herein, we report that the upregulated miR-92a reduced the RNA-binding motif 4 (RBM4) protein expression, leading to the imbalanced expression of the neuronal polypyrimidine tract-binding (nPTB) protein through alternative splicing-coupled nonsense mediated decay (NMD) mechanism. Increase in nPTB protein enhances the relative level of fibroblast growth factor receptor 2 IIIc (FGFR2) and pyruvate kinase M2 (PKM2) transcripts which contribute to the progression and metabolic signature of CRC cells. Expression profiles of RBM4 and downstream alternative splicing events are consistently observed in cancerous tissues compared to adjacent normal tissues. These results constitute a mechanistic understanding of RBM4 on repressing the carcinogenesis of colorectal cells.
Collapse
|
27
|
Abstract
Tumor-associated alterations in RNA splicing result either from mutations in splicing-regulatory elements or changes in components of the splicing machinery. This review summarizes our current understanding of the role of splicing-factor alterations in human cancers. We describe splicing-factor alterations detected in human tumors and the resulting changes in splicing, highlighting cell-type-specific similarities and differences. We review the mechanisms of splicing-factor regulation in normal and cancer cells. Finally, we summarize recent efforts to develop novel cancer therapies, based on targeting either the oncogenic splicing events or their upstream splicing regulators.
Collapse
Affiliation(s)
- Olga Anczuków
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| |
Collapse
|
28
|
La Porta J, Matus-Nicodemos R, Valentín-Acevedo A, Covey LR. The RNA-Binding Protein, Polypyrimidine Tract-Binding Protein 1 (PTBP1) Is a Key Regulator of CD4 T Cell Activation. PLoS One 2016; 11:e0158708. [PMID: 27513449 PMCID: PMC4981342 DOI: 10.1371/journal.pone.0158708] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 06/21/2016] [Indexed: 02/07/2023] Open
Abstract
We have previously shown that the RNA binding protein, polypyrimidine tract-binding protein (PTBP1) plays a critical role in regulating the expression of CD40L in activated CD4 T cells. This is achieved mechanistically through message stabilization at late times of activation as well as by altered distribution of CD40L mRNA within distinct cellular compartments. PTBP1 has been implicated in many different processes, however whether PTBP1 plays a broader role in CD4 T cell activation is not known. To examine this question, experiments were designed to introduce shRNA into primary human CD4 T cells to achieve decreased, but not complete ablation of PTBP1 expression. Analyses of shPTB-expressing CD4 T cells revealed multiple processes including cell proliferation, activation-induced cell death and expression of activation markers and cytokines that were regulated in part by PTBP1 expression. Although there was an overall decrease in the steady-state level of several activation genes, only IL-2 and CD40L appeared to be regulated by PTBP1 at the level of RNA decay suggesting that PTBP1 is critical at different regulatory steps of expression that is gene-specific. Importantly, even though the IL-2 protein levels were reduced in cells with lowered PTBP1, the steady-state level of IL-2 mRNA was significantly higher in these cells suggesting a block at the translational level. Evaluation of T cell activation in shPTB-expressing T cells revealed that PTBP1 was linked primarily to the activation of the PLCγ1/ERK1/2 and the NF-κB pathways. Overall, our results reveal the importance of this critical RNA binding protein in multiple steps of T cell activation.
Collapse
Affiliation(s)
- James La Porta
- Department of Cell Biology and Neuroscience, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Rodrigo Matus-Nicodemos
- Department of Cell Biology and Neuroscience, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Aníbal Valentín-Acevedo
- Department of Cell Biology and Neuroscience, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Lori R. Covey
- Department of Cell Biology and Neuroscience, Rutgers University, New Brunswick, New Jersey, United States of America
- * E-mail:
| |
Collapse
|
29
|
Cui J, Placzek WJ. PTBP1 modulation of MCL1 expression regulates cellular apoptosis induced by antitubulin chemotherapeutics. Cell Death Differ 2016; 23:1681-90. [PMID: 27367564 DOI: 10.1038/cdd.2016.60] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 04/30/2016] [Accepted: 05/30/2016] [Indexed: 01/01/2023] Open
Abstract
Myeloid cell leukemia sequence 1 (MCL1), an anti-apoptotic BCL2 family protein, is a key regulator of intrinsic apoptosis. Normal cells require strict control over MCL1 expression with aberrant MCL1 expression linked to the emergence of various diseases and chemoresistance. Previous studies have detailed how MCL1 expression is regulated by multiple mechanisms both transcriptionally and translationally. However, characterization of the post-transcriptional regulators of MCL1 mRNA is limited. Polypyrimidine tract binding protein 1 (PTBP1) is a known regulator of post-transcriptional gene expression that can control mRNA splicing, translation, stability and localization. Here we demonstrate that PTBP1 binds to MCL1 mRNA and that knockdown of PTBP1 upregulates MCL1 expression in cancer cells by stabilizing MCL1 mRNA and increasing MCL1 mRNA accumulation in cytoplasm. Further, we show that depletion of PTBP1 protects cancer cells from antitubulin agent-induced apoptosis in a MCL1-dependent manner. Taken together, our findings suggest that PTBP1 is a novel regulator of MCL1 mRNA by which it controls apoptotic response to antitubulin chemotherapeutics.
Collapse
Affiliation(s)
- J Cui
- Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - W J Placzek
- Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, AL, USA
| |
Collapse
|
30
|
Cáceres CJ, Contreras N, Angulo J, Vera-Otarola J, Pino-Ajenjo C, Llorian M, Ameur M, Lisboa F, Pino K, Lowy F, Sargueil B, López-Lastra M. Polypyrimidine tract-binding protein binds to the 5' untranslated region of the mouse mammary tumor virus mRNA and stimulates cap-independent translation initiation. FEBS J 2016; 283:1880-901. [PMID: 26972759 DOI: 10.1111/febs.13708] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 03/01/2016] [Accepted: 03/08/2016] [Indexed: 12/23/2022]
Abstract
The 5' untranslated region (UTR) of the full-length mRNA of the mouse mammary tumor virus (MMTV) harbors an internal ribosomal entry site (IRES). In this study, we show that the polypyrimidine tract-binding protein (PTB), an RNA-binding protein with four RNA recognition motifs (RRMs), binds to the MMTV 5' UTR stimulating its IRES activity. There are three isoforms of PTB: PTB1, PTB2, and PTB4. Results show that PTB1 and PTB4, but not PTB2, stimulate MMTV-IRES activity. PTB1 promotes MMTV-IRES-mediated initiation more strongly than PTB4. When expressed in combination, PTB1 further enhanced PTB4 stimulation of the MMTV-IRES, while PTB2 fully abrogates PTB4-induced stimulation. PTB1-induced stimulation of MMTV-IRES was not altered in the presence of PTB4 or PTB2. Mutational analysis reveals that stimulation of MMTV-IRES activity is abrogated when PTB1 is mutated either in RRM1/RRM2 or RRM3/RRM4. In contrast, a PTB4 RRM1/RRM2 mutant has reduced effect over MMTV-IRES activity, while stimulation of the MMTV-IRES activity is still observed when the PTB4 RRM3/RMM4 mutant is used. Therefore, PTB1 and PTB4 differentially stimulate the IRES activity. In contrast, PTB2 acts as a negative modulator of PTB4-induced stimulation of MMTV-IRES. We conclude that PTB1 and PTB4 act as IRES trans-acting factors of the MMTV-IRES.
Collapse
Affiliation(s)
- Carlos J Cáceres
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nataly Contreras
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jenniffer Angulo
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jorge Vera-Otarola
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Constanza Pino-Ajenjo
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Melissa Ameur
- Centre national de la Recherche Scientifique, Unité Mixte de Recherche 8015, Laboratoire de Cristallographie et RMN Biologique, Université Paris Descartes, France
| | - Francisco Lisboa
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Karla Pino
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fernando Lowy
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Bruno Sargueil
- Centre national de la Recherche Scientifique, Unité Mixte de Recherche 8015, Laboratoire de Cristallographie et RMN Biologique, Université Paris Descartes, France
| | - Marcelo López-Lastra
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| |
Collapse
|
31
|
Hollander D, Donyo M, Atias N, Mekahel K, Melamed Z, Yannai S, Lev-Maor G, Shilo A, Schwartz S, Barshack I, Sharan R, Ast G. A network-based analysis of colon cancer splicing changes reveals a tumorigenesis-favoring regulatory pathway emanating from ELK1. Genome Res 2016; 26:541-53. [PMID: 26860615 PMCID: PMC4817777 DOI: 10.1101/gr.193169.115] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 02/04/2016] [Indexed: 12/20/2022]
Abstract
Splicing aberrations are prominent drivers of cancer, yet the regulatory pathways controlling them are mostly unknown. Here we develop a method that integrates physical interaction, gene expression, and alternative splicing data to construct the largest map of transcriptomic and proteomic interactions leading to cancerous splicing aberrations defined to date, and identify driver pathways therein. We apply our method to colon adenocarcinoma and non-small-cell lung carcinoma. By focusing on colon cancer, we reveal a novel tumor-favoring regulatory pathway involving the induction of the transcription factor MYC by the transcription factor ELK1, as well as the subsequent induction of the alternative splicing factor PTBP1 by both. We show that PTBP1 promotes specific RAC1,NUMB, and PKM splicing isoforms that are major triggers of colon tumorigenesis. By testing the pathway's activity in patient tumor samples, we find ELK1,MYC, and PTBP1 to be overexpressed in conjunction with oncogenic KRAS mutations, and show that these mutations increase ELK1 levels via the RAS-MAPK pathway. We thus illuminate, for the first time, a full regulatory pathway connecting prevalent cancerous mutations to functional tumor-inducing splicing aberrations. Our results demonstrate our method is applicable to different cancers to reveal regulatory pathways promoting splicing aberrations.
Collapse
Affiliation(s)
- Dror Hollander
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Maya Donyo
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Nir Atias
- Blavatnik School of Computer Science, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Keren Mekahel
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Zeev Melamed
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Sivan Yannai
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Galit Lev-Maor
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Asaf Shilo
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Schraga Schwartz
- Department of Molecular Genetics, Weizmann Institute, Rehovot 76100, Israel
| | - Iris Barshack
- Department of Pathology, Sheba Medical Center, Ramat Gan 52621, Israel; Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Roded Sharan
- Blavatnik School of Computer Science, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Gil Ast
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| |
Collapse
|
32
|
He X, Arslan AD, Ho TT, Yuan C, Stampfer MR, Beck WT. Involvement of polypyrimidine tract-binding protein (PTBP1) in maintaining breast cancer cell growth and malignant properties. Oncogenesis 2014; 3:e84. [PMID: 24418892 PMCID: PMC3940912 DOI: 10.1038/oncsis.2013.47] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/13/2013] [Accepted: 11/14/2013] [Indexed: 12/12/2022] Open
Abstract
We have investigated some roles of splicing factor polypyrimidine tract-binding protein (PTBP1) in human breast cancer. We found that PTBP1 was upregulated in progressively transformed human mammary epithelial cells (HMECs), as well as in breast tumor cell lines compared with HMECs with finite growth potential and found that the level of PTBP1 correlated with the transformation state of HMECs. Knockdown of PTBP1 expression substantially inhibited tumor cell growth, colony formation in soft agar and in vitro invasiveness of breast cancer cell lines, a result similar to what we have reported in ovarian cancer. However, ectopic expression of PTBP1 (as a PTBP1-EGFP fusion protein) did not enhance the proliferation of immortalized HMEC. Rather, PTBP1 expression promoted anchorage-independent growth of an immortalized HMEC as assessed by increased colony formation in soft agar. In addition, we found that knockdown of PTBP1 expression led to upregulation of the expression of the M1 isoform of pyruvate kinase (PKM1) and increase of the ratio of PKM1 vs PKM2. PKM1 has been reported to promote oxidative phosphorylation and reduce tumorigenesis. Correspondingly, we observed increased oxygen consumption in PTBP1-knockdown breast cancer cells. Together, these results suggest that PTBP1 is associated with breast tumorigenesis and appears to be required for tumor cell growth and maintenance of transformed properties. PTBP1 exerts these effects, in part, by regulating the splicing of pyruvate kinase, and consequently alters glucose metabolism and contributes to the Warburg effect.
Collapse
Affiliation(s)
- X He
- 1] Department of Biopharmaceutical Sciences, College of Pharmacy-Rockford, University of Illinois at Chicago, Rockford, IL, USA [2] Cancer Center, University of Illinois, Chicago, IL, USA
| | - A D Arslan
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - T-T Ho
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - C Yuan
- Department of Biopharmaceutical Sciences, College of Pharmacy-Rockford, University of Illinois at Chicago, Rockford, IL, USA
| | - M R Stampfer
- Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - W T Beck
- 1] Cancer Center, University of Illinois, Chicago, IL, USA [2] Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| |
Collapse
|
33
|
New insights into functional roles of the polypyrimidine tract-binding protein. Int J Mol Sci 2013; 14:22906-32. [PMID: 24264039 PMCID: PMC3856098 DOI: 10.3390/ijms141122906] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 11/13/2013] [Accepted: 11/13/2013] [Indexed: 12/20/2022] Open
Abstract
Polypyrimidine Tract Binding Protein (PTB) is an intensely studied RNA binding protein involved in several post-transcriptional regulatory events of gene expression. Initially described as a pre-mRNA splicing regulator, PTB is now widely accepted as a multifunctional protein shuttling between nucleus and cytoplasm. Accordingly, PTB can interact with selected RNA targets, structural elements and proteins. There is increasing evidence that PTB and its paralog PTBP2 play a major role as repressors of alternatively spliced exons, whose transcription is tissue-regulated. In addition to alternative splicing, PTB is involved in almost all steps of mRNA metabolism, including polyadenylation, mRNA stability and initiation of protein translation. Furthermore, it is well established that PTB recruitment in internal ribosome entry site (IRES) activates the translation of picornaviral and cellular proteins. Detailed studies of the structural properties of PTB have contributed to our understanding of the mechanism of RNA binding by RNA Recognition Motif (RRM) domains. In the present review, we will describe the structural properties of PTB, its paralogs and co-factors, the role in post-transcriptional regulation and actions in cell differentiation and pathogenesis. Defining the multifunctional roles of PTB will contribute to the understanding of key regulatory events in gene expression.
Collapse
|
34
|
Abstract
UNLABELLED Alternative splicing of mRNA precursors enables one gene to produce multiple protein isoforms with differing functions. Under normal conditions, this mechanism is tightly regulated in order for the human genome to generate proteomic diversity sufficient for the functional requirements of complex tissues. When deregulated, however, cancer cells take advantage of this mechanism to produce aberrant proteins with added, deleted, or altered functional domains that contribute to tumorigenesis. Here, we discuss aspects of alternative splicing misregulation in cancer, focusing on splicing events affected by deregulation of regulatory splicing factors and also recent studies identifying mutated components of the splicing machinery. SIGNIFICANCE An increasing body of evidence indicates that aberrant splicing of mRNA precursors leads to production of aberrant proteins that contribute to tumorigenesis. Recent studies show that alterations in cellular concentrations of regulatory splicing factors and mutations in components of the core splicing machinery provide major mechanisms of misregulation of mRNA splicing in cancer. A better understanding of this misregulation will potentially reveal a group of novel drug targets for therapeutic intervention.
Collapse
Affiliation(s)
- Jian Zhang
- Department of Biological Sciences, Columbia University, New York, New York
| | | |
Collapse
|
35
|
Wang D, Zhang H, Li M, Frid MG, Flockton AR, McKeon BA, Yeager ME, Fini MA, Morrell NW, Pullamsetti SS, Velegala S, Seeger W, McKinsey TA, Sucharov CC, Stenmark KR. MicroRNA-124 controls the proliferative, migratory, and inflammatory phenotype of pulmonary vascular fibroblasts. Circ Res 2013; 114:67-78. [PMID: 24122720 DOI: 10.1161/circresaha.114.301633] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
RATIONALE Pulmonary hypertensive remodeling is characterized by excessive proliferation, migration, and proinflammatory activation of adventitial fibroblasts. In culture, fibroblasts maintain a similar activated phenotype. The mechanisms responsible for generation/maintenance of this phenotype remain unknown. OBJECTIVE We hypothesized that aberrant expression of microRNA-124 (miR-124) regulates this activated fibroblast phenotype and sought to determine the signaling pathways through which miR-124 exerts effects. METHODS AND RESULTS We detected significant decreases in miR-124 expression in fibroblasts isolated from calves and humans with severe pulmonary hypertension. Overexpression of miR-124 by mimic transfection significantly attenuated proliferation, migration, and monocyte chemotactic protein-1 expression of hypertensive fibroblasts, whereas anti-miR-124 treatment of control fibroblasts resulted in their increased proliferation, migration, and monocyte chemotactic protein-1 expression. Furthermore, the alternative splicing factor, polypyrimidine tract-binding protein 1, was shown to be a direct target of miR-124 and to be upregulated both in vivo and in vitro in bovine and human pulmonary hypertensive fibroblasts. The effects of miR-124 on fibroblast proliferation were mediated via direct binding to the 3' untranslated region of polypyrimidine tract-binding protein 1 and subsequent regulation of Notch1/phosphatase and tensin homolog/FOXO3/p21Cip1 and p27Kip1 signaling. We showed that miR-124 directly regulates monocyte chemotactic protein-1 expression in pulmonary hypertension/idiopathic pulmonary arterial hypertension fibroblasts. Furthermore, we demonstrated that miR-124 expression is suppressed by histone deacetylases and that treatment of hypertensive fibroblasts with histone deacetylase inhibitors increased miR-124 expression and decreased proliferation and monocyte chemotactic protein-1 production. CONCLUSIONS Stable decreases in miR-124 expression contribute to an epigenetically reprogrammed, highly proliferative, migratory, and inflammatory phenotype of hypertensive pulmonary adventitial fibroblasts. Thus, therapies directed at restoring miR-124 function, including histone deacetylase inhibitors, should be investigated.
Collapse
Affiliation(s)
- Daren Wang
- From the Department of Pediatrics (D.W., H.Z., M.L., M.G.F., A.R.F., B.A.K., M.E.Y., M.A.F.), Department of Medicine (T.A.M., C.C.S.), Department of Medicine and Pediatrics (K.R.S.), Department of Medicine (N.W.M.), Department of Lung Development and Remodeling (S.S.P., S.V., W.S.), Department of Medicine (H.Z.), University of Colorado Anschutz Medical Campus, Aurora, CO; University of Cambridge, Cambridge, United Kingdom (N.W.M.); Addenbrooke's & Papworth Hospitals, Cambridge, United Kingdom (N.W.M.); Max-Planck-Institute for Heart and Lung Research; University of Giessen and Marburg Lung Center, Bad Nauheim, Germany (S.S.P., S.V., W.S.); and Shengjing Hospital of China Medical University, Shenyang, China (H.Z.)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Lin S, Wang MJ, Tseng KY. Polypyrimidine tract-binding protein induces p19(Ink4d) expression and inhibits the proliferation of H1299 cells. PLoS One 2013; 8:e58227. [PMID: 23536791 PMCID: PMC3594294 DOI: 10.1371/journal.pone.0058227] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 02/01/2013] [Indexed: 11/18/2022] Open
Abstract
The expression of polypyrimidine tract-binding protein (PTB) is up-regulated in many types of cancer. Here, we studied the role of PTB in the growth of non small cell lung cancer cells. Data showed that PTB overexpression inhibited the growth of H1299 cells at least by inhibiting DNA synthesis. Quantitative real-time PCR and Western blot analyses showed that PTB overexpression in H1299 cells specifically induced the expression of p19Ink4d, an inhibitor of cyclin-dependent kinase 4. Repression of p19Ink4d expression partially rescued PTB-caused proliferation inhibition. PTB overexpression also inhibited the growth and induced the expression of p19Ink4d mRNA in A549 cells. However, Western blot analyses failed to detect the presence of p19Ink4d protein in A549 cells. To address how PTB induced p19Ink4d in H1299 cells, we showed that PTB might up-regulate the activity of p19Ink4d gene (CDKN2D) promoter. Besides, PTB lacking the RNA recognition motif 3 (RRM3) was less effective in growth inhibition and p19Ink4d induction, suggesting that RNA-binding activity of PTB plays an important role in p19Ink4d induction. However, immunoprecipitation of ribonuclearprotein complexes plus quantitative real-time PCR analyses showed that PTB might not bind p19Ink4d mRNA, suggesting that PTB overexpression might trigger the other RNA-binding protein(s) to bind p19Ink4d mRNA. Subsequently, RNA electrophoretic mobility-shift assays revealed a 300-base segment (designated as B2) within the 3′UTR of p19Ink4d mRNA, with which the cytoplasmic lysates of PTB-overexpressing cells formed more prominent complexes than did control cell lysates. Insertion of B2 into a reporter construct increased the expression of the chimeric luciferase transcripts in transfected PTB-overexpressing cells but not in control cells; conversely, overexpression of B2-containing reporter construct in PTB-overexpressing cells abolished the induction of p19Ink4d mRNA. In sum, we have shown that PTB plays as a negative regulator in H1299 cell proliferation at least by inducing p19Ink4d expression at transcriptional and post-transcriptional levels.
Collapse
Affiliation(s)
- Shankung Lin
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town, Miaoli, Taiwan, Republic of China.
| | | | | |
Collapse
|
37
|
Didiot MC, Hewett J, Varin T, Freuler F, Selinger D, Nick H, Reinhardt J, Buckler A, Myer V, Schuffenhauer A, Guy CT, Parker CN. Identification of cardiac glycoside molecules as inhibitors of c-Myc IRES-mediated translation. ACTA ACUST UNITED AC 2012; 18:407-19. [PMID: 23150017 DOI: 10.1177/1087057112466698] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Translation initiation is a fine-tuned process that plays a critical role in tumorigenesis. The use of small molecules that modulate mRNA translation provides tool compounds to explore the mechanism of translational initiation and to further validate protein synthesis as a potential pharmaceutical target for cancer therapeutics. This report describes the development and use of a click beetle, dual luciferase cell-based assay multiplexed with a measure of compound toxicity using resazurin to evaluate the differential effect of natural products on cap-dependent or internal ribosome entry site (IRES)-mediated translation initiation and cell viability. This screen identified a series of cardiac glycosides as inhibitors of IRES-mediated translation using, in particular, the oncogene mRNA c-Myc IRES. Treatment of c-Myc-dependent cancer cells with these compounds showed a decrease in c-Myc protein associated with a significant modulation of cell viability. These findings suggest that inhibition of IRES-mediated translation initiation may be a strategy to inhibit c-Myc-driven tumorigenesis.
Collapse
|
38
|
Izaguirre DI, Zhu W, Hai T, Cheung HC, Krahe R, Cote GJ. PTBP1-dependent regulation of USP5 alternative RNA splicing plays a role in glioblastoma tumorigenesis. Mol Carcinog 2012; 51:895-906. [PMID: 21976412 PMCID: PMC3319169 DOI: 10.1002/mc.20859] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 06/21/2011] [Accepted: 09/08/2011] [Indexed: 11/08/2022]
Abstract
Aberrant RNA splicing is thought to play a key role in tumorigenesis. The assessment of its specific contributions is limited by the complexity of information derived from genome-wide array-based approaches. We describe how performing splicing factor-specific comparisons using both tumor and cell line data sets may more readily identify physiologically relevant tumor-specific splicing events. Affymetrix exon array data derived from glioblastoma (GBM) tumor samples with defined polypyrimidine tract-binding protein 1 (PTBP1) levels were compared with data from U251 GBM cells with and without PTBP1 knockdown. This comparison yielded overlapping gene sets that comprised only a minor fraction of each data set. The identification of a novel GBM-specific splicing event involving the USP5 gene led us to further examine its role in tumorigenesis. In GBM, USP5 generates a shorter isoform 2 through recognition of a 5' splice site within exon 15. Production of the USP5 isoform 2 was strongly correlated with PTBP1 expression in GBM tumor samples and cell lines. Splicing regulation was consistent with the presence of an intronic PTBP1 binding site and could be modulated through antisense targeting of the isoform 2 splice site to force expression of isoform 1 in GBM cells. The forced expression of USP5 isoform 1 in two GBM cell lines inhibited cell growth and migration, implying an important role for USP5 splicing in gliomagenesis. These results support a role for aberrant RNA splicing in tumorigenesis and suggest that changes in relatively few genes may be sufficient to drive the process.
Collapse
Affiliation(s)
- Daisy I. Izaguirre
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas
- The University of Texas Graduate School of Biomedical Sciences, Houston, Texas
| | - Wen Zhu
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Tao Hai
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Hannah C. Cheung
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas
- The University of Texas Graduate School of Biomedical Sciences, Houston, Texas
| | - Ralf Krahe
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, Texas
- The University of Texas Graduate School of Biomedical Sciences, Houston, Texas
| | - Gilbert J. Cote
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas
- The University of Texas Graduate School of Biomedical Sciences, Houston, Texas
| |
Collapse
|
39
|
Grzmil M, Hemmings BA. Translation Regulation as a Therapeutic Target in Cancer: Figure 1. Cancer Res 2012; 72:3891-900. [DOI: 10.1158/0008-5472.can-12-0026] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
40
|
Cote GJ, Zhu W, Thomas A, Martin E, Murad F, Sharina IG. Hydrogen peroxide alters splicing of soluble guanylyl cyclase and selectively modulates expression of splicing regulators in human cancer cells. PLoS One 2012; 7:e41099. [PMID: 22911749 PMCID: PMC3401163 DOI: 10.1371/journal.pone.0041099] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 06/21/2012] [Indexed: 12/14/2022] Open
Abstract
Background Soluble guanylyl cyclase (sGC) plays a central role in nitric oxide (NO)-mediated signal transduction in the cardiovascular, nervous and gastrointestinal systems. Alternative RNA splicing has emerged as a potential mechanism to modulate sGC expression and activity. C-α1 sGC is an alternative splice form that is resistant to oxidation-induced protein degradation and demonstrates preferential subcellular distribution to the oxidized environment of endoplasmic reticulum (ER). Methodology/Principal Findings Here we report that splicing of C-α1 sGC can be modulated by H2O2 treatment in BE2 neuroblastoma and MDA-MD-468 adenocarcinoma human cells. In addition, we show that the H2O2 treatment of MDA-MD-468 cells selectively decreases protein levels of PTBP1 and hnRNP A2/B1 splice factors identified as potential α1 gene splicing regulators by in silico analysis. We further demonstrate that down-regulation of PTBP1 by H2O2 occurs at the protein level with variable regulation observed in different breast cancer cells. Conclusions/Significance Our data demonstrate that H2O2 regulates RNA splicing to induce expression of the oxidation-resistant C-α1 sGC subunit. We also report that H2O2 treatment selectively alters the expression of key splicing regulators. This process might play an important role in regulation of cellular adaptation to conditions of oxidative stress.
Collapse
Affiliation(s)
- Gilbert J. Cote
- Department of Endocrine Neoplasia and Hormonal Disorders, MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Wen Zhu
- Department of Endocrine Neoplasia and Hormonal Disorders, MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Anthony Thomas
- Department of Internal Medicine/Cardiology, University of Texas Medical School, UTHealth, Houston, Texas, United States of America
| | - Emil Martin
- Department of Internal Medicine/Cardiology, University of Texas Medical School, UTHealth, Houston, Texas, United States of America
| | - Ferid Murad
- Department of Biochemistry and Molecular Biology, George Washington University, Washington, DC, United States of America
| | - Iraida G. Sharina
- Department of Internal Medicine/Cardiology, University of Texas Medical School, UTHealth, Houston, Texas, United States of America
- * E-mail:
| |
Collapse
|
41
|
Shibasaki T, Tokunaga A, Sakamoto R, Sagara H, Noguchi S, Sasaoka T, Yoshida N. PTB Deficiency Causes the Loss of Adherens Junctions in the Dorsal Telencephalon and Leads to Lethal Hydrocephalus. Cereb Cortex 2012; 23:1824-35. [DOI: 10.1093/cercor/bhs161] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
|
42
|
Keppetipola N, Sharma S, Li Q, Black DL. Neuronal regulation of pre-mRNA splicing by polypyrimidine tract binding proteins, PTBP1 and PTBP2. Crit Rev Biochem Mol Biol 2012; 47:360-78. [PMID: 22655688 DOI: 10.3109/10409238.2012.691456] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Alternative splicing patterns are regulated by RNA binding proteins that assemble onto each pre-mRNA to form a complex RNP structure. The polypyrimidine tract binding protein, PTB, has served as an informative model for understanding how RNA binding proteins affect spliceosome assembly and how changes in the expression of these proteins can control complex programs of splicing in tissues. In this review, we describe the mechanisms of splicing regulation by PTB and its function, along with its paralog PTBP2, in neuronal development.
Collapse
Affiliation(s)
- Niroshika Keppetipola
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, USA
| | | | | | | |
Collapse
|
43
|
Brisbin AG, Asmann YW, Song H, Tsai YY, Aakre JA, Yang P, Jenkins RB, Pharoah P, Schumacher F, Conti DV, Duggan DJ, Jenkins M, Hopper J, Gallinger S, Newcomb P, Casey G, Sellers TA, Fridley BL. Meta-analysis of 8q24 for seven cancers reveals a locus between NOV and ENPP2 associated with cancer development. BMC MEDICAL GENETICS 2011; 12:156. [PMID: 22142333 PMCID: PMC3267702 DOI: 10.1186/1471-2350-12-156] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 12/05/2011] [Indexed: 12/20/2022]
Abstract
Background Human chromosomal region 8q24 contains several genes which could be functionally related to cancer, including the proto-oncogene c-MYC. However, the abundance of associations around 128 Mb on chromosome 8 could mask the appearance of a weaker, but important, association elsewhere on 8q24. Methods In this study, we completed a meta-analysis of results from nine genome-wide association studies for seven types of solid-tumor cancers (breast, prostate, pancreatic, lung, ovarian, colon, and glioma) to identify additional associations that were not apparent in any individual study. Results Fifteen SNPs in the 8q24 region had meta-analysis p-values < 1E-04. In particular, the region consisting of 120,576,000-120,627,000 bp contained 7 SNPs with p-values < 1.0E-4, including rs6993464 (p = 1.25E-07). This association lies in the region between two genes, NOV and ENPP2, which have been shown to play a role in tumor development and motility. An additional region consisting of 5 markers from 128,478,000 bp - 128,524,000 (around gene POU5F1B) had p-values < 1E-04, including rs6983267, which had the smallest p-value (p = 6.34E-08). This result replicates previous reports of association between rs6983267 and prostate and colon cancer. Conclusions Further research in this area is warranted as these results demonstrate that the chromosomal region 8q24 may contain a locus that influences general cancer susceptibility between 120,576 and 120,630 kb.
Collapse
Affiliation(s)
- Abra G Brisbin
- Department of Health Sciences Research, Mayo Clinic, Rochester, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Pollock C, Daily K, Nguyen VT, Wang C, Lewandowska MA, Bensaude O, Huang S. Characterization of MRP RNA-protein interactions within the perinucleolar compartment. Mol Biol Cell 2011; 22:858-67. [PMID: 21233287 PMCID: PMC3057709 DOI: 10.1091/mbc.e10-09-0768] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The PNC is a nuclear body that forms in malignant cells. We characterize a newly identified complex in the PNC; determine the dynamics of PNC proteins; and describe the recruitment, localization, and sedimentation properties of PNC components. The perinucleolar compartment (PNC) forms in cancer cells and is highly enriched with a subset of polymerase III RNAs and RNA-binding proteins. Here we report that PNC components mitochondrial RNA–processing (MRP) RNA, pyrimidine tract–binding protein (PTB), and CUG-binding protein (CUGBP) interact in vivo, as demonstrated by coimmunoprecipitation and RNA pull-down experiments. Glycerol gradient analyses show that this complex is large and sediments at a different fraction from known MRP RNA–containing complexes, the MRP ribonucleoprotein ribozyme and human telomerase reverse transcriptase. Tethering PNC components to a LacO locus recruits other PNC components, further confirming the in vivo interactions. These interactions are present both in PNC-containing and -lacking cells. High-resolution localization analyses demonstrate that MRP RNA, CUGBP, and PTB colocalize at the PNC as a reticulated network, intertwining with newly synthesized RNA. Furthermore, green fluorescent protein (GFP)–PTB and GFP-CUGBP show a slower rate of fluorescence recovery after photobleaching at the PNC than in the nucleoplasm, illustrating the different molecular interaction of the complexes associated with the PNC. These findings support a working model in which the MRP RNA–protein complex becomes nucleated at the PNC in cancer cells and may play a role in gene expression regulation at the DNA locus that associates with the PNC.
Collapse
Affiliation(s)
- Callie Pollock
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | | | | | | | | | | | | |
Collapse
|
45
|
Bitel CL, Nathan R, Wong P, Kuppasani S, Matsushita M, Kanazawa H, Frederikse PH. Evidence That ‘Brain-Specific’ Fox-1, Fox-2, and nPTB Alternatively Spliced Isoforms Are Produced in the Lens. Curr Eye Res 2010; 35:1002-11. [DOI: 10.3109/02713683.2010.500114] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
46
|
Llorian M, Schwartz S, Clark TA, Hollander D, Tan LY, Spellman R, Gordon A, Schweitzer AC, de la Grange P, Ast G, Smith CWJ. Position-dependent alternative splicing activity revealed by global profiling of alternative splicing events regulated by PTB. Nat Struct Mol Biol 2010; 17:1114-23. [PMID: 20711188 PMCID: PMC2933513 DOI: 10.1038/nsmb.1881] [Citation(s) in RCA: 200] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Accepted: 06/25/2010] [Indexed: 12/22/2022]
Abstract
To gain global insights into the role of the well-known repressive splicing regulator PTB, we analyzed the consequences of PTB knockdown in HeLa cells using high-density oligonucleotide splice-sensitive microarrays. The major class of identified PTB-regulated splicing event was PTB-repressed cassette exons, but there was also a substantial number of PTB-activated splicing events. PTB-repressed and PTB-activated exons showed a distinct arrangement of motifs with pyrimidine-rich motif enrichment within and upstream of repressed exons but downstream of activated exons. The N-terminal half of PTB was sufficient to activate splicing when recruited downstream of a PTB-activated exon. Moreover, insertion of an upstream pyrimidine tract was sufficient to convert a PTB-activated exon to a PTB-repressed exon. Our results show that PTB, an archetypal splicing repressor, has variable splicing activity that predictably depends upon its binding location with respect to target exons.
Collapse
Affiliation(s)
- Miriam Llorian
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Cobbold LC, Wilson LA, Sawicka K, King HA, Kondrashov AV, Spriggs KA, Bushell M, Willis AE. Upregulated c-myc expression in multiple myeloma by internal ribosome entry results from increased interactions with and expression of PTB-1 and YB-1. Oncogene 2010; 29:2884-91. [PMID: 20190818 DOI: 10.1038/onc.2010.31] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The 5' untranslated region of the proto-oncogene c-myc contains an internal ribosome entry segment (IRES) and c-myc translation can therefore be initiated by internal ribosome entry as well as by cap-dependent mechanisms. It has been shown previously that in patients with multiple myeloma (MM) and in MM-derived cell lines there is a C to T mutation in the c-myc IRES that increases IRES activity and the corresponding synthesis of c-myc protein although it is not fully understood how this occurs. Our data show that two recently identified c-myc IRES trans-acting factors, Y-box binding protein 1 (YB-1) and polypyrimidine tract-binding protein 1 (PTB-1), bind more strongly (approximately 3.5- and 2-fold respectively) to the mutated version of the c-myc IRES and in vitro these proteins exert their effect synergistically to stimulate IRES activity of the mutant IRES 4.5-fold more than the wild-type version. Importantly, we show that there is a strong correlation between the expression of PTB-1, YB-1 and c-myc in MM-derived cell lines, suggesting that by reducing either PTB-1 or YB-1 protein levels it is possible to decrease c-myc expression and inhibit cell proliferation of MM-derived cell lines.
Collapse
Affiliation(s)
- L C Cobbold
- Centre for Biomolecular Sciences, School of Pharmacy, University of Nottingham, Nottingham, UK
| | | | | | | | | | | | | | | |
Collapse
|
48
|
Cheung HC, Hai T, Zhu W, Baggerly KA, Tsavachidis S, Krahe R, Cote GJ. Splicing factors PTBP1 and PTBP2 promote proliferation and migration of glioma cell lines. ACTA ACUST UNITED AC 2009; 132:2277-88. [PMID: 19506066 DOI: 10.1093/brain/awp153] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Polypyrimidine tract-binding protein 1 (PTBP1) is a multi-functional RNA-binding protein that is aberrantly overexpressed in glioma. PTBP1 and its brain-specific homologue polypyrimidine tract-binding protein 2 (PTBP2) regulate neural precursor cell differentiation. However, the overlapping and non-overlapping target transcripts involved in this process are still unclear. To determine why PTBP1 and not PTBP2 would promote glial cell-derived tumours, both PTBP1 and PTBP2 were knocked down in the human glioma cell lines U251 and LN229 to determine the role of these proteins in cell proliferation, migration, and adhesion. Surprisingly, removal of both PTBP1 and PTBP2 slowed cell proliferation, with the double knockdown having no additive effects. Decreased expression of both proteins individually and in combination inhibited cell migration and increased adhesion of cells to fibronectin and vitronectin. A global survey of differential exon expression was performed following PTBP1 knockdown in U251 cells using the Affymetrix Exon Array to identify PTBP1-specific splicing targets that enhance gliomagenesis. In the PTBP1 knockdown, previously determined targets were unaltered in their splicing patterns. A single gene, RTN4 (Nogo) had significantly enhanced inclusion of exon 3 when PTBP1 was removed. Overexpression of the splice isoform containing exon 3 decreased cell proliferation to a similar degree as the removal of PTBP1. These results provide the first evidence that RNA-binding proteins affect the invasive and rapid growth characteristics of glioma cell lines. Its actions on proliferation appear to be mediated, in part, through alternative splicing of RTN4.
Collapse
Affiliation(s)
- Hannah C Cheung
- Department of Endocrine Neoplasia and Hormonal Disorders, University of Texas, M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | | | | | | | | | | | | |
Collapse
|
49
|
Lourenço S, Boni S, Furling D, Cosset FL, Cahour A. A cell-based bicistronic lentiviral reporter system for identification of inhibitors of the hepatitis C virus internal ribosome entry site. J Virol Methods 2009; 158:152-9. [PMID: 19428584 DOI: 10.1016/j.jviromet.2009.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 01/27/2009] [Accepted: 02/05/2009] [Indexed: 01/25/2023]
Abstract
This report describes the development, optimization and implementation of a persistent cell-based system to test inhibitors of hepatitis C (HCV) translation. The assay is based on a heterologous human immunodeficiency virus-1/simian immunodeficiency virus (HIV-1/SIV) lentiviral vector expressing the bicistronic cassette containing the firefly and renilla luciferase genes, respectively, as reporters, and the HCV internal ribosome entry site (IRES) inserted in between, under the control of the cytomegalovirus (CMV) promoter. The drug target in this assay is the HCV IRES, the activity of which leads to modulation of the renilla luciferase gene expression under its control, which is monitored by luminometry. The system has been validated using interferon (IFN), which is still the only consensual antiviral agent against HCV infection, associated with ribavirin. This bicistronic vector, extended to other viral IRESs and assayed in different cell lines, exhibited weak cell tropism, allowing its broad use in gene therapy, which frequently needs a multicistronic transfer vector to follow the expression of a gene of interest inside the target cells with the aid of a reporter, a drug selection marker, or a suicide gene, expressed from the same transcript.
Collapse
Affiliation(s)
- Sofia Lourenço
- Laboratoire de Virologie, CERVI, Unité Propre de Recherche et d'Enseignement Supérieur de l'UPMC, Université Paris 6 EA 2387, IFR 113, Groupe Hospitalier Pitié-Salpêtrière, Paris Cedex 13, France
| | | | | | | | | |
Collapse
|
50
|
Bian Y, Masuda A, Matsuura T, Ito M, Okushin K, Engel AG, Ohno K. Tannic acid facilitates expression of the polypyrimidine tract binding protein and alleviates deleterious inclusion of CHRNA1 exon P3A due to an hnRNP H-disrupting mutation in congenital myasthenic syndrome. Hum Mol Genet 2009; 18:1229-37. [PMID: 19147685 PMCID: PMC2655771 DOI: 10.1093/hmg/ddp023] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We recently reported that the intronic splice-site mutation IVS3-8G>A of CHRNA1 that encodes the muscle nicotinic acetylcholine receptor alpha subunit disrupts binding of a splicing repressor, hnRNP H. This, in turn, results in exclusive inclusion of the downstream exon P3A. The P3A(+) transcript encodes a non-functional alpha subunit that comprises 50% of the transcripts in normal human skeletal muscle, but its functional significance remains undetermined. In an effort to search for a potential therapy, we screened off-label effects of 960 bioactive chemical compounds and found that tannic acid ameliorates the aberrant splicing due to IVS3-8G>A but without altering the expression of hnRNP H. Therefore, we searched for another splicing trans-factor. We found that the polypyrimidine tract binding protein (PTB) binds close to the 3' end of CHRNA1 intron 3, that PTB induces skipping of exon P3A and that tannic acid increases the expression of PTB in a dose-dependent manner. Deletion assays of the PTB promoter region revealed that the tannic acid-responsive element is between positions -232 and -74 from the translation initiation site. These observations open the door to the discovery of novel therapies based on PTB overexpression and to detecting possible untoward effects of the overexpression.
Collapse
Affiliation(s)
- Yang Bian
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | | | | | | | | | | | | |
Collapse
|