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da Silva AM, Yevdokimova V, Benoit YD. Sam68 is a druggable vulnerability point in cancer stem cells. Cancer Metastasis Rev 2024; 43:441-456. [PMID: 37792222 PMCID: PMC11016129 DOI: 10.1007/s10555-023-10145-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/27/2023] [Indexed: 10/05/2023]
Abstract
Sam68 (Src associated in mitosis of 68 kDa) is an RNA-binding and multifunctional protein extensively characterized in numerous cellular functions, such as RNA processing, cell cycle regulation, kinase- and growth factor signaling. Recent investigations highlighted Sam68 as a primary target of a class of reverse-turn peptidomimetic drugs, initially developed as inhibitors of Wnt/β-catenin mediated transcription. Further investigations on such compounds revealed their capacity to selectively eliminate cancer stem cell (CSC) activity upon engaging Sam68. This work highlighted previously unappreciated roles for Sam68 in the maintenance of neoplastic self-renewal and tumor-initiating functions. Here, we discuss the implication of Sam68 in tumorigenesis, where central findings support its contribution to chromatin regulation processes essential to CSCs. We also review advances in CSC-targeting drug discovery aiming to modulate Sam68 cellular distribution and protein-protein interactions. Ultimately, Sam68 constitutes a vulnerability point of CSCs and an attractive therapeutic target to impede neoplastic stemness in human tumors.
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Affiliation(s)
- Amanda Mendes da Silva
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Veronika Yevdokimova
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Yannick D Benoit
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada.
- School of Pharmaceutical Sciences, Faculty of Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada.
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Gowd V, Kass JD, Sarkar N, Ramakrishnan P. Role of Sam68 as an adaptor protein in inflammatory signaling. Cell Mol Life Sci 2024; 81:89. [PMID: 38351330 PMCID: PMC10864426 DOI: 10.1007/s00018-023-05108-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 11/25/2023] [Accepted: 12/25/2023] [Indexed: 02/16/2024]
Abstract
Sam68 is a ubiquitously expressed KH-domain containing RNA-binding protein highly studied for its involvement in regulating multiple steps of RNA metabolism. Sam68 also contains multiple protein-protein interaction regions such as proline-rich regions, tyrosine phosphorylation sites, and arginine methylation sites, all of which facilitate its participation as an adaptor protein in multiple signaling pathways, likely independent of its RNA-binding role. This review focuses on providing a comprehensive report on the adaptor roles of Sam68 in inflammatory signaling and inflammatory diseases. The insights presented here have the potential to open new avenues in inflammation research and justify targeting Sam68 to control aberrant inflammatory responses.
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Affiliation(s)
- Vemana Gowd
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 6526, Wolstein Research Building, 2103 Cornell Road, Cleveland, OH, 44106, USA
| | - Joseph D'Amato Kass
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 6526, Wolstein Research Building, 2103 Cornell Road, Cleveland, OH, 44106, USA
| | - Nandini Sarkar
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 6526, Wolstein Research Building, 2103 Cornell Road, Cleveland, OH, 44106, USA
| | - Parameswaran Ramakrishnan
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 6526, Wolstein Research Building, 2103 Cornell Road, Cleveland, OH, 44106, USA.
- The Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
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3
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Verdile V, Palombo R, Ferrante G, Ferri A, Amadio S, Volonté C, Paronetto MP. Dysregulation of alternative splicing underlies synaptic defects in familial amyotrophic lateral sclerosis. Prog Neurobiol 2023; 231:102529. [PMID: 37739207 DOI: 10.1016/j.pneurobio.2023.102529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 09/11/2023] [Accepted: 09/17/2023] [Indexed: 09/24/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease characterized by the degeneration of upper and lower motor neurons, progressive wasting and paralysis of voluntary muscles. A hallmark of ALS is the frequent nuclear loss and cytoplasmic accumulation of RNA binding proteins (RBPs) in motor neurons (MN), which leads to aberrant alternative splicing regulation. However, whether altered splicing patterns are also present in familial models of ALS without mutations in RBP-encoding genes has not been investigated yet. Herein, we found that altered splicing of synaptic genes is a common trait of familial ALS MNs. Similar deregulation was also observed in hSOD1G93A MN-like cells. In silico analysis identified the potential regulators of these pre-mRNAs, including the RBP Sam68. Immunofluorescence analysis and biochemical fractionation experiments revealed that Sam68 accumulates in the cytoplasmic insoluble ribonucleoprotein fraction of MN. Remarkably, the synaptic splicing events deregulated in ALS MNs were also affected in Sam68-/- spinal cords. Recombinant expression of Sam68 protein was sufficient to rescue these splicing changes in ALS hSOD1G93A MN-like cells. Hence, our study highlights an aberrant function of Sam68, which leads to splicing changes in synaptic genes and may contribute to the MN phenotype that characterizes ALS.
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Affiliation(s)
- Veronica Verdile
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro de Bosis 6, 00135 Rome, Italy; Division of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Ramona Palombo
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro de Bosis 6, 00135 Rome, Italy
| | - Gabriele Ferrante
- Division of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Alberto Ferri
- Division of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, Rome 00143, Italy; National Research Council (CNR), Institute of Translational Pharmacology (IFT), Rome, Italy
| | - Susanna Amadio
- Division of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Cinzia Volonté
- Division of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, Rome 00143, Italy; National Research Council (CNR), Institute for Systems Analysis and Computer Science (IASI), Rome, Italy
| | - Maria Paola Paronetto
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro de Bosis 6, 00135 Rome, Italy; Division of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 64, Rome 00143, Italy.
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Liu X, Zheng Q, Wang K, Luo J, Wang Z, Li H, Liu Z, Dong N, Shi J. Sam68 promotes osteogenic differentiation of aortic valvular interstitial cells by TNF-α/STAT3/autophagy axis. J Cell Commun Signal 2023; 17:863-879. [PMID: 36847917 PMCID: PMC10409708 DOI: 10.1007/s12079-023-00733-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 02/10/2023] [Indexed: 03/01/2023] Open
Abstract
Calcified aortic valve disease (CAVD) is a major non-rheumatic heart valve disease in the world, with a high mortality rate and without suitable pharmaceutical therapy due to its complex mechanisms. Src-associated in mitosis 68-KD (Sam68), an RNA binding protein, has been reported as a signaling adaptor in numerous signaling pathways (Huot in Mol Cell Biol, 29(7), 1933-1943, 2009), particularly in inflammatory signaling pathways. The effects of Sam68 on the osteogenic differentiation process of hVICs and its regulation on signal transducer and activator of transcription 3 (STAT3) signaling pathway have been investigated in this study. Human aortic valve samples detection found that Sam68 expression was up-regulated in human calcific aortic valves. We used tumor necrosis factor α (TNF-α) as an activator for osteogenic differentiation in vitro and the result indicated that Sam68 was highly expressed after TNF-α stimulation. Overexpression of Sam68 promoted osteogenic differentiation of hVICs while Sam68 knockdown reversed this effect. Sam68 interaction with STAT3 was predicted by using String database and was verified in this study. Sam68 knockdown reduced phosphorylation of STAT3 activated by TNF-α and the downstream gene expression, which further influenced autophagy flux in hVICs. STAT3 knockdown alleviated the osteogenic differentiation and calcium deposition promoted by Sam68 overexpression. In conclusion, Sam68 interacts with STAT3 and participates in its phosphorylation to promote osteogenic differentiation of hVICs to induce valve calcification. Thus, Sam68 may be a new therapeutic target for CAVD. Regulatory of Sam68 in TNF-α/STAT3/Autophagy Axis in promoting osteogenesis of hVICs.
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Affiliation(s)
- Xing Liu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Qiang Zheng
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Kan Wang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Jinjing Luo
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Zhijie Wang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Huadong Li
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Zongtao Liu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Nianguo Dong
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Jiawei Shi
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
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Khudhair MK, Mohammed NI, Zabibah RS. Validating Sam68 expression and protein level in breast cancer. J Med Life 2023; 16:1136-1139. [PMID: 37900073 PMCID: PMC10600683 DOI: 10.25122/jml-2022-0229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 05/29/2023] [Indexed: 10/31/2023] Open
Abstract
Breast carcinoma ranks as the second most common cancer among women worldwide. Despite significant therapeutic advancements, approximately 25% of breast carcinoma cases have resistance to current treatment modalities, posing a significant challenge for patient management. This study aimed to investigate the role of Sam68 mRNA and its protein in promoting oncogenesis and breast cancer progression. Sam68 protein levels were assessed in tissue samples using an Enzyme-Linked Immunosorbent Assay kit from Sun Long Biotech. Whole RNA was isolated from malignant breast tissue samples obtained from patients. The RNA concentration was determined using an Eppendorf photometer, yielding an average concentration of 62.1±10.07 ng/µl. The purity of the isolated RNA was evaluated by measuring the A260/A280 ratio (1.9±0.07) and the A260/A230 ratio (1.7±0.3). The results indicated a significant upregulation of Sam68 mRNA expression in breast cancer tissues, supporting the findings from previous studies and indicating the correlation between altered Sam68 expression and the development of breast carcinoma, highlighting the potential significance of Sam68 in the pathogenesis of the disease. Estimating Sam68 in the blood may serve as a potential biomarker for assessing the malignant grade and metastatic spread of breast carcinoma cells.
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Affiliation(s)
- Muneer Kadhum Khudhair
- Department of Laboratory Investigation, Faculty of Science, University of Kufa, Kufa, Iraq
| | - Noaman Ibadi Mohammed
- Department of Physiology, Faculty of Veterinary Medicine, University of Kufa, Kufa, Iraq
| | - Rahman Sahib Zabibah
- Medical Laboratory Technology Department, College of Medicine, Islamic University, Najaf, Iraq
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Nadal M, Anton R, Dorca‐Arévalo J, Estébanez‐Perpiñá E, Tizzano EF, Fuentes‐Prior P. Structure and function analysis of Sam68 and hnRNP A1 synergy in the exclusion of exon 7 from SMN2 transcripts. Protein Sci 2023; 32:e4553. [PMID: 36560896 PMCID: PMC10031812 DOI: 10.1002/pro.4553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 12/13/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022]
Abstract
Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by the absence of a functional copy of the Survival of Motor Neuron 1 gene (SMN1). The nearly identical paralog, SMN2, cannot compensate for the loss of SMN1 because exon 7 is aberrantly skipped from most SMN2 transcripts, a process mediated by synergistic activities of Src-associated during mitosis, 68 kDa (Sam68/KHDRBS1) and heterogeneous nuclear ribonucleoprotein (hnRNP) A1. This results in the production of a truncated, nonfunctional protein that is rapidly degraded. Here, we present several crystal structures of Sam68 RNA-binding domain (RBD). Sam68-RBD forms stable symmetric homodimers by antiparallel association of helices α3 from two monomers. However, the details of domain organization and the dimerization interface differ significantly from previously characterized homologs. We demonstrate that Sam68 and hnRNP A1 can simultaneously bind proximal motifs within the central region of SMN2 (ex7). Furthermore, we show that the RNA-binding pockets of the two proteins are close to each other in their heterodimeric complex and identify contact residues using crosslinking-mass spectrometry. We present a model of the ternary Sam68·SMN2 (ex7)·hnRNP A1 complex that reconciles all available information on SMN1/2 splicing. Our findings have important implications for the etiology of SMA and open new avenues for the design of novel therapeutics to treat splicing diseases.
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Affiliation(s)
- Marta Nadal
- Molecular Bases of DiseaseBiomedical Research Institute Sant Pau (IIB Sant Pau)BarcelonaSpain
| | - Rosa Anton
- Molecular Bases of DiseaseBiomedical Research Institute Sant Pau (IIB Sant Pau)BarcelonaSpain
| | - Jonatan Dorca‐Arévalo
- Molecular Bases of DiseaseBiomedical Research Institute Sant Pau (IIB Sant Pau)BarcelonaSpain
- Present address:
Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, Campus of BellvitgeHospitalet de Llobregat, University of BarcelonaBarcelonaSpain
| | - Eva Estébanez‐Perpiñá
- Structural Biology of Nuclear Receptors, Department of Biochemistry and Molecular Biomedicine, Faculty of BiologyInstitute of Biomedicine (IBUB) of the University of Barcelona (UB)BarcelonaSpain
| | - Eduardo F. Tizzano
- Medicine Genetics GroupVall d'Hebron Research Institute (VHIR)BarcelonaSpain
- Department of Clinical and Molecular GeneticsHospital Vall d'HebronBarcelonaSpain
| | - Pablo Fuentes‐Prior
- Molecular Bases of DiseaseBiomedical Research Institute Sant Pau (IIB Sant Pau)BarcelonaSpain
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Adinolfi A, Di Sante G, Rivignani Vaccari L, Tredicine M, Ria F, Bonvissuto D, Corvino V, Sette C, Geloso MC. Regionally restricted modulation of Sam68 expression and Arhgef9 alternative splicing in the hippocampus of a murine model of multiple sclerosis. Front Mol Neurosci 2023; 15:1073627. [PMID: 36710925 PMCID: PMC9878567 DOI: 10.3389/fnmol.2022.1073627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/21/2022] [Indexed: 01/15/2023] Open
Abstract
Multiple sclerosis (MS) and its preclinical models are characterized by marked changes in neuroplasticity, including excitatory/inhibitory imbalance and synaptic dysfunction that are believed to underlie the progressive cognitive impairment (CI), which represents a significant clinical hallmark of the disease. In this study, we investigated several parameters of neuroplasticity in the hippocampus of the experimental autoimmune encephalomyelitis (EAE) SJL/J mouse model, characterized by rostral inflammatory and demyelinating lesions similar to Relapsing-Remitting MS. By combining morphological and molecular analyses, we found that the hippocampus undergoes extensive inflammation in EAE-mice, more pronounced in the CA3 and dentate gyrus (DG) subfields than in the CA1, associated with changes in GABAergic circuitry, as indicated by the increased expression of the interneuron marker Parvalbumin selectively in CA3. By laser-microdissection, we investigated the impact of EAE on the alternative splicing of Arhgef9, a gene encoding a post-synaptic protein playing an essential role in GABAergic synapses and whose mutations have been related to CI and epilepsy. Our results indicate that EAE induces a specific increase in inclusion of the alternative exon 11a only in the CA3 and DG subfields, in line with the higher local levels of inflammation. Consistently, we found a region-specific downregulation of Sam68, a splicing-factor that represses this splicing event. Collectively, our findings confirm a regionalized distribution of inflammation in the hippocampus of EAE-mice. Moreover, since neuronal circuit rearrangement and dynamic remodeling of structural components of the synapse are key processes that contribute to neuroplasticity, our study suggests potential new molecular players involved in EAE-induced hippocampal dysfunction.
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Affiliation(s)
- Annalisa Adinolfi
- Section of Human Anatomy, Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Gabriele Di Sante
- Section of Human, Clinic and Forensic Anatomy, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Luca Rivignani Vaccari
- Section of Human Anatomy, Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Maria Tredicine
- Section of General Pathology, Department of Translational Medicine and Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Francesco Ria
- Section of General Pathology, Department of Translational Medicine and Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Davide Bonvissuto
- Section of Human Anatomy, Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Valentina Corvino
- Section of Human Anatomy, Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Claudio Sette
- Section of Human Anatomy, Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy,GSTEP-Organoids Core Facility, Fondazione Policlinico Agostino Gemelli IRCCS, Rome, Italy,*Correspondence: Claudio Sette, ✉
| | - Maria Concetta Geloso
- Section of Human Anatomy, Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy,Maria Concetta Geloso, ✉
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Boustanai I, Raanani H, Aizer A, Orvieto R, Elizur SE. Granulosa Cell Dysfunction Is Associated With Diminished Ovarian Response in FMR1 Premutation Carriers. J Clin Endocrinol Metab 2022; 107:3000-3009. [PMID: 36112470 DOI: 10.1210/clinem/dgac536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Indexed: 02/13/2023]
Abstract
CONTEXT FMR1 premutation (PM) carriers are at increased risk of ovarian impairment resulting in diminished ovarian response (DOR) to exogenous follicle-stimulating hormone (FSH) stimulation. Expanded CGG repeat transcript and RAN-associated protein (FMRpolyG) have been shown to accumulate in cellular aggregates and sequester proteins, thus impairing their function. Sam68 is a multifunctional RNA-binding protein highly expressed in the gonads involved in FSH receptor (FSHR) transcript maturation during FSH-dependent follicular development. OBJECTIVE The present study examined a possible pathophysiological explanation for DOR to exogenous FSH stimulation in FMR1 PM carriers. METHODS We used both a human granulosa cell (GC) line model and human GCs from FMR1 PM carriers to evaluate whether Sam68 is sequestered with expanded CGG repeat transcript. RESULTS We show that Sam68 is sequestered in GCs, most likely by interaction with the expanded CGG repeat transcript. The sequestration may lead to reduced levels of free Sam68 available for FHSR precursor transcript processing, causing dysregulation of FSHR transcript maturation, and a consequent decrease in FSHR protein levels. CONCLUSION Sam68 sequestration may underlie the diminished ovarian response to FSH stimulation in FMR1 PM carriers.
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Affiliation(s)
- Ilana Boustanai
- Sheba Medical Center Hospital-Tel Hashomer, Ramat-Gan 52621, Israel
| | - Hila Raanani
- Sheba Medical Center Hospital-Tel Hashomer, Ramat-Gan 52621, Israel
| | - Adva Aizer
- Sheba Medical Center Hospital-Tel Hashomer, Ramat-Gan 52621, Israel
| | - Raoul Orvieto
- Sheba Medical Center Hospital-Tel Hashomer, Ramat-Gan 52621, Israel
- Sackler Faculty of Medicine Tel-Aviv University, Tel-Aviv 6997801, Israel
| | - Shai E Elizur
- Sheba Medical Center Hospital-Tel Hashomer, Ramat-Gan 52621, Israel
- Sackler Faculty of Medicine Tel-Aviv University, Tel-Aviv 6997801, Israel
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Vilariño-García T, Guadix P, Dorado-Silva M, Sánchez-Martín P, Pérez-Pérez A, Sánchez-Margalet V. Decreased Expression of Sam68 Is Associated with Insulin Resistance in Granulosa Cells from PCOS Patients. Cells 2022; 11:cells11182821. [PMID: 36139396 PMCID: PMC9496917 DOI: 10.3390/cells11182821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 09/01/2022] [Accepted: 09/02/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Polycystic ovary syndrome (PCOS) is a complex metabolic disorder associated with ovulatory dysfunction, hyperandrogenism, obesity, and insulin resistance, which leads to subfertility. PCOS is the most frequent metabolic disorder in women and the major cause of infertility. Susceptibility to developing PCOS is determined by a complex interaction between environmental and genetic factors. Although different mechanisms have been proposed to explain PCOS manifestations, defects in insulin actions or in the insulin signaling pathways are central in the pathogenesis of the syndrome. However, the mechanisms (molecular players and signaling pathways) underlying its primary origin still remain an unsolved issue. Current research is increasingly focusing on the discovery of novel biomarkers to further elucidate the complex pathophysiology of PCOS. Sam68, an RNA-binding protein, is recruited to insulin signaling, mediating different insulin actions. We aimed to investigate the role of Sam68 in insulin signaling and the possible implications of Sam68 in the insulin resistance in PCOS. MATERIALS AND METHODS Granulosa cells were taken from women with PCOS (n = 25) and healthy donors (n = 25) and, within the age range of 20 to 42 years, from GINEMED, Assisted Reproduction Centre, Seville, Spain. The Sam68 expression level was analyzed both by qPCR and immunoblot. Statistical significance was assessed by one-way ANOVA, followed by a post-hoc test. A p value of < 0.05 was considered statistically significant. RESULTS We found that insulin stimulation increases the phosphorylation and expression level of Sam68 in granulosa cells from normal donors. The downregulation of Sam68 expression resulted in a lower activation of both the MAPK and the PI3K pathways in response to insulin. Moreover, the granulosa cells from the women with PCOS presented a lower expression of Sam68, as well as insulin receptor and insulin receptor substrate-1 (IRS-1). In these cells, the overexpression of Sam68 resulted in an increased activation of both the MAPK and the PI3K pathways in response to insulin. CONCLUSIONS These results suggest the participation of Sam68 in insulin receptor signaling, mediating the insulin effect in granulosa cells, and they suggest the possible role of Sam68 in the insulin resistance of PCOS.
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Affiliation(s)
- Teresa Vilariño-García
- Department of Medical Biochemistry and Molecular Biology and Immunology, Virgen Macarena University Hospital, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Pilar Guadix
- Obstetrics and Gynecology Department, Virgen Macarena University Hospital, School of Medicine, University of Seville, 41009 Seville, Spain
| | | | | | - Antonio Pérez-Pérez
- Department of Medical Biochemistry and Molecular Biology and Immunology, Virgen Macarena University Hospital, School of Medicine, University of Seville, 41009 Seville, Spain
- Correspondence: (A.P.-P.); (V.S.-M.); Tel.: +95-4559-850 (A.P.-P.)
| | - Víctor Sánchez-Margalet
- Department of Medical Biochemistry and Molecular Biology and Immunology, Virgen Macarena University Hospital, School of Medicine, University of Seville, 41009 Seville, Spain
- Correspondence: (A.P.-P.); (V.S.-M.); Tel.: +95-4559-850 (A.P.-P.)
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Zhang JY, Du Y, Gong LP, Shao YT, Pan LJ, Feng ZY, Pan YH, Huang JT, Wen JY, Sun LP, Chen GF, Chen JN, Shao CK. ebv-circRPMS1 promotes the progression of EBV-associated gastric carcinoma via Sam68-dependent activation of METTL3. Cancer Lett 2022; 535:215646. [PMID: 35304258 DOI: 10.1016/j.canlet.2022.215646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/12/2022] [Accepted: 03/13/2022] [Indexed: 12/12/2022]
Abstract
Epstein-Barr virus (EBV) is a tumor virus that is associated with a variety of neoplasms, including EBV-associated gastric carcinoma (EBVaGC). Recently, EBV was reported to generate various circular RNAs (circRNAs). CircRNAs are important regulators of tumorigenesis by modulating the malignant behaviors of tumor cells. However, to date, the functions of ebv-circRNAs in EBVaGC remain poorly understood. In the present study, we observed high ebv-circRPMS1 expression in EBVaGC and showed that ebv-circRPMS1 promoted the proliferation, migration, and invasion and inhibited the apoptosis of EBVaGC cells. In addition, METTL3 was upregulated in GC cells overexpressing ebv-circRPMS1. Mechanistically, ebv-circRPMS1 bound to Sam68 to facilitate its physical interaction with the METTL3 promotor, resulting in the transactivation of METTL3 and cancer progression. In clinical EBVaGC samples, ebv-circRPMS1 was associated with distant metastasis and a poor prognosis. Based on these findings, ebv-circRPMS1 contributed to EBVaGC progression by recruiting Sam68 to the METTL3 promoter to induce METTL3 expression. ebv-circRPMS1, Sam68, and METTL3 might serve as therapeutic targets for EBVaGC.
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Affiliation(s)
- Jing-Yue Zhang
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Yu Du
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Li-Ping Gong
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Yi-Ting Shao
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, 510055, China
| | - Li-Jie Pan
- Vaccine Research of Sun Yat-sen University, Guangzhou, 510630, China
| | - Zhi-Ying Feng
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Yu-Hang Pan
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Jun-Ting Huang
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China; The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510182, China
| | - Jing-Yun Wen
- Department of Medical Oncology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Li-Ping Sun
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Gao-Feng Chen
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China
| | - Jian-Ning Chen
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China.
| | - Chun-Kui Shao
- Department of Pathology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510630, China.
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11
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Qiao A, Ma W, Deng J, Zhou J, Han C, Zhang E, Boriboun C, Xu S, Zhang C, Jie C, Kim JA, Habegger KM, Qiu H, Zhao TC, Zhang J, Qin G. Ablation of Sam68 in adult mice increases thermogenesis and energy expenditure. FASEB J 2021; 35:e21772. [PMID: 34252225 DOI: 10.1096/fj.202100021r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 05/27/2021] [Accepted: 06/17/2021] [Indexed: 12/18/2022]
Abstract
Genetic deletion of Src associated in mitosis of 68kDa (Sam68), a pleiotropic adaptor protein prevents high-fat diet-induced weight gain and insulin resistance. To clarify the role of Sam68 in energy metabolism in the adult stage, we generated an inducible Sam68 knockout mice. Knockout of Sam68 was induced at the age of 7-10 weeks, and then we examined the metabolic profiles of the mice. Sam68 knockout mice gained less body weight over time and at 34 or 36 weeks old, had smaller fat mass without changes in food intake and absorption efficiency. Deletion of Sam68 in mice elevated thermogenesis, increased energy expenditure, and attenuated core-temperature drop during acute cold exposure. Furthermore, we examined younger Sam68 knockout mice at 11 weeks old before their body weights deviate, and confirmed increased energy expenditure and thermogenic gene program. Thus, Sam68 is essential for the control of adipose thermogenesis and energy homeostasis in the adult.
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Affiliation(s)
- Aijun Qiao
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Wenxia Ma
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jianxin Deng
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Junlan Zhou
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Chaoshan Han
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Eric Zhang
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chan Boriboun
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Shiyue Xu
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chunxiang Zhang
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chunfa Jie
- Department of Biochemistry and Nutrition, Des Moines University College of Osteopathic Medicine, Des Moines, IA, USA
| | - Jeong-A Kim
- Department of Medicine-Endocrinology, Diabetes & Metabolism, Comprehensive Diabetes Center, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kirk M Habegger
- Department of Medicine-Endocrinology, Diabetes & Metabolism, Comprehensive Diabetes Center, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hongyu Qiu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA, USA
| | - Ting C Zhao
- Department of Surgery, Boston University Medical School, Roger Williams Medical Center, Providence, RI, USA
| | - Jianyi Zhang
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Gangjian Qin
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA.,Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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12
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Bordonaro M. Hypothesis: Sam68 and Pygo2 mediate cell type-specific effects of the modulation of CBP-Wnt and p300-Wnt activities in Colorectal Cancer Cells. J Cancer 2021; 12:5046-5052. [PMID: 34234873 PMCID: PMC8247382 DOI: 10.7150/jca.59726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 06/07/2021] [Indexed: 11/08/2022] Open
Abstract
The preventive activity of dietary fiber against colorectal cancer (CRC) may be in part mediated by the fermentation product of fiber, butyrate, a histone deacetylase inhibitor (HDACi) that induces CRC cell growth arrest and apoptosis. This action of butyrate, and other HDACis, is in part due to the hyperactivation of the deregulated Wnt activity found in the relevant CRC cell lines. The histone acetylases CBP and p300 interact with beta-catenin; and the relative levels of CBP-Wnt vs. p300-Wnt activity influences CRC cell physiology. It has previously been observed that there are cell type-specific differences in how cotreatment with butyrate and ICG-001, an agent that blocks CBP-Wnt activity allowing for p300-Wnt activity, affects CRC cell physiology. These differences may have clinical significance in dealing with treatment of CRC patients with ICG-001-like agents. Sam68 is a factor differentially expressed in cancer cells, with higher expression in cancer cell lines that have cancer stem cell (CSC)-like properties. Sam68 expression sensitizes cancer cells to ICG-001 treatment, as ICG-001 enhances nuclear localization of Sam68, where binding between Sam68 and CBP diminishes CBP-beta-catenin binding and thus CBP-Wnt activity. Pygo2 is a chromatin effector involved with Wnt signaling that is differentially acetylated by CBP and p300; thus CBP-mediated acetylation localized Pygo2 to the nucleus where it functions in transcriptional activation, while p300-mediated acetylation localizes Pygo2 to the cytoplasm. This paper proposes the hypothesis that Sam68 and Pygo2 are responsible for cell type-specific response of CRC cell lines cotreated with ICG-001 and butyrate as well as other HDACis. Further, experiments are proposed to evaluate this hypothesis and consider possible expected results that could be obtained from such studies.
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Affiliation(s)
- Michael Bordonaro
- Department of Medical Education, Geisinger Commonwealth School of Medicine, 525 Pine Street, Scranton, PA 18509, USA
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13
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Chen X, Zhang L, Yuan M, Kuang Z, Zou Y, Tang T, Zhang W, Hu X, Xia T, Cao T, Jia H. Sam68 Promotes the Progression of Human Breast Cancer through inducing Activation of EphA3. Curr Cancer Drug Targets 2021; 20:76-83. [PMID: 31433759 DOI: 10.2174/1568009619666190718124541] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 04/08/2019] [Accepted: 06/28/2019] [Indexed: 12/26/2022]
Abstract
BACKGROUND Src associated with mitosis of 68 kDa (Sam68), is often highly expressed in human cancers. Overexpression of Sam68 has been shown to be correlated with poor survival prognosis in some cancer patients. However, little is known whether Sam68 plays a role in promoting metastasis in breast cancer. MATERIALS AND METHODS The expression of Sam68 protein in breast cancer tissue was detected by immunohistochemistry. Trans-well assay, wound-healing, real-time PCR and Western blotting analysis were used to detect the effect of Sam68 on promoting EMT or metastasis of breast cancer. Next-generation RNA sequencing was used to analyze genes that may be regulated by Sam68. RESULTS Sam68 plays a positive role in promoting breast cancer metastasis. Sam68 was found to be overexpressed in breast cancer along with lymph node metastasis. MMP-9 was also found to be overexpressed in breast cancer tissue and was correlated to the expression of Sam68 (P<0.01). Xenograft in NOD/SCID mice and in vitro experiments confirmed that the invasion and metastatic ability of breast cancer cells were regulated by Sam68. And EPHA3 could be up-regulated by Sam68 in breast cancer. CONCLUSION High expression of Sam68 participates in breast cancer metastasis by up-regulating the EPHA3 gene.
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Affiliation(s)
- Xinxin Chen
- Department of Breast Surgery, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Lehong Zhang
- Department of Breast Surgery, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Min Yuan
- Department of Breast Surgery, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Ziqiao Kuang
- Department of Breast Surgery, Huadu District People's Hospital of Guangzhou, Guangdong, China
| | - Ying Zou
- Department of Environmental Health Sciences, University at Albany, State University of New York, Rensselaer, NY, United States
| | - Tian Tang
- Department of Pathology, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Wangjian Zhang
- Department of Environmental Health Sciences, University at Albany, State University of New York, Rensselaer, NY, United States
| | - Xiaowu Hu
- Department of Breast Surgery, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Ting Xia
- Department of Breast Surgery, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Tengfei Cao
- Department of Breast Surgery, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Haixia Jia
- Department of Breast Surgery, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
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Farini D, Cesari E, Weatheritt RJ, La Sala G, Naro C, Pagliarini V, Bonvissuto D, Medici V, Guerra M, Di Pietro C, Rizzo FR, Musella A, Carola V, Centonze D, Blencowe BJ, Marazziti D, Sette C. A Dynamic Splicing Program Ensures Proper Synaptic Connections in the Developing Cerebellum. Cell Rep 2021; 31:107703. [PMID: 32492419 DOI: 10.1016/j.celrep.2020.107703] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 03/13/2020] [Accepted: 05/07/2020] [Indexed: 12/14/2022] Open
Abstract
Tight coordination of gene expression in the developing cerebellum is crucial for establishment of neuronal circuits governing motor and cognitive function. However, transcriptional changes alone do not explain all of the switches underlying neuronal differentiation. Here we unveiled a widespread and highly dynamic splicing program that affects synaptic genes in cerebellar neurons. The motifs enriched in modulated exons implicated the splicing factor Sam68 as a regulator of this program. Sam68 controls splicing of exons with weak branchpoints by directly binding near the 3' splice site and competing with U2AF recruitment. Ablation of Sam68 disrupts splicing regulation of synaptic genes associated with neurodevelopmental diseases and impairs synaptic connections and firing of Purkinje cells, resulting in motor coordination defects, ataxia, and abnormal social behavior. These findings uncover an unexpectedly dynamic splicing regulatory network that shapes the synapse in early life and establishes motor and cognitive circuitry in the developing cerebellum.
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Affiliation(s)
- Donatella Farini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy; Fondazione Santa Lucia, IRCCS, Rome, Italy
| | - Eleonora Cesari
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Rome, Italy; Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Robert J Weatheritt
- Donnelly Centre and Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada; EMBL Australia, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
| | - Gina La Sala
- Institute of Cell Biology and Neurobiology, CNR, Monterotondo, Rome, Italy
| | - Chiara Naro
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Rome, Italy; Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Vittoria Pagliarini
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Rome, Italy; Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Davide Bonvissuto
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Rome, Italy
| | - Vanessa Medici
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy; Fondazione Santa Lucia, IRCCS, Rome, Italy
| | - Marika Guerra
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Rome, Italy; Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Chiara Di Pietro
- Institute of Cell Biology and Neurobiology, CNR, Monterotondo, Rome, Italy
| | - Francesca Romana Rizzo
- Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy; San Raffaele Pisana and University San Raffaele, IRCCS, Rome, Italy
| | | | - Valeria Carola
- Fondazione Santa Lucia, IRCCS, Rome, Italy; Department of Dynamic and Clinical Psychology, University of Rome Sapienza, Rome, Italy
| | - Diego Centonze
- Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy; Unit of Neurology, IRCCS Neuromed, Pozzilli, Isernia, Italy
| | - Benjamin J Blencowe
- Donnelly Centre and Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Daniela Marazziti
- Institute of Cell Biology and Neurobiology, CNR, Monterotondo, Rome, Italy
| | - Claudio Sette
- Fondazione Santa Lucia, IRCCS, Rome, Italy; Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Rome, Italy.
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15
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Vilariño-García T, Pérez-Pérez A, Santamaría-López E, Prados N, Fernández-Sánchez M, Sánchez-Margalet V. Sam68 mediates leptin signaling and action in human granulosa cells: possible role in leptin resistance in PCOS. Endocr Connect 2020; 9:479-488. [PMID: 32375121 PMCID: PMC7354740 DOI: 10.1530/ec-20-0062] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 05/06/2020] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Polycystic ovary syndrome (PCOS) is a complex metabolic disorder associated with ovulatory dysfunction, hyperandrogenism, obesity, and insulin resistance, that leads to subfertility. Sam68 is an RNA-binding protein with signaling functions that is ubiquitously expressed, including gonads. Sam68 is recruited to leptin signaling, mediating different leptin actions. OBJECTIVE We aimed to investigate the role of Sam68 in leptin signaling, mediating the effect on aromatase expression in granulosa cells and the posible implication of Sam68 in the leptin resistance in PCOS. MATERIALS AND METHODS Granulosa cells were from healthy donors (n = 25) and women with PCOS (n = 25), within the age range of 20 to 40 years, from Valencian Infertility Institute (IVI), Seville, Spain. Sam68 expression was inhibited by siRNA method and overexpressed by expression vector. Expression level was analysed by qPCR and immunoblot. Statistical significance was assessed by ANOVA followed by different post-hoc tests. A P value of <0.05 was considered statistically significant. RESULTS We have found that leptin stimulation increases phosphorylation and expression level of Sam68 and aromatase in granulosa cells from normal donors. Downregulation of Sam68 expression resulted in a lower activation of MAPK and PI3K pathways in response to leptin, whereas overexpression of Sam68 increased leptin stimulation of signaling, enhancing aromatase expression. Granulosa cells from women with PCOS presented lower expression of Sam68 and were resistant to the leptin effect on aromatase expression. CONCLUSIONS These results suggest the participation of Sam68 in leptin receptor signaling, mediating the leptin effect on aromatase expression in granulosa cells, and point to a new target in leptin resistance in PCOS.
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Affiliation(s)
- Teresa Vilariño-García
- Department of Medical Biochemistry, Molecular Biology and Immunology. Medical School, Virgen Macarena University Hospital, University of Seville, Seville, Spain
| | - Antonio Pérez-Pérez
- Department of Medical Biochemistry, Molecular Biology and Immunology. Medical School, Virgen Macarena University Hospital, University of Seville, Seville, Spain
| | | | | | | | - Víctor Sánchez-Margalet
- Department of Medical Biochemistry, Molecular Biology and Immunology. Medical School, Virgen Macarena University Hospital, University of Seville, Seville, Spain
- Correspondence should be addressed to V Sánchez-Margalet:
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Naro C, Pellegrini L, Jolly A, Farini D, Cesari E, Bielli P, de la Grange P, Sette C. Functional Interaction between U1snRNP and Sam68 Insures Proper 3' End Pre-mRNA Processing during Germ Cell Differentiation. Cell Rep 2020; 26:2929-2941.e5. [PMID: 30865884 DOI: 10.1016/j.celrep.2019.02.058] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 01/15/2019] [Accepted: 02/14/2019] [Indexed: 01/02/2023] Open
Abstract
Male germ cells express the widest repertoire of transcript variants in mammalian tissues. Nevertheless, factors and mechanisms underlying such pronounced diversity are largely unknown. The splicing regulator Sam68 is highly expressed in meiotic cells, and its ablation results in defective spermatogenesis. Herein, we uncover an extensive splicing program operated by Sam68 across meiosis, primarily characterized by alternative last exon (ALE) regulation in genes of functional relevance for spermatogenesis. Lack of Sam68 preferentially causes premature transcript termination at internal polyadenylation sites, a feature observed also upon depletion of the spliceosomal U1snRNP in somatic cells. Notably, Sam68-regulated ALEs are characterized by proximity between U1snRNP and Sam68 binding motifs. We demonstrate a physical association between Sam68 and U1snRNP and show that U1snRNP recruitment to Sam68-regulated ALEs is impaired in Sam68-/- germ cells. Thus, our study reveals an unexpected cooperation between Sam68 and U1snRNP that insures proper processing of transcripts essential for male fertility.
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Affiliation(s)
- Chiara Naro
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Hearth, 00168 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Livia Pellegrini
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Ariane Jolly
- GenoSplice Technology, iPEPS-ICM, Hôpital de la Pitié Salpêtrière, 75013 Paris, France
| | - Donatella Farini
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Eleonora Cesari
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Hearth, 00168 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Pamela Bielli
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Pierre de la Grange
- GenoSplice Technology, iPEPS-ICM, Hôpital de la Pitié Salpêtrière, 75013 Paris, France
| | - Claudio Sette
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Hearth, 00168 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy.
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17
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Vasileva E, Shuvalov O, Petukhov A, Fedorova O, Daks A, Nader R, Barlev N. KMT Set7/9 is a new regulator of Sam68 STAR-protein. Biochem Biophys Res Commun 2020; 525:1018-1024. [PMID: 32178870 DOI: 10.1016/j.bbrc.2020.03.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 03/03/2020] [Indexed: 12/12/2022]
Abstract
Lysine-specific methyltransferase Set7/9 (KMT7) belongs to the SET domain family of proteins. Besides the SET domain, Set7/9 also contains a so-called MORN (Membrane Occupation and Recognition Nexus) domain whose function in high eukaryotes is largely unknown. Set7/9 has been shown to specifically methylate both histones H1 and H3 as well as a number of non-histone substrates, including p53, E2F1, RelA, AR, and other important transcription factors. However, despite the ever growing list of potential substrates of Set7/9, the question of its substrate specificity is still debatable. To gain a better understanding of the Set7/9 substrate specificity and to clarify the importance of structural domains of Set7/9 for protein-protein interactions (PPIs) we determined interactomes for both MORN and SET domains of Set7/9 by pull-down assay coupled with mass-spectrometry. Importantly, we demonstrated that most of PPIs of Set7/9 are mediated via its MORN domain. The latter has preference towards positively charged amino acids that are often found in RNA-binding proteins. One of the Set7/9-interacting proteins was identified as Sam68, an RNA splicing protein with a KH (heterogeneous nuclear ribonucleoprotein K (hnRNP K) homology) domain. Importantly, the RG-rich domain of Sam68 that is also present in many splicing factors was found to interact with Set7/9. We revealed that Set7/9 not only co-immunoprecipitated with Sam68, but also methylated the latter on K208. Functionally, knockout of Set7/9 decreased the protein level of Sam68 in cells resulting in altered regulation of cell cycle and apoptosis. Finally, the bioinformatics analysis established a correlation between the high levels of Sam68/Set7/9 co-expression and better survival rates of patients with colon cancer.
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Affiliation(s)
- Elena Vasileva
- Institute of Cytology, Russian Academy of Sciences, 194064, Russian Federation
| | - Oleg Shuvalov
- Institute of Cytology, Russian Academy of Sciences, 194064, Russian Federation
| | - Alexey Petukhov
- Institute of Cytology, Russian Academy of Sciences, 194064, Russian Federation; Almazov National Medical Research Centre, Institute of Hematology, 197341, Russian Federation
| | - Olga Fedorova
- Institute of Cytology, Russian Academy of Sciences, 194064, Russian Federation
| | - Alexandra Daks
- Institute of Cytology, Russian Academy of Sciences, 194064, Russian Federation
| | - Rahimi Nader
- Department of Pathology & Laboratory Medicine, Boston University, 72 East Concord St., Boston, MA, 02118, USA
| | - Nickolai Barlev
- Institute of Cytology, Russian Academy of Sciences, 194064, Russian Federation; Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region, 141700, Russian Federation.
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18
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Han S, Xu S, Zhou J, Qiao A, Boriboun C, Ma W, Li H, Biyashev D, Yang L, Zhang E, Liu Q, Jiang S, Zhao TC, Krishnamurthy P, Zhang C, Richard S, Qiu H, Zhang J, Qin G. Sam68 impedes the recovery of arterial injury by augmenting inflammatory response. J Mol Cell Cardiol 2019; 137:82-92. [PMID: 31639388 DOI: 10.1016/j.yjmcc.2019.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/23/2019] [Accepted: 10/14/2019] [Indexed: 12/15/2022]
Abstract
OBJECTIVE The role of Src-associated-in-mitosis-68-kDa (Sam68) in cardiovascular biology has not been studied. A recent report suggests that Sam68 promotes TNF-α-induced NF-κB activation in fibroblasts. Here we sought to dissect the molecular mechanism by which Sam68 regulates NF-κB signaling and its functional significance in vascular injury. APPROACH AND RESULTS The endothelial denudation injury was induced in the carotid artery of Sam68-null (Sam68-/-) and WT mice. Sam68-/- mice displayed an accelerated re-endothelialization and attenuated neointima hyperplasia, which was associated with a reduced macrophage infiltration and lowered expression of pro-inflammatory cytokines in the injured vessels. Remarkably, the ameliorated vascular remodeling was recapitulated in WT mice after receiving transplantation of bone marrow (BM) from Sam68-/- mice, suggesting the effect was attributable to BM-derived inflammatory cells. In cultured Raw264.7 macrophages, knockdown of Sam68 resulted in a significant reduction in the TNF-α-induced expression of TNF-α, IL-1β, and IL-6 and in the level of nuclear phospho-p65, indicating attenuated NF-κB activation; and these results were confirmed in peritoneal and BM-derived macrophages of Sam68-/- vs. WT mice. Furthermore, co-immunoprecipitation and mass-spectrometry identified Filamin A (FLNA) as a novel Sam68-interacting protein upon TNF-α treatment. Loss- and gain-of-function experiments suggest that Sam68 and FLNA are mutually dependent for NF-κB activation and pro-inflammatory cytokine expression, and that the N-terminus of Sam68 is required for TRAF2-FLNA interaction. CONCLUSIONS Sam68 promotes pro-inflammatory response in injured arteries and impedes recovery by interacting with FLNA to stabilize TRAF2 on the cytoskeleton and consequently potentiate NF-κB signaling.
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Affiliation(s)
- Shuling Han
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Shiyue Xu
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Junlan Zhou
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Aijun Qiao
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Chan Boriboun
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Wenxia Ma
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Huadong Li
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Dauren Biyashev
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Liu Yang
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Eric Zhang
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Qinghua Liu
- Institute for Medical Biology and Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Sciences, South-Central University for Nationalities, Wuhan 430074, Hubei, China
| | - Shayi Jiang
- Department of Hematology, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai 20062, China
| | - Ting C Zhao
- Department of Surgery, Roger Williams Medical Center, Boston University Medical School, Providence, RI 02908, USA
| | - Prasanna Krishnamurthy
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Chunxiang Zhang
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Stéphane Richard
- Lady Davis Institute for Medical Research, McGill University, Montreal, Quebec, Canada
| | - Hongyu Qiu
- Center of Molecular and Translational Medicine, Institution of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA
| | - Jianyi Zhang
- Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Gangjian Qin
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Molecular Cardiology Program, Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Fu K, Sun X, Xia X, Hobbs RP, Guo Y, Coulombe PA, Wan F. Sam68 is required for the growth and survival of nonmelanoma skin cancer. Cancer Med 2019; 8:6106-6113. [PMID: 31436046 PMCID: PMC6792479 DOI: 10.1002/cam4.2513] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/07/2019] [Accepted: 08/11/2019] [Indexed: 12/20/2022] Open
Abstract
Although targeting DNA repair signaling pathways has emerged as a promising therapeutic for skin cancer, the relevance of DNA damage responses (DDR) in the development and survival of nonmelanoma skin cancer (NMSC), the most common type of skin cancer, remains obscure. Here, we report that Src-associated substrate during mitosis of 68 kDa (Sam68), an early signaling molecule in DDR, is elevated in skin tumor tissues derived from NMSC patients and skin lesions from Gli2-transgenic mice. Downregulation of Sam68 impacts the growth and survival of human tumor keratinocytes and genetic ablation of Sam68 delays the onset of basal cell carcinomas (BCC) in Gli2-transgenic mice. Moreover, Sam68 plays a critical role in DNA damage-induced DNA repair and nuclear factor kappa B (NF-κB) signaling pathways in keratinocytes, hence conferring keratinocyte sensitivity to DNA damaging agents. Together, our data reveal a novel function of Sam68 in regulating DDR in keratinocytes that is crucial for the growth and survival of NMSC.
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Affiliation(s)
- Kai Fu
- Institute of Molecular Precision Medicine and Hunan Key Laboratory of Molecular Precision Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Department of Oncology, Xiangya Hospital, Central South University, Changsha, Hunan, China.,Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Xin Sun
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,The Rockefeller University, New York, NY, USA
| | - Xue Xia
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Ryan P Hobbs
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Department of Dermatology, College of Medicine, Pennsylvania State University, Hershey, PA, USA
| | - Yajuan Guo
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Pierre A Coulombe
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Dermatology, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Oncology, Johns Hopkins University School of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD, USA.,Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Fengyi Wan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Department of Oncology, Johns Hopkins University School of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD, USA.,Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Medical Institutions, Baltimore, MD, USA.,W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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20
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Qin Y, Xun Z, Guo Y, Chen S, Zhu H. Sam68 Promotes Hepatitis C Virus Replication by Interaction with Stem-Loop 2 of Viral 5' Untranslated Region. J Virol 2019; 93:e00693-19. [PMID: 31068419 DOI: 10.1128/JVI.00693-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 12/12/2022] Open
Abstract
The Src-associated in mitosis 68-kDa (Sam68) protein is a highly conserved nuclear protein and is involved in a series of cellular processes, including transcription and signal transduction. Sam68 is comprised of 443 amino acids and contains an RGG box domain, a KH domain, and a tyrosine-rich domain. Its role in hepatitis C virus (HCV) replication is unknown. Here, we find that Sam68 promotes HCV replication without affecting viral translation. The RNA immunoprecipitation experiments show that the positive strand of HCV RNA interacts with Sam68. HCV infection triggers the translocation of the Sam68 protein from the nucleus to the cytoplasm, where it interacts with the HCV genome. Further study shows that the region of Sam68 spanning amino acids 1 to 157 is the pivotal domain to interact with the stem-loop 2 of the HCV 5' untranslated region (5' UTR) and is responsible for the enhancement of HCV replication. These data suggested that Sam68 may serve as a proviral factor of HCV to facilitate viral replication through interaction with the viral genome.IMPORTANCE Hepatitis C virus (HCV) is a member of the Flaviviridae family, and its infection causes chronic hepatitis, liver cirrhosis, and even hepatocellular carcinoma. No vaccine is available. Many host factors may be implicated in the pathogenesis of HCV-related diseases. This study discloses a new host factor that binds to the HCV 5' UTR and promotes HCV replication. Sam68 may play an important role in HCV-related diseases, and further investigation is highly encouraged to explore its specific actions in HCV pathogenesis.
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21
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Ravanidis S, Kattan FG, Doxakis E. Unraveling the Pathways to Neuronal Homeostasis and Disease: Mechanistic Insights into the Role of RNA-Binding Proteins and Associated Factors. Int J Mol Sci 2018; 19:ijms19082280. [PMID: 30081499 PMCID: PMC6121432 DOI: 10.3390/ijms19082280] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 07/26/2018] [Accepted: 07/31/2018] [Indexed: 12/13/2022] Open
Abstract
The timing, dosage and location of gene expression are fundamental determinants of brain architectural complexity. In neurons, this is, primarily, achieved by specific sets of trans-acting RNA-binding proteins (RBPs) and their associated factors that bind to specific cis elements throughout the RNA sequence to regulate splicing, polyadenylation, stability, transport and localized translation at both axons and dendrites. Not surprisingly, misregulation of RBP expression or disruption of its function due to mutations or sequestration into nuclear or cytoplasmic inclusions have been linked to the pathogenesis of several neuropsychiatric and neurodegenerative disorders such as fragile-X syndrome, autism spectrum disorders, spinal muscular atrophy, amyotrophic lateral sclerosis and frontotemporal dementia. This review discusses the roles of Pumilio, Staufen, IGF2BP, FMRP, Sam68, CPEB, NOVA, ELAVL, SMN, TDP43, FUS, TAF15, and TIA1/TIAR in RNA metabolism by analyzing their specific molecular and cellular function, the neurological symptoms associated with their perturbation, and their axodendritic transport/localization along with their target mRNAs as part of larger macromolecular complexes termed ribonucleoprotein (RNP) granules.
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Affiliation(s)
- Stylianos Ravanidis
- Basic Sciences Division I, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece.
| | - Fedon-Giasin Kattan
- Basic Sciences Division I, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece.
| | - Epaminondas Doxakis
- Basic Sciences Division I, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece.
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22
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Wang X, Yu H, Sun W, Kong J, Zhang L, Tang J, Wang J, Xu E, Lai M, Zhang H. The long non-coding RNA CYTOR drives colorectal cancer progression by interacting with NCL and Sam68. Mol Cancer 2018; 17:110. [PMID: 30064438 PMCID: PMC6069835 DOI: 10.1186/s12943-018-0860-7] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 07/20/2018] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Long non-coding RNAs (lncRNAs) function as key molecules in cancer progression. The lncRNA CYTOR plays oncogenic roles in multiple types of cancer, yet the detailed molecular mechanisms of those roles remain unknown. The aim of this study was to investigate the clinical significance, biological function and interacting partners of CYTOR in colorectal cancer (CRC). METHODS A systematic and comprehensive analysis of CYTOR expression was performed in 138 CRC samples and in the TCGA and GEO databases. Biological function was investigated through knockdown and overexpression of CYTOR in vitro and in vivo. In addition, its protein binding partner was identified and validated using ChIRP-MS and RNA immunoprecipitation assays. Their key interaction sites on CYTOR were verified by CRISPR/Cas9 and a series of mutant constructs. Furthermore, the downstream targets of CYTOR were confirmed via immunoblotting and luciferase reporter assays. RESULTS CYTOR was significantly up-regulated in CRC samples and associated with poor prognosis, promoting proliferation and metastasis in vitro and in vivo. NCL and Sam68 could recognize their specific motifs and directly bind to EXON1 of CYTOR. Moreover, EXON1 was the key functional site mediating the interaction of CYTOR with NCL and Sam68. NCL and Sam68 functioned as oncogenes to promote CRC progression. Furthermore, we confirmed that the heterotrimeric complex of CYTOR, NCL and Sam68 activated the NF-κB pathway and EMT to contribute to CRC progression. CONCLUSION CYTOR plays important roles in CRC progression by interacting with NCL and Sam68 and may serve as a prognostic biomarker and/or an effective target for CRC therapies.
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Affiliation(s)
- Xue Wang
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
- Department of Pharmacology, China Pharmaceutical University, Nanjing, 210009 China
| | - Hongfei Yu
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Wenjie Sun
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Jianlu Kong
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Lei Zhang
- Department of Pharmacology, China Pharmaceutical University, Nanjing, 210009 China
| | - Jinlong Tang
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Jingyu Wang
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Enping Xu
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Maode Lai
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
- Department of Pharmacology, China Pharmaceutical University, Nanjing, 210009 China
| | - Honghe Zhang
- Department of Pathology, Key Laboratory of Disease Proteomics of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058 China
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23
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Li N, Ngo CTA, Aleynikova O, Beauchemin N, Richard S. The p53 status can influence the role of Sam68 in tumorigenesis. Oncotarget 2018; 7:71651-71659. [PMID: 27690217 PMCID: PMC5342108 DOI: 10.18632/oncotarget.12305] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/20/2016] [Indexed: 02/02/2023] Open
Abstract
The expression and activities of RNA binding proteins are frequently dysregulated in human cancer. Their roles, however, appears to be complex, with reports indicating both pro-tumorigenic and tumor suppressive functions. Here we show, using two classical mouse cancer models, that the role of KH-type RNA binding protein, Sam68, in tumor development can be influenced by the status of the p53 tumor suppressor. We demonstrate that in mice expressing wild type p53, Sam68-deficiency resulted in a higher incidence and malignancy of carcinogen-induced tumors, suggesting a tumor suppressive role for Sam68. In marked contrast, Sam68-haploinsufficiency significantly delayed the onset of tumors in mice lacking p53 and prolonged their survival, indicating that Sam68 accelerates the development of p53-deficient tumors. These findings provide considerable insight into a previously unknown relationship between Sam68 and the p53 tumor suppressor in tumorigenesis.
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Affiliation(s)
- Naomi Li
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
| | - Chau Tuan-Anh Ngo
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
| | - Olga Aleynikova
- Department of Pathology, Jewish General Hospital, Montréal, Québec H3T 1E2, Canada
| | - Nicole Beauchemin
- Department of Medicine and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada.,Department of Biochemistry, McGill University, Montréal, Québec H3G 1Y6, Canada.,Rosalind and Morris Goodman Cancer Centre, Montréal, Québec H3A 1A3, Canada
| | - Stéphane Richard
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
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24
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Abstract
Src-associated in mitosis of 68 kDa (Sam68), also known as KHDRBS1 (KH domain-containing, RNA-binding, signal transduction-associated 1), is a member of the signal transduction and activation of RNA family. Previous studies have demonstrated that the aberrant expression of Sam68 is associated with the progression and prognosis of a variety of cancers, but little is known about its expression and role in chordomas, which are rare and aggressive bone neoplasms. In this study, we analyzed 40 tumor tissues and 20 distant normal tissues obtained from 40 patients with sacral chordoma using immunohistochemistry, and observed the expression of Sam68 was significantly upregulated in sacral chordomas compared with normal tissues (P=0.001). A positive correlation between the expression of Sam68 and the cell proliferation index Ki-67 was determined using Spearman’s rank correlation test (γ =0.599, P<0.001). In addition, high expression of Sam68 was significantly associated with surrounding muscle invasion (P<0.001). Moreover, Kaplan–Meier curves showed that patients with overexpressed Sam68 had shorter local recurrence-free survival time (P<0.001). Lastly, multivariate analysis indicated that Sam68 is an independent prognostic factor for the local recurrence-free survival of sacral chordomas (hazard ratio =5.929, 95% CI: 1.092–32.188, P=0.039). Our findings suggest the use of Sam68 as a predictor for the recurrence of sacral chordomas.
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Affiliation(s)
- Hai Wen
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Pengzhi Li
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Hong Ma
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jiaoyun Zheng
- Department of Pathology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yipin Yu
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Guohua Lv
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
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25
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Li X, Zhou X, Hua F, Fan Y, Zu L, Wang Y, Shen W, Pan H, Zhou Q. The RNA-binding protein Sam68 is critical for non-small cell lung cancer cell proliferation by regulating Wnt/β-catenin pathway. Int J Clin Exp Pathol 2017; 10:8281-8291. [PMID: 31966679 PMCID: PMC6965395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 06/20/2017] [Indexed: 06/10/2023]
Abstract
Src associated in mitosis, 68 kDa (Sam68) is a KH domain RNA-binding protein that regulates a broad scope of biological events, including RNA metabolism, transcription and signal transduction. Herein, we aimed to explore the expression, clinical significance and biological function of Sam68 in human non-small cell lung cancer (NSCLC). By applying quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry (IHC) methods, we found that nucleic localized Sam68 was markedly overexpressed in NSCLC tissues and cell lines. By X2 analysis and Kaplan-Meier survivial analysis between Sam68 expression and various clinicopathological features, Sam68 was found to be significantly associated with clinical T stage, advanced tumor grade, and short overall survival. Finally, in vitro loss-of-function studies showed that knockdown of Sam68 inhibited cell proliferation, colony formation and cell cycle progression in NSCLC cells. Moreover, our results clarified that knockdown of Sam68 could suppress NSCLC cell proliferation via the inhibition of Wnt/β-catenin pathway. To conclude, our results demonstrated that upregulation of Sam68 in NSCLC resulted in poor prognosis, and it promoted cell proliferation via activating Wnt/β-catenin signaling pathway, which could serve as a novel biomarker for the prognosis and therapy of NSCLC.
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Affiliation(s)
- Xuebing Li
- Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General HospitalTianjin, P. R. China
| | - Xuexia Zhou
- Department of Neuropathology, Tianjin Key Laboratory of Injuries, Variations and Regeneration of The Nervous System, Key Laboratory of Post-Trauma Neuro- Repair and Regeneration in Central Nervous System of Education Ministry, Tianjin Neurological Institute, Tianjin Medical University General HospitalTianjin, P. R. China
| | - Feng Hua
- Department of Thoracic Surgery, Shandong Cancer Hospital and InstituteJinan, P. R. China
| | - Yaguang Fan
- Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General HospitalTianjin, P. R. China
| | - Lingling Zu
- Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General HospitalTianjin, P. R. China
| | - Yuli Wang
- Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General HospitalTianjin, P. R. China
| | - Wang Shen
- Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General HospitalTianjin, P. R. China
| | - Hongli Pan
- Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General HospitalTianjin, P. R. China
| | - Qinghua Zhou
- Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Tianjin Lung Cancer Institute, Tianjin Medical University General HospitalTianjin, P. R. China
- Sichuan Lung Cancer Institute, Sichuan Lung Cancer Center, West China Hospital, Sichuan UniversityChengdu, P. R. China
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26
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Gaytan-Cervantes J, Gonzalez-Torres C, Maldonado V, Zampedri C, Ceballos-Cancino G, Melendez-Zajgla J. Protein Sam68 regulates the alternative splicing of survivin DEx3. J Biol Chem 2017; 292:13745-13757. [PMID: 28655776 DOI: 10.1074/jbc.m117.800318] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Indexed: 01/31/2023] Open
Abstract
Messenger RNA alternative splicing (AS) regulates the expression of a variety of genes involved in both physiological and pathological processes. AS of the anti-apoptotic and proliferation-associated survivin (BIRC5) gene generates six isoforms, which regulate key aspects of cancer initiation and progression. One of the isoforms is survivin DEx3, in which the exclusion of exon 3 generates a unique carboxyl terminus with specific anti-apoptotic functions. This isoform is highly expressed in advanced stages of breast and cervical tumors. Therefore, understanding the mechanisms that regulate survivin DEx3 mRNA AS is clearly important. To this end, we designed a minigene (M), and in combination with a series of deletions and site-directed mutations, we determined that the first 22 bp of exon 3 contain cis-acting elements that enhance the exclusion of exon 3 to generate the survivin DEx3 mRNA isoform. Furthermore, using pulldown assays, we discovered that Sam68 is a possible trans-acting factor that binds to this region and regulates exon 3 splicing. This result was corroborated using a cell line in which the Sam68 binding site in the survivin gene was mutated with the CRISPR/Cas system. This work provides the first clues regarding the regulation of survivin DEx3 mRNA splicing.
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Affiliation(s)
| | | | - Vilma Maldonado
- Epigenetics, National Institute of Genomic Medicine (INMEGEN), 14610 Mexico City, Mexico
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27
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Benoit YD, Mitchell RR, Risueño RM, Orlando L, Tanasijevic B, Boyd AL, Aslostovar L, Salci KR, Shapovalova Z, Russell J, Eguchi M, Golubeva D, Graham M, Xenocostas A, Trus MR, Foley R, Leber B, Collins TJ, Bhatia M. Sam68 Allows Selective Targeting of Human Cancer Stem Cells. Cell Chem Biol 2017. [PMID: 28648376 DOI: 10.1016/j.chembiol.2017.05.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Targeting of human cancer stem cells (CSCs) requires the identification of vulnerabilities unique to CSCs versus healthy resident stem cells (SCs). Unfortunately, dysregulated pathways that support transformed CSCs, such as Wnt/β-catenin signaling, are also critical regulators of healthy SCs. Using the ICG-001 and CWP family of small molecules, we reveal Sam68 as a previously unappreciated modulator of Wnt/β-catenin signaling within CSCs. Disruption of CBP-β-catenin interaction via ICG-001/CWP induces the formation of a Sam68-CBP complex in CSCs that alters Wnt signaling toward apoptosis and differentiation induction. Our study identifies Sam68 as a regulator of human CSC vulnerability.
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Affiliation(s)
- Yannick D Benoit
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Ryan R Mitchell
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Ruth M Risueño
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Luca Orlando
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Borko Tanasijevic
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Allison L Boyd
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Lili Aslostovar
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada; Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada
| | - Kyle R Salci
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada
| | - Zoya Shapovalova
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Jennifer Russell
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Masakatsu Eguchi
- Theriac Pharmaceutical Corporation Research Institute, 600 Broadway Suite 580 Fl 5, Seattle, WA 98122, USA
| | - Diana Golubeva
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada
| | - Monica Graham
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Anargyros Xenocostas
- Department of Medicine, Division of Hematology, Schulich School of Medicine, University of Western Ontario, London, ON N6A 3K7, Canada
| | - Michael R Trus
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Ronan Foley
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Brian Leber
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Tony J Collins
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada
| | - Mickie Bhatia
- McMaster Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, 1280 Main Street West, MDCL 5029, Hamilton, ON L8S 4L8, Canada; Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada.
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28
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Li N, Hébert S, Song J, Kleinman CL, Richard S. Transcriptome profiling in preadipocytes identifies long noncoding RNAs as Sam68 targets. Oncotarget 2017; 8:81994-82005. [PMID: 29137239 PMCID: PMC5669865 DOI: 10.18632/oncotarget.17813] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 04/17/2017] [Indexed: 11/25/2022] Open
Abstract
The KH-type RNA binding protein Sam68 is required for adipogenesis. We have previously shown that Sam68-deficient mice have a lean phenotype and are protected against dietary-induced obesity due to defects in mTOR and S6K1 alternative splicing. Herein we profiled the transcriptome of Sam68 wild type and deficient 3T3-L1 mouse preadipocytes. We identified 652 protein-coding genes and 9 ncRNAs that were significantly altered with the loss of Sam68. As expected, downregulated genes were significantly associated with GO terms linked to cell migration, motility, and fat cell differentiation, while upregulated genes were mostly associated with GO terms linked to neurogenesis. Of the lncRNAs, we identified Hotair, Mir155hg, as well as two new lncRNAs (SR-lncRNA-1 and SR-lncRNA-2) that were regulated by Sam68, and contained consensus Sam68 binding sites. RNA stability assays showed that Sam68-deficiency decreased the half-life of Hotair, and increased the half-lives of Mir155hg and SR-lncRNA-2, while the stability of SR-lncRNA-1 was unaffected. Depletion of Hotair and SR-lncRNA-1 in wild type 3T3-L1 cells led to defects in adipogenesis, whereas depletion of SR-lncRNA-2 in Sam68-deficient 3T3-L1 cells partially rescued the adipogenesis defect observed in these cells. Collectively, our findings define a new role for Sam68 as a regulator of lncRNAs during adipogenic differentiation.
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Affiliation(s)
- Naomi Li
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine, McGill University, Montréal, Québec H3A 1A1, Canada.,Department of Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
| | - Steven Hébert
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Human Genetics, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Jingwen Song
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine, McGill University, Montréal, Québec H3A 1A1, Canada.,Department of Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
| | - Claudia L Kleinman
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Human Genetics, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Stéphane Richard
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine, McGill University, Montréal, Québec H3A 1A1, Canada.,Department of Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
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Gutkoska J, LaRocco M, Ramirez-Medina E, de Los Santos T, Lawrence P. Host microRNA-203a Is antagonistic to the progression of foot-and-mouth disease virus infection. Virology 2017; 504:52-62. [PMID: 28152384 DOI: 10.1016/j.virol.2017.01.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 01/22/2017] [Accepted: 01/23/2017] [Indexed: 12/11/2022]
Abstract
Sam68 was previously shown to be a critical host factor for foot-and-mouth disease virus (FMDV) replication. MicroRNA (miR) miR-203a is reportedly a negative regulator of Sam68 expression both in vitro and in vivo. Here, transfection of miR-203a-3p and miR-203a-5p mimics separately and in combination in a porcine cell line followed by FMDV infection resulted in diminished viral protein synthesis and a 4 and 6log reduction in virus titers relative to negative controls, respectively. Unexpectedly, Sam68 expression was increased by miR-203a-5p transfection, but not miR-203a-3p. miR-203a-5p also down-regulated Survivin expression, which was predicted to play a role in FMDV infection. Moreover, miR-203a-5p but not miR-203a-3p affected a reduction in FMDV viral RNA. These effects were not replicated with a related Picornavirus, suggesting FMDV specificity. Importantly, miR-203a-3p and miR-203a-5p impaired FMDV infection across multiple FMDV serotypes. We concluded that miR-203a-3p and miR-203a-5p represent attractive potential naturally occurring bio-therapeutics against FMDV.
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Affiliation(s)
- Joseph Gutkoska
- Plum Island Animal Disease Center Foreign Animal Disease Research Unit (FADRU) Agricultural Research Service (ARS), United States Department of Agriculture (USDA), 40550 Route 25, Orient Point, NY 11957, United States
| | - Michael LaRocco
- Plum Island Animal Disease Center Foreign Animal Disease Research Unit (FADRU) Agricultural Research Service (ARS), United States Department of Agriculture (USDA), 40550 Route 25, Orient Point, NY 11957, United States
| | - Elizabeth Ramirez-Medina
- Plum Island Animal Disease Center Foreign Animal Disease Research Unit (FADRU) Agricultural Research Service (ARS), United States Department of Agriculture (USDA), 40550 Route 25, Orient Point, NY 11957, United States
| | - Teresa de Los Santos
- Plum Island Animal Disease Center Foreign Animal Disease Research Unit (FADRU) Agricultural Research Service (ARS), United States Department of Agriculture (USDA), 40550 Route 25, Orient Point, NY 11957, United States
| | - Paul Lawrence
- Plum Island Animal Disease Center Foreign Animal Disease Research Unit (FADRU) Agricultural Research Service (ARS), United States Department of Agriculture (USDA), 40550 Route 25, Orient Point, NY 11957, United States.
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Fu K, Sun X, Wier EM, Hodgson A, Hobbs RP, Wan F. Sam68/KHDRBS1-dependent NF-κB activation confers radioprotection to the colon epithelium in γ-irradiated mice. eLife 2016; 5. [PMID: 27996939 PMCID: PMC5214542 DOI: 10.7554/elife.21957] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 12/19/2016] [Indexed: 12/20/2022] Open
Abstract
Previously we reported that Src-associated-substrate-during-mitosis-of-68kDa (Sam68/KHDRBS1) is pivotal for DNA damage-stimulated NF-κB transactivation of anti-apoptotic genes (Fu et al., 2016). Here we show that Sam68 is critical for genotoxic stress-induced NF-κB activation in the γ-irradiated colon and animal and that Sam68-dependent NF-κB activation provides radioprotection to colon epithelium in vivo. Sam68 deletion diminishes γ-irradiation-triggered PAR synthesis and NF-κB activation in colon epithelial cells (CECs), thus hampering the expression of anti-apoptotic molecules in situ and facilitating CECs to undergo apoptosis in mice post whole-body γ-irradiation (WBIR). Sam68 knockout mice suffer more severe damage in the colon and succumb more rapidly from acute radiotoxicity than the control mice following WBIR. Our results underscore the critical role of Sam68 in orchestrating genotoxic stress-initiated NF-κB activation signaling in the colon tissue and whole animal and reveal the pathophysiological relevance of Sam68-dependent NF-κB activation in colonic cell survival and recovery from extrinsic DNA damage. DOI:http://dx.doi.org/10.7554/eLife.21957.001
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Affiliation(s)
- Kai Fu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Xin Sun
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Eric M Wier
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Andrea Hodgson
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Ryan P Hobbs
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Fengyi Wan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States.,Department of Oncology, School of Medicine, Johns Hopkins University, Baltimore, United States.,The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, United States
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La Rosa P, Bielli P, Compagnucci C, Cesari E, Volpe E, Farioli Vecchioli S, Sette C. Sam68 promotes self-renewal and glycolytic metabolism in mouse neural progenitor cells by modulating Aldh1a3 pre-mRNA 3'-end processing. eLife 2016; 5. [PMID: 27845622 PMCID: PMC5122457 DOI: 10.7554/elife.20750] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/14/2016] [Indexed: 12/20/2022] Open
Abstract
The balance between self-renewal and differentiation of neural progenitor cells (NPCs) dictates neurogenesis and proper brain development. We found that the RNA- binding protein Sam68 (Khdrbs1) is strongly expressed in neurogenic areas of the neocortex and supports the self-renewing potential of mouse NPCs. Knockout of Khdrbs1 constricted the pool of proliferating NPCs by accelerating their cell cycle exit and differentiation into post-mitotic neurons. Sam68 function was linked to regulation of Aldh1a3 pre-mRNA 3'-end processing. Binding of Sam68 to an intronic polyadenylation site prevents its recognition and premature transcript termination, favoring expression of a functional enzyme. The lower ALDH1A3 expression and activity in Khdrbs1-/- NPCs results in reduced glycolysis and clonogenicity, thus depleting the embryonic NPC pool and limiting cortical expansion. Our study identifies Sam68 as a key regulator of NPC self-renewal and establishes a novel link between modulation of ALDH1A3 expression and maintenance of high glycolytic metabolism in the developing cortex. DOI:http://dx.doi.org/10.7554/eLife.20750.001 Neurons develop from cells called neural progenitors. These cells can either divide to produce more progenitor cells or develop into specific types of neurons. These two activities – known as self-renewal and differentiation – must be balanced to produce the right number of specialized neurons, without depleting the pool of progenitor cells. The self-renewal and differentiation of progenitor cells is balanced by essentially regulating which genes are active, or expressed, within the cells. In the first step of gene expression, the genetic instructions are copied to form a molecule of pre-messenger RNA (or pre-mRNA for short). Each pre-mRNA molecule is then processed to produce a final product that can be translated into protein. Importantly, two copies of the same pre-mRNA may sometimes be processed in different ways, which allows multiple proteins to be produced from a single gene. RNA-binding proteins control pre-mRNA processing. The expression of one such protein, called Sam68, oscillates during the development of the nervous system, such that its expression peaks when there is intense production of new neurons and then declines. However, it was not known whether Sam68 actually helps neurons to develop. La Rosa et al. have now analysed the role of Sam68 in the developing brain of mice. The experiments confirmed that Sam68 is highly expressed in neural progenitor cells and showed that its levels dictate the cell’s fate: high expression encourages a cell to self-renew, while low expression triggers it to develop into a specialized neuron. Further investigation revealed that Sam68 works by promoting the expression of a metabolic enzyme called Aldehyde Dehydrogenase 1A3 or ALDH1A3. This enzyme promotes the release of energy from molecules of glucose via a process known as anaerobic glycolysis. La Rosa et al. found that cells that lack Sam68 make a truncated version of the pre-mRNA encoding ALDH1A3. This truncated pre-mRNA encodes a shortened version of the enzyme that is inactive. Further experiments confirmed that Sam68 normally prevents this from happening by binding to the pre-mRNA and processing it to produce the full-length, working version of the ALDH1A3 enzyme. Also, La Rosa et al. found that progenitor cells need working ALDH1A3 to keep them dividing, and to stop them from developing into specialized neurons too soon. Finally, because the processing of pre-RNA plays a major role in brain development, problems with this process often lead to intellectual disabilities and neurodegenerative diseases, such as autism spectrum disorder and amyotrophic lateral sclerosis. The next step following on from these new findings will be to investigate whether defects in Sam68 contribute to such conditions and, if so, to look for ways to counteract these defects. DOI:http://dx.doi.org/10.7554/eLife.20750.002
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Affiliation(s)
- Piergiorgio La Rosa
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - Pamela Bielli
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - Claudia Compagnucci
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - Eleonora Cesari
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - Elisabetta Volpe
- Laboratory of Neuroimmunology, Fondazione Santa Lucia, Rome, Italy
| | | | - Claudio Sette
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
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Wang Y, Zhang W, Wang X, Wang D, Xie J, Tang C, Xi Q, Zhong J, Deng Y. Expression of Sam68 Correlates With Cell Proliferation and Survival in Epithelial Ovarian Cancer. Reprod Sci 2016; 24:97-108. [PMID: 27222230 DOI: 10.1177/1933719116650757] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Src associated in mitosis, 68 kDa (Sam68) is a KH domain RNA-binding protein that belongs to the signal transduction and activation of RNA family. It is a multifunctional protein known to regulate cellular signal transduction, transcription, RNA metabolism, proliferation, and apoptosis, thus implicated in tumor growth. Herein, we investigated the clinical significance of Sam68 in human epithelial ovarian cancer (EOC). Western blot and immunohistochemical staining demonstrated that Sam68 expression was upregulated in EOC tissues and cell lines. Statistical analysis showed that high expression of Sam68 correlated with poor prognosis of patients with EOC. In vitro, serum starvation-refeeding experiment was primarily performed to confirm that Sam68 participated in the cell cycle progression of EOC cell lines. Then knocking down Sam68 level with small interfering RNA, cell cycle was arrested at G1 phase and cell proliferation impaired. Furthermore, we demonstrated that the antiproliferative effect of silencing Sam68 in EOC cells was associated with the upregulation of cyclin-dependent kinase inhibitors p21Cip1 and p27Kip1, along with the downregulation of p-FOXO3a, p-Akt, and p-GSK-3β. Taken together, our findings uncovered that Sam68 played an important role in promoting the proliferation of human ovarian cancer, thereby might be a novel therapeutic target for EOC.
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Affiliation(s)
- Yingying Wang
- 1 Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Department of Pathogen Biology, Medical College, Nantong University, Nantong, People's Republic of China
| | - Weiwei Zhang
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Xia Wang
- 3 Center for Reproductive Medicine, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Di Wang
- 3 Center for Reproductive Medicine, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Juan Xie
- 3 Center for Reproductive Medicine, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Chunhui Tang
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Qinghua Xi
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Jianxin Zhong
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Yan Deng
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
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Chen S, Li H, Zhuang S, Zhang J, Gao F, Wang X, Chen W, Song M. Sam68 reduces cisplatin-induced apoptosis in tongue carcinoma. J Exp Clin Cancer Res 2016; 35:123. [PMID: 27473117 PMCID: PMC4966777 DOI: 10.1186/s13046-016-0390-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 07/06/2016] [Indexed: 01/01/2023]
Abstract
Background Resistance to anticancer agents is a major obstacle for successful chemotherapy in tongue squamous cancer. Sam68 is an oncogenic-related protein in oral tongue squamous cell carcinoma functions as a signaling molecule mediating apoptosis, whose over-expression is associated with the clinicopathologic characteristics and prognosis of patients. The present study was to examine the effect of Sam68 on chemotherapeutics-induced apoptosis in oral tongue squamous cell carcinoma, and its clinical significance in oral tongue squamous cell carcinoma progression. Methods The effect of Sam68 on apoptosis induced by cisplatin was examined both in vitro and in vivo, using Annexin V staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays. Real-time PCR and Western blotting analysis were used to detect mRNA and protein expression levels. Results Upregulation of Sam68 significantly inhibited cisplatin-induced apoptosis in oral tongue squamous cell carcinoma cells, associated with induction of anti-apoptotic proteins caspase-9, caspase-3, and PARP. In contrast, Silencing Sam68 expression significantly enhanced the sensitivity of oral tongue squamous cell carcinoma cells to apoptosis induced by cisplatin both in vitro and in vivo. Conclusions The current study suggests that Sam68 could enhance the anti-apoptosis activity of oral tongue squamous cell carcinoma cells. Sam68 is a potential pharmacologic target for the treatment of oral tongue squamous cell carcinoma and inhibition of Sam68 expression might represent a novel strategy to sensitize oral tongue squamous cell carcinoma to chemotherapy.
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Affiliation(s)
- Shuwei Chen
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.,Department of Head and Neck Surgery, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Huan Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.,Department of Intensive Care Unit, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Shimin Zhuang
- Department of Otolaryngology-Head and Neck Surgery, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Ji Zhang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.,Department of Head and Neck Surgery, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Fan Gao
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.,Department of Head and Neck Surgery, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Xidi Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.,Department of Head and Neck Surgery, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - WenKuan Chen
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China. .,Department of Head and Neck Surgery, Sun Yat-Sen University Cancer Center, Guangzhou, China.
| | - Ming Song
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China. .,Department of Head and Neck Surgery, Sun Yat-Sen University Cancer Center, Guangzhou, China.
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Fu K, Sun X, Wier EM, Hodgson A, Liu Y, Sears CL, Wan F. Sam68/KHDRBS1 is critical for colon tumorigenesis by regulating genotoxic stress-induced NF-κB activation. eLife 2016; 5. [PMID: 27458801 PMCID: PMC4959885 DOI: 10.7554/elife.15018] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/29/2016] [Indexed: 12/19/2022] Open
Abstract
Nuclear factor kappa B (NF-κB)-mediated transcription is an important mediator for cellular responses to DNA damage. Genotoxic agents trigger a 'nuclear-to-cytoplasmic' NF-κB activation signaling pathway; however, the early nuclear signaling cascade linking DNA damage and NF-κB activation is poorly understood. Here we report that Src-associated-substrate-during-mitosis-of-68kDa/KH domain containing, RNA binding, signal transduction associated 1 (Sam68/KHDRBS1) is a key NF-κB regulator in genotoxic stress-initiated signaling pathway. Sam68 deficiency abolishes DNA damage-stimulated polymers of ADP-ribose (PAR) production and the PAR-dependent NF-κB transactivation of anti-apoptotic genes. Sam68 deleted cells are hypersensitive to genotoxicity caused by DNA damaging agents. Upregulated Sam68 coincides with elevated PAR production and NF-κB-mediated anti-apoptotic transcription in human and mouse colon cancer. Knockdown of Sam68 sensitizes human colon cancer cells to genotoxic stress-induced apoptosis and genetic deletion of Sam68 dampens colon tumor burden in mice. Together our data reveal a novel function of Sam68 in the genotoxic stress-initiated nuclear signaling, which is crucial for colon tumorigenesis. DOI:http://dx.doi.org/10.7554/eLife.15018.001 Cells use signaling pathways to detect and respond to harmful conditions by switching on genes that keep the cell healthy. One important pathway is the nuclear factor kappa B (NF-κB) signaling pathway, which is activated by many stimuli. These stimuli may come from infections from outside the cell or may originate inside the cell, as seen for DNA damage caused by irradiation, chemicals or rapid DNA replication in cancer cells. Most of a cell’s DNA is located in the cell nucleus. However, NF-κB proteins are normally located outside the nucleus, in the cell’s cytoplasm. Damage to DNA triggers a signal from the nucleus to the cytoplasm. This signal activates the NF-κB proteins, which move into the nucleus and turn on genes that help the cell to recover from the damage. These genes include those that prevent the cell from self-destructing. In one step of the NF-κB activation process, chain-like molecules called polymers are made from a compound called poly(ADP-ribose), or PAR for short. However, few other details are known about how the damaged DNA in the nucleus signals to the cytoplasm. A protein called Sam68, which is found in the cell nucleus, has been linked to DNA damage signaling. Fu, Sun et al. now present evidence that suggests that if mouse cells lack Sam68, they do not produce PAR polymers in response to DNA damage. In addition, these cells could not trigger the PAR-dependent signaling cascade that is essential for activating NF-κB and for turning on the protective genes. Consequently, cells that lacked Sam68 were extremely sensitive to agents that cause DNA damage, such as chemicals and irradiation. The NF-κB pathway is regulated incorrectly in some cancers, but is also activated by DNA damage caused by cancer treatments. Therefore, Fu, Sun et al. also explored the role of Sam68 in cancer. Reducing the levels of Sam68 made human colon cancer cells more likely to self-destruct when they were exposed to DNA-damaging agents. Furthermore, removing Sam68 from mice that spontaneously grow colon cancer caused their tumors to develop more slowly than mice that retained Sam68 in their cells. Overall, the findings presented by Fu, Sun et al. suggest that Sam68 regulates the signal from the nucleus to the cytoplasm that activates NF-κB proteins in response to DNA damage. Sam68 also appears to be important for helping colon cancer cells grow and survive. Future challenges will be to understand how Sam68 regulates the production of the PAR polymer in this response and to explore whether Sam68 can be targeted for treating cancer. DOI:http://dx.doi.org/10.7554/eLife.15018.002
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Affiliation(s)
- Kai Fu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Xin Sun
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Eric M Wier
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Andrea Hodgson
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States.,W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, John Hopkins University, Baltimore, United States
| | - Yue Liu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Cynthia L Sears
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, John Hopkins University, Baltimore, United States.,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, United States.,Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Medical Institutions, Baltimore, United States
| | - Fengyi Wan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States.,Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Medical Institutions, Baltimore, United States
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Chen X, Liu L, Qian R, Liu J, Yao Y, Jiang Z, Song X, Ren J, Zhang F. Expression of Sam68 Associates with Neuronal Apoptosis and Reactive Astrocytes After Spinal Cord Injury. Cell Mol Neurobiol 2017; 37:487-98. [PMID: 27236696 DOI: 10.1007/s10571-016-0384-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 05/18/2016] [Indexed: 01/15/2023]
Abstract
Src-associated in mitosis (Sam68; 68 kDa) is a novel RNA-binding protein that belongs to the signal transduction and activation of RNA family involved in various biological processes. However, the expression and roles of Sam68 in the central nervous system remain unknown. In the present study, we performed a spinal cord injury (SCI) model in adult rats and found a significant increase of Sam68 protein levels in this model, which reached a peak at day 3 and then gradually returned to normal levels at day 14 after SCI. We use immunohistochemistry analysis revealing a widespread distribution of Sam68 in the spinal cord. In addition, double-immunofluorescence staining showed that Sam68 immunoreactivity was found predominantly in neurons and astrocytes. Moreover, colocalization of Sam68/active caspase-3 has been respectively detected in neuronal nuclei, and colocalization of Sam68/PCNA has been detected in glial fibrillary acidic protein. In vitro, we found that depletion of Sam68 by short interfering RNA inhibits neuronal apoptosis and astrocyte proliferation and decreases cyclin D1 protein levels. In conclusion, this is the first study to find the Sam68 expression in SCI. Our results suggest that Sam68 might be illustrated in the apoptosis of neurons and proliferation of astrocytes after SCI. This research will provide new drug targets for clinical treatment of SCI.
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Qian J, Zhao W, Miao X, Li L, Zhang D. Sam68 modulates apoptosis of intestinal epithelial cells via mediating NF-κB activation in ulcerative colitis. Mol Immunol 2016; 75:48-59. [PMID: 27235792 DOI: 10.1016/j.molimm.2016.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 05/11/2016] [Accepted: 05/13/2016] [Indexed: 12/19/2022]
Abstract
Sam68 (Src-associated substrate during mitosis of 68 KDa), also known as KHDRBS1 (KH domain containing, RNA binding, signal transduction associated 1), belongs to the prototypic member of the signal transduction activator of RNA (STAR) family of RNA-binding proteins. Sam68 is implicated in various cellular processes including RNA metabolism, apoptosis, signal transduction. Previous researches demonstrated that Sam68 regulated nuclear transcription factor kappa B (NF-κB) to induce inflammation. However, the expression and biological functions of Sam68 in ulcerative colitis (UC) are not clear. In this study, we reported for the first time that Sam68 was up-regulated in intestinal epithelial cells (IECs) of patients with UC. In DSS-induced mouse colitis model, we observed the overexpression of Sam68 accompanied with increased levels of IEC apoptotic markers (active caspase-3 and cleaved PARP) and NF-κB activation indicators (p-p65 and p-IκB) in colitis IECs. Co-localization of Sam68 with active caspase-3 (and p-p65) in IECs of the DSS-induced colitis group further indicated the possible involvement of NF-κB-mediated IEC apoptosis. Applying TNF-α-treated HT-29 cells as an in vitro IEC inflammation model, we confirmed the positive correlation amomg Sam68, NF-κB activation and caspase-dependent apoptosis. Immunofluorescence and immunoprecipitation assay identified nuclear translocation and physical interaction of Sam68 and NF-κB subunits in TNF-α-treated HT-29 cells. Besides, depletion of Sam68 by RNA interference greatly alleviated NF-κB activation and apoptosis in TNF-α-treated HT-29 cells. Taken together, our results indicated that Sam68 modulates apoptosis of intestinal epithelial cells via mediating NF-κB activation in UC.
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Affiliation(s)
- Ji Qian
- Department of Digestion Medicine, Affiliated Yixing Hospital of Jiangsu University, 75 Tongzhenguan Road, Yixing 214200, Jiangsu, People's Republic of China
| | - Weijuan Zhao
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong 226001, Jiangsu, People's Republic of China
| | - Xianjing Miao
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong 226001, Jiangsu, People's Republic of China
| | - Liren Li
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong 226001, Jiangsu, People's Republic of China.
| | - Dongmei Zhang
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, 19 Qixiu Road, Nantong 226001, Jiangsu, People's Republic of China
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Zhang H, Chen N, Li P, Pan Z, Ding Y, Zou D, Li L, Xiao L, Shen B, Liu S, Cao H, Cui Y. The nuclear protein Sam68 is recruited to the cytoplasmic stress granules during enterovirus 71 infection. Microb Pathog 2016; 96:58-66. [PMID: 27057671 DOI: 10.1016/j.micpath.2016.04.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 04/01/2016] [Indexed: 10/22/2022]
Abstract
Our previous study found that the nuclear protein, 68-kDa Src-associated in mitosis protein (Sam68), is translocated to the cytoplasm and forms punctate pattern during enterovirus 71 (EV71) infection [Virus Research, 180 (2014), 1-11]. However, the exact function of this punctate pattern in cytoplasm during EV71 infection remains unknown. In this study, we firstly have examined this punctate pattern of Sam68 re-localization in the cytoplasm, and observed the obvious recruitments of Sam68 to the EV71-induced stress granules (SGs). Sam68, belongs to the KH domain family of RNA binding proteins (RBPs), was then confirmed that its KH domain was essential for this recruitment. Nevertheless, Knockdown of Sam68 expression using ShRNA had no effects on SGs assembly, indicating that Sam68 is not a constitutive component of the SGs during EV71 infection. Lastly, we investigated the importance of microtubulin transport to SGs aggregation, and revealed that microtubule depolymerization inhibited SGs formation, suggesting that EV71-induced SGs move throughout the cytoplasm in a microtubule-dependent manner. Taken together, these results illuminated that EV71 infections can induce SGs formation, and Sam68, as a SGs component, migrates alone with SGs dependent on intact microtubule upon the viral infections. These findings may provide novel underlying mechanism for delineating the role of SGs during EV71 infection.
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Affiliation(s)
- Hua Zhang
- College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China; College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Ning Chen
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Pengfei Li
- Department of Nephrology, The Fifth Affiliated Hospital of Harbin Medical University, Daqing 163319, China
| | - Ziye Pan
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Yun Ding
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Dehua Zou
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Liyang Li
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Lijie Xiao
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Binglei Shen
- College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Shuxia Liu
- Daqing Branch of HeiLongJiang Academy of Sciences, Daqing 163319, China
| | - Hongwei Cao
- College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China; College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China.
| | - Yudong Cui
- College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China; College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China.
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Zhang T, Wan C, Shi W, Xu J, Fan H, Zhang S, Lin Z, Ni R, Zhang X. The RNA-binding protein Sam68 regulates tumor cell viability and hepatic carcinogenesis by inhibiting the transcriptional activity of FOXOs. J Mol Histol 2015; 46:485-97. [PMID: 26438629 DOI: 10.1007/s10735-015-9639-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 09/30/2015] [Indexed: 12/31/2022]
Abstract
Src associated in mitosis (Sam68; 68 kDa) is a KH domain RNA-binding protein that belongs to the signal transduction and activation of RNA family, and has been implicated in the oncogenesis and progression of several human cancers. Our study aimed to investigated the clinicopathologic significance of Sam68 expression and its role in cell proliferation and the underlying molecular mechanism in hepatocellular carcinoma (HCC). We demonstrated that Sam68 expression was significantly increased in HCC and high expression of Sam68 was significantly associated with Edmondson grade, tumor size, tumor nodule number, HBsAg status and Ki-67 expression. The Kaplan-Meier survival curves showed that increased expression of Sam68 was correlated with poor prognosis in HCC patients and served as an independent prognostic marker of overall survival in a multivariable analysis. In addition, through serum starvation and refeeding assay, we demonstrated that Sam68 was lowly expressed in serum-starved HCC cells, and was progressively increased after serum-additioning. Furthermore, siRNA knockdown of endogenous Sam68 inhibited cell proliferation and tumourigenicity of HCC cells in vitro, through blocking the G1 to S phase transition. Moreover, we reported that the anti-proliferative effect of silencing Sam68 was accompanied with up-regulated expression of cyclin-dependent kinase inhibitors, p21(Cip1) and p27(Kip1), enhanced transactivation of FOXO factors (FOXO4), and dysreuglation of Akt/GSK-3β signaling. Taken together, these findings provide a rational framework for the progression of HCC and thereby indicated that Sam68 might be a novel and useful prognostic marker and a potential target for human HCC treatment.
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Xu L, Sun C, Zhang S, Xu X, Zhai L, Wang Y, Wang S, Liu Z, Cheng H, Xiao M, Tao R, Zhang D. Sam68 Promotes NF-κB Activation and Apoptosis Signaling in Articular Chondrocytes during Osteoarthritis. Inflamm Res 2015; 64:895-902. [PMID: 26350037 DOI: 10.1007/s00011-015-0872-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 08/18/2015] [Accepted: 08/19/2015] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVES To investigate the expression of Sam68 in articular cartilage of knee osteoarthritis (OA) and the relationship between Sam68 and NF-κB activation and apoptosis signaling in OA articular chondrocytes. METHODS Sam68 expression in normal and osteoarthritic cartilage was assessed by immunohistochemistry and RT-PCR on both meniscal/ligamentous injury (MLI)-induced OA rat model and the clinical human OA cartilage tissues. Sam68 expression in chondrocytes under tumor necrosis factor-alpha (TNF-α) stimuli was also assessed by immunoblot. Inhibiting Sam68 in chondrocytes under TNF-α stimuli was conducted using small interfering RNA (siRNA) and its influence on the expression of apoptotic marker and catabolic genes was examined by immunoblot. The mechanism of how Sam68 stimulates NF-κB activity was determined by co-immunoprecipitation and immunoblot analysis of nuclear and cytoplasmic fractions of TNF-α-treated chondrocytes for p65 and Sam68. RESULTS Sam68 expression was increased in OA cartilage tissues and chondrocytes under TNF-α stimuli. Inhibition of Sam68 by siRNA significantly decreased the expression of apoptotic markers (cleaved caspase-3 and cleaved PARP) in chondrocytes following TNF-α-stimulation. Sam68 knockdown suppressed Iκ-B degradation and p65 nuclear transportation in TNF-α-treated chondrocytes, indicating a suppressed NF-κB activation. Upon TNF-α exposure, the nuclear transportation of Sam68 and its interaction with p65 was detected in chondrocytes. Furthermore, Sam68 knockdown also alleviated the TNF-α-induced catabolic marker (MMP13, ADAMTS5, iNOS and IL-6) expression. CONCLUSIONS The highly expressed Sam68 promotes NF-κB signaling activation, catabolic gene expression and cellular apoptosis in TNF-α-treated chondrocytes, which may provide better insights into the pathophysiology of OA and a potential target for its treatment.
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Nakka KK, Chaudhary N, Joshi S, Bhat J, Singh K, Chatterjee S, Malhotra R, De A, Santra MK, Dilworth FJ, Chattopadhyay S. Nuclear matrix-associated protein SMAR1 regulates alternative splicing via HDAC6-mediated deacetylation of Sam68. Proc Natl Acad Sci U S A 2015; 112:E3374-83. [PMID: 26080397 DOI: 10.1073/pnas.1418603112] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Pre-mRNA splicing is a complex regulatory nexus modulated by various trans-factors and their posttranslational modifications to create a dynamic transcriptome through alternative splicing. Signal-induced phosphorylation and dephosphorylation of trans-factors are known to regulate alternative splicing. However, the role of other posttranslational modifications, such as deacetylation/acetylation, methylation, and ubiquitination, that could modulate alternative splicing in either a signal-dependent or -independent manner remain enigmatic. Here, we demonstrate that Scaffold/matrix-associated region-binding protein 1 (SMAR1) negatively regulates alternative splicing through histone deacetylase 6 (HDAC6)-mediated deacetylation of RNA-binding protein Sam68 (Src-associated substrate during mitosis of 68 kDa). SMAR1 is enriched in nuclear splicing speckles and associates with the snRNAs that are involved in splice site recognition. ERK-MAPK pathway that regulates alternative splicing facilitates ERK-1/2-mediated phosphorylation of SMAR1 at threonines 345 and 360 and localizes SMAR1 to the cytoplasm, preventing its interaction with Sam68. We showed that endogenously, SMAR1 through HDAC6 maintains Sam68 in a deacetylated state. However, knockdown or ERK-mediated phosphorylation of SMAR1 releases the inhibitory SMAR1-HDAC6-Sam68 complex, facilitating Sam68 acetylation and alternative splicing. Furthermore, loss of heterozygosity at the Chr.16q24.3 locus in breast cancer cells, wherein the human homolog of SMAR1 (BANP) has been mapped, enhances Sam68 acetylation and CD44 variant exon inclusion. In addition, tail-vein injections in mice with human breast cancer MCF-7 cells depleted for SMAR1 showed increased CD44 variant exon inclusion and concomitant metastatic propensity, confirming the functional role of SMAR1 in regulation of alternative splicing. Thus, our results reveal the complex molecular mechanism underlying SMAR1-mediated signal-dependent and -independent regulation of alternative splicing via Sam68 deacetylation.
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Wang Y, Liang L, Zhang J, Li M, Zhu J, Gong C, Yang L, Zhu J, Chen L, Ni R. Sam68 promotes cellular proliferation and predicts poor prognosis in esophageal squamous cell carcinoma. Tumour Biol 2015; 36:8735-45. [PMID: 26050229 DOI: 10.1007/s13277-015-3631-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 05/31/2015] [Indexed: 12/14/2022] Open
Abstract
Sam68 (Src-associated in mitosis of 68 kD) is a KH domain RNA-binding protein. The expression of Sam68 was correlated with kinds of tumors. Yet, the expression mechanisms and physiological significance of Sam68 in ESCC remains unclear. In this study, we clarified a potential role of Sam68 in the treatment of ESCC. Western blot and immunohistochemistry (IHC) analysis revealed that the protein level of Sam68 was higher in ESCC tumor tissues and cell lines. In addition, IHC stain revealed that Sam68 was positively correlated with clinical pathologic variables such as tumor grade and tumor invasion. In addition, Sam68 could be an independent prognostic indicator for patients' overall survival. In vitro studies such as starvation and refeeding assay along with Sam68-shRNA transfection assay demonstrated that Sam68 expression promoted proliferation of ESCC cells. And Sam68 downregulation caused decreased rate of cell growth and colony formation. Reasons are associated with growth arrest of cell cycle at G1/S phase. Moreover, our results clarified that Sam68 could promote ESCC cell proliferation via the activation of Akt/GSK-3β pathway. This research indicated that Sam68 might accelerate the cell cycle progression and be considered as a new therapy target in ESCC.
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Affiliation(s)
- Yayun Wang
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Li Liang
- Department of Medical Oncology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Jianguo Zhang
- Department of Pathology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Mei Li
- Department of Medical Oncology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Junya Zhu
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Chen Gong
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Linlin Yang
- Department of Oncology, Affiliated Cancer Hospital of Nantong University, Nantong, 226361, Jiangsu, China
| | - Jia Zhu
- Department of Oncology, Affiliated Cancer Hospital of Nantong University, Nantong, 226361, Jiangsu, China
| | - Lingling Chen
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Runzhou Ni
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China.
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Cho SJ, Choi MH, Nam SY, Kim JY, Kim CS, Pyo S, Yang KH. Sam68 is cleaved by caspases under apoptotic cell death induced by ionizing radiation. J Radiat Res 2015; 56:287-293. [PMID: 25666188 PMCID: PMC4380058 DOI: 10.1093/jrr/rru113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 11/02/2014] [Accepted: 11/05/2014] [Indexed: 06/04/2023]
Abstract
The RNA-binding protein Sam68, a mitotic substrate of tyrosine kinases, has been reported to participate in the cell cycle, apoptosis, and signaling. In particular, overexpression of Sam68 protein is known to suppress cell growth and cell cycle progression in NIH3T3 cells. Although Sam68 is involved in many cellular activities, the function of Sam68, especially in response to apoptotic stimulation, is not well understood. In this study, we found that Sam68 protein is cleaved in immune cells undergoing apoptosis induced by γ-radiation. Moreover, we found that Sam68 cleavage was induced by apoptotic stimuli containing γ-radiation in a caspase-dependent manner. In particular, we showed that activated casepase-3, 7, 8 and 9 can directly cleave Sam68 protein through in vitro protease cleavage assay. Finally, we found that the knockdown of Sam68 attenuated γ-radiation-induced cell death and growth suppression. Conclusively, the cleavage of Sam68 is a new indicator for the cell damaging effects of ionizing radiation.
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Affiliation(s)
- Seong-Jun Cho
- KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea
| | - Moo Hyun Choi
- KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea
| | - Seon Young Nam
- KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea
| | - Ji Young Kim
- KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea
| | - Cha Soon Kim
- KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea
| | - Suhkneung Pyo
- College of Pharmacy, Sungkyunkwan University, Suwon City, Kyunggi-do, Korea
| | - Kwang Hee Yang
- KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea
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Rivers ER, Horton AJ, Hawk AF, Favre EG, Senf KM, Nietert PJ, Chang EY, Foley AC, Robinson CJ, Lee KH. Placental Nkx2-5 and target gene expression in early-onset and severe preeclampsia. Hypertens Pregnancy 2014; 33:412-26. [PMID: 24987805 PMCID: PMC4192008 DOI: 10.3109/10641955.2014.925564] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Preeclampsia (PE) affects 2-8% of pregnancies worldwide and is a significant source of maternal and neonatal morbidity and mortality. However, the mechanisms underlying PE are poorly understood and major questions regarding etiology and risk factors remain to be addressed. Our objective was to examine whether abnormal expression of the cardiovascular developmental transcription factor, Nkx2-5, was associated with early onset and severe preeclampsia (EOSPE). METHODS Using qPCR and immunohistochemical assay, we examined expression of Nkx2-5 and target gene expression in EOSPE and control placental tissue. We tested resulting mechanistic hypotheses in cultured cells using shRNA knockdown, qPCR, and western blot. RESULTS Nkx2-5 is highly expressed in racially disparate fashion (Caucasians > African Americans) in a subset of early EOSPE placentae. Nkx2-5 mRNA expression is highly correlated (Caucasians > African Americans) to mRNA expression of the preeclampsia marker sFlt-1, and of the Nkx2-5 target and RNA splicing factor, Sam68. Knockdown of Sam68 expression in cultured cells significantly impacts sFlt-1 mRNA isoform generation in vitro, supporting a mechanistic hypothesis that Nkx2-5 impacts EOSPE severity in a subset of patients via upregulation of Sam68 to increase sFlt-1 expression. Expression of additional Nkx2-5 targets potentially regulating metabolic stress response is also elevated in a racially disparate fashion in EOSPE. CONCLUSIONS Expression of Nkx2-5 and its target genes may directly influence the genesis and racially disparate severity, and define a mechanistically distinct subclass of EOSPE.
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Affiliation(s)
- Elena R. Rivers
- Department of Pediatrics, Children’s Hospital, Medical University of South Carolina, Charleston, SC
| | - Anthony J. Horton
- Department of Pediatrics, Children’s Hospital, Medical University of South Carolina, Charleston, SC
| | - Angela F. Hawk
- Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC
| | - Elizabeth G. Favre
- Department of Pediatrics, Children’s Hospital, Medical University of South Carolina, Charleston, SC
| | - Katherine M. Senf
- Department of Pediatrics, Children’s Hospital, Medical University of South Carolina, Charleston, SC
| | - Paul J. Nietert
- Department of Public Health Sciences, Medical University of South Carolina, Charleston, SC
| | - Eugene Y. Chang
- Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC
| | - Ann C. Foley
- Department of Pediatrics, Children’s Hospital, Medical University of South Carolina, Charleston, SC
- Regenerative Medicine, Cell Biology and Anatomy Department, Medical University of South Carolina, Charleston, SC
- Bioengineering Department, Clemson University, Charleston, SC
| | | | - Kyu-Ho Lee
- Department of Pediatrics, Children’s Hospital, Medical University of South Carolina, Charleston, SC
- Regenerative Medicine, Cell Biology and Anatomy Department, Medical University of South Carolina, Charleston, SC
- Bioengineering Department, Clemson University, Charleston, SC
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Foot JN, Feracci M, Dominguez C. Screening protein--single stranded RNA complexes by NMR spectroscopy for structure determination. Methods 2014; 65:288-301. [PMID: 24096002 PMCID: PMC3959648 DOI: 10.1016/j.ymeth.2013.09.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/16/2013] [Accepted: 09/24/2013] [Indexed: 12/23/2022] Open
Abstract
In the past few years, RNA molecules have been revealed to be at the center of numerous biological processes. Long considered as passive molecules transferring genetic information from DNA to proteins, it is now well established that RNA molecules play important regulatory roles. Associated with that, the number of identified RNA binding proteins (RBPs) has increased considerably and mutations in RNA molecules or RBP have been shown to cause various diseases, such as cancers. It is therefore crucial to understand at the molecular level how these proteins specifically recognise their RNA targets in order to design new generation drug therapies targeting protein-RNA complexes. Nuclear magnetic resonance (NMR) is a particularly well-suited technique to study such protein-RNA complexes at the atomic level and can provide valuable information for new drug discovery programs. In this article, we describe the NMR strategy that we and other laboratories use for screening optimal conditions necessary for structural studies of protein-single stranded RNA complexes, using two proteins, Sam68 and T-STAR, as examples.
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Affiliation(s)
- Jaelle N Foot
- Department of Biochemistry, Henry Wellcome Laboratories of Structural Biology, University of Leicester, UK
| | - Mikael Feracci
- Department of Biochemistry, Henry Wellcome Laboratories of Structural Biology, University of Leicester, UK
| | - Cyril Dominguez
- Department of Biochemistry, Henry Wellcome Laboratories of Structural Biology, University of Leicester, UK.
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Abstract
Background Neuroblastoma (NB) is the most common solid extracranial tumor in children. However, the molecular mechanism and progression of NB is largely unknown, and unfortunately, the prognosis is poor. Src-associated in mitosis with a molecular weight of 68 kDa (Sam68) is associated with carcinogenesis and neurogenesis. The present study aimed to investigate the clinical and prognostic significance of Sam68 in NB. Methods The expression of Sam68 in immortalized normal epithelial cells, NB cell lines, and in four cases of paired NB tissue and adjacent normal tissue from the same patient was examined using Western blotting, reverse transcription-polymerase chain reaction (PCR) and real-time reverse transcription-PCR. The proliferation of NB cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, Sam68 protein expression was analyzed in 90 NB cases characterized as clinicopathological using immunohistochemistry. Statistical analyses were applied to evaluate the diagnostic value and associations of Sam68 with clinical parameters. Results Western blotting and reverse transcription-PCR showed that the expression level of Sam68 was markedly higher in NB cell lines than in the immortalized normal epithelial cells at both messenger RNA and protein levels. The MTT assay revealed that Sam68 expression supported proliferation of NB cells. Sam68 expression levels were significantly up-regulated in tumor tissues in comparison to the matched adjacent normal tissues from the same patient. Sam68 protein level was positively correlated with clinical stage (P<0.001), tumor histology (P<0.001), and distant metastasis (P=0.029). Patients with higher Sam68 expression had shorter overall survival time, whereas those with lower tumor Sam68 expression had longer survival time. Conclusion Our results suggest that Sam68 expression is associated with neuroblastoma progression and may represent a novel and valuable predictor for prognostic evaluation of neuroblastoma patients.
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Affiliation(s)
- Xiaohong Zhao
- Department of Pediatric Surgery, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
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Abstract
Alternative splicing is well known to be tissue-specific. Although several genes have been shown to undergo alternative splicing in adipocytes, little is known about the mechanism that regulates alternative splicing during adipogenesis. We recently reported that Sam68−/− mice exhibit a lean phenotype and are protected against diet-induced obesity. Our genome-wide exon array analysis in white adipose tissue (WAT) from wild-type and Sam68−/− mice revealed that Sam68 deficiency leads to an abnormal splicing of the mTOR gene. This has been shown to reduce the overall mTOR protein content and activity during in vitro adipose differentiation. In Sam68−/− mice, this situation leads to an increased energy expenditure, decreased adipogenesis and WAT formation.
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