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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] [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] [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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Glotzbach K, Faissner A. Substrate-bound and soluble domains of tenascin-C regulate differentiation, proliferation and migration of neural stem and progenitor cells. Front Cell Neurosci 2024; 18:1357499. [PMID: 38425428 PMCID: PMC10902920 DOI: 10.3389/fncel.2024.1357499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 01/23/2024] [Indexed: 03/02/2024] Open
Abstract
Introduction The lack of regenerative capacity of the central nervous system is one of the major challenges nowadays. The knowledge of guidance cues that trigger differentiation, proliferation, and migration of neural stem and progenitor cells is one key element in regenerative medicine. The extracellular matrix protein tenascin-C (Tnc) is a promising candidate to regulate cell fate due to its expression in the developing central nervous system and in the adult neural stem cell niches. Of special interest are the alternatively spliced fibronectin type III (FnIII) domains of Tnc whose combinatorial diversity could theoretically generate up to 64 isoforms in the mouse. A total of 27 isoforms have already been discovered in the developing brain, among others the domain combinations A1D, CD, and A124BCD. Methods In the present study, these domains as well as the combination of the constitutively expressed FnIII domains 7 and 8 (78) were expressed in Chinese hamster ovary cells as pseudo-antibodies fused to the Fc-fragment of a human immunoglobulin G antibody. The fusion proteins were presented to primary mouse neural stem/progenitor cells (NSPCs) grown as neurospheres, either as coated culture substrates or as soluble additives in vitro. The influence of the domains on the differentiation, proliferation and migration of NSPCs was analyzed. Results We observed that the domain combination A124BCD promoted the differentiation of neurons and oligodendrocytes, whereas the domain A1D supported astrocyte differentiation. The constitutively expressed domain 78 had a proliferation and migration stimulating impact. Moreover, most effects were seen only in one of the presentation modes but not in both, suggesting different effects of the Tnc domains in two- and three-dimensional cultures. Discussion This knowledge about the different effect of the Tnc domains might be used to create artificial three-dimensional environments for cell transplantation. Hydrogels spiked with Tnc-domains might represent a promising tool in regenerative medicine.
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Affiliation(s)
| | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
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Dabrowski KR, Floris G, Gillespie A, Daws SE. Orbitofrontal intronic circular RNA from Nrxn3 mediates reward learning and motivation for reward. Prog Neurobiol 2024; 232:102546. [PMID: 38036039 PMCID: PMC10843848 DOI: 10.1016/j.pneurobio.2023.102546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/27/2023] [Accepted: 11/20/2023] [Indexed: 12/02/2023]
Abstract
The orbitofrontal cortex (OFC) is a vital component of brain reward circuitry that is important for reward seeking behavior. However, OFC-mediated molecular mechanisms underlying rewarding behavior are understudied. Here, we report the first circular RNA (circRNA) profile associated with appetitive reward and identify regulation of 92 OFC circRNAs by sucrose self-administration. Among these changes, we observed downregulation of circNrxn3, a circRNA originating from neurexin 3 (Nrxn3), a gene involved in synaptogenesis, learning, and memory. Transcriptomic profiling via RNA sequencing and qPCR of the OFC following in vivo knock-down of circNrxn3 revealed differential regulation of genes associated with pathways important for learning and memory and altered splicing of Nrxn3. Furthermore, circNrxn3 knock-down enhanced sucrose self-administration and motivation for sucrose. Using RNA-immunoprecipitation, we report binding of circNrxn3 to the known Nrxn3 splicing factor SAM68. circNrxn3 is the first reported circRNA capable of regulating reward behavior and circNrxn3-mediated interactions with SAM68 may impact subsequent downstream processing of RNAs such as the regulation of gene expression and splicing.
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Affiliation(s)
- Konrad R Dabrowski
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA; Department of Biology, Temple University, Philadelphia, PA, USA
| | - Gabriele Floris
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA; Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Aria Gillespie
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA; Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Stephanie E Daws
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA; Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA.
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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] [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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DNA Damage Regulates the Functions of the RNA Binding Protein Sam68 through ATM-Dependent Phosphorylation. Cancers (Basel) 2022; 14:cancers14163847. [PMID: 36010841 PMCID: PMC9405969 DOI: 10.3390/cancers14163847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/26/2022] [Accepted: 08/05/2022] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Alterations of the complex network of interactions between the DNA damage response pathway and RNA metabolism have been described in several tumors, and increasing efforts are devoted to the elucidation of the molecular mechanisms involved in this network. Previous large-scale proteomic studies identified the RNA binding protein Sam68 as a putative target of the ATM kinase. Herein, we demonstrate that ATM phosphorylates Sam68 upon DNA damage induction, and this post-translational modification regulates both the signaling function of Sam68 in the initial phase of the DNA damage response and its RNA processing activity. Thus, our study uncovers anew crosstalk between ATM and Sam68, which may represent a paradigm for the functional interaction between the DDR pathway and RNA binding proteins, and a possible actionabletarget in human cancers. Abstract Cancer cells frequently exhibit dysregulation of the DNA damage response (DDR), genomic instability, and altered RNA metabolism. Recent genome-wide studies have strongly suggested an interaction between the pathways involved in the cellular response to DDR and in the regulation of RNA metabolism, but the molecular mechanism(s) involved in this crosstalk are largely unknown. Herein, we found that activation of the DDR kinase ATM promotes its interaction with Sam68, leading to phosphorylation of this multifunctional RNA binding protein (RBP) on three residues: threonine 61, serine 388 and serine 390. Moreover, we demonstrate that ATM-dependent phosphorylation of threonine 61 promotes the function of Sam68 in the DDR pathway and enhances its RNA processing activity. Importantly, ATM-mediated phosphorylation of Sam68 in prostate cancer cells modulates alternative polyadenylation of transcripts that are targets of Sam68, supporting the notion that the ATM–Sam68 axis exerts a multifaceted role in the response to DNA damage. Thus, our work validates Sam68 as an ATM kinase substrate and uncovers an unexpected bidirectional interplay between ATM and Sam68, which couples the DDR pathway to modulation of RNA metabolism in response to genotoxic stress.
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Naro C, Barbagallo F, Caggiano C, De Musso M, Panzeri V, Di Agostino S, Paronetto MP, Sette C. Functional Interaction Between the Oncogenic Kinase NEK2 and Sam68 Promotes a Splicing Program Involved in Migration and Invasion in Triple-Negative Breast Cancer. Front Oncol 2022; 12:880654. [PMID: 35530315 PMCID: PMC9068942 DOI: 10.3389/fonc.2022.880654] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 03/16/2022] [Indexed: 12/01/2022] Open
Abstract
Triple-negative breast cancer (TNBC) represents the most aggressive breast cancer subtype. Poor prognosis in TNBC is partly due to lack of efficacious targeted therapy and high propensity to metastasize. Dysregulation of alternative splicing has recently emerged as a trait of TNBC, suggesting that unveiling the molecular mechanisms underlying its regulation could uncover new druggable cancer vulnerabilities. The oncogenic kinase NEK2 is significantly upregulated in TNBC and contributes to shaping their unique splicing profile. Herein, we found that NEK2 interacts with the RNA binding protein Sam68 in TNBC cells and that NEK2-mediated phosphorylation of Sam68 enhances its splicing activity. Genome-wide transcriptome analyses identified the splicing targets of Sam68 in TNBC cells and revealed a common set of exons that are co-regulated by NEK2. Functional annotation of splicing-regulated genes highlighted cell migration and spreading as biological processes regulated by Sam68. Accordingly, Sam68 depletion reduces TNBC cell migration and invasion, and these effects are potentiated by the concomitant inhibition of NEK2 activity. Our findings indicate that Sam68 and NEK2 functionally cooperate in the regulation of a splicing program that sustains the pro-metastatic features of TNBC cells.
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Affiliation(s)
- Chiara Naro
- Department of Neuroscience, Section of Human Anatomy, University of the Sacred Hearth, Rome, Italy.,Gemelli SCIENCE and TECHNOLOGY PARK (GSTeP)-Organoids Research Core Facility, Fondazione Policlinico Agostino Gemelli IRCCS, Rome, Italy
| | - Federica Barbagallo
- Department of Experimental Medicine, University of Rome Sapienza, Rome, Italy
| | - Cinzia Caggiano
- Department of Neuroscience, Section of Human Anatomy, University of the Sacred Hearth, Rome, Italy.,Gemelli SCIENCE and TECHNOLOGY PARK (GSTeP)-Organoids Research Core Facility, Fondazione Policlinico Agostino Gemelli IRCCS, Rome, Italy
| | - Monica De Musso
- Department of Neuroscience, Section of Human Anatomy, University of the Sacred Hearth, Rome, Italy
| | - Valentina Panzeri
- Department of Neuroscience, Section of Human Anatomy, University of the Sacred Hearth, Rome, Italy.,Gemelli SCIENCE and TECHNOLOGY PARK (GSTeP)-Organoids Research Core Facility, Fondazione Policlinico Agostino Gemelli IRCCS, Rome, Italy
| | - Silvia Di Agostino
- Department of Health Sciences, "Magna Graecia" University of Catanzaro, Catanzaro, Italy
| | - Maria Paola Paronetto
- Department of Movement, Human and Health Sciences, University of Rome Foro Italico, Rome, Italy.,Laboratory of Molecular and Cellular Neurobiology, Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Claudio Sette
- Department of Neuroscience, Section of Human Anatomy, University of the Sacred Hearth, Rome, Italy.,Gemelli SCIENCE and TECHNOLOGY PARK (GSTeP)-Organoids Research Core Facility, Fondazione Policlinico Agostino Gemelli IRCCS, Rome, Italy
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8
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Palombo R, Paronetto MP. pncCCND1_B Engages an Inhibitory Protein Network to Downregulate CCND1 Expression upon DNA Damage. Cancers (Basel) 2022; 14:cancers14061537. [PMID: 35326688 PMCID: PMC8946712 DOI: 10.3390/cancers14061537] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 03/09/2022] [Accepted: 03/14/2022] [Indexed: 11/16/2022] Open
Abstract
Promoter-associated noncoding RNAs (pancRNAs) represent a class of noncoding transcripts driven from the promoter region of protein-coding or non-coding genes that operate as cis-acting elements to regulate the expression of the host gene. PancRNAs act by altering the chromatin structure and recruiting transcription regulators. PncCCND1_B is driven by the promoter region of CCND1 and regulates CCND1 expression in Ewing sarcoma through recruitment of a multi-molecular complex composed of the RNA binding protein Sam68 and the DNA/RNA helicase DHX9. In this study, we investigated the regulation of CCND1 expression in Ewing sarcoma cells upon exposure to chemotherapeutic drugs. Pan-inhibitor screening indicated that etoposide, a drug used for Ewing sarcoma treatment, promotes transcription of pncCCND1_B and repression of CCND1 expression. RNA immunoprecipitation experiments showed increased binding of Sam68 to the pncCCND1_B after treatment, despite the significant reduction in DHX9 protein. This effect was associated with the formation of DNA:RNA duplexes at the CCND1 promoter. Furthermore, Sam68 interacted with HDAC1 in etoposide treated cells, thus contributing to chromatin remodeling and epigenetic changes. Interestingly, inhibition of the ATM signaling pathway by KU 55,933 treatment was sufficient to inhibit etoposide-induced Sam68-HDAC1 interaction without rescuing DHX9 expression. In these conditions, the DNA:RNA hybrids persist, thus contributing to the local chromatin inactivation at the CCND1 promoter region. Altogether, our results show an active role of Sam68 in DNA damage signaling and chromatin remodeling on the CCND1 gene by fine-tuning transitions of epigenetic complexes on the CCND1 promoter.
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Affiliation(s)
- Ramona Palombo
- Laboratory of Molecular and Cellular Neurobiology, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy;
| | - Maria Paola Paronetto
- Laboratory of Molecular and Cellular Neurobiology, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy;
- Department of Movement, Human and Health Sciences, University of Rome “Foro Italico”, Piazza Lauro de Bosis, 15, 00135 Rome, Italy
- Correspondence:
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Comparative O-GlcNAc Proteomic Analysis Reveals a Role of O-GlcNAcylated SAM68 in Lung Cancer Aggressiveness. Cancers (Basel) 2022; 14:cancers14010243. [PMID: 35008409 PMCID: PMC8749979 DOI: 10.3390/cancers14010243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/19/2021] [Accepted: 12/30/2021] [Indexed: 01/25/2023] Open
Abstract
Simple Summary Lung cancer claims the most lives annually among cancers; to date, invasion and metastasis still pose challenges to effective treatment. O-GlcNAcylation, an enzymatic modification of proteins after biosynthesis, modulates the functions of many proteins. Aberrant O-GlcNAcylation is linked to pathogenic mechanisms of cancer, including invasion and metastasis. However, little is known about the profile of O-GlcNAcylated proteins involved in cancer aggressiveness. Here, by comparing profiles of O-GlcNAcylated proteins from two lung cancer cell lines different in their invasive potential, we identified candidates for O-GlcNAcylated proteins that may be involved in cancer aggressiveness. One of these candidates, SAM68, was further characterized. Results confirmed O-GlcNAcylation of SAM68; functional analyses on SAM68 with mutations at O-GlcNAcylation sites suggested a role of O-GlcNAcylated SAM68 in modulating lung cancer cell migration/invasion. Future elucidation of the functional significance of differential O-GlcNAcylation of proteins identified in this study may provide new insights into mechanisms of lung cancer progression. Abstract O-GlcNAcylation is a reversible and dynamic post-translational protein modification catalyzed by O-GlcNAc transferase (OGT). Despite the reported association of O-GlcNAcylation with cancer metastasis, the O-GlcNAc proteome profile for cancer aggressiveness remains largely uncharacterized. Here, we report our comparative O-GlcNAc proteome profiling of two differentially invasive lung adenocarcinoma cell lines, which identified 158 down-regulated and 106 up-regulated candidates in highly invasive cells. Among these differential proteins, a nuclear RNA-binding protein, SAM68 (SRC associated in mitosis of 68 kDa), was further investigated. Results showed that SAM68 is O-GlcNAcylated and may interact with OGT in the nucleus. Eleven O-GlcNAcylation sites were identified, and data from mutant analysis suggested that multiple serine residues in the N-terminal region are important for O-GlcNAcylation and the function of SAM68 in modulating cancer cell migration and invasion. Analysis of clinical specimens found that high SAM68 expression was associated with late cancer stages, and patients with high-OGT/high-SAM68 expression in their tumors had poorer overall survival compared to those with low-OGT/low-SAM68 expression. Our study revealed an invasiveness-associated O-GlcNAc proteome profile and connected O-GlcNAcylated SAM68 to lung cancer aggressiveness.
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Kazemi-Lomedasht F, Karami E. Biosensors: Types, features, and application in biomedicine. Asian Pac J Trop Biomed 2022. [DOI: 10.4103/2221-1691.354427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Goodman WA, Basavarajappa SC, Liu AR, Rodriguez FDS, Mathes T, Ramakrishnan P. Sam68 contributes to intestinal inflammation in experimental and human colitis. Cell Mol Life Sci 2021; 78:7635-7648. [PMID: 34693458 PMCID: PMC8817240 DOI: 10.1007/s00018-021-03976-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 09/29/2021] [Accepted: 10/09/2021] [Indexed: 12/25/2022]
Abstract
Sam68 is an RNA-binding protein with an adaptor role in signal transduction. Our previous work identified critical proinflammatory and apoptotic functions for Sam68, downstream of the TNF/TNFR1 and TLR2/3/4 pathways. Recent studies have shown elevated Sam68 in inflamed tissues from rheumatoid arthritis and ulcerative colitis (UC) patients, suggesting that Sam68 contributes to chronic inflammatory diseases. Here, we hypothesized that deletion of Sam68 is protective against experimental colitis in vivo, via reductions in TNF-associated inflammatory signaling. We used Sam68 knockout (KO) mice to study the role of Sam68 in experimental colitis, including its contributions to TNF-induced inflammatory gene expression in three-dimensional intestinal organoid cultures. We also studied the expression of Sam68 and inflammatory genes in colon tissues of UC patients. Sam68 KO mice treated with an acute course of DSS exhibited significantly less weight loss and histopathological inflammation compared to wild-type controls, suggesting that Sam68 contributes to experimental colitis. Bone marrow transplants showed no pathologic role for hematopoietic cell-specific Sam68, suggesting that non-hematopoietic Sam68 drives intestinal inflammation. Gene expression analyses showed that Sam68 deficiency reduced the expression of proinflammatory genes in colon tissues from DSS-treated mice, as well as TNF-treated three-dimensional colonic organoids. We also found that inflammatory genes, such as TNF, CCR2, CSF2, IL33 and CXCL10, as well as Sam68 protein, were upregulated in inflamed colon tissues of UC patients. This report identifies Sam68 as an important inflammatory driver in response to intestinal epithelial damage, suggesting that targeting Sam68 may hold promise to treat UC patients.
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Affiliation(s)
- Wendy A Goodman
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 2103 Cornell Road, Room 6526, Wolstein Research Building, Cleveland, OH, 44106, USA
| | - Shrikanth C Basavarajappa
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 2103 Cornell Road, Room 6526, Wolstein Research Building, Cleveland, OH, 44106, USA
| | - Angela R Liu
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 2103 Cornell Road, Room 6526, Wolstein Research Building, Cleveland, OH, 44106, USA
| | - Franklin D Staback Rodriguez
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 2103 Cornell Road, Room 6526, Wolstein Research Building, Cleveland, OH, 44106, USA
| | - Tailor Mathes
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 2103 Cornell Road, Room 6526, Wolstein Research Building, Cleveland, OH, 44106, USA
| | - Parameswaran Ramakrishnan
- Department of Pathology, School of Medicine, Case Western Reserve University and University Hospitals Cleveland Medical Center, 2103 Cornell Road, Room 6526, Wolstein Research Building, Cleveland, OH, 44106, USA.
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
- The Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
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12
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Zheng C, Lu T, Fan Z. miR-200b-3p alleviates TNF-α-induced apoptosis and inflammation of intestinal epithelial cells and ulcerative colitis progression in rats via negatively regulating KHDRBS1. Cytotechnology 2021; 73:727-743. [PMID: 34629748 DOI: 10.1007/s10616-021-00490-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 08/18/2021] [Indexed: 12/20/2022] Open
Abstract
Ulcerative colitis (UC) is difficult to be treated. miRNAs are a group of gene regulators. Study demonstrated that miR-200b-3p is involved in the development of UC, but the specific molecular mechanism is still unclear. A UC model was established by injecting acetic acid into rectum of rats, which were then treated with miR-200b-3p antagonists and agonists. Weight change, fecal viscosity and fecal bleeding were measured to determine disease activity index. The ratio of colon length to weight was measured. Colon lesions were detected by H&E staining. ELISA was used to detect the expression of TGF-β in colon tissues and IL-10/CRP in serum. Intestinal epithelial cells (NCM460) were treated by TNF-α to create an inflammatory environment. MRNA and protein levels of miR-200b-3p, KHDRBS1, IL-10, IL-6, IL-1β, TGF-β, Bcl-2, Bax and C-capase-3 were detected by qRT-PCR and Western blot, respectively. TargetScan database and dual-luciferase reporter assay were conducted to predict the targeting relationship between miR-200b-3p and KHDRBS1. MTT and flow cytometry were respectively performed to detect cell proliferation and apoptosis. MiR-200b-3p expression was inhibited, leading to increased disease activity index and colonic length-weight ratio, and aggravation of lesions of the UC rat model. Up-regulation of miR-200b-3p can relieve inflammation and apoptosis of immune cells in UC rats. MiR-200b-3p targeted KHDRBS1 and inhibited its expression. Moreover, KHDRBS1 reversed the effects of miR-200b-3p on apoptosis, proliferation and inflammation of intestinal epithelial cells. MiR-200b-3p alleviates UC by negatively regulating KHDRBS1.
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Affiliation(s)
- Chunju Zheng
- Department of Anorectal, Huai'an TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Huai'an, China
| | - Ting Lu
- Department of Anorectal, Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, 157 Daming Road, Qinhuai District, Nanjing, 210001 Jiangsu China
| | - Zhimin Fan
- Department of Anorectal, Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, 157 Daming Road, Qinhuai District, Nanjing, 210001 Jiangsu China
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13
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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] [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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14
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Qiao A, Zhou J, Xu S, Ma W, Boriboun C, Kim T, Yan B, Deng J, Yang L, Zhang E, Song Y, Ma YC, Richard S, Zhang C, Qiu H, Habegger KM, Zhang J, Qin G. Sam68 promotes hepatic gluconeogenesis via CRTC2. Nat Commun 2021; 12:3340. [PMID: 34099657 PMCID: PMC8185084 DOI: 10.1038/s41467-021-23624-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 05/05/2021] [Indexed: 02/07/2023] Open
Abstract
Hepatic gluconeogenesis is essential for glucose homeostasis and also a therapeutic target for type 2 diabetes, but its mechanism is incompletely understood. Here, we report that Sam68, an RNA-binding adaptor protein and Src kinase substrate, is a novel regulator of hepatic gluconeogenesis. Both global and hepatic deletions of Sam68 significantly reduce blood glucose levels and the glucagon-induced expression of gluconeogenic genes. Protein, but not mRNA, levels of CRTC2, a crucial transcriptional regulator of gluconeogenesis, are >50% lower in Sam68-deficient hepatocytes than in wild-type hepatocytes. Sam68 interacts with CRTC2 and reduces CRTC2 ubiquitination. However, truncated mutants of Sam68 that lack the C- (Sam68ΔC) or N-terminal (Sam68ΔN) domains fails to bind CRTC2 or to stabilize CRTC2 protein, respectively, and transgenic Sam68ΔN mice recapitulate the blood-glucose and gluconeogenesis profile of Sam68-deficient mice. Hepatic Sam68 expression is also upregulated in patients with diabetes and in two diabetic mouse models, while hepatocyte-specific Sam68 deficiencies alleviate diabetic hyperglycemia and improves insulin sensitivity in mice. Thus, our results identify a role for Sam68 in hepatic gluconeogenesis, and Sam68 may represent a therapeutic target for diabetes. Hepatic gluconeogenesis is important for glucose homeostasis and a therapeutic target for type 2 diabetes. Here, the authors show that the RNA-binding adaptor protein Sam68 promotes the expression level of gluconeogenic genes and increases blood glucose levels by stabilizing the transcriptional coactivator CRTC2, while hepatic Sam68 deletion alleviates hyperglycemia in mice.
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Affiliation(s)
- Aijun Qiao
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Junlan Zhou
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Shiyue Xu
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Wenxia Ma
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Chan Boriboun
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Teayoun Kim
- Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, School of Medicine, Birmingham, AL, USA
| | - Baolong Yan
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Jianxin Deng
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Liu Yang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Eric Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Yuhua Song
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Yongchao C Ma
- Departments of Pediatrics, Neurology and Physiology, Northwestern University Feinberg School of Medicine, Anne & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Stephane Richard
- Lady Davis Institute for Medical Research, McGill University, Montreal, QC, Canada
| | - Chunxiang Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Hongyu Qiu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science Georgia State University, Atlanta, GA, USA
| | - Kirk M Habegger
- Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, School of Medicine, Birmingham, AL, USA
| | - Jianyi Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Gangjian Qin
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA. .,Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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15
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Chorostecki U, Saus E, Gabaldón T. Structural characterization of NORAD reveals a stabilizing role of spacers and two new repeat units. Comput Struct Biotechnol J 2021; 19:3245-3254. [PMID: 34141143 PMCID: PMC8192489 DOI: 10.1016/j.csbj.2021.05.045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/25/2021] [Accepted: 05/25/2021] [Indexed: 12/19/2022] Open
Abstract
Long non-coding RNAs (lncRNAs) can perform a variety of key cellular functions by interacting with proteins and other RNAs. Recent studies have shown that the functions of lncRNAS are largely mediated by their structures. However, our structural knowledge for most lncRNAS is limited to sequence-based computational predictions. Non-coding RNA activated by DNA damage (NORAD) is an atypical lncRNA due to its abundant expression and high sequence conservation. NORAD regulates genomic stability by interacting with proteins and microRNAs. Previous sequence-based characterization has identified a modular organization of NORAD composed of several NORAD repeat units (NRUs). These units comprise the protein-binding elements and are separated by regular spacers. Here, we experimentally determine for the first time the secondary structure of NORAD using the nextPARS approach. Our results suggest that the spacer regions provide structural stability to NRUs. Furthermore, we uncover two previously unreported NRUs, and determine the core structural motifs conserved across NRUs. Overall, these findings will help to elucidate the function and evolution of NORAD.
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Affiliation(s)
- Uciel Chorostecki
- Barcelona Supercomputing Centre (BSC-CNS). Jordi Girona, 29. 08034 Barcelona, Spain.,Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain
| | - Ester Saus
- Barcelona Supercomputing Centre (BSC-CNS). Jordi Girona, 29. 08034 Barcelona, Spain.,Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain
| | - Toni Gabaldón
- Barcelona Supercomputing Centre (BSC-CNS). Jordi Girona, 29. 08034 Barcelona, Spain.,Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain.,Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
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16
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Leptin, Leptin Receptor, KHDRBS1 (KH RNA Binding Domain Containing, Signal Transduction Associated 1), and Adiponectin in Bone Metastasis from Breast Carcinoma: An Immunohistochemical Study. Biomedicines 2020; 8:biomedicines8110510. [PMID: 33213024 PMCID: PMC7698510 DOI: 10.3390/biomedicines8110510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/09/2020] [Accepted: 11/12/2020] [Indexed: 02/07/2023] Open
Abstract
Breast cancer patients are at a high risk of complications from bone metastasis. Molecular characterization of bone metastases is essential for the discovery of new therapeutic targets. Here, we investigated the expression and the intracellular distribution of KH RNA binding domain containing, signal transduction associated 1 (KHDRBS1), leptin, leptin receptor (LEPR), and adiponectin in bone metastasis from breast carcinoma and looked for correlations between the data. The expression of these proteins is known in breast carcinoma, but it has not been investigated in bone metastatic tissue to date. Immunohistochemical analysis was carried out on bone metastasis specimens, then semiquantitative evaluation of the results and the Pearson test were performed to determine eventual correlations. KHDRBS1 expression was significantly higher in the nuclei than in the cytosol of metastatic cells; LEPR was prevalently observed in the cytosol and the nuclei; leptin and adiponectin were found in metastatic cells and stromal cells; the strongest positive correlation was between nuclear KHDRBS1 and nuclear LEPR expression. Taken together, our findings support the importance of the leptin/LEPR/KHDRBS1 axis and of adiponectin in the progression of bone metastasis and suggest their potential application in pharmacological interventions.
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17
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De Paola E, Forcina L, Pelosi L, Pisu S, La Rosa P, Cesari E, Nicoletti C, Madaro L, Mercatelli N, Biamonte F, Nobili A, D'Amelio M, De Bardi M, Volpe E, Caporossi D, Sette C, Musarò A, Paronetto MP. Sam68 splicing regulation contributes to motor unit establishment in the postnatal skeletal muscle. Life Sci Alliance 2020; 3:3/10/e201900637. [PMID: 32753528 PMCID: PMC7409371 DOI: 10.26508/lsa.201900637] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 07/23/2020] [Accepted: 07/24/2020] [Indexed: 01/08/2023] Open
Abstract
Sam68 ensures the establishment of neuromuscular junctions (NMJs) and motor unit integrity by orchestrating a neuronal splicing program. RNA-binding proteins orchestrate the composite life of RNA molecules and impact most physiological processes, thus underlying complex phenotypes. The RNA-binding protein Sam68 regulates differentiation processes by modulating splicing, polyadenylation, and stability of select transcripts. Herein, we found that Sam68−/− mice display altered regulation of alternative splicing in the spinal cord of key target genes involved in synaptic functions. Analysis of the motor units revealed that Sam68 ablation impairs the establishment of neuromuscular junctions and causes progressive loss of motor neurons in the spinal cord. Importantly, alterations of neuromuscular junction morphology and properties in Sam68−/− mice correlate with defects in muscle and motor unit integrity. Sam68−/− muscles display defects in postnatal development, with manifest signs of atrophy. Furthermore, fast-twitch muscles in Sam68−/− mice show structural features typical of slow-twitch muscles, suggesting alterations in the metabolic and functional properties of myofibers. Collectively, our data identify a key role for Sam68 in muscle development and suggest that proper establishment of motor units requires timely expression of synaptic splice variants.
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Affiliation(s)
- Elisa De Paola
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy.,IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Laura Forcina
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Laura Pelosi
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Simona Pisu
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Piergiorgio La Rosa
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Eleonora Cesari
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy.,Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Heart, Rome, Italy
| | - Carmine Nicoletti
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Luca Madaro
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Heart, Rome, Italy
| | - Neri Mercatelli
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy.,IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Filippo Biamonte
- Institute of Biochemistry and Clinical Biochemistry, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Annalisa Nobili
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy.,Department of Medicine, University Campus-Biomedico, Rome, Italy
| | - Marcello D'Amelio
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy.,Department of Medicine, University Campus-Biomedico, Rome, Italy
| | - Marco De Bardi
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Elisabetta Volpe
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Daniela Caporossi
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy
| | - Claudio Sette
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy .,Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Heart, Rome, Italy
| | - Antonio Musarò
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Maria Paola Paronetto
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy .,IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
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18
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Sumithra B, Jayanthi VSPKSA, Manne HC, Gunda R, Saxena U, Das AB. Antibody-based biosensor to detect oncogenic splicing factor Sam68 for the diagnosis of lung cancer. Biotechnol Lett 2020; 42:2501-2509. [PMID: 32648188 DOI: 10.1007/s10529-020-02951-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 06/28/2020] [Indexed: 11/27/2022]
Abstract
OBJECTIVE The present work aimed to investigate the potential utility of Sam68 protein as a prognostic marker in lung cancer. Then an electrochemical immunosensor is fabricated that is sufficiently sensitive to detect Sam68. RESULTS Analysis of stage-specific Lung cancer microarray data shows that differential expression of Sam68 is associated with cancer stage and monotonically increases from early tumor stage to advanced metastatic stage. Moreover, the higher expression of Sam68 results in reduced survival of lung cancer patients. Based on these observations, an electrochemical immunosensor was developed for the quantification of Sam68 protein. The target protein was captured by the Anti-Sam68 antibody that was immobilized on the modified Glassy carbon electrode. The stepwise assembly process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. This fabricated immunosensor displayed good analytical performance in comparison to commercial ELISA kit with good sensitivity, lower detection limit (LOD) of 10.5 pg mL-1, and wide linear detection range from 1 to 5 μg mL-1. This method was validated with satisfactory detection of Sam68 protein in lung adenocarcinoma cell line, NCI-H23. Besides, spike and recovery assay reconfirm that the sensor can precisely quantify Sam68 protein in a complex physiological sample. CONCLUSION We conclude Sam68 as a valuable prognostic biomarker for early detection of lung cancer. Moreover, we report the first study on the development of an electrochemical immunosensor for the detection of Sam68. The fabricated immunosensor exhibit excellent analytical performance, which can accurately predict the lung cancer patient pathological state.
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Affiliation(s)
- B Sumithra
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | | | - Hari Chandana Manne
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | - Rashmika Gunda
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | - Urmila Saxena
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India.
| | - Asim Bikas Das
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India.
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19
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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] [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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20
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Sharma M, Sharma S, Alawada A. Understanding the binding specificities of mRNA targets by the mammalian Quaking protein. Nucleic Acids Res 2020; 47:10564-10579. [PMID: 31602485 PMCID: PMC6847458 DOI: 10.1093/nar/gkz877] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 09/18/2019] [Accepted: 10/08/2019] [Indexed: 01/01/2023] Open
Abstract
Mammalian Quaking (QKI) protein, a member of STAR family of proteins is a mRNA-binding protein, which post-transcriptionally modulates the target RNA. QKI protein possesses a maxi-KH domain composed of single heterogeneous nuclear ribonucleoprotein K homology (KH) domain and C-terminal QUA2 domain, that binds a sequence-specific QKI RNA recognition element (QRE), CUAAC. To understand the binding specificities for different mRNA sequences of the KH-QUA2 domain of QKI protein, we introduced point mutations at different positions in the QRE resulting in twelve different mRNA sequences with single nucleotide change. We carried out long unbiased molecular dynamics simulations using two different sets of recently updated forcefield parameters: AMBERff14SB+RNAχOL3 and CHARMM36 (with CMAP correction). We analyzed the changes in intermolecular dynamics as a result of mutation. Our results show that AMBER forcefields performed better to model the interactions between mRNA and protein. We also calculated the binding affinities of different mRNA sequences and found that the relative order correlates to the reported experimental studies. Our study shows that the favorable binding with the formation of stable complex will occur when there is an increase of the total intermolecular contacts between mRNA and protein, but without the loss of native contacts within the KH-QUA domain.
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Affiliation(s)
- Monika Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Sector 81, Knowledge City, SAS Nagar, Punjab, India
| | - Shakshi Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Sector 81, Knowledge City, SAS Nagar, Punjab, India
| | - Apoorv Alawada
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Sector 81, Knowledge City, SAS Nagar, Punjab, India
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21
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Pagliarini V, Jolly A, Bielli P, Di Rosa V, De la Grange P, Sette C. Sam68 binds Alu-rich introns in SMN and promotes pre-mRNA circularization. Nucleic Acids Res 2020; 48:633-645. [PMID: 31777926 PMCID: PMC6954450 DOI: 10.1093/nar/gkz1117] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 11/12/2019] [Accepted: 11/22/2019] [Indexed: 01/01/2023] Open
Abstract
The Spinal Muscular Atrophy (SMA) gene SMN was recently duplicated (SMN1 and SMN2) in higher primates. Furthermore, invasion of the locus by repetitive elements almost doubled its size with respect to mouse Smn, in spite of an almost identical protein-coding sequence. Herein, we found that SMN ranks among the human genes with highest density of Alus, which are evolutionary conserved in primates and often occur in inverted orientation. Inverted repeat Alus (IRAlus) negatively regulate splicing of long introns within SMN, while promoting widespread alternative circular RNA (circRNA) biogenesis. Bioinformatics analyses revealed the presence of ultra-conserved Sam68 binding sites in SMN IRAlus. Cross-link-immunoprecipitation (CLIP), mutagenesis and silencing experiments showed that Sam68 binds in proximity of intronic Alus in the SMN pre-mRNA, thus favouring circRNA biogenesis in vitro and in vivo. These findings highlight a novel layer of regulation in SMN expression, uncover the crucial impact exerted by IRAlus and reveal a role for Sam68 in SMN circRNA biogenesis.
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Affiliation(s)
- Vittoria Pagliarini
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Heart, Rome 00168, Italy.,Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome 00168, Italy
| | - Ariane Jolly
- GenoSplice Technology, iPEPS-ICM, Hôpital de la Pitié Salpêtrière, Paris 75013, France
| | - Pamela Bielli
- Laboratory of Neuroembryology, IRCCS Fondazione Santa Lucia, Rome 00143, Italy.,Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome 00133, Italy
| | - Valentina Di Rosa
- Laboratory of Neuroembryology, IRCCS Fondazione Santa Lucia, Rome 00143, Italy.,Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome 00133, Italy
| | - Pierre De la Grange
- GenoSplice Technology, iPEPS-ICM, Hôpital de la Pitié Salpêtrière, Paris 75013, France
| | - Claudio Sette
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Heart, Rome 00168, Italy.,Laboratory of Neuroembryology, IRCCS Fondazione Santa Lucia, Rome 00143, Italy
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22
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Maroni P. Leptin, Adiponectin, and Sam68 in Bone Metastasis from Breast Cancer. Int J Mol Sci 2020; 21:ijms21031051. [PMID: 32033341 PMCID: PMC7037668 DOI: 10.3390/ijms21031051] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 12/12/2022] Open
Abstract
The most serious aspect of neoplastic disease is the spread of cancer cells to secondary sites. Skeletal metastases can escape detection long after treatment of the primary tumour and follow-up. Bone tissue is a breeding ground for many types of cancer cells, especially those derived from the breast, prostate, and lung. Despite advances in diagnosis and therapeutic strategies, bone metastases still have a profound impact on quality of life and survival and are often responsible for the fatal outcome of the disease. Bone and the bone marrow environment contain a wide variety of cells. No longer considered a passive filler, bone marrow adipocytes have emerged as critical contributors to cancer progression. Released by adipocytes, adipokines are soluble factors with hormone-like functions and are currently believed to affect tumour development. Src-associated in mitosis of 68 kDa (Sam68), originally discovered as a protein physically associated with and phosphorylated by c-Src during mitosis, is now recognised as an important RNA-binding protein linked to tumour onset and progression of disease. Sam68 also regulates splicing events and recent evidence reports that dysregulation of these events is a key step in neoplastic transformation and tumour progression. The present review reports recent findings on adipokines and Sam68 and their role in breast cancer progression and metastasis.
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Affiliation(s)
- Paola Maroni
- IRCCS Istituto Ortopedico Galeazzi, Via R. Galeazzi 4, 20161 Milano, Italy
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23
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Kilchert C, Sträßer K, Kunetsky V, Änkö ML. From parts lists to functional significance-RNA-protein interactions in gene regulation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 11:e1582. [PMID: 31883228 DOI: 10.1002/wrna.1582] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 12/03/2019] [Accepted: 12/07/2019] [Indexed: 12/17/2022]
Abstract
Hundreds of canonical RNA binding proteins facilitate diverse and essential RNA processing steps in cells forming a central regulatory point in gene expression. However, recent discoveries including the identification of a large number of noncanonical proteins bound to RNA have changed our view on RNA-protein interactions merely as necessary steps in RNA biogenesis. As the list of proteins interacting with RNA has expanded, so has the scope of regulation through RNA-protein interactions. In addition to facilitating RNA metabolism, RNA binding proteins help to form subcellular structures and membraneless organelles, and provide means to recruit components of macromolecular complexes to their sites of action. Moreover, RNA-protein interactions are not static in cells but the ribonucleoprotein (RNP) complexes are highly dynamic in response to cellular cues. The identification of novel proteins in complex with RNA and ways cells use these interactions to control cellular functions continues to broaden the scope of RNA regulation in cells and the current challenge is to move from cataloguing the components of RNPs into assigning them functions. This will not only facilitate our understanding of cellular homeostasis but may bring in key insights into human disease conditions where RNP components play a central role. This review brings together the classical view of regulation accomplished through RNA-protein interactions with the novel insights gained from the identification of RNA binding interactomes. We discuss the challenges in combining molecular mechanism with cellular functions on the journey towards a comprehensive understanding of the regulatory functions of RNA-protein interactions in cells. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications aRNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition.
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Affiliation(s)
- Cornelia Kilchert
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Katja Sträßer
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Vladislav Kunetsky
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Minna-Liisa Änkö
- Centre for Reproductive Health and Centre for Cancer Research, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.,Department of Molecular and Translational Science, School of Clinical Sciences, Monash University, Melbourne, Victoria, Australia
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24
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Subramania S, Gagné LM, Campagne S, Fort V, O'Sullivan J, Mocaer K, Feldmüller M, Masson JY, Allain FHT, Hussein SM, Huot MÉ. SAM68 interaction with U1A modulates U1 snRNP recruitment and regulates mTor pre-mRNA splicing. Nucleic Acids Res 2019; 47:4181-4197. [PMID: 30767021 PMCID: PMC6486544 DOI: 10.1093/nar/gkz099] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/14/2019] [Accepted: 02/05/2019] [Indexed: 12/11/2022] Open
Abstract
Src associated in mitosis (SAM68) plays major roles in regulating RNA processing events, such as alternative splicing and mRNA translation, implicated in several developmental processes. It was previously shown that SAM68 regulates the alternative splicing of the mechanistic target of rapamycin (mTor), but the mechanism regulating this process remains elusive. Here, we report that SAM68 interacts with U1 small nuclear ribonucleoprotein (U1 snRNP) to promote splicing at the 5′ splice site in intron 5 of mTor. We also show that this direct interaction is mediated through U1A, a core-component of U1snRNP. SAM68 was found to bind the RRM1 domain of U1A through its C-terminal tyrosine rich region (YY domain). Deletion of the U1A-SAM68 interaction domain or mutation in SAM68-binding sites in intron 5 of mTor abrogates U1A recruitment and 5′ splice site recognition by the U1 snRNP, leading to premature intron 5 termination and polyadenylation. Taken together, our results provide the first mechanistic study by which SAM68 modulates alternative splicing decision, by affecting U1 snRNP recruitment at 5′ splice sites.
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Affiliation(s)
- Suryasree Subramania
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Laurence M Gagné
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Sébastien Campagne
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Victoire Fort
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Julia O'Sullivan
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Karel Mocaer
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada
| | - Miki Feldmüller
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Jean-Yves Masson
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Frédéric H T Allain
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Samer M Hussein
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Marc-Étienne Huot
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
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25
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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: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [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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26
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Chen Y, Zhang L, Liu S, Yao B, Zhang H, Liang S, Ma J, Liang X, Shi W. Sam68 mediates high glucose‑induced podocyte apoptosis through modulation of Bax/Bcl‑2. Mol Med Rep 2019; 20:3728-3734. [PMID: 31485651 PMCID: PMC6755155 DOI: 10.3892/mmr.2019.10601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 03/20/2019] [Indexed: 02/06/2023] Open
Abstract
Hyperglycemia promotes podocyte apoptosis and contributes to the pathogenesis of diabetic nephropathy (DN). However, the mechanisms of hyperglycemia-induced podocyte apoptosis remain unknown. Recent studies have implicated Src-associated substrate during mitosis of 68 kDa (Sam68) in various cellular processes including RNA metabolism, apoptosis, signal transduction. This study sought to examine the effect of Sam68 on high glucose (HG)-induced podocytes apoptosis, and the mechanism underlying this effect. Immortalized mouse podocytes were exposed to medium containing normal glucose, or HG and Sam68 siRNA, respectively. The expression of Sam68 in podocytes was determined by fluorescence quantitative PCR (qPCR), immunofluorescence and immunoblotting. The role of Sam68 in HG-induced podocyte apoptosis was further evaluated by inhibiting Sam68 expression by Sam68 siRNA and performing flow cytometry. The mRNA and protein expression of pro-apoptosis gene Bax and anti-apoptotic gene Bcl-2 were assessed by qRCR and immunoblotting. In the present study, it was first demonstrated that Sam68 was upregulated in a time and dose-dependent manner in in vitro HG-treated podocytes. Pretreatment with Sam68 siRNA markedly decreased nuclear Sam68 expression. Moreover, the effects of HG-induced apoptosis were also abrogated by Sam68 knockdown in cultured podocytes. Furthermore, HG increased Bax and decreased Bcl-2 protein expression in cultured podocytes, and this effect was blocked by Sam68 knockdown. The results of the present study revealed that Sam68 mediated HG-induced podocyte apoptosis, probably through the Bax/Bcl-2 signaling pathway, and thus may be a potential therapeutic target for DN.
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Affiliation(s)
- Yuyu Chen
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Li Zhang
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangzhou, Guangdong 510080, P.R. China
| | - Shuangxin Liu
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangzhou, Guangdong 510080, P.R. China
| | - Binfeng Yao
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangzhou, Guangdong 510080, P.R. China
| | - Hong Zhang
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangzhou, Guangdong 510080, P.R. China
| | - Shun Liang
- Division of Nephrology, Yue Bei People's Hospital, Shaoguan, Guangdong 512025, P.R. China
| | - Jianchao Ma
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangzhou, Guangdong 510080, P.R. China
| | - Xinling Liang
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangzhou, Guangdong 510080, P.R. China
| | - Wei Shi
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatrics Institute, Guangzhou, Guangdong 510080, P.R. China
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27
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Sumithra B, Saxena U, Das AB. A comprehensive study on genome-wide coexpression network of KHDRBS1/Sam68 reveals its cancer and patient-specific association. Sci Rep 2019; 9:11083. [PMID: 31366900 PMCID: PMC6668649 DOI: 10.1038/s41598-019-47558-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 07/19/2019] [Indexed: 12/11/2022] Open
Abstract
Human KHDRBS1/Sam68 is an oncogenic splicing factor involved in signal transduction and pre-mRNA splicing. We explored the molecular mechanism of KHDRBS1 to be a prognostic marker in four different cancers. Within specific cancer, including kidney renal papillary cell carcinoma (KIRP), lung adenocarcinoma (LUAD), acute myeloid leukemia (LAML), and ovarian cancer (OV), KHDRBS1 expression is heterogeneous and patient specific. In KIRP and LUAD, higher expression of KHDRBS1 affects the patient survival, but not in LAML and OV. Genome-wide coexpression analysis reveals genes and transcripts which are coexpressed with KHDRBS1 in KIRP and LUAD, form the functional modules which are majorly involved in cancer-specific events. However, in case of LAML and OV, such modules are absent. Irrespective of the higher expression of KHDRBS1, the significant divergence of its biological roles and prognostic value is due to its cancer-specific interaction partners and correlation networks. We conclude that rewiring of KHDRBS1 interactions in cancer is directly associated with patient prognosis.
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Affiliation(s)
- B Sumithra
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, 506004, Telangana, India
| | - Urmila Saxena
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, 506004, Telangana, India
| | - Asim Bikas Das
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, 506004, Telangana, India.
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28
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Groves JA, Gillman C, DeLay CN, Kroll TT. Identification of Novel Binding Partners for Transcription Factor Emx2. Protein J 2019; 38:2-11. [PMID: 30628007 DOI: 10.1007/s10930-019-09810-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The mammalian homolog of Drosophila empty spiracles 2 (Emx2) is a homeobox transcription factor that plays central roles in early development of the inner ear, pelvic and shoulder girdles, cerebral cortex, and urogenital organs. The role for Emx2 is best understood within the context of the development of the neocortical region of the cortex, where Emx2 is expressed in a high posterior-medial to low anterior-lateral gradient that regulates the partitioning of the neocortex into different functional fields that perform discrete computational tasks. Despite several lines of evidence demonstrating an Emx2 concentration-dependent mechanism for establishing functional areas within the developing neocortex, little is known about how Emx2 physically carries out this role. Although several binding partners for Emx2 have been identified (including Sp8, eIF4E, and Pbx1), no screens have been used to identify potential protein binding partners for this protein. We utilized a yeast two-hybrid screen using a library constructed from embryonic mouse cDNA in an attempt to identify novel binding partners for Emx2. This initial screen isolated two potential Emx2-binding partner proteins, Cnot6l and QkI-7. These novel Emx2-binding proteins are involved in multiple levels of mRNA metabolism that including splicing, mRNA export, translation, and destruction, thus making them interesting targets for further study.
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Affiliation(s)
- Jennifer A Groves
- Department of Chemistry, Central Washington University, 400 E. University Way, Ellensburg, WA, 98929-7539, USA
| | - Cody Gillman
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 157 Broad Center, M/C, Pasadena, USA
| | - Cierra N DeLay
- Department of Chemistry, Central Washington University, 400 E. University Way, Ellensburg, WA, 98929-7539, USA
| | - Todd T Kroll
- Department of Chemistry, Central Washington University, 400 E. University Way, Ellensburg, WA, 98929-7539, USA.
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29
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The RNA binding protein Sam68 controls T helper 1 differentiation and anti-mycobacterial response through modulation of miR-29. Cell Death Differ 2018; 26:1169-1180. [PMID: 30258098 DOI: 10.1038/s41418-018-0201-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 08/08/2018] [Accepted: 08/27/2018] [Indexed: 12/24/2022] Open
Abstract
Polarization of naive T cells into interferon (IFN)-γ-producing T helper 1 (Th1) cells is an essential event in the inflammatory response to pathogens. Herein, we identify the RNA binding protein Sam68 as a specific modulator of Th1 differentiation. Sam68-knockout (ko) naive T cells are strongly defective in IL-12-mediated Th1 polarization and express low levels of T-bet and Eomes. Consequently, Sam68-ko Th1 cells are significantly impaired in IFN-γ production. Moreover, we found that Sam68 is required for the induction of an inflammatory Th1 response during Mycobacterium bovis Bacillus Calmette-Guerin (BCG) infection, thus limiting bacterial dissemination in the lungs. Mechanistically, Sam68 directly binds to the microRNA miR-29, a negative regulator of Th1 response, and inhibits its expression during BCG infection. These findings uncover a novel post-transcriptional mechanism required for the Th1-mediated defense against intracellular pathogens and identify a new function for Sam68 in the regulation of the immune response.
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30
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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: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [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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31
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Narcís JO, Tapia O, Tarabal O, Piedrafita L, Calderó J, Berciano MT, Lafarga M. Accumulation of poly(A) RNA in nuclear granules enriched in Sam68 in motor neurons from the SMNΔ7 mouse model of SMA. Sci Rep 2018; 8:9646. [PMID: 29941967 PMCID: PMC6018117 DOI: 10.1038/s41598-018-27821-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 06/11/2018] [Indexed: 01/07/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a severe motor neuron (MN) disease caused by the deletion or mutation of the survival motor neuron 1 (SMN1) gene, which results in reduced levels of the SMN protein and the selective degeneration of lower MNs. The best-known function of SMN is the biogenesis of spliceosomal snRNPs, the major components of the pre-mRNA splicing machinery. Therefore, SMN deficiency in SMA leads to widespread splicing abnormalities. We used the SMN∆7 mouse model of SMA to investigate the cellular reorganization of polyadenylated mRNAs associated with the splicing dysfunction in MNs. We demonstrate that SMN deficiency induced the abnormal nuclear accumulation in euchromatin domains of poly(A) RNA granules (PARGs) enriched in the splicing regulator Sam68. However, these granules lacked other RNA-binding proteins, such as TDP43, PABPN1, hnRNPA12B, REF and Y14, which are essential for mRNA processing and nuclear export. These effects were accompanied by changes in the alternative splicing of the Sam68-dependent Bcl-x and Nrnx1 genes, as well as changes in the relative accumulation of the intron-containing Chat, Chodl, Myh9 and Myh14 mRNAs, which are all important for MN functions. PARG-containing MNs were observed at presymptomatic SMA stage, increasing their number during the symptomatic stage. Moreover, the massive accumulations of poly(A) RNA granules in MNs was accompanied by the cytoplasmic depletion of polyadenylated mRNAs for their translation. We suggest that the SMN-dependent abnormal accumulation of polyadenylated mRNAs and Sam68 in PARGs reflects a severe dysfunction of both mRNA processing and translation, which could contribute to SMA pathogenesis.
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Affiliation(s)
- J Oriol Narcís
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain
| | - Olga Tapia
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain
| | - Olga Tarabal
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Lídia Piedrafita
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Jordi Calderó
- Department of Experimental Medicine, School of Medicine, University of Lleida and "Institut de Recerca Biomèdica de Lleida" (IRBLLEIDA), Lleida, Spain
| | - Maria T Berciano
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain.,Department of Molecular Biology and CIBERNED, University of Cantabria-IDIVAL, Santander, Spain
| | - Miguel Lafarga
- Department of Anatomy and Cell Biology and "Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)", University of Cantabria-IDIVAL, Santander, Spain.
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32
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Eblen ST. Extracellular-Regulated Kinases: Signaling From Ras to ERK Substrates to Control Biological Outcomes. Adv Cancer Res 2018; 138:99-142. [PMID: 29551131 DOI: 10.1016/bs.acr.2018.02.004] [Citation(s) in RCA: 125] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The extracellular-regulated kinases ERK1 and ERK2 are evolutionarily conserved, ubiquitous serine-threonine kinases that are involved in regulating cellular signaling in both normal and pathological conditions. Their expression is critical for development and their hyperactivation is a major factor in cancer development and progression. Since their discovery as one of the major signaling mediators activated by mitogens and Ras mutation, we have learned much about their regulation, including their activation, binding partners and substrates. In this review I will discuss some of what has been discovered about the members of the Ras to ERK pathway, including regulation of their activation by growth factors and cell adhesion pathways. Looking downstream of ERK activation I will also highlight some of the many ERK substrates that have been discovered, including those involved in feedback regulation, cell migration and cell cycle progression through the control of transcription, pre-mRNA splicing and protein synthesis.
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Affiliation(s)
- Scott T Eblen
- Medical University of South Carolina, Charleston, SC, United States.
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33
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Goel RK, Paczkowska M, Reimand J, Napper S, Lukong KE. Phosphoproteomics Analysis Identifies Novel Candidate Substrates of the Nonreceptor Tyrosine Kinase, Src- related Kinase Lacking C-terminal Regulatory Tyrosine and N-terminal Myristoylation Sites (SRMS). Mol Cell Proteomics 2018; 17:925-947. [PMID: 29496907 DOI: 10.1074/mcp.ra118.000643] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Indexed: 01/23/2023] Open
Abstract
SRMS (Src-related kinase lacking C-terminal regulatory tyrosine and N-terminal myristoylation sites), also known as PTK 70 (Protein tyrosine kinase 70), is a non-receptor tyrosine kinase that belongs to the BRK family of kinases (BFKs). To date less is known about the cellular role of SRMS primarily because of the unidentified substrates or signaling intermediates regulated by the kinase. In this study, we used phosphotyrosine antibody-based immunoaffinity purification in large-scale label-free quantitative phosphoproteomics to identify novel candidate substrates of SRMS. Our analyses led to the identification of 1258 tyrosine-phosphorylated peptides which mapped to 663 phosphoproteins, exclusively from SRMS-expressing cells. DOK1, a previously characterized SRMS substrate, was also identified in our analyses. Functional enrichment analyses revealed that the candidate SRMS substrates were enriched in various biological processes including protein ubiquitination, mitotic cell cycle, energy metabolism and RNA processing, as well as Wnt and TNF signaling. Analyses of the sequence surrounding the phospho-sites in these proteins revealed novel candidate SRMS consensus substrate motifs. We utilized customized high-throughput peptide arrays to validate a subset of the candidate SRMS substrates identified in our MS-based analyses. Finally, we independently validated Vimentin and Sam68, as bona fide SRMS substrates through in vitro and in vivo assays. Overall, our study identified a number of novel and biologically relevant SRMS candidate substrates, which suggests the involvement of the kinase in a vast array of unexplored cellular functions.
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Affiliation(s)
- Raghuveera Kumar Goel
- From the ‡Department of Biochemistry, College of Medicine, 107 Wiggins Road, University of Saskatchewan, Saskatoon S7N 5E5, Saskatchewan, Canada
| | - Marta Paczkowska
- §Computational Biology Program, Ontario Institute for Cancer Research, 661 University Ave Suite 510, Toronto M5G 0A3, Ontario, Canada
| | - Jüri Reimand
- §Computational Biology Program, Ontario Institute for Cancer Research, 661 University Ave Suite 510, Toronto M5G 0A3, Ontario, Canada.,¶Department of Medical Biophysics, University of Toronto, 101 College Street Suite 15-701, Toronto M5G 1L7, Ontario, Canada
| | - Scott Napper
- From the ‡Department of Biochemistry, College of Medicine, 107 Wiggins Road, University of Saskatchewan, Saskatoon S7N 5E5, Saskatchewan, Canada.,‖Vaccine and Infectious Disease Organization - International Vaccine Centre (VIDO-InterVac), 120 Veterinary Road, University of Saskatchewan, Saskatoon S7N 5E3, Saskatchewan, Canada
| | - Kiven Erique Lukong
- From the ‡Department of Biochemistry, College of Medicine, 107 Wiggins Road, University of Saskatchewan, Saskatoon S7N 5E5, Saskatchewan, Canada;
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34
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Wang S, Yang Q, Wang Z, Feng S, Li H, Ji D, Zhang S. Evolutionary and Expression Analyses Show Co-option of khdrbs Genes for Origin of Vertebrate Brain. Front Genet 2018; 8:225. [PMID: 29354154 PMCID: PMC5758493 DOI: 10.3389/fgene.2017.00225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 12/15/2017] [Indexed: 11/13/2022] Open
Abstract
Genes generated by whole genome duplications (WGD) can be co-opted by changing their regulation process or altering their coding proteins, which has been shown contributable to the emergence of vertebrate morphological novelties such as vertebrate cartilage. Mouse khdrbs genes, differing from its invertebrate orthologs, were mainly expressed in brain, hinting that khdrbs gene family as a member of genetic toolkit may be linked to vertebrate brain development. However, the evolutionary relationship between khdrbs gene family and vertebrate brain development is unclear. First, we analyzed the evolutionary history of khdrbs gene family in metazoans, and then investigated their expression patterns during early development and in adulthood of zebrafish. We found that the duplication of khdrbs gene family by WGD took place in zebrafish, and all zebrafish khdrbs genes were predominantly expressed in the substructures of brain during early development. Given the expression of invertebrate khdrbs gene in germ line, the distinct expression domains of zebrafish khdrbs genes in brain suggested that the duplicated khdrbs genes are co-opted for promoting the evolutionary origin of vertebrate brain.
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Affiliation(s)
- Su Wang
- Laboratory for Evolution and Development, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.,Laboratory for Evolution and Development, Department of Marine Biology, Ocean University of China, Qingdao, China
| | - Qingyun Yang
- Laboratory for Evolution and Development, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.,Laboratory for Evolution and Development, Department of Marine Biology, Ocean University of China, Qingdao, China
| | - Ziyue Wang
- Laboratory for Evolution and Development, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.,Laboratory for Evolution and Development, Department of Marine Biology, Ocean University of China, Qingdao, China
| | - Shuoqi Feng
- Laboratory for Evolution and Development, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.,Laboratory for Evolution and Development, Department of Marine Biology, Ocean University of China, Qingdao, China
| | - Hongyan Li
- Laboratory for Evolution and Development, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.,Laboratory for Evolution and Development, Department of Marine Biology, Ocean University of China, Qingdao, China
| | - Dongrui Ji
- Laboratory for Evolution and Development, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.,Laboratory for Evolution and Development, Department of Marine Biology, Ocean University of China, Qingdao, China
| | - Shicui Zhang
- Laboratory for Evolution and Development, Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.,Laboratory for Evolution and Development, Department of Marine Biology, Ocean University of China, Qingdao, China
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35
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Tichon A, Perry RBT, Stojic L, Ulitsky I. SAM68 is required for regulation of Pumilio by the NORAD long noncoding RNA. Genes Dev 2018; 32:70-78. [PMID: 29386330 PMCID: PMC5828396 DOI: 10.1101/gad.309138.117] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 12/18/2017] [Indexed: 12/31/2022]
Abstract
The number of known long noncoding RNA (lncRNA) functions is rapidly growing, but how those functions are encoded in their sequence and structure remains poorly understood. NORAD (noncoding RNA activated by DNA damage) is a recently characterized, abundant, and highly conserved lncRNA that is required for proper mitotic divisions in human cells. NORAD acts in the cytoplasm and antagonizes repressors from the Pumilio family that bind at least 17 sites spread through 12 repetitive units in NORAD sequence. Here we study conserved sequences in NORAD repeats, identify additional interacting partners, and characterize the interaction between NORAD and the RNA-binding protein SAM68 (KHDRBS1), which is required for NORAD function in antagonizing Pumilio. These interactions provide a paradigm for how repeated elements in a lncRNA facilitate function.
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Affiliation(s)
- Ailone Tichon
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rotem Ben-Tov Perry
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Lovorka Stojic
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge CB2 0RE, United Kingdom
| | - Igor Ulitsky
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
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36
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Hong S. RNA Binding Protein as an Emerging Therapeutic Target for Cancer Prevention and Treatment. J Cancer Prev 2017; 22:203-210. [PMID: 29302577 PMCID: PMC5751837 DOI: 10.15430/jcp.2017.22.4.203] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 11/17/2017] [Accepted: 11/21/2017] [Indexed: 12/13/2022] Open
Abstract
After transcription, RNAs are always associated with RNA binding proteins (RBPs) to perform biological activities. RBPs can interact with target RNAs in sequence- and structure-dependent manner through their unique RNA binding domains. In development and progression of carcinogenesis, RBPs are aberrantly dysregulated in many human cancers with various mechanisms, such as genetic alteration, epigenetic change, noncoding RNA-mediated regulation, and post-translational modifications. Upon deregulation in cancers, RBPs influence every step in the development and progression of cancer, including sustained cell proliferation, evasion of apoptosis, avoiding immune surveillance, inducing angiogenesis, and activating metastasis. To develop therapeutic strategies targeting RBPs, RNA interference-based oligonucleotides or small molecule inhibitors have been screened based on reduced RBP-RNA interaction and changed level of target RNAs. Identification of binding RNAs with high-throughput techniques and integral analysis of multiple datasets will help us develop new therapeutic drugs or prognostic biomarkers for human cancers.
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Affiliation(s)
- Suntaek Hong
- Department of Biochemistry, College of Medicine, Gachon University, Incheon, Korea
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37
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Sharma M, Anirudh CR. Mechanism of mRNA-STAR domain interaction: Molecular dynamics simulations of Mammalian Quaking STAR protein. Sci Rep 2017; 7:12567. [PMID: 28974714 PMCID: PMC5626755 DOI: 10.1038/s41598-017-12930-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 09/20/2017] [Indexed: 01/08/2023] Open
Abstract
STAR proteins are evolutionary conserved mRNA-binding proteins that post-transcriptionally regulate gene expression at all stages of RNA metabolism. These proteins possess conserved STAR domain that recognizes identical RNA regulatory elements as YUAAY. Recently reported crystal structures show that STAR domain is composed of N-terminal QUA1, K-homology domain (KH) and C-terminal QUA2, and mRNA binding is mediated by KH-QUA2 domain. Here, we present simulation studies done to investigate binding of mRNA to STAR protein, mammalian Quaking protein (QKI). We carried out conventional MD simulations of STAR domain in presence and absence of mRNA, and studied the impact of mRNA on the stability, dynamics and underlying allosteric mechanism of STAR domain. Our unbiased simulations results show that presence of mRNA stabilizes the overall STAR domain by reducing the structural deviations, correlating the ‘within-domain’ motions, and maintaining the native contacts information. Absence of mRNA not only influenced the essential modes of motion of STAR domain, but also affected the connectivity of networks within STAR domain. We further explored the dissociation of mRNA from STAR domain using umbrella sampling simulations, and the results suggest that mRNA binding to STAR domain occurs in multi-step: first conformational selection of mRNA backbone conformations, followed by induced fit mechanism as nucleobases interact with STAR domain.
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Affiliation(s)
- Monika Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Sector 81, Knowledge City, SAS Nagar, Punjab, India.
| | - C R Anirudh
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Sector 81, Knowledge City, SAS Nagar, Punjab, India
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38
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Wen H, Li P, Ma H, Zheng J, Yu Y, Lv G. High expression of Sam68 in sacral chordomas is associated with worse clinical outcomes. Onco Targets Ther 2017; 10:4691-4700. [PMID: 29026317 PMCID: PMC5626414 DOI: 10.2147/ott.s147446] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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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39
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Danilenko M, Dalgliesh C, Pagliarini V, Naro C, Ehrmann I, Feracci M, Kheirollahi-Chadegani M, Tyson-Capper A, Clowry GJ, Fort P, Dominguez C, Sette C, Elliott DJ. Binding site density enables paralog-specific activity of SLM2 and Sam68 proteins in Neurexin2 AS4 splicing control. Nucleic Acids Res 2017; 45:4120-4130. [PMID: 27994030 PMCID: PMC5397175 DOI: 10.1093/nar/gkw1277] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 12/08/2016] [Indexed: 01/09/2023] Open
Abstract
SLM2 and Sam68 are splicing regulator paralogs that usually overlap in function, yet only SLM2 and not Sam68 controls the Neurexin2 AS4 exon important for brain function. Herein we find that SLM2 and Sam68 similarly bind to Neurexin2 pre-mRNA, both within the mouse cortex and in vitro. Protein domain-swap experiments identify a region including the STAR domain that differentiates SLM2 and Sam68 activity in splicing target selection, and confirm that this is not established via the variant amino acids involved in RNA contact. However, far fewer SLM2 and Sam68 RNA binding sites flank the Neurexin2 AS4 exon, compared with those flanking the Neurexin1 and Neurexin3 AS4 exons under joint control by both Sam68 and SLM2. Doubling binding site numbers switched paralog sensitivity, by placing the Neurexin2 AS4 exon under joint splicing control by both Sam68 and SLM2. Our data support a model where the density of shared RNA binding sites around a target exon, rather than different paralog-specific protein-RNA binding sites, controls functional target specificity between SLM2 and Sam68 on the Neurexin2 AS4 exon. Similar models might explain differential control by other splicing regulators within families of paralogs with indistinguishable RNA binding sites.
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Affiliation(s)
- Marina Danilenko
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
| | - Caroline Dalgliesh
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
| | - Vittoria Pagliarini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, 00143 Rome, Italy
| | - Chiara Naro
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, 00143 Rome, Italy
| | - Ingrid Ehrmann
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
| | - Mikael Feracci
- Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7RH, UK
| | | | - Alison Tyson-Capper
- Institute for Cellular Medicine, Newcastle University, Framlington Place, Newcastle NE2 4HH, UK
| | - Gavin J Clowry
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle, UK
| | - Philippe Fort
- Université Montpellier, UMR 5237, Centre de Recherche de Biologie cellulaire de Montpellier, CNRS, 34293 Montpellier, France
| | - Cyril Dominguez
- Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7RH, UK
| | - Claudio Sette
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, 00143 Rome, Italy
| | - David J Elliott
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
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40
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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] [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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41
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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: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [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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42
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Sun X, Fu K, Hodgson A, Wier EM, Wen MG, Kamenyeva O, Xia X, Koo LY, Wan F. Sam68 Is Required for DNA Damage Responses via Regulating Poly(ADP-ribosyl)ation. PLoS Biol 2016; 14:e1002543. [PMID: 27635653 PMCID: PMC5026359 DOI: 10.1371/journal.pbio.1002543] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/04/2016] [Indexed: 01/08/2023] Open
Abstract
The rapid and robust synthesis of polymers of adenosine diphosphate (ADP)-ribose (PAR) chains, primarily catalyzed by poly(ADP-ribose) polymerase 1 (PARP1), is crucial for cellular responses to DNA damage. However, the precise mechanisms through which PARP1 is activated and PAR is robustly synthesized are not fully understood. Here, we identified Src-associated substrate during mitosis of 68 kDa (Sam68) as a novel signaling molecule in DNA damage responses (DDRs). In the absence of Sam68, DNA damage-triggered PAR production and PAR-dependent DNA repair signaling were dramatically diminished. With serial cellular and biochemical assays, we demonstrated that Sam68 is recruited to and significantly overlaps with PARP1 at DNA lesions and that the interaction between Sam68 and PARP1 is crucial for DNA damage-initiated and PARP1-conferred PAR production. Utilizing cell lines and knockout mice, we illustrated that Sam68-deleted cells and animals are hypersensitive to genotoxicity caused by DNA-damaging agents. Together, our findings suggest that Sam68 plays a crucial role in DDR via regulating DNA damage-initiated PAR production. The RNA-binding protein Sam68 has unexpected function in the early signaling of DNA damage, and is critical for the activation and regulation of poly(ADP-ribose) polymerase 1 in response to DNA damage. Maintaining genome integrity is crucial for all organisms, and failure to do so can lead to fatal diseases such as cancer. Exposure to challenging environments can induce DNA strand breaks or other lesions; thus, rapid and appropriate DNA damage responses (DDRs) need to be in place to detect and repair the damage. Cellular networks use a variety of signaling molecules and post-translational modifications that are crucial for the signaling of DNA breaks to repair machineries. Poly(adenosine diphosphate [ADP]-ribosyl)ation (PARylation) and activation of the enzyme poly(ADP-ribose) polymerase 1 (PARP1) is a post-translational modification that occurs within seconds upon DNA damage detection and triggers downstream DDR signaling; however, it remains obscure whether other molecules, beyond DNA strand breaks, stimulate or control PARP1 activity. We report here that a novel DDR signaling molecule, Src-associated substrate during mitosis of 68 kDa (Sam68), has a crucial function in governing the DNA damage-initiated PARP1 activation and polymers of ADP-ribose (PAR) production. We show that Sam68 is recruited to and significantly overlaps with PARP1 at DNA lesions and that the Sam68-PARP1 interaction is critical for DNA damage-initiated PARP1 activation and PAR production both in vitro and in vivo. Sam68-deleted cells and animals have a diminished PAR-dependent DNA repair signaling and are hypersensitive to genotoxicity caused by DNA-damaging agents. Hence, our data reveal an unexpected function for Sam68 in DNA damage-initiated early signaling and provide a novel mechanism on the activation and regulation of PARP1 in DDR.
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Affiliation(s)
- Xin Sun
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Kai Fu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Andrea Hodgson
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Eric M. Wier
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Matthew G. Wen
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Olena Kamenyeva
- Biological Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Xue Xia
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Lily Y. Koo
- Biological Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Fengyi Wan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Oncology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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Abstract
Alternative precursor-mRNA splicing is a key mechanism for regulating gene expression in mammals and is controlled by specialized RNA-binding proteins. The misregulation of splicing is implicated in multiple neurological disorders. We describe recent mouse genetic studies of alternative splicing that reveal its critical role in both neuronal development and the function of mature neurons. We discuss the challenges in understanding the extensive genetic programmes controlled by proteins that regulate splicing, both during development and in the adult brain.
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Affiliation(s)
- Celine K Vuong
- Molecular Biology Interdepartmental Graduate Program, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Douglas L Black
- Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Sika Zheng
- Division of Biomedical Sciences, University of California at Riverside, Riverside, California 92521, USA
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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: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [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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Sam68 Mediates the Activation of Insulin and Leptin Signalling in Breast Cancer Cells. PLoS One 2016; 11:e0158218. [PMID: 27415018 PMCID: PMC4944952 DOI: 10.1371/journal.pone.0158218] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 06/13/2016] [Indexed: 12/23/2022] Open
Abstract
Obesity is a well-known risk factor for breast cancer development in postmenopausal women. High insulin and leptin levels seem to have a role modulating the growth of these tumours. Sam68 is an RNA-binding protein with signalling functions that has been found to be overexpressed in breast cancer. Moreover, Sam68 may be recruited to insulin and leptin signalling pathways, mediating its effects on survival, growth and proliferation in different cellular types. We aimed to study the expression of Sam68 and its phosphorylation level upon insulin and leptin stimulation, and the role of Sam68 in the proliferative effect and signalling pathways that are activated by insulin or leptin in human breast adenocarcinoma cells. In the human breast adenocarcinoma cell lines MCF7, MDA-MB-231 and BT-474, Sam68 protein quantity and gene expression were increased upon leptin or insulin stimulation, as it was checked by qPCR and immunoblot. Moreover, both insulin and leptin stimulation promoted an increase in Sam68 tyrosine phosphorylation and negatively regulated its RNA binding capacity. siRNA was used to downregulate Sam68 expression, which resulted in lower proliferative effects of both insulin and leptin, as well as a lower activation of MAPK and PI3K pathways promoted by both hormones. These effects may be partly explained by the decrease in IRS-1 expression by down-regulation of Sam68. These results suggest the participation of Sam68 in both leptin and insulin receptor signaling in human breast cancer cells, mediating the trophic effects of these hormones in proliferation and cellular growth.
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Sam68 is a regulator of Toll-like receptor signaling. Cell Mol Immunol 2016; 14:107-117. [PMID: 27374795 PMCID: PMC5214940 DOI: 10.1038/cmi.2016.32] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 05/14/2016] [Accepted: 05/15/2016] [Indexed: 12/17/2022] Open
Abstract
Recognition of pathogens by Toll-like receptors (TLR) activate multiple signaling cascades and expression of genes tailored to mount a primary immune response, inflammation, cell survival and apoptosis. Although TLR-induced activation of pathways, such as nuclear factor kappaB (NF-κB) and mitogen-activated protein kinases (MAPK), has been well studied, molecular entities controlling quantitative regulation of these pathways during an immune response remain poorly defined. We identified Sam68 as a novel regulator of TLR-induced NF-κB and MAPK activation. We found that TLR2 and TLR3 are totally dependent, whereas TLR4 is only partially dependent on Sam68 to induce the activation of NF-κB c-Rel. Absence of Sam68 greatly decreased TLR2- and TLR3-induced NF-κB p65 activation, whereas TLR4-induced p65 activation in a Sam68-independent manner. In contrast, Sam68 appeared to be a negative regulator of MAPK pathways because absence of Sam68 enhanced TLR2-induced activation of extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK). Interestingly, TLR2- and TLR3-induced gene expression showed a differential requirement of Sam68. Absence of Sam68 impaired TLR2-induced gene expression, suggesting that Sam68 has a critical role in myeloid differentiation primary response gene 88-dependent TLR2 signaling. TLR3-induced gene expression that utilize Toll/Interleukin-1 receptor-domain-containing adapter-inducing beta interferon pathway, depend only partially on Sam68. Our findings suggest that Sam68 may function as an immune rheostat that balances the activation of NF-κB p65 and c-Rel, as well as MAPK, revealing a potential novel target to manipulate TLR signaling.
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47
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Wang Q, Li Y, Cheng J, Chen L, Xu H, Li Q, Pang T. Sam68 affects cell proliferation and apoptosis of human adult T-acute lymphoblastic leukemia cells via AKT/mTOR signal pathway. Leuk Res 2016; 46:1-9. [DOI: 10.1016/j.leukres.2016.04.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 04/07/2016] [Accepted: 04/11/2016] [Indexed: 01/02/2023]
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Li N, Richard S. Sam68 functions as a transcriptional coactivator of the p53 tumor suppressor. Nucleic Acids Res 2016; 44:8726-8741. [PMID: 27365047 PMCID: PMC5062974 DOI: 10.1093/nar/gkw582] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/18/2016] [Indexed: 02/07/2023] Open
Abstract
Sam68 is a known sequence-specific RNA binding protein that regulates alternative splicing events during the cell cycle and apoptosis. Sam68 has also been shown to influence transcription, but the molecular mechanism remains undefined. Herein we identify Sam68 as a transcriptional coactivator of the p53 tumor suppressor in response to DNA damage. Using CRISPR/Cas9 generated isogenic HCT116 Sam68−/− cell lines wild type or deficient for p53, we show that Sam68 is required for the efficient transactivation of p53 target genes. Consistently, Sam68 depletion caused defects in DNA damage-induced cell cycle arrest and apoptosis mediated by p53. Mechanistically, we demonstrate that Sam68 physically interacted with p53 in an RNA-dependent manner, and that this interaction was essential for the coactivator function of Sam68. Furthermore, we show that both Sam68 and p53 were recruited to promoters of p53-responsive genes, suggesting interdependence. Finally, Sam68 acted in concert with the p53 long noncoding RNA (lncRNA) target PR-lncRNA-1 for p53 recruitment, implicating a positive-feedback mechanism in which lncRNAs induced by the Sam68/p53 complex can enhance p53 transcriptional activity. These findings define a hitherto novel mechanism of action for Sam68 in governing p53 transcriptional activation, and represent the first report of Sam68 in the regulation of tumor suppressor activities.
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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
| | - 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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Feracci M, Foot JN, Grellscheid SN, Danilenko M, Stehle R, Gonchar O, Kang HS, Dalgliesh C, Meyer NH, Liu Y, Lahat A, Sattler M, Eperon IC, Elliott DJ, Dominguez C. Structural basis of RNA recognition and dimerization by the STAR proteins T-STAR and Sam68. Nat Commun 2016; 7:10355. [PMID: 26758068 PMCID: PMC4735526 DOI: 10.1038/ncomms10355] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 12/01/2015] [Indexed: 11/13/2022] Open
Abstract
Sam68 and T-STAR are members of the STAR family of proteins that directly link signal transduction with post-transcriptional gene regulation. Sam68 controls the alternative splicing of many oncogenic proteins. T-STAR is a tissue-specific paralogue that regulates the alternative splicing of neuronal pre-mRNAs. STAR proteins differ from most splicing factors, in that they contain a single RNA-binding domain. Their specificity of RNA recognition is thought to arise from their property to homodimerize, but how dimerization influences their function remains unknown. Here, we establish at atomic resolution how T-STAR and Sam68 bind to RNA, revealing an unexpected mode of dimerization different from other members of the STAR family. We further demonstrate that this unique dimerization interface is crucial for their biological activity in splicing regulation, and suggest that the increased RNA affinity through dimer formation is a crucial parameter enabling these proteins to select their functional targets within the transcriptome. Sam68 and T-STAR are members of the STAR family of proteins, which regulate various aspects of RNA metabolism. Here, the authors reveal structural features required for alternative splicing regulation by these proteins.
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Affiliation(s)
- Mikael Feracci
- Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Jaelle N Foot
- Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Sushma N Grellscheid
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
| | - Marina Danilenko
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
| | - Ralf Stehle
- Center for Integrated Protein Science Munich at Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, DE-85747 Garching, Germany
| | - Oksana Gonchar
- Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Hyun-Seo Kang
- Center for Integrated Protein Science Munich at Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, DE-85747 Garching, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, DE-85764 Oberschleißheim, Germany
| | - Caroline Dalgliesh
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
| | - N Helge Meyer
- Center for Integrated Protein Science Munich at Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, DE-85747 Garching, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, DE-85764 Oberschleißheim, Germany
| | - Yilei Liu
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
| | - Albert Lahat
- School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, UK
| | - Michael Sattler
- Center for Integrated Protein Science Munich at Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstr. 4, DE-85747 Garching, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, DE-85764 Oberschleißheim, Germany
| | - Ian C Eperon
- Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, UK
| | - David J Elliott
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle NE1 3BZ, UK
| | - Cyril Dominguez
- Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, UK
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Rai DK, Lawrence P, Kloc A, Schafer E, Rieder E. Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections. Virol J 2015; 12:224. [PMID: 26695943 PMCID: PMC4689063 DOI: 10.1186/s12985-015-0452-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/10/2015] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The nuclear protein Src-associated protein of 68 kDa in mitosis (Sam68) is known to bind RNA and be involved in cellular processes triggered in response to environmental stresses, including virus infection. Interestingly, Sam68 is a multi-functional protein implicated in the life cycle of retroviruses and picornaviruses and is also considered a marker of virus-induced stress granules (SGs). Recently, we demonstrated the partial redistribution of Sam68 to the cytoplasm in FMDV infected cells, its interaction with viral protease 3C(pro), and found a significant reduction in viral titers as consequence of Sam68-specific siRNA knockdowns. Despite of that, details of how it benefits FMDV remains to be elucidated. METHODS Sam68 cytoplasmic localization was examined by immunofluorescent microscopy, counterstaining with antibodies against Sam68, a viral capsid protein and markers of SGs. The relevance of RAAA motifs in the IRES was investigated using electromobility shift assays with Sam68 protein and parental and mutant FMDV RNAs. In addition, full genome WT and mutant or G-luc replicon RNAs were tested following transfection in mammalian cells. The impact of Sam68 depletion to virus protein and RNA synthesis was investigated in a cell-free system. Lastly, through co-immunoprecipitation, structural modeling, and subcellular fractionation, viral protein interactions with Sam68 were explored. RESULTS FMDV-induced cytoplasmic redistribution of Sam68 resulted in it temporarily co-localizing with SG marker: TIA-1. Mutations that disrupted FMDV IRES RAAA motifs, with putative affinity to Sam68 in domain 3 and 4 cause a reduction on the formation of ribonucleoprotein complexes with this protein and resulted in non-viable progeny viruses and replication-impaired replicons. Furthermore, depletion of Sam68 in cell-free extracts greatly diminished FMDV RNA replication, which was restored by addition of recombinant Sam68. The results here demonstrated that Sam68 specifically co-precipitates with both FMDV 3D(pol) and 3C(pro) consistent with early observations of FMDV 3C(pro)-induced cleavage of Sam68. CONCLUSION We have found that Sam68 is a specific binding partner for FMDV non-structural proteins 3C(pro) and 3D(pol) and showed that mutations at RAAA motifs in IRES domains 3 and 4 cause a decrease in Sam68 affinity to these RNA elements and rendered the mutant RNA non-viable. Interestingly, in FMDV infected cells re-localized Sam68 was transiently detected along with SG markers in the cytoplasm. These results support the importance of Sam68 as a host factor co-opted by FMDV during infection and demonstrate that Sam68 interact with both, FMDV RNA motifs in the IRES and viral non-structural proteins 3C(pro) and 3D(pol).
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Affiliation(s)
- Devendra K Rai
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Paul Lawrence
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Anna Kloc
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Elizabeth Schafer
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Elizabeth Rieder
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
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