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Gavrilova AA, Fefilova AS, Vishnyakov IE, Kuznetsova IM, Turoverov KK, Uversky VN, Fonin AV. On the Roles of the Nuclear Non-Coding RNA-Dependent Membrane-Less Organelles in the Cellular Stress Response. Int J Mol Sci 2023; 24:ijms24098108. [PMID: 37175815 PMCID: PMC10179167 DOI: 10.3390/ijms24098108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
At the beginning of the 21st century, it became obvious that radical changes had taken place in the concept of living matter and, in particular, in the concept of the organization of intracellular space. The accumulated data testify to the essential importance of phase transitions of biopolymers (first of all, intrinsically disordered proteins and RNA) in the spatiotemporal organization of the intracellular space. Of particular interest is the stress-induced reorganization of the intracellular space. Examples of organelles formed in response to stress are nuclear A-bodies and nuclear stress bodies. The formation of these organelles is based on liquid-liquid phase separation (LLPS) of intrinsically disordered proteins (IDPs) and non-coding RNA. Despite their overlapping composition and similar mechanism of formation, these organelles have different functional activities and physical properties. In this review, we will focus our attention on these membrane-less organelles (MLOs) and describe their functions, structure, and mechanism of formation.
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Affiliation(s)
- Anastasia A Gavrilova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg, Russia
| | - Anna S Fefilova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg, Russia
| | - Innokentii E Vishnyakov
- Group of Molecular Cytology of Prokaryotes and Bacterial Invasion, Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg, Russia
| | - Irina M Kuznetsova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg, Russia
| | - Konstantin K Turoverov
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg, Russia
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Alexander V Fonin
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg, Russia
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Taze C, Drakouli S, Samiotaki M, Panayotou G, Simos G, Georgatsou E, Mylonis I. Short-term hypoxia triggers ROS and SAFB mediated nuclear matrix and mRNA splicing remodeling. Redox Biol 2022; 58:102545. [PMID: 36427398 PMCID: PMC9692040 DOI: 10.1016/j.redox.2022.102545] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 11/16/2022] [Indexed: 11/18/2022] Open
Abstract
The cellular response to hypoxia, in addition to HIF-dependent transcriptional reprogramming, also involves less characterized transcription-independent processes, such as alternative splicing of the VEGFA transcript leading to the production of the proangiogenic VEGF form. We now show that this event depends on reorganization of the splicing machinery, triggered after short-term hypoxia by ROS production and intranuclear redistribution of the nucleoskeletal proteins SAFB1/2. Exposure to low oxygen causes fast dissociation of SAFB1/2 from the nuclear matrix, which is reversible, inhibited by antioxidant treatment, and also observed under normoxia when the mitochondrial electron transport chain is blocked. This is accompanied by altered interactions between SAFB1/2 and the splicing machinery, translocation of kinase SRPK1 to the cytoplasm, and dephosphorylation of RS-splicing factors. Depletion of SAFB1/2 under normoxia phenocopies the hypoxic and ROS-mediated switch in VEGF mRNA splicing. These data suggest that ROS-dependent remodeling of the nuclear architecture can promote production of splicing variants that facilitate adaptation to hypoxia.
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Affiliation(s)
- Chrysa Taze
- Laboratory of Biochemistry, Faculty of Medicine, University of Thessaly, Biopolis, Larissa, 41500, Greece
| | - Sotiria Drakouli
- Laboratory of Biochemistry, Faculty of Medicine, University of Thessaly, Biopolis, Larissa, 41500, Greece
| | - Martina Samiotaki
- Institute for Bioinnovation, BSRC “Alexander Fleming”, Vari, 16672, Greece
| | - George Panayotou
- Institute for Bioinnovation, BSRC “Alexander Fleming”, Vari, 16672, Greece
| | - George Simos
- Laboratory of Biochemistry, Faculty of Medicine, University of Thessaly, Biopolis, Larissa, 41500, Greece,Gerald Bronfman Department of Oncology, Faculty of Medicine, McGill University, Montreal, H4A 3T2, Canada
| | - Eleni Georgatsou
- Laboratory of Biochemistry, Faculty of Medicine, University of Thessaly, Biopolis, Larissa, 41500, Greece
| | - Ilias Mylonis
- Laboratory of Biochemistry, Faculty of Medicine, University of Thessaly, Biopolis, Larissa, 41500, Greece,Corresponding author.
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Bell RAV, Al-Khalaf MH, Brunette S, Alsowaida D, Chu A, Bandukwala H, Dechant G, Apostolova G, Dilworth FJ, Megeney LA. Chromatin Reorganization during Myoblast Differentiation Involves the Caspase-Dependent Removal of SATB2. Cells 2022; 11:cells11060966. [PMID: 35326417 PMCID: PMC8946544 DOI: 10.3390/cells11060966] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 02/27/2022] [Accepted: 03/09/2022] [Indexed: 11/17/2022] Open
Abstract
The induction of lineage-specific gene programs are strongly influenced by alterations in local chromatin architecture. However, key players that impact this genome reorganization remain largely unknown. Here, we report that the removal of the special AT-rich binding protein 2 (SATB2), a nuclear protein known to bind matrix attachment regions, is a key event in initiating myogenic differentiation. The deletion of myoblast SATB2 in vitro initiates chromatin remodeling and accelerates differentiation, which is dependent on the caspase 7-mediated cleavage of SATB2. A genome-wide analysis indicates that SATB2 binding within chromatin loops and near anchor points influences both loop and sub-TAD domain formation. Consequently, the chromatin changes that occur with the removal of SATB2 lead to the derepression of differentiation-inducing factors while also limiting the expression of genes that inhibit this cell fate change. Taken together, this study demonstrates that the temporal control of the SATB2 protein is critical in shaping the chromatin environment and coordinating the myogenic differentiation program.
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Affiliation(s)
- Ryan A. V. Bell
- Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada; (R.A.V.B.); (M.H.A.-K.); (S.B.); (D.A.); (A.C.); (H.B.); (F.J.D.)
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Mohammad H. Al-Khalaf
- Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada; (R.A.V.B.); (M.H.A.-K.); (S.B.); (D.A.); (A.C.); (H.B.); (F.J.D.)
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- University of Ottawa Heart Institute, Ottawa, ON K1Y 4W7, Canada
| | - Steve Brunette
- Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada; (R.A.V.B.); (M.H.A.-K.); (S.B.); (D.A.); (A.C.); (H.B.); (F.J.D.)
| | - Dalal Alsowaida
- Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada; (R.A.V.B.); (M.H.A.-K.); (S.B.); (D.A.); (A.C.); (H.B.); (F.J.D.)
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Alphonse Chu
- Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada; (R.A.V.B.); (M.H.A.-K.); (S.B.); (D.A.); (A.C.); (H.B.); (F.J.D.)
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Hina Bandukwala
- Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada; (R.A.V.B.); (M.H.A.-K.); (S.B.); (D.A.); (A.C.); (H.B.); (F.J.D.)
| | - Georg Dechant
- Institute of Neuroscience, Medical University of Innsbruck, A-6020 Innsbruck, Austria; (G.D.); (G.A.)
| | - Galina Apostolova
- Institute of Neuroscience, Medical University of Innsbruck, A-6020 Innsbruck, Austria; (G.D.); (G.A.)
| | - F. Jeffrey Dilworth
- Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada; (R.A.V.B.); (M.H.A.-K.); (S.B.); (D.A.); (A.C.); (H.B.); (F.J.D.)
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Lynn A. Megeney
- Regenerative Medicine Program, Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada; (R.A.V.B.); (M.H.A.-K.); (S.B.); (D.A.); (A.C.); (H.B.); (F.J.D.)
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Correspondence:
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Buckner N, Kemp KC, Scott HL, Shi G, Rivers C, Gialeli A, Wong LF, Cordero-LLana O, Allen N, Wilkins A, Uney JB. Abnormal scaffold attachment factor 1 expression and localization in spinocerebellar ataxias and Huntington's chorea. Brain Pathol 2020; 30:1041-1055. [PMID: 32580238 PMCID: PMC8018166 DOI: 10.1111/bpa.12872] [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] [Indexed: 12/21/2022] Open
Abstract
SAFB1 is a DNA and RNA binding protein that is highly expressed in the cerebellum and hippocampus and is involved in the processing of coding and non-coding RNAs, splicing and dendritic function. We analyzed SAFB1 expression in the post-mortem brain tissue of spinocerebellar ataxia (SCA), Huntington's disease (HD), Multiple sclerosis (MS), Parkinson's disease patients and controls. In SCA cases, the expression of SAFB1 in the nucleus was increased and there was abnormal and extensive expression in the cytoplasm where it co-localized with the markers of Purkinje cell injury. Significantly, no SAFB1 expression was found in the cerebellar neurons of the dentate nucleus in control or MS patients; however, in SCA patients, SAFB1 expression was increased significantly in both the nucleus and cytoplasm of dentate neurons. In HD, we found that SAFB1 expression was increased in the nucleus and cytoplasm of striatal neurons; however, there was no SAFB1 staining in the striatal neurons of controls. In PD substantia nigra, we did not see any changes in neuronal SAFB1 expression. iCLIP analysis found that SAFB1 crosslink sites within ATXN1 RNA were adjacent to the start and within the glutamine repeat sequence. Further investigation found increased binding of SAFB1 to pathogenic ATXN1-85Q mRNA. These novel data strongly suggest SAFB1 contributes to the etiology of SCA and Huntington's chorea and that it may be a pathological marker of polyglutamine repeat expansion diseases.
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Affiliation(s)
- Nicola Buckner
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Kevin C Kemp
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Helen L Scott
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Gongyu Shi
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Caroline Rivers
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Andriana Gialeli
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Liang-Fong Wong
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Oscar Cordero-LLana
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | | | - Alastair Wilkins
- Institute of Clinical Neurosciences, Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
| | - James B Uney
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, UK
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Scaffold attachment factor B: distribution and interaction with ERα in the rat brain. Histochem Cell Biol 2020; 153:323-338. [PMID: 32086573 DOI: 10.1007/s00418-020-01853-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2020] [Indexed: 10/24/2022]
Abstract
Scaffold attachment factor (SAFB) 1 and its homologue SAFB2 are multifunctional proteins that are involved in various cellular mechanisms, including chromatin organization and transcriptional regulation, and are also corepressors of estrogen receptor alpha (ERα). Both SAFBs are expressed at high levels in the brain. However, the distributions of SAFB1 and SAFB2 have yet to be characterized in detail and it is unclear whether both proteins interact with ERα in the brain. In this study, we investigated the expression and distribution of both SAFBs and their interaction with ERα in adult male rat brain. Immunohistochemical staining showed that SAFB1 and SAFB2 have a similar distribution pattern and are widely expressed throughout the brain. Double-fluorescence immunohistochemical and immunocytochemical analyses in primary cultures showed that the two SAFB proteins are localized in nuclei of neurons, astrocytes, and oligodendrocytes. Of note, SAFB2 was also found in cytoplasmic regions in these cell lineages. Both SAFB proteins were also expressed in ERα-positive cells in the medial preoptic area (MPOA) and arcuate and ventromedial hypothalamic nuclei. Co-immunoprecipitation experiments revealed that both SAFB proteins from the MPOA reciprocally interact with endogenous ERα. These results indicate that, in addition to a role in basal cellular function in the brain, the SAFB proteins may serve as ERα corepressors in hormone-sensitive regions.
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Huo X, Ji L, Zhang Y, Lv P, Cao X, Wang Q, Yan Z, Dong S, Du D, Zhang F, Wei G, Liu Y, Wen B. The Nuclear Matrix Protein SAFB Cooperates with Major Satellite RNAs to Stabilize Heterochromatin Architecture Partially through Phase Separation. Mol Cell 2019; 77:368-383.e7. [PMID: 31677973 DOI: 10.1016/j.molcel.2019.10.001] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 07/24/2019] [Accepted: 09/30/2019] [Indexed: 12/16/2022]
Abstract
Interphase chromatin is hierarchically organized into higher-order architectures that are essential for gene functions, yet the biomolecules that regulate these 3D architectures remain poorly understood. Here, we show that scaffold attachment factor B (SAFB), a nuclear matrix (NM)-associated protein with RNA-binding functions, modulates chromatin condensation and stabilizes heterochromatin foci in mouse cells. SAFB interacts via its R/G-rich region with heterochromatin-associated repeat transcripts such as major satellite RNAs, which promote the phase separation driven by SAFB. Depletion of SAFB leads to changes in 3D genome organization, including an increase in interchromosomal interactions adjacent to pericentromeric heterochromatin and a decrease in genomic compartmentalization, which could result from the decondensation of pericentromeric heterochromatin. Collectively, we reveal the integrated roles of NM-associated proteins and repeat RNAs in the 3D organization of heterochromatin, which may shed light on the molecular mechanisms of nuclear architecture organization.
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Affiliation(s)
- Xiangru Huo
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Luzhang Ji
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Yuwen Zhang
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Pin Lv
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Xuan Cao
- CAS Key Laboratory of Computational Biology, Collaborative Innovation Center for Genetics and Developmental Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Qianfeng Wang
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Zixiang Yan
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Shuangshuang Dong
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China; State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200438, China
| | - Duo Du
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Feng Zhang
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai 200011, China; State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200438, China
| | - Gang Wei
- CAS Key Laboratory of Computational Biology, Collaborative Innovation Center for Genetics and Developmental Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yun Liu
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Bo Wen
- Key Laboratory of Metabolism and Molecular Medicine of Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200438, China.
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Proteomics-Based Identification of the Molecular Signatures of Liver Tissues from Aged Rats following Eight Weeks of Medium-Intensity Exercise. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:3269405. [PMID: 28116034 PMCID: PMC5223045 DOI: 10.1155/2016/3269405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Revised: 09/05/2016] [Accepted: 11/28/2016] [Indexed: 02/07/2023]
Abstract
Physical activity has emerged as a powerful intervention that promotes healthy aging by maintaining the functional capacity of critical organ systems. Here, by combining functional and proteomics analyses, we examined how hepatic phenotypes might respond to exercise treatment in aged rats. 16 male aged (20 months old) SD rats were divided into exercise and parallel control groups at random; the exercise group had 8 weeks of treadmill training with medium intensity. Whole protein samples of the liver were extracted from both groups and separated by two-dimensional gel electrophoresis. Alternatively objective protein spots with >2-fold difference in expression were selected for enzymological extraction and MS/MS identification. Results show increased activity of the manganese superoxide dismutase and elevated glutathione levels in the livers of exercise-treated animals, but malondialdehyde contents obviously decreased in the liver of the exercise group. Proteomics-based identification of differentially expressed proteins provided an integrated view of the metabolic adaptations occurring in the liver proteome during exercise, which significantly altered the expression of several proteins involved in key liver metabolic pathways including mitochondrial sulfur, glycolysis, methionine, and protein metabolism. These findings indicate that exercise may be beneficial to aged rats through modulation of hepatic protein expression profiles.
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The increasing diversity of functions attributed to the SAFB family of RNA-/DNA-binding proteins. Biochem J 2016; 473:4271-4288. [DOI: 10.1042/bcj20160649] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/28/2016] [Accepted: 09/02/2016] [Indexed: 12/15/2022]
Abstract
RNA-binding proteins play a central role in cellular metabolism by orchestrating the complex interactions of coding, structural and regulatory RNA species. The SAFB (scaffold attachment factor B) proteins (SAFB1, SAFB2 and SAFB-like transcriptional modulator, SLTM), which are highly conserved evolutionarily, were first identified on the basis of their ability to bind scaffold attachment region DNA elements, but attention has subsequently shifted to their RNA-binding and protein–protein interactions. Initial studies identified the involvement of these proteins in the cellular stress response and other aspects of gene regulation. More recently, the multifunctional capabilities of SAFB proteins have shown that they play crucial roles in DNA repair, processing of mRNA and regulatory RNA, as well as in interaction with chromatin-modifying complexes. With the advent of new techniques for identifying RNA-binding sites, enumeration of individual RNA targets has now begun. This review aims to summarise what is currently known about the functions of SAFB proteins.
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Rivers C, Idris J, Scott H, Rogers M, Lee YB, Gaunt J, Phylactou L, Curk T, Campbell C, Ule J, Norman M, Uney JB. iCLIP identifies novel roles for SAFB1 in regulating RNA processing and neuronal function. BMC Biol 2015; 13:111. [PMID: 26694817 PMCID: PMC4689037 DOI: 10.1186/s12915-015-0220-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 12/10/2015] [Indexed: 01/07/2023] Open
Abstract
Background SAFB1 is a RNA binding protein implicated in the regulation of multiple cellular processes such as the regulation of transcription, stress response, DNA repair and RNA processing. To gain further insight into SAFB1 function we used iCLIP and mapped its interaction with RNA on a genome wide level. Results iCLIP analysis found SAFB1 binding was enriched, specifically in exons, ncRNAs, 3’ and 5’ untranslated regions. SAFB1 was found to recognise a purine-rich GAAGA motif with the highest frequency and it is therefore likely to bind core AGA, GAA, or AAG motifs. Confirmatory RT-PCR experiments showed that the expression of coding and non-coding genes with SAFB1 cross-link sites was altered by SAFB1 knockdown. For example, we found that the isoform-specific expression of neural cell adhesion molecule (NCAM1) and ASTN2 was influenced by SAFB1 and that the processing of miR-19a from the miR-17-92 cluster was regulated by SAFB1. These data suggest SAFB1 may influence alternative splicing and, using an NCAM1 minigene, we showed that SAFB1 knockdown altered the expression of two of the three NCAM1 alternative spliced isoforms. However, when the AGA, GAA, and AAG motifs were mutated, SAFB1 knockdown no longer mediated a decrease in the NCAM1 9–10 alternative spliced form. To further investigate the association of SAFB1 with splicing we used exon array analysis and found SAFB1 knockdown mediated the statistically significant up- and downregulation of alternative exons. Further analysis using RNAmotifs to investigate the frequency of association between the motif pairs (AGA followed by AGA, GAA or AAG) and alternative spliced exons found there was a highly significant correlation with downregulated exons. Together, our data suggest SAFB1 will play an important physiological role in the central nervous system regulating synaptic function. We found that SAFB1 regulates dendritic spine density in hippocampal neurons and hence provide empirical evidence supporting this conclusion. Conclusions iCLIP showed that SAFB1 has previously uncharacterised specific RNA binding properties that help coordinate the isoform-specific expression of coding and non-coding genes. These genes regulate splicing, axonal and synaptic function, and are associated with neuropsychiatric disease, suggesting that SAFB1 is an important regulator of key neuronal processes. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0220-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Caroline Rivers
- Regenerative Medicine Laboratories, School of Clinical Sciences, Cellular & Molecular Medicine, Medical Sciences Building, University Walk, University of Bristol, Bristol, BS8 1TD, UK.
| | - Jalilah Idris
- Regenerative Medicine Laboratories, School of Clinical Sciences, Cellular & Molecular Medicine, Medical Sciences Building, University Walk, University of Bristol, Bristol, BS8 1TD, UK. .,Institute of Medical Sciences & Technology, University of Kuala Lumpur, Kuala Lumpur, 43000, Malaysia.
| | - Helen Scott
- Regenerative Medicine Laboratories, School of Clinical Sciences, Cellular & Molecular Medicine, Medical Sciences Building, University Walk, University of Bristol, Bristol, BS8 1TD, UK.
| | - Mark Rogers
- Intelligent Systems Laboratory, Department of Engineering & Mathematics, Merchant Venturers Building, University of Bristol, Bristol, BS8 1UB, UK.
| | - Youn-Bok Lee
- MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry, London, UK.
| | - Jessica Gaunt
- Regenerative Medicine Laboratories, School of Clinical Sciences, Cellular & Molecular Medicine, Medical Sciences Building, University Walk, University of Bristol, Bristol, BS8 1TD, UK.
| | - Leonidas Phylactou
- Faculty of Computer and Information Science, University of Ljubljana, Trzaska cesta 25, SI-1001, Ljubljana, Slovenia.
| | - Tomaz Curk
- The Cyprus Institute of Neurology & Genetics, PO Box 23462, 1683, Nicosia, Cyprus.
| | - Colin Campbell
- Institute of Medical Sciences & Technology, University of Kuala Lumpur, Kuala Lumpur, 43000, Malaysia.
| | - Jernej Ule
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK.
| | - Michael Norman
- Regenerative Medicine Laboratories, School of Clinical Sciences, Cellular & Molecular Medicine, Medical Sciences Building, University Walk, University of Bristol, Bristol, BS8 1TD, UK.
| | - James B Uney
- Regenerative Medicine Laboratories, School of Clinical Sciences, Cellular & Molecular Medicine, Medical Sciences Building, University Walk, University of Bristol, Bristol, BS8 1TD, UK.
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Plank JL, Suflita MT, Galindo CL, Labosky PA. Transcriptional targets of Foxd3 in murine ES cells. Stem Cell Res 2013; 12:233-40. [PMID: 24270162 DOI: 10.1016/j.scr.2013.10.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Revised: 09/26/2013] [Accepted: 10/25/2013] [Indexed: 11/30/2022] Open
Abstract
Understanding gene regulatory networks controlling properties of pluripotent stem cells will facilitate development of stem cell-based therapies. The transcription factor Foxd3 is critical for maintenance of self-renewal, survival, and pluripotency in murine embryonic stem cells (ESCs). Using a conditional deletion of Foxd3 followed by gene expression analyses, we demonstrate that genes required for several developmental processes including embryonic organ development, epithelium development, and epithelial differentiation were misregulated in the absence of Foxd3. Additionally, we identified 6 novel targets of Foxd3 (Sox4, Safb, Sox15, Fosb, Pmaip1 and Smarcd3). Finally, we present data suggesting that Foxd3 functions upstream of genes required for skeletal muscle development. Together, this work provides further evidence that Foxd3 is a critical regulator of murine development through the regulation of lineage specific differentiation.
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Affiliation(s)
- Jennifer L Plank
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA; Center for Stem Cell Biology, Vanderbilt University, Nashville, TN, USA.
| | - Michael T Suflita
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA; Center for Stem Cell Biology, Vanderbilt University, Nashville, TN, USA
| | - Cristi L Galindo
- Department of Medicine, Vanderbilt University, Nashville, TN, USA
| | - Patricia A Labosky
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA; Center for Stem Cell Biology, Vanderbilt University, Nashville, TN, USA
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11
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Dieker J, Iglesias-Guimarais V, Décossas M, Stevenin J, Vlag J, Yuste VJ, Muller S. Early Apoptotic Reorganization of Spliceosomal Proteins Involves Caspases, CAD and Rearrangement of NuMA. Traffic 2011; 13:257-72. [DOI: 10.1111/j.1600-0854.2011.01307.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 10/21/2011] [Accepted: 10/21/2011] [Indexed: 01/18/2023]
Affiliation(s)
| | - Victoria Iglesias-Guimarais
- Cell Death, Senescence & Survival Research Group; Dept. Bioquimica i Biologia Molecular; Institut de Neurociències; Universitat Autònoma de Barcelona; Barcelona; Spain
| | - Marion Décossas
- Centre National de la Recherche Scientifique (CNRS); Institut de Biologie Moléculaire et Cellulaire; Strasbourg; France
| | - James Stevenin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC); Institut National de Santé et de Recherche Médicale (INSERM)/Centre National de Recherche Scientifique (CNRS); Université de Strasbourg; Illkirch; France
| | - Johan Vlag
- Nephrology Research Laboratory; Department of Nephrology; Nijmegen Centre for Molecular Life Sciences; Radboud University Nijmegen Medical Centre; Nijmegen; The Netherlands
| | - Victor J. Yuste
- Cell Death, Senescence & Survival Research Group; Dept. Bioquimica i Biologia Molecular; Institut de Neurociències; Universitat Autònoma de Barcelona; Barcelona; Spain
| | - Sylviane Muller
- Centre National de la Recherche Scientifique (CNRS); Institut de Biologie Moléculaire et Cellulaire; Strasbourg; France
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12
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Garee JP, Meyer R, Oesterreich S. Co-repressor activity of scaffold attachment factor B1 requires sumoylation. Biochem Biophys Res Commun 2011; 408:516-22. [PMID: 21527249 DOI: 10.1016/j.bbrc.2011.04.040] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 04/08/2011] [Indexed: 01/14/2023]
Abstract
Sumoylation is an emerging modification associated with a variety of cellular processes including the regulation of transcriptional activities of nuclear receptors and their coregulators. As SUMO modifications are often associated with transcriptional repression, we examined if sumoylation was involved in modulation of the transcriptional repressive activity of scaffold attachment factor B1. Here we show that SAFB1 is modified by both the SUMO1 and SUMO2/3 family of proteins, on lysine's K231 and K294. Further, we demonstrate that SAFB1 can interact with PIAS1, a SUMO E3 ligase which mediates SAFB1 sumoylation. Additionally, SENP1 was identified as the enzyme desumoylating SAFB1. Mutation of the SAFB1 sumoylation sites lead to a loss of transcriptional repression, at least in part due to decreased interaction with HDAC3, a known transcriptional repressor and SAFB1 binding partner. In summary, the transcriptional repressor SAFB1 is modified by both SUMO1 and SUMO2/3, and this modification is necessary for its full repressive activity.
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Affiliation(s)
- Jason P Garee
- Breast Center and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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13
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Garee JP, Oesterreich S. SAFB1's multiple functions in biological control-lots still to be done! J Cell Biochem 2010; 109:312-9. [PMID: 20014070 DOI: 10.1002/jcb.22420] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The examination of scaffold attachment factor B1 (SAFB1) and its multiple functions and tasks in cellular processes provides insight into its role in diseases, such as cancer. SAFB1 is a large multi-domain protein with well-described functions in transcriptional repression, and RNA splicing. It is ubiquitously expressed, and has been shown to be important in numerous cellular processes including cell growth, stress response, and apoptosis. SAFB1 is part of a protein family with at least two other family members, SAFB2 and the SAFB-like transcriptional modulator SLTM. The goal of this prospect article is to summarize known functions of SAFB1, and its roles in cellular processes, but also to speculate on less well described, novel attributes of SAFB1, such as a potential role in chromatin organization. This timely review shows aspects of SAFB1, which are proving to have a complexity far greater than was previously thought.
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Affiliation(s)
- Jason P Garee
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas, USA
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14
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Martijn C, Wiklund L. Effect of methylene blue on the genomic response to reperfusion injury induced by cardiac arrest and cardiopulmonary resuscitation in porcine brain. BMC Med Genomics 2010; 3:27. [PMID: 20594294 PMCID: PMC2904268 DOI: 10.1186/1755-8794-3-27] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 07/01/2010] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Cerebral ischemia/reperfusion injury is a common secondary effect of cardiac arrest which is largely responsible for postresuscitative mortality. Therefore development of therapies which restore and protect the brain function after cardiac arrest is essential. Methylene blue (MB) has been experimentally proven neuroprotective in a porcine model of global ischemia-reperfusion in experimental cardiac arrest. However, no comprehensive analyses have been conducted at gene expression level. METHODS Pigs underwent either untreated cardiac arrest (CA) or CA with subsequent cardiopulmonary resuscitation (CPR) accompanied with an infusion of saline or an infusion of saline with MB. Genome-wide transcriptional profiling using the Affymetrix porcine microarray was performed to 1) gain understanding of delayed neuronal death initiation in porcine brain during ischemia and after 30, 60 and 180 min following reperfusion, and 2) identify the mechanisms behind the neuroprotective effect of MB after ischemic injury (at 30, 60 and 180 min). RESULTS Our results show that restoration of spontaneous circulation (ROSC) induces major transcriptional changes related to stress response, inflammation, apoptosis and even cytoprotection. In contrast, the untreated ischemic and anoxic insult affected only few genes mainly involved in intra-/extracellular ionic balance. Furthermore, our data show that the neuroprotective role of MB is diverse and fulfilled by regulation of the expression of soluble guanylate cyclase and biological processes accountable for inhibition of apoptosis, modulation of stress response, neurogenesis and neuroprotection. CONCLUSIONS Our results support that MB could be a valuable intervention and should be investigated as a therapeutic agent against neural damage associated with I/R injury induced by cardiac arrest.
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Affiliation(s)
- Cécile Martijn
- Department of Surgical Sciences/Anaesthesiology and Intensive Care Medicine, Uppsala University Hospital, SE-751 85 Uppsala, Sweden
| | - Lars Wiklund
- Department of Surgical Sciences/Anaesthesiology and Intensive Care Medicine, Uppsala University Hospital, SE-751 85 Uppsala, Sweden
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15
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Alfonso-Parra C, Maggert KA. Drosophila SAF-B links the nuclear matrix, chromosomes, and transcriptional activity. PLoS One 2010; 5:e10248. [PMID: 20422039 PMCID: PMC2857882 DOI: 10.1371/journal.pone.0010248] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 03/26/2010] [Indexed: 02/06/2023] Open
Abstract
Induction of gene expression is correlated with alterations in nuclear organization, including proximity to other active genes, to the nuclear cortex, and to cytologically distinct domains of the nucleus. Chromosomes are tethered to the insoluble nuclear scaffold/matrix through interaction with Scaffold/Matrix Attachment Region (SAR/MAR) binding proteins. Identification and characterization of proteins involved in establishing or maintaining chromosome-scaffold interactions is necessary to understand how the nucleus is organized and how dynamic changes in attachment are correlated with alterations in gene expression. We identified and characterized one such scaffold attachment factor, a Drosophila homolog of mammalian SAF-B. The large nuclei and chromosomes of Drosophila have allowed us to show that SAF-B inhabits distinct subnuclear compartments, forms weblike continua in nuclei of salivary glands, and interacts with discrete chromosomal loci in interphase nuclei. These interactions appear mediated either by DNA-protein interactions, or through RNA-protein interactions that can be altered during changes in gene expression programs. Extraction of soluble nuclear proteins and DNA leaves SAF-B intact, showing that this scaffold/matrix-attachment protein is a durable component of the nuclear matrix. Together, we have shown that SAF-B links the nuclear scaffold, chromosomes, and transcriptional activity.
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Affiliation(s)
- Catalina Alfonso-Parra
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Keith A. Maggert
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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16
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Hammerich-Hille S, Kaipparettu BA, Tsimelzon A, Creighton CJ, Jiang S, Polo JM, Melnick A, Meyer R, Oesterreich S. SAFB1 mediates repression of immune regulators and apoptotic genes in breast cancer cells. J Biol Chem 2010; 285:3608-3616. [PMID: 19901029 PMCID: PMC2823501 DOI: 10.1074/jbc.m109.066431] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 11/04/2009] [Indexed: 12/18/2022] Open
Abstract
The scaffold attachment factors SAFB1 and SAFB2 are paralogs, which are involved in cell cycle regulation, apoptosis, differentiation, and stress response. They have been shown to function as estrogen receptor corepressors, and there is evidence for a role in breast tumorigenesis. To identify their endogenous target genes in MCF-7 breast cancer cells, we utilized a combined approach of chromatin immunoprecipitation (ChIP)-on-chip and gene expression array studies. By performing ChIP-on-chip on microarrays containing 24,000 promoters, we identified 541 SAFB1/SAFB2-binding sites in promoters of known genes, with significant enrichment on chromosomes 1 and 6. Gene expression analysis revealed that the majority of target genes were induced in the absence of SAFB1 or SAFB2 and less were repressed. Interestingly, there was no significant overlap between the genes identified by ChIP-on-chip and gene expression array analysis, suggesting regulation through regions outside the proximal promoters. In contrast to SAFB2, which shared most of its target genes with SAFB1, SAFB1 had many unique target genes, most of them involved in the regulation of the immune system. A subsequent analysis of the estrogen treatment group revealed that 12% of estrogen-regulated genes were dependent on SAFB1, with the majority being estrogen-repressed genes. These were primarily genes involved in apoptosis, such as BBC3, NEDD9, and OPG. Thus, this study confirms the primary role of SAFB1/SAFB2 as corepressors and also uncovers a previously unknown role for SAFB1 in the regulation of immune genes and in estrogen-mediated repression of genes.
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Affiliation(s)
- Stephanie Hammerich-Hille
- From the Lester and Sue Smith Breast Center, Department of Medicine and Molecular and Cellular Biology, Texas Children's Cancer Center, Houston, Texas 77030
| | - Benny A Kaipparettu
- From the Lester and Sue Smith Breast Center, Department of Medicine and Molecular and Cellular Biology, Texas Children's Cancer Center, Houston, Texas 77030
| | - Anna Tsimelzon
- From the Lester and Sue Smith Breast Center, Department of Medicine and Molecular and Cellular Biology, Texas Children's Cancer Center, Houston, Texas 77030
| | - Chad J Creighton
- From the Lester and Sue Smith Breast Center, Department of Medicine and Molecular and Cellular Biology, Texas Children's Cancer Center, Houston, Texas 77030
| | - Shiming Jiang
- From the Lester and Sue Smith Breast Center, Department of Medicine and Molecular and Cellular Biology, Texas Children's Cancer Center, Houston, Texas 77030
| | - Jose M Polo
- the Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Ari Melnick
- the Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Rene Meyer
- Department of Pediatric Hematology/Oncology, Texas Children's Cancer Center, Houston, Texas 77030 and
| | - Steffi Oesterreich
- From the Lester and Sue Smith Breast Center, Department of Medicine and Molecular and Cellular Biology, Texas Children's Cancer Center, Houston, Texas 77030; Department of Pediatric Hematology/Oncology, Texas Children's Cancer Center, Houston, Texas 77030 and.
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17
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Tsianou D, Nikolakaki E, Tzitzira A, Bonanou S, Giannakouros T, Georgatsou E. The enzymatic activity of SR protein kinases 1 and 1a is negatively affected by interaction with scaffold attachment factors B1 and 2. FEBS J 2009; 276:5212-27. [PMID: 19674106 DOI: 10.1111/j.1742-4658.2009.07217.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
SR protein kinases (SRPKs) phosphorylate Ser/Arg dipeptide-containing proteins that play crucial roles in a broad spectrum of basic cellular processes. Phosphorylation by SRPKs constitutes a major way of regulating such cellular mechanisms. In the past, we have shown that SRPK1a interacts with the nuclear matrix protein scaffold attachment factor B1 (SAFB1) via its unique N-terminal domain, which differentiates it from SRPK1. In this study, we show that SAFB1 inhibits the activity of both SRPK1a and SRPK1 in vitro and that its RE-rich region is redundant for the observed inhibition. We demonstrate that kinase activity inhibition is caused by direct binding of SAFB1 to SRPK1a and SRPK1, and we also present evidence for the in vitro binding of SAFB2 to the two kinases, albeit with different affinity. Moreover, we show that both SR protein kinases can form complexes with both scaffold attachment factors B in living cells and that this interaction is capable of inhibiting their activity, depending on the tenacity of the complex formed. Finally, we present data demonstrating that SRPK/SAFB complexes are present in the nucleus of HeLa cells and that the enzymatic activity of the nuclear matrixlocalized SRPK1 is repressed. These results suggest a new role for SAFB proteins as regulators of SRPK activity and underline the importance of the assembly of transient intranuclear complexes in cellular regulation.
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Affiliation(s)
- Dora Tsianou
- Department of Medicine, University of Thessaly, Mezourlo, 41110 Larissa, Greece
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Low SAFB levels are associated with worse outcome in breast cancer patients. Breast Cancer Res Treat 2009; 121:503-9. [PMID: 19137425 DOI: 10.1007/s10549-008-0297-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 12/23/2008] [Indexed: 10/21/2022]
Abstract
The scaffold attachment factors SAFB1 and SAFB2 have been shown to function as estrogen receptor (ERalpha) co-repressors in breast cancer cells, and to affect many cellular processes such as stress response, RNA processing, and apoptosis. SAFB1 and SAFB2 have also been implicated in breast tumorigenesis: Their shared chromosomal locus at 19p13 is frequently lost in breast cancer, mutations have been identified, and overexpression results in growth inhibition. The purpose of this study was to determine SAFB1/SAFB2 protein expression in human breast tumors, to correlate their expression with either natural progression ("prognostic factor") or with response to Tamoxifen ("predictive factor"), and to analyze potential correlations with tumor characteristics. SAFB1/SAFB2 protein were measured by immunoblotting using a pan-SAFB antibody in tumor extracts from patients with long-term clinical follow-up (n = 289), a subset of whom had received no adjuvant systemic therapy after breast cancer surgery (n = 117) and another subset of whom were treated with adjuvant Tamoxifen (n = 172). SAFB levels were correlated with clinico-pathological variables and patient outcome. SAFB levels varied widely, with 25 tumors not expressing detectable levels of SAFB. SAFB expression was significantly correlated with ERalpha, HER-2, bcl-2 and with expression of other ERalpha coregulators such as SRC-3. There was no association between SAFB expression and disease free survival, however, low SAFB expression was significantly associated with worse overall survival in patients who did not receive adjuvant therapy. This study shows that low SAFB protein levels predict poor prognosis of breast cancer patients, suggesting critical functions of SAFB1 and SAFB2 in breast cancer cells.
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