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Hassan M, Yasir M, Shahzadi S, Chun W, Kloczkowski A. Molecular Role of Protein Phosphatases in Alzheimer's and Other Neurodegenerative Diseases. Biomedicines 2024; 12:1097. [PMID: 38791058 PMCID: PMC11117500 DOI: 10.3390/biomedicines12051097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/02/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
Alzheimer's disease (AD) is distinguished by the gradual loss of cognitive function, which is associated with neuronal loss and death. Accumulating evidence supports that protein phosphatases (PPs; PP1, PP2A, PP2B, PP4, PP5, PP6, and PP7) are directly linked with amyloid beta (Aβ) as well as the formation of the neurofibrillary tangles (NFTs) causing AD. Published data reported lower PP1 and PP2A activity in both gray and white matters in AD brains than in the controls, which clearly shows that dysfunctional phosphatases play a significant role in AD. Moreover, PP2A is also a major causing factor of AD through the deregulation of the tau protein. Here, we review recent advances on the role of protein phosphatases in the pathology of AD and other neurodegenerative diseases. A better understanding of this problem may lead to the development of phosphatase-targeted therapies for neurodegenerative disorders in the near future.
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Affiliation(s)
- Mubashir Hassan
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children’s Hospital, Columbus, OH 43205, USA;
| | - Muhammad Yasir
- Department of Pharmacology, Kangwon National University School of Medicine, Chuncheon 24341, Republic of Korea; (M.Y.); (W.C.)
| | - Saba Shahzadi
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children’s Hospital, Columbus, OH 43205, USA;
| | - Wanjoo Chun
- Department of Pharmacology, Kangwon National University School of Medicine, Chuncheon 24341, Republic of Korea; (M.Y.); (W.C.)
| | - Andrzej Kloczkowski
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children’s Hospital, Columbus, OH 43205, USA;
- Department of Pediatrics, The Ohio State University, Columbus, OH 43205, USA
- Department of Biomedical Informatics, The Ohio State University, Columbus, OH 43210, USA
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Nadel G, Yao Z, Hacohen-Lev-Ran A, Wainstein E, Maik-Rachline G, Ziv T, Naor Z, Admon A, Seger R. Phosphorylation of PP2Ac by PKC is a key regulatory step in the PP2A-switch-dependent AKT dephosphorylation that leads to apoptosis. Cell Commun Signal 2024; 22:154. [PMID: 38419089 PMCID: PMC10900696 DOI: 10.1186/s12964-024-01536-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 02/17/2024] [Indexed: 03/02/2024] Open
Abstract
BACKGROUND Although GqPCR activation often leads to cell survival by activating the PI3K/AKT pathway, it was previously shown that in several cell types AKT activity is reduced and leads to JNK activation and apoptosis. The mechanism of AKT inactivation in these cells involves an IGBP1-coupled PP2Ac switch that induces the dephosphorylation and inactivation of both PI3K and AKT. However, the machinery involved in the initiation of PP2A switch is not known. METHODS We used phospho-mass spectrometry to identify the phosphorylation site of PP2Ac, and raised specific antibodies to follow the regulation of this phosphorylation. Other phosphorylations were monitored by commercial antibodies. In addition, we used coimmunoprecipitation and proximity ligation assays to follow protein-protein interactions. Apoptosis was detected by a TUNEL assay as well as PARP1 cleavage using SDS-PAGE and Western blotting. RESULTS We identified Ser24 as a phosphorylation site in PP2Ac. The phosphorylation is mediated mainly by classical PKCs (PKCα and PKCβ) but not by novel PKCs (PKCδ and PKCε). By replacing the phosphorylated residue with either unphosphorylatable or phosphomimetic residues (S24A and S24E), we found that this phosphorylation event is necessary and sufficient to mediate the PP2A switch, which ultimately induces AKT inactivation, and a robust JNK-dependent apoptosis. CONCLUSION Our results show that the PP2A switch is induced by PKC-mediated phosphorylation of Ser24-PP2Ac and that this phosphorylation leads to apoptosis upon GqPCR induction of various cells. We propose that this mechanism may provide an unexpected way to treat some cancer types or problems in the endocrine machinery.
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Affiliation(s)
- Guy Nadel
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Zhong Yao
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Avital Hacohen-Lev-Ran
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Ehud Wainstein
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Galia Maik-Rachline
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Ziv
- Smoler Proteomic Center, Technion-Israel Institute of Technology, Haifa, Israel
| | - Zvi Naor
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel
| | - Arie Admon
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Rony Seger
- Department of Immunology and Regenerative Biology, the Weizmann Institute of Science, Rehovot, Israel.
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3
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Ikeda S, Sato K, Ohama T. Transcriptome analysis revealed that PME-1 suppresses inflammatory signaling, activates PI3K/Akt signaling, and promotes epithelial-mesenchymal transition. Biochem Biophys Res Commun 2024; 692:149148. [PMID: 38043157 DOI: 10.1016/j.bbrc.2023.149148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 09/28/2023] [Accepted: 10/23/2023] [Indexed: 12/05/2023]
Abstract
Protein phosphatase 2A (PP2A) is an essential serine/threonine protein phosphatase that belongs to the type2A protein phosphatase family with PP4 and PP6. PP2A functions as a trimeric holoenzyme, and the composition of the trimer is regulated by the methyl-esterification (methylation) of PP2A. Demethylation of PP2A is catalyzed by protein phosphatase methyl-esterase-1 (PME-1). Despite the physiological and pathophysiological importance of PME-1, the impact of changes in PME-1 expression on the transcriptome has not been reported. This study provides transcriptome data to gain a comprehensive understanding of the effects of PME-1 knockout on intracellular signaling of mouse embryonic fibroblasts. Our data showed that PME-1 suppresses inflammatory signaling, activates PI3K/Akt signaling, and promotes epithelial-mesenchymal transition.
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Affiliation(s)
- Shunta Ikeda
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Koichi Sato
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Takashi Ohama
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.
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4
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Li C, Zhang P, Hong PP, Niu GJ, Wang XP, Zhao XF, Wang JX. White spot syndrome virus hijacks host PP2A-FOXO axes to promote its propagation. Int J Biol Macromol 2024; 256:128333. [PMID: 38007022 DOI: 10.1016/j.ijbiomac.2023.128333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 11/06/2023] [Accepted: 11/14/2023] [Indexed: 11/27/2023]
Abstract
Viruses have developed superior strategies to escape host defenses or exploit host components and enable their infection. The forkhead box transcription factor O family proteins (FOXOs) are reportedly utilized by human cytomegalovirus during their reactivation in mammals, but if FOXOs are exploited by viruses during their infection remains unclear. In the present study, we found that the FOXO of kuruma shrimp (Marsupenaeus japonicus) was hijacked by white spot syndrome virus (WSSV) during infection. Mechanistically, the expression of leucine carboxyl methyl transferase 1 (LCMT1) was up-regulated during the early stages of WSSV infection, which activated the protein phosphatase 2A (PP2A) by methylation, leading to dephosphorylation of FOXO and translocation into the nucleus. The FOXO directly promoted transcription of the immediate early gene, wsv079 of WSSV, which functioned as a transcriptional activator to initiate the expression of viral early and late genes. Thus, WSSV utilized the host LCMT1-PP2A-FOXO axis to promote its replication during the early infection stage. We also found that, during the late stages of WSSV infection, the envelope protein of WSSV (VP26) promoted PP2A activity by directly binding to FOXO and the regulatory subunit of PP2A (B55), which further facilitated FOXO dephosphorylation and WSSV replication via the VP26-PP2A-FOXO axis in shrimp. Overall, this study reveals novel viral strategies by which WSSV hijacks host LCMT1-PP2A-FOXO or VP26-PP2A-FOXO axes to promote its propagation, and provides clinical targets for WSSV control in shrimp aquaculture.
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Affiliation(s)
- Cang Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Peng Zhang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Pan-Pan Hong
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Guo-Juan Niu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Xiao-Pei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Xiao-Fan Zhao
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Jin-Xing Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China; State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong 266237, China.
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Ji N, Chen Z, Wang Z, Sun W, Yuan Q, Zhang X, Jia X, Wu J, Jiang J, Song M, Xu T, Liu Y, Ma Q, Sun Z, Bao Y, Zhang M, Huang M. LincR-PPP2R5C Promotes Th2 Cell Differentiation Through PPP2R5C/PP2A by Forming an RNA-DNA Triplex in Allergic Asthma. ALLERGY, ASTHMA & IMMUNOLOGY RESEARCH 2024; 16:71-90. [PMID: 38262392 PMCID: PMC10823138 DOI: 10.4168/aair.2024.16.1.71] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 08/13/2023] [Accepted: 08/22/2023] [Indexed: 01/25/2024]
Abstract
PURPOSE The roles and mechanisms of long noncoding RNAs (lncRNAs) in T helper 2 (Th2) differentiation from allergic asthma are poorly understood. We aimed to explore a novel lncRNA, LincR-protein phosphatase 2 regulatory subunit B' gamma (PPP2R5C), in Th2 differentiation in a mouse model of asthma. METHODS LincR-PPP2R5C from RNA-seq data of CD4+ T cells of asthma-like mice were validated and confirmed by quantitative reverse transcription polymerase chain reaction, northern blotting, nuclear and cytoplasmic separation, and fluorescence in situ hybridization (FISH). Lentiviruses encoding LincR-PPP2R5C or shRNA were used to overexpress or silence LincR-PPP2R5C in CD4+ T cells. The interactions between LincR-PPP2R5C and PPP2R5C were explored with western blotting, chromatin isolation by RNA purification assay, and fluorescence resonance energy transfer. An ovalbumin-induced acute asthma model in knockout (KO) mice (LincR-PPP2R5C KO, CD4 conditional LincR-PPP2R5C KO) was established to explore the roles of LincR-PPP2R5C in Th2 differentiation. RESULTS LncR-PPP2R5C was significantly higher in CD4+ T cells from asthmatic mice ex vivo and Th2 cells in vitro. The lentivirus encoding LincR-PPP2R5C suppressed Th1 differentiation; in contrast, the short hairpin RNA (shRNA) lentivirus decreased LincR-PPP2R5C and Th2 differentiation. Mechanistically, LincR-PPP2R5C deficiency suppressed the phosphatase activity of the protein phosphatase 2A (PP2A) holocomplex, resulting in a decline in Th2 differentiation. The formation of an RNA-DNA triplex between LincR-PPP2R5C and the PPP2R5C promoter enhanced PPP2R5C expression and activated PP2A. LincR-PPP2R5C KO and CD4 conditional KO decreased Th2 differentiation, airway hyperresponsiveness and inflammatory responses. CONCLUSIONS LincR-PPP2R5C regulated PPP2R5C expression and PP2A activity by forming an RNA-DNA triplex with the PPP2R5C promoter, leading to Th2 polarization in a mouse model of acute asthma. Our data presented the first definitive evidence of lncRNAs in the regulation of Th2 cells in asthma.
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Affiliation(s)
- Ningfei Ji
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Zhongqi Chen
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Zhengxia Wang
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Wei Sun
- Department of Respiratory and Critical Care Medicine, Xishan People's Hospital of Wuxi City, Wuxi Branch of Zhongda Hospital Affiliate to Southeast University, Wuxi, China
| | - Qi Yuan
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xijie Zhang
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xinyu Jia
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jingjing Wu
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jingxian Jiang
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Meijuan Song
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Tingting Xu
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yanan Liu
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Qiyun Ma
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Zhixiao Sun
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yanmin Bao
- Department of Respiratory Medicine, Shenzhen Children's Hospital, Shenzhen, China
| | - Mingshun Zhang
- Jiangsu Province Engineering Research Center of Antibody Drugs, NHC Key Laboratory of Antibody Technique, Department of Immunology, Nanjing Medical University, Nanjing, China.
| | - Mao Huang
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
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Claes Z, Bollen M. A split-luciferase lysate-based approach to identify small-molecule modulators of phosphatase subunit interactions. Cell Chem Biol 2023; 30:1666-1679.e6. [PMID: 37625414 DOI: 10.1016/j.chembiol.2023.07.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/31/2023] [Accepted: 07/30/2023] [Indexed: 08/27/2023]
Abstract
An emerging strategy for the therapeutic targeting of protein phosphatases involves the use of compounds that interfere with the binding of regulatory subunits or substrates. However, high-throughput screening strategies for such interfering molecules are scarce. Here, we report on the conversion of the NanoBiT split-luciferase system into a robust assay for the quantification of phosphatase subunit and substrate interactions in cell lysates. The assay is suitable to screen small-molecule libraries for interfering compounds. We designed and validated split-luciferase sensors for a broad range of PP1 and PP2A holoenzymes, including sensors that selectively report on weak interaction sites. To facilitate efficient hit triaging in large-scale screening campaigns, deselection procedures were developed to eliminate assay-interfering molecules with high fidelity. As a proof-of-principle, we successfully applied the split-luciferase screening tool to identify small-molecule disruptors of the interaction between the C-terminus of PP1β and the ankyrin-repeat domain of the myosin-phosphatase targeting subunit MYPT1.
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Affiliation(s)
- Zander Claes
- Laboratory of Biosignaling and Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, 3000 Leuven, Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling and Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, 3000 Leuven, Belgium.
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Ji YX, Hu S, Chen FX. Protocol for rapidly inducing genome-wide RNA Pol II hyperphosphorylation by selectively disrupting INTAC phosphatase activity. STAR Protoc 2023; 4:102640. [PMID: 37831607 PMCID: PMC10589876 DOI: 10.1016/j.xpro.2023.102640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/08/2023] [Accepted: 09/22/2023] [Indexed: 10/15/2023] Open
Abstract
While several inhibitors targeting RNA polymerase II (Pol II) kinases have been applied for inhibiting RNA Pol II phosphorylation, there are few approaches for inducing RNA Pol II hyperphosphorylation. Here, we present a protocol for constructing the INTS8 degradation tag (dTAG) system combined with ectopic expression of N-terminally truncated INTS8 (INTS8-ΔN) in DLD-1 cells. We describe steps for INTS8-dTAG cell line construction, validation of knockin and degradation, and INTS8-ΔN rescue. We then detail validation of RNA Pol II phosphorylation upregulation. For complete details on the use and execution of this protocol, please refer to Hu et al. (2023).1.
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Affiliation(s)
- Yu-Xin Ji
- Fudan University Shanghai Cancer Center, Shanghai Key Laboratory of Medical Epigenetics, Shanghai Key Laboratory of Radiation Oncology, Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Shibin Hu
- Fudan University Shanghai Cancer Center, Shanghai Key Laboratory of Medical Epigenetics, Shanghai Key Laboratory of Radiation Oncology, Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
| | - Fei Xavier Chen
- Fudan University Shanghai Cancer Center, Shanghai Key Laboratory of Medical Epigenetics, Shanghai Key Laboratory of Radiation Oncology, Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
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Cokelaere C, Dok R, Cortesi EE, Zhao P, Sablina A, Nuyts S, Derua R, Janssens V. TIPRL1 and its ATM-dependent phosphorylation promote radiotherapy resistance in head and neck cancer. Cell Oncol (Dordr) 2023:10.1007/s13402-023-00895-6. [PMID: 37971644 DOI: 10.1007/s13402-023-00895-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2023] [Indexed: 11/19/2023] Open
Abstract
PURPOSE TIPRL1 (target of rapamycin signaling pathway regulator-like 1) is a known interactor and inhibitor of protein phosphatases PP2A, PP4 and PP6 - all pleiotropic modulators of the DNA Damage Response (DDR). Here, we investigated the role of TIPRL1 in the radiotherapy (RT) response of Head and Neck Squamous Cell Carcinoma (HNSCC). METHODS TIPRL1 mRNA (cBioportal) and protein expression (immunohistochemistry) in HNSCC samples were linked with clinical patient data. TIPRL1-depleted HNSCC cells were generated by CRISPR/Cas9 editing, and effects on colony growth, micronuclei formation (microscopy), cell cycle (flow cytometry), DDR signaling (immunoblots) and proteome (mass spectrometry) following RT were assessed. Mass spectrometry was used for TIPRL1 phosphorylation and interactomics analysis in irradiated cells. RESULTS TIPRL1 expression was increased in tumor versus non-tumor tissue, with high tumoral TIPRL1 expression associating with lower locoregional control and decreased survival of RT-treated patients. TIPRL1 deletion in HNSCC cells resulted in increased RT sensitivity, a faster but prolonged cell cycle arrest, increased micronuclei formation and an altered proteome-wide DDR. Upon irradiation, ATM phosphorylates TIPRL1 at Ser265. A non-phospho Ser265Ala mutant could not rescue the increased radiosensitivity phenotype of TIPRL1-depleted cells. While binding to PP2A-like phosphatases was confirmed, DNA-dependent protein kinase (DNA-PKcs), RAD51 recombinase and nucleosomal histones were identified as novel TIPRL1 interactors. Histone binding, although stimulated by RT, was adversely affected by TIPRL1 Ser265 phosphorylation. CONCLUSIONS Our findings underscore a clinically relevant role for TIPRL1 and its ATM-dependent phosphorylation in RT resistance through modulation of the DDR, highlighting its potential as a new HNSCC predictive marker and therapeutic target.
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Affiliation(s)
- Célie Cokelaere
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), B-3000, Leuven, Belgium
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium
| | - Rüveyda Dok
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium
- Laboratory of Experimental Radiotherapy, Department of Oncology, University of Leuven (KU Leuven), B-3000, Leuven, Belgium
| | - Emanuela E Cortesi
- Translational Cell & Tissue Research, Department of Imaging & Pathology, University of Leuven (KU Leuven), B-3000, Leuven, Belgium
| | - Peihua Zhao
- VIB Laboratory of Mechanisms of Cell Transformation, Department of Oncology, University of Leuven (KU Leuven), B-3000, Leuven, Belgium
| | - Anna Sablina
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium
- VIB Laboratory of Mechanisms of Cell Transformation, Department of Oncology, University of Leuven (KU Leuven), B-3000, Leuven, Belgium
| | - Sandra Nuyts
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium
- Laboratory of Experimental Radiotherapy, Department of Oncology, University of Leuven (KU Leuven), B-3000, Leuven, Belgium
| | - Rita Derua
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), B-3000, Leuven, Belgium
- SybioMA, Proteomics Core Facility, University of Leuven (KU Leuven), B-3000, Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), B-3000, Leuven, Belgium.
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium.
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Peris I, Romero-Murillo S, Vicente C, Narla G, Odero MD. Regulation and role of the PP2A-B56 holoenzyme family in cancer. Biochim Biophys Acta Rev Cancer 2023; 1878:188953. [PMID: 37437699 DOI: 10.1016/j.bbcan.2023.188953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/07/2023] [Accepted: 07/08/2023] [Indexed: 07/14/2023]
Abstract
Protein phosphatase 2A (PP2A) inactivation is common in cancer, leading to sustained activation of pro-survival and growth-promoting pathways. PP2A consists of a scaffolding A-subunit, a catalytic C-subunit, and a regulatory B-subunit. The functional complexity of PP2A holoenzymes arises mainly through the vast repertoire of regulatory B-subunits, which determine both their substrate specificity and their subcellular localization. Therefore, a major challenge for developing more effective therapeutic strategies for cancer is to identify the specific PP2A complexes to be targeted. Of note, the development of small molecules specifically directed at PP2A-B56α has opened new therapeutic avenues in both solid and hematological tumors. Here, we focus on the B56/PR61 family of PP2A regulatory subunits, which have a central role in directing PP2A tumor suppressor activity. We provide an overview of the mechanisms controlling the formation and regulation of these complexes, the pathways they control, and the mechanisms underlying their deregulation in cancer.
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Affiliation(s)
- Irene Peris
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain.
| | - Silvia Romero-Murillo
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain
| | - Carmen Vicente
- Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, The University of Michigan Medical School, Ann Arbor, MI, USA
| | - Maria D Odero
- Department of Biochemistry and Genetics, University of Navarra, Pamplona, Spain; Centro de Investigación Médica Aplicada (CIMA), University of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Spain; CIBERONC, Instituto de Salud Carlos III, Madrid, Spain.
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10
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Smolen KA, Papke CM, Swingle MR, Musiyenko A, Li C, Salter EA, Camp AD, Honkanen RE, Kettenbach AN. Quantitative proteomics and phosphoproteomics of PP2A-PPP2R5D variants reveal deregulation of RPS6 phosphorylation via converging signaling cascades. J Biol Chem 2023; 299:105154. [PMID: 37572851 PMCID: PMC10485637 DOI: 10.1016/j.jbc.2023.105154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 07/28/2023] [Accepted: 07/29/2023] [Indexed: 08/14/2023] Open
Abstract
Genetic germline variants of PPP2R5D (encoding: phosphoprotein phosphatase 2 regulatory protein 5D) result in PPP2R5D-related disorder (Jordan's Syndrome), which is characterized by intellectual disability, hypotonia, seizures, macrocephaly, autism spectrum disorder, and delayed motor skill development. The disorder originates from de novo single nucleotide mutations, generating missense variants that act in a dominant manner. Pathogenic mutations altering 13 different amino acids have been identified, with the E198K variant accounting for ∼40% of reported cases. However, the generation of a heterozygous E198K variant cell line to study the molecular effects of the pathogenic mutation has been challenging. Here, we use CRISPR-PRIME genomic editing to introduce a transition (c.592G>A) in a single PPP2R5D allele in HEK293 cells, generating E198K-heterozygous lines to complement existing E420K variant lines. We generate global protein and phosphorylation profiles of WT, E198K, and E420K cell lines and find unique and shared changes between variants and WT cells in kinase- and phosphatase-controlled signaling cascades. We observed ribosomal protein S6 (RPS6) hyperphosphorylation as a shared signaling alteration, indicative of increased ribosomal protein S6-kinase activity. Treatment with rapamycin or an RPS6-kinase inhibitor (LY2584702) suppressed RPS6 phosphorylation in both, suggesting upstream activation of mTORC1/p70S6K. Intriguingly, our data suggests ERK-dependent activation of mTORC1 in both E198K and E420K variant cells, with additional AKT-mediated mTORC1 activation in the E420K variant. Thus, although upstream activation of mTORC1 differs between PPP2R5D-related disorder genotypes, inhibition of mTORC1 or RPS6 kinases warrants further investigation as potential therapeutic strategies for patients.
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Affiliation(s)
- Kali A Smolen
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Cinta M Papke
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Mark R Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Chenchen Li
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - E Alan Salter
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Ashley D Camp
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Richard E Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA.
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA; Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA.
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11
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Nadel G, Maik-Rachline G, Seger R. JNK Cascade-Induced Apoptosis-A Unique Role in GqPCR Signaling. Int J Mol Sci 2023; 24:13527. [PMID: 37686335 PMCID: PMC10487481 DOI: 10.3390/ijms241713527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 09/10/2023] Open
Abstract
The response of cells to extracellular signals is mediated by a variety of intracellular signaling pathways that determine stimulus-dependent cell fates. One such pathway is the cJun-N-terminal Kinase (JNK) cascade, which is mainly involved in stress-related processes. The cascade transmits its signals via a sequential activation of protein kinases, organized into three to five tiers. Proper regulation is essential for securing a proper cell fate after stimulation, and the mechanisms that regulate this cascade may involve the following: (1) Activatory or inhibitory phosphorylations, which induce or abolish signal transmission. (2) Regulatory dephosphorylation by various phosphatases. (3) Scaffold proteins that bring distinct components of the cascade in close proximity to each other. (4) Dynamic change of subcellular localization of the cascade's components. (5) Degradation of some of the components. In this review, we cover these regulatory mechanisms and emphasize the mechanism by which the JNK cascade transmits apoptotic signals. We also describe the newly discovered PP2A switch, which is an important mechanism for JNK activation that induces apoptosis downstream of the Gq protein coupled receptors. Since the JNK cascade is involved in many cellular processes that determine cell fate, addressing its regulatory mechanisms might reveal new ways to treat JNK-dependent pathologies.
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Affiliation(s)
| | | | - Rony Seger
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot 7610001, Israel; (G.N.); (G.M.-R.)
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12
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Guo Y, Zeng Q, Brooks D, Geisbrecht ER. A conserved STRIPAK complex is required for autophagy in muscle tissue. Mol Biol Cell 2023; 34:ar91. [PMID: 37379167 PMCID: PMC10398890 DOI: 10.1091/mbc.e23-01-0006] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 06/15/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023] Open
Abstract
Autophagy is important for cellular homeostasis and to prevent the abnormal accumulation of proteins. While many proteins that comprise the canonical autophagy pathway have been characterized, the identification of new regulators may help understand tissue and/or stress-specific responses. Using an in-silico approach, we identified Striatin interacting protein (Strip), MOB kinase activator 4, and fibroblast growth factor receptor 1 oncogene partner 2 as conserved mediators of muscle tissue maintenance. We performed affinity purification-mass spectrometry (AP-MS) experiments with Drosophila melanogaster Strip as a bait protein and copurified additional Striatin-interacting phosphatase and kinase (STRIPAK) complex members from larval muscle tissue. NUAK family kinase 1 (NUAK) and Starvin (Stv) also emerged as Strip-binding proteins and these physical interactions were verified in vivo using proximity ligation assays. To understand the functional significance of the STRIPAK-NUAK-Stv complex, we employed a sensitized genetic assay combined with RNA interference (RNAi) to demonstrate that both NUAK and stv function in the same biological process with genes that encode for STRIPAK complex proteins. RNAi-directed knockdown of Strip in muscle tissue led to the accumulation of ubiquitinated cargo, p62, and Autophagy-related 8a, consistent with a block in autophagy. Indeed, autophagic flux was decreased in Strip RNAi muscles, while lysosome biogenesis and activity were unaffected. Our results support a model whereby the STRIPAK-NUAK-Stv complex coordinately regulates autophagy in muscle tissue.
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Affiliation(s)
- Yungui Guo
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | - Qiling Zeng
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | - David Brooks
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | - Erika R. Geisbrecht
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
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13
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Guffens L, Derua R, Janssens V. PME-1 sensitizes glioblastoma cells to oxidative stress-induced cell death by attenuating PP2A-B55α-mediated inactivation of MAPKAPK2-RIPK1 signaling. Cell Death Discov 2023; 9:265. [PMID: 37500619 PMCID: PMC10374899 DOI: 10.1038/s41420-023-01572-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/13/2023] [Accepted: 07/20/2023] [Indexed: 07/29/2023] Open
Abstract
Glioblastoma (GBM) is the most common primary brain tumor in adults. Current standard therapy is surgery followed by radiotherapy, with concurrent and adjuvant temozolomide chemotherapy. GBM is characterized by almost uniformly fatal outcomes, highlighting the unmet clinical need for more efficient, biomarker-guided treatments. Protein phosphatase methylesterase-1 (PME-1), a regulator of the tumor suppressive phosphatase PP2A, promotes PP2A demethylation and inactivation, and is overexpressed in 44% of GBM, associated with increased tumor grade and cellular proliferation. Here, we aimed to investigate how reactive oxygen species (ROS), a frequent by-product of radiotherapy and temozolomide chemotherapy, regulate PP2A function via its methylesterase PME-1, and how PME-1 overexpression impacts the response of GBM cells to oxidative stress. We found that in two glioblastoma cell lines, U87MG and U251MG, expression of PME-1 is positively correlated with the sensitivity of the cells to H2O2 or t-BHP-induced oxidative stress. Experiments using the irreversible pharmacologic PME-1 inhibitor, AMZ30, and different PME-1 mutants, revealed that the methylesterase function, the PP2A binding capacity, and the nuclear localization of PME-1 are all important for the sensitizing effect of PME-1 expression. Furthermore, we identified increased nuclear localization of the PP2A-B55α subunit, increased binding of PP2A-B55α to PME-1, and increased B55α-bound PP2A-C demethylation upon oxidative stress. Lastly, we uncovered increased stress-induced phosphorylation and activity of MAPKAPK2 and RIPK1 in PME-1 overexpressing U87MG cells, which caused the observed sensitization to t-BHP treatment. Our data reveal a novel role for PME-1 in oxidative stress-induced GBM cell death, regulating nuclear PP2A-B55α activity and MAPKAPK2-RIPK1 signaling. Patients with GBM tumors overexpressing PME-1, although having a worse prognosis due to increased cellular proliferation of the tumor, could actually be more responsive to oxidative stress-inducing therapies.
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Affiliation(s)
- Liesbeth Guffens
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium
| | - Rita Derua
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium
- SyBioMa, KU Leuven, B-3000, Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium.
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium.
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Jiang TY, Cui XW, Zeng TM, Pan YF, Lin YK, Feng XF, Tan YX, Yuan ZG, Dong LW, Wang HY. PTEN deficiency facilitates gemcitabine efficacy in cancer by modulating the phosphorylation of PP2Ac and DCK. Sci Transl Med 2023; 15:eadd7464. [PMID: 37437018 DOI: 10.1126/scitranslmed.add7464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 06/22/2023] [Indexed: 07/14/2023]
Abstract
Gemcitabine is a nucleoside analog that has been successfully used in the treatment of multiple cancers. However, intrinsic or acquired resistance reduces the chemotherapeutic potential of gemcitabine. Here, we revealed a previously unappreciated mechanism by which phosphatase and tensin homolog (PTEN), one of the most frequently mutated genes in human cancers, dominates the decision-making process that is central to the regulation of gemcitabine efficacy in cholangiocarcinoma (CCA). By investigating a gemcitabine-treated CCA cohort, we found that PTEN deficiency was correlated with the improved efficacy of gemcitabine-based chemotherapy. Using cell-based drug sensitivity assays, cell line-derived xenograft, and patient-derived xenograft models, we further confirmed that PTEN deficiency or genetic-engineering down-regulation of PTEN facilitated gemcitabine efficacy both in vitro and in vivo. Mechanistically, PTEN directly binds to and dephosphorylates the C terminus of the catalytic subunit of protein phosphatase 2A (PP2Ac) to increase its enzymatic activity, which further dephosphorylates deoxycytidine kinase (DCK) at Ser74 to diminish gemcitabine efficacy. Therefore, PTEN deficiency and high phosphorylation of DCK predict a better response to gemcitabine-based chemotherapy in CCA. We speculate that the combination of PP2A inhibitor and gemcitabine in PTEN-positive tumors could avoid the resistance of gemcitabine, which would benefit a large population of patients with cancer receiving gemcitabine or other nucleoside analogs.
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Affiliation(s)
- Tian-Yi Jiang
- International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute, the Naval Medical University, Shanghai 200438, China
- National Center for Liver Cancer, the Naval Medical University, Shanghai 201805, China
| | - Xiao-Wen Cui
- National Center for Liver Cancer, the Naval Medical University, Shanghai 201805, China
- Department of Oncology, Eastern Hepatobiliary Surgery Hospital, the Naval Medical University, Shanghai 201805, China
| | - Tian-Mei Zeng
- Department of Oncology, Eastern Hepatobiliary Surgery Hospital, the Naval Medical University, Shanghai 201805, China
| | - Yu-Fei Pan
- International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute, the Naval Medical University, Shanghai 200438, China
- National Center for Liver Cancer, the Naval Medical University, Shanghai 201805, China
| | - Yun-Kai Lin
- International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute, the Naval Medical University, Shanghai 200438, China
- National Center for Liver Cancer, the Naval Medical University, Shanghai 201805, China
| | - Xiao-Fan Feng
- National Center for Liver Cancer, the Naval Medical University, Shanghai 201805, China
| | - Ye-Xiong Tan
- National Center for Liver Cancer, the Naval Medical University, Shanghai 201805, China
| | - Zhen-Gang Yuan
- Department of Oncology, Eastern Hepatobiliary Surgery Hospital, the Naval Medical University, Shanghai 201805, China
| | - Li-Wei Dong
- International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute, the Naval Medical University, Shanghai 200438, China
- National Center for Liver Cancer, the Naval Medical University, Shanghai 201805, China
| | - Hong-Yang Wang
- International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute, the Naval Medical University, Shanghai 200438, China
- National Center for Liver Cancer, the Naval Medical University, Shanghai 201805, China
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
- Shanghai Key Laboratory of Hepatobiliary Tumor Biology, Shanghai, 200438, China
- Laboratory of Signaling Regulation and Targeting Therapy of Liver Cancer, the Naval Medical University and Ministry of Education, Shanghai 200438, China
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15
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Kashif M, Alsaiari AA, Kumar B, Asalam M, Khan MI, Ahmad A, Lone RA, Almehmadi M, Zamzami MA, Akhtar MS. Recombinant expression and preliminary characterization of Peptidyl-prolyl cis/trans-isomerase Rrd1 from Saccharomyces cerevisiae. PLoS One 2023; 18:e0282749. [PMID: 37310980 DOI: 10.1371/journal.pone.0282749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/22/2023] [Indexed: 06/15/2023] Open
Abstract
Sacchromycescerevisiae Peptidyl-prolylcis/trans-isomerase Rrd1 has been linked to DNA repair, bud morphogenesis, advancement of the G1 phase, DNA replication stress, microtubule dynamics and is also necessary for the quick decrease in Sgs1p levels in response to rapamycin. In present study, Rrd1 gene was amplified by standard PCR and subsequently cloned downstream to bacteriophage T7 inducible promoter and lac operator of expression vector pET21d(+). Additionally, immobilized metal affinity chromatography (IMAC) was used to purify the protein upto its homogeneity, and its homogeneous purity was further confirmed through western blotting. Size exclusion chromatography implies that Rrd1 is existing as monomer in its natural state. Foldwise Rrd1 protein belongs to PTPA-like protein superfamily. Rrd1 showed characteristic negative minima at 222 and 208 nm represent protein typically acquired α helix in the far-UV CD spectra. Fluorescence spectra showed properly folded tertiary structures of Rrd1 at physiological conditions. Rrd1protein can be identified from different species using a fingerprint created by PIPSA analysis. The protein's abundance could aid in its crystallization, biophysical characterization and identification of other-interacting partners of Rrd1 protein.
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Affiliation(s)
- Mohd Kashif
- Center for Plant Molecular Biology and Biotechnology Division, CSIR-National Botanical Research Institute, Lucknow, Uttar Pradesh, India
| | - Ahad Amer Alsaiari
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, Taif, Saudi Arabia
| | - Bhupendra Kumar
- Center for Plant Molecular Biology and Biotechnology Division, CSIR-National Botanical Research Institute, Lucknow, Uttar Pradesh, India
| | - Mohd Asalam
- CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Lucknow, Uttar Pradesh, India
| | | | - Abrar Ahmad
- Department of Biochemistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Rayees Ahmad Lone
- Center for Plant Molecular Biology and Biotechnology Division, CSIR-National Botanical Research Institute, Lucknow, Uttar Pradesh, India
| | - Mazen Almehmadi
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, Taif, Saudi Arabia
| | - Mazin A Zamzami
- Department of Biochemistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mohd Sohail Akhtar
- CSIR-Central Drug Research Institute Sector 10, Jankipuram Extension, Lucknow, Uttar Pradesh, India
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16
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Patil RS, Kovacs-Kasa A, Gorshkov BA, Fulton DJR, Su Y, Batori RK, Verin AD. Serine/Threonine Protein Phosphatases 1 and 2A in Lung Endothelial Barrier Regulation. Biomedicines 2023; 11:1638. [PMID: 37371733 PMCID: PMC10296329 DOI: 10.3390/biomedicines11061638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/28/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Vascular barrier dysfunction is characterized by increased permeability and inflammation of endothelial cells (ECs), which are prominent features of acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and sepsis, and a major complication of the SARS-CoV-2 infection and COVID-19. Functional impairment of the EC barrier and accompanying inflammation arises due to microbial toxins and from white blood cells of the lung as part of a defensive action against pathogens, ischemia-reperfusion or blood product transfusions, and aspiration syndromes-based injury. A loss of barrier function results in the excessive movement of fluid and macromolecules from the vasculature into the interstitium and alveolae resulting in pulmonary edema and collapse of the architecture and function of the lungs, and eventually culminates in respiratory failure. Therefore, EC barrier integrity, which is heavily dependent on cytoskeletal elements (mainly actin filaments, microtubules (MTs), cell-matrix focal adhesions, and intercellular junctions) to maintain cellular contacts, is a critical requirement for the preservation of lung function. EC cytoskeletal remodeling is regulated, at least in part, by Ser/Thr phosphorylation/dephosphorylation of key cytoskeletal proteins. While a large body of literature describes the role of phosphorylation of cytoskeletal proteins on Ser/Thr residues in the context of EC barrier regulation, the role of Ser/Thr dephosphorylation catalyzed by Ser/Thr protein phosphatases (PPases) in EC barrier regulation is less documented. Ser/Thr PPases have been proposed to act as a counter-regulatory mechanism that preserves the EC barrier and opposes EC contraction. Despite the importance of PPases, our knowledge of the catalytic and regulatory subunits involved, as well as their cellular targets, is limited and under-appreciated. Therefore, the goal of this review is to discuss the role of Ser/Thr PPases in the regulation of lung EC cytoskeleton and permeability with special emphasis on the role of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) as major mammalian Ser/Thr PPases. Importantly, we integrate the role of PPases with the structural dynamics of the cytoskeleton and signaling cascades that regulate endothelial cell permeability and inflammation.
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Affiliation(s)
- Rahul S. Patil
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Anita Kovacs-Kasa
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Boris A. Gorshkov
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - David J. R. Fulton
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Yunchao Su
- Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Robert K. Batori
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Alexander D. Verin
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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17
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Zou W, Imperiale MJ. Regulation of Virus Replication by BK Polyomavirus Small T Antigen. J Virol 2023; 97:e0007723. [PMID: 36916919 PMCID: PMC10062181 DOI: 10.1128/jvi.00077-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/20/2023] [Indexed: 03/16/2023] Open
Abstract
Polyomavirus small T antigen (tAg) plays important roles in regulating viral replication, the innate immune response, apoptosis, and transformation for SV40, Merkel cell polyomavirus (MCPyV), murine polyomavirus (MuPyV), and JC polyomavirus (JCPyV). However, the function of BK polyomavirus (BKPyV) tAg has been much less studied. Here, we constructed mutant viruses that do not express tAg, and we showed that, in contrast with other polyomaviruses, BKPyV tAg inhibits large T antigen (TAg) gene expression and viral DNA replication. However, this occurs only in an archetype viral background. We also observed that the transduction of cells with a lentivirus-expressing BKPyV tAg kills the cells. We further discovered that BKPyV tAg interacts not only with PP2A A and C subunits, as has been demonstrated for other polyomavirus tAg proteins, but also with PP2A B''' subunit members. Knocking down either of two B''' subunits, namely STRN or STRN3, mimics the phenotype of the tAg mutant virus. However, a virus containing a point mutation in the PP2A binding domain of tAg only partially affected virus TAg expression and DNA replication. These results indicate that BKPyV tAg downregulates viral gene expression and DNA replication and that this occurs in part through interactions with PP2A. IMPORTANCE BK polyomavirus is a virus that establishes a lifelong infection of the majority of people. The infection usually does not cause any clinical symptoms, but, in transplant recipients whose immune systems have been suppressed, unchecked virus replication can cause severe disease. In this study, we show that a viral protein called small T antigen is one of the ways that the virus can persist without high levels of replication. Understanding which factors control viral replication enhances our knowledge of the virus life cycle and could lead to potential interventions for these patients.
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Affiliation(s)
- Wei Zou
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Michael J. Imperiale
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
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18
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KA S, CM P, Swingle MR, A M, C L, AD C, RE H, AN K. Quantitative proteomics and phosphoproteomics of PPP2R5D variants reveal deregulation of RPS6 phosphorylation through converging signaling cascades. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.27.534397. [PMID: 37034727 PMCID: PMC10081281 DOI: 10.1101/2023.03.27.534397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Variants in the phosphoprotein phosphatase-2 regulatory protein-5D gene ( PPP2R5D ) cause the clinical phenotype of Jordan's Syndrome (PPP2R5D-related disorder), which includes intellectual disability, hypotonia, seizures, macrocephaly, autism spectrum disorder and delayed motor skill development. The disorder originates from de novo single nucleotide mutations, generating missense variants that act in a dominant manner. Pathogenic mutations altering 13 different amino acids have been identified, with the E198K variant accounting for ∼40% of reported cases. Here, we use CRISPR-PRIME genomic editing to introduce a transition (c.592G>A) in the PPP2R5D allele in a heterozygous manner in HEK293 cells, generating E198K-heterozygous lines to complement existing E420K variant lines. We generate global protein and phosphorylation profiles of wild-type, E198K, and E420K cell lines and find unique and shared changes between variants and wild-type cells in kinase- and phosphatase-controlled signaling cascades. As shared signaling alterations, we observed ribosomal protein S6 (RPS6) hyperphosphorylation, indicative of increased ribosomal protein S6-kinase activity. Rapamycin treatment suppressed RPS6 phosphorylation in both, suggesting activation of mTORC1. Intriguingly, our data suggest AKT-dependent (E420K) and -independent (E198K) activation of mTORC1. Thus, although upstream activation of mTORC1 differs between PPP2R5D-related disorder genotypes, treatment with rapamycin or a p70S6K inhibitor warrants further investigation as potential therapeutic strategies for patients.
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Affiliation(s)
- Smolen KA
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Papke CM
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - MR Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Musiyenko A
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Li C
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Camp AD
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Honkanen RE
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Kettenbach AN
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
- Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
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19
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Welsh SA, Gardini A. Genomic regulation of transcription and RNA processing by the multitasking Integrator complex. Nat Rev Mol Cell Biol 2023; 24:204-220. [PMID: 36180603 PMCID: PMC9974566 DOI: 10.1038/s41580-022-00534-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2022] [Indexed: 11/09/2022]
Abstract
In higher eukaryotes, fine-tuned activation of protein-coding genes and many non-coding RNAs pivots around the regulated activity of RNA polymerase II (Pol II). The Integrator complex is the only Pol II-associated large multiprotein complex that is metazoan specific, and has therefore been understudied for years. Integrator comprises at least 14 subunits, which are grouped into distinct functional modules. The phosphodiesterase activity of the core catalytic module is co-transcriptionally directed against several RNA species, including long non-coding RNAs (lncRNAs), U small nuclear RNAs (U snRNAs), PIWI-interacting RNAs (piRNAs), enhancer RNAs and nascent pre-mRNAs. Processing of non-coding RNAs by Integrator is essential for their biogenesis, and at protein-coding genes, Integrator is a key modulator of Pol II promoter-proximal pausing and transcript elongation. Recent studies have identified an Integrator-specific serine/threonine-protein phosphatase 2A (PP2A) module, which targets Pol II and other components of the basal transcription machinery. In this Review, we discuss how the activity of Integrator regulates transcription, RNA processing, chromatin landscape and DNA repair. We also discuss the diverse roles of Integrator in development and tumorigenesis.
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de los Ríos C, Viejo L, Carretero VJ, Juárez NH, Cruz-Martins N, Hernández-Guijo JM. Promising Molecular Targets in Pharmacological Therapy for Neuronal Damage in Brain Injury. Antioxidants (Basel) 2023; 12:118. [PMID: 36670980 PMCID: PMC9854812 DOI: 10.3390/antiox12010118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/19/2022] [Accepted: 12/27/2022] [Indexed: 01/05/2023] Open
Abstract
The complex etiopathogenesis of brain injury associated with neurodegeneration has sparked a lot of studies in the last century. These clinical situations are incurable, and the currently available therapies merely act on symptoms or slow down the course of the diseases. Effective methods are being sought with an intent to modify the disease, directly acting on the properly studied targets, as well as to contribute to the development of effective therapeutic strategies, opening the possibility of refocusing on drug development for disease management. In this sense, this review discusses the available evidence for mitochondrial dysfunction induced by Ca2+ miscommunication in neurons, as well as how targeting phosphorylation events may be used to modulate protein phosphatase 2A (PP2A) activity in the treatment of neuronal damage. Ca2+ tends to be the catalyst for mitochondrial dysfunction, contributing to the synaptic deficiency seen in brain injury. Additionally, emerging data have shown that PP2A-activating drugs (PADs) suppress inflammatory responses by inhibiting different signaling pathways, indicating that PADs may be beneficial for the management of neuronal damage. In addition, a few bioactive compounds have also triggered the activation of PP2A-targeted drugs for this treatment, and clinical studies will help in the authentication of these compounds. If the safety profiles of PADs are proven to be satisfactory, there is a case to be made for starting clinical studies in the setting of neurological diseases as quickly as possible.
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Affiliation(s)
- Cristóbal de los Ríos
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
- Departamento de Ciencias Básicas de la Salud, University Rey Juan Carlos, Avda. Atenas s/n, 28922 Alcorcón, Spain
| | - Lucía Viejo
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Victoria Jiménez Carretero
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Natalia Hernández Juárez
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Natália Cruz-Martins
- Faculty of Medicine, Institute for Research and Innovation in Health (i3S), University of Porto, 4200-319 Porto, Portugal
- Institute for Research and Advanced Training in Health Sciences and Technologies, Rua Central de Gandra, 1317, 4585-116 Gandra, Portugal
| | - Jesús M. Hernández-Guijo
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
- Ramón y Cajal Institute for Health Research, IRYCIS, Hospital Ramón y Cajal, Ctra. de Colmenar Viejo, Km. 9,100, 28029 Madrid, Spain
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21
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Saini LK, Bheri M, Pandey GK. Protein phosphatases and their targets: Comprehending the interactions in plant signaling pathways. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 134:307-370. [PMID: 36858740 DOI: 10.1016/bs.apcsb.2022.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Protein phosphorylation is a vital reversible post-translational modification. This process is established by two classes of enzymes: protein kinases and protein phosphatases. Protein kinases phosphorylate proteins while protein phosphatases dephosphorylate phosphorylated proteins, thus, functioning as 'critical regulators' in signaling pathways. The eukaryotic protein phosphatases are classified as phosphoprotein phosphatases (PPP), metallo-dependent protein phosphatases (PPM), protein tyrosine (Tyr) phosphatases (PTP), and aspartate (Asp)-dependent phosphatases. The PPP and PPM families are serine (Ser)/threonine (Thr) specific phosphatases (STPs) that dephosphorylate Ser and Thr residues. The PTP family dephosphorylates Tyr residues while dual-specificity phosphatases (DsPTPs/DSPs) dephosphorylate Ser, Thr, and Tyr residues. The composition of these enzymes as well as their substrate specificity are important determinants of their functional significance in a number of cellular processes and stress responses. Their role in animal systems is well-understood and characterized. The functional characterization of protein phosphatases has been extensively covered in plants, although the comprehension of their mechanistic basis is an ongoing pursuit. The nature of their interactions with other key players in the signaling process is vital to our understanding. The substrates or targets determine their potential as well as magnitude of the impact they have on signaling pathways. In this article, we exclusively overview the various substrates of protein phosphatases in plant signaling pathways, which are a critical determinant of the outcome of various developmental and stress stimuli.
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Affiliation(s)
- Lokesh K Saini
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India
| | - Malathi Bheri
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India
| | - Girdhar K Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India.
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22
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The Dual Role of PDCD10 in Cancers: A Promising Therapeutic Target. Cancers (Basel) 2022; 14:cancers14235986. [PMID: 36497468 PMCID: PMC9740655 DOI: 10.3390/cancers14235986] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/28/2022] [Accepted: 12/01/2022] [Indexed: 12/11/2022] Open
Abstract
Programmed cell death 10 (PDCD10) was initially considered as a protein associated with apoptosis. However, recent studies showed that PDCD10 is actually an adaptor protein. By interacting with multiple molecules, PDCD10 participates in various physiological processes, such as cell survival, migration, cell differentiation, vesicle trafficking, cellular senescence, neurovascular development, and gonadogenesis. Moreover, over the past few decades, accumulating evidence has demonstrated that the aberrant expression or mutation of PDCD10 is extremely common in various pathological processes, especially in cancers. The dysfunction of PDCD10 has been strongly implicated in oncogenesis and tumor progression. However, the updated data seem to indicate that PDCD10 has a dual role (either pro- or anti-tumor effects) in various cancer types, depending on cell/tissue specificity with different cellular interactors. In this review, we aimed to summarize the knowledge of the dual role of PDCD10 in cancers with a special focus on its cellular function and potential molecular mechanism. With these efforts, we hoped to provide new insight into the future development and application of PDCD10 as a clinical therapeutic target in cancers.
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23
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Verbinnen I, Procknow SS, Lenaerts L, Reynhout S, Mehregan A, Ulens C, Janssens V, King KA. Clinical and molecular characteristics of a novel rare de novo variant in PPP2CA in a patient with a developmental disorder, autism, and epilepsy. Front Cell Dev Biol 2022; 10:1059938. [DOI: 10.3389/fcell.2022.1059938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 11/08/2022] [Indexed: 12/03/2022] Open
Abstract
PP2A-related (neuro) developmental disorders are a family of genetic diseases caused by a heterozygous alteration in one of several genes encoding a subunit of type 2A protein phosphatases. Reported affected genes, so far, are PPP2R5D, encoding the PP2A regulatory B56δ subunit; PPP2R1A, encoding the scaffolding Aα subunit; and PPP2CA, encoding the catalytic Cα subunit—in that order of frequency. Patients with a pathogenic de novo mutation in one of these genes, in part, present with overlapping features, such as generalized hypotonia, intellectual and developmental delay, facial dysmorphologies, seizures, and autistic features, and, in part, with opposite features, e.g., smaller versus larger head sizes or normal versus absent corpus callosum. Molecular variant characterization has been consistent so far with loss-of-function or dominant-negative disease mechanisms for all three affected genes. Here, we present a case report of another PPP2CA-affected individual with a novel de novo missense variant, resulting in a one-amino acid substitution in the Cα subunit: p.Cys196Arg. Biochemical characterization of the variant revealed its pathogenicity, as it appeared severely catalytically impaired, showed mildly affected A subunit binding, and moderately decreased binding to B/B55, B”/PR72, and all B56 subunits, except B56γ1. Carboxy-terminal methylation appeared unaffected, as was binding to B”’/STRN3—all being consistent with a partial loss of function. Clinically, the girl presented with mild-to-moderate developmental delay, a full-scale IQ of 83, mild dysmorphic facial features, tonic–clonic seizures, and autistic behaviors. Brain MRI appeared normal. We conclude that this individual falls within the milder end of the clinical and molecular spectrum of previously reported PPP2CA cases.
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24
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Tokunaga Y, Otsuyama KI, Kakuta S, Hayashida N. Heat Shock Transcription Factor 2 Is Significantly Involved in Neurodegenerative Diseases, Inflammatory Bowel Disease, Cancer, Male Infertility, and Fetal Alcohol Spectrum Disorder: The Novel Mechanisms of Several Severe Diseases. Int J Mol Sci 2022; 23:ijms232213763. [PMID: 36430241 PMCID: PMC9691173 DOI: 10.3390/ijms232213763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/03/2022] [Accepted: 11/05/2022] [Indexed: 11/10/2022] Open
Abstract
HSF (heat shock transcription factor or heat shock factor) was discovered as a transcription factor indispensable for heat shock response. Although four classical HSFs were discovered in mammals and two major HSFs, HSF1 and HSF2, were cloned in the same year of 1991, only HSF1 was intensively studied because HSF1 can give rise to heat shock response through the induction of various HSPs' expression. On the other hand, HSF2 was not well studied for some time, which was probably due to an underestimate of HSF2 itself. Since the beginning of the 21st century, HSF2 research has progressed and many biologically significant functions of HSF2 have been revealed. For example, the roles of HSF2 in nervous system protection, inflammation, maintenance of mitosis and meiosis, and cancer cell survival and death have been gradually unveiled. However, we feel that the fact HSF2 has a relationship with various factors is not yet widely recognized; therefore, the biological significance of HSF2 has been underestimated. We strongly hope to widely communicate the significance of HSF2 to researchers and readers in broad research fields through this review. In addition, we also hope that many readers will have great interest in the molecular mechanism in which HSF2 acts as an active transcription factor and gene bookmarking mechanism of HSF2 during cell cycle progression, as is summarized in this review.
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Affiliation(s)
- Yasuko Tokunaga
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Yamaguchi University, Yamaguchi 755-8505, Japan
- Institute of Gene Research, Yamaguchi University Science Research Center, Yamaguchi 755-8505, Japan
| | - Ken-Ichiro Otsuyama
- Department of Clinical Laboratory Science, Faculty of Health Science, Graduate School of Medicine, Yamaguchi University, Yamaguchi 755-8505, Japan
| | - Shigeru Kakuta
- Laboratory of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Naoki Hayashida
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Yamaguchi University, Yamaguchi 755-8505, Japan
- Correspondence: ; Tel.: +81-836-22-2359
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25
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Hali M, Wadzinski BE, Kowluru A. Alpha4 contributes to the dysfunction of the pancreatic beta cell under metabolic stress. Mol Cell Endocrinol 2022; 557:111754. [PMID: 35987388 PMCID: PMC9620510 DOI: 10.1016/j.mce.2022.111754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 08/10/2022] [Accepted: 08/12/2022] [Indexed: 11/30/2022]
Abstract
The current study examined the roles of Alpha4, a non-canonical subunit of protein phosphatase 2A, in the regulation of acute (insulin secretion) and chronic (cell dysfunction) effects of glucose in pancreatic beta cells. Alpha4 is expressed in human islets, rat islets and INS-1832/13 cells. Incubation of INS-1832/13 cells and rat islets with high glucose (HG) significantly increased the expression of Alpha4. C2-Ceramide, a biologically active sphingolipid, also increased the expression of Alpha4 in INS-1832/13 cells and rat islets. Subcellular distribution studies of Alpha4 in low glucose (LG) and HG exposed INS-1832/13 cells revealed that it is predominantly cytosolic, and its expression is significantly increased in the non-nuclear/cytosolic fractions in cells exposed to HG. siRNA-mediated knockdown of Alpha4 exerted minimal effects on glucose- or KCl-induced insulin secretion. siRNA-mediated deletion of Alpha4 significantly increased p38MAPK and JNK1/2 phosphorylation under LG conditions, comparable to the degree seen under HG conditions. Paradoxically, a significant potentiation of HG-induced p38MAPK and JNK2 phosphorylation was noted following Alpha4 deletion. HG-induced CHOP expression (ER stress marker) and caspase-3 activation were markedly attenuated in cells following Alpha4 knockdown. Deletion of Alpha4 in INS-1832/13 cells prevented HG-induced loss in the expression of Connexin36, a gap junction channel protein, which has been implicated in normal beta cell function. Lastly, depletion of endogenous Alpha4 significantly reduced HG-induced cell death in INS-1832/13 cells. Based on these findings we conclude that Alpha4 contributes to HG-induced metabolic dysfunction of the islet beta cell.
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Affiliation(s)
- Mirabela Hali
- Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, USA; Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
| | - Brian E Wadzinski
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, USA; Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA.
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Kashani E, Vassella E. Pleiotropy of PP2A Phosphatases in Cancer with a Focus on Glioblastoma IDH Wildtype. Cancers (Basel) 2022; 14:5227. [PMID: 36358647 PMCID: PMC9654311 DOI: 10.3390/cancers14215227] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/13/2022] [Accepted: 10/20/2022] [Indexed: 07/29/2023] Open
Abstract
Serine/Threonine protein phosphatase 2A (PP2A) is a heterotrimeric (or occasionally, heterodimeric) phosphatase with pleiotropic functions and ubiquitous expression. Despite the fact that they all contribute to protein dephosphorylation, multiple PP2A complexes exist which differ considerably by their subcellular localization and their substrate specificity, suggesting diverse PP2A functions. PP2A complex formation is tightly regulated by means of gene expression regulation by transcription factors, microRNAs, and post-translational modifications. Furthermore, a constant competition between PP2A regulatory subunits is taking place dynamically and depending on the spatiotemporal circumstance; many of the integral subunits can outcompete the rest, subjecting them to proteolysis. PP2A modulation is especially important in the context of brain tumors due to its ability to modulate distinct glioma-promoting signal transduction pathways, such as PI3K/Akt, Wnt, Ras, NF-κb, etc. Furthermore, PP2A is also implicated in DNA repair and survival pathways that are activated upon treatment of glioma cells with chemo-radiation. Depending on the cancer cell type, preclinical studies have shown some promise in utilising PP2A activator or PP2A inhibitors to overcome therapy resistance. This review has a special focus on "glioblastoma, IDH wild-type" (GBM) tumors, for which the therapy options have limited efficacy, and tumor relapse is inevitable.
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Affiliation(s)
- Elham Kashani
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Erik Vassella
- Institute of Pathology, University of Bern, 3008 Bern, Switzerland
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27
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Phosphatase protector alpha4 (α4) is involved in adipocyte maintenance and mitochondrial homeostasis through regulation of insulin signaling. Nat Commun 2022; 13:6092. [PMID: 36241662 PMCID: PMC9568526 DOI: 10.1038/s41467-022-33842-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 10/05/2022] [Indexed: 02/03/2023] Open
Abstract
Insulin signaling is mediated via a network of protein phosphorylation. Dysregulation of this network is central to obesity, type 2 diabetes and metabolic syndrome. Here we investigate the role of phosphatase binding protein Alpha4 (α4) that is essential for the serine/threonine protein phosphatase 2A (PP2A) in insulin action/resistance in adipocytes. Unexpectedly, adipocyte-specific inactivation of α4 impairs insulin-induced Akt-mediated serine/threonine phosphorylation despite a decrease in the protein phosphatase 2A (PP2A) levels. Interestingly, loss of α4 also reduces insulin-induced insulin receptor tyrosine phosphorylation. This occurs through decreased association of α4 with Y-box protein 1, resulting in the enhancement of the tyrosine phosphatase protein tyrosine phosphatase 1B (PTP1B) expression. Moreover, adipocyte-specific knockout of α4 in male mice results in impaired adipogenesis and altered mitochondrial oxidation leading to increased inflammation, systemic insulin resistance, hepatosteatosis, islet hyperplasia, and impaired thermogenesis. Thus, the α4 /Y-box protein 1(YBX1)-mediated pathway of insulin receptor signaling is involved in maintaining insulin sensitivity, normal adipose tissue homeostasis and systemic metabolism.
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28
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Guo Q, Wu G, Huang F, Wei Z, Wang JZ, Zhang B, Liu R, Yang Y, Wang X, Li HL. Novel small molecular compound 2JY-OBZ4 alleviates AD pathology in cell models via regulating multiple targets. Aging (Albany NY) 2022; 14:8077-8094. [PMID: 36227154 PMCID: PMC9596221 DOI: 10.18632/aging.204336] [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: 07/15/2022] [Accepted: 09/23/2022] [Indexed: 11/25/2022]
Abstract
Alzheimer’s disease (AD) is the most common form of neurodegenerative dementia, characterized by cognitive deficits and memory dysfunction, which is clinically incurable so far. Novel small molecular compound 2JY-OBZ4 is one of structural analogue of Huperzine A (Hup-A), an anti-AD drug in China. In our previous work, 2JY-OBZ4 exhibited potent effects on tau hyperphosphorylation, Aβ production and acetylcholinesterase (AChE) activity. However, 2JY-OBZ4's anti-AD effects and the underlying molecular mechanisms remain unclear. We here reported that 2JY-OBZ4 resisted tau hyperphosphorylation at Thr181 and Ser396 sites in HEK293-hTau cells transfected with GSK-3β, decreased tau phosphorylation via upregulating the activity of PP2A in HEK293-hTau cells and reduced Aβ production through regulating protein levels of APP cleavage enzymes in N2a-hAPP cells. Meanwhile, we found that 2JY-OBZ4 had no adverse effects on cell viability of mice primary neuron even at high concentration, and ameliorated synaptic loss induced by human oligomeric Aβ42. 2JY-OBZ4 had moderate AChE inhibitory activity with the half maximal inhibitory concentration (IC50) to be 39.48 μg/ml in vitro, which is more than two times higher than Hup-A. Together, 2JY-OBZ4 showed promising therapeutic effects in AD cell models through regulating multiple targets. The research provides a new candidate for the therapeutic development of AD.
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Affiliation(s)
- Qian Guo
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong JS 226001, China
| | - Gang Wu
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong JS 226001, China
| | - Fang Huang
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zhen Wei
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jian-Zhi Wang
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong JS 226001, China.,Institutes of Biomedical Sciences, School of Medicine, Jianghan University, Wuhan 430056, China
| | - Bin Zhang
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Rong Liu
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yang Yang
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xiaochuan Wang
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong JS 226001, China.,Institutes of Biomedical Sciences, School of Medicine, Jianghan University, Wuhan 430056, China.,Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen 518000, China
| | - Hong-Lian Li
- School of Basic Medicine, Key Laboratory of Education Ministry, Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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29
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Guo Q, Cai Q, Huang F, Wei Z, Wang JZ, Zhang B, Liu R, Yang Y, Wang X, Li HL. The Therapeutic Effects of Seven Lycophyte Compounds on Cell Models of Alzheimer’s Disease. J Alzheimers Dis 2022; 90:795-809. [DOI: 10.3233/jad-220704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background: As an acetylcholinesterase inhibitor (AChEI), Huperzine-A (Hup-A) is marketed for treatment of mild to moderate Alzheimer’s disease (AD) for decades in China. However, Hup-A causes some side effects. To search for new analogs or derivatives of Hup-A, we produced five Lycophyte alkaloids and two analogues by chemical synthesis: Lyconadins A-E, H-R-NOB, and 2JY-OBZ4. Objective: To systematically evaluated the therapeutic effects of the seven compounds on AD cell models. Methods: We assessed the effects of the seven compounds on cell viability via CCK-8 kit and used HEK293-hTau cells and N2a-hAPP cells as AD cell models to evaluate their potential therapeutic effects. We examined their effects on cholinesterase activity by employing the mice primary neuron. Results: All compounds did not affect cell viability; in addition, Lyconadin A and 2JY-OBZ4 particularly increased cell viability. Lyconadin D and Lyconadin E restored tau phosphorylation at Thr231, and H-R-NOB and 2JY-OBZ4 restored tau phosphorylation at Thr231 and Ser396 in GSK-3β-transfected HEK293-hTau cells. 2JY-OBZ4 decreased the level of PP2Ac-pY307 and increased the level of PP2Ac-mL309, supporting that 2JY-OBZ4 may activate PP2A. Lyconadin B, Lyconadin D, Lyconadin E, H-R-NOB, and 2JY-OBZ4 increased sAβPPα level in N2a-hAPP cells. 2JY-OBZ4 decreased the levels of BACE1 and sAβPPβ, thereby reduced Aβ production. Seven compounds exhibited weaker AChE activity inhibition efficiency than Hup-A. Among them, 2JY-OBZ4 showed the strongest AChE inhibition activity with an inhibition rate of 17% at 10μM. Conclusion: Among the seven lycophyte compounds, 2JY-OBZ4 showed the most expected effects on promoting cell viability, downregulating tau hyperphosphorylation, and Aβ production and inhibiting AChE in AD.
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Affiliation(s)
- Qian Guo
- School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan, China
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, JS, China
| | - Qinfeng Cai
- School of Mental Health and Psychological Science, Anhui Medical University, Hefei, Anhui, China
| | - Fang Huang
- School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan, China
| | - Zhen Wei
- School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan, China
| | - Jian-Zhi Wang
- School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan, China
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, JS, China
| | - Bin Zhang
- School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan, China
| | - Rong Liu
- School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan, China
| | - Yang Yang
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xiaochuan Wang
- School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan, China
- Co-innovation Center of Neuroregeneration, Nantong University, Nantong, JS, China
- Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen, China
| | - Hong-Lian Li
- School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Scienceand Technology, Wuhan, China
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30
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Deng DJ, Wang X, Yue KY, Wang Y, Jin QW. Analysis of the potential role of fission yeast PP2A in spindle assembly checkpoint inactivation. FASEB J 2022; 36:e22524. [PMID: 36006032 DOI: 10.1096/fj.202101884r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 07/26/2022] [Accepted: 08/17/2022] [Indexed: 11/11/2022]
Abstract
As a surveillance mechanism, the activated spindle assembly checkpoint (SAC) potently inhibits the E3 ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome) to ensure accurate chromosome segregation. Although the protein phosphatase 2A (PP2A) has been proposed to be both, directly and indirectly, involved in spindle assembly checkpoint inactivation in mammalian cells, whether it is similarly operating in the fission yeast Schizosaccharomycer pombe has never been demonstrated. Here, we investigated whether fission yeast PP2A is involved in SAC silencing by following the rate of cyclin B (Cdc13) destruction at SPBs during the recovery phase in nda3-KM311 cells released from the inhibition of APC/C by the activated spindle checkpoint. The timing of the SAC inactivation is only slightly delayed when two B56 regulatory subunits (Par1 and Par2) of fission yeast PP2A are absent. Overproduction of individual PP2A subunits either globally in the nda3-KM311 arrest-and-release system or locally in the synthetic spindle checkpoint activation system only slightly suppresses the SAC silencing defects in PP1 deletion (dis2Δ) cells. Our study thus demonstrates that the fission yeast PP2A is not a key regulator actively involved in SAC inactivation.
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Affiliation(s)
- Da-Jie Deng
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China
| | - Xi Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China
| | - Kai-Ye Yue
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China
| | - Yamei Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China
| | - Quan-Wen Jin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China
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Schuhmacher D, Sontag JM, Sontag E. A Novel Role of PP2A Methylation in the Regulation of Tight Junction Assembly and Integrity. Front Cell Dev Biol 2022; 10:911279. [PMID: 35912112 PMCID: PMC9326217 DOI: 10.3389/fcell.2022.911279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 06/21/2022] [Indexed: 12/04/2022] Open
Abstract
Tight junctions (TJs) are multiprotein complexes essential for cell polarity and the barrier function of epithelia. The major signaling molecule, protein serine/threonine phosphatase 2A (PP2A), interacts with the TJ and modulates the phosphorylation state of TJ proteins. An important PP2A regulatory mechanism involves leucine carboxyl methyltransferase-1 (LCMT1)-dependent methylation and protein phosphatase methylesterase-1 (PME1)-mediated demethylation of its catalytic subunit on Leu309. Here, using MDCK cells, we show that overexpression of LCMT1, which enhances cellular PP2A methylation, inhibits TJ formation, induces TJ ruffling, and decreases TJ barrier function. Conversely, overexpression of PME1 accelerates TJ assembly and enhances TJ barrier function. PME1-dependent PP2A demethylation increases during early Ca2+-dependent junctional assembly. Inhibition of endogenous PME1 delays the initial Ca2+-mediated redistribution of TJ proteins to cell-cell contacts and affects TJ morphology and barrier function. Manipulating one-carbon metabolism modulates TJ assembly, at least in part by affecting PP2A methylation state. The integrity of PP2A methylation is critical for proper targeting of PP2A to the TJ. It is necessary for PP2A complex formation with the TJ proteins, occludin and ZO-1, and proteins of the PAR complex, Par3 and atypical protein kinase C ζ (aPKCζ), which play a key role in development of cell polarity. Expression of a methylation incompetent PP2A mutant induces defects in TJ assembly and barrier function. aPKCζ-mediated Par3 phosphorylation is also required for targeting of the PP2A ABαC holoenzyme to the TJ. Our findings provide the first evidence for a role of LCMT1, PME1 and PP2A methylation/demethylation processes in modulating TJ assembly and functional integrity. They also position PP2A at the interface of one-carbon metabolism and the regulation of key TJ and polarity proteins that become deregulated in many human diseases.
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32
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Sontag JM, Schuhmacher D, Taleski G, Jordan A, Khan S, Hoffman A, Gomez RJ, Mazalouskas MD, Hanks SK, Spiller BW, Sontag E, Wadzinski BE. A new paradigm for regulation of protein phosphatase 2A function via Src and Fyn kinase-mediated tyrosine phosphorylation. J Biol Chem 2022; 298:102248. [PMID: 35820485 PMCID: PMC9396060 DOI: 10.1016/j.jbc.2022.102248] [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: 01/19/2022] [Revised: 07/01/2022] [Accepted: 07/04/2022] [Indexed: 12/01/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a major phospho-Ser/Thr phosphatase and a key regulator of cellular signal transduction pathways. While PP2A dysfunction has been linked to human cancer and neurodegenerative disorders such as Alzheimer’s disease (AD), PP2A regulation remains relatively poorly understood. It has been reported that the PP2A catalytic subunit (PP2Ac) is inactivated by a single phosphorylation at the Tyr307 residue by tyrosine kinases such as v-Src. However, multiple mass spectrometry studies have revealed the existence of other putative PP2Ac phosphorylation sites in response to activation of Src and Fyn, two major Src family kinases (SFKs). Here, using PP2Ac phosphomutants and novel phosphosite-specific PP2Ac antibodies, we show that cellular pools of PP2Ac are instead phosphorylated on both Tyr127 and Tyr284 upon Src activation, and on Tyr284 following Fyn activation. We found these phosphorylation events enhanced the interaction of PP2Ac with SFKs. In addition, we reveal SFK-mediated phosphorylation of PP2Ac at Y284 promotes dissociation of the regulatory Bα subunit, altering PP2A substrate specificity; the phosphodeficient Y127/284F and Y284F PP2Ac mutants prevented SFK-mediated phosphorylation of Tau at the CP13 (pSer202) epitope, a pathological hallmark of AD, and SFK-dependent activation of ERK, a major growth regulatory kinase upregulated in many cancers. Our findings demonstrate a novel PP2A regulatory mechanism that challenges the existing dogma on the inhibition of PP2A catalytic activity by Tyr307 phosphorylation. We propose dysregulation of SFK signaling in cancer and AD can lead to alterations in PP2A phosphorylation and subsequent deregulation of key PP2A substrates, including ERK and Tau.
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Affiliation(s)
- Jean-Marie Sontag
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Diana Schuhmacher
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Goce Taleski
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Anthony Jordan
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Sarah Khan
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Alexander Hoffman
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Rey J Gomez
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Matthew D Mazalouskas
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Steven K Hanks
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Benjamin W Spiller
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Estelle Sontag
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia.
| | - Brian E Wadzinski
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
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Hsieh CL, Yao Y, Gurevich VV, Chen J. Arrestin Facilitates Rhodopsin Dephosphorylation in Vivo. J Neurosci 2022; 42:3537-3545. [PMID: 35332081 PMCID: PMC9053844 DOI: 10.1523/jneurosci.0141-22.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/08/2022] [Accepted: 03/17/2022] [Indexed: 01/14/2023] Open
Abstract
Deactivation of G-protein-coupled receptors (GPCRs) involves multiple phosphorylations followed by arrestin binding, which uncouples the GPCR from G-protein activation. Some GPCRs, such as rhodopsin, are reused many times. Arrestin dissociation and GPCR dephosphorylation are key steps in the recycling process. In vitro evidence suggests that visual arrestin (ARR1) binding to light-activated, phosphorylated rhodopsin hinders dephosphorylation. Whether ARR1 binding also affects rhodopsin dephosphorylation in vivo is not known. We investigated this using both male and female mice lacking ARR1. Mice were exposed to bright light and placed in darkness for different periods of time, and differently phosphorylated species of rhodopsin were assayed by isoelectric focusing. For WT mice, rhodopsin dephosphorylation was nearly complete by 1 h in darkness. Surprisingly, we observed that, in the Arr1 KO rods, rhodopsin remained phosphorylated even after 3 h. Delayed dephosphorylation in Arr1 KO rods cannot be explained by cell stress induced by persistent signaling, since it is not prevented by the removal of transducin, the visual G-protein, nor can it be explained by downregulation of protein phosphatase 2A, the putative rhodopsin phosphatase. We further show that cone arrestin (ARR4), which binds light-activated, phosphorylated rhodopsin poorly, had little effect in enhancing rhodopsin dephosphorylation, whereas mice expressing binding-competent mutant ARR1-3A showed a similar time course of rhodopsin dephosphorylation as WT. Together, these results reveal a novel role of ARR1 in facilitating rhodopsin dephosphorylation in vivoSIGNIFICANCE STATEMENT G-protein-coupled receptors (GPCRs) are transmembrane proteins used by cells to receive and respond to a broad range of extracellular signals that include neurotransmitters, hormones, odorants, and light (photons). GPCR signaling is terminated by two sequential steps: phosphorylation and arrestin binding. Both steps must be reversed when GPCRs are recycled and reused. Dephosphorylation, which is required for recycling, is an understudied process. Using rhodopsin as a prototypical GPCR, we discovered that arrestin facilitated rhodopsin dephosphorylation in living mice.
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Affiliation(s)
- Chia-Ling Hsieh
- Ziliha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California 90089
| | - Yun Yao
- Ziliha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California 90089
| | - Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232
| | - Jeannie Chen
- Ziliha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California 90089
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Mahamane Salissou MT, Razak MYA, Wang X, Magaji RA. The role of protein phosphatase 2A tau axis in traumatic brain injury therapy. BENI-SUEF UNIVERSITY JOURNAL OF BASIC AND APPLIED SCIENCES 2022. [DOI: 10.1186/s43088-022-00223-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Traumatic brain injury (TBI) is a debilitating disorder due to trauma caused by an external mechanical force eventually leading to disruption in the normal function of the brain, with possible outcomes including permanent or temporary dysfunction of cognitive, physical, and psychosocial abilities. There have been several studies focusing on the search and innovation of neuroprotective agents that could have therapeutic relevance in TBI management. Due to its complexity, TBI is divided into two major components. The first initial event is known as the primary injury; it is a result of the mechanical insult itself and is known to be irreversible and resistant to a vast variety of therapeutics. The secondary event or secondary brain injury is viewed as a cellular injury that does not manifest immediately after the trauma but evolved after a delay period of hours or several days. This category of injury is known to respond favorably to different pharmacological treatment approaches.
Main body
Due to the complexity in the pathophysiology of the secondary injury, the therapeutic strategy needs to be in a multi-facets model and to have the ability to simultaneously regulate different cellular changes. Several studies have investigated in deep the possible approaches relying on natural compounds as an alternative therapeutic strategy for the management of TBI. In addition, many natural compounds have the potential to target numerous different components of the secondary injury including neuroinflammation, apoptosis, PP2A, tau, and Aβ among others. Here, we review past and current strategies in the therapeutic management of TBI, focusing on the PP2A-tau axis both in animal and human subjects. This review uncovers, in addition, a variety of compounds used in TBI therapy.
Conclusion
Despite beneficial therapeutic effects observed in animals for many compounds, studies are still needed to be conducted on human subjects to validate their therapeutic virtues. Furthermore, potential therapeutic virtues observed among studies might likely be dependent on the TBI animal model used and the type of induced injury. In addition, specificity and side effects are challenges in TBI therapy specifically which site of PP2A dysfunction to be targeted.
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35
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Nadel G, Yao Z, Wainstein E, Cohen I, Ben-Ami I, Schajnovitz A, Maik-Rachline G, Naor Z, Horwitz BA, Seger R. GqPCR-stimulated dephosphorylation of AKT is induced by an IGBP1-mediated PP2A switch. Cell Commun Signal 2022; 20:5. [PMID: 34998390 PMCID: PMC8742922 DOI: 10.1186/s12964-021-00805-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/18/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND G protein-coupled receptors (GPCRs) usually regulate cellular processes via activation of intracellular signaling pathways. However, we have previously shown that in several cell lines, GqPCRs induce immediate inactivation of the AKT pathway, which leads to JNK-dependent apoptosis. This apoptosis-inducing AKT inactivation is essential for physiological functions of several GqPCRs, including those for PGF2α and GnRH. METHODS Here we used kinase activity assays of PI3K and followed phosphorylation state of proteins using specific antibodies. In addition, we used coimmunoprecipitation and proximity ligation assays to follow protein-protein interactions. Apoptosis was detected by TUNEL assay and PARP1 cleavage. RESULTS We identified the mechanism that allows the unique stimulated inactivation of AKT and show that the main regulator of this process is the phosphatase PP2A, operating with the non-canonical regulatory subunit IGBP1. In resting cells, an IGBP1-PP2Ac dimer binds to PI3K, dephosphorylates the inhibitory pSer608-p85 of PI3K and thus maintains its high basal activity. Upon GqPCR activation, the PP2Ac-IGBP1 dimer detaches from PI3K and thus allows the inhibitory dephosphorylation. At this stage, the free PP2Ac together with IGBP1 and PP2Aa binds to AKT, causing its dephosphorylation and inactivation. CONCLUSION Our results show a stimulated shift of PP2Ac from PI3K to AKT termed "PP2A switch" that represses the PI3K/AKT pathway, providing a unique mechanism of GPCR-stimulated dephosphorylation. Video Abstract.
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Affiliation(s)
- Guy Nadel
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Zhong Yao
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Ehud Wainstein
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Izel Cohen
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Ido Ben-Ami
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel.,IVF and Fertility Unit, Department of OB/GYN, Shaare Zedek Medical Center and The Hebrew University Medical School, Jerusalem, Israel
| | - Amir Schajnovitz
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Galia Maik-Rachline
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel
| | - Zvi Naor
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel
| | - Benjamin A Horwitz
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel.,Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Rony Seger
- Departments of Biological Regulation, The Weizmann Institute of Science, Rehovot, Israel.
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Heo K, Basu H, Gutnick A, Wei W, Shlevkov E, Schwarz TL. Serine/Threonine Protein Phosphatase 2A Regulates the Transport of Axonal Mitochondria. Front Cell Neurosci 2022; 16:852245. [PMID: 35370563 PMCID: PMC8973303 DOI: 10.3389/fncel.2022.852245] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/14/2022] [Indexed: 11/13/2022] Open
Abstract
Microtubule-based transport provides mitochondria to distant regions of neurons and is essential for neuronal health. To identify compounds that increase mitochondrial motility, we screened 1,641 small-molecules in a high-throughput screening platform. Indirubin and cantharidin increased mitochondrial motility in rat cortical neurons. Cantharidin is known to inhibit protein phosphatase 2A (PP2A). We therefore tested two other inhibitors of PP2A: LB-100 and okadaic acid. LB-100 increased mitochondrial motility, but okadaic acid did not. To resolve this discrepancy, we knocked down expression of the catalytic subunit of PP2A (PP2CA). This long-term inhibition of PP2A more than doubled retrograde transport of axonal mitochondria, confirming the importance of PP2A as a regulator of mitochondrial motility and as the likely mediator of cantharidin's effect.
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Affiliation(s)
- Keunjung Heo
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States
| | - Himanish Basu
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States
| | - Amos Gutnick
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States
| | - Wei Wei
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States
| | - Evgeny Shlevkov
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States
| | - Thomas L Schwarz
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States
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37
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Sergienko NM, Donner DG, Delbridge LMD, McMullen JR, Weeks KL. Protein phosphatase 2A in the healthy and failing heart: New insights and therapeutic opportunities. Cell Signal 2021; 91:110213. [PMID: 34902541 DOI: 10.1016/j.cellsig.2021.110213] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 12/02/2021] [Accepted: 12/07/2021] [Indexed: 02/06/2023]
Abstract
Protein phosphatases have emerged as critical regulators of phosphoprotein homeostasis in settings of health and disease. Protein phosphatase 2A (PP2A) encompasses a large subfamily of enzymes that remove phosphate groups from serine/threonine residues within phosphoproteins. The heterogeneity in PP2A structure, which arises from the grouping of different catalytic, scaffolding and regulatory subunit isoforms, creates distinct populations of catalytically active enzymes (i.e. holoenzymes) that localise to different parts of the cell. This structural complexity, combined with other regulatory mechanisms, such as interaction of PP2A heterotrimers with accessory proteins and post-translational modification of the catalytic and/or regulatory subunits, enables PP2A holoenzymes to target phosphoprotein substrates in a highly specific manner. In this review, we summarise the roles of PP2A in cardiac physiology and disease. PP2A modulates numerous processes that are vital for heart function including calcium handling, contractility, β-adrenergic signalling, metabolism and transcription. Dysregulation of PP2A has been observed in human cardiac disease settings, including heart failure and atrial fibrillation. Efforts are underway, particularly in the cancer field, to develop therapeutics targeting PP2A activity. The development of small molecule activators of PP2A (SMAPs) and other compounds that selectively target specific PP2A holoenzymes (e.g. PP2A/B56α and PP2A/B56ε) will improve understanding of the function of different PP2A species in the heart, and may lead to the development of therapeutics for normalising aberrant protein phosphorylation in settings of cardiac remodelling and dysfunction.
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Affiliation(s)
- Nicola M Sergienko
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Central Clinical School, Monash University, Clayton VIC 3800, Australia
| | - Daniel G Donner
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia
| | - Lea M D Delbridge
- Department of Anatomy and Physiology, The University of Melbourne, Parkville VIC 3010, Australia
| | - Julie R McMullen
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia; Department of Physiology and Department of Medicine Alfred Hospital, Monash University, Clayton VIC 3800, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora VIC 3086, Australia; Department of Diabetes, Central Clinical School, Monash University, Clayton VIC 3800, Australia.
| | - Kate L Weeks
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Department of Anatomy and Physiology, The University of Melbourne, Parkville VIC 3010, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia; Department of Diabetes, Central Clinical School, Monash University, Clayton VIC 3800, Australia.
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38
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Pott J, Gadin J, Theusch E, Kleber ME, Delgado GE, Kirsten H, Hauck SM, Burkhardt R, Scharnagl H, Krauss RM, Loeffler M, März W, Thiery J, Silveira A, Vant Hooft FM, Scholz M. Meta-GWAS of PCSK9 levels detects two novel loci at APOB and TM6SF2. Hum Mol Genet 2021; 31:999-1011. [PMID: 34590679 PMCID: PMC8947322 DOI: 10.1093/hmg/ddab279] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 11/15/2022] Open
Abstract
Background Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key player in lipid metabolism, as it degrades low-density lipoprotein (LDL) receptors from hepatic cell membranes. So far, only variants of the PCSK9 gene locus were found to be associated with PCSK9 levels. Here we aimed to identify novel genetic loci that regulate PCSK9 levels and how they relate to other lipid traits. Additionally, we investigated to what extend the causal effect of PCSK9 on coronary artery disease (CAD) is mediated by low-density lipoprotein–cholesterol (LDL–C). Methods and Results We performed a genome-wide association study meta-analysis of PCSK9 levels in up to 12 721 samples of European ancestry. The estimated heritability was 10.3%, which increased to 12.6% using only samples from patients without statin treatment. We successfully replicated the known PCSK9 hit consisting of three independent signals. Interestingly, in a study of 300 African Americans, we confirmed the locus with a different PCSK9 variant. Beyond PCSK9, our meta-analysis detected three novel loci with genome-wide significance. Co-localization analysis with cis-eQTLs and lipid traits revealed biologically plausible candidate genes at two of them: APOB and TM6SF2. In a bivariate Mendelian Randomization analysis, we detected a strong effect of PCSK9 on LDL-C, but not vice versa. LDL-C mediated 63% of the total causal effect of PCSK9 on CAD. Conclusion Our study identified novel genetic loci with plausible candidate genes affecting PCSK9 levels. Ethnic heterogeneity was observed at the PCSK9 locus itself. Although the causal effect of PCSK9 on CAD is mainly mediated by LDL-C, an independent direct effect also occurs.
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Affiliation(s)
- Janne Pott
- Institute for Medical Informatics, Statistics and Epidemiology, Medical Faculty, University of Leipzig, Leipzig, Germany.,LIFE Research Center for Civilization Diseases, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Jesper Gadin
- Division of Cardiovascular Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Karolinska University Hospital Solna, Sweden
| | - Elizabeth Theusch
- Department of Pediatrics, University of California San Francisco, Oakland, CA, USA
| | - Marcus E Kleber
- Vth Department of Medicine (Nephrology, Hypertensiology, Rheumatology, Endocrinology, Diabetology), Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.,SYNLAB MVZ Humangenetik Mannheim, Mannheim, Germany
| | - Graciela E Delgado
- Vth Department of Medicine (Nephrology, Hypertensiology, Rheumatology, Endocrinology, Diabetology), Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Holger Kirsten
- Institute for Medical Informatics, Statistics and Epidemiology, Medical Faculty, University of Leipzig, Leipzig, Germany.,LIFE Research Center for Civilization Diseases, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Stefanie M Hauck
- Metabolomics and Proteomics Core and Research Unit Protein Science, Helmholtz Zentrum München, Neuherberg, Germany
| | - Ralph Burkhardt
- LIFE Research Center for Civilization Diseases, Medical Faculty, University of Leipzig, Leipzig, Germany.,Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig.,Institute of Clinical Chemistry and Laboratory Medicine, University Hospital Regensburg, Regensburg, Germany
| | - Hubert Scharnagl
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Ronald M Krauss
- Department of Pediatrics, University of California San Francisco, Oakland, CA, USA.,Department of Medicine, University of California San Francisco, Oakland, CA, USA
| | - Markus Loeffler
- Institute for Medical Informatics, Statistics and Epidemiology, Medical Faculty, University of Leipzig, Leipzig, Germany.,LIFE Research Center for Civilization Diseases, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Winfried März
- Vth Department of Medicine (Nephrology, Hypertensiology, Rheumatology, Endocrinology, Diabetology), Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.,Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria.,SYNLAB Academy, SYNALB Holding Deutschland GmbH, Mannheim, Germany
| | - Joachim Thiery
- LIFE Research Center for Civilization Diseases, Medical Faculty, University of Leipzig, Leipzig, Germany.,Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University Hospital Leipzig.,Faculty of Medicine, Kiel University, Kiel, Germany
| | - Angela Silveira
- Division of Cardiovascular Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Karolinska University Hospital Solna, Sweden
| | - Ferdinand M Vant Hooft
- Division of Cardiovascular Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Karolinska University Hospital Solna, Sweden
| | - Markus Scholz
- Institute for Medical Informatics, Statistics and Epidemiology, Medical Faculty, University of Leipzig, Leipzig, Germany.,LIFE Research Center for Civilization Diseases, Medical Faculty, University of Leipzig, Leipzig, Germany
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39
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Chu H, Sacharidou A, Nguyen A, Li C, Chambliss KL, Salmon JE, Shen YM, Lo J, Leone GW, Herz J, Hui DY, Marciano DK, Abrahams VM, Natale BV, Montalbano AP, Xiao X, Xu L, Natale DR, Shaul PW, Mineo C. Protein Phosphatase 2A Activation Via ApoER2 in Trophoblasts Drives Preeclampsia in a Mouse Model of the Antiphospholipid Syndrome. Circ Res 2021; 129:735-750. [PMID: 34404233 DOI: 10.1161/circresaha.120.318941] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
[Figure: see text].
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Affiliation(s)
- Haiyan Chu
- Center for Pulmonary and Vascular Biology, Pediatrics (H.C., A.S., A.N., C.L., K.L.C., P.W.S., C.M.)
| | - Anastasia Sacharidou
- Center for Pulmonary and Vascular Biology, Pediatrics (H.C., A.S., A.N., C.L., K.L.C., P.W.S., C.M.)
| | - An Nguyen
- Center for Pulmonary and Vascular Biology, Pediatrics (H.C., A.S., A.N., C.L., K.L.C., P.W.S., C.M.)
| | - Chun Li
- Center for Pulmonary and Vascular Biology, Pediatrics (H.C., A.S., A.N., C.L., K.L.C., P.W.S., C.M.)
| | - Ken L Chambliss
- Center for Pulmonary and Vascular Biology, Pediatrics (H.C., A.S., A.N., C.L., K.L.C., P.W.S., C.M.)
| | - Jane E Salmon
- Medicine, Hospital for Special Surgery, Weill Cornell Medical College, New York (J.E.S.)
| | - Yu-Min Shen
- Internal Medicine (Y.-M.S., D.K.M.), University of Texas Southwestern Medical Center, Dallas
| | - Julie Lo
- Obstetrics and Gynecology (J.L.), University of Texas Southwestern Medical Center, Dallas
| | - Gustavo W Leone
- Froedtert-Medical College of Wisconsin Cancer Center, Medical College of Wisconsin, Milwaukee (G.W.L.)
| | - Joachim Herz
- Molecular Genetics (J.H.), University of Texas Southwestern Medical Center, Dallas
| | - David Y Hui
- Pathology, University of Cincinnati College of Medicine (D.Y.H.)
| | - Denise K Marciano
- Internal Medicine (Y.-M.S., D.K.M.), University of Texas Southwestern Medical Center, Dallas.,Cell Biology (D.K.M., C.M.), University of Texas Southwestern Medical Center, Dallas
| | - Vikki M Abrahams
- Obstetrics, Gynecology & Reproductive Sciences, Yale School of Medicine, New Haven, CT (V.M.A.)
| | - Bryony V Natale
- Obstetrics, Gynecology & Reproductive Science, University of California San Diego, La Jolla (B.V.N., D.R.N.).,Obstetrics and Gynaecology, School of Medicine, Queen's University, Ontario, Canada (B.V.N., D.R.N.)
| | - Alina P Montalbano
- Biochemistry and Obstetrics and Gynecology (A.P.M.), University of Texas Southwestern Medical Center, Dallas
| | - Xue Xiao
- Population and Data Sciences and Pediatrics (X.X., L.X.), University of Texas Southwestern Medical Center, Dallas
| | - Lin Xu
- Population and Data Sciences and Pediatrics (X.X., L.X.), University of Texas Southwestern Medical Center, Dallas
| | - David R Natale
- Obstetrics, Gynecology & Reproductive Science, University of California San Diego, La Jolla (B.V.N., D.R.N.).,Obstetrics and Gynaecology, School of Medicine, Queen's University, Ontario, Canada (B.V.N., D.R.N.)
| | - Philip W Shaul
- Center for Pulmonary and Vascular Biology, Pediatrics (H.C., A.S., A.N., C.L., K.L.C., P.W.S., C.M.)
| | - Chieko Mineo
- Center for Pulmonary and Vascular Biology, Pediatrics (H.C., A.S., A.N., C.L., K.L.C., P.W.S., C.M.).,Cell Biology (D.K.M., C.M.), University of Texas Southwestern Medical Center, Dallas
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40
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Li H, Zhou Y, Wang M, Wang H, Zhang Y, Peng R, Zhang R, Zhang M, Zhang M, Qiu P, Liu L, Zhao Q, Liu J. DOC-2/DAB2 interactive protein destabilizes c-Myc to impair the growth and self-renewal of colon tumor-repopulating cells. Cancer Sci 2021; 112:4593-4603. [PMID: 34449943 PMCID: PMC8586666 DOI: 10.1111/cas.15120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 08/21/2021] [Accepted: 08/25/2021] [Indexed: 02/06/2023] Open
Abstract
Colorectal carcinoma (CRC) remains a huge challenge in clinical treatment due to tumor metastasis and recurrence. Stem cell-like colon tumor-repopulating cells (TRCs) are a subpopulation of cancer cells with highly tumorigenic and chemotherapy resistant properties. The core transcription factor c-Myc is essential for maintaining cancer stem-like cell phenotypes, yet its roles and regulatory mechanisms remain unclear in colon TRCs. We report that elevated c-Myc protein supported formation and growth of TRC spheroids. The tumor suppressor DOC-2/DAB2 interactive protein (DAB2IP) suppressed c-Myc expression to inhibit TRC expansion and self-renewal. Particularly, DAB2IP disrupted c-Myc stability through glycogen synthase kinase 3β/protein phosphatase 2A-B56α-mediated phosphorylation and dephosphorylation cascade on c-Myc protein, leading to its eventual degradation through the ubiquitin-proteasome pathway. The expression of DAB2IP was negatively correlated with c-Myc in CRC specimens. Overall, our results improved mechanistic insight into how DAB2IP suppressed TRC growth and self-renewal.
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Affiliation(s)
- Haiou Li
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Yunjiao Zhou
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Meng Wang
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Haizhou Wang
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Yangyang Zhang
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Ruyi Peng
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Ruike Zhang
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Meng Zhang
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Mengna Zhang
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Peishan Qiu
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Lan Liu
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Qiu Zhao
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
| | - Jing Liu
- Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
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41
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Protein Phosphatase 2A (PP2A) mutations in brain function, development, and neurologic disease. Biochem Soc Trans 2021; 49:1567-1588. [PMID: 34241636 DOI: 10.1042/bst20201313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/09/2021] [Accepted: 06/11/2021] [Indexed: 12/15/2022]
Abstract
By removing Ser/Thr-specific phosphorylations in a multitude of protein substrates in diverse tissues, Protein Phosphatase type 2A (PP2A) enzymes play essential regulatory roles in cellular signalling and physiology, including in brain function and development. Here, we review current knowledge on PP2A gene mutations causally involved in neurodevelopmental disorders and intellectual disability, focusing on PPP2CA, PPP2R1A and PPP2R5D. We provide insights into the impact of these mutations on PP2A structure, substrate specificity and potential function in neurobiology and brain development.
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42
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Sandal P, Jong CJ, Merrill RA, Song J, Strack S. Protein phosphatase 2A - structure, function and role in neurodevelopmental disorders. J Cell Sci 2021; 134:270819. [PMID: 34228795 DOI: 10.1242/jcs.248187] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Neurodevelopmental disorders (NDDs), including intellectual disability (ID), autism and schizophrenia, have high socioeconomic impact, yet poorly understood etiologies. A recent surge of large-scale genome or exome sequencing studies has identified a multitude of mostly de novo mutations in subunits of the protein phosphatase 2A (PP2A) holoenzyme that are strongly associated with NDDs. PP2A is responsible for at least 50% of total Ser/Thr dephosphorylation in most cell types and is predominantly found as trimeric holoenzymes composed of catalytic (C), scaffolding (A) and variable regulatory (B) subunits. PP2A can exist in nearly 100 different subunit combinations in mammalian cells, dictating distinct localizations, substrates and regulatory mechanisms. PP2A is well established as a regulator of cell division, growth, and differentiation, and the roles of PP2A in cancer and various neurodegenerative disorders, such as Alzheimer's disease, have been reviewed in detail. This Review summarizes and discusses recent reports on NDDs associated with mutations of PP2A subunits and PP2A-associated proteins. We also discuss the potential impact of these mutations on the structure and function of the PP2A holoenzymes and the etiology of NDDs.
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Affiliation(s)
- Priyanka Sandal
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Chian Ju Jong
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Jianing Song
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
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43
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Meeusen B, Cortesi EE, Domènech Omella J, Sablina A, Ventura JJ, Janssens V. PPP2R4 dysfunction promotes KRAS-mutant lung adenocarcinoma development and mediates opposite responses to MEK and mTOR inhibition. Cancer Lett 2021; 520:57-67. [PMID: 34216687 DOI: 10.1016/j.canlet.2021.06.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 06/21/2021] [Accepted: 06/24/2021] [Indexed: 12/30/2022]
Abstract
KRAS-mutant lung adenocarcinomas represent the largest molecular subgroup of non-small cell lung cancers (NSCLC) and are notorious for their dismal survival perspectives. To gain more insights in etiology and therapeutic response, we focused on the tumor suppressor Protein Phosphatase 2A (PP2A) as a player in KRAS oncogenic signaling. We report that the PP2A activator PTPA (encoded by PPP2R4) is commonly affected in NSCLC by heterozygous loss and low-frequent loss-of-function mutation, and this is specifically associated with poorer overall survival of KRAS-mutant lung adenocarcinoma patients. Reduced or mutant PPP2R4 expression in A549 cells increased anchorage-independent growth in vitro and xenograft growth in vivo, correlating with increased Ki67 and c-MYC expression. Moreover, KrasG12D-induced lung tumorigenesis was significantly accelerated in Ppp2r4 gene trapped mice as compared to Ppp2r4 wild-type. A confined kinase inhibitor screen revealed that PPP2R4-depletion induced resistance against selumetinib (MEK inhibitor), but unexpectedly sensitized cells for temsirolimus (mTOR inhibitor), in vitro and in vivo. Our findings underscore a clinically relevant role for PTPA loss-of-function in KRAS-mutant NSCLC etiology and kinase inhibitor response.
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Affiliation(s)
- Bob Meeusen
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium; KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium
| | - Emanuela Elsa Cortesi
- Translational Cell & Tissue Research, Dept. Imaging & Pathology, KU Leuven, B-3000, Leuven, Belgium
| | - Judit Domènech Omella
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium; KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium
| | - Anna Sablina
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium; Laboratory for Mechanisms of Cell Transformation, VIB Center for Cancer Biology & Dept. Oncology, KU Leuven, B-3000, Leuven, Belgium
| | - Juan-Jose Ventura
- Translational Cell & Tissue Research, Dept. Imaging & Pathology, KU Leuven, B-3000, Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium; KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium.
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44
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Ikeda S, Tsuji S, Ohama T, Sato K. Involvement of PP2A methylation in the adipogenic differentiation of bone marrow-derived mesenchymal stem cell. J Biochem 2021; 168:643-650. [PMID: 32663263 DOI: 10.1093/jb/mvaa077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 06/20/2020] [Accepted: 07/06/2020] [Indexed: 12/12/2022] Open
Abstract
Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stem cells with ability to self-replicate and differentiate into mesodermal derivatives, such as adipocytes and osteoblasts. BM-MSCs are a critical component of the tumour microenvironment. They support tumour progression by recruiting additional BM-MSCs and by differentiating into myofibroblasts (also called cancer-associated fibroblasts). Protein phosphatase 2A (PP2A) is an essential serine/threonine protein phosphatase that regulates a broad range of cellular signalling. PP2A forms a heterotrimer to dephosphorylate specific substrates. The reversible methylesterification (methylation) of Leu309 in the catalytic subunit of PP2A (PP2Ac) regulates biogenesis of the PP2A holoenzyme. It is unknown whether the methylation of PP2Ac plays a role in BM-MSC differentiation. Our experiments determined that protein levels of PP2A subunits and PP2A methyltransferase (LCMT-1) are significantly altered during differentiation. PP2Ac methylation levels in BM-MSCs decrease over time in response to an adipogenic differentiation stimulus. However, blockage of PP2A demethylation using the PP2A dimethyl-esterase inhibitors enhanced adipocyte differentiation. This suggests that PP2Ac demethylation is involved in adipocyte differentiation resistance. The results of our study provide a greater understanding of the regulation of BM-MSCs differentiation by PP2A holoenzyme.
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Affiliation(s)
- Shunta Ikeda
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Shunya Tsuji
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Takashi Ohama
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Koichi Sato
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
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45
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Rathor N, Chung HK, Song JL, Wang SR, Wang JY, Rao JN. TRPC1-mediated Ca 2+ signaling enhances intestinal epithelial restitution by increasing α4 association with PP2Ac after wounding. Physiol Rep 2021; 9:e14864. [PMID: 33991460 PMCID: PMC8123541 DOI: 10.14814/phy2.14864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/02/2021] [Accepted: 01/13/2021] [Indexed: 11/24/2022] Open
Abstract
Gut epithelial restitution after superficial wounding is an important repair modality regulated by numerous factors including Ca2+ signaling and cellular polyamines. Transient receptor potential canonical-1 (TRPC1) functions as a store-operated Ca2+ channel in intestinal epithelial cells (IECs) and its activation increases epithelial restitution by inducing Ca2+ influx after acute injury. α4 is a multiple functional protein and implicated in many aspects of cell functions by modulating protein phosphatase 2A (PP2A) stability and activity. Here we show that the clonal populations of IECs stably expressing TRPC1 (IEC-TRPC1) exhibited increased levels of α4 and PP2A catalytic subunit (PP2Ac) and that TRPC1 promoted intestinal epithelial restitution by increasing α4/PP2Ac association. The levels of α4 and PP2Ac proteins increased significantly in stable IEC-TRPC1 cells and this induction in α4/PP2Ac complexes was accompanied by an increase in IEC migration after wounding. α4 silencing by transfection with siRNA targeting α4 (siα4) or PP2Ac silencing destabilized α4/PP2Ac complexes in stable IEC-TRPC1 cells and repressed cell migration over the wounded area. Increasing the levels of cellular polyamines by stable transfection with the Odc gene stimulated α4 and PP2Ac expression and enhanced their association, thus also promoting epithelial restitution after wounding. In contrast, depletion of cellular polyamines by treatment with α-difluoromethylornithine reduced α4/PP2Ac complexes and repressed cell migration. Ectopic overexpression of α4 partially rescued rapid epithelial repair in polyamine-deficient cells. These results indicate that activation of TRPC1-mediated Ca2+ signaling enhances cell migration primarily by increasing α4/PP2Ac associations after wounding and this pathway is tightly regulated by cellular polyamines.
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Affiliation(s)
- Navneeta Rathor
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.,Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA
| | - Hee Kyoung Chung
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.,Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA
| | - Jia-Le Song
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shelley R Wang
- Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA
| | - Jian-Ying Wang
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.,Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA.,Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jaladanki N Rao
- Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.,Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA
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46
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Khayachi A, Schorova L, Alda M, Rouleau GA, Milnerwood AJ. Posttranslational modifications & lithium's therapeutic effect-Potential biomarkers for clinical responses in psychiatric & neurodegenerative disorders. Neurosci Biobehav Rev 2021; 127:424-445. [PMID: 33971223 DOI: 10.1016/j.neubiorev.2021.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 03/14/2021] [Accepted: 05/03/2021] [Indexed: 01/03/2023]
Abstract
Several neurodegenerative diseases and neuropsychiatric disorders display aberrant posttranslational modifications (PTMs) of one, or many, proteins. Lithium treatment has been used for mood stabilization for many decades, and is highly effective for large subsets of patients with diverse neurological conditions. However, the differential effectiveness and mode of action are not fully understood. In recent years, studies have shown that lithium alters several protein PTMs, altering their function, and consequently neuronal physiology. The impetus for this review is to outline the links between lithium's therapeutic mode of action and PTM homeostasis. We first provide an overview of the principal PTMs affected by lithium. We then describe several neuropsychiatric disorders in which PTMs have been implicated as pathogenic. For each of these conditions, we discuss lithium's clinical use and explore the putative mechanism of how it restores PTM homeostasis, and thereby cellular physiology. Evidence suggests that determining specific PTM patterns could be a promising strategy to develop biomarkers for disease and lithium responsiveness.
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Affiliation(s)
- A Khayachi
- Montreal Neurological Institute, Department of Neurology & Neurosurgery, McGill University, Montréal, Quebec, Canada.
| | - L Schorova
- McGill University Health Center Research Institute, Montréal, Quebec, Canada
| | - M Alda
- Department of Psychiatry, Dalhousie University, Halifax, Nova Scotia, Canada
| | - G A Rouleau
- Montreal Neurological Institute, Department of Neurology & Neurosurgery, McGill University, Montréal, Quebec, Canada; Department of Human Genetics, McGill University, Montréal, Quebec, Canada.
| | - A J Milnerwood
- Montreal Neurological Institute, Department of Neurology & Neurosurgery, McGill University, Montréal, Quebec, Canada.
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47
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Frohner IE, Mudrak I, Schüchner S, Anrather D, Hartl M, Sontag JM, Sontag E, Wadzinski BE, Preglej T, Ellmeier W, Ogris E. PP2A C Phospho-Tyr 307 Antibodies Are Not Specific for this Modification but Are Sensitive to Other PP2A C Modifications Including Leu 309 Methylation. Cell Rep 2021; 30:3171-3182.e6. [PMID: 32130916 DOI: 10.1016/j.celrep.2020.02.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/03/2019] [Accepted: 02/07/2020] [Indexed: 02/06/2023] Open
Abstract
Protein phosphatase 2A (PP2A) is an important regulator of signal transduction pathways and a tumor suppressor. Phosphorylation of the PP2A catalytic subunit (PP2AC) at tyrosine 307 has been claimed to inactivate PP2A and was examined in more than 180 studies using commercial antibodies, but this modification was never identified using mass spectrometry. Here we show that the most cited pTyr307 monoclonal antibodies, E155 and F-8, are not specific for phosphorylated Tyr307 but instead are hampered by PP2AC methylation at leucine 309 or phosphorylation at threonine 304. Other pTyr307 antibodies are sensitive to PP2AC methylation as well, and some cross-react with pTyr residues in general, including phosphorylated hemagglutinin tags. We identify pTyr307 using targeted mass spectrometry after transient overexpression of PP2AC and Src kinase. Yet under such conditions, none of the tested antibodies show exclusive pTyr307 specificity. Thus, data generated using these antibodies need to be revisited, and the mechanism of PP2A inactivation needs to be redefined.
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Affiliation(s)
- Ingrid E Frohner
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Ingrid Mudrak
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Stefan Schüchner
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Dorothea Anrather
- Mass Spectrometry Facility, Max Perutz Labs, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Markus Hartl
- Mass Spectrometry Facility, Max Perutz Labs, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Jean-Marie Sontag
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Estelle Sontag
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Brian E Wadzinski
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Teresa Preglej
- Division of Immunobiology, Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Wilfried Ellmeier
- Division of Immunobiology, Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria
| | - Egon Ogris
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
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48
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Gnanaprakash M, Staniszewski A, Zhang H, Pitstick R, Kavanaugh MP, Arancio O, Nicholls RE. Leucine Carboxyl Methyltransferase 1 Overexpression Protects Against Cognitive and Electrophysiological Impairments in Tg2576 APP Transgenic Mice. J Alzheimers Dis 2021; 79:1813-1829. [PMID: 33459709 PMCID: PMC8203222 DOI: 10.3233/jad-200462] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background: The serine/threonine protein phosphatase, PP2A, is thought to play a central role in the molecular pathogenesis of Alzheimer’s disease (AD), and the activity and substrate specificity of PP2A is regulated, in part, through methylation and demethylation of its catalytic subunit. Previously, we found that transgenic overexpression of the PP2A methyltransferase, LCMT-1, or the PP2A methylesterase, PME-1, altered the sensitivity of mice to impairments caused by acute exposure to synthetic oligomeric amyloid-β (Aβ). Objective: Here we sought to test the possibility that these molecules also controlled sensitivity to impairments caused by chronically elevated levels of Aβ produced in vivo. Methods: To do this, we examined the effects of transgenic LCMT-1, or PME-1 overexpression on cognitive and electrophysiological impairments caused by chronic overexpression of mutant human APP in Tg2576 mice. Results: We found that LCMT-1 overexpression prevented impairments in short-term spatial memory and synaptic plasticity in Tg2576 mice, without altering APP expression or soluble Aβ levels. While the magnitude of the effects of PME-1 overexpression in Tg2576 mice was small and potentially confounded by the emergence of non-cognitive impairments, Tg2576 mice that overexpressed PME-1 showed a trend toward earlier onset and/or increased severity of cognitive and electrophysiological impairments. Conclusion: These data suggest that the PP2A methyltransferase, LCMT-1, and the PP2A methylesterase, PME-1, may participate in the molecular pathogenesis of AD by regulating sensitivity to the pathogenic effects of chronically elevated levels of Aβ.
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Affiliation(s)
- Madhumathi Gnanaprakash
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
| | - Agnieszka Staniszewski
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
| | - Hong Zhang
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
| | | | | | - Ottavio Arancio
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA.,Department of Medicine, Columbia University, New York, NY, USA
| | - Russell E Nicholls
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
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49
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Bi X, Jiang B, Zhou J, Fan X, Yan X, Liang J, Luo L, Yin Z. CBP Bromodomain Inhibition Rescues Mice From Lethal Sepsis Through Blocking HMGB1-Mediated Inflammatory Responses. Front Immunol 2021; 11:625542. [PMID: 33603756 PMCID: PMC7884462 DOI: 10.3389/fimmu.2020.625542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 12/21/2020] [Indexed: 12/30/2022] Open
Abstract
CREB binding protein (CBP), a transcriptional coactivator and acetyltransferase, is involved in the pathogenesis of inflammation-related diseases. High mobility group box-1 protein (HMGB1) is a critical mediator of lethal sepsis, which has prompted investigation for the development of new treatment for inflammation. Here, we report that the potent and selective inhibition of CBP bromodomain by SGC-CBP30 blocks HMGB1-mediated inflammatory responses in vitro and in vivo. Our data suggest that CBP bromodomain inhibition suppresses LPS-induced expression and release of HMGB1, when the inhibitor was given 8 h post LPS stimulation; moreover, CBP bromodomain inhibition attenuated pro-inflammatory activity of HMGB1. Furthermore, our findings provide evidence that SGC-CBP30 down-regulated rhHMGB1-induced activation of MAPKs and NF-κB signaling by triggering the reactivation of protein phosphatase 2A (PP2A) and the stabilization of MAPK phosphatase 1 (MKP-1). Collectively, these results suggest that CBP bromodomain could serve as a candidate therapeutic target for the treatment of lethal sepsis via inhibiting LPS-induced expression and release of HMGB1 and suppressing the pro-inflammatory activity of HMGB1.
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Affiliation(s)
- Xiaowen Bi
- Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
| | - Baolin Jiang
- Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
| | - Jinyi Zhou
- Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
| | - Xirui Fan
- Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
| | - Xintong Yan
- Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
| | - Juanjuan Liang
- Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
| | - Lan Luo
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Zhimin Yin
- Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
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Ong JY, Bradley MC, Torres JZ. Phospho-regulation of mitotic spindle assembly. Cytoskeleton (Hoboken) 2020; 77:558-578. [PMID: 33280275 PMCID: PMC7898546 DOI: 10.1002/cm.21649] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/08/2020] [Accepted: 12/02/2020] [Indexed: 12/23/2022]
Abstract
The assembly of the bipolar mitotic spindle requires the careful orchestration of a myriad of enzyme activities like protein posttranslational modifications. Among these, phosphorylation has arisen as the principle mode for spatially and temporally activating the proteins involved in early mitotic spindle assembly processes. Here, we review key kinases, phosphatases, and phosphorylation events that regulate critical aspects of these processes. We highlight key phosphorylation substrates that are important for ensuring the fidelity of centriole duplication, centrosome maturation, and the establishment of the bipolar spindle. We also highlight techniques used to understand kinase-substrate relationships and to study phosphorylation events. We conclude with perspectives on the field of posttranslational modifications in early mitotic spindle assembly.
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Affiliation(s)
- Joseph Y Ong
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA
| | - Michelle C Bradley
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA
| | - Jorge Z Torres
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA.,Molecular Biology Institute, University of California, Los Angeles, California, USA.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California, USA
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