1
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Gupta S, Kumar M, Chaudhuri S, Kumar A. The non-canonical nuclear functions of key players of the PI3K-AKT-MTOR pathway. J Cell Physiol 2022; 237:3181-3204. [PMID: 35616326 DOI: 10.1002/jcp.30782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/05/2022] [Accepted: 05/02/2022] [Indexed: 12/29/2022]
Abstract
The PI3K-AKT-MTOR signal transduction pathway is one of the essential signalling cascades within the cell due to its involvement in many vital functions. The pathway initiates with the recruitment of phosphatidylinositol-3 kinases (PI3Ks) onto the plasma membrane, generating phosphatidylinositol-3,4,5-triphosphate [PtdIns(3,4,5)P3 ] and subsequently activating AKT. Being the central node of the PI3K network, AKT activates the mechanistic target of rapamycin kinase complex 1 (MTORC1) via Tuberous sclerosis complex 2 inhibition in the cytoplasm. Although the cytoplasmic role of the pathway has been widely explored for decades, we now know that most of the effector molecules of the PI3K axis diverge from the canonical route and translocate to other cell organelles including the nucleus. The presence of phosphoinositides (PtdIns) inside the nucleus itself indicates the existence of a nuclear PI3K signalling. The nuclear localization of these signaling components is evident in regulating many nuclear processes like DNA replication, transcription, DNA repair, maintenance of genomic integrity, chromatin architecture, and cell cycle control. Here, our review intends to present a comprehensive overview of the nuclear functions of the PI3K-AKT-MTOR signaling biomolecules.
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Affiliation(s)
- Sakshi Gupta
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, Karnataka, India
| | - Mukund Kumar
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, Karnataka, India
| | - Soumi Chaudhuri
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, Karnataka, India
| | - Arun Kumar
- Department of Molecular Reproduction, Development & Genetics, Indian Institute of Science, Bangalore, Karnataka, India
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2
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Mirzakhani K, Kallenbach J, Rasa SMM, Ribaudo F, Ungelenk M, Ehsani M, Gong W, Gassler N, Leeder M, Grimm MO, Neri F, Baniahmad A. The androgen receptor-lncRNASAT1-AKT-p15 axis mediates androgen-induced cellular senescence in prostate cancer cells. Oncogene 2022; 41:943-959. [PMID: 34667276 PMCID: PMC8837536 DOI: 10.1038/s41388-021-02060-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 09/02/2021] [Accepted: 10/04/2021] [Indexed: 11/09/2022]
Abstract
The bipolar androgen therapy (BAT) to treat prostate cancer (PCa) includes cycles of supraphysiological androgen levels (SAL) under androgen-deprivation therapy (ADT). We showed previously that SAL induces cellular senescence in androgen-sensitive PCa cells and in ex vivo-treated patient PCa tumor samples. Here, we analyzed the underlying molecular pathway and reveal that SAL induces cellular senescence in both, castration-sensitive (CSPC) LNCaP and castration-resistant PCa (CRPC) C4-2 cells through the cell cycle inhibitor p15INK4b and increased phosphorylation of AKT. Treatment with the AKT inhibitor (AKTi) potently inhibited SAL-induced expression of p15INK4b and cellular senescence in both cell lines. Proximity-ligation assays (PLA) combined with high-resolution laser-scanning microscopy indicate that SAL promotes interaction of endogenous androgen receptor (AR) with AKT in the cytoplasm as well as in the nucleus detectable after three days. Transcriptome sequencing (RNA-seq) comparing the SAL-induced transcriptomes of LNCaP with C4-2 cells as well as with AKTi-treated cell transcriptomes revealed landscapes for cell senescence. Interestingly, one of the identified genes is the lncRNASAT1. SAL treatment of native patient tumor samples ex vivo upregulates lncRNASAT1. In PCa tumor tissues, lncRNASAT1 is downregulated compared with nontumor tissues of the same patients. Knockdown indicates that the lncRNASAT1 is crucial for SAL-induced cancer-cell senescence as an upstream factor for pAKT and for p15INK4b. Further, knockdown of lncRNASAT1 enhances cell proliferation by SAL, suggesting that lncRNASAT1 serves as a tumor suppressor at SAL. Interestingly, immunoprecipitation of AR detected lncRNASAT1 as an AR-interacting partner that regulates AR target-gene expression. Similarly, RNA-ChIP experiments revealed the interaction of AR with lncRNASAT1 on chromatin. Thus, we identified a novel AR-lncRNASAT1-AKT-p15INK4b signaling axis to mediate SAL-induced cellular senescence.
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MESH Headings
- Humans
- Male
- Cellular Senescence/drug effects
- Cellular Senescence/genetics
- Receptors, Androgen/metabolism
- Receptors, Androgen/genetics
- Proto-Oncogene Proteins c-akt/metabolism
- Prostatic Neoplasms/pathology
- Prostatic Neoplasms/metabolism
- Prostatic Neoplasms/genetics
- Prostatic Neoplasms/drug therapy
- Cell Line, Tumor
- Androgens/pharmacology
- Androgens/metabolism
- RNA, Long Noncoding/genetics
- RNA, Long Noncoding/metabolism
- Gene Expression Regulation, Neoplastic/drug effects
- Signal Transduction/drug effects
- Prostatic Neoplasms, Castration-Resistant/pathology
- Prostatic Neoplasms, Castration-Resistant/metabolism
- Prostatic Neoplasms, Castration-Resistant/genetics
- Prostatic Neoplasms, Castration-Resistant/drug therapy
- Cell Proliferation/drug effects
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Affiliation(s)
- Kimia Mirzakhani
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | - Julia Kallenbach
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | | | - Federico Ribaudo
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | - Martin Ungelenk
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | - Marzieh Ehsani
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | - Wenrong Gong
- Medical College, Hubei University of Arts and Science, Xiangyang, China
- SCW Medicath LTD, Baolong industrial Town, Shenzhen, China
| | - Nikolaus Gassler
- Section of Pathology, Institute of Forensic Medicine, Jena University Hospital, Jena, Germany
| | - Mirjam Leeder
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | - Marc-Oliver Grimm
- Department of Adult and Pediatric Urology, Jena University Hospital, Jena, Germany
| | | | - Aria Baniahmad
- Institute of Human Genetics, Jena University Hospital, Jena, Germany.
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3
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Nandi N, Zaidi Z, Tracy C, Krämer H. A phospho-switch at Acinus-Serine 437 controls autophagic responses to Cadmium exposure and neurodegenerative stress. eLife 2022; 11:72169. [PMID: 35037620 PMCID: PMC8794470 DOI: 10.7554/elife.72169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 01/14/2022] [Indexed: 12/09/2022] Open
Abstract
Neuronal health depends on quality control functions of autophagy, but mechanisms regulating neuronal autophagy are poorly understood. Previously, we showed that in Drosophila starvation-independent quality control autophagy is regulated by acinus (acn) and the Cdk5-dependent phosphorylation of its serine437 (Nandi et al., 2017). Here, we identify the phosphatase that counterbalances this activity and provides for the dynamic nature of acinus-serine437 (acn-S437) phosphorylation. A genetic screen identified six phosphatases that genetically interacted with an acn gain-of-function model. Among these, loss of function of only one, the PPM-type phosphatase Nil (CG6036), enhanced pS437-acn levels. Cdk5-dependent phosphorylation of acn-S437 in nil1 animals elevates neuronal autophagy and reduces the accumulation of polyQ proteins in a Drosophila Huntington’s disease model. Consistent with previous findings that Cd2+ inhibits PPM-type phosphatases, Cd2+ exposure elevated acn-S437 phosphorylation which was necessary for increased neuronal autophagy and protection against Cd2+-induced cytotoxicity. Together, our data establish the acn-S437 phosphoswitch as critical integrator of multiple stress signals regulating neuronal autophagy.
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Affiliation(s)
- Nilay Nandi
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Zuhair Zaidi
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Charles Tracy
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Helmut Krämer
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
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4
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Chen M, Wu W, Liu D, Lv Y, Deng H, Gao S, Gu Y, Huang M, Guo X, Liu B, Zhao B, Pang Q. Evolution and Structure of API5 and Its Roles in Anti-Apoptosis. Protein Pept Lett 2021; 28:612-622. [PMID: 33319655 DOI: 10.2174/0929866527999201211195551] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 10/30/2020] [Accepted: 11/11/2020] [Indexed: 12/30/2022]
Abstract
Apoptosis, also named programmed cell death, is a highly conserved physiological mechanism. Apoptosis plays crucial roles in many life processes, such as tissue development, organ formation, homeostasis maintenance, resistance against external aggression, and immune responses. Apoptosis is regulated by many genes, among which Apoptosis Inhibitor-5 (API5) is an effective inhibitor, though the structure of API5 is completely different from the other known Inhibitors of Apoptosis Proteins (IAPs). Due to its high expression in many types of tumors, API5 has received extensive attention, and may be an effective target for cancer treatment. In order to comprehensively and systematically understand the biological roles of API5, we summarized the evolution and structure of API5 and its roles in anti-apoptosis in this review.
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Affiliation(s)
- Meishan Chen
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Weiwei Wu
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Dongwu Liu
- School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Yanhua Lv
- Department of Gynecology, Affiliated Hospital of Jining Medical University, Jining, Shandong 272000, China
| | - Hongkuan Deng
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Sijia Gao
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Yaqi Gu
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Mujie Huang
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Xiao Guo
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Baohua Liu
- Anti-Aging & Regenerative Medicine Research Institution, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Bosheng Zhao
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
| | - Qiuxiang Pang
- Laboratory of Developmental and Evolutionary Biology, School of Life Sciences, Shandong University of Technology, Zibo, Shandong 255049, China
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5
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Hu J, Xia X, Zhao Q, Li S. Lysine acetylation of NKG2D ligand Rae-1 stabilizes the protein and sensitizes tumor cells to NKG2D immune surveillance. Cancer Lett 2021; 502:143-153. [PMID: 33279621 PMCID: PMC10142196 DOI: 10.1016/j.canlet.2020.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 11/23/2020] [Accepted: 12/01/2020] [Indexed: 02/08/2023]
Abstract
Shedding, loss of expression, or internalization of natural killer group 2, member D (NKG2D) ligands from the tumor cell surface leads to immune evasion, which is associated with poor prognosis in patients with cancer. In many cancers, matrix metalloproteinases cause the proteolytic shedding of NKG2D ligands. However, it remained unclear how to protect NKG2D ligands from shedding. Here, we showed that the shedding of the mouse NKG2D ligand Rae-1 can be prevented by two critical acetyltransferases, GCN5 and PCAF, which acetylate the lysine residues of Rae-1 to avoid shedding both in vitro and in vivo. In contrast, mutations at lysines 80 and 87 of Rae-1 abrogated this acetylation and thereby desensitized tumor cells to NKG2D-dependent immune surveillance. Notably, the protein levels of GCN5 correlated with the expression levels of the human NKG2D ligand ULPB1 in a human tumor tissue microarray and, more importantly, with prolonged overall survival in many cancers. Our results suggest that the acetylation of Rae-1 protein at lysines 80 and 87 by GCN5 and PCAF protects Rae-1 from shedding so as to activate NKG2D-dependent immune surveillance. This discovery may shed light on new targets for NKG2D immunotherapy in cancer treatment.
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Affiliation(s)
- Jiemiao Hu
- Division of Pediatrics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 853, Houston, TX, 77030, USA
| | - Xueqing Xia
- Division of Pediatrics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 853, Houston, TX, 77030, USA
| | - Qingnan Zhao
- Division of Pediatrics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 853, Houston, TX, 77030, USA
| | - Shulin Li
- Division of Pediatrics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 853, Houston, TX, 77030, USA.
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6
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Shi H, Wang J, Liu F, Hu X, Lu Y, Yan S, Dai D, Yang X, Zhu Z, Guo Q. Proteome and phosphoproteome profiling reveals the regulation mechanism of hibernation in a freshwater leech (Whitmania pigra). J Proteomics 2020; 229:103866. [PMID: 32736137 DOI: 10.1016/j.jprot.2020.103866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 02/15/2020] [Accepted: 06/05/2020] [Indexed: 12/20/2022]
Abstract
Hibernation is an energy-saving and adaptive strategy adopted by leech, an important medicinal resource in Asia, to survive low temperature. Reversible protein phosphorylation (RPP) plays a key role in the regulation of mammalian hibernation processes but has never been documented in freshwater invertebrate such as leech. In this study, we detected the effects of hibernation on the proteome and phosphoproteome of the leech Whitmania pigra. A total of 2184 proteins and 2598 sites were quantified. Deep-hibernation resulted in 85 up-regulated and 107 down-regulated proteins and 318 up-regulated and 204 down-regulated phosphosites using a 1.5-fold threshold (P<0.05). Proteins involved in protein digestion and absorption, amino acid metabolism and N-glycan biosynthesis were significantly down-regulated during deep-hibernation. However, proteins involved in maintaining cell structure stability in hibernating animals were up-regulated. Differentially phosphorylated proteins provided the first global picture of a shift in energy metabolism, protein synthesis, cytoprotection and signaling during deep hibernation. Furthermore, AMP-activated protein kinase and protein kinase C play major roles in the regulation of these functional processes. These data significantly improve our understanding of the regulatory mechanisms of leech hibernation processes and provides substantial candidate phosphorylated proteins that could be important for functionally adapt in freshwater animals. SIGNIFICANCE: The leech Whitmania pigra as an important medicinal resource in Asia is an excellent model freshwater invertebrate for studies of environmentally-induced hibernation. The present study provides the first quantitative proteomics and phosphoproteomic analysis of leech hibernation using isobaric tag based TMT labeling and high-resolution mass spectrometry. These data significantly improve our understanding of the regulatory mechanisms when ectotherm animals face environmental stress and provides substantial candidate phosphorylated proteins that could be important for functionally adapt in freshwater animals.
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Affiliation(s)
- Hongzhuan Shi
- Institute of Chinese Medicinal Materials, Nanjing Agricultural University, Nanjing 210095, China
| | - Jia Wang
- Institute of Chinese Medicinal Materials, Nanjing Agricultural University, Nanjing 210095, China
| | - Fei Liu
- Institute of Chinese Medicinal Materials, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiangjing Hu
- Jingjie PTM Biolabs (Hangzhou) Co. Ltd, Hangzhou 310018, China
| | - Yiming Lu
- Jingjie PTM Biolabs (Hangzhou) Co. Ltd, Hangzhou 310018, China
| | - Shimeng Yan
- Institute of Chinese Medicinal Materials, Nanjing Agricultural University, Nanjing 210095, China
| | - Daoxin Dai
- Institute of Chinese Medicinal Materials, Nanjing Agricultural University, Nanjing 210095, China
| | - Xibin Yang
- Jingjie PTM Biolabs (Hangzhou) Co. Ltd, Hangzhou 310018, China
| | - Zaibiao Zhu
- Institute of Chinese Medicinal Materials, Nanjing Agricultural University, Nanjing 210095, China
| | - Qiaosheng Guo
- Institute of Chinese Medicinal Materials, Nanjing Agricultural University, Nanjing 210095, China.
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7
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Chen YS, Liu CW, Lin YC, Tsai CY, Yang CH, Lin JC. The SRSF3-MBNL1-Acin1 circuit constitutes an emerging axis to lessen DNA fragmentation in colorectal cancer via an alternative splicing mechanism. Neoplasia 2020; 22:702-713. [PMID: 33142236 PMCID: PMC7586066 DOI: 10.1016/j.neo.2020.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/30/2020] [Accepted: 10/04/2020] [Indexed: 02/07/2023] Open
Abstract
Altered alternative splicing (AS) events are considered pervasive causes that result in the development of carcinogenesis. Herein, we identified reprogrammed expression and splicing profiles of Muscle blind-like protein 1 (MBNL1) transcripts in tumorous tissues compared to those of adjacent normal tissues dissected from individual colorectal cancer (CRC) patients using whole-transcriptome analyses. MBNL1 transcript 8 (MBNL18) containing exons 5 and 7 was majorly generated by cancerous tissues and CRC-derived cell lines compared with those of the normal counterparts. Interplay between the exonic CA-rich element and upregulated SRSF3 facilitated the inclusion of MBNL1 exons 5 and 7, which encode a bipartite nuclear localization signal (NLS) and conformational NLS. Moreover, abundant SRSF3 interfered with the autoregulatory mechanism involved in utilization of MBNL1 exons 5 and 7, resulting in enrichment of the MBNL18 isoform in cultured CRC cell lines. Subsequently, an increase in the MBNL18 isoform drove a shift in the apoptotic chromatin condensation inducer in nucleus 1-S (Acin1-S) isoform to the Acin1-L isoform, leading to diminished DNA fragmentation in cultured CRC cells under oxidative stress. Taken together, SRSF3-MBNL1-Acin1 was demonstrated to constitute an emerging axis which is relevant to proapoptotic signatures and post-transcriptional events of CRC cells.
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Affiliation(s)
- Yi-Su Chen
- Department of Family Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Chao-Wei Liu
- Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Department of Laboratory Science, National Taiwan University Hospital, Taipei, Taiwan
| | - Ying-Chin Lin
- Department of Family Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Department of Family Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chia-Ying Tsai
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Ching-Hui Yang
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Jung-Chun Lin
- Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Pulmonary Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
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8
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Goméz-Mendoza DP, Lemos RP, Jesus ICG, Gorshkov V, McKinnie SMK, Vederas JC, Kjeldsen F, Guatimosim S, Santos RA, Pimenta AMC, Verano-Braga T. Moving Pieces in a Cellular Puzzle: A Cryptic Peptide from the Scorpion Toxin Ts14 Activates AKT and ERK Signaling and Decreases Cardiac Myocyte Contractility via Dephosphorylation of Phospholamban. J Proteome Res 2020; 19:3467-3477. [PMID: 32597192 DOI: 10.1021/acs.jproteome.0c00290] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cryptic peptides (cryptides) are biologically active peptides formed after proteolysis of native precursors present in animal venoms, for example. Proteolysis is an overlooked post-translational modification that increases venom complexity. The tripeptide KPP (Lys-Pro-Pro) is a peptide encrypted in the C-terminus of Ts14-a 25-mer peptide from the venom of the Tityus serrulatus scorpion that has a positive impact on the cardiovascular system, inducing vasodilation and reducing arterial blood pressure of hypertensive rats among other beneficial effects. A previous study reported that KPP and its native peptide Ts14 act via activation of the bradykinin receptor B2 (B2R). However, the cellular events underlying the activation of B2R by KPP are unknown. To study the cell signaling triggered by the Ts14 cryptide KPP, we incubated cardiac myocytes isolated from C57BL/6 mice with KPP (10-7 mol·L-1) for 0, 5, or 30 min and explored the proteome and phosphoproteome. Our results showed that KPP regulated cardiomyocyte proteins associated with, but not limited to, apoptosis, muscle contraction, protein turnover, and the respiratory chain. We also reported that KPP led to AKT phosphorylation, activating AKT and its downstream target nitric oxide synthase. We also observed that KPP led to dephosphorylation of phospholamban (PLN) at its activation sites (S16 and T17), leading to reduced contractility of treated cardiomyocytes. Some cellular targets reported here for KPP (e.g., AKT, PLN, and ERK) have already been reported to protect the cardiac tissue from hypoxia-induced injury. Hence, this study suggests potential beneficial effects of this scorpion cryptide that needs to be further investigated, for example, as a drug lead for cardiac infarction.
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Affiliation(s)
- Diana P Goméz-Mendoza
- Departamento de Fisiologia e Biofisica, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Rafael Pereira Lemos
- Departamento de Fisiologia e Biofisica, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Itamar C G Jesus
- Departamento de Fisiologia e Biofisica, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Vladimir Gorshkov
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense 5230, Denmark
| | - Shaun M K McKinnie
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - John C Vederas
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Frank Kjeldsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense 5230, Denmark
| | - Silvia Guatimosim
- Departamento de Fisiologia e Biofisica, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Robson Augusto Santos
- Departamento de Fisiologia e Biofisica, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Adriano M C Pimenta
- Departamento de Bioquimica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Thiago Verano-Braga
- Departamento de Fisiologia e Biofisica, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
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9
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Lin YC, Lu YH, Lee YC, Hung CS, Lin JC. Altered expressions and splicing profiles of Acin1 transcripts differentially modulate brown adipogenesis through an alternative splicing mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194601. [PMID: 32629174 DOI: 10.1016/j.bbagrm.2020.194601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/26/2020] [Accepted: 06/28/2020] [Indexed: 10/23/2022]
Abstract
Apoptotic chromatin condensation inducer in the nucleus (also referred as Acin1) was first characterized as an RNA-binding protein involved in apoptosis. In later reports, Acin1 was identified as an auxiliary component of the exon junction complex (EJC) which is assembled throughout pre-messenger RNA splicing. In this study, results of whole-transcriptome analyses revealed reduced expressions and reprogrammed splicing profiles of Acin1 transcripts throughout development of brown adipose tissues (BATs) that execute non-shivering thermogenesis in small rodents and infants by consuming lipids. Depletion of endogenous Acin1 isoforms led to activation of brown adipogenic signatures in mouse C3H10T1/2 fibroblasts. Nevertheless, overexpressions of the Acin1-L or Acin1-S isoform exerted discriminative influences on brown adipogenesis and reprogramming of the expression of serine/arginine-rich splicing factor 3 (SRSF3) through an alternative splicing-coupled nonsense-mediated decay mechanism in a sequence-specific manner. Moreover, the Acin1-SRSF3 axis constitutes a regulatory pathway that participates in the brown adipocyte-related splicing network. Taken together, the interplay between accessory EJC components and splicing regulators constitutes an emerging mechanism for differentially manipulating the activity of brown adipogenesis via alternative splicing network.
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Affiliation(s)
- Ying-Chin Lin
- Department of Family Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Family Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Yi-Han Lu
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Yuan-Chii Lee
- Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, Taiwan
| | - Ching-Sheng Hung
- PhD Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Department of Laboratory Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Jung-Chun Lin
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; PhD Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Pulmonary Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
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10
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Jang S, Cook NJ, Pye VE, Bedwell GJ, Dudek AM, Singh PK, Cherepanov P, Engelman AN. Differential role for phosphorylation in alternative polyadenylation function versus nuclear import of SR-like protein CPSF6. Nucleic Acids Res 2019; 47:4663-4683. [PMID: 30916345 PMCID: PMC6511849 DOI: 10.1093/nar/gkz206] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 02/12/2019] [Accepted: 03/18/2019] [Indexed: 12/20/2022] Open
Abstract
Cleavage factor I mammalian (CFIm) complex, composed of cleavage and polyadenylation specificity factor 5 (CPSF5) and serine/arginine-like protein CPSF6, regulates alternative polyadenylation (APA). Loss of CFIm function results in proximal polyadenylation site usage, shortening mRNA 3' untranslated regions (UTRs). Although CPSF6 plays additional roles in human disease, its nuclear translocation mechanism remains unresolved. Two β-karyopherins, transportin (TNPO) 1 and TNPO3, can bind CPSF6 in vitro, and we demonstrate here that while the TNPO1 binding site is dispensable for CPSF6 nuclear import, the arginine/serine (RS)-like domain (RSLD) that mediates TNPO3 binding is critical. The crystal structure of the RSLD-TNPO3 complex revealed potential CPSF6 interaction residues, which were confirmed to mediate TNPO3 binding and CPSF6 nuclear import. Both binding and nuclear import were independent of RSLD phosphorylation, though a hyperphosphorylated mimetic mutant failed to bind TNPO3 and mislocalized to the cell cytoplasm. Although hypophosphorylated CPSF6 largely supported normal polyadenylation site usage, a significant number of mRNAs harbored unnaturally extended 3' UTRs, similar to what is observed when other APA regulators, such as CFIIm component proteins, are depleted. Our results clarify the mechanism of CPSF6 nuclear import and highlight differential roles for RSLD phosphorylation in nuclear translocation versus regulation of APA.
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Affiliation(s)
- Sooin Jang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Nicola J Cook
- Chromatin Structure and Mobile DNA, The Francis Crick Institute, London, NW1 1AT, UK
| | - Valerie E Pye
- Chromatin Structure and Mobile DNA, The Francis Crick Institute, London, NW1 1AT, UK
| | - Gregory J Bedwell
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Amanda M Dudek
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Parmit K Singh
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Peter Cherepanov
- Chromatin Structure and Mobile DNA, The Francis Crick Institute, London, NW1 1AT, UK
- Department of Medicine, Imperial College London, St-Mary's Campus, Norfolk Place, London, W2 1PG, UK
| | - Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
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11
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Rodríguez-Ulloa A, Ramos Y, Sánchez-Puente A, Perera Y, Musacchio-Lasa A, Fernández-de-Cossio J, Padrón G, López LJ, Besada V, Perea SE. The Combination of the CIGB-300 Anticancer Peptide and Cisplatin Modulates Proteins Related to Cell Survival, DNA Repair and Metastasis in a Lung Cancer Cell Line Model. CURR PROTEOMICS 2019. [DOI: 10.2174/1570164616666190126104325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
CIGB-300 is a pro-apoptotic peptide that abrogates CK2-mediated phosphorylation,
and can elicit synergistic interaction in vitro and in vivo when combined with certain anticancer
drugs.
Objective:
The combination of CIGB-300 with cisplatin is studied through data mining and expressionbased
proteomics to reveal the molecular basis of this interaction. Cisplatin resistance-associated proteins,
which have also been reported as CK2 substrates, were first identified by bioinformatic analyses.
Methods:
Data from these analyses suggested that the cisplatin resistance phenotype could be directly
improved by inhibiting CK2 phosphorylation on specific substrates. Furthermore, 157 proteins were
differentially modulated on the NCI-H125 lung cancer cell line in response to CIGB-300, cisplatin or
both drugs as determined by LC-MS/MS.
Results:
The expression of 28 cisplatin resistance-associated proteins was changed when cisplatin was
combined with CIGB-300. Overall, the proteins identified are also related to cell survival, cell proliferation
and metastasis. Furthermore, the CIGB-300 regulated proteome revealed proteins that were initially
involved in the mechanism of action of CIGB-300 and cisplatin as single agents.
Conclusion:
This is the first report describing the protein array modulated by combining CIGB-300
and cisplatin that will support the rationale for future clinical settings based on a multi-target cancer
therapy.
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Affiliation(s)
| | - Yassel Ramos
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Aniel Sánchez-Puente
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Yasser Perera
- Laboratory of Molecular Oncology, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Alexis Musacchio-Lasa
- Department of Bioinformatics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | | | - Gabriel Padrón
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Luis J.G. López
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Vladimir Besada
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Silvio E. Perea
- Laboratory of Molecular Oncology, Center for Genetic Engineering and Biotechnology, Havana, Cuba
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12
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AKT/protein kinase B associates with β-actin in the nucleus of melanoma cells. Biosci Rep 2019; 39:BSR20181312. [PMID: 30643008 PMCID: PMC6356016 DOI: 10.1042/bsr20181312] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 12/21/2018] [Accepted: 01/07/2019] [Indexed: 12/19/2022] Open
Abstract
The serine-threonine kinase AKT/PKB is a critical regulator of various essential cellular processes, and dysregulation of AKT has been implicated in many diseases, including cancer. Despite AKT action is known to function mainly in the cytoplasm, AKT has been reported to translocate to the nucleus. However, very little is known about the mechanism required for the nuclear import of AKT as well as its function in this cellular compartment. In the present study, we characterized the presence of endogenous nuclear AKT in human melanoma cells and addressed the possible role of AKT by exploring its potential association with key interaction nuclear partners. Confocal and Western blot analyses showed that both phosphorylated and non-phosphorylated forms of AKT are present in melanoma cells nuclei. Using mass spectrometry in combination with protein-crosslinking and co-immunoprecipitation, we identified a series of putative protein partners of nuclear AKT, including heterogeneous nuclear ribonucleoprotein (hnRNP), cytoskeleton proteins β-actin, γ-actin, β-actin-like 2 and vimentin. Confocal microscopy and biochemical analyses validated β-actin as a new nuclear AKT-interacting partner. Cofilin and active RNA Polymerase II, two proteins that have been described to interact and work in concert with nuclear actin in transcription regulation, were also found associated with nuclear AKT. Overall, the present study uncovered a yet unrecognized nuclear coupling of AKT and provides insights into the involvement of AKT in the interaction network of nuclear actin.
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13
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Fernandes H, Czapinska H, Grudziaz K, Bujnicki JM, Nowacka M. Crystal structure of human Acinus RNA recognition motif domain. PeerJ 2018; 6:e5163. [PMID: 30042883 PMCID: PMC6057467 DOI: 10.7717/peerj.5163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/14/2018] [Indexed: 12/13/2022] Open
Abstract
Acinus is an abundant nuclear protein involved in apoptosis and splicing. It has been implicated in inducing apoptotic chromatin condensation and DNA fragmentation during programmed cell death. Acinus undergoes activation by proteolytic cleavage that produces a truncated p17 form that comprises only the RNA recognition motif (RRM) domain. We have determined the crystal structure of the human Acinus RRM domain (AcRRM) at 1.65 Å resolution. It shows a classical four-stranded antiparallel β-sheet fold with two flanking α-helices and an additional, non-classical α-helix at the C-terminus, which harbors the caspase-3 target sequence that is cleaved during Acinus activation. In the structure, the C-terminal α-helix partially occludes the potential ligand binding surface of the β-sheet and hypothetically shields it from non-sequence specific interactions with RNA. Based on the comparison with other RRM-RNA complex structures, it is likely that the C-terminal α-helix changes its conformation with respect to the RRM core in order to enable RNA binding by Acinus.
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Affiliation(s)
- Humberto Fernandes
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.,Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Honorata Czapinska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Katarzyna Grudziaz
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Janusz M Bujnicki
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.,Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Martyna Nowacka
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
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14
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Tao Y, Yang G, Yang H, Song D, Hu L, Xie B, Wang H, Gao L, Gao M, Xu H, Xu Z, Wu X, Zhang Y, Zhu W, Zhan F, Shi J. TRIP13 impairs mitotic checkpoint surveillance and is associated with poor prognosis in multiple myeloma. Oncotarget 2018; 8:26718-26731. [PMID: 28157697 PMCID: PMC5432292 DOI: 10.18632/oncotarget.14957] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 01/10/2017] [Indexed: 11/25/2022] Open
Abstract
AAA-ATPase TRIP13 is one of the chromosome instability gene recently established in multiple myeloma (MM), the second most common and incurable hematological malignancy. However, the specific function of TRIP13 in MM is largely unknown. Using sequential gene expression profiling, we demonstrated that high TRIP13 expression levels were positively correlated with progression, disease relapse, and poor prognosis in MM patients. Overexpressing human TRIP13 in myeloma cells prompted cell growth and drug resistance, and overexpressing murine TRIP13, which shares 93% sequence identity with human TRIP13, led to colony formation of NIH/3T3 fibroblasts in vitro and tumor formation in vivo. Meanwhile, the knockdown of TRIP13 inhibited myeloma cell growth, induced cell apoptosis, and reduced tumor burden in xenograft MM mice. Mechanistically, we observed that the overexpression of TRIP13 abrogated the spindle checkpoint and induced proteasome-mediated degradation of MAD2 primarily through the Akt pathway. Thus, our results demonstrate that TRIP13 may serve as a biomarker for MM disease development and prognosis, making it a potential target for future therapies.
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Affiliation(s)
- Yi Tao
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Guang Yang
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Hongxing Yang
- Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, China.,Shanghai Chenshan Plant Science Research Center, Chienes Academy of Sciences, Shanghai 201602, China
| | - Dongliang Song
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Liangning Hu
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Bingqian Xie
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Houcai Wang
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Lu Gao
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Minjie Gao
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Hongwei Xu
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Zhijian Xu
- CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xiaosong Wu
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Yiwen Zhang
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
| | - Weiliang Zhu
- CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Fenghuang Zhan
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Jumei Shi
- Department of Hematology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, China
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15
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Kumar S, Cieplak P. Effect of phosphorylation and single nucleotide polymorphisms on caspase substrates processing. Apoptosis 2018; 23:194-200. [DOI: 10.1007/s10495-018-1442-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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16
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Nandi N, Tyra LK, Stenesen D, Krämer H. Stress-induced Cdk5 activity enhances cytoprotective basal autophagy in Drosophila melanogaster by phosphorylating acinus at serine 437. eLife 2017; 6:e30760. [PMID: 29227247 PMCID: PMC5760206 DOI: 10.7554/elife.30760] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/08/2017] [Indexed: 12/22/2022] Open
Abstract
Cdk5 is a post-mitotic kinase with complex roles in maintaining neuronal health. The various mechanisms by which Cdk5 inhibits and promotes neurodegeneration are still poorly understood. Here, we show that in Drosophila melanogaster Cdk5 regulates basal autophagy, a key mechanism suppressing neurodegeneration. In a targeted screen, Cdk5 genetically interacted with Acinus (Acn), a primarily nuclear protein, which promotes starvation-independent, basal autophagy. Loss of Cdk5, or its required cofactor p35, reduces S437-Acn phosphorylation, whereas Cdk5 gain-of-function increases pS437-Acn levels. The phospho-mimetic S437D mutation stabilizes Acn and promotes basal autophagy. In p35 mutants, basal autophagy and lifespan are reduced, but restored to near wild-type levels in the presence of stabilized AcnS437D. Expression of aggregation-prone polyQ-containing proteins or the Amyloid-β42 peptide, but not alpha-Synuclein, enhances Cdk5-dependent phosphorylation of S437-Acn. Our data indicate that Cdk5 is required to maintain the protective role of basal autophagy in the initial responses to a subset of neurodegenerative challenges.
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Affiliation(s)
- Nilay Nandi
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Lauren K Tyra
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Drew Stenesen
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Helmut Krämer
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
- Department of Cell BiologyUT Southwestern Medical CenterDallasUnited States
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17
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Deka B, Singh KK. Multifaceted Regulation of Gene Expression by the Apoptosis- and Splicing-Associated Protein Complex and Its Components. Int J Biol Sci 2017; 13:545-560. [PMID: 28539829 PMCID: PMC5441173 DOI: 10.7150/ijbs.18649] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/24/2017] [Indexed: 11/24/2022] Open
Abstract
The differential deposition of RNA-binding proteins (RBPs) on pre-mRNA mediates the processes of gene expression. One of the complexes containing RBPs that play a crucial part in RNA metabolism is the apoptosis-and splicing-associated protein (ASAP) complex. In this review, we present a summary of the structure of ASAP complex and its localization. Also, we discuss the findings by different groups on various functions of the subunits of the ASAP complex in RNA metabolism. The subunits of the ASAP complex are RNPS1, Acinus and SAP18. Originally, the ASAP complex was thought to link RNA processing with apoptosis. Further studies have shown the role of these components in RNA metabolism of cells, including transcription, splicing, translation and nonsense-mediated mRNA decay (NMD). In transcription, RNPS1 is involved in preventing the formation of R-loop, while Acinus and SAP18 suppress transcription with the help of histone deacetylase. On the one hand, individual components of the ASAP complex, namely RNPS1 and Acinus act as splicing activators, whereas on the other hand, in-vitro assay shows that the ASAP complex behaves as splicing repressor. In addition, the individual members of the ASAP complex associates with the exon junction complex (EJC) to play roles in splicing and translation. RNPS1 increases the translation efficiency by participating in the 3'end processing and polysome association of mRNAs. Similarly, during NMD RNPS1 aids in the recruitment of decay factors by interacting with EJC.
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Affiliation(s)
| | - Kusum Kumari Singh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India
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18
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Wang C, Zhao L, Su Q, Fan X, Wang Y, Gao S, Wang H, Chen H, Chan CB, Liu Z. Phosphorylation of MITF by AKT affects its downstream targets and causes TP53-dependent cell senescence. Int J Biochem Cell Biol 2016; 80:132-142. [PMID: 27702651 DOI: 10.1016/j.biocel.2016.09.029] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 07/24/2016] [Accepted: 09/30/2016] [Indexed: 02/05/2023]
Abstract
Microphthalmia-associated transcription factor (MITF) plays a crucial role in the melanogenesis and proliferation of melanocytes that is dependent on its abundance and modification. Here, we report that epidermal growth factor (EGF) induces senescence and cyclin-dependent kinase inhibitor 1A (CDKN1A) expression that is related to MITF. We found that MITF could bind TP53 to regulate CDKN1A. Furthermore, the interaction between MITF and TP53 is dependent on AKT activity. We found that AKT phosphorylates MITF at S510. Phosphorylated MITF S510 enhances its affinity to TP53 and promotes CDKN1A expression. Meanwhile, the unphosphorylative MITF promotes TYR expression. The levels of p-MITF-S510 are low in 90% human melanoma samples. Thus the level of p-MITF-S510 could be a possible diagnostic marker for melanoma. Our findings reveal a mechanism for regulating MITF functions in response to EGF stimulation and suggest a possible implementation for preventing the over proliferation of melanoma cells.
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Affiliation(s)
- Chenyao Wang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 20031, China
| | - Lu Zhao
- The Fourth Hospital of Hebei Medical University, 12 Jiankang Rd, Qiao Dong Qu, Shijiazhuang, Hebei, 050012, China
| | - Qian Su
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 20031, China; Department of Biochemistry and Molecular Biology, Institute of Basic Medicine, Hebei Medical University, 361 Zhongshan E Rd, Chang'an, Shijiazhuang, Hebei, 050017, China
| | - Xiaoyu Fan
- Hospital of Lanzhou Military Command, 333 South Binhe Road, Lanzhou 730050, China
| | - Ying Wang
- The Fourth Hospital of Hebei Medical University, 12 Jiankang Rd, Qiao Dong Qu, Shijiazhuang, Hebei, 050012, China
| | - Shunqiang Gao
- The Fourth Hospital of Hebei Medical University, 12 Jiankang Rd, Qiao Dong Qu, Shijiazhuang, Hebei, 050012, China
| | - Huafei Wang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 20031, China
| | - Huaiyong Chen
- Tianjin Haihe Hospital, Tianjin Institute of Respiratory Diseases, Jingu Road, Jinnan District, Tianjin, 300350, China
| | - Chi Bun Chan
- Department of Physiology, The University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 634a, Oklahoma City, OK 73104, USA; School of Biological Sciences, The University of Hong Kong, 5N09, Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong
| | - Zhixue Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 20031, China.
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19
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Rodor J, Pan Q, Blencowe BJ, Eyras E, Cáceres JF. The RNA-binding profile of Acinus, a peripheral component of the exon junction complex, reveals its role in splicing regulation. RNA (NEW YORK, N.Y.) 2016; 22:1411-26. [PMID: 27365209 PMCID: PMC4986896 DOI: 10.1261/rna.057158.116] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/24/2016] [Indexed: 05/21/2023]
Abstract
Acinus (apoptotic chromatin condensation inducer in the nucleus) is an RNA-binding protein (RBP) originally identified for its role in apoptosis. It was later found to be an auxiliary component of the exon junction complex (EJC), which is deposited at exon junctions as a consequence of pre-mRNA splicing. To uncover the cellular functions of Acinus and investigate its role in splicing, we mapped its endogenous RNA targets using the cross-linking immunoprecipitation protocol (iCLIP). We observed that Acinus binds to pre-mRNAs, associating specifically to a subset of suboptimal introns, but also to spliced mRNAs. We also confirmed the presence of Acinus as a peripheral factor of the EJC. RNA-seq was used to investigate changes in gene expression and alternative splicing following siRNA-mediated depletion of Acinus in HeLa cells. This analysis revealed that Acinus is preferentially required for the inclusion of specific alternative cassette exons and also controls the faithful splicing of a subset of introns. Moreover, a large number of splicing changes can be related to Acinus binding, suggesting a direct role of Acinus in exon and intron definition. In particular, Acinus regulates the splicing of DFFA/ICAD transcript, a major regulator of DNA fragmentation. Globally, the genome-wide identification of RNA targets of Acinus revealed its role in splicing regulation as well as its involvement in other cellular pathways, including cell cycle progression. Altogether, this study uncovers new cellular functions of an RBP transiently associated with the EJC.
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Affiliation(s)
- Julie Rodor
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - Qun Pan
- Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Benjamin J Blencowe
- Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Eduardo Eyras
- Universitat Pompeu Fabra, E08003, Barcelona, Spain Catalan Institution for Research and Advanced Studies (ICREA), E08010 Barcelona, Spain
| | - Javier F Cáceres
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
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20
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The pro-inflammatory cytokines IFNγ/TNFα increase chromogranin A-positive neuroendocrine cells in the colonic epithelium. Biochem J 2016; 473:3805-3818. [PMID: 27538402 DOI: 10.1042/bcj20160390] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/18/2016] [Indexed: 02/07/2023]
Abstract
The gastrointestinal tract is the largest hormone-producing organ in the body due to a specialized cell population called enteroendocrine cells (EECs). The number of EECs increases in the mucosa of inflammatory bowel disease patients; however, the mechanisms responsible for these changes remain unknown. Here, we show that the pro-inflammatory cytokines interferon γ (IFNγ) and tumor necrosis factor α (TNFα) or dextran sulfate sodium (DSS)-induced colitis increase the number of EECs producing chromogranin A (CgA) in the colonic mucosa of C57BL/6J mice. CgA-positive cells were non-proliferating cells enriched with inactive phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and autophagy markers. Moreover, inhibition of Akt and autophagy prevented the increase in CgA-positive cells after IFNγ/TNFα treatment. Similarly, we observed that CgA-positive cells in the colonic mucosa of patients with colitis expressed Akt and autophagy markers. These findings suggest that Akt signaling and autophagy control differentiation of the intestinal EEC lineage during inflammation.
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21
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Nandi N, Tyra LK, Krämer H. Activated Acinus boosts basal autophagy. Mol Cell Oncol 2016; 2:e995043. [PMID: 27308482 PMCID: PMC4905319 DOI: 10.4161/23723556.2014.995043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 12/01/2014] [Accepted: 12/02/2014] [Indexed: 11/22/2022]
Abstract
Acinus (Acn) is a nuclear protein that participates in the regulation of autophagy. Loss of Acn function prevents autophagy in starving cells. Conversely, Acn activation induces basal autophagy. This enhances the quality control functions of autophagy such as the removal of misfolded proteins, thereby reducing neurodegeneration and prolonging lifespan. Acn activity is enhanced by Akt1-mediated phosphorylation, which counteracts the cleavage of Acn by a caspase-3 homolog.
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Affiliation(s)
- Nilay Nandi
- Department of Neuroscience; UT Southwestern Medical Center ; Dallas, TX, USA
| | - Lauren K Tyra
- Department of Neuroscience; UT Southwestern Medical Center ; Dallas, TX, USA
| | - Helmut Krämer
- Department of Neuroscience; UT Southwestern Medical Center; Dallas, TX, USA; Department of Cell Biology; UT Southwestern Medical Center; Dallas, TX, USA
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22
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Wang F, Wendling KS, Soprano KJ, Soprano DR. The SAP motif and C-terminal RS- and RD/E-rich region influences the sub-nuclear localization of Acinus isoforms. J Cell Biochem 2015; 115:2165-74. [PMID: 25079509 DOI: 10.1002/jcb.24893] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 07/25/2014] [Indexed: 11/06/2022]
Abstract
Acinus has been reported to function in apoptosis, RNA processing and regulation of gene transcription including RA-dependent transcription. There are three different isoforms of Acinus termed Acinus-L, Acinus-S', and Acinus-S. The isoforms of Acinus differ in their N-terminus while the C-terminus is consistent in all isoforms. The sub-nuclear localization of Acinus-L and Acinus-S' was determined using fluorescence microscopy. Acinus-S' colocalizes with SC35 in nuclear speckles while Acinus-L localizes diffusely throughout the nucleoplasm. RA treatment has little effect on the sub-nuclear localization of Acinus-L and Acinus-S'. The domains/regions necessary for the distinct sub-nuclear localization of Acinus-L and Acinus-S' were identified. The speckled sub-nuclear localization of Acinus-S' is dependent on its C-terminal RS- and RD/E-rich region but is independent of the phosphorylation status of Ser-453 and Ser-604 within this region. The unique N-terminal SAP motif of Acinus-L is responsible for its diffuse localization in the nucleus. Moreover, the sub-nuclear localization of Acinus isoforms is affected by each other, which is determined by the combinatorial effect of the more potent SAP motif of Acinus-L and the C-terminal RS- and RD/E-rich region in all Acinus isoforms. The C-terminal RS- and RD/E-rich region of Acinus mediates the colocalization of Acinus isoforms as well as with its interacting protein RNPS1. In conclusion, the SAP motif is responsible for the difference in the nuclear localization between Acinus-L and Acinus-S'. This difference in the nuclear localization of Acinus-S' and Acinus-L may suggest that these two isoforms have different functional roles.
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Affiliation(s)
- Fang Wang
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
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Schwarz JJ, Wiese H, Tölle RC, Zarei M, Dengjel J, Warscheid B, Thedieck K. Functional Proteomics Identifies Acinus L as a Direct Insulin- and Amino Acid-Dependent Mammalian Target of Rapamycin Complex 1 (mTORC1) Substrate. Mol Cell Proteomics 2015; 14:2042-55. [PMID: 25907765 DOI: 10.1074/mcp.m114.045807] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Indexed: 12/31/2022] Open
Abstract
The serine/threonine kinase mammalian target of rapamycin (mTOR) governs growth, metabolism, and aging in response to insulin and amino acids (aa), and is often activated in metabolic disorders and cancer. Much is known about the regulatory signaling network that encompasses mTOR, but surprisingly few direct mTOR substrates have been established to date. To tackle this gap in our knowledge, we took advantage of a combined quantitative phosphoproteomic and interactomic strategy. We analyzed the insulin- and aa-responsive phosphoproteome upon inhibition of the mTOR complex 1 (mTORC1) component raptor, and investigated in parallel the interactome of endogenous mTOR. By overlaying these two datasets, we identified acinus L as a potential novel mTORC1 target. We confirmed acinus L as a direct mTORC1 substrate by co-immunoprecipitation and MS-enhanced kinase assays. Our study delineates a triple proteomics strategy of combined phosphoproteomics, interactomics, and MS-enhanced kinase assays for the de novo-identification of mTOR network components, and provides a rich source of potential novel mTOR interactors and targets for future investigation.
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Affiliation(s)
- Jennifer Jasmin Schwarz
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg
| | - Heike Wiese
- §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany
| | - Regine Charlotte Tölle
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany
| | - Mostafa Zarei
- ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Jörn Dengjel
- ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg; ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Bettina Warscheid
- §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany;
| | - Kathrin Thedieck
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; ‡‡Department of Pediatrics, University of Groningen, University Medical Center Groningen (UMCG), 9713 AV Groningen, The Netherlands; §§Department for Neurosciences, Faculty VI - School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129 Oldenburg, Germany
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Wang F, Soprano KJ, Soprano DR. Role of Acinus in regulating retinoic acid-responsive gene pre-mRNA splicing. J Cell Physiol 2015; 230:791-801. [PMID: 25205379 DOI: 10.1002/jcp.24804] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Accepted: 09/05/2014] [Indexed: 02/03/2023]
Abstract
Acinus-S' is a corepressor for retinoic acid receptor (RAR)-dependent gene transcription and has been suggested to be involved in RNA processing. In this study, the role of Acinus isoforms in regulating pre-mRNA splicing was explored using in vivo splicing assays. Both Acinus-L and Acinus-S', with the activity of Acinus-L higher than that of Acinus-S', increase the splicing of a retinoic acid (RA)-responsive minigene containing a weak 5' splice site but not a RA-responsive minigene containing a strong 5' splice site. RA treatment further enhances the splicing of the weak 5' splice site by Acinus in a dose- and time-dependent manner, suggesting a RA-dependent activity in addition to a RA-independent activity of Acinus. The RA-independent effect of Acinus occurs to varying degrees using minigene constructs containing several different promoters, while the RA-dependent splicing activity of Acinus is specific for transcripts derived from the minigene driven by a RA response element (RARE)-containing promoter. This suggests that the ligand-dependent splicing activity of Acinus is related to the RA-activated RAR bound to the RARE. The RRM domain is necessary for the RA-dependent splicing activity of Acinus and the RA-independent splicing activity of Acinus is repressed by RNPS1. Importantly, measurement of the splicing of endogenous human RARβ and Bcl-x in vivo demonstrates that Acinus stimulates the use of the weaker alternative 5' splice site of these two genes in a RA-dependent manner for RARβ and a RA-independent manner for Bcl-x. Taken together, these studies demonstrate that Acinus functions in both RAR-dependent splicing and RAR-dependent transcription.
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Affiliation(s)
- Fang Wang
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA
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25
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Nandi N, Tyra LK, Stenesen D, Krämer H. Acinus integrates AKT1 and subapoptotic caspase activities to regulate basal autophagy. ACTA ACUST UNITED AC 2014; 207:253-68. [PMID: 25332163 PMCID: PMC4210446 DOI: 10.1083/jcb.201404028] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
How cellular stresses up-regulate autophagy is not fully understood. One potential regulator is the Drosophila melanogaster protein Acinus (Acn), which is necessary for autophagy induction and triggers excess autophagy when overexpressed. We show that cell type-specific regulation of Acn depends on proteolysis by the caspase Dcp-1. Basal Dcp-1 activity in developing photoreceptors is sufficient for this cleavage without a need for apoptosis to elevate caspase activity. On the other hand, Acn was stabilized by loss of Dcp-1 function or by the presence of a mutation in Acn that eliminates its conserved caspase cleavage site. Acn stability also was regulated by AKT1-mediated phosphorylation. Flies that expressed stabilized forms of Acn, either the phosphomimetic Acn(S641,731D) or the caspase-resistant Acn(D527A), exhibited enhanced basal autophagy. Physiologically, these flies showed improvements in processes known to be autophagy dependent, including increased starvation resistance, reduced Huntingtin-induced neurodegeneration, and prolonged life span. These data indicate that AKT1 and caspase-dependent regulation of Acn stability adjusts basal autophagy levels.
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Affiliation(s)
- Nilay Nandi
- Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Lauren K Tyra
- Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Drew Stenesen
- Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Helmut Krämer
- Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390 Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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26
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Ahn JY. Neuroprotection signaling of nuclear akt in neuronal cells. Exp Neurobiol 2014; 23:200-6. [PMID: 25258566 PMCID: PMC4174610 DOI: 10.5607/en.2014.23.3.200] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 08/11/2014] [Accepted: 08/12/2014] [Indexed: 12/29/2022] Open
Abstract
Akt is one of the central kinases that perform a pivotal function in mediating survival signaling in a wide range of neuronal cell types in response to growth factor stimulation. The recent findings of a number of targets for Akt suggest that it prohibits neuronal death by both impinging on the cytoplasmic cell death machinery and by regulating nuclear proteins. The presence of active Akt in the nuclei of mammalian cells is no longer debatable, and this has been corroborated by the finding of multiple targets in the nucleus of PC12 cells. However, it is also clear that the nuclear Akt signaling exists independent of the cytosolic Akt signaling, thereby showing a distinctive feature of nuclear Akt signaling as opposed to its cytosolic counterpart. The principal objective of this review is to summarize our current state of knowledge regarding nuclear Akt signaling in neuronal survival, and to introduce current theories regarding the roles of nuclear Akt in neuron.
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Affiliation(s)
- Jee-Yin Ahn
- Department of Molecular Cell Biology, Center for Molecular Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea
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27
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Turowec JP, Zukowski SA, Knight JDR, Smalley DM, Graves LM, Johnson GL, Li SSC, Lajoie GA, Litchfield DW. An unbiased proteomic screen reveals caspase cleavage is positively and negatively regulated by substrate phosphorylation. Mol Cell Proteomics 2014; 13:1184-97. [PMID: 24556848 PMCID: PMC4014278 DOI: 10.1074/mcp.m113.037374] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Post-translational modifications of proteins regulate diverse cellular functions, with mounting evidence suggesting that hierarchical cross-talk between distinct modifications may fine-tune cellular responses. For example, in apoptosis, caspases promote cell death via cleavage of key structural and enzymatic proteins that in some instances is inhibited by phosphorylation near the scissile bond. In this study, we systematically investigated how protein phosphorylation affects susceptibility to caspase cleavage using an N-terminomic strategy, namely, a modified terminal amino isotopic labeling of substrates (TAILS) workflow, to identify proteins for which caspase-catalyzed cleavage is modulated by phosphatase treatment. We validated the effects of phosphorylation on three of the identified proteins and found that Yap1 and Golgin-160 exhibit decreased cleavage when phosphorylated, whereas cleavage of MST3 was promoted by phosphorylation. Furthermore, using synthetic peptides we systematically examined the influence of phosphoserine throughout the entirety of caspase-3, -7, and -8 recognition motifs and observed a general inhibitory effect of phosphorylation even at residues considered outside the classical consensus motif. Overall, our work demonstrates a role for phosphorylation in controlling caspase-mediated cleavage and shows that N-terminomic strategies can be tailored to study cross-talk between phosphorylation and proteolysis.
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Affiliation(s)
- Jacob P Turowec
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario N6A 5C1, Canada
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The nitric oxide-cGKII system relays death and survival signals during embryonic retinal development via AKT-induced CREB1 activation. Cell Death Differ 2014; 21:915-28. [PMID: 24531539 DOI: 10.1038/cdd.2014.11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 12/21/2013] [Accepted: 01/08/2014] [Indexed: 01/28/2023] Open
Abstract
During early neurogenesis, retinal neuronal cells display a conserved differentiation program in vertebrates. Previous studies established that nitric oxide (NO) and cGMP accumulation regulate essential events in retinal physiology. Here we used pharmacological and genetic loss-of-function to investigate the effects of NO and its downstream signaling pathway in the survival of developing avian retinal neurons in vitro and in vivo. Six-day-old (E6) chick retinal cells displayed increased calcium influx and produced higher amounts of NO when compared with E8 cells. L-arginine (substrate for NO biosynthesis) and S-nitroso-N-acetyl-D,L-penicillamine (SNAP; a nitrosothiol NO donor) promoted extensive cell death in E6 retinas, whereas in E8 both substances decreased apoptosis. The effect of NO at both periods was mediated by soluble guanylyl cyclase (sGC) and cGMP-dependent kinase (cGK) activation. In addition, shRNA-mediated cGKII knockdown prevented NO-induced cell death (E6) and cell survival (E8). This, NO-induced cell death or cell survival was not correlated with an early inhibition of retinal cell proliferation. E6 cells also responded differentially from E8 neurons regarding cyclic AMP-responsive element-binding protein (CREB) activation in the retina in vivo. NO strongly decreased nuclear phospho-CREB staining in E6 but it robustly enhanced CREB phosphorylation in the nuclei of E8 neurons, an effect that was completely abrogated by cGKII shRNAs at both embryonic stages. The ability of NO in regulating CREB differentially during retinal development relied on the capacity of cGKII in decreasing (E6) or increasing (E8) nuclear AKT (V-Akt murine thymoma viral oncogene) activation. Accordingly, inhibiting AKT prevented both cGKII shRNA-mediated CREB upregulation in E6 and SNAP-induced CREB activation in E8. Furthermore, shRNA-mediated in vivo cGKII or in vitro CREB1 knockdown confirmed that NO/cGKII dualistically regulated the downstream CREB1 pathway and caspase activation in the chick retina to modulate neuronal viability. These data demonstrate that NO-mediated cGKII signaling may function to control the viability of neuronal cells during early retinal development via AKT/CREB1 activity.
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Diehl N, Schaal H. Make yourself at home: viral hijacking of the PI3K/Akt signaling pathway. Viruses 2013; 5:3192-212. [PMID: 24351799 PMCID: PMC3967167 DOI: 10.3390/v5123192] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/03/2013] [Accepted: 12/05/2013] [Indexed: 01/04/2023] Open
Abstract
As viruses do not possess genes encoding for proteins required for translation, energy metabolism or membrane biosynthesis, they are classified as obligatory intracellular parasites that depend on a host cell to replicate. This genome limitation forces them to gain control over cellular processes to ensure their successful propagation. A diverse spectrum of virally encoded proteins tackling a broad spectrum of cellular pathways during most steps of the viral life cycle ranging from the host cell entry to viral protein translation has evolved. Since the host cell PI3K/Akt signaling pathway plays a critical regulatory role in many cellular processes including RNA processing, translation, autophagy and apoptosis, many viruses, in widely varying ways, target it. This review focuses on a number of remarkable examples of viral strategies, which exploit the PI3K/Akt signaling pathway for effective viral replication.
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Affiliation(s)
| | - Heiner Schaal
- Universitätsklinikum Düsseldorf, Institut für Virologie, Universitätsstraße 1, Düsseldorf 40225, Germany.
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30
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Scaffold attachment factor B1 regulates the androgen receptor in concert with the growth inhibitory kinase MST1 and the methyltransferase EZH2. Oncogene 2013; 33:3235-45. [PMID: 23893242 DOI: 10.1038/onc.2013.294] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 04/12/2013] [Accepted: 05/07/2013] [Indexed: 12/16/2022]
Abstract
The androgen receptor (AR) is a transcription factor that employs many diverse interactions with coregulatory proteins in normal physiology and in prostate cancer (PCa). The AR mediates cellular responses in association with chromatin complexes and kinase cascades. Here we report that the nuclear matrix protein, scaffold attachment factor B1 (SAFB1), regulates AR activity and AR levels in a manner that suggests its involvement in PCa. SAFB1 mRNA expression was lower in PCa in comparison with normal prostate tissue in a majority of publicly available RNA expression data sets. SAFB1 protein levels were also reduced with disease progression in a cohort of human PCa that included metastatic tumors. SAFB1 bound to AR and was phosphorylated by the MST1 (Hippo homolog) serine-threonine kinase, previously shown to be an AR repressor, and MST1 localization to AR-dependent promoters was inhibited by SAFB1 depletion. Knockdown of SAFB1 in androgen-dependent LNCaP PCa cells increased AR and prostate-specific antigen (PSA) levels, stimulated growth of cultured cells and subcutaneous xenografts and promoted a more aggressive phenotype, consistent with a repressive AR regulatory function. SAFB1 formed a complex with the histone methyltransferase EZH2 at AR-interacting chromatin sites in association with other polycomb repressive complex 2 (PRC2) proteins. We conclude that SAFB1 acts as a novel AR co-regulator at gene loci where signals from the MST1/Hippo and EZH2 pathways converge.
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31
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Park HS, Seong KM, Kim JY, Kim CS, Yang KH, Jin YW, Nam SY. Chronic low-dose radiation inhibits the cells death by cytotoxic high-dose radiation increasing the level of AKT and acinus proteins via NF-κB activation. Int J Radiat Biol 2013. [DOI: 10.3109/09553002.2013.754560] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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32
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Martelli AM, Tabellini G, Bressanin D, Ognibene A, Goto K, Cocco L, Evangelisti C. The emerging multiple roles of nuclear Akt. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:2168-78. [PMID: 22960641 DOI: 10.1016/j.bbamcr.2012.08.017] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 08/20/2012] [Accepted: 08/23/2012] [Indexed: 12/26/2022]
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33
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Hekman KE, Yu GY, Brown CD, Zhu H, Du X, Gervin K, Undlien DE, Peterson A, Stevanin G, Clark HB, Pulst SM, Bird TD, White KP, Gomez CM. A conserved eEF2 coding variant in SCA26 leads to loss of translational fidelity and increased susceptibility to proteostatic insult. Hum Mol Genet 2012; 21:5472-83. [PMID: 23001565 DOI: 10.1093/hmg/dds392] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The autosomal dominant spinocerebellar ataxias (SCAs) are a genetically heterogeneous group of disorders exhibiting cerebellar atrophy and Purkinje cell degeneration whose subtypes arise from 31 distinct genetic loci. Our group previously published the locus for SCA26 on chromosome 19p13.3. In this study, we performed targeted deep sequencing of the critical interval in order to identify candidate causative variants in individuals from the SCA26 family. We identified a single variant that co-segregates with the disease phenotype that produces a single amino acid substitution in eukaryotic elongation factor 2. This substitution, P596H, sits in a domain critical for maintaining reading frame during translation. The yeast equivalent, P580H EF2, demonstrated impaired translocation, detected as an increased rate of -1 programmed ribosomal frameshift read-through in a dual-luciferase assay for observing translational recoding. This substitution also results in a greater susceptibility to proteostatic disruption, as evidenced by a more robust activation of a reporter gene driven by unfolded protein response activation upon challenge with dithiothreitol or heat shock in our yeast model system. Our results present a compelling candidate mutation and mechanism for the pathogenesis of SCA26 and further support the role of proteostatic disruption in neurodegenerative diseases.
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Affiliation(s)
- Katherine E Hekman
- Department of Neurology, Institute for Genomics and Systems Biology, University of Chicago, Chicago, IL 60637, USA
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Huang Y, Jeong JS, Okamura J, Sook-Kim M, Zhu H, Guerrero-Preston R, Ratovitski EA. Global tumor protein p53/p63 interactome: making a case for cisplatin chemoresistance. Cell Cycle 2012; 11:2367-79. [PMID: 22672905 DOI: 10.4161/cc.20863] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cisplatin chemoresistance is a clinical problem that leads to treatment failure in various human epithelial cancers. Members of tumor protein (TP) p53 family play various critical roles in the multiple molecular mechanisms underlying the chemoresistance of tumor cells. However, the in-depth mechanisms of the cellular response to cisplatin-induced cell death are still under thorough investigation. We previously showed that squamous cell carcinoma (SCC) cells exposed to cisplatin display an ATM-dependent phosphorylation of ΔNp63α, leading to a specific function of the phosphorylated (p)-ΔNp63α transcription factor in cisplatin-sensitive tumor cells. We further found that SCC cells expressing non-p-ΔNp63α-S385G became cisplatin-resistant. Using quantitative mass-spectrometry of protein complexes labeled with isobaric tags, we showed that TP53 and ΔNp63α are involved in numerous protein-protein interactions, which are likely to be implicated in the response of tumor cells to cisplatin exposure. We found that p-ΔNp63α binds to the splicing complex, leading to repression of mRNA splicing and activation of ACIN1-mediated cell death pathway. In contrast to p-ΔNp63α, non-p-ΔNp63α fails to bind the critical members of the splicing complex, thereby leading to activation of RNA splicing and reduction of cell death pathway. Overall, our studies provide an integrated proteomic platform in making a case for the role of the p53/p63 interactome in cisplatin chemoresistance.
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Affiliation(s)
- Yiping Huang
- Department of Dermatology, Institute of Basic Biomedical Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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35
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Lalic H, Lukinovic-Skudar V, Banfic H, Visnjic D. Rapamycin enhances dimethyl sulfoxide-mediated growth arrest in human myelogenous leukemia cells. Leuk Lymphoma 2012; 53:2253-61. [DOI: 10.3109/10428194.2012.684351] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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36
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Bononi A, Agnoletto C, De Marchi E, Marchi S, Patergnani S, Bonora M, Giorgi C, Missiroli S, Poletti F, Rimessi A, Pinton P. Protein kinases and phosphatases in the control of cell fate. Enzyme Res 2011; 2011:329098. [PMID: 21904669 PMCID: PMC3166778 DOI: 10.4061/2011/329098] [Citation(s) in RCA: 209] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/06/2011] [Accepted: 06/08/2011] [Indexed: 12/19/2022] Open
Abstract
Protein phosphorylation controls many aspects of cell fate and is often deregulated in pathological conditions. Several recent findings have provided an intriguing insight into the spatial regulation of protein phosphorylation across different subcellular compartments and how this can be finely orchestrated by specific kinases and phosphatases. In this review, the focus will be placed on (i) the phosphoinositide 3-kinase (PI3K) pathway, specifically on the kinases Akt and mTOR and on the phosphatases PP2a and PTEN, and on (ii) the PKC family of serine/threonine kinases. We will look at general aspects of cell physiology controlled by these kinases and phosphatases, highlighting the signalling pathways that drive cell division, proliferation, and apoptosis.
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Affiliation(s)
- Angela Bononi
- Section of General Pathology, Department of Experimental and Diagnostic Medicine, Interdisciplinary Center for the Study of Inflammation (ICSI) and LTTA Center, University of Ferrara, 44100 Ferrara, Italy
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37
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Turowec JP, Duncan JS, Gloor GB, Litchfield DW. Regulation of caspase pathways by protein kinase CK2: identification of proteins with overlapping CK2 and caspase consensus motifs. Mol Cell Biochem 2011; 356:159-67. [PMID: 21750976 DOI: 10.1007/s11010-011-0972-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 06/24/2011] [Indexed: 12/19/2022]
Abstract
Apoptosis, or programmed cell death, is a vital cellular process often impaired in diseases such as cancer. Aspartic acid-directed proteases known as caspases cleave a broad spectrum of cellular proteins and are central constituents of the apoptotic machinery. Caspases are regulated by a variety of mechanisms including protein phosphorylation. One intriguing mechanism by which protein kinases can modulate caspase pathways is by blocking substrate cleavage through phosphorylation of residues adjacent to caspase cleavage sites. To explore this mechanism in detail, we recently undertook a systematic investigation using a combination of bioinformatics, peptide arrays, and peptide cleavage assays to identify proteins with overlapping protein kinase and caspase recognition motifs (Duncan et al., Sci Signal 4:ra30, 2011). These studies implicated protein kinase CK2 as a global regulator of apoptotic pathways. In this article, we extend the analysis of proteins with overlapping CK2 and caspase consensus motifs to examine the convergence of CK2 with specific caspases and to identify CK2/caspase substrates known to be phosphorylated or cleaved in cells. Given its constitutive activity and elevated expression in cancer, these observations suggest that the ability of CK2 to modulate caspase pathways may contribute to a role in promoting cancer cell survival and raise interesting prospects for therapeutic targeting of CK2.
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Affiliation(s)
- Jacob P Turowec
- Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada
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38
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Nuclear but not cytosolic phosphoinositide 3-kinase beta has an essential function in cell survival. Mol Cell Biol 2011; 31:2122-33. [PMID: 21383062 DOI: 10.1128/mcb.01313-10] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Class I(A) phosphoinositide 3-kinases (PI3Ks) are heterodimeric enzymes composed of a p85 regulatory and a p110 catalytic subunit that induce the formation of 3-polyphosphoinositides, which mediate cell survival, division, and migration. There are two ubiquitous PI3K isoforms p110α and p110β that have nonredundant functions in embryonic development and cell division. However, whereas p110α concentrates in the cytoplasm, p110β localizes to the nucleus and modulates nuclear processes such as DNA replication and repair. At present, the structural features that determine p110β nuclear localization remain unknown. We describe here that association with the p85β regulatory subunit controls p110β nuclear localization. We identified a nuclear localization signal (NLS) in p110β C2 domain that mediates its nuclear entry, as well as a nuclear export sequence (NES) in p85β. Deletion of p110β induced apoptosis, and complementation with the cytoplasmic C2-NLS p110β mutant was unable to restore cell survival. These studies show that p110β NLS and p85β NES regulate p85β/p110β nuclear localization, supporting the idea that nuclear, but not cytoplasmic, p110β controls cell survival.
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Singh KK, Erkelenz S, Rattay S, Dehof AK, Hildebrandt A, Schulze-Osthoff K, Schaal H, Schwerk C. Human SAP18 mediates assembly of a splicing regulatory multiprotein complex via its ubiquitin-like fold. RNA (NEW YORK, N.Y.) 2010; 16:2442-54. [PMID: 20966198 PMCID: PMC2995405 DOI: 10.1261/rna.2304410] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 09/16/2010] [Indexed: 05/20/2023]
Abstract
RNPS1, Acinus, and SAP18 form the apoptosis- and splicing-associated protein (ASAP) complex, which is also part of the exon junction complex. Whereas RNPS1 was originally identified as a general activator of mRNA processing, all three proteins have been found within functional spliceosomes. Both RNPS1 and Acinus contain typical motifs of splicing regulatory proteins including arginine/serine-rich domains. Due to the absence of such structural features, however, a function of SAP18 in splicing regulation is completely unknown. Here we have investigated splicing regulatory activities of the ASAP components. Whereas a full-length Acinus isoform displayed only limited splicing regulatory activity, both RNPS1 and, surprisingly, SAP18 strongly modulated splicing regulation. Detailed mutational analysis and three-dimensional modeling data revealed that the ubiquitin-like fold of SAP18 was required for efficient splicing regulatory activity. Coimmunoprecipitation and immunofluorescence experiments demonstrated that SAP18 assembles a nuclear speckle-localized splicing regulatory multiprotein complex including RNPS1 and Acinus via its ubiquitin-like fold. Our results therefore suggest a novel function of SAP18 in splicing regulation.
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Affiliation(s)
- Kusum K Singh
- Institute of Molecular Medicine, University of Düsseldorf, D-40225 Düsseldorf, Germany
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40
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Guha M, Fang JK, Monks R, Birnbaum MJ, Avadhani NG. Activation of Akt is essential for the propagation of mitochondrial respiratory stress signaling and activation of the transcriptional coactivator heterogeneous ribonucleoprotein A2. Mol Biol Cell 2010; 21:3578-89. [PMID: 20719961 PMCID: PMC2954122 DOI: 10.1091/mbc.e10-03-0192] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
This article shows that mitochondrial respiratory dysfunction activates a stress signaling that induces Akt1 activation. Akt1 activation occurs through calcineurin-mediated IGF1R/PI3-K pathway. Akt1-mediated phosphorylation of hnRNPA2 is a key requirement for the propagation of stress signaling and activation of nuclear target genes. Mitochondrial respiratory stress (also called mitochondrial retrograde signaling) activates a Ca2+/calcineurin-mediated signal that culminates in transcription activation/repression of a large number of nuclear genes. This signal is propagated through activation of the regulatory proteins NFκB c-Rel/p50, C/EBPδ, CREB, and NFAT. Additionally, the heterogeneous ribonucleoprotein A2 (hnRNPA2) functions as a coactivator in up-regulating the transcription of Cathepsin L, RyR1, and Glut-4, the target genes of stress signaling. Activation of IGF1R, which causes a metabolic switch to glycolysis, cell invasiveness, and resistance to apoptosis, is a phenotypic hallmark of C2C12 myoblasts subjected to mitochondrial stress. In this study, we report that mitochondrial stress leads to increased expression, activation, and nuclear localization of Akt1. Mitochondrial respiratory stress also activates Akt1-gene expression, which involves hnRNPA2 as a coactivator, indicating a complex interdependency of these two factors. Using Akt1−/− mouse embryonic fibroblasts and Akt1 mRNA-silenced C2C12 cells, we show that Akt1-mediated phosphorylation is crucial for the activation and recruitment of hnRNPA2 to the enhanceosome complex. Akt1 mRNA silencing in mtDNA-depleted cells resulted in reversal of the invasive phenotype, accompanied by sensitivity to apoptotic stimuli. These results show that Akt1 is an important regulator of the nuclear transcriptional response to mitochondrial stress.
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Affiliation(s)
- Manti Guha
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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41
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Nam SY, Seo HH, Park HS, An S, Kim JY, Yang KH, Kim CS, Jeong M, Jin YW. Phosphorylation of CLK2 at serine 34 and threonine 127 by AKT controls cell survival after ionizing radiation. J Biol Chem 2010; 285:31157-63. [PMID: 20682768 DOI: 10.1074/jbc.m110.122044] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
AKT phosphorylates components of the intrinsic cell survival machinery and promotes survival to various stimuli. In the present study, we identified CDC-like kinase 2 (CLK2) as a new substrate of AKT activation and elucidated its role in cell survival to ionizing radiation. AKT directly binds to and phosphorylates CLK2 on serine 34 and threonine 127, in vitro and in vivo. CLK2 phosphorylation was detected in HeLa cells overexpressing active AKT. In addition, we demonstrated that ionizing radiation induces CLK2 phosphorylation via AKT activation. In contrast, the suppression of endogenous AKT expression by siRNA inhibited CLK2 phosphorylation in response to 2 gray of γ-ray or insulin. Furthermore, we examined the effect of CLK2 on the survival of irradiated CCD-18Lu cells overexpressing Myc-CLK2. CLK2 overexpression significantly increased cell growth and inhibited cell death induced by 2 gray. The role of CLK2 in cell survival to ionizing radiation was dependent on the phosphorylation of serine 34 and threonine 127. Our results suggest that AKT activation controls cell survival to ionizing radiation by phosphorylating CLK2, revealing an important regulatory mechanism required for promoting cell survival.
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Affiliation(s)
- Seon Young Nam
- Radiation Health Research Institute, Korea Hydro & Nuclear Power Co, Ltd, Seoul 132-703, Korea.
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42
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Lee SB, Kwon IS, Park J, Lee KH, Ahn Y, Lee C, Kim J, Choi SY, Cho SW, Ahn JY. Ribosomal protein S3, a new substrate of Akt, serves as a signal mediator between neuronal apoptosis and DNA repair. J Biol Chem 2010; 285:29457-68. [PMID: 20605787 DOI: 10.1074/jbc.m110.131367] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RPS3, a conserved, eukaryotic ribosomal protein of the 40 S subunit, is required for ribosome biogenesis. Because ribosomal proteins are abundant and ubiquitous, they may have additional extraribosomal functions. Here, we show that human RPS3 is a physiological target of Akt kinase and a novel mediator of neuronal apoptosis. NGF stimulation resulted in phosphorylation of threonine 70 of RPS3 by Akt, and this phosphorylation was required for Akt binding to RPS3. RPS3 induced neuronal apoptosis, up-regulating proapoptotic proteins Dp5/Hrk and Bim by binding to E2F1 and acting synergistically with it. Akt-dependent phosphorylation of RPS3 inhibited its proapoptotic function and perturbed its interaction with E2F1. These events coincided with nuclear translocation and accumulation of RPS3, where it functions as an endonuclease. Nuclear accumulation of RPS3 results in an increase in DNA repair activity to some extent, thereby sustaining neuronal survival. Abolishment of Akt-mediated RPS3 phosphorylation through mutagenesis accelerated apoptotic cell death and severely compromised nuclear translocation of RPS3. Thus, our findings define an extraribosomal role of RPS3 as a molecular switch that accommodates apoptotic induction to DNA repair through Akt-mediated phosphorylation.
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Affiliation(s)
- Sang Bae Lee
- Department of Molecular Cell Biology, Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea
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43
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Haberman AS, Akbar MA, Ray S, Krämer H. Drosophila acinus encodes a novel regulator of endocytic and autophagic trafficking. Development 2010; 137:2157-66. [PMID: 20504956 DOI: 10.1242/dev.044230] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Endosomal trafficking affects many cellular pathways from cell signaling to metabolism, but little is known about how these effects are coordinated. In a genetic screen for mutants affecting endosomal trafficking, we identified Drosophila acinus (dacn; hook-like). Its mammalian homolog Acinus has been implicated in RNA processing and chromatin fragmentation during apoptosis. Loss-of-function analysis of dacn revealed two distinct functions. First, dacn is required for stabilization of early endosomes, thus modulating levels of Notch and Egfr signaling. Second, loss of dacn interferes with cellular starvation responses by inhibiting autophagosome maturation. By contrast, overexpression of dacn causes lethality due to enhanced autophagy. We show that this enhanced autophagy is independent of the Tor pathway. Taken together, our data show that dacn encodes a regulator of endosomal and autophagosomal dynamics, modulating developmental signaling and the cellular response to starvation.
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Affiliation(s)
- Adam S Haberman
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390-9111, USA
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Ham BM, Jayachandran H, Yang F, Jaitly N, Polpitiya AD, Monroe ME, Wang L, Zhao R, Purvine SO, Livesay EA, Camp DG, Rossie S, Smith RD. Novel Ser/Thr protein phosphatase 5 (PP5) regulated targets during DNA damage identified by proteomics analysis. J Proteome Res 2010; 9:945-53. [PMID: 20039704 DOI: 10.1021/pr9008207] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The DNA damage response likely includes a global phosphorylation signaling cascade process for sensing the damaged DNA condition and coordinating responses to cope with and repair the perturbed cellular state. We utilized a label-free liquid chromatography-mass spectrometry approach to evaluate changes in protein phosphorylation associated with PP5 activity during the DNA damage response. Biological replicate analyses of bleomycin-treated HeLa cells expressing either WT-PP5 or mutant inactive PP5 lead to the identification of six potential target proteins of PP5 action. Four of these putative targets have been previously reported to be involved in DNA damage responses. Using phospho-site specific antibodies, we confirmed that phosphorylation of one target, ribosomal protein S6, was selectively decreased in cells overexpressing catalytically inactive PP5. Our findings also suggest that PP5 may play a role in controlling translation and in regulating substrates for proline-directed kinases, such as MAP kinases and cyclin-dependent protein kinases that are involved in response to DNA damage.
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Affiliation(s)
- Bryan M Ham
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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Kwon IS, Lee KH, Choi JW, Ahn JY. PI(3,4,5)P3 regulates the interaction between Akt and B23 in the nucleus. BMB Rep 2010; 43:127-32. [DOI: 10.5483/bmbrep.2010.43.2.127] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Abstract
IMPORTANCE OF THE FIELD Since its discovery in 1997, the antiapoptotic factor AAC-11 has rapidly gained attention due to its potential use in cancer therapy. Indeed, most cancer cells express elevated levels of AAC-11, which is now known to be involved in both tumor cells growth as well as sensitivity to chemotherapeutic drugs. AREAS COVERED IN THIS REVIEW In this review, we examine the most recent evidence about the role of AAC-11 in cancer biology and the therapeutic perspectives associated with its specific targeting. For that purpose, literature dealing with AAC-11 in the PubMed database was reviewed from 1997 up to date. WHAT THE READER WILL GAIN AAC-11 is an antiapoptotic gene that has the potential to be a target for anti-cancer therapy, and warrants further investigation. As its expression seems to predict unfavorable prognosis, at least in some cancers, it also may become a potent prognostic marker. TAKE HOME MESSAGE Blocking AAC-11 function in cancer for therapeutic purposes might be of great interest. The recent report of efficient AAC-11 inhibiting peptides that sensitize tumor cells to chemotherapeutic drugs has raise the exciting notion that AAC-11 might be a druggable target and fueled the search for new therapeutic agents that could block AAC-11 function.
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Affiliation(s)
- Audrey Faye
- INSERM UMRS 940, Equipe Avenir, Université Paris 7, Institut de Génétique Moléculaire, 75010 Paris, France
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Burattini S, Ferri P, Battistelli M, D'Emilio A, Biagiotti L, Sestili P, Rocchi MBL, Falcieri E. Apoptotic DNA fragmentation can be revealed in situ: an ultrastructural approach. Microsc Res Tech 2010; 72:913-23. [PMID: 19484747 DOI: 10.1002/jemt.20735] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A common pattern of apoptotic death is DNA cleavage, initially producing large fragments (50 kbp), followed by the production of nucleosomic/oligonucleosomic fragments. Nevertheless, apoptosis without DNA fragmentation, at least of the nucleosomic type, has been reported. To investigate the spatial relationship between DNA cleavage and chromatin condensation, we applied the TUNEL technique to the ultrastructural analysis of apoptotic cells. A modified method, utilizing a gold-conjugated antidigoxigenin antibody, was carried out on U937 versus Molt-4 cells, both exposed to UVB radiation or staurosporine treatment. Gold particle density in the different domains of apoptotic cells was evaluated by a four-way ANOVA test. Gold labelling was more strongly localised in condensed chromatin than in the diffuse chromatin. U937 cells, which evidenced in vitro oligonucleosomic fragmentation after both UVB and staurosporine treatments, revealed a significantly higher gold particle density, when compared with Molt-4, which did not show, on the other hand, oligonucleosomic cleavage even in the presence of < or = 50 kbp cleavage. Thus, a correlation between DNA fragment sizes and gold particle density appears. TUNEL applied to electron microscopy is an effective approach to study the relationship between apoptotic chromatin condensation and DNA cleavage. Both these events indeed appear in the apoptotic nucleus, but their reciprocal correlation is still greatly unknown. Microsc. Res. Tech. 2009. (c) 2009 Wiley-Liss, Inc.
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Affiliation(s)
- Sabrina Burattini
- Di.SUAN, Università degli Studi di Urbino Carlo Bo, I-61029 Urbino, Italy
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Park HS, Yun Y, Kim CS, Yang KH, Jeong M, Ahn SK, Jin YW, Nam SY. A critical role for AKT activation in protecting cells from ionizing radiation-induced apoptosis and the regulation of acinus gene expression. Eur J Cell Biol 2009; 88:563-75. [DOI: 10.1016/j.ejcb.2009.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Revised: 05/11/2009] [Accepted: 05/11/2009] [Indexed: 01/01/2023] Open
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49
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Choudhary C, Olsen JV, Brandts C, Cox J, Reddy PN, Böhmer FD, Gerke V, Schmidt-Arras DE, Berdel WE, Müller-Tidow C, Mann M, Serve H. Mislocalized Activation of Oncogenic RTKs Switches Downstream Signaling Outcomes. Mol Cell 2009; 36:326-39. [DOI: 10.1016/j.molcel.2009.09.019] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 06/19/2009] [Accepted: 09/10/2009] [Indexed: 10/20/2022]
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50
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NGF inhibits human leukemia proliferation by downregulating cyclin A1 expression through promoting acinus/CtBP2 association. Oncogene 2009; 28:3825-36. [PMID: 19668232 PMCID: PMC3481846 DOI: 10.1038/onc.2009.236] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cyclin A1 is essential for leukemia progression, and its expression is tightly regulated by acinus, a nuclear speckle protein. However, the molecular mechanism of how acinus mediates cyclin A1 expression remains elusive. Here we show that transcription corepressor CtBP2 directly binds acinus, which is regulated by nerve growth factor (NGF), inhibiting its stimulatory effect on cyclin A1, but not cyclin A2, expression in leukemia. NGF, a cognate ligand for the neurotrophic receptor TrkA, promotes the interaction between CtBP2 and acinus through triggering acinus phosphorylation by Akt. Overexpression of CtBP2 diminishes cyclin A1 transcription, whereas depletion of CtBP2 abolishes NGF's suppressive effect on cyclin A1 expression. Strikingly, gambogic amide, a newly identified TrkA agonist, potently represses cyclin A1 expression, thus blocking K562 cell proliferation. Moreover, gambogic amide ameliorates the leukemia progression in K562 cells inoculated nude mice. Hence, NGF downregulates cyclin A1 expression through escalating CtBP2/acinus complex formation, and gambogic amide might be useful for human leukemia treatment.
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