1
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Wu D, Van der Hoeven G, Claes Z, Van Eynde A, Bollen M. DNA damage-induced allosteric activation of protein phosphatase PP1:NIPP1 through Src kinase-induced circularization of NIPP1. FEBS J 2024; 291:2615-2635. [PMID: 38303113 DOI: 10.1111/febs.17064] [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: 07/03/2023] [Revised: 12/06/2023] [Accepted: 12/28/2023] [Indexed: 02/03/2024]
Abstract
Protein phosphatase-1 (PP1) complexed to nuclear inhibitor of PP1 (NIPP1) limits DNA repair through dephosphorylation of NIPP1-recruited substrates. However, the PP1:NIPP1 holoenzyme is completely inactive under basal conditions, hinting at a DNA damage-regulated activation mechanism. Here, we report that DNA damage caused the activation of PP1:NIPP1 after a time delay of several hours through phosphorylation of NIPP1 at the C-terminal tyrosine 335 (Y335) by a Src-family kinase. PP1:NIPP1 activation partially resulted from the dissociation of the C terminus of NIPP1 from the active site of PP1. In addition, the released Y335-phosphorylated C terminus interacted with the N terminus of NIPP1 to enhance substrate recruitment by the flanking forkhead-associated (FHA) domain. Constitutive activation of PP1:NIPP1 by knock-in of a phospho-mimicking (Y335E) NIPP1 mutant led to the hypo-phosphorylation of FHA ligands and an accumulation of DNA double-strand breaks. Our data indicate that PP1:NIPP1 activation through circularization of NIPP1 is a late response to DNA damage that contributes to the timely recovery from damage repair.
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Affiliation(s)
- Dan Wu
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
| | - Gerd Van der Hoeven
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
| | - Zander Claes
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Belgium
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2
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Tang Y, Zhang B, Shi H, Yan Z, Wang P, Yang Q, Huang X, Gun S. Molecular characterization, expression patterns and cellular localization of BCAS2 gene in male Hezuo pig. PeerJ 2023; 11:e16341. [PMID: 37901468 PMCID: PMC10607209 DOI: 10.7717/peerj.16341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 10/03/2023] [Indexed: 10/31/2023] Open
Abstract
Background Breast carcinoma amplified sequence 2 (BCAS2) participates in pre-mRNA splicing and DNA damage response, which is implicated in spermatogenesis and meiosis initiation in mouse. Nevertheless, the physiological roles of BCAS2 in the testes of large mammals especially boars remain largely unknown. Methods In this study, testes were collected from Hezuo pig at three development stages including 30 days old (30 d), 120 days old (120 d), and 240 days old (240 d). BCAS2 CDS region was firstly cloned using RT-PCR method, and its molecular characteristics were identified using relevant bioinformatics software. Additionally, the expression patterns and cellular localization of BCAS2 were analyzed by quantitative real-time PCR (qRT-PCR), Western blot, immunohistochemistry and immunofluorescence. Results The cloning and sequence analysis indicated that the Hezuo pig BCAS2 CDS fragment encompassed 678 bp open reading frame (ORF) capable of encoding 225 amino acid residues, and possessed high identities with some other mammals. The results of qRT-PCR and Western blot displayed that BCAS2 levels both mRNA and protein were age-dependent increased (p < 0.01). Additionally, immunohistochemistry and immunofluorescence results revealed that BCAS2 protein was mainly observed in nucleus of gonocytes at 30 d testes as well as nucleus of spermatogonia and Sertoli cells at 120 and 240 d testes. Accordingly, we conclude that BCAS2 is critical for testicular development and spermatogenesis of Hezuo pig, perhaps by regulating proliferation or differentiation of gonocytes, pre-mRNA splicing of spermatogonia and functional maintenance of Sertoli cells, but specific mechanism still requires be further investigated.
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Affiliation(s)
- Yuran Tang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Bo Zhang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Haixia Shi
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Zunqiang Yan
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Pengfei Wang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Qiaoli Yang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Xiaoyu Huang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China
| | - Shuangbao Gun
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, Gansu, China
- Gansu Research Center for Swine Production Engineering and Technology, Lanzhou, Gansu, China
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3
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Kow RL, Black AH, Henderson BP, Kraemer BC. Sut-6/NIPP1 modulates tau toxicity. Hum Mol Genet 2023; 32:2292-2306. [PMID: 37000013 PMCID: PMC10321383 DOI: 10.1093/hmg/ddad049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 03/04/2023] [Accepted: 03/27/2023] [Indexed: 04/01/2023] Open
Abstract
Neurodegenerative diseases exhibiting the pathological accumulation of tau such as Alzheimer's disease and related disorders still have no disease-modifying treatments and the molecular mechanisms of neurodegeneration remain unclear. To discover additional suppressor of tauopathy (sut) genes that mediate or modulate the toxicity of pathological tau, we performed a classical genetic screen using a tau transgenic Caenorhabditis elegans model. From this screen, we identified the suppressing mutation W292X in sut-6, the C. elegans homolog of human NIPP1, which truncates the C-terminal RNA-binding domain. Using CRISPR-based genome editing approaches, we generated null and additional C-terminally truncated alleles in sut-6 and found that loss of sut-6 or sut-6(W292X) suppresses tau-induced behavioral locomotor deficits, tau protein accumulation and neuron loss. The sut-6(W292X) mutation showed stronger and semi-dominant suppression of tau toxicity while sut-6 deletion acted recessively. Neuronal overexpression of SUT-6 protein did not significantly alter tau toxicity, but neuronal overexpression of SUT-6 W292X mutant protein reduced tau-mediated deficits. Epistasis studies showed tauopathy suppression by sut-6 occurs independent of other known nuclear speckle-localized suppressors of tau such as sut-2, aly-1/aly-3 and spop-1. In summary, we have shown that sut-6/NIPP1 modulates tau toxicity and found a dominant mutation in the RNA-binding domain of sut-6 which strongly suppresses tau toxicity. This suggests that altering RNA-related functions of SUT-6/NIPP1 instead of complete loss of SUT-6/NIPP1 will provide the strongest suppression of tau.
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Affiliation(s)
- R L Kow
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA 98104, USA
| | - A H Black
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
| | - B P Henderson
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
| | - B C Kraemer
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA 98104, USA
- Department of Psychiatry and Behavioral Sciences
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
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4
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Patil RS, Kovacs-Kasa A, Gorshkov BA, Fulton DJR, Su Y, Batori RK, Verin AD. Serine/Threonine Protein Phosphatases 1 and 2A in Lung Endothelial Barrier Regulation. Biomedicines 2023; 11:1638. [PMID: 37371733 PMCID: PMC10296329 DOI: 10.3390/biomedicines11061638] [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: 05/04/2023] [Revised: 05/28/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Vascular barrier dysfunction is characterized by increased permeability and inflammation of endothelial cells (ECs), which are prominent features of acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and sepsis, and a major complication of the SARS-CoV-2 infection and COVID-19. Functional impairment of the EC barrier and accompanying inflammation arises due to microbial toxins and from white blood cells of the lung as part of a defensive action against pathogens, ischemia-reperfusion or blood product transfusions, and aspiration syndromes-based injury. A loss of barrier function results in the excessive movement of fluid and macromolecules from the vasculature into the interstitium and alveolae resulting in pulmonary edema and collapse of the architecture and function of the lungs, and eventually culminates in respiratory failure. Therefore, EC barrier integrity, which is heavily dependent on cytoskeletal elements (mainly actin filaments, microtubules (MTs), cell-matrix focal adhesions, and intercellular junctions) to maintain cellular contacts, is a critical requirement for the preservation of lung function. EC cytoskeletal remodeling is regulated, at least in part, by Ser/Thr phosphorylation/dephosphorylation of key cytoskeletal proteins. While a large body of literature describes the role of phosphorylation of cytoskeletal proteins on Ser/Thr residues in the context of EC barrier regulation, the role of Ser/Thr dephosphorylation catalyzed by Ser/Thr protein phosphatases (PPases) in EC barrier regulation is less documented. Ser/Thr PPases have been proposed to act as a counter-regulatory mechanism that preserves the EC barrier and opposes EC contraction. Despite the importance of PPases, our knowledge of the catalytic and regulatory subunits involved, as well as their cellular targets, is limited and under-appreciated. Therefore, the goal of this review is to discuss the role of Ser/Thr PPases in the regulation of lung EC cytoskeleton and permeability with special emphasis on the role of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) as major mammalian Ser/Thr PPases. Importantly, we integrate the role of PPases with the structural dynamics of the cytoskeleton and signaling cascades that regulate endothelial cell permeability and inflammation.
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Affiliation(s)
- Rahul S. Patil
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Anita Kovacs-Kasa
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Boris A. Gorshkov
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - David J. R. Fulton
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Yunchao Su
- Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Robert K. Batori
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Alexander D. Verin
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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5
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Wang Q. The role of forkhead-associated (FHA)-domain proteins in plant biology. PLANT MOLECULAR BIOLOGY 2023; 111:455-472. [PMID: 36849846 DOI: 10.1007/s11103-023-01338-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
The forkhead-associated (FHA) domain, a well-characterized small protein module that mediates protein-protein interactions by targeting motifs containing phosphothreonine, is present in many regulatory molecules like protein kinase, phosphatases, transcription factors, and other functional proteins. FHA-domain containing proteins in yeast and human are involved in a large variety of cellular processes such as DNA repair, cell cycle arrest, or pre-mRNA processing. Since the first FHA-domain protein, kinase-associated protein phosphatase (KAPP) was found in plants, the interest in plant FHA-containing proteins has increased dramatically, mainly due to the important role of FHA domain-containing proteins in plant growth and development. In this review, we provide a comprehensive overview of the fundamental properties of FHA domain-containing proteins in plants, and systematically summarized and analyzed the research progress of proteins containing the FHA domain in plants. We also emphasized that AT5G47790 and its homologs may play an important role as the regulatory subunit of protein phosphatase 1 (PP1) in plants.
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Affiliation(s)
- Qiuling Wang
- Institute of Future Agriculture, State Key Laboratory of Crop Stress Biology for Arid Areas, State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
- Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China.
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6
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CDC5L promotes early chondrocyte differentiation and proliferation by modulating pre-mRNA splicing of SOX9, COL2A1, and WEE1. J Biol Chem 2021; 297:100994. [PMID: 34298017 PMCID: PMC8363834 DOI: 10.1016/j.jbc.2021.100994] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 07/12/2021] [Accepted: 07/19/2021] [Indexed: 11/23/2022] Open
Abstract
Ossification of the posterior longitudinal ligament (OPLL) of the spine is a common pathological condition that causes intractable myelopathy and radiculopathy, mainly the result of an endochondral ossification-like process. Our previous genome-wide association study identified six susceptibility loci for OPLL, including the cell division cycle 5-like (CDC5L) gene region. Here, we found CDC5L to be expressed in type II collagen-producing chondrocyte-like fibroblasts in human OPLL specimens, as well as in differentiating ATDC5 chondrocytes. Cdc5l siRNA transfection in murine chondrocytes decreased the expression of the early chondrogenic genes Sox9 and Col2a1, diminished the cartilage matrix production, and enhanced the expression of parathyroid-hormone-related protein (a resting chondrocyte marker). We also showed that Cdc5l shRNA suppressed the growth of cultured murine embryonal metatarsal cartilage rudiments and that Cdc5l knockdown suppressed the growth of ATDC5 cells. Fluorescence-activated cell sorting analysis revealed that the G2/M cell cycle transition was blocked; our data showed that Cdc5l siRNA transfection enhanced expression of Wee1, an inhibitor of the G2/M transition. Cdc5l siRNA also decreased the pre-mRNA splicing efficiency of Sox9 and Col2a1 genes in both ATDC5 cells and primary chondrocytes; conversely, loss of Cdc5l resulted in enhanced splicing of Wee1 pre-mRNA. Finally, an RNA-binding protein immunoprecipitation assay revealed that Cdc5l bound directly to these target gene transcripts. Overall, we conclude that Cdc5l promotes both early chondrogenesis and cartilage growth and may play a role in the etiology of OPLL, at least in part by fine-tuning the pre-mRNA splicing of chondrogenic genes and Wee1, thus initiating the endochondral ossification process.
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7
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Zhang HY, Li J, Ouyang YC, Meng TG, Zhang CH, Yue W, Sun QY, Qian WP. Cell Division Cycle 5-Like Regulates Metaphase-to-Anaphase Transition in Meiotic Oocyte. Front Cell Dev Biol 2021; 9:671685. [PMID: 34277613 PMCID: PMC8282184 DOI: 10.3389/fcell.2021.671685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/30/2021] [Indexed: 11/13/2022] Open
Abstract
The quality of oocytes is a vital factor for embryo development. Meiotic progression through metaphase I usually takes a relatively long time to ensure correct chromosome separation, a process that is critical for determining oocyte quality. Here, we report that cell division cycle 5-like (Cdc5L) plays a critical role in regulating metaphase-to-anaphase I transition during mouse oocyte meiotic maturation. Knockdown of Cdc5L by small interfering RNA injection did not affect spindle assembly but caused metaphase I arrest and subsequent reduced first polar body extrusion due to insufficient anaphase-promoting complex/cyclosome activity. We further showed that Cdc5L could also directly interact with securin, and Cdc5L knockdown led to a continuous high expression level of securin, causing severely compromised meiotic progression. The metaphase-to-anaphase I arrest caused by Cdc5L knockdown could be rescued by knockdown of endogenous securin. In summary, we reveal a novel role for Cdc5L in regulating mouse oocyte meiotic progression by interacting with securin.
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Affiliation(s)
- Hong-Yong Zhang
- Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China.,State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,Guangdong Key Laboratory of Male Reproductive Medicine and Genetics, Shenzhen PKU-HKUST Medical Center, Institute of Urology, Peking University Shenzhen Hospital, Shenzhen, China
| | - Jian Li
- Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China
| | - Ying-Chun Ouyang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Tie-Gang Meng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, China
| | - Chun-Hui Zhang
- Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China
| | - Wei Yue
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Qing-Yuan Sun
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, China
| | - Wei-Ping Qian
- Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China.,Guangdong Key Laboratory of Male Reproductive Medicine and Genetics, Shenzhen PKU-HKUST Medical Center, Institute of Urology, Peking University Shenzhen Hospital, Shenzhen, China
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8
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Hanaki S, Habara M, Masaki T, Maeda K, Sato Y, Nakanishi M, Shimada M. PP1 regulatory subunit NIPP1 regulates transcription of E2F1 target genes following DNA damage. Cancer Sci 2021; 112:2739-2752. [PMID: 33939241 PMCID: PMC8253265 DOI: 10.1111/cas.14924] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/14/2021] [Accepted: 04/14/2021] [Indexed: 12/21/2022] Open
Abstract
DNA damage induces transcriptional repression of E2F1 target genes and a reduction in histone H3‐Thr11 phosphorylation (H3‐pThr11) at E2F1 target gene promoters. Dephosphorylation of H3‐pThr11 is partly mediated by Chk1 kinase and protein phosphatase 1γ (PP1γ) phosphatase. Here, we isolated NIPP1 as a regulator of PP1γ‐mediated H3‐pThr11 by surveying nearly 200 PP1 interactor proteins. We found that NIPP1 inhibits PP1γ‐mediated dephosphorylation of H3‐pThr11 both in vivo and in vitro. By generating NIPP1‐depleted cells, we showed that NIPP1 is required for cell proliferation and the expression of E2F1 target genes. Upon DNA damage, activated protein kinase A (PKA) phosphorylated the NIPP1‐Ser199 residue, adjacent to the PP1 binding motif (RVxF), and triggered the dissociation of NIPP1 from PP1γ, leading to the activation of PP1γ. Furthermore, the inhibition of PKA activity led to the activation of E2F target genes. Statistical analysis confirmed that the expression of NIPP1 was positively correlated with E2F target genes. Taken together, these findings demonstrate that the PP1 regulatory subunit NIPP1 modulates E2F1 target genes by linking PKA and PP1γ during DNA damage.
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Affiliation(s)
- Shunsuke Hanaki
- Department of Biochemistry, Joint Faculty of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Makoto Habara
- Department of Biochemistry, Joint Faculty of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Takahiro Masaki
- Department of Biochemistry, Joint Faculty of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Keisuke Maeda
- Department of Biochemistry, Joint Faculty of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Yuki Sato
- Department of Biochemistry, Joint Faculty of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
| | - Makoto Nakanishi
- Division of Cancer Biology, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Midori Shimada
- Department of Biochemistry, Joint Faculty of Veterinary Science, Yamaguchi University, Yamaguchi, Japan
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9
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Fedoryshchak RO, Přechová M, Butler AM, Lee R, O'Reilly N, Flynn HR, Snijders AP, Eder N, Ultanir S, Mouilleron S, Treisman R. Molecular basis for substrate specificity of the Phactr1/PP1 phosphatase holoenzyme. eLife 2020; 9:61509. [PMID: 32975518 PMCID: PMC7599070 DOI: 10.7554/elife.61509] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 09/24/2020] [Indexed: 01/01/2023] Open
Abstract
PPP-family phosphatases such as PP1 have little intrinsic specificity. Cofactors can target PP1 to substrates or subcellular locations, but it remains unclear how they might confer sequence-specificity on PP1. The cytoskeletal regulator Phactr1 is a neuronally enriched PP1 cofactor that is controlled by G-actin. Structural analysis showed that Phactr1 binding remodels PP1's hydrophobic groove, creating a new composite surface adjacent to the catalytic site. Using phosphoproteomics, we identified mouse fibroblast and neuronal Phactr1/PP1 substrates, which include cytoskeletal components and regulators. We determined high-resolution structures of Phactr1/PP1 bound to the dephosphorylated forms of its substrates IRSp53 and spectrin αII. Inversion of the phosphate in these holoenzyme-product complexes supports the proposed PPP-family catalytic mechanism. Substrate sequences C-terminal to the dephosphorylation site make intimate contacts with the composite Phactr1/PP1 surface, which are required for efficient dephosphorylation. Sequence specificity explains why Phactr1/PP1 exhibits orders-of-magnitude enhanced reactivity towards its substrates, compared to apo-PP1 or other PP1 holoenzymes.
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Affiliation(s)
- Roman O Fedoryshchak
- Signalling and Transcription Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Magdalena Přechová
- Signalling and Transcription Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Abbey M Butler
- Signalling and Transcription Laboratory, The Francis Crick Institute, London, United Kingdom.,Structural Biology Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Rebecca Lee
- Signalling and Transcription Laboratory, The Francis Crick Institute, London, United Kingdom.,Structural Biology Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Nicola O'Reilly
- Peptide Chemistry Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Helen R Flynn
- Proteomics Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Ambrosius P Snijders
- Proteomics Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Noreen Eder
- Proteomics Science Technology Platform, The Francis Crick Institute, London, United Kingdom.,Kinases and Brain Development Laboratory The Francis Crick Institute, London, United Kingdom
| | - Sila Ultanir
- Kinases and Brain Development Laboratory The Francis Crick Institute, London, United Kingdom
| | - Stephane Mouilleron
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Richard Treisman
- Signalling and Transcription Laboratory, The Francis Crick Institute, London, United Kingdom
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10
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Petasny M, Bentata M, Pawellek A, Baker M, Kay G, Salton M. Splicing to Keep Cycling: The Importance of Pre-mRNA Splicing during the Cell Cycle. Trends Genet 2020; 37:266-278. [PMID: 32950269 DOI: 10.1016/j.tig.2020.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/09/2020] [Accepted: 08/18/2020] [Indexed: 12/16/2022]
Abstract
Pre-mRNA splicing is a fundamental process in mammalian gene expression, and alternative splicing plays an extensive role in generating protein diversity. Because the majority of genes undergo pre-mRNA splicing, most cellular processes depend on proper spliceosome function. We focus on the cell cycle and describe its dependence on pre-mRNA splicing and accurate alternative splicing. We outline the key cell-cycle factors and their known alternative splicing isoforms. We discuss different levels of pre-mRNA splicing regulation such as post-translational modifications and changes in the expression of splicing factors. We describe the effect of chromatin dynamics on pre-mRNA splicing during the cell cycle. In addition, we focus on spliceosome component SF3B1, which is mutated in many types of cancer, and describe the link between SF3B1 and its inhibitors and the cell cycle.
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Affiliation(s)
- Mayra Petasny
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Mercedes Bentata
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Andrea Pawellek
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK
| | - Mai Baker
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Gillian Kay
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Maayan Salton
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel.
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11
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Enhanced DNA-repair capacity and resistance to chemically induced carcinogenesis upon deletion of the phosphatase regulator NIPP1. Oncogenesis 2020; 9:30. [PMID: 32123159 PMCID: PMC7051951 DOI: 10.1038/s41389-020-0214-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 11/16/2022] Open
Abstract
Nuclear Inhibitor of PP1 (NIPP1) is a conserved regulatory subunit of protein phosphatase PP1. The selective deletion of NIPP1 in mouse liver parenchymal cells or skin epidermal cells culminates in a late-onset hyperproliferation of a subset of resident progenitor cells. Although a hyperplastic phenotype is usually tumor promoting, we show here that the absence of NIPP1 conferred a strong resistance to chemically induced hepatocellular or skin carcinoma. The ablation of NIPP1 did not affect the metabolism of the administered mutagens (diethylnitrosamine or 7,12-dimethylbenz[a]anthracene), but reduced the conversion of mutagen-induced covalent DNA modifications into cancer-initiating mutations. This reduced sensitivity to mutagens correlated with an enhanced DNA-damage response and an augmented expression of rate-limiting DNA-repair proteins (MGMT in liver, XPD and XPG in skin), hinting at an increased DNA-repair capacity. Our data identify NIPP1 as a repressor of DNA repair and as a promising target for novel cancer prevention and treatment therapies.
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12
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Phosphatase Regulator NIPP1 Restrains Chemokine-Driven Skin Inflammation. J Invest Dermatol 2020; 140:1576-1588. [PMID: 31972250 DOI: 10.1016/j.jid.2020.01.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/20/2019] [Accepted: 01/05/2020] [Indexed: 02/06/2023]
Abstract
Nuclear inhibitor of protein phosphatase 1 (NIPP1) is a ubiquitously expressed nuclear protein that regulates functions of protein serine/threonine phosphatase-1 in cell proliferation and lineage specification. The role of NIPP1 in tissue homeostasis is not fully understood. This study shows that the selective deletion of NIPP1 in mouse epidermis resulted in epidermal hyperproliferation, a reduced adherence of basal keratinocytes, and a gradual decrease in the stemness of hair follicle stem cells, culminating in hair loss. This complex phenotype was associated with chronic sterile skin inflammation and could be partially rescued by dexamethasone treatment. NIPP1-deficient keratinocytes massively expressed proinflammatory chemokines and immunomodulatory proteins in a cell-autonomous manner. Chemokines subsequently induced the recruitment and activation of immune cells, in particular conventional dendritic cells and Langerhans cells, accounting for the chronic inflammation phenotype. The data identifies NIPP1 as a key regulator of epidermal homeostasis and as a potential target for the treatment of inflammatory skin diseases.
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13
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Wu D, De Wever V, Derua R, Winkler C, Beullens M, Van Eynde A, Bollen M. A substrate-trapping strategy for protein phosphatase PP1 holoenzymes using hypoactive subunit fusions. J Biol Chem 2018; 293:15152-15162. [PMID: 30115685 DOI: 10.1074/jbc.ra118.004132] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 08/13/2018] [Indexed: 01/24/2023] Open
Abstract
The protein Ser/Thr phosphatase PP1 catalyzes an important fraction of protein dephosphorylation events and forms highly specific holoenzymes through an association with regulatory interactors of protein phosphatase one (RIPPOs). The functional characterization of individual PP1 holoenzymes is hampered by the lack of straightforward strategies for substrate mapping. Because efficient substrate recruitment often involves binding to both PP1 and its associated RIPPO, here we examined whether PP1-RIPPO fusions can be used to trap substrates for further analysis. Fusions of an hypoactive point mutant of PP1 and either of four tested RIPPOs accumulated in HEK293T cells with their associated substrates and were co-immunoprecipitated for subsequent identification of the substrates by immunoblotting or MS analysis. Hypoactive fusions were also used to study RIPPOs themselves as substrates for associated PP1. In contrast, substrate trapping was barely detected with active PP1-RIPPO fusions or with nonfused PP1 or RIPPO subunits. Our results suggest that hypoactive fusions of PP1 subunits represent an easy-to-use tool for substrate identification of individual holoenzymes.
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Affiliation(s)
- Dan Wu
- From the Laboratory of Biosignaling and Therapeutics
| | | | - Rita Derua
- the Protein Phosphorylation and Proteomics Lab, KU Leuven Department of Cellular and Molecular Medicine, and.,SyBioMa, University of Leuven, 3000 Leuven, Belgium
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14
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Winkler C, Rouget R, Wu D, Beullens M, Van Eynde A, Bollen M. Overexpression of PP1-NIPP1 limits the capacity of cells to repair DNA double-strand breaks. J Cell Sci 2018; 131:jcs.214932. [PMID: 29898919 DOI: 10.1242/jcs.214932] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 05/29/2018] [Indexed: 12/20/2022] Open
Abstract
The ubiquitously expressed nuclear protein NIPP1 (also known as PPP1R8) recruits phosphoproteins for regulated dephosphorylation by the associated protein phosphatase PP1. To bypass the PP1 titration artifacts seen upon NIPP1 overexpression, we have engineered covalently linked fusions of PP1 and NIPP1, and demonstrate their potential to selectively explore the function of the PP1:NIPP1 holoenzyme. By using inducible stable cell lines, we show that PP1-NIPP1 fusions cause replication stress in a manner that requires both PP1 activity and substrate recruitment via the ForkHead Associated domain of NIPP1. More specifically, PP1-NIPP1 expression resulted in the build up of RNA-DNA hybrids (R-loops), enhanced chromatin compaction and a diminished repair of DNA double-strand breaks (DSBs), culminating in the accumulation of DSBs. These effects were associated with a reduced expression of DNA damage signaling and repair proteins. Our data disclose a key role for dephosphorylation of PP1:NIPP1 substrates in setting the threshold for DNA repair, and indicate that activators of this phosphatase hold therapeutic potential as sensitizers for DNA-damaging agents.
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Affiliation(s)
- Claudia Winkler
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Raphael Rouget
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Dan Wu
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Monique Beullens
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
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15
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Li X, Wang X, Song W, Xu H, Huang R, Wang Y, Zhao W, Xiao Z, Yang X. Oncogenic Properties of NEAT1 in Prostate Cancer Cells Depend on the CDC5L–AGRN Transcriptional Regulation Circuit. Cancer Res 2018; 78:4138-4149. [DOI: 10.1158/0008-5472.can-18-0688] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 04/23/2018] [Accepted: 05/31/2018] [Indexed: 11/16/2022]
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16
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Vohwinkel CU, Buchäckert Y, Al-Tamari HM, Mazzocchi LC, Eltzschig HK, Mayer K, Morty RE, Herold S, Seeger W, Pullamsetti SS, Vadász I. Restoration of Megalin-Mediated Clearance of Alveolar Protein as a Novel Therapeutic Approach for Acute Lung Injury. Am J Respir Cell Mol Biol 2017; 57:589-602. [PMID: 28678521 DOI: 10.1165/rcmb.2016-0358oc] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Acute respiratory distress syndrome constitutes a significant disease burden with regard to both morbidity and mortality. Current therapies are mostly supportive and do not address the underlying pathophysiologic mechanisms. Removal of protein-rich alveolar edema-a clinical hallmark of acute respiratory distress syndrome-is critical for survival. Here, we describe a transforming growth factor (TGF)-β-triggered mechanism, in which megalin, the primary mediator of alveolar protein transport, is negatively regulated by glycogen synthase kinase (GSK) 3β, with protein phosphatase 1 and nuclear inhibitor of protein phosphatase 1 being involved in the signaling cascade. Inhibition of GSK3β rescued transepithelial protein clearance in primary alveolar epithelial cells after TGF-β treatment. Moreover, in a bleomycin-based model of acute lung injury, megalin+/- animals (the megalin-/- variant is lethal due to postnatal respiratory failure) showed a marked increase in intra-alveolar protein and more severe lung injury compared with wild-type littermates. In contrast, wild-type mice treated with the clinically relevant GSK3β inhibitors, tideglusib and valproate, exhibited significantly decreased alveolar protein concentrations, which was associated with improved lung function and histopathology. Together, we discovered that the TGF-β-GSK3β-megalin axis is centrally involved in disturbances of alveolar protein clearance in acute lung injury and provide preclinical evidence for therapeutic efficacy of GSK3β inhibition.
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Affiliation(s)
- Christine U Vohwinkel
- 1 Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Giessen, Germany.,2 Department of Pediatrics, University of Colorado at Denver, Aurora, Colorado
| | - Yasmin Buchäckert
- 1 Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Giessen, Germany
| | - Hamza M Al-Tamari
- 3 Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; and
| | - Luciana C Mazzocchi
- 1 Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Giessen, Germany
| | - Holger K Eltzschig
- 4 Organ Protection Program, Department of Anesthesiology, University of Colorado at Denver, Aurora, Colorado
| | - Konstantin Mayer
- 1 Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Giessen, Germany
| | - Rory E Morty
- 1 Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Giessen, Germany.,3 Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; and
| | - Susanne Herold
- 1 Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Giessen, Germany
| | - Werner Seeger
- 1 Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Giessen, Germany.,3 Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; and
| | - Soni S Pullamsetti
- 3 Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; and
| | - István Vadász
- 1 Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Giessen, Germany
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17
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The protein phosphatase 1 regulator NIPP1 is essential for mammalian spermatogenesis. Sci Rep 2017; 7:13364. [PMID: 29042623 PMCID: PMC5645368 DOI: 10.1038/s41598-017-13809-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 09/29/2017] [Indexed: 12/22/2022] Open
Abstract
NIPP1 is one of the major nuclear interactors of protein phosphatase PP1. The deletion of NIPP1 in mice is early embryonic lethal, which has precluded functional studies in adult tissues. Hence, we have generated an inducible NIPP1 knockout model using a tamoxifen-inducible Cre recombinase transgene. The inactivation of the NIPP1 encoding alleles (Ppp1r8) in adult mice occurred very efficiently in testis and resulted in a gradual loss of germ cells, culminating in a Sertoli-cell only phenotype. Before the overt development of this phenotype Ppp1r8−/− testis showed a decreased proliferation and survival capacity of cells of the spermatogenic lineage. A reduced proliferation was also detected after the tamoxifen-induced removal of NIPP1 from cultured testis slices and isolated germ cells enriched for undifferentiated spermatogonia, hinting at a testis-intrinsic defect. Consistent with the observed phenotype, RNA sequencing identified changes in the transcript levels of cell-cycle and apoptosis regulating genes in NIPP1-depleted testis. We conclude that NIPP1 is essential for mammalian spermatogenesis because it is indispensable for the proliferation and survival of progenitor germ cells, including (un)differentiated spermatogonia.
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18
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De Munter S, Görnemann J, Derua R, Lesage B, Qian J, Heroes E, Waelkens E, Van Eynde A, Beullens M, Bollen M. Split-BioID: a proximity biotinylation assay for dimerization-dependent protein interactions. FEBS Lett 2017; 591:415-424. [DOI: 10.1002/1873-3468.12548] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 12/03/2016] [Accepted: 12/26/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Sofie De Munter
- Laboratory of Biosignaling & Therapeutics; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
| | - Janina Görnemann
- Laboratory of Biosignaling & Therapeutics; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
| | - Rita Derua
- Protein Phosphorylation & Proteomics Lab; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
- SyBioMa; KU Leuven; Belgium
| | - Bart Lesage
- Laboratory of Biosignaling & Therapeutics; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
| | - Junbin Qian
- Laboratory of Biosignaling & Therapeutics; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
| | - Ewald Heroes
- Laboratory of Biosignaling & Therapeutics; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
| | - Etienne Waelkens
- Protein Phosphorylation & Proteomics Lab; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
- SyBioMa; KU Leuven; Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
| | - Monique Beullens
- Laboratory of Biosignaling & Therapeutics; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics; KU Leuven Department of Cellular and Molecular Medicine; University of Leuven; Belgium
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19
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Towards understanding pre-mRNA splicing mechanisms and the role of SR proteins. Gene 2016; 587:107-19. [PMID: 27154819 DOI: 10.1016/j.gene.2016.04.057] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 04/30/2016] [Indexed: 01/04/2023]
Abstract
Alternative pre-mRNA splicing provides a source of vast protein diversity by removing non-coding sequences (introns) and accurately linking different exonic regions in the correct reading frame. The regulation of alternative splicing is essential for various cellular functions in both pathological and physiological conditions. In eukaryotic cells, this process is commonly used to increase proteomic diversity and to control gene expression either co- or post-transcriptionally. Alternative splicing occurs within a megadalton-sized, multi-component machine consisting of RNA and proteins; during the splicing process, this complex undergoes dynamic changes via RNA-RNA, protein-protein and RNA-protein interactions. Co-transcriptional splicing functionally integrates the transcriptional machinery, thereby enabling the two processes to influence one another, whereas post-transcriptional splicing facilitates the coupling of RNA splicing with post-splicing events. This review addresses the structural aspects of spliceosomes and the mechanistic implications of their stepwise assembly on the regulation of pre-mRNA splicing. Moreover, the role of phosphorylation-based, signal-induced changes in the regulation of the splicing process is demonstrated.
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20
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Expression and Clinical Role of Cdc5L as a Novel Cell Cycle Protein in Hepatocellular Carcinoma. Dig Dis Sci 2016; 61:795-805. [PMID: 26553251 DOI: 10.1007/s10620-015-3937-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 10/22/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND Cell division cycle 5-like (Cdc5L), as a pre-mRNA splicing factor, is a regulator of mitotic progression. Previous study found that deletion of endogenous Cdc5L decreases the cell viability via dramatic mitotic arrest, while the role of Cdc5L in cancer biology remains under debate. AIMS To investigate the involvement of Cdc5L in the progression of hepatocellular carcinoma (HCC). METHODS In this study, the expression of Cdc5L was evaluated by Western blot in 8 paired fresh HCC tissues and immunohistochemistry on 116 paraffin-embedded slices. We treated HCC cells by nocodazole to analyze the role of Cdc5L in mitotic progress. To determine whether Cdc5L could regulate the proliferation of HCC cells, we increased endogenous Cdc5L and analyzed the proliferation of HCC cells using Western blot, CCK8, flow cytometry assays, and colony formation analyses. Furthermore, Cdc5L-siRNA oligos were used to confirm that Cdc5L plays an essential role in HCC development. RESULTS Cdc5L was highly expressed in HCC and significantly associated with multiple clinicopathological factors, including AJCC stage, tumor size, and Ki-67. Besides, univariate and multivariate survival analyses demonstrated that high Cdc5L expression was an independent prognostic factor for HCC patients' poor survival. Overexpression of Cdc5L favors cell cycle progress of HCC cells, while downregulation of Cdc5L results in cell cycle arrest at G2/M phase and reduced cell proliferation of HCC cells. CONCLUSIONS Our findings suggested that Cdc5L could play an important role in the tumorigenesis of HCC and thus be a potential therapeutical target to prevent HCC progression.
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21
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Rebelo S, Santos M, Martins F, da Cruz e Silva EF, da Cruz e Silva OA. Protein phosphatase 1 is a key player in nuclear events. Cell Signal 2015; 27:2589-98. [DOI: 10.1016/j.cellsig.2015.08.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/31/2015] [Accepted: 08/10/2015] [Indexed: 12/17/2022]
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22
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Winkler C, De Munter S, Van Dessel N, Lesage B, Heroes E, Boens S, Beullens M, Van Eynde A, Bollen M. The selective inhibition of protein phosphatase-1 results in mitotic catastrophe and impaired tumor growth. J Cell Sci 2015; 128:4526-37. [PMID: 26542020 DOI: 10.1242/jcs.175588] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 10/26/2015] [Indexed: 01/07/2023] Open
Abstract
The serine/threonine protein phosphatase-1 (PP1) complex is a key regulator of the cell cycle. However, the redundancy of PP1 isoforms and the lack of specific inhibitors have hampered studies on the global role of PP1 in cell cycle progression in vertebrates. Here, we show that the overexpression of nuclear inhibitor of PP1 (NIPP1; also known as PPP1R8) in HeLa cells culminated in a prometaphase arrest, associated with severe spindle-formation and chromosome-congression defects. In addition, the spindle assembly checkpoint was activated and checkpoint silencing was hampered. Eventually, most cells either died by apoptosis or formed binucleated cells. The NIPP1-induced mitotic arrest could be explained by the inhibition of PP1 that was titrated away from other mitotic PP1 interactors. Consistent with this notion, the mitotic-arrest phenotype could be rescued by the overexpression of PP1 or the inhibition of the Aurora B kinase, which acts antagonistically to PP1. Finally, we demonstrate that the overexpression of NIPP1 also hampered colony formation and tumor growth in xenograft assays in a PP1-dependent manner. Our data show that the selective inhibition of PP1 can be used to induce cancer cell death through mitotic catastrophe.
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Affiliation(s)
- Claudia Winkler
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Sofie De Munter
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Nele Van Dessel
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Bart Lesage
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Ewald Heroes
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Shannah Boens
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Monique Beullens
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, Leuven B-3000, Belgium
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23
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Ahn JW, Sik Jin K, Francis Son H, Ho Chang J, Kim KJ. Small angle X-ray scattering studies of CTNNBL1 dimerization and CTNNBL1/CDC5L complex. Sci Rep 2015; 5:14251. [PMID: 26381213 PMCID: PMC4585563 DOI: 10.1038/srep14251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/21/2015] [Indexed: 01/13/2023] Open
Abstract
The hPrp19/CDC5L complex is a non-snRNP spliceosome complex that plays a key role in the spliceosome activation during pre-mRNA splicing, and CTNNBL1 and CDC5L are essential components of the complex. In this study, to investigate the oligomeric state of CTNNBL1 in solution, we performed small angle X-ray scattering experiments in various concentrations of NaCl. We observed that CTNNBL1 existed as a dimer in physiological NaCl concentrations. Site-directed mutagenesis experiment of CTNNBL1 confirmed that N-terminal capping region and the first four ARM repeats are important for dimerization of the protein. We also found that the positively-charged NLS3-containing region (residues 197-235) of CDC5L bound to the negatively-charged patch of CTNNBL1 and that the CTNNBL1/CDC5L complex formed a heterotetramer consisting of one CTNNBL1 dimer and one CDC5L dimer. Moreover, reconstruction of 3D models of CTNNBL1/CDC5L complexes containing CTNNBL1 and three different truncated forms of CDC5L showed that the CDC5L(141-196) region and the CDC5L(236-377) region were positioned at the top of the N-terminal capping region and at the bottom of ARM VII of CTNNBL1, respectively.
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Affiliation(s)
- Jae-Woo Ahn
- School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Korea
| | - Kyeong Sik Jin
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Jigok-ro 80, Pohang, Kyungbuk 790-784, Korea
| | - Hyeoncheol Francis Son
- School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Korea
| | - Jeong Ho Chang
- Department of Biology, Teachers College, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Korea
| | - Kyung-Jin Kim
- School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Korea
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24
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Chou MH, Hsieh YC, Huang CW, Chen PH, Chan SP, Tsao YP, Lee HH, Wu JT, Chen SL. BCAS2 Regulates Delta-Notch Signaling Activity through Delta Pre-mRNA Splicing in Drosophila Wing Development. PLoS One 2015; 10:e0130706. [PMID: 26091239 PMCID: PMC4475048 DOI: 10.1371/journal.pone.0130706] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 05/23/2015] [Indexed: 11/19/2022] Open
Abstract
Previously, we showed that BCAS2 is essential for Drosophila viability and functions in pre-mRNA splicing. In this study, we provide strong evidence that BCAS2 regulates the activity of Delta-Notch signaling via Delta pre-mRNA splicing. Depletion of dBCAS2 reduces Delta mRNA expression and leads to accumulation of Delta pre-mRNA, resulting in diminished transcriptions of Delta-Notch signaling target genes, such as cut and E(spl)m8. Furthermore, ectopic expression of human BCAS2 (hBCAS2) and Drosophila BCAS2 (dBCAS2) in a dBCAS2-deprived fly can rescue dBCAS2 depletion-induced wing damage to the normal phenotypes. These rescued phenotypes are correlated with the restoration of Delta pre-mRNA splicing, which affects Delta-Notch signaling activity. Additionally, overexpression of Delta can rescue the wing deformation by deprivation of dBCAS2; and the depletion of dBCAS2 can restore the aberrant eye associated with Delta-overexpressing retinas; providing supporting evidence for the regulation of Delta-Notch signaling by dBCAS2. Taken together, dBCAS2 participates in Delta pre-mRNA splicing that affects the regulation of Delta-Notch signaling in Drosophila wing development.
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Affiliation(s)
- Meng-Hsuan Chou
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, 100, Taiwan
| | - Yi-Chen Hsieh
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, 100, Taiwan
| | - Chu-Wei Huang
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, 100, Taiwan
| | - Po-Han Chen
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, 100, Taiwan
| | - Shih-Peng Chan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, 100, Taiwan
| | - Yeou-Ping Tsao
- Department of Ophthalmology, Mackay Memorial Hospital, Taipei, 104, Taiwan
| | - Hsiu-Hsiang Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, 100, Taiwan
| | - June-Tai Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, 100, Taiwan
- Department of Medical Research, National Taiwan University Hospital, Taipei, 100, Taiwan
- * E-mail: (SLC); (JTW)
| | - Show-Li Chen
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, 100, Taiwan
- * E-mail: (SLC); (JTW)
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25
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Protein phosphatase PP1-NIPP1 activates mesenchymal genes in HeLa cells. FEBS Lett 2015; 589:1314-21. [DOI: 10.1016/j.febslet.2015.04.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/07/2015] [Accepted: 04/12/2015] [Indexed: 11/22/2022]
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26
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Wu Z, Cheng Z, Sun M, Wan X, Liu P, He T, Tan M, Zhao Y. A chemical proteomics approach for global analysis of lysine monomethylome profiling. Mol Cell Proteomics 2014; 14:329-39. [PMID: 25505155 DOI: 10.1074/mcp.m114.044255] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Methylation of lysine residues on histone proteins is known to play an important role in chromatin structure and function. However, non-histone protein substrates of this modification remain largely unknown. An effective approach for system-wide analysis of protein lysine methylation, particularly lysine monomethylation, is lacking. Here we describe a chemical proteomics approach for global screening for monomethyllysine substrates, involving chemical propionylation of monomethylated lysine, affinity enrichment of the modified monomethylated peptides, and HPLC/MS/MS analysis. Using this approach, we identified with high confidence 446 lysine monomethylation sites in 398 proteins, including three previously unknown histone monomethylation marks, representing the largest data set of protein lysine monomethylation described to date. Our data not only confirms previously discovered lysine methylation substrates in the nucleus and spliceosome, but also reveals new substrates associated with diverse biological processes. This method hence offers a powerful approach for dynamic study of protein lysine monomethylation under diverse cellular conditions and in human diseases.
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Affiliation(s)
- Zhixiang Wu
- From the ‡The Chemical Proteomics Center and State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, P.R. China
| | - Zhongyi Cheng
- §Jingjie PTM BioLab (Hangzhou) Co. Ltd, Hangzhou, P.R. China
| | - Mingwei Sun
- From the ‡The Chemical Proteomics Center and State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, P.R. China
| | - Xuelian Wan
- From the ‡The Chemical Proteomics Center and State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, P.R. China
| | - Ping Liu
- From the ‡The Chemical Proteomics Center and State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, P.R. China
| | - Tieming He
- §Jingjie PTM BioLab (Hangzhou) Co. Ltd, Hangzhou, P.R. China
| | - Minjia Tan
- From the ‡The Chemical Proteomics Center and State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, P.R. China;
| | - Yingming Zhao
- From the ‡The Chemical Proteomics Center and State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, P.R. China; ¶Ben May Department of Cancer Research, The University of Chicago, Chicago, Illinois
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Meng Y, Guo Y, Qian Y, Guo X, Gao L, Sha J, Cui Y, Chian RC, Liu J. Effects of GnRH antagonist on endometrial protein profiles in the window of implantation. Proteomics 2014; 14:2350-9. [PMID: 25065715 DOI: 10.1002/pmic.201400145] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 06/24/2014] [Accepted: 07/23/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Yan Meng
- State key Laboratory of Reproductive Medicine; Clinical Center of Reproductive Medicine, the First Affiliated Hospital of Nanjing Medical University; Nanjing P. R. China
| | - Yueshuai Guo
- State Key Laboratory of Reproductive Medicine; Department of Histology and Embryology; Nanjing Medical University; Nanjing P. R. China
| | - Yi Qian
- State key Laboratory of Reproductive Medicine; Clinical Center of Reproductive Medicine, the First Affiliated Hospital of Nanjing Medical University; Nanjing P. R. China
| | - Xuejiang Guo
- State Key Laboratory of Reproductive Medicine; Department of Histology and Embryology; Nanjing Medical University; Nanjing P. R. China
| | - Li Gao
- State key Laboratory of Reproductive Medicine; Clinical Center of Reproductive Medicine, the First Affiliated Hospital of Nanjing Medical University; Nanjing P. R. China
| | - Jiahao Sha
- State Key Laboratory of Reproductive Medicine; Department of Histology and Embryology; Nanjing Medical University; Nanjing P. R. China
| | - Yugui Cui
- State key Laboratory of Reproductive Medicine; Clinical Center of Reproductive Medicine, the First Affiliated Hospital of Nanjing Medical University; Nanjing P. R. China
| | - Ri-Cheng Chian
- State key Laboratory of Reproductive Medicine; Clinical Center of Reproductive Medicine, the First Affiliated Hospital of Nanjing Medical University; Nanjing P. R. China
| | - Jiayin Liu
- State key Laboratory of Reproductive Medicine; Clinical Center of Reproductive Medicine, the First Affiliated Hospital of Nanjing Medical University; Nanjing P. R. China
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28
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Liebisch M, Bondeva T, Franke S, Daniel C, Amann K, Wolf G. Activation of the receptor for advanced glycation end products induces nuclear inhibitor of protein phosphatase-1 suppression. Kidney Int 2014; 86:103-17. [PMID: 24476693 DOI: 10.1038/ki.2014.3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/09/2013] [Accepted: 12/12/2013] [Indexed: 01/05/2023]
Abstract
The activation of the receptor for advanced glycation end products (RAGE) is involved in the development of diabetic nephropathy. Analysis of protein phosphatase-1 indicated that advanced glycation end products did not affect its expression, but increased its phosphatase activity. Using differential display analysis we previously demonstrated that stimulation of RAGE in podocytes modulates the expression of numerous genes, among others nuclear inhibitor of protein phosphatase-1 (NIPP1). Here we found that silencing of NIPP1 induced podocyte hypertrophy, cell cycle arrest, and significantly increased protein phosphatase-1 activity. NIPP1 downregulation was associated with increased p27(Kip1) protein expression. Reporter assays revealed a transcriptional activation of nuclear factor-κB in podocytes after suppression of NIPP1. The protein level of NIPP1 was also significantly reduced in podocytes of diabetic mice. Blocking the RAGE in vivo by a soluble analog elevated the NIPP1 protein in podocytes of diabetic mice. Thus, activation of the RAGE by advanced glycation end products or other ligands suppresses NIPP1 expression in diabetic nephropathy, contributes to podocyte hypertrophy, and glomerular inflammation.
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Affiliation(s)
- Marita Liebisch
- Department of Internal Medicine III, University Hospital Jena, Jena, Germany
| | - Tzvetanka Bondeva
- Department of Internal Medicine III, University Hospital Jena, Jena, Germany
| | - Sybille Franke
- Department of Internal Medicine III, University Hospital Jena, Jena, Germany
| | - Christoph Daniel
- Nephropathology Department, Institute of Pathology, Erlangen-Nürnberg University, Erlangen, Germany
| | - Kerstin Amann
- Nephropathology Department, Institute of Pathology, Erlangen-Nürnberg University, Erlangen, Germany
| | - Gunter Wolf
- Department of Internal Medicine III, University Hospital Jena, Jena, Germany
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29
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Naro C, Sette C. Phosphorylation-mediated regulation of alternative splicing in cancer. Int J Cell Biol 2013; 2013:151839. [PMID: 24069033 PMCID: PMC3771450 DOI: 10.1155/2013/151839] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/26/2013] [Indexed: 12/12/2022] Open
Abstract
Alternative splicing (AS) is one of the key processes involved in the regulation of gene expression in eukaryotic cells. AS catalyzes the removal of intronic sequences and the joining of selected exons, thus ensuring the correct processing of the primary transcript into the mature mRNA. The combinatorial nature of AS allows a great expansion of the genome coding potential, as multiple splice-variants encoding for different proteins may arise from a single gene. Splicing is mediated by a large macromolecular complex, the spliceosome, whose activity needs a fine regulation exerted by cis-acting RNA sequence elements and trans-acting RNA binding proteins (RBP). The activity of both core spliceosomal components and accessory splicing factors is modulated by their reversible phosphorylation. The kinases and phosphatases involved in these posttranslational modifications significantly contribute to AS regulation and to its integration in the complex regulative network that controls gene expression in eukaryotic cells. Herein, we will review the major canonical and noncanonical splicing factor kinases and phosphatases, focusing on those whose activity has been implicated in the aberrant splicing events that characterize neoplastic transformation.
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Affiliation(s)
- Chiara Naro
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
- Laboratories of Neuroembryology and of Cellular and Molecular Neurobiology, Fondazione Santa Lucia IRCCS, 00143 Rome, Italy
| | - Claudio Sette
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
- Laboratories of Neuroembryology and of Cellular and Molecular Neurobiology, Fondazione Santa Lucia IRCCS, 00143 Rome, Italy
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30
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Ghigna C, Riva S, Biamonti G. Alternative splicing of tumor suppressors and oncogenes. Cancer Treat Res 2013; 158:95-117. [PMID: 24222355 DOI: 10.1007/978-3-642-31659-3_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Alternative splicing is a fundamental mechanism to modulate gene expression programs in response to different growth and environmental stimuli. There is now ample evidence that alternative splicing errors, caused by mutations in cis-acting elements and defects and/or imbalances in trans-acting factors, may be causatively associated to cancer progression. Recent work indicates the existence of an intricate network of interactions between alternative splicing events and signal transduction pathways. In this network, splicing factors occupy a central position and appear to function both as targets and effectors of regulatory circuits. Thus, a change in their activity deeply affects alternative splicing profiles and hence the cell behavior. Here, we discuss a number of cases that exemplify the involvement of deregulated alternative splicing in tumor progression.
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Affiliation(s)
- Claudia Ghigna
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche, Pavia, 27100, Italy
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31
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Minnebo N, Görnemann J, O'Connell N, Van Dessel N, Derua R, Vermunt MW, Page R, Beullens M, Peti W, Van Eynde A, Bollen M. NIPP1 maintains EZH2 phosphorylation and promoter occupancy at proliferation-related target genes. Nucleic Acids Res 2012; 41:842-54. [PMID: 23241245 PMCID: PMC3553949 DOI: 10.1093/nar/gks1255] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The histone methyltransferase EZH2 regulates cell proliferation and differentiation by silencing Polycomb group target genes. NIPP1, a nuclear regulator of serine/threonine protein phosphatase 1 (PP1), has been implicated in the regulation of EZH2 occupancy at target loci, but the underlying mechanism is not understood. Here, we demonstrate that the phosphorylation of EZH2 by cyclin-dependent kinases at Thr416 creates a docking site for the ForkHead-associated domain of NIPP1. Recruited NIPP1 enables the net phosphorylation of EZH2 by inhibiting its dephosphorylation by PP1. Accordingly, a NIPP1-binding mutant of EZH2 is hypophosphorylated, and the knockdown of NIPP1 results in a reduced phosphorylation of endogenous EZH2. Conversely, the loss of PP1 is associated with a hyperphosphorylation of EZH2. A genome-wide promoter-binding profiling in HeLa cells revealed that the NIPP1-binding mutant shows a deficient association with about a third of the Polycomb target genes, and these are enriched for functions in proliferation. Our data identify PP1 as an EZH2 phosphatase and demonstrate that the phosphorylation-regulated association of EZH2 with proliferation-related targets depends on associated NIPP1.
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Affiliation(s)
- Nikki Minnebo
- Laboratory of Biosignaling & Therapeutics, Department of Cellular and Molecular Medicine, KU Leuven, B-3000 Leuven, Belgium
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32
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Multiple cis-elements and trans-acting factors regulate dynamic spatio-temporal transcription of let-7 in Caenorhabditis elegans. Dev Biol 2012. [PMID: 23201578 DOI: 10.1016/j.ydbio.2012.11.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The let-7 microRNA (miRNA) is highly conserved across animal phyla and generally regulates cellular differentiation and developmental timing pathways. In Caenorhabditis elegans, the mature let-7 miRNA starts to accumulate in the last stages of larval development where it directs cellular differentiation programs required for adult fates. Here, we show that expression of the let-7 gene in C. elegans is under complex transcriptional control. The onset of let-7 transcription begins as early as the first larval stage in some tissues, and as late as the third larval stage in others, and is abrogated at the gravid adult stage. Transcription from two different start sites in the let-7 promoter oscillates during each larval stage. We show that transcription is regulated by two distinct cis-elements in the promoter of let-7, the previously described temporal regulatory element (TRE), and a novel element downstream of the TRE that we have named the let-7 transcription element (LTE). These elements play distinct and redundant roles in regulating let-7 expression in specific tissues. In the absence of the TRE and LTE, transcription of let-7 is undetectable and worms exhibit the lethal phenotype characteristic of let-7 null mutants. We also identify several genes that affect the transcription of let-7 generally and tissue-specifically. Overall, spatio-temporal regulation of let-7 transcription is orchestrated by multiple cis- and trans-acting factors to ensure appropriate expression of this essential miRNA during worm development.
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33
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O'Connell N, Nichols SR, Heroes E, Beullens M, Bollen M, Peti W, Page R. The molecular basis for substrate specificity of the nuclear NIPP1:PP1 holoenzyme. Structure 2012; 20:1746-56. [PMID: 22940584 PMCID: PMC3472097 DOI: 10.1016/j.str.2012.08.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 08/06/2012] [Accepted: 08/07/2012] [Indexed: 11/18/2022]
Abstract
Regulation of protein phosphatase 1 (PP1) is controlled by a diverse array of regulatory proteins. However, how these proteins direct PP1 specificity is not well understood. More than one-third of the nuclear pool of PP1 forms a holoenzyme with the nuclear inhibitor of PP1, NIPP1, to regulate chromatin remodeling, among other essential biological functions. Here, we show that the PP1-binding domain of NIPP1 is an intrinsically disordered protein, which binds PP1 in an unexpected manner. NIPP1 forms an α helix that engages PP1 at a unique interaction site, using polar rather than hydrophobic contacts. Importantly, the structure also reveals a shared PP1 interaction site outside of the RVxF motif, the ΦΦ motif. Finally, we show that NIPP1:PP1 substrate selectivity is determined by altered electrostatics and enhanced substrate localization. Together, our results provide the molecular basis by which NIPP1 directs PP1 substrate specificity in the nucleus.
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Affiliation(s)
- Nichole O'Connell
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912, USA
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34
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Hutten S, Prescott A, James J, Riesenberg S, Boulon S, Lam YW, Lamond AI. An intranucleolar body associated with rDNA. Chromosoma 2011; 120:481-99. [PMID: 21698343 PMCID: PMC3232531 DOI: 10.1007/s00412-011-0327-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 05/16/2011] [Accepted: 05/31/2011] [Indexed: 02/07/2023]
Abstract
The nucleolus is the subnuclear organelle responsible for ribosome subunit biogenesis and can also act as a stress sensor. It forms around clusters of ribosomal DNA (rDNA) and is mainly organised in three subcompartments, i.e. fibrillar centre, dense fibrillar component and granular component. Here, we describe the localisation of 21 protein factors to an intranucleolar region different to these main subcompartments, called the intranucleolar body (INB). These factors include proteins involved in DNA maintenance, protein turnover, RNA metabolism, chromatin organisation and the post-translational modifiers SUMO1 and SUMO2/3. Increase in the size and number of INBs is promoted by specific types of DNA damage and depends on the functional integrity of the nucleolus. INBs are abundant in nucleoli of unstressed cells during S phase and localise in close proximity to rDNA with heterochromatic features. The data suggest the INB is linked with regulation of rDNA transcription and/or maintenance of rDNA.
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Affiliation(s)
- Saskia Hutten
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, UK
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35
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Kuehnen P, Laubner K, Raile K, Schöfl C, Jakob F, Pilz I, Päth G, Seufert J. Protein phosphatase 1 (PP-1)-dependent inhibition of insulin secretion by leptin in INS-1 pancreatic β-cells and human pancreatic islets. Endocrinology 2011; 152:1800-8. [PMID: 21427225 DOI: 10.1210/en.2010-1094] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Leptin inhibits insulin secretion from pancreatic β-cells, and in turn, insulin stimulates leptin biosynthesis and secretion from adipose tissue. Dysfunction of this adipoinsular feedback loop has been proposed to be involved in the development of hyperinsulinemia and type 2 diabetes mellitus. At the molecular level, leptin acts through various pathways, which in combination confer inhibitory effects on insulin biosynthesis and secretion. The aim of this study was to identify molecular mechanisms of leptin action on insulin secretion in pancreatic β-cells. To identify novel leptin-regulated genes, we performed subtraction PCR in INS-1 β-cells. Regulated expression of identified genes was confirmed by RT-PCR and Northern and Western blotting. Furthermore, functional impact on β-cell function was characterized by insulin-secretion assays, intracellular Ca²(+) concentration measurements, and enzyme activity assays. PP-1α, the catalytic subunit of protein phosphatase 1 (PP-1), was identified as a novel gene down-regulated by leptin in INS-1 pancreatic β-cells. Expression of PP-1α was verified in human pancreatic sections. PP-1α mRNA and protein expression is down-regulated by leptin, which culminates in reduction of PP-1 enzyme activity in β-cells. In addition, glucose-induced insulin secretion was inhibited by nuclear inhibitor of PP-1 and calyculin A, which was in part mediated by a reduction of PP-1-dependent calcium influx into INS-1 β-cells. These results identify a novel molecular pathway by which leptin confers inhibitory action on insulin secretion, and impaired PP-1 inhibition by leptin may be involved in dysfunction of the adipoinsular axis during the development of hyperinsulinemia and type 2 diabetes mellitus.
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Affiliation(s)
- Peter Kuehnen
- Institute of Experimental Pediatric Endocrinology, Charité Children's Hospital, Universitätsmedizin Berlin, Berlin, Germany.
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36
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Van Dessel N, Beke L, Görnemann J, Minnebo N, Beullens M, Tanuma N, Shima H, Van Eynde A, Bollen M. The phosphatase interactor NIPP1 regulates the occupancy of the histone methyltransferase EZH2 at Polycomb targets. Nucleic Acids Res 2010; 38:7500-12. [PMID: 20671031 PMCID: PMC2995064 DOI: 10.1093/nar/gkq643] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Polycomb group (PcG) proteins are key regulators of stem-cell and cancer biology. They mainly act as repressors of differentiation and tumor-suppressor genes. One key silencing step involves the trimethylation of histone H3 on Lys27 (H3K27) by EZH2, a core component of the Polycomb Repressive Complex 2 (PRC2). The mechanism underlying the initial recruitment of mammalian PRC2 complexes is not well understood. Here, we show that NIPP1, a regulator of protein Ser/Thr phosphatase-1 (PP1), forms a complex with PP1 and PRC2 components on chromatin. The knockdown of NIPP1 or PP1 reduced the association of EZH2 with a subset of its target genes, whereas the overexpression of NIPP1 resulted in a retargeting of EZH2 from fully repressed to partially active PcG targets. However, the expression of a PP1-binding mutant of NIPP1 (NIPP1m) did not cause a redistribution of EZH2. Moreover, mapping of the chromatin binding sites with the DamID technique revealed that NIPP1 was associated with multiple PcG target genes, including the Homeobox A cluster, whereas NIPP1m showed a deficient binding at these loci. We propose that NIPP1 associates with a subset of PcG targets in a PP1-dependent manner and thereby contributes to the recruitment of the PRC2 complex.
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Affiliation(s)
- Nele Van Dessel
- Laboratory of Biosignaling and Therapeutics, Department of Molecular Cell Biology, Faculty of Medicine, KULeuven, B-3000 Leuven, Belgium
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37
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Zhang N, Kaur R, Akhter S, Legerski RJ. Cdc5L interacts with ATR and is required for the S-phase cell-cycle checkpoint. EMBO Rep 2009; 10:1029-35. [PMID: 19633697 DOI: 10.1038/embor.2009.122] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 04/22/2009] [Accepted: 04/23/2009] [Indexed: 11/09/2022] Open
Abstract
Cell division cycle 5-like protein (Cdc5L) is a core component of the putative E3 ubiquitin ligase complex containing Prp19/Pso4, Plrg1 and Spf27. This complex has been shown to have a role in pre-messenger RNA splicing from yeast to humans; however, more recent studies have described a function for this complex in the cellular response to DNA damage. Here, we show that Cdc5L interacts physically with the cell-cycle checkpoint kinase ataxia-telangiectasia and Rad3-related (ATR). Depletion of Cdc5L by RNA-mediated interference methods results in a defective S-phase cell-cycle checkpoint and cellular sensitivity in response to replication-fork blocking agents. Furthermore, we show that Cdc5L is required for the activation of downstream effectors or mediators of ATR checkpoint function such as checkpoint kinase 1 (Chk1), cell cycle checkpoint protein Rad 17 (Rad17) and Fanconi anaemia complementation group D2 protein (FancD2). In addition, we have mapped the ATR-binding region in Cdc5L and show that a deletion mutant that is unable to interact with ATR is defective in the rescue of the checkpoint deficiency in Cdc5L-depleted cells. These findings show a new function for Cdc5L in the regulation of the ATR-mediated cell-cycle checkpoint in response to genotoxic agents.
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Affiliation(s)
- Nianxiang Zhang
- Department of Genetics, The University of Texas MD Anderson Cancer Center, University of Texas, 1515 Holcombe Boulevard, Houston, Texas 77030, USA
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38
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Chen S, Kesler CT, Paschal BM, Balk SP. Androgen receptor phosphorylation and activity are regulated by an association with protein phosphatase 1. J Biol Chem 2009; 284:25576-84. [PMID: 19622840 DOI: 10.1074/jbc.m109.043133] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Androgen receptor (AR) is phosphorylated at multiple sites in response to ligand binding, but the functional consequences and mechanisms regulating AR phosphorylation remain to be established. We observed initially that okadaic acid, an inhibitor of the major PPP family serine/threonine phosphatases PP2A and protein phosphatase 1 (PP1), had cell type-dependent effects on AR expression. More specific inhibitors of PP2A (fostriecin) and PP1 (tautomycin and siRNA against the PP1alpha catalytic subunit) demonstrated that PP1 and protein phosphatase 2A had opposite effects on AR protein and transcriptional activity. PP1 inhibition enhanced proteasome-mediated AR degradation, while PP1alpha overexpression increased AR expression and markedly enhanced AR transcriptional activity. Coprecipitation experiments demonstrated an AR-PP1 interaction, while immunofluorescence and nuclear-cytoplasmic fractionation showed androgen-stimulated nuclear translocation of both AR and PP1 in prostate cancer cells. Studies with phosphospecific AR antibodies showed that PP1 inhibition dramatically increased phosphorylation of Ser-650, a site in the AR hinge region shown to mediate nuclear export. Significantly, PP1 inhibition caused a marked decrease in nuclear localization of the wild-type AR, but did not alter total or nuclear levels of a S650A mutant AR. These findings reveal a critical role of PP1 in regulating AR protein stability and nuclear localization through dephosphorylation of Ser-650. Moreover, AR may function as a PP1 regulatory subunit and mediate PP1 recruitment to chromatin, where it can modulate transcription and splicing.
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Affiliation(s)
- Shaoyong Chen
- Cancer Biology Program, Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
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Rogne M, Stokka AJ, Taskén K, Collas P, Küntziger T. Mutually exclusive binding of PP1 and RNA to AKAP149 affects the mitochondrial network. Hum Mol Genet 2008; 18:978-87. [PMID: 19074462 DOI: 10.1093/hmg/ddn425] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A-kinase-anchoring protein 149 (AKAP149) is a membrane protein of the mitochondrial and endoplasmic reticulum/nuclear envelope network. AKAP149 controls the subcellular localization and temporal order of protein phosphorylation by tethering protein kinases and phosphatases to these compartments. AKAP149 also includes an RNA-binding K homology (KH) domain, the loss of function of which has been associated in other proteins with neurodegenerative syndromes. We show here that protein phosphatase 1 (PP1) binding occurs through a conserved RVXF motif found in the KH domain of AKAP149 and that PP1 and RNA binding to this same site is mutually exclusive and controlled through a novel, phosphorylation-dependent mechanism. A collapse of the mitochondrial network is observed upon introduction of RNA-binding deficient mutants of AKAP149, pointing to the importance of RNA tethering to the mitochondrial membrane by AKAP149 for mitochondrial distribution.
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Affiliation(s)
- Marie Rogne
- 1Institute of Basic Medical Sciences, Department of Biochemistry, University of Oslo, Post Box 1112, Blindern, 0317 Oslo, Norway
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40
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Trowitzsch S, Weber G, Lührmann R, Wahl MC. Crystal structure of the Pml1p subunit of the yeast precursor mRNA retention and splicing complex. J Mol Biol 2008; 385:531-41. [PMID: 19010333 DOI: 10.1016/j.jmb.2008.10.087] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 10/21/2008] [Indexed: 10/21/2022]
Abstract
The precursor mRNA retention and splicing (RES) complex mediates nuclear retention and enhances splicing of precursor mRNAs. The RES complex from yeast comprises three proteins, Snu17p, Bud13p and Pml1p. Snu17p acts as a central platform that concomitantly binds the Bud13p and Pml1p subunits via short peptide epitopes. As a step to decipher the molecular architecture of the RES complex, we have determined crystal structures of full-length Pml1p and N-terminally truncated Pml1p. The first 50 residues of full-length Pml1p, encompassing the Snu17p-binding region, are disordered, showing that Pml1p binds to Snu17p via an intrinsically unstructured region. The remainder of Pml1p folds as a forkhead-associated (FHA) domain, which is expanded by a number of noncanonical elements compared with known FHA domains from other proteins. An atypical N-terminal appendix runs across one beta-sheet and thereby stabilizes the domain as shown by deletion experiments. FHA domains are thought to constitute phosphopeptide-binding elements. Consistently, a sulfate ion was found at the putative phosphopeptide-binding loops of full-length Pml1p. The N-terminally truncated version of the protein lacked a similar phosphopeptide mimic but retained an almost identical structure. A long loop neighboring the putative phosphopeptide-binding site was disordered in both structures. Comparison with other FHA domain proteins suggests that this loop adopts a defined conformation upon ligand binding and thereby confers ligand specificity. Our results show that in the RES complex, an FHA domain of Pml1p is flexibly tethered via an unstructured N-terminal region to Snu17p.
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Affiliation(s)
- Simon Trowitzsch
- Zelluläre Biochemie, Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, D-37077 Göttingen, Germany
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41
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Tanuma N, Kim SE, Beullens M, Tsubaki Y, Mitsuhashi S, Nomura M, Kawamura T, Isono K, Koseki H, Sato M, Bollen M, Kikuchi K, Shima H. Nuclear inhibitor of protein phosphatase-1 (NIPP1) directs protein phosphatase-1 (PP1) to dephosphorylate the U2 small nuclear ribonucleoprotein particle (snRNP) component, spliceosome-associated protein 155 (Sap155). J Biol Chem 2008; 283:35805-14. [PMID: 18842582 DOI: 10.1074/jbc.m805468200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pre-mRNA splicing entails reversible phosphorylation of spliceosomal proteins. Recent work has revealed essential roles for Ser/Thr phosphatases, such as protein phosphatase-1 (PP1), in splicing, but how these phosphatases are regulated is largely unknown. We show that nuclear inhibitor of PP1 (NIPP1), a major PP1 interactor in the vertebrate nucleus, recruits PP1 to Sap155 (spliceosome-associated protein 155), an essential component of U2 small nuclear ribonucleoprotein particles, and promotes Sap155 dephosphorylation. C-terminally truncated NIPP1 (NIPP1-DeltaC) formed a hyper-active holoenzyme with PP1, rendering PP1 minimally phosphorylated on an inhibitory site. Forced expression of NIPP1-WT and -DeltaC resulted in slight and severe decreases in Sap155 hyperphosphorylation, respectively, and the latter was accompanied with inhibition of splicing. PP1 overexpression produced similar effects, whereas small interfering RNA-mediated NIPP1 knockdown enhanced Sap155 hyperphosphorylation upon okadaic acid treatment. NIPP1 did not inhibit but rather stimulated Sap155 dephosphorylation by PP1 in vitro through facilitating Sap155/PP1 interaction. Further analysis revealed that NIPP1 specifically recognizes hyperphosphorylated Sap155 thorough its Forkhead-associated domain and dissociates from Sap155 after dephosphorylation by associated PP1. Thus NIPP1 works as a molecular sensor for PP1 to recognize phosphorylated Sap155.
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Affiliation(s)
- Nobuhiro Tanuma
- Division of Cancer Chemotherapy, Miyagi Cancer Center Research Institute, Natori 981-1293, Japan.
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42
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Xie J. Control of alternative pre-mRNA splicing by Ca(++) signals. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1779:438-52. [PMID: 18258215 PMCID: PMC3500379 DOI: 10.1016/j.bbagrm.2008.01.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 12/18/2007] [Accepted: 01/08/2008] [Indexed: 02/06/2023]
Abstract
Alternative pre-mRNA splicing is a common way of gene expression regulation in metazoans. The selective use of specific exons can be modulated in response to various manipulations that alter Ca(++) signals, particularly in neurons. A number of splicing factors have also been found to be controlled by Ca(++) signals. Moreover, pre-mRNA elements have been identified that are essential and sufficient to mediate Ca(++)-regulated splicing, providing model systems for dissecting the involved molecular components. In neurons, this regulation likely contributes to the fine-tuning of neuronal properties.
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Affiliation(s)
- Jiuyong Xie
- Department of Physiology, Faculty of Medicine, University of Manitoba, 730 William Avenue, Winnipeg, Canada MB R3E 3J7.
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43
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Gräub R, Lancero H, Pedersen A, Chu M, Padmanabhan K, Xu XQ, Spitz P, Chalkley R, Burlingame AL, Stokoe D, Bernstein HS. Cell cycle-dependent phosphorylation of human CDC5 regulates RNA processing. Cell Cycle 2008; 7:1795-803. [PMID: 18583928 DOI: 10.4161/cc.7.12.6017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
CDC5 proteins are components of the pre-mRNA splicing complex and essential for cell cycle progression in yeast, plants and mammals. Human CDC5 is phosphorylated in a mitogen-dependent manner, and its association with the spliceosome is ATP-dependent. Examination of the amino acid sequence suggests that CDC5L may be phosphorylated at up to 28 potential consensus recognition sequences for known kinases, however, the identity of actual phosphorylation sites, their role in regulating CDC5L activity, and the kinases responsible for their phosphorylation have not previously been determined. Using two-dimensional phosphopeptide mapping and nanoelectrospray mass spectrometry, we now show that CDC5L is phosphorylated on at least nine sites in vivo. We demonstrate that while CDC5L is capable of forming homodimers in vitro and in vivo, neither homodimerization nor nuclear localization is dependent on phosphorylation at these sites. Using an in vitro splicing assay, we show that phosphorylation of CDC5L at threonines 411 and 438 within recognition sequences for CDKs are required for CDC5L-mediated pre-mRNA splicing. We also demonstrate that a specific inhibitor of CDK2, CVT-313, inhibits CDC5L phosphorylation in both in vitro kinase assays and in vivo radiolabeling experiments in cycling cells. These studies represent the first demonstration of a regulatory role for phosphorylation of CDC5L, and suggest that targeting these sites or the implicated kinases may provide novel strategies for treating disorders of unguarded cellular proliferation, such as cancer.
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Affiliation(s)
- Remo Gräub
- Cardiovascular Research Institute, University of California, San Francisco, CA 94143-0130, USA
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44
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Kumeta H, Ogura K, Adachi S, Fujioka Y, Tanuma N, Kikuchi K, Inagaki F. The NMR structure of the NIPP1 FHA domain. JOURNAL OF BIOMOLECULAR NMR 2008; 40:219-224. [PMID: 18253837 DOI: 10.1007/s10858-008-9222-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Accepted: 01/10/2008] [Indexed: 05/25/2023]
Affiliation(s)
- Hiroyuki Kumeta
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, 060-0812, Japan
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45
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Kocanova S, Buytaert E, Matroule JY, Piette J, Golab J, de Witte P, Agostinis P. Induction of heme-oxygenase 1 requires the p38MAPK and PI3K pathways and suppresses apoptotic cell death following hypericin-mediated photodynamic therapy. Apoptosis 2008; 12:731-41. [PMID: 17219054 DOI: 10.1007/s10495-006-0016-x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Photodynamic therapy (PDT) is an established anticancer modality utilizing the photogeneration of reactive oxygen species (ROS) to kill the cancer cells and hypericin is a promising photosensitizer for the treatment of bladder tumors. In this paper we characterize the signaling pathways and the mechanisms leading to the up-regulation of the antioxidant enzyme heme oxygenase (HO-1) in PDT treated cancer cells. We show that PDT engages the p38(MAPK) and PI3K signaling cascades for HO-1 induction. p38(MAPK) inhibitors or small interfering RNA (siRNA) for p38(MAPK) suppress HO-1 induction after PDT and complete repression is attained when p38 and PI3K antagonists are combined. Blocking these signaling pathways increases additively the propensity of the cells to undergo PDT-induced apoptosis, mirroring the effect of HO-1 silencing. Conversely, increasing HO-1 protein level by hemin prior to irradiation is cytoprotective. HO-1 stimulation by PDT is dependent on transcription and de novo protein synthesis and it is preceded by the nuclear accumulation of the Nrf2 transcription factor, which is reduced by inhibitors of p38(MAPK) and PI3K. Altogether these results indicate that stimulation of HO-1 expression by hypericin-PDT is a cytoprotective mechanism governed by the p38(MAPK) and PI3K pathways, likely through the control of the nuclear availability of the Nrf2 pool.
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Affiliation(s)
- Silvia Kocanova
- Department Molecular and Cell Biology, Division of Biochemistry, Catholic University of Leuven, Campus Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium
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46
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Nuytten M, Beke L, Van Eynde A, Ceulemans H, Beullens M, Van Hummelen P, Fuks F, Bollen M. The transcriptional repressor NIPP1 is an essential player in EZH2-mediated gene silencing. Oncogene 2007; 27:1449-60. [PMID: 17724462 DOI: 10.1038/sj.onc.1210774] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
EZH2 is a Polycomb group (PcG) protein that promotes the late-stage development of cancer by silencing a specific set of genes, at least in part through trimethylation of associated histone H3 on Lys 27 (H3K27). Nuclear inhibitor of protein phosphatase-1 (NIPP1) is a ubiquitously expressed transcriptional repressor that has binding sites for the EZH2 interactor EED. Here, we examine the contribution of NIPP1 to EZH2-mediated gene silencing. Studies on NIPP1-deficient cells disclose a widespread and essential role of NIPP1 in the trimethylation of H3K27 by EZH2, not only in the onset of this trimethylation during embryonic development, but also in the maintenance of this repressive mark in proliferating cells. Consistent with this notion, EZH2 and NIPP1 silence a common set of genes, as revealed by gene-expression profiling, and NIPP1 is associated with established Polycomb target genes and with genomic regions that are enriched in Polycomb targets. Furthermore, most NIPP1 target genes are trimethylated on H3K27 and the knockdown of either NIPP1 or EZH2 is often associated with a loss of this modification. Our data reveal that NIPP1 is required for the global trimethylation of H3K27 and is implicated in gene silencing by EZH2.
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Affiliation(s)
- M Nuytten
- Laboratory of Biosignaling & Therapeutics, Department of Molecular Cell Biology, Faculty of Medicine, KULeuven, Leuven, Belgium
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47
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Ulke-Lemée A, Trinkle-Mulcahy L, Chaulk S, Bernstein NK, Morrice N, Glover M, Lamond AI, Moorhead GBG. The nuclear PP1 interacting protein ZAP3 (ZAP) is a putative nucleoside kinase that complexes with SAM68, CIA, NF110/45, and HNRNP-G. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:1339-50. [PMID: 17890166 DOI: 10.1016/j.bbapap.2007.07.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 07/13/2007] [Accepted: 07/26/2007] [Indexed: 01/21/2023]
Abstract
The targeting of protein kinases and phosphatases is fundamental to their roles as cellular regulators. The type one serine/threonine protein phosphatase (PP1) is enriched in the nucleus, yet few nuclear PP1 targeting subunits have been described and characterized. Here we show that the human protein, ZAP3 (also known as ZAP), is localized to the nucleus, that it is expressed in all mammalian tissues examined, and docks to PP1 through an RVRW motif located in its highly conserved carboxy-terminus. Proteomic analysis of a ZAP3 complex revealed that in addition to binding PP1, ZAP3 complexes with CIA (or nuclear receptor co-activator 5) and the RNA binding proteins hnRNP-G, SAM68 and NF110/45, but loses affinity for SAM68 and hnRNP-G upon digestion of endogenous nucleic acid. Bioinformatics has revealed that the conserved carboxy-terminus is orthologous to T4- and mammalian polynucleotide kinases with residues necessary for kinase activity maintained throughout evolution. Furthermore, the substrate binding pocket of uridine-cytidine kinase (or uridine kinase) has localized sequence similarity with ZAP3, suggesting uridine or cytidine as possible ZAP3 substrates. Most polynucleotide kinases have a phosphohydrolase domain in conjunction with their kinase domain. In ZAP3, although this domain is present, it now appears degenerate and functions to bind PP1 through an RVRW docking site located within the domain.
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Affiliation(s)
- Annegret Ulke-Lemée
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada
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48
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Blaustein M, Pelisch F, Srebrow A. Signals, pathways and splicing regulation. Int J Biochem Cell Biol 2007; 39:2031-48. [PMID: 17507279 DOI: 10.1016/j.biocel.2007.04.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Revised: 04/02/2007] [Accepted: 04/03/2007] [Indexed: 01/09/2023]
Abstract
Alternative splicing of messenger RNA precursors is an extraordinary source of protein diversity and the regulation of this process is crucial for diverse cellular functions in both physiological and pathological situations. For many years, several signaling pathways have been implicated in alternative splicing regulation. Recent work has begun to unravel the molecular mechanisms by which extracellular stimuli activate signaling cascades that modulate the activity of the splicing machinery and therefore the splicing pattern of many different target messenger RNA precursors. These experiments are revealing unexpected aspects of the mechanism that control splicing and the consequences of the regulated splicing events. We summarize here the current knowledge about signal-induced alternative splicing regulation of Slo, NR1, CD44, CD45 and fibronectin genes, and also discuss the importance of some of these events in determination of cellular fate. Furthermore, we highlight the relevance of signal-induced changes in phosphorylation state and subcellular distribution of splicing factors as a way of regulating the splicing process. Lastly, we explore new and unexpected findings about regulated splicing in anucleated cells.
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Affiliation(s)
- Matias Blaustein
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, IFIBYNE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Argentina
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49
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Shi Y, Reddy B, Manley JL. PP1/PP2A phosphatases are required for the second step of Pre-mRNA splicing and target specific snRNP proteins. Mol Cell 2006; 23:819-29. [PMID: 16973434 DOI: 10.1016/j.molcel.2006.07.022] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Revised: 06/05/2006] [Accepted: 07/26/2006] [Indexed: 11/22/2022]
Abstract
Pre-mRNA splicing is a complex and dynamic process in which protein phosphorylation and dephosphorylation both play important roles. Although specific phosphatases, such as PP1 and PP2A, have been implicated in splicing, direct evidence for their involvement has been lacking, and their exact function(s) in this process remain unknown. In this study, we show that PP1 and certain PP2A family phosphatases play essential but redundant roles in splicing. Unexpectedly, we found that these phosphatases are required principally for the second step of the splicing reaction. Furthermore, we provide evidence that components of U2 and U5 snRNPs, specifically SAP155 and U5-116 kDa, are the key spliceosomal substrates for these phosphatases. Based on these data, we propose that dephosphorylation of U2 and U5 snRNP components by PP1/PP2A family phosphatases facilitates essential structural rearrangements in the spliceosome during the transition from the first to the second step.
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Affiliation(s)
- Yongsheng Shi
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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50
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Morris ER, Chevalier D, Walker JC. DAWDLE, a forkhead-associated domain gene, regulates multiple aspects of plant development. PLANT PHYSIOLOGY 2006; 141:932-41. [PMID: 16679419 PMCID: PMC1489914 DOI: 10.1104/pp.106.076893] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Phosphoprotein-binding domains are found in many different proteins and specify protein-protein interactions critical for signal transduction pathways. Forkhead-associated (FHA) domains bind phosphothreonine and control many aspects of cell proliferation in yeast (Saccharomyces cerevisiae) and animal cells. The Arabidopsis (Arabidopsis thaliana) protein kinase-associated protein phosphatase includes a FHA domain that mediates interactions with receptor-like kinases, which in turn regulate a variety of signaling pathways involved in plant growth and pathogen responses. Screens for insertional mutations in other Arabidopsis FHA domain-containing genes identified a mutant with pleiotropic defects. dawdle (ddl) plants are developmentally delayed, produce defective roots, shoots, and flowers, and have reduced seed set. DDL is expressed in the root and shoot meristems and the reduced size of the root apical meristem in ddl plants suggests a role early in organ development.
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Affiliation(s)
- Erin R Morris
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211, USA
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