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Zhao L, Liu J, Li K, Zhang C, Chen T, Liu Z, Tang Y, Hu X, Shi A, Shu L, Huang S, Lian S, Zhang M, Li H, Sun J, Yu X, Zhang Z, Zhang Z, Xu Y. PTPN9 dephosphorylates FGFR2 pY656/657 through interaction with ACAP1 and ameliorates pemigatinib effect in cholangiocarcinoma. Hepatology 2024; 79:798-812. [PMID: 37505213 DOI: 10.1097/hep.0000000000000552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/06/2023] [Indexed: 07/29/2023]
Abstract
ABSTRACT AND AIM Cholangiocarcinoma (CCA) is a highly aggressive and lethal cancer that originates from the biliary epithelium. Systemic treatment options for CCA are currently limited, and the first targeted drug of CCA, pemigatinib, emerged in 2020 for CCA treatment by inhibiting FGFR2 phosphorylation. However, the regulatory mechanism of FGFR2 phosphorylation is not fully elucidated. APPROACH AND RESULTS Here we screened the FGFR2-interacting proteins and showed that protein tyrosine phosphatase (PTP) N9 interacts with FGFR2 and negatively regulates FGFR2 pY656/657 . Using phosphatase activity assays and modeling the FGFR2-PTPN9 complex structure, we identified FGFR2 pY656/657 as a substrate of PTPN9, and found that sec. 14p domain of PTPN9 interacts with FGFR2 through ACAP1 mediation. Coexpression of PTPN9 and ACAP1 indicates a favorable prognosis for CCA. In addition, we identified key amino acids and motifs involved in the sec. 14p-APCP1-FGFR2 interaction, including the "YRETRRKE" motif of sec. 14p, Y471 of PTPN9, as well as the PH and Arf-GAP domain of ACAP1. Moreover, we discovered that the FGFR2 I654V substitution can decrease PTPN9-FGFR2 interaction and thereby reduce the effectiveness of pemigatinib treatment. Using a series of in vitro and in vivo experiments including patient-derived xenografts (PDX), we showed that PTPN9 synergistically enhances pemigatinib effectiveness and suppresses CCA proliferation, migration, and invasion by inhibiting FGFR2 pY656/657 . CONCLUSIONS Our study identifies PTPN9 as a negative regulator of FGFR2 phosphorylation and a synergistic factor for pemigatinib treatment. The molecular mechanism, oncogenic function, and clinical significance of the PTPN9-ACAP1-FGFR2 complex are revealed, providing more evidence for CCA precision treatment.
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Affiliation(s)
- Liming Zhao
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Jialiang Liu
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Kangshuai Li
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Chao Zhang
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Tianli Chen
- Department of Colorectal Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Zengli Liu
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Yongchang Tang
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Xiaoqiang Hu
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Anda Shi
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Lizhuang Shu
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Shaohui Huang
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Shuo Lian
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Minghui Zhang
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Hui Li
- Department of Pathology, The Second Hospital Affiliated to Shandong University, Jinan, China
| | - Jinpeng Sun
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Xiao Yu
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Zhongyin Zhang
- Departments of Medicinal Chemistry and Molecular Pharmacology and Chemistry, Center for Cancer Research, Institute for Drug Discovery, Purdue University, West Lafayette, Indiana, USA
| | - Zongli Zhang
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
| | - Yunfei Xu
- Department of General Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
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2
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Hendriks WJAJ, van Cruchten RTP, Pulido R. Hereditable variants of classical protein tyrosine phosphatase genes: Will they prove innocent or guilty? Front Cell Dev Biol 2023; 10:1051311. [PMID: 36755664 PMCID: PMC9900141 DOI: 10.3389/fcell.2022.1051311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 12/28/2022] [Indexed: 01/24/2023] Open
Abstract
Protein tyrosine phosphatases, together with protein tyrosine kinases, control many molecular signaling steps that control life at cellular and organismal levels. Impairing alterations in the genes encoding the involved proteins is expected to profoundly affect the quality of life-if compatible with life at all. Here, we review the current knowledge on the effects of germline variants that have been reported for genes encoding a subset of the protein tyrosine phosphatase superfamily; that of the thirty seven classical members. The conclusion must be that the newest genome research tools produced an avalanche of data that suggest 'guilt by association' for individual genes to specific disorders. Future research should face the challenge to investigate these accusations thoroughly and convincingly, to reach a mature genotype-phenotype map for this intriguing protein family.
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Affiliation(s)
- Wiljan J. A. J. Hendriks
- Department of Cell Biology, Radboud University Medical Centre, Nijmegen, The Netherlands,*Correspondence: Wiljan J. A. J. Hendriks,
| | | | - Rafael Pulido
- Biomarkers in Cancer Unit, Biocruces Bizkaia Health Research Institute, Barakaldo, Spain,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
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3
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Watt AT, Head B, Leonard SW, Tanguay RL, Traber MG. Gene Expression of CRAL_TRIO Family Proteins modulated by Vitamin E Deficiency in Zebrafish (Danio Rerio). J Nutr Biochem 2021; 97:108801. [PMID: 34119630 PMCID: PMC10129037 DOI: 10.1016/j.jnutbio.2021.108801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 04/19/2021] [Accepted: 06/01/2021] [Indexed: 11/15/2022]
Abstract
An evaluation of the impact of vitamin E deficiency on expression of the alpha-tocopherol transfer protein (α-TTP) and related CRAL_TRIO genes was undertaken using livers from adult zebrafish based on the hypothesis that increased lipid peroxidation would modulate gene expression. Zebrafish were fed either a vitamin E sufficient (E+) or deficient (E-) diet for 9 months, then fish were euthanized, and livers were harvested. Livers from the E+ relative to E- fish contained 40-times more α-tocopherol (P <0.0001) and one fourth the malondialdehyde (P = 0.0153). RNA was extracted from E+ and E- livers, then subject to evaluation of gene expression of ttpa and other genes of the CRAL_TRIO family, genes of antioxidant markers, and genes related to lipid metabolism. Ttpa expression was not altered by vitamin E status. However, one member of the CRAL_TRIO family, tyrosine-protein phosphatase non-receptor type 9 gene (ptpn9a), showed a 2.4-fold increase (P = 0.029) in E- relative to E+ livers. Further, we identified that the gene for choline kinase alpha (chka) showed a 3.0-fold increase (P = 0.010) in E- livers. These outcomes are consistent with our previous findings that show vitamin E deficiency increased lipid peroxidation causing increases in phospholipid turnover.
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Affiliation(s)
- Alexander T Watt
- Linus Pauling Institute, Oregon State University, Corvallis, Oregon; Integrative Biology Program, Oregon State University, Corvallis, Oregon
| | - Brian Head
- Linus Pauling Institute, Oregon State University, Corvallis, Oregon; Molecular and Cell Biology Program
| | - Scott W Leonard
- Linus Pauling Institute, Oregon State University, Corvallis, Oregon
| | - Robyn L Tanguay
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon
| | - Maret G Traber
- Linus Pauling Institute, Oregon State University, Corvallis, Oregon; School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon.
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4
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Xiong J, Niu Y, Liu W, Zeng F, Cheng JF, Chen SQ, Zeng XZ. Effect of L3MBTL3/PTPN9 polymorphisms on risk to alcohol-induced ONFH in Chinese Han population. Neurol Sci 2021; 43:2823-2830. [PMID: 34373992 DOI: 10.1007/s10072-021-05486-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 07/16/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE Alcohol-induced osteonecrosis femoral head necrosis (ONFH) is a disease that seriously affects human health. Abnormal expression of L3MBTL3/PTPN9 gene can cause a variety of human diseases. The purpose of this study is to investigate the effect of L3MBTL3/PTPN9 gene polymorphism on the susceptibility of alcohol-induced ONFH in Chinese Han population. METHODS A total of 308 alcohol-induced ONFH patients and 425 healthy controls were enrolled in this case-control study. Alleles, genotypes, genetic models, haplotypes, and multifactor dimensionality reduction analyses (MDR) based on age-corrected by using odds ratio (OR) and 95% confidence interval (CI) were performed. RESULTS Our result revealed rs2068957 in the L3MBTL3 gene increased the risk of alcohol ONFH under the recessive model after correction. Besides, we also found that rs75393192 in the PTPN9 gene was a protective site in stratification over 40 years of age and stage. In stratified analysis of necrotic sites, we only found that rs2068957 was associated with increased susceptibility of alcohol-induced ONFH under the co-dominant model and recessive model. Haplotype "GC" in the block (rs76107647|rs10851882 in PTPN9 gene) significantly decreased the susceptibility of alcoholic ONFH. CONCLUSIONS Our results provide evidence that L3MBTL3/PTPN9 polymorphisms are associated with alcohol-induced ONFH risk in Chinese Han population.
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Affiliation(s)
- Jun Xiong
- Department of Orthopedic Trauma, the Hainan Affiliated Hospital of Hainan Medical University, No. 19, Xiuhua Road, Haikou, 570311, Hainan Province, China
| | - Yi Niu
- Department of Emergency and Critical Care Medicine, the Haikou Orthopedic and Diabetes Hospital of Shanghai Sixth People's Hospital, No. 3, Changxiu Road, Haikou, 570300, Hainan Province, China
| | - Wei Liu
- Department of Orthopedic Trauma, the Hainan Affiliated Hospital of Hainan Medical University, No. 19, Xiuhua Road, Haikou, 570311, Hainan Province, China
| | - Fan Zeng
- Department of Orthopedic Trauma, the Hainan Affiliated Hospital of Hainan Medical University, No. 19, Xiuhua Road, Haikou, 570311, Hainan Province, China
| | - Jian-Fei Cheng
- Department of Orthopedic Trauma, the Hainan Affiliated Hospital of Hainan Medical University, No. 19, Xiuhua Road, Haikou, 570311, Hainan Province, China
| | - Shi-Qiang Chen
- Department of Orthopedic Trauma, the Hainan Affiliated Hospital of Hainan Medical University, No. 19, Xiuhua Road, Haikou, 570311, Hainan Province, China
| | - Xiang-Zhou Zeng
- Department of Pharmacology, School of Basic Medicine and Life Science, the Hainan Medical University, No. 3, Xueyuan Road, Haikou, 571199, Hainan Province, China.
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Abstract
A major goal of synthetic biology is to understand the transition between non-living matter and life. The bottom-up development of an artificial cell would provide a minimal system with which to study the border between chemistry and biology. So far, a fully synthetic cell has remained elusive, but chemists are progressing towards this goal by reconstructing cellular subsystems. Cell boundaries, likely in the form of lipid membranes, were necessary for the emergence of life. In addition to providing a protective barrier between cellular cargo and the external environment, lipid compartments maintain homeostasis with other subsystems to regulate cellular processes. In this Review, we examine different chemical approaches to making cell-mimetic compartments. Synthetic strategies to drive membrane formation and function, including bioorthogonal ligations, dissipative self-assembly and reconstitution of biochemical pathways, are discussed. Chemical strategies aim to recreate the interactions between lipid membranes, the external environment and internal biomolecules, and will clarify our understanding of life at the interface of chemistry and biology.
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6
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Xu YF, Chen X, Yang Z, Xiao P, Liu CH, Li KS, Yang XZ, Wang YJ, Zhu ZL, Xu ZG, Zhang S, Wang C, Song YC, Zhao WD, Wang CH, Ji ZL, Zhang ZY, Cui M, Sun JP, Yu X. PTP-MEG2 regulates quantal size and fusion pore opening through two distinct structural bases and substrates. EMBO Rep 2021; 22:e52141. [PMID: 33764618 DOI: 10.15252/embr.202052141] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/26/2021] [Accepted: 02/18/2021] [Indexed: 02/02/2023] Open
Abstract
Tyrosine phosphorylation of secretion machinery proteins is a crucial regulatory mechanism for exocytosis. However, the participation of protein tyrosine phosphatases (PTPs) in different exocytosis stages has not been defined. Here we demonstrate that PTP-MEG2 controls multiple steps of catecholamine secretion. Biochemical and crystallographic analyses reveal key residues that govern the interaction between PTP-MEG2 and its substrate, a peptide containing the phosphorylated NSF-pY83 site, specify PTP-MEG2 substrate selectivity, and modulate the fusion of catecholamine-containing vesicles. Unexpectedly, delineation of PTP-MEG2 mutants along with the NSF binding interface reveals that PTP-MEG2 controls the fusion pore opening through NSF independent mechanisms. Utilizing bioinformatics search and biochemical and electrochemical screening approaches, we uncover that PTP-MEG2 regulates the opening and extension of the fusion pore by dephosphorylating the DYNAMIN2-pY125 and MUNC18-1-pY145 sites. Further structural and biochemical analyses confirmed the interaction of PTP-MEG2 with MUNC18-1-pY145 or DYNAMIN2-pY125 through a distinct structural basis compared with that of the NSF-pY83 site. Our studies thus provide mechanistic insights in complex exocytosis processes.
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Affiliation(s)
- Yun-Fei Xu
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, China.,Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Xu Chen
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Medicine, Jinan, China
| | - Zhao Yang
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, China
| | - Peng Xiao
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, China
| | - Chun-Hua Liu
- Department of Physiology, Shandong First Medical University, Taian, China
| | - Kang-Shuai Li
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, China.,Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Xiao-Zhen Yang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Yi-Jing Wang
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, China
| | - Zhong-Liang Zhu
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Zhi-Gang Xu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, China
| | - Sheng Zhang
- Departments of Medicinal Chemistry and Molecular Pharmacology and of Chemistry, Center for Cancer Research, and Institute for Drug Discovery, Purdue University, West Lafayette, IN, USA
| | - Chuan Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - You-Chen Song
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Wei-Dong Zhao
- Department of Developmental Cell Biology, China Medical University, Shenyang, China
| | - Chang-He Wang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Zhi-Liang Ji
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Zhong-Yin Zhang
- Departments of Medicinal Chemistry and Molecular Pharmacology and of Chemistry, Center for Cancer Research, and Institute for Drug Discovery, Purdue University, West Lafayette, IN, USA
| | - Min Cui
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Medicine, Jinan, China
| | - Jin-Peng Sun
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, China
| | - Xiao Yu
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, Shandong University School of Medicine, Jinan, China
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7
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Liu X, Li Z, Yan Y, Li Y, Wu H, Pei J, Yan P, Yang R, Guo X, Lan X. Selection and introgression facilitated the adaptation of Chinese native endangered cattle in extreme environments. Evol Appl 2021; 14:860-873. [PMID: 33767758 PMCID: PMC7980270 DOI: 10.1111/eva.13168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/31/2020] [Accepted: 11/03/2020] [Indexed: 12/18/2022] Open
Abstract
Although persistent efforts have identified and characterized a few candidate genes and related biological processes with potential functions in the adaptation of many species to extreme environments, few works have been conducted to determine the genomic basis of adaptation in endangered livestock breeds that have been living in extreme conditions for more than thousands of years. To fill this gap, we sequenced the whole genomes of nine individuals from three Chinese native endangered cattle breeds that are living in high-altitude or arid environments. Phylogenetic and evolutionary history analyses of these three and other six breeds showed that the genetic structure of the cattle populations is primarily related to geographic location. Interestingly, we identified pervasive introgression from the yak to Zhangmu cattle (ZMC) that cover several genes (e.g., NOS2, EGLN1 and EPAS1) involved in the hypoxia response and previously identified as positive selection genes in other species, which suggested that the adaptive introgression from yak may have contributed to the adaptation of ZMC to high-altitude environments. In addition, by contrasting the breeds in opposite living conditions, we revealed a set of candidate genes with various functions from hypoxia response, water metabolism, immune response and body shape change to embryo development and skeletal system development, etc., that may be related to high-altitude or arid adaptation. Our research provides new insights into the recovery and adaptation of endangered native cattle and other species in extreme environments and valuable resources for future research on animal husbandry to cope with climate change.
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Affiliation(s)
- Xinfeng Liu
- College of Animal Science and TechnologyNorthwest A&F UniversityYanglingChina
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Zhaohong Li
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Yubin Yan
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Ye Li
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Hui Wu
- College of Animal Science and TechnologyNorthwest A&F UniversityYanglingChina
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Jie Pei
- Lanzhou Institute of Husbandry and Pharmaceutical SciencesChinese Academy of Agricultural SciencesLanzhouChina
| | - Ping Yan
- Lanzhou Institute of Husbandry and Pharmaceutical SciencesChinese Academy of Agricultural SciencesLanzhouChina
| | - Ruolin Yang
- College of Life SciencesNorthwest A&F UniversityYanglingChina
| | - Xian Guo
- Lanzhou Institute of Husbandry and Pharmaceutical SciencesChinese Academy of Agricultural SciencesLanzhouChina
| | - Xianyong Lan
- College of Animal Science and TechnologyNorthwest A&F UniversityYanglingChina
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8
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Lete MG, Tripathi A, Chandran V, Bankaitis VA, McDermott MI. Lipid transfer proteins and instructive regulation of lipid kinase activities: Implications for inositol lipid signaling and disease. Adv Biol Regul 2020; 78:100740. [PMID: 32992233 PMCID: PMC7986245 DOI: 10.1016/j.jbior.2020.100740] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/16/2020] [Accepted: 06/24/2020] [Indexed: 05/17/2023]
Abstract
Cellular membranes are critical platforms for intracellular signaling that involve complex interfaces between lipids and proteins, and a web of interactions between a multitude of lipid metabolic pathways. Membrane lipids impart structural and functional information in this regulatory circuit that encompass biophysical parameters such as membrane thickness and fluidity, as well as chaperoning the interactions of protein binding partners. Phosphatidylinositol and its phosphorylated derivatives, the phosphoinositides, play key roles in intracellular membrane signaling, and these involvements are translated into an impressively diverse set of biological outcomes. The phosphatidylinositol transfer proteins (PITPs) are key regulators of phosphoinositide signaling. Found in a diverse array of organisms from plants, yeast and apicomplexan parasites to mammals, PITPs were initially proposed to be simple transporters of lipids between intracellular membranes. It now appears increasingly unlikely that the soluble versions of these proteins perform such functions within the cell. Rather, these serve to facilitate the activity of intrinsically biologically insufficient inositol lipid kinases and, in so doing, promote diversification of the biological outcomes of phosphoinositide signaling. The central engine for execution of such functions is the lipid exchange cycle that is a fundamental property of PITPs. How PITPs execute lipid exchange remains very poorly understood. Molecular dynamics simulation approaches are now providing the first atomistic insights into how PITPs, and potentially other lipid-exchange/transfer proteins, operate.
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Affiliation(s)
- Marta G Lete
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA; Institute Biofisika (UPV/EHU, CSIC) and University of the Basque Country, Leioa, Spain
| | - Ashutosh Tripathi
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA
| | - Vijay Chandran
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA
| | - Vytas A Bankaitis
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843-2128, USA; Department of Chemistry, Texas A&M University, College Station, TX, 77840, USA
| | - Mark I McDermott
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA.
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Chou HY, Lee YT, Lin YJ, Wen JK, Peng WH, Hsieh PL, Lin SY, Hung CC, Chen GC. PTPN9-mediated dephosphorylation of VTI1B promotes ATG16L1 precursor fusion and autophagosome formation. Autophagy 2020; 17:2750-2765. [PMID: 33112705 DOI: 10.1080/15548627.2020.1838117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Macroautophagy/autophagy is an evolutionarily conserved intracellular pathway for the degradation of cytoplasmic materials. Under stress conditions, autophagy is upregulated and double-membrane autophagosomes are formed by the expansion of phagophores. The ATG16L1 precursor fusion contributes to development of phagophore structures and is critical for the biogenesis of autophagosomes. Here, we discovered a novel role of the protein tyrosine phosphatase PTPN9 in the regulation of homotypic ATG16L1 vesicle fusion and early autophagosome formation. Depletion of PTPN9 and its Drosophila homolog Ptpmeg2 impaired autophagosome formation and autophagic flux. PTPN9 colocalized with ATG16L1 and was essential for homotypic fusion of ATG16L1+ vesicles during starvation-induced autophagy. We further identified the Q-SNARE VTI1B as a substrate target of PTPN9 phosphatase. Like PTPN9, the VTI1B nonphosphorylatable mutant but not the phosphomimetic mutant enhanced SNARE complex assembly and autophagic flux. Our findings highlight the important role of PTPN9 in the regulation of ATG16L1+ autophagosome precursor fusion and autophagosome biogenesis through modulation of VTI1B phosphorylation status.Abbreviations: csw: corkscrew; EBSS: Earle's balanced salt solution; ERGIC: ER-Golgi intermediate compartment; ESCRT: endosomal sorting complexes required for transport; mop: myopic; NSF: N-ethylmaleimide-sensitive factor; PAS: phagophore assembly site; PolyQ: polyglutamine; PtdIns3P: phosphatidylinositol-3-phosphate; PTK: protein tyrosine kinase; PTM: posttranslational modification; PTP: protein tyrosine phosphatase; PTPN23/HD-PTP: protein tyrosine phosphatase non-receptor type 23; SNARE: soluble N-ethylmaleimide sensitive factor attachment protein receptor; STX7: syntaxin 7; STX8: syntaxin 8; STX17: syntaxin 17; VAMP3: vesicle associated membrane protein 3; VAMP7: vesicle associated membrane protein 7; VTI1B: vesicle transport through interaction with t-SNAREs 1B; YKT6: YKT6 v-SNARE homolog; ZFYVE1/DFCP1: zinc finger FYVE-type containing 1.
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Affiliation(s)
- He-Yen Chou
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yi-Tang Lee
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Yuchieh Jay Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan.,Chemical Biology and Molecular Biophysics, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan
| | - Jung-Kun Wen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Wen-Hsin Peng
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Pei-Lien Hsieh
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Shu-Yu Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chin-Chun Hung
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Guang-Chao Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan.,Chemical Biology and Molecular Biophysics, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan
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10
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Castro-Sánchez P, Aguilar-Sopeña O, Alegre-Gómez S, Ramirez-Munoz R, Roda-Navarro P. Regulation of CD4 + T Cell Signaling and Immunological Synapse by Protein Tyrosine Phosphatases: Molecular Mechanisms in Autoimmunity. Front Immunol 2019; 10:1447. [PMID: 31297117 PMCID: PMC6607956 DOI: 10.3389/fimmu.2019.01447] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/10/2019] [Indexed: 12/13/2022] Open
Abstract
T cell activation and effector function is mediated by the formation of a long-lasting interaction established between T cells and antigen-presenting cells (APCs) called immunological synapse (IS). During T cell activation, different signaling molecules as well as the cytoskeleton and the endosomal compartment are polarized to the IS. This molecular dynamics is tightly regulated by phosphorylation networks, which are controlled by protein tyrosine phosphatases (PTPs). While some PTPs are known to be important regulators of adhesion, ligand discrimination or the stimulation threshold, there is still little information about the regulatory role of PTPs in cytoskeleton rearrangements and endosomal compartment dynamics. Besides, spatial and temporal regulation of PTPs and substrates at the IS is only barely known. Consistent with an important role of PTPs in T cell activation, multiple mutations as well as altered expression levels or dynamic behaviors have been associated with autoimmune diseases. However, the precise mechanism for the regulation of T cell activation and effector function by PTPs in health and autoimmunity is not fully understood. Herein, we review the current knowledge about the regulatory role of PTPs in CD4+ T cell activation, IS assembly and effector function. The potential molecular mechanisms mediating the action of these enzymes in autoimmune disorders are discussed.
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Affiliation(s)
- Patricia Castro-Sánchez
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
| | - Oscar Aguilar-Sopeña
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
| | - Sergio Alegre-Gómez
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
| | - Rocio Ramirez-Munoz
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
| | - Pedro Roda-Navarro
- Department of Immunology, Ophthalmology and ENT, School of Medicine, Complutense University, Madrid, Spain.,Health Research Institute '12 de Octubre (imas12)', Madrid, Spain
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11
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Ruete MC, Zarelli VEP, Masone D, de Paola M, Bustos DM, Tomes CN. A connection between reversible tyrosine phosphorylation and SNARE complex disassembly activity of N-ethylmaleimide-sensitive factor unveiled by the phosphomimetic mutant N-ethylmaleimide-sensitive factor-Y83E. ACTA ACUST UNITED AC 2019; 25:344-358. [DOI: 10.1093/molehr/gaz031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/16/2019] [Accepted: 06/03/2019] [Indexed: 12/26/2022]
Abstract
Abstract
N-ethylmaleimide-sensitive factor (NSF) disassembles fusion-incompetent cis soluble-NSF attachment protein receptor (SNARE) complexes making monomeric SNAREs available for subsequent trans pairing and fusion. In most cells the activity of NSF is constitutive, but in Jurkat cells and sperm it is repressed by tyrosine phosphorylation; the phosphomimetic mutant NSF–Y83E inhibits secretion in the former. The questions addressed here are if and how the NSF mutant influences the configuration of the SNARE complex. Our model is human sperm, where the initiation of exocytosis (acrosome reaction (AR)) de-represses the activity of NSF through protein tyrosine phosphatase 1B (PTP1B)-mediated dephosphorylation. We developed a fluorescence microscopy-based method to show that capacitation increased, and challenging with an AR inducer decreased, the number of cells with tyrosine-phosphorylated PTP1B substrates in the acrosomal domain. Results from bioinformatic and biochemical approaches using purified recombinant proteins revealed that NSF–Y83E bound PTP1B and thereupon inhibited its catalytic activity. Mutant NSF introduced into streptolysin O-permeabilized sperm impaired cis SNARE complex disassembly, blocking the AR; subsequent addition of PTP1B rescued exocytosis. We propose that NSF–Y83E prevents endogenous PTP1B from dephosphorylating sperm NSF, thus maintaining NSF’s activity in a repressed mode and the SNARE complex unable to dissociate. The contribution of this paper to the sperm biology field is the detection of PTP1B substrates, one of them likely being NSF, whose tyrosine phosphorylation status varies during capacitation and the AR. The contribution of this paper to the membrane traffic field is to have generated direct evidence that explains the dominant-negative role of the phosphomimetic mutant NSF–Y83E.
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Affiliation(s)
- María Celeste Ruete
- Instituto de Histología y Embriología de Mendoza Dr Mario H. Burgos–CONICET, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Valeria Eugenia Paola Zarelli
- Instituto de Histología y Embriología de Mendoza Dr Mario H. Burgos–CONICET, Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Diego Masone
- Instituto de Histología y Embriología de Mendoza Dr Mario H. Burgos–CONICET, Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ingeniería, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Matilde de Paola
- Instituto de Histología y Embriología de Mendoza Dr Mario H. Burgos–CONICET, Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
- Instituto de Medicina y Biología Experimental de Cuyo–Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Diego Martín Bustos
- Instituto de Histología y Embriología de Mendoza Dr Mario H. Burgos–CONICET, Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Claudia Nora Tomes
- Instituto de Histología y Embriología de Mendoza Dr Mario H. Burgos–CONICET, Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
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12
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Reinhard J, Wiemann S, Joachim SC, Palmhof M, Woestmann J, Denecke B, Wang Y, Downey GP, Faissner A. Heterozygous Meg2 Ablation Causes Intraocular Pressure Elevation and Progressive Glaucomatous Neurodegeneration. Mol Neurobiol 2019; 56:4322-4345. [PMID: 30315478 DOI: 10.1007/s12035-018-1376-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 09/28/2018] [Indexed: 02/07/2023]
Abstract
Glaucomatous neurodegeneration represents one of the major causes of irreversible blindness worldwide. Yet, the detailed molecular mechanisms that initiate optic nerve damage and retinal ganglion cell (RGC) loss are not fully understood. Members of the protein tyrosine phosphatase (PTP) superfamily are key players in numerous neurodegenerative diseases. In order to investigate the potential functional relevance of the PTP megakaryocyte 2 (Meg2) in retinal neurodegeneration, we analyzed Meg2 knockout (KO) and heterozygous (HET)-synonym protein-tyrosine phosphatase non-receptor type 9 (Ptpn9)-mice. Interestingly, via global microarray and quantitative real-time PCR (RT-qPCR) analyses of Meg2 KO and HET retinae, we observed a dysregulation of several candidate genes that are highly associated with retinal degeneration and intraocular pressure (IOP) elevation, the main risk factor for glaucoma. Subsequent IOP measurements in Meg2 HET mice verified progressive age-dependent IOP elevation. Ultrastructural analyses and immunohistochemistry showed severe optic nerve degeneration accompanied by a dramatic loss of RGCs. Additionally, HET mice displayed reactive micro-/macrogliosis and early activation of the classical complement cascade with pronounced deposition of the membrane attack complex (MAC) in the retina and optic nerve. When treated with latanoprost, significant IOP lowering prevented RGC loss and microglial invasion in HET mice. Finally, electroretinogram (ERG) recordings revealed reduced a- and b-wave amplitudes, indicating impaired retinal functionality in Meg2 HET mice. Collectively, our findings indicate that the heterozygous loss of Meg2 in mice is sufficient to cause IOP elevation and glaucomatous neurodegeneration. Thus, Meg2 HET mice may serve as a novel animal model to study the pathomechanism involved in the onset and progression of glaucoma.
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Affiliation(s)
- Jacqueline Reinhard
- Department of Cell Morphology and Molecular Neurobiology, NDEF 05/594, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Susanne Wiemann
- Department of Cell Morphology and Molecular Neurobiology, NDEF 05/594, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Stephanie C Joachim
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892, Bochum, Germany
| | - Marina Palmhof
- Experimental Eye Research Institute, University Eye Hospital, Ruhr-University Bochum, In der Schornau 23-25, 44892, Bochum, Germany
| | - Julia Woestmann
- Department of Cell Morphology and Molecular Neurobiology, NDEF 05/594, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Bernd Denecke
- Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Yingchun Wang
- Division of Respirology, Department of Medicine, University of Toronto and Toronto General Hospital Research Institute of the University Health Network, 610 University Avenue, Toronto, ON, M5S 1A8, Canada
| | - Gregory P Downey
- Division of Pulmonary Sciences and Critical Care Medicine, Departments of Medicine and Immunology and Microbiology, University of Colorado, Aurora, CO, 80045, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Departments of Medicine, Pediatrics and Biomedical Research, National Jewish Health, 1400 Jackson Street, Denver, CO, 80206, USA
| | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology, NDEF 05/594, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Universitätsstrasse 150, 44780, Bochum, Germany.
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Ying D, Ruan Y, Zhou X. MEG2 inhibits the growth and metastasis of hepatocellular carcinoma by inhibiting AKT pathway. Gene 2018; 687:1-8. [PMID: 30399427 DOI: 10.1016/j.gene.2018.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 10/22/2018] [Accepted: 11/01/2018] [Indexed: 11/19/2022]
Abstract
MEG2 was recently found to have important functions in human cancers. However, the expression status and biological functions of MEG2 in hepatocellular carcinoma (HCC) remain unknown. In this study, we demonstrated that MEG2 expression was reduced in HCC tissues and cell lines using qRT-PCR, western blot and immunohistochemical staining. Decreased MEG2 expression predicted unfavorable clinical features and decreased overall survival and disease-free survival of HCC patients. In vitro functional assays showed that overexpression of MEG2 inhibited the cell viability, migration and invasion of HCCLM3 cells while MEG2 knockdown promoted these biological functions of Hep3B cells. Subcutaneous injection model and tail vein injection model showed that forced expression of MEG2 in HCCLM3 decreased the growth and lung metastasis of HCCLM3 cells in nude mice. Mechanically, MEG2 inhibited the EMT and AKT phosphorylation of HCC cells. The promoting effects of MEG2 knockdown on EMT, cell viability, proliferation, migration and invasion of Hep3B cells was blocked by AKT phosphorylation inhibition. In all, this study demonstrates that MEG2 inhibits the growth and metastasis of hepatocellular carcinoma by inhibiting AKT pathway.
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MESH Headings
- Animals
- Apoptosis
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Cell Movement
- Cell Proliferation
- Female
- Follow-Up Studies
- Gene Expression Regulation, Neoplastic
- Humans
- Liver Neoplasms/genetics
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Lung Neoplasms/secondary
- Lymphatic Metastasis
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Nude
- Middle Aged
- Neoplasm Invasiveness
- Prognosis
- Protein Tyrosine Phosphatases, Non-Receptor/genetics
- Protein Tyrosine Phosphatases, Non-Receptor/metabolism
- Proto-Oncogene Proteins c-akt/genetics
- Proto-Oncogene Proteins c-akt/metabolism
- Survival Rate
- Tumor Cells, Cultured
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Dongjian Ying
- Department of Minimal Invasive Surgery, Ningbo Medical Center Lihuili Eastern Hospital, Ningbo 315040, Zhejiang, China
| | - Yi Ruan
- Department of Minimal Invasive Surgery, Ningbo Medical Center Lihuili Eastern Hospital, Ningbo 315040, Zhejiang, China
| | - Xinhua Zhou
- Department of Minimal Invasive Surgery, Ningbo Medical Center Lihuili Eastern Hospital, Ningbo 315040, Zhejiang, China.
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14
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Huang Y, Zhang Y, Ge L, Lin Y, Kwok HF. The Roles of Protein Tyrosine Phosphatases in Hepatocellular Carcinoma. Cancers (Basel) 2018; 10:cancers10030082. [PMID: 29558404 PMCID: PMC5876657 DOI: 10.3390/cancers10030082] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 03/12/2018] [Accepted: 03/15/2018] [Indexed: 02/08/2023] Open
Abstract
The protein tyrosine phosphatase (PTP) family is involved in multiple cellular functions and plays an important role in various pathological and physiological processes. In many chronic diseases, for example cancer, PTP is a potential therapeutic target for cancer treatment. In the last two decades, dozens of PTP inhibitors which specifically target individual PTP molecules were developed as therapeutic agents. Hepatocellular carcinoma (HCC) is one of the most common malignant tumors and is the second most lethal cancer worldwide due to a lack of effective therapies. Recent studies have unveiled both oncogenic and tumor suppressive functions of PTP in HCC. Here, we review the current knowledge on the involvement of PTP in HCC and further discuss the possibility of targeting PTP in HCC.
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Affiliation(s)
- Yide Huang
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China.
- Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau, China.
| | - Yafei Zhang
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China.
| | - Lilin Ge
- Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau, China.
- Jiangsu Key Laboratory for Functional Substance of Chinese Medicine, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
| | - Yao Lin
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China.
| | - Hang Fai Kwok
- Faculty of Health Sciences, University of Macau, Avenida de Universidade, Taipa, Macau, China.
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15
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Liu Z, Sun F, Hong Y, Liu Y, Fen M, Yin K, Ge X, Wang F, Chen X, Guan W. MEG2 is regulated by miR-181a-5p and functions as a tumour suppressor gene to suppress the proliferation and migration of gastric cancer cells. Mol Cancer 2017; 16:133. [PMID: 28747184 PMCID: PMC5530520 DOI: 10.1186/s12943-017-0695-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 07/10/2017] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Protein-tyrosine phosphatase MEG2 (MEG2) is a classic tyrosine-specific protein tyrosine phosphatase (PTP). It has been reported that MEG2 participates in the carcinogenesis of the breast and liver. However, functions of MEG2 in gastric cancer remain poorly understood. METHODS We examined the expression of MEG2 protein by western blotting and that of miR-181a-5p by qRT-PCR. We used bioinformatic analyses to search for miRNAs that potentially target MEG2. We performed a luciferase reporter assay to investigate the interaction between miR-181a-5p and MEG2. In addition, we assessed the effects of MEG2 and miR-181a-5p on gastric cancer cells in vitro and in vivo. RESULTS We found that MEG2 is downregulated in human gastric cancer and that miR-181a-5p is predicted to be a potential regulator of MEG2. We also observed that expression of MEG2 is reversely correlated with that of miR-181a-5p in gastric cancer. Moreover, we observed that MEG2 regulation by miR-181a-5p significantly suppresses the proliferation and migration of gastric cancer cells in vitro and decelerates tumour growth in vivo. CONCLUSIONS Our results revealed that MEG2 is a tumour suppressor gene and negatively regulated by miR-181a-5p in gastric cancer.
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Affiliation(s)
- Zhijian Liu
- Department of Gastrointestinal Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China
| | - Feng Sun
- Department of Gastrointestinal Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China
| | - Yeting Hong
- State Key Laboratory of Pharmaceutical Biotechnology, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210046, China
| | - Yanqing Liu
- State Key Laboratory of Pharmaceutical Biotechnology, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210046, China
| | - Min Fen
- Department of Gastrointestinal Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China
| | - Kai Yin
- Department of Gastrointestinal Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China
| | - Xiaolong Ge
- Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, East Qingchun Road, Hangzhou, 310016, China
| | - Feng Wang
- Department of Gastrointestinal Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China.
| | - Xi Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210046, China.
| | - Wenxian Guan
- Department of Gastrointestinal Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing, Jiangsu, 210008, China.
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16
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Zhu J, Li H, Ma J, Huang H, Qin J, Li Y. PTPN9 promotes cell proliferation and invasion in Eca109 cells and is negatively regulated by microRNA-126. Oncol Lett 2017; 14:1419-1426. [PMID: 28789358 PMCID: PMC5529898 DOI: 10.3892/ol.2017.6315] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 04/13/2017] [Indexed: 12/23/2022] Open
Abstract
Protein tyrosine phosphatase non-receptor type 9 (PTPN9), also named PTP-MEG2, is an important member of the protein tyrosine phosphatase family that is involved in variety of human diseases. However, the role of PTPN9 in esophageal squamous cell carcinoma (ESCC) remains to be established. The present evaluated the potential effect and underlying mechanism of action of PTPN9 in ESCC. Immunohistochemistry was performed to detect PTPN9 protein expression in 84 ESCC tumor specimens and 30 normal esophageal tissues. The association between positive expression of PTPN9 and clinicopathological features and prognosis was analyzed. The prognostic role of PTPN9 was further investigated using multivariate regression analysis. PTPN9-small interfering RNA and microRNA (miR-126)-mimics were transfected into Eca109 cells to construct PTPN9 silencing and an miR-126 ectopic expression cell model. Reverse transcription-quantitative polymerase chain reaction, western blot analysis, cell counting kit-8, Transwell assays and flow cytometry were used to investigate the role of PTPN9 in the process of ESCC progression and its potential downstream signaling pathway. Immunohistochemical analysis revealed that PTPN9 was upregulated in ESCC tumor specimens compared with normal esophageal tissues. The χ2 test indicated that positive expression of PTPN9 was correlated with tumor node metastasis stage, tumor classification and node classification. Patients with PTPN9 positive expression had shorter survival time, compared with those that were PTPN9 negative. Multivariate regression analysis with the Cox proportional hazards regression model revealed that PTPN9 expression was a prognostic factor of overall survival for patients with ESCC. Using RNA interference, the present study demonstrated that knockdown of PTPN9 significantly suppressed cell proliferation and invasion in Eca109. Additionally, it was hypothesized that miR-126, described as a tumor suppressor in ESCC, may act at least in part via its inhibition of PTPN9 at the post-transcriptional level. To the best of our knowledge, this is the first study to demonstrate that PTPN9 is overexpressed in ESCC and associated with poor survival, and may therefore be important in the pathogenesis of ESCC.
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Affiliation(s)
- Junwei Zhu
- Department of Thoracic Surgery, The Affiliated Tumor Hospital of Zhengzhou University, Zhengzhou, Henan 450008, P.R. China
| | - Haomiao Li
- Department of Thoracic Surgery, The Affiliated Tumor Hospital of Zhengzhou University, Zhengzhou, Henan 450008, P.R. China
| | - Jun Ma
- Department of Gastroenterology, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450014, P.R. China
| | - Haibo Huang
- Department of Thoracic Surgery, The Affiliated Tumor Hospital of Zhengzhou University, Zhengzhou, Henan 450008, P.R. China
| | - Jianjun Qin
- Department of Thoracic Surgery, The Affiliated Tumor Hospital of Zhengzhou University, Zhengzhou, Henan 450008, P.R. China
| | - Yin Li
- Department of Thoracic Surgery, The Affiliated Tumor Hospital of Zhengzhou University, Zhengzhou, Henan 450008, P.R. China
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17
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Gene Expression Profiles of Human Phosphotyrosine Phosphatases Consequent to Th1 Polarisation and Effector Function. J Immunol Res 2017; 2017:8701042. [PMID: 28393080 PMCID: PMC5368384 DOI: 10.1155/2017/8701042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 02/14/2017] [Indexed: 11/30/2022] Open
Abstract
Phosphotyrosine phosphatases (PTPs) constitute a complex family of enzymes that control the balance of intracellular phosphorylation levels to allow cell responses while avoiding the development of diseases. Despite the relevance of CD4 T cell polarisation and effector function in human autoimmune diseases, the expression profile of PTPs during T helper polarisation and restimulation at inflammatory sites has not been assessed. Here, a systematic analysis of the expression profile of PTPs has been carried out during Th1-polarising conditions and upon PKC activation and intracellular raise of Ca2+ in effector cells. Changes in gene expression levels suggest a previously nonnoted regulatory role of several PTPs in Th1 polarisation and effector function. A substantial change in the spatial compartmentalisation of ERK during T cell responses is proposed based on changes in the dose of cytoplasmic and nuclear MAPK phosphatases. Our study also suggests a regulatory role of autoimmune-related PTPs in controlling T helper polarisation in humans. We expect that those PTPs that regulate T helper polarisation will constitute potential targets for intervening CD4 T cell immune responses in order to generate new therapies for the treatment of autoimmune diseases.
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18
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Corti F, Simons M. Modulation of VEGF receptor 2 signaling by protein phosphatases. Pharmacol Res 2017; 115:107-123. [PMID: 27888154 PMCID: PMC5205541 DOI: 10.1016/j.phrs.2016.11.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 11/18/2016] [Accepted: 11/21/2016] [Indexed: 12/21/2022]
Abstract
Phosphorylation of serines, threonines, and tyrosines is a central event in signal transduction cascades in eukaryotic cells. The phosphorylation state of any particular protein reflects a balance of activity between kinases and phosphatases. Kinase biology has been exhaustively studied and is reasonably well understood, however, much less is known about phosphatases. A large body of evidence now shows that protein phosphatases do not behave as indiscriminate signal terminators, but can function both as negative or positive regulators of specific signaling pathways. Genetic models have also shown that different protein phosphatases play precise biological roles in health and disease. Finally, genome sequencing has unveiled the existence of many protein phosphatases and associated regulatory subunits comparable in number to kinases. A wide variety of roles for protein phosphatase roles have been recently described in the context of cancer, diabetes, hereditary disorders and other diseases. In particular, there have been several recent advances in our understanding of phosphatases involved in regulation of vascular endothelial growth factor receptor 2 (VEGFR2) signaling. The receptor is the principal signaling molecule mediating a wide spectrum of VEGF signal and, thus, is of paramount significance in a wide variety of diseases ranging from cancer to cardiovascular to ophthalmic. This review focuses on the current knowledge about protein phosphatases' regulation of VEGFR2 signaling and how these enzymes can modulate its biological effects.
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Affiliation(s)
- Federico Corti
- Yale Cardiovascular Research Center, Department of Internal Medicine and Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
| | - Michael Simons
- Yale Cardiovascular Research Center, Department of Internal Medicine and Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
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19
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Zhang D, Marlin MC, Liang Z, Ahmad M, Ashpole NM, Sonntag WE, Zhao ZJ, Li G. The Protein Tyrosine Phosphatase MEG2 Regulates the Transport and Signal Transduction of Tropomyosin Receptor Kinase A. J Biol Chem 2016; 291:23895-23905. [PMID: 27655914 DOI: 10.1074/jbc.m116.728550] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 09/12/2016] [Indexed: 11/06/2022] Open
Abstract
Protein tyrosine phosphatase MEG2 (PTP-MEG2) is a unique nonreceptor tyrosine phosphatase associated with transport vesicles, where it facilitates membrane trafficking by dephosphorylation of the N-ethylmaleimide-sensitive fusion factor. In this study, we identify the neurotrophin receptor TrkA as a novel cargo whose transport to the cell surface requires PTP-MEG2 activity. In addition, TrkA is also a novel substrate of PTP-MEG2, which dephosphorylates both Tyr-490 and Tyr-674/Tyr-675 of TrkA. As a result, overexpression of PTP-MEG2 down-regulates NGF/TrkA signaling and blocks neurite outgrowth and differentiation in PC12 cells and cortical neurons.
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Affiliation(s)
- Dongmei Zhang
- From the Key Laboratory of Biopesticide and Chemical Biology, College of Plant Protection, Fujian Agriculture and Forestry University, 350002 Fuzhou, China.,the Departments of Biochemistry and Molecular Biology
| | | | - Zhimin Liang
- the Departments of Biochemistry and Molecular Biology
| | | | | | | | - Zhizhuang Joe Zhao
- Pathology.,Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Guangpu Li
- the Departments of Biochemistry and Molecular Biology, .,Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
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Kohansal-Nodehi M, Chua JJ, Urlaub H, Jahn R, Czernik D. Analysis of protein phosphorylation in nerve terminal reveals extensive changes in active zone proteins upon exocytosis. eLife 2016; 5. [PMID: 27115346 PMCID: PMC4894758 DOI: 10.7554/elife.14530] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/25/2016] [Indexed: 12/31/2022] Open
Abstract
Neurotransmitter release is mediated by the fast, calcium-triggered fusion of synaptic vesicles with the presynaptic plasma membrane, followed by endocytosis and recycling of the membrane of synaptic vesicles. While many of the proteins governing these processes are known, their regulation is only beginning to be understood. Here we have applied quantitative phosphoproteomics to identify changes in phosphorylation status of presynaptic proteins in resting and stimulated nerve terminals isolated from the brains of Wistar rats. Using rigorous quantification, we identified 252 phosphosites that are either up- or downregulated upon triggering calcium-dependent exocytosis. Particularly pronounced were regulated changes of phosphosites within protein constituents of the presynaptic active zone, including bassoon, piccolo, and RIM1. Additionally, we have mapped kinases and phosphatases that are activated upon stimulation. Overall, our study provides a snapshot of phosphorylation changes associated with presynaptic activity and provides a foundation for further functional analysis of key phosphosites involved in presynaptic plasticity. DOI:http://dx.doi.org/10.7554/eLife.14530.001 The human nervous system contains more than a hundred billion neurons that are connected with each other via junctions called synapses. When an electrical impulse travelling along a neuron arrives at a synapse, it triggers bubble-like packages called synaptic vesicles within the neuron to merge with the neuron’s surface membrane. The contents of these vesicles – chemical messengers called neurotransmitters – are then released into the synapse and carry the signal to the next neuron. Complex molecular machines made from many different proteins control the release of neurotransmitters. Quite a few of these proteins are regulated by the addition of phosphate groups at specific sites. However, not all of the proteins involved in the release of neurotransmitters have been studied in detail and it is largely unclear how most of them are regulated. Now, Kohansal-Nodehi et al. have used techniques involving mass spectrometry to find out which proteins have phosphate groups added or removed in neurons that are releasing neurotransmitters. The experiments used pinched-off synapses isolated from rat brains. These structures, referred to as “synaptosomes”, lend themselves to this kind of study because they can be induced to continuously release neurotransmitters for several minutes. Kohansal-Nodehi et al. identified over 250 specific sites on proteins in the synaptosomes where phosphate groups are attached, including many on the key proteins known to operate in neurotransmitter release. Moreover, some proteins were modified at multiple sites, especially the proteins that form a scaffold to capture synaptic vesicles close to the membrane and prepare them for release. The data also revealed important clues about the enzymes that either attach or remove the phosphate groups. Together, these findings provide new insights into the regulatory networks that control many proteins at the same time. The next challenge is to sort out which of these modifications change the interactions between the proteins that control neurotransmitter release, and to understand how these changes influence the trafficking of synaptic vesicles. DOI:http://dx.doi.org/10.7554/eLife.14530.002
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Affiliation(s)
| | - John Je Chua
- Interactomics and Intracellular Trafficking laboratory, National University of Singapore, Singapore, Singapore.,Department of Physiology, National University of Singapore, Singapore, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Neurobiology/Ageing Programme, National University of Singapore, Singapore, Singapore
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Bioanalytics Group, University Medical Center Göttingen, Göttingen, Germany
| | - Reinhard Jahn
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dominika Czernik
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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21
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Belluzzi E, Gonnelli A, Cirnaru MD, Marte A, Plotegher N, Russo I, Civiero L, Cogo S, Carrion MP, Franchin C, Arrigoni G, Beltramini M, Bubacco L, Onofri F, Piccoli G, Greggio E. LRRK2 phosphorylates pre-synaptic N-ethylmaleimide sensitive fusion (NSF) protein enhancing its ATPase activity and SNARE complex disassembling rate. Mol Neurodegener 2016; 11:1. [PMID: 26758690 PMCID: PMC4711005 DOI: 10.1186/s13024-015-0066-z] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 12/22/2015] [Indexed: 11/10/2022] Open
Abstract
Background Lrrk2, a gene linked to Parkinson’s disease, encodes a large scaffolding protein with kinase and GTPase activities implicated in vesicle and cytoskeletal-related processes. At the presynaptic site, LRRK2 associates with synaptic vesicles through interaction with a panel of presynaptic proteins. Results Here, we show that LRRK2 kinase activity influences the dynamics of synaptic vesicle fusion. We therefore investigated whether LRRK2 phosphorylates component(s) of the exo/endocytosis machinery. We have previously observed that LRRK2 interacts with NSF, a hexameric AAA+ ATPase that couples ATP hydrolysis to the disassembling of SNARE proteins allowing them to enter another fusion cycle during synaptic exocytosis. Here, we demonstrate that NSF is a substrate of LRRK2 kinase activity. LRRK2 phosphorylates full-length NSF at threonine 645 in the ATP binding pocket of D2 domain. Functionally, NSF phosphorylated by LRRK2 displays enhanced ATPase activity and increased rate of SNARE complex disassembling. Substitution of threonine 645 with alanine abrogates LRRK2-mediated increased ATPase activity. Conclusions Given that the most common Parkinson’s disease LRRK2 G2019S mutation displays increased kinase activity, our results suggest that mutant LRRK2 may impair synaptic vesicle dynamics via aberrant phosphorylation of NSF. Electronic supplementary material The online version of this article (doi:10.1186/s13024-015-0066-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Elisa Belluzzi
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy. .,Present Address: Rheumatology Unit, Department of Medicine - DIMED, University Hospital of Padova, Padova, Italy.
| | - Adriano Gonnelli
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy.
| | | | - Antonella Marte
- Department of Experimental Medicine, University of Genova, Genova, Italy.
| | - Nicoletta Plotegher
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy. .,Present Address: Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK.
| | - Isabella Russo
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy.
| | - Laura Civiero
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy.
| | - Susanna Cogo
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy.
| | - Maria Perèz Carrion
- San Raffaele Scientific Park & University Vita-Salute San Raffaele, Milan, Italy.
| | - Cinzia Franchin
- Department of Biomedical Sciences, University of Padova, Padova, Italy. .,Proteomics Center of Padova University, Padova, Italy.
| | - Giorgio Arrigoni
- Department of Biomedical Sciences, University of Padova, Padova, Italy. .,Proteomics Center of Padova University, Padova, Italy.
| | - Mariano Beltramini
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy.
| | - Luigi Bubacco
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy.
| | - Franco Onofri
- Department of Experimental Medicine, University of Genova, Genova, Italy.
| | - Giovanni Piccoli
- San Raffaele Scientific Park & University Vita-Salute San Raffaele, Milan, Italy. .,IN-CNR Milano, Milano, Italy.
| | - Elisa Greggio
- Department of Biology, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy.
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22
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Downregulated Expression of PTPN9 Contributes to Human Hepatocellular Carcinoma Growth and Progression. Pathol Oncol Res 2015; 22:555-65. [PMID: 26715439 DOI: 10.1007/s12253-015-0038-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 12/22/2015] [Indexed: 12/16/2022]
Abstract
Human hepatocellular carcinoma (HCC) is one of the most common malignant cancers, whose molecular mechanisms is remains largely. PTPN9 has recently been reported to play a critical role in breast cancer development. However, the role of PTPN9 in human HCC remains elusive. The present study aimed at investigating the potential role of PTPN9 in HCC. Western blot and immunohistochemistry were used to examine the expression of PTPN9 protein in HCC and adjacent non-tumorous tissues in 45 patients. Furthermore, Cell Counting Kit-8, flow cytometry and RNA interference experiments were performed to analyze the role of PTPN9 in the regulation of HCC cell proliferation. We showed that the expression level of PTPN9 was significantly reduced in HCC, compared with adjacent non-tumorous tissues. PTPN9 expression was inversely associated with Tumor size (P = 0.014), serum AFP level (P = 0.004) and Ki-67 expression. Low expression of PTPN9 predicted poor survival in HCC patients. Moreover, PTPN9 interference assay that PTPN9 inhibited cell proliferation in HepG2 cells. Cell apoptosis assay revealed that, silencing of PTPN9 expression significantly reduced cell apoptosis, compared with control ShRNA treatment group. Our results suggested that PTPN9 expression was down-regulated in HCC tumor tissues, and reduced PTPN9 expression was associated with worsened overall survival in HCC patients. Depletion of PTPN9 inhibits the apoptosis and promotes the proliferation of HCC cells.
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23
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Bu Y, Su F, Wang X, Gao H, Lei L, Chang N, Wu Q, Hu K, Zhu X, Chang Z, Meng K, Xiong JW. Protein tyrosine phosphatase PTPN9 regulates erythroid cell development through STAT3 dephosphorylation in zebrafish. J Cell Sci 2014; 127:2761-70. [PMID: 24727614 DOI: 10.1242/jcs.145367] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Protein tyrosine phosphatases (PTPs) are involved in hematopoiesis, but the function of many PTPs is not well characterized in vivo. Here, we have identified Ptpn9a, an ortholog of human PTPN9, as a crucial regulator of erythroid cell development in zebrafish embryos. ptpn9a, but not ptpn9b, was expressed in the posterior lateral plate mesoderm and intermediate cell mass - two primitive hematopoietic sites during zebrafish embryogenesis. Morpholino-mediated knockdown of ptpn9a caused erythrocytes to be depleted by inhibiting erythroid cell maturation without affecting erythroid proliferation and apoptosis. Consistently, both dominant-negative PTPN9 (with mutation C515S) and siRNA against PTPN9 inhibited erythroid differentiation in human K562 cells. Mechanistically, depletion of ptpn9 in zebrafish embryos in vivo or in K562 cells in vitro increased phosphorylated STAT3, and the hyper-phosphorylated STAT3 entrapped and prevented the transcription factors GATA1 and ZBP-89 (also known as ZNF148) from regulating erythroid gene expression. These findings imply that PTPN9 plays an important role in erythropoiesis by disrupting an inhibitory complex of phosphorylated STAT3, GATA1 and ZBP-89, providing new cellular and molecular insights into the role of ptpn9a in developmental hematopoiesis.
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Affiliation(s)
- Ye Bu
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, 100871 China
| | - Fuqin Su
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Medicine, School of Life Sciences, Tsinghua University, Beijing, 100084 China
| | - Xu Wang
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, 100871 China
| | - Hai Gao
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, 100871 China Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Beijing, 100094 China
| | - Lei Lei
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, 100871 China
| | - Nannan Chang
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, 100871 China
| | - Qing Wu
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, 100871 China
| | - Keping Hu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Beijing, 100094 China
| | - Xiaojun Zhu
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, 100871 China
| | - Zhijie Chang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Medicine, School of Life Sciences, Tsinghua University, Beijing, 100084 China
| | - Kun Meng
- Beijing Shenogen Biomedical Company Ltd, Beijing, 100085 China
| | - Jing-Wei Xiong
- Beijing Key Laboratory of Cardiometabolic Molecular Medicine and State Key Laboratory of Natural and Biomimetic Drugs, Institute of Molecular Medicine, Peking University, Beijing, 100871 China
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24
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Choi HW, Brooking-Dixon R, Neupane S, Lee CJ, Miao EA, Staats HF, Abraham SN. Salmonella typhimurium impedes innate immunity with a mast-cell-suppressing protein tyrosine phosphatase, SptP. Immunity 2014; 39:1108-20. [PMID: 24332031 DOI: 10.1016/j.immuni.2013.11.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 09/30/2013] [Indexed: 11/25/2022]
Abstract
The virulence of Salmonella is linked to its invasive capacity and suppression of adaptive immunity. This does not explain, however, the rapid dissemination of the pathogen after it breaches the gut. In our study, S. Typhimurium suppressed degranulation of local mast cells (MCs), resulting in limited neutrophil recruitment and restricting outflow of vascular contents into infection sites, thus facilitating bacterial spread. MC suppression was mediated by secreted effector protein (SptP), which shares structural homology with Yersinia YopH. SptP functioned by dephosphorylating the vesicle fusion protein N-ethylmalemide-sensitive factor and by blocking phosphorylation of Syk. Without SptP, orally challenged S. Typhimurium failed to suppress MC degranulation and exhibited limited colonization of the mesenteric lymph nodes. Administration of SptP to sites of E. coli infection markedly enhanced its virulence. Thus, SptP-mediated inactivation of local MCs is a powerful mechanism utilized by S. Typhimurium to impede early innate immunity.
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Affiliation(s)
- Hae Woong Choi
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
| | - Rhea Brooking-Dixon
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
| | - Subham Neupane
- Undergraduate Program in Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Chul-Jin Lee
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Edward A Miao
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Herman F Staats
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA; Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA; Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Soman N Abraham
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA; Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA; Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Program in Emerging Infectious Diseases, Duke - National University of Singapore Graduate Medical School, Singapore 169857, Singapore.
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25
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Shi L, Zhang Q, Xu B, Jiang X, Dai Y, Zhang CY, Zen K. Sustained high protein-tyrosine phosphatase 1B activity in the sperm of obese males impairs the sperm acrosome reaction. J Biol Chem 2014; 289:8432-41. [PMID: 24519936 DOI: 10.1074/jbc.m113.517466] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Evidence of a causal link between male obesity and subfertility or infertility has been demonstrated previously. However, the mechanism underlying this link is incompletely understood. Here, we report that sustained high protein-tyrosine phosphatase 1B (PTP1B) activity in sperm of obese donors plays an essential role in coupling male obesity and subfertility or infertility. First, PTP1B level and activity were significantly higher in sperm from ob/ob mice than in wild-type littermates. High PTP1B level and activity in sperm was also observed in obese patients compared with non-obese donors. The enhanced sperm PTP1B level and activity in ob/ob mice and obese patients correlated with a defect of the sperm acrosome reaction (AR). Second, treating sperm from male ob/ob mice or obese men with a specific PTP1B inhibitor largely restored the sperm AR. Finally, blockade of sperm AR by enhanced PTP1B activity in male ob/ob mice or obese men was due to prolonged dephosphorylation of N-ethylmaleimide-sensitive factor by PTP1B, leading to the inability to reassemble the trans-SNARE complexes, which is a critical step in sperm acrosomal exocytosis. In summary, our study demonstrates for the first time that a sustained high PTP1B level or activity in the sperm of obese donors causes a defect of sperm AR and that PTP1B is a novel potential therapeutic target for male infertility treatment.
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Affiliation(s)
- Lei Shi
- From the Jiangsu Engineering Research Center for MicroRNA Biology and Biotechnology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210093, China and
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26
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Nunes-Xavier CE, Martín-Pérez J, Elson A, Pulido R. Protein tyrosine phosphatases as novel targets in breast cancer therapy. Biochim Biophys Acta Rev Cancer 2013; 1836:211-26. [PMID: 23756181 DOI: 10.1016/j.bbcan.2013.06.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Accepted: 06/01/2013] [Indexed: 02/07/2023]
Abstract
Breast cancer is linked to hyperactivation of protein tyrosine kinases (PTKs), and recent studies have unveiled that selective tyrosine dephosphorylation by protein tyrosine phosphatases (PTPs) of specific substrates, including PTKs, may activate or inactivate oncogenic pathways in human breast cancer cell growth-related processes. Here, we review the current knowledge on the involvement of PTPs in breast cancer, as major regulators of breast cancer therapy-targeted PTKs, such as HER1/EGFR, HER2/Neu, and Src. The functional interplay between PTKs and PTK-activating or -inactivating PTPs, and its implications in novel breast cancer therapies based on targeting of specific PTPs, are discussed.
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Affiliation(s)
- Caroline E Nunes-Xavier
- BioCruces Health Research Institute, Hospital de Cruces, Plaza Cruces s/n, 48903 Barakaldo, Spain
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27
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Du WW, Fang L, Li M, Yang X, Liang Y, Peng C, Qian W, O'Malley YQ, Askeland RW, Sugg SL, Qian J, Lin J, Jiang Z, Yee AJ, Sefton M, Deng Z, Shan SW, Wang CH, Yang BB. MicroRNA miR-24 enhances tumor invasion and metastasis by targeting PTPN9 and PTPRF to promote EGF signaling. J Cell Sci 2013; 126:1440-53. [PMID: 23418360 DOI: 10.1242/jcs.118299] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
MicroRNAs are known to play regulatory roles in gene expression associated with cancer development. We analyzed levels of the microRNA miR-24 in patients with breast carcinoma and found that miR-24 was higher in breast carcinoma samples than in benign breast tissues. We generated constructs expressing miR-24 and studied its functions using both in vitro and in vivo techniques. We found that the ectopic expression of miR-24 promoted breast cancer cell invasion and migration. In vivo experiments in mice indicated that the expression of miR-24 enhanced tumor growth, invasion into local tissues, metastasis to lung tissues and decreased overall mouse survival. In the miR-24-expressing cells and tumors, EGFR was highly phosphorylated, whereas expression of the phosphatases tyrosine-protein phosphatase non-receptor type 9 (PTPN9) and receptor-type tyrosine-protein phosphatase F (PTPRF) were repressed. We confirmed that miR-24 could directly target both PTPN9 and PTPRF. Consistent with this, we found that the levels of phosphorylated epidermal growth factor receptor (pEGFR) were higher whereas the levels of PTPN9 and PTPRF were lower in the patients with metastatic breast carcinoma. Ectopic expression of PTPN9 and PTPRF decreased pEGFR levels, cell invasion, migration and tumor metastasis. Furthermore, we found that MMP2, MMP11, pErk, and ADAM15 were upregulated, whereas TIMP2 was downregulated; all of which supported the roles of miR-24 in tumor invasion and metastasis. Our results suggest that miR-24 plays a key role in breast cancer invasion and metastasis. miR-24 could potentially be a target for cancer intervention.
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Affiliation(s)
- William W Du
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, M4N 3M5, Canada
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28
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Stanford SM, Rapini N, Bottini N. Regulation of TCR signalling by tyrosine phosphatases: from immune homeostasis to autoimmunity. Immunology 2012; 137:1-19. [PMID: 22862552 DOI: 10.1111/j.1365-2567.2012.03591.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
More than half of the known protein tyrosine phosphatases (PTPs) in the human genome are expressed in T cells, and significant progress has been made in elucidating the biology of these enzymes in T-cell development and function. Here we provide a systematic review of the current understanding of the roles of PTPs in T-cell activation, providing insight into their mechanisms of action and regulation in T-cell receptor signalling, the phenotypes of their genetically modified mice, and their possible involvement in T-cell-mediated autoimmune disease. Our projection is that the interest in PTPs as mediators of T-cell homeostasis will continue to rise with further functional analysis of these proteins, and PTPs will be increasingly considered as targets of immunomodulatory therapies.
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Affiliation(s)
- Stephanie M Stanford
- Division of Cellular Biology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
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29
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Abstract
The striking morphology of the Golgi complex has fascinated cell biologists since its discovery over 100 years ago. Yet, despite intense efforts to understand how membrane flow relates to Golgi form and function, this organelle continues to baffle cell biologists and biochemists alike. Fundamental questions regarding Golgi function, while hotly debated, remain unresolved. Historically, Golgi function has been described from a protein-centric point of view, but we now appreciate that conceptual frameworks for how lipid metabolism is integrated with Golgi biogenesis and function are essential for a mechanistic understanding of this fascinating organelle. It is from a lipid-centric perspective that we discuss the larger question of Golgi dynamics and membrane trafficking. We review the growing body of evidence for how lipid metabolism is integrally written into the engineering of the Golgi system and highlight questions for future study.
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Affiliation(s)
- Vytas A Bankaitis
- Department of Cell and Developmental Biology, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA.
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30
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Muppirala M, Gupta V, Swarup G. Tyrosine phosphorylation of a SNARE protein, syntaxin 17: implications for membrane trafficking in the early secretory pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:2109-19. [PMID: 23006999 DOI: 10.1016/j.bbamcr.2012.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 09/13/2012] [Indexed: 10/27/2022]
Abstract
The T-cell protein tyrosine phosphatase is expressed as two splice variants - TC45, a nuclear protein, and TC48, which is localized predominantly in the ER (endoplasmic reticulum). Yeast two-hybrid screening revealed direct interaction of TC48 with Syntaxin17, a SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein localized predominantly in the ER and to some extent in the ER-Golgi intermediate compartment. Syntaxin 17 did not interact with TC45. C-terminal 40 amino acids of TC48 were sufficient for interaction with syntaxin 17. Overexpressed syntaxin 17 was phosphorylated at tyrosine upon pervanadate treatment (a tyrosine phosphatase inhibitor/tyrosine kinase activator) of COS-1 cells. Mutational analysis identified Tyr156 in the cytoplasmic domain as the major site of phosphorylation. Endogenous syntaxin 17 was phosphorylated by pervanadate treatment in CHO and MIN6 cells but was not phosphorylated in a variety of other cell lines tested. c-Abl was identified as one of the kinases, which phosphorylates syntaxin 17 in MIN6 cells. Phosphorylation of endogenous and overexpressed syntaxin 17 was reduced in the presence of IGF receptor and EGF receptor kinase inhibitors. Serum depletion reduced pervanadate-induced phosphorylation of endogenous syntaxin 17. TC48 coexpression reduced phosphorylation of syntaxin 17 by pervanadate and purified TC48 directly dephosphorylated syntaxin 17. β-COP dispersal by overexpressed syntaxin 17 was reduced after pervanadate-induced phosphorylation. A phospho-mimicking mutant (Y156E) of syntaxin 17 showed reduced interaction with COPI vesicles. These results suggest that tyrosine phosphorylation of syntaxin 17 is likely to have a role in regulating syntaxin 17 dependent membrane trafficking in the early secretory pathway.
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Affiliation(s)
- Madhavi Muppirala
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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31
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Labbé DP, Hardy S, Tremblay ML. Protein tyrosine phosphatases in cancer: friends and foes! PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 106:253-306. [PMID: 22340721 DOI: 10.1016/b978-0-12-396456-4.00009-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Tyrosine phosphorylation of proteins serves as an exquisite switch in controlling several key oncogenic signaling pathways involved in cell proliferation, apoptosis, migration, and invasion. Since protein tyrosine phosphatases (PTPs) counteract protein kinases by removing phosphate moieties on target proteins, one may intuitively think that PTPs would act as tumor suppressors. Indeed, one of the most described PTPs, namely, the phosphatase and tensin homolog (PTEN), is a tumor suppressor. However, a growing body of evidence suggests that PTPs can also function as potent oncoproteins. In this chapter, we provide a broad historical overview of the PTPs, their mechanism of action, and posttranslational modifications. Then, we focus on the dual properties of classical PTPs (receptor and nonreceptor) and dual-specificity phosphatases in cancer and summarize the current knowledge of the signaling pathways regulated by key PTPs in human cancer. In conclusion, we present our perspective on the potential of these PTPs to serve as therapeutic targets in cancer.
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Affiliation(s)
- David P Labbé
- Goodman Cancer Research Centre, McGill University, Montréal, Québec, Canada
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32
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Gómez CP, Tiemi Shio M, Duplay P, Olivier M, Descoteaux A. The protein tyrosine phosphatase SHP-1 regulates phagolysosome biogenesis. THE JOURNAL OF IMMUNOLOGY 2012; 189:2203-10. [PMID: 22826316 DOI: 10.4049/jimmunol.1103021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The process of phagocytosis and phagosome maturation involves the recruitment of effector proteins that participate in phagosome formation and in the acidification and/or fusion with various endocytic vesicles. In the current study, we investigated the role of the Src homology region 2 domain-containing phosphatase 1 (SHP-1) in phagolysosome biogenesis. To this end, we used immortalized bone marrow macrophages derived from SHP-1-deficient motheaten mice and their wild-type littermates. We found that SHP-1 is recruited early and remains present on phagosomes for up to 4 h postphagocytosis. Using confocal immunofluorescence microscopy and Western blot analyses on purified phagosome extracts, we observed an impaired recruitment of lysosomal-associated membrane protein 1 in SHP-1-deficient macrophages. Moreover, Western blot analyses revealed that whereas the 51-kDa procathepsin D is recruited to phagosomes, it is not processed into the 46-kDa cathepsin D in the absence of SHP-1, suggesting a defect in acidification. Using the lysosomotropic agent LysoTracker as an indicator of phagosomal pH, we obtained evidence that in the absence of SHP-1, phagosome acidification was impaired. Taken together, these results are consistent with a role for SHP-1 in the regulation of signaling or membrane fusion events involved in phagolysosome biogenesis.
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Affiliation(s)
- Carolina P Gómez
- Institut National de la Recherche Scientifique-Institut Armand-Frappier, Laval, Quebec H7V 1B7, Canada
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Lorentz A, Baumann A, Vitte J, Blank U. The SNARE Machinery in Mast Cell Secretion. Front Immunol 2012; 3:143. [PMID: 22679448 PMCID: PMC3367400 DOI: 10.3389/fimmu.2012.00143] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 05/17/2012] [Indexed: 11/13/2022] Open
Abstract
Mast cells are known as inflammatory cells which exert their functions in allergic and anaphylactic reactions by secretion of numerous inflammatory mediators. During an allergic response, the high-affinity IgE receptor, FcεRI, becomes cross-linked by receptor-bound IgE and antigen resulting in immediate release of pre-synthesized mediators – stored in granules – as well as in de novo synthesis of various mediators like cytokines and chemokines. Soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptors (SNARE) proteins were found to play a central role in regulating membrane fusion events during exocytosis. In addition, several accessory regulators like Munc13, Munc18, Rab GTPases, secretory carrier membrane proteins, complexins, or synaptotagmins were found to be involved in membrane fusion. In this review we summarize our current knowledge about the SNARE machinery and its mechanism of action in mast cell secretion.
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Affiliation(s)
- Axel Lorentz
- Department of Nutritional Medicine, University of Hohenheim Stuttgart, Germany
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34
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Su F, Ren F, Rong Y, Wang Y, Geng Y, Wang Y, Feng M, Ju Y, Li Y, Zhao ZJ, Meng K, Chang Z. Protein tyrosine phosphatase Meg2 dephosphorylates signal transducer and activator of transcription 3 and suppresses tumor growth in breast cancer. Breast Cancer Res 2012; 14:R38. [PMID: 22394684 PMCID: PMC3446372 DOI: 10.1186/bcr3134] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 11/15/2011] [Accepted: 03/06/2012] [Indexed: 12/21/2022] Open
Abstract
Introduction Signal transducer and activator of transcription 3 (STAT3) is over-activated or phosphorylated in breast cancers. The hyper-phosphorylation of STAT3 was attributed to either up-regulated phosphorylation by several tyrosine-kinases or down-regulated activity of phosphatases. Although several factors have been identified to phosphorylate STAT3, it remains unclear how STAT3 is dephosphorylated by PTPMeg2. The aim of this study was to determine the role of PTPMeg2 as a phosphatase in regulation of the activity of STAT3 in breast cancers. Methods Immunoprecipitation assays were used to study the interaction of STAT3 with PTPMeg2. A series of biochemistry experiments were performed to evaluate the role of PTPMeg2 in the dephosphorylation of STAT3. Two breast cancer cell lines MCF7 (PTPMeg2 was depleted as it was endogenously high) and MDA-MB-231 (PTPMeg2 was overexpressed as it was endogenously low) were used to compare the level of phosphorylated STAT3 and the tumor growth ability in vitro and in vivo. Samples from breast carcinoma (n = 73) were subjected to a pair-wise Pearson correlation analysis for the correlation of levels of PTPMeg2 and phosphorylated STAT3. Results PTPMeg2 directly interacts with STAT3 and mediates its dephosphorylation in the cytoplasm. Over-expression of PTPMeg2 decreased tyrosine phosphorylation of STAT3 while depletion of PTPMeg2 increased its phosphorylation. The decreased tyrosine phosphorylation of STAT3 is coupled with suppression of STAT3 transcriptional activity and reduced tumor growth in vitro and in vivo. Levels of PTPMeg2 and phosphorylated STAT3 were inversely correlated in breast cancer tissues (P = 0.004). Conclusions PTPMeg2 is an important phosphatase for the dephosphorylation of STAT3 and plays a critical role in breast cancer development.
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Affiliation(s)
- Fuqin Su
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Medicine, School of Life Sciences, Tsinghua University, Beijing 100084, China
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Sangwan V, Abella J, Lai A, Bertos N, Stuible M, Tremblay ML, Park M. Protein-tyrosine phosphatase 1B modulates early endosome fusion and trafficking of Met and epidermal growth factor receptors. J Biol Chem 2011; 286:45000-13. [PMID: 22045810 DOI: 10.1074/jbc.m111.270934] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The endoplasmic reticulum-localized non-receptor protein-tyrosine phosphatase 1B (PTP1B) is associated with oncogenic, metabolic, and cytokine-related signaling and functionally targets multiple receptor tyrosine kinases (RTKs) for dephosphorylation. Loss of PTP1B activity leads to enhanced ligand-dependent biological activity of the Met RTK among others. Here, we demonstrate that knockdown of PTP1B or expression of a PTP1B trapping aspartic acid-to-alanine substitution (D/A) mutant delayed ligand-induced degradation of the Met and EGF RTKs. Loss of PTP1B function abrogated trafficking of Met and EGF receptor to Rab5- and phosphatidylinositol 3-phosphate (Pl3P)-positive early endosomes and subsequent trafficking through the degradative pathway. Under these conditions, internalization of the Met and EGF receptors was unaltered, suggesting a block at the level of early endosome formation. We show that the N-ethylmaleimide-sensitive factor (NSF), an essential component of the vesicle fusion machinery, was hyperphosphorylated in PTP1B knockdown or PTP1B D/A-expressing cells and was a target for PTP1B. NSF knockdown phenocopied PTP1B knockdown, demonstrating a mechanism through which PTP1B regulates endocytic trafficking. Finally, we show that PTP1B dephosphorylated NSF and that this interaction was required for physiological RTK trafficking and appropriate attenuation of downstream signaling.
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Affiliation(s)
- Veena Sangwan
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A1, Canada
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Requirements for the catalytic cycle of the N-ethylmaleimide-Sensitive Factor (NSF). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1823:159-71. [PMID: 21689688 DOI: 10.1016/j.bbamcr.2011.06.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/23/2011] [Accepted: 06/06/2011] [Indexed: 12/23/2022]
Abstract
The N-ethylmaleimide-Sensitive Factor (NSF) was one of the initial members of the ATPases Associated with various cellular Activities Plus (AAA(+)) family. In this review, we discuss what is known about the mechanism of NSF action and how that relates to the mechanisms of other AAA(+) proteins. Like other family members, NSF binds to a protein complex (i.e., SNAP-SNARE complex) and utilizes ATP hydrolysis to affect the conformations of that complex. SNAP-SNARE complex disassembly is essential for SNARE recycling and sustained membrane trafficking. NSF is a homo-hexamer; each protomer is composed of an N-terminal domain, NSF-N, and two adjacent AAA-domains, NSF-D1 and NSF-D2. Mutagenesis analysis has established specific roles for many of the structural elements of NSF-D1, the catalytic ATPase domain, and NSF-N, the SNAP-SNARE binding domain. Hydrodynamic analysis of NSF, labeled with (Ni(2+)-NTA)(2)-Cy3, detected conformational differences in NSF, in which the ATP-bound conformation appears more compact than the ADP-bound form. This indicates that NSF undergoes significant conformational changes as it progresses through its ATP-hydrolysis cycle. Incorporating these data, we propose a sequential mechanism by which NSF uses NSF-N and NSF-D1 to disassemble SNAP-SNARE complexes. We also illustrate how analytical centrifugation might be used to study other AAA(+) proteins.
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Blank U. The mechanisms of exocytosis in mast cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 716:107-22. [PMID: 21713654 DOI: 10.1007/978-1-4419-9533-9_7] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Upon activation through high affinity IgE receptors (FcεRI), mast cells (MCs) can release up to 100% of their content of preformed mediators stored in cytoplasmic secretory granules by compound exocytosis. This causes Type I immediate hypersensitivity reactions and, in the case of inappropriate activation by allergens, the symptoms of allergy. Recent work has uncovered a central role of SNARE (Soluble N-ethylmaleimide-Sensitive Factor (NSF) Attachment Protein (SNAP) Receptors) proteins in regulating the numerous membrane fusion events during exocytosis. This has defined a series of new molecular actors in MC exocytosis that participate in the regulation of membrane fusion and the connection of the fusion machinery with early signaling events. The purpose of this chapter is to describe these proteins and provide a brief overview on their mechanism of action.
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Nile AH, Bankaitis VA, Grabon A. Mammalian diseases of phosphatidylinositol transfer proteins and their homologs. CLINICAL LIPIDOLOGY 2010; 5:867-897. [PMID: 21603057 PMCID: PMC3097519 DOI: 10.2217/clp.10.67] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Inositol and phosphoinositide signaling pathways represent major regulatory systems in eukaryotes. The physiological importance of these pathways is amply demonstrated by the variety of diseases that involve derangements in individual steps in inositide and phosphoinositide production and degradation. These diseases include numerous cancers, lipodystrophies and neurological syndromes. Phosphatidylinositol transfer proteins (PITPs) are emerging as fascinating regulators of phosphoinositide metabolism. Recent advances identify PITPs (and PITP-like proteins) to be coincidence detectors, which spatially and temporally coordinate the activities of diverse aspects of the cellular lipid metabolome with phosphoinositide signaling. These insights are providing new ideas regarding mechanisms of inherited mammalian diseases associated with derangements in the activities of PITPs and PITP-like proteins.
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Affiliation(s)
- Aaron H Nile
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
| | - Vytas A Bankaitis
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
| | - Aby Grabon
- Department of Cell & Developmental Biology, Lineberger Comprehensive Cancer Center School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-27090, USA
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Luerman GC, Powell DW, Uriarte SM, Cummins TD, Merchant ML, Ward RA, McLeish KR. Identification of phosphoproteins associated with human neutrophil granules following chemotactic peptide stimulation. Mol Cell Proteomics 2010; 10:M110.001552. [PMID: 21097543 DOI: 10.1074/mcp.m110.001552] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Regulated exocytosis of neutrophil intracellular storage granules is necessary for neutrophil participation in the inflammatory response. The signal transduction pathways that participate in neutrophil exocytosis are complex and poorly defined. Several protein kinases, including p38 MAPK and the nonreceptor tyrosine kinases, Hck and Fgr, participate in this response. However, the downstream targets of these kinases that regulate exocytosis are unknown. The present study combined a novel inhibitor of neutrophil exocytosis with proteomic techniques to identify phosphopeptides and phosphoproteins from a population of gelatinase and specific granules isolated from unstimulated and fMLF-stimulated neutrophils. To prevent loss of granule-associated phosphoproteins upon exocytosis, neutrophils were pretreated with a TAT-fusion protein containing a SNARE domain from SNAP-23 (TAT-SNAP-23), which inhibited fMLF-stimulated CD66b-containing granule exocytosis by 100±10%. Following TAT-SNAP-23 pretreatment, neutrophils were stimulated with the chemotactic peptide fMLF for 0 min, 1 min, and 2 min. Granules were isolated by gradient centrifugation and subjected to proteolytic digestion with trypsin or chymotrypsin to obtain peptides from the outer surface of the granule. Phosphopeptides were enriched by gallium or TiO2 affinity chromatography, and phosphopeptides and phosphorylation sites were identified by reversed phase high performance liquid chromatography-electrospray ionization-tandem MS. This resulted in the identification of 243 unique phosphopeptides corresponding to 235 proteins, including known regulators of vesicle trafficking. The analysis identified 79 phosphoproteins from resting neutrophils, 81 following 1 min of fMLF stimulation, and 118 following 2 min of stimulation. Bioinformatic analysis identified a potential Src tyrosine kinase motif from a phosphopeptide corresponding to G protein coupled receptor kinase 5 (GRK5). Phosphorylation of GRK5 by Src was confirmed by an in vitro kinase reaction and by precursor ion scanning for phospho-tyrosine specific immonium ions containing Tyr251 and Tyr253. Immunoprecipitation of phosphorylated GRK5 from intact cells was reduced by a Src inhibitor. In conclusion, targets of signal transduction pathways were identified that are candidates to regulate neutrophil granule exocytosis.
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Affiliation(s)
- Gregory C Luerman
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, KY 40202, USA
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41
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Hemmerling J, Nell S, Kipp A, Schumann S, Deubel S, Haack M, Brigelius-Flohé R. alpha-Tocopherol enhances degranulation in RBL-2H3 mast cells. Mol Nutr Food Res 2010; 54:652-60. [PMID: 20169586 DOI: 10.1002/mnfr.200900462] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Based on the observation that 3 months alpha-tocopherol supplementation caused an up-regulation of the mRNA of vesicular transport proteins in livers of mice, the functional relevance was investigated in RBL-2H3 cells, a model for mast cell degranulation. In total, 24 h incubation with 100 muM alpha-tocopherol enhanced the basal and phorbol-12-myristyl-13-acetate/ionomycin-stimulated release of beta-hexosaminidase and cathepsin D as measured by enzymatic analysis as well as Western blotting and immunocytochemistry, respectively. beta-Tocopherol exerted the same effect, whereas alpha-tocopheryl phosphate and trolox were inactive, indicating that both the side chain and the 6-OH group at the chroman ring are essential for activation of degranulation. alpha-Tocopherol did not induce mRNA expression of soluble NSF-attachment protein receptor (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) proteins, such as N-ethylmaleimide sensitive fusion protein, complexin-2, SNAP23 or syntaxin-3, in the RBL-2H3 cell model. In view of the well known alpha-tocopherol-mediated activation of protein phosphatases, which regulate soluble NSF-attachment protein receptor activities by dephosphorylation, underlying mechanisms are discussed in terms of preventing oxidative inactivation of protein phosphatases and so far unknown functions in certain membrane domains.
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Affiliation(s)
- Jana Hemmerling
- German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany
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Thareja S, Aggarwal S, Bhardwaj TR, Kumar M. Protein Tyrosine Phosphatase 1B Inhibitors: A Molecular Level Legitimate Approach for the Management of Diabetes Mellitus. Med Res Rev 2010; 32:459-517. [DOI: 10.1002/med.20219] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Suresh Thareja
- University Institute of Pharmaceutical Sciences; Panjab University; 160 014; Chandigarh; India
| | - Saurabh Aggarwal
- University Institute of Pharmaceutical Sciences; Panjab University; 160 014; Chandigarh; India
| | | | - Manoj Kumar
- University Institute of Pharmaceutical Sciences; Panjab University; 160 014; Chandigarh; India
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Visual Arrestin 1 acts as a modulator for N-ethylmaleimide-sensitive factor in the photoreceptor synapse. J Neurosci 2010; 30:9381-91. [PMID: 20631167 DOI: 10.1523/jneurosci.1207-10.2010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the G-protein-coupled receptor phototransduction cascade, visual Arrestin 1 (Arr1) binds to and deactivates phosphorylated light-activated opsins, a process that is critical for effective recovery and normal vision. In this report, we discovered a novel synaptic interaction between Arr1 and N-ethylmaleimide-sensitive factor (NSF) that is enhanced in a dark environment when mouse photoreceptors are depolarized and the rate of exocytosis is elevated. In the photoreceptor synapse, NSF functions to sustain a higher rate of exocytosis, in addition to the compensatory endocytosis to retrieve and to recycle vesicle membrane and synaptic proteins. Not only does Arr1 bind to the junction of NSF N-terminal and its first ATPase domains in an ATP-dependent manner in vitro, but Arr1 also enhances both NSF ATPase and NSF disassembly activities. In in vivo experiments in mouse retinas with the Arr1 gene knocked out, the expression levels of NSF and other synapse-enriched components, including vGLUT1 (vesicular glutamate transporter 1), EAAT5 (excitatory amino acid transporter 5), and VAMP2 (vesicle-associated membrane protein 2), are markedly reduced, which leads to a substantial decrease in the exocytosis rate with FM1-43. Thus, we propose that the Arr1 and NSF interaction is important for modulating normal synaptic function in mouse photoreceptors. This study demonstrates a vital alternative function for Arr1 in the photoreceptor synapse and provides key insights into the potential molecular mechanisms of inherited retinal diseases, such as Oguchi disease and Arr1-associated retinitis pigmentosa.
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Yuan T, Wang Y, Zhao ZJ, Gu H. Protein-tyrosine phosphatase PTPN9 negatively regulates ErbB2 and epidermal growth factor receptor signaling in breast cancer cells. J Biol Chem 2010; 285:14861-14870. [PMID: 20335174 DOI: 10.1074/jbc.m109.099879] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
ErbB family of the receptor protein-tyrosine kinase plays an important role in the progression of human cancers including breast cancer. Finding protein-tyrosine phosphatase (PTPs) that can specifically regulate the function of ErbB should help design novel therapies for treatment. By performing a small interfering RNA screen against 43 human PTPs, we find that knockdown of protein-tyrosine phosphatase PTPN9 significantly increases ErbB2 tyrosyl phosphorylation in the SKBR3 breast cancer cell line. In addition, knockdown of PTPN9 expression also enhances tyrosyl phosphorylation of the ErbB1/epidermal growth factor receptor (EGFR) in the MDA-MB-231 breast cancer cell line. Conversely, increasing expression of PTPN9 wild type (WT) inhibits tyrosyl phosphorylation of ErbB2 and EGFR. To test whether ErbB2 and EGFR are substrates of PTPN9, PTPN9 WT, and a substrate trapping mutant (PTPN9 DA) are overexpressed in SKBR3 and MDA-MB-231 cells. Compared with vector control, expression of PTPN9 WT significantly inhibits whereas expression of PTPN9 DA dramatically enhances tyrosyl phosphorylation of ErbB2 and EGFR, respectively. In contrast, expression of PTPN9 WT or DA mutant does not affect tyrosyl phosphorylation of ErbB3 and Shc. Importantly, coimmunoprecipitation and glutathione S-transferase fusion protein pulldown experiments show that tyrosol-phosphorylated ErbB2 or EGFR is preferentially associated with PTPN9 DA compared with PTPN9 WT, indicating that ErbB2 and EGFR are substrates of PTPN9. Furthermore, PTPN9 WT expression specifically impairs EGF-induced STAT3 and STAT5 activation, and inhibits the cell growth in soft agar. Last, PTPN9 WT expression also reduces invasion and MMP2 expression of MDA-MB-231 cells. Our data suggest PTPN9 as a negative regulator of breast cancer cells by targeting ErbB2 and EGFR and inhibiting STAT activation.
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Affiliation(s)
- Taichang Yuan
- Department of Pathology, University of Colorado, Denver, Health Science Center, Aurora, Colorado 80045
| | - Yongping Wang
- Department of Pathology, University of Colorado, Denver, Health Science Center, Aurora, Colorado 80045
| | - Zhizhuang J Zhao
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Haihua Gu
- Department of Pathology, University of Colorado, Denver, Health Science Center, Aurora, Colorado 80045.
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45
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Thielmann Y, Weiergräber OH, Ma P, Schwarten M, Mohrlüder J, Willbold D. Comparative modeling of human NSF reveals a possible binding mode of GABARAP and GATE-16. Proteins 2010; 77:637-46. [PMID: 19533740 DOI: 10.1002/prot.22477] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Vesicular trafficking is an important homeostatic process in eukaryotic cells which critically relies on membrane fusion. One of the essential components of the universal membrane fusion machinery is NSF (N-ethylmaleimide-sensitive factor), a large hexameric ATPase involved in disassembly of SNARE (soluble NSF attachment protein receptor) complexes. To improve our understanding of this sophisticated molecular machine, we have modeled the structure of the NSF hexamer in two alternative assemblies. Our data suggest a mechanistic concept of the operating mode of NSF which helps to explain the functional impact of post-translational modifications and mutations reported previously. Furthermore, we propose a binding site for the ubiquitin-like proteins GABARAP and GATE-16, which is supported by experimental evidence, yielding a complex with favorable surface complementarity.
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Affiliation(s)
- Yvonne Thielmann
- Institut für Strukturbiologie und Biophysik 3 (Strukturbiochemie), Forschungszentrum Jülich, 52425 Jülich, Germany
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Zhao C, Matveeva EA, Ren Q, Whiteheart SW. Dissecting the N-ethylmaleimide-sensitive factor: required elements of the N and D1 domains. J Biol Chem 2009; 285:761-72. [PMID: 19887446 DOI: 10.1074/jbc.m109.056739] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
N-Ethylmaleimide-sensitive factor (NSF) is a homo-hexameric member of the AAA(+) (ATPases associated with various cellular activities plus) family. It plays an essential role in most intracellular membrane trafficking through its binding to and disassembly of soluble NSF attachment protein (SNAP) receptor (SNARE) complexes. Each NSF protomer contains an N-terminal domain (NSF-N) and two AAA domains, a catalytic NSF-D1 and a structural NSF-D2. This study presents detailed mutagenesis analyses of NSF-N and NSF-D1, dissecting their roles in ATP hydrolysis, SNAP.SNARE binding, and complex disassembly. Our results show that a positively charged surface on NSF-N, bounded by Arg(67) and Lys(105), and the conserved residues in the central pore of NSF-D1 (Tyr(296) and Gly(298)) are involved in SNAP.SNARE binding but not basal ATP hydrolysis. Mutagenesis of Sensor 1 (Thr(373)-Arg(375)), Sensor 2 (Glu(440)-Glu(442)), and Arginine Fingers (Arg(385) and Arg(388)) in NSF-D1 shows that each region plays a discrete role. Sensor 1 is important for basal ATPase activity and nucleotide binding. Sensor 2 plays a role in ATP- and SNAP-dependent SNARE complex binding and disassembly but does so in cis and not through inter-protomer interactions. Arginine Fingers are important for SNAP.SNARE complex-stimulated ATPase activity and complex disassembly. Mutants at these residues have a dominant-negative phenotype in cells, suggesting that Arginine Fingers function in trans via inter-protomer interactions. Taken together, these data establish functional roles for many of the structural elements of the N domain and of the D1 ATP-binding site of NSF.
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Affiliation(s)
- Chunxia Zhao
- Department of Molecular and Cellular Biochemistry, University of Kentucky Medical Center, Lexington, Kentucky 40536-0509, USA
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Gonçalves JP, Grãos M, Valente AX. POLAR MAPPER: a computational tool for integrated visualization of protein interaction networks and mRNA expression data. J R Soc Interface 2009; 6:881-96. [PMID: 19091689 PMCID: PMC2684442 DOI: 10.1098/rsif.2008.0407] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Accepted: 11/04/2008] [Indexed: 11/25/2022] Open
Abstract
Polar Mapper is a computational application for exposing the architecture of protein interaction networks. It facilitates the system-level analysis of mRNA expression data in the context of the underlying protein interaction network. Preliminary analysis of a human protein interaction network and comparison of the yeast oxidative stress and heat shock gene expression responses are addressed as case studies.
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Affiliation(s)
- Joana P. Gonçalves
- Unidade de Sistemas Biológicos, Biocant, 3060-197 Cantanhede, Portugal
- KDBIO Group, INESC-ID, 1000-029 Lisbon, Portugal
- IST, Technical University of Lisbon, 1169-047 Lisbon, Portugal
| | - Mário Grãos
- Unidade de Biologia Celular, Biocant, 3060-197 Cantanhede, Portugal
| | - André X.C.N. Valente
- Unidade de Sistemas Biológicos, Biocant, 3060-197 Cantanhede, Portugal
- Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004-517 Coimbra, Portugal
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Mohrlüder J, Schwarten M, Willbold D. Structure and potential function of gamma-aminobutyrate type A receptor-associated protein. FEBS J 2009; 276:4989-5005. [PMID: 19674112 DOI: 10.1111/j.1742-4658.2009.07207.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The gamma-aminobutyrate type A receptor-associated protein (GABARAP) is a ubiquitin-like modifier, and is implicated in a variety of membrane trafficking and fusion events that are crucial to synaptic plasticity, autophagy and apoptosis. However, important aspects of GABARAP function and regulation remain poorly understood. We review the current state of knowledge about GABARAP, highlighting newly-identified GABARAP ligands, and discuss the possible physiological relevance of each ligand interaction.
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Affiliation(s)
- Jeannine Mohrlüder
- Institut für Strukturbiologie und Biophysik (ISB-3), Forschungszentrum Jülich, Germany.
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Nell S, Bahtz R, Bossecker A, Kipp A, Landes N, Bumke-Vogt C, Halligan E, Lunec J, Brigelius-Flohé R. PCR-verified microarray analysis and functionalin vitrostudies indicate a role of α-tocopherol in vesicular transport. Free Radic Res 2009; 41:930-42. [PMID: 17654050 DOI: 10.1080/10715760701416988] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Global gene expression profiles of livers from mice, fed diets differing in alpha-tocopherol content, were compared using DNA microarray technology. Three hundred and eighty nine genes were found to significantly differ in their expression level by a factor of 2 or higher between the high and the low alpha-tocopherol group. Functional clustering using the EASE software identified 121 genes involved in transport processes. Twenty-one thereof were involved in (synaptic) vesicular trafficking. Up-regulation of syntaxin 1C (Stx1c), vesicle-associated membrane protein 1 (Vamp1), N-ethylmaleimide-sensitive factor (Nsf) and syntaxin binding protein 1 (Stxbp1, Munc18-1) was verified by real time PCR. At a functional level, alpha-tocopherol increased the secretory response in RBL and PC12 cells. Although here detected in liver, the alpha-tocopherol-responsive pathways are also relevant to neurotransmission. A role of alpha-tocopherol in the vesicular transport might not only affect its own absorption and transport but also explain the neural dysfunctions observed in severe alpha-tocopherol deficiency.
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Affiliation(s)
- Sandra Nell
- German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal, Germany
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50
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Branham MT, Bustos MA, De Blas GA, Rehmann H, Zarelli VEP, Treviño CL, Darszon A, Mayorga LS, Tomes CN. Epac activates the small G proteins Rap1 and Rab3A to achieve exocytosis. J Biol Chem 2009; 284:24825-39. [PMID: 19546222 DOI: 10.1074/jbc.m109.015362] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Exocytosis of the acrosome (the acrosome reaction) relies on cAMP production, assembly of a proteinaceous fusion machinery, calcium influx from the extracellular medium, and mobilization from inositol 1,4,5-trisphosphate-sensitive intracellular stores. Addition of cAMP to human sperm suspensions bypasses some of these requirements and elicits exocytosis in a protein kinase A- and extracellular calcium-independent manner. The relevant cAMP target is Epac, a guanine nucleotide exchange factor for the small GTPase Rap. We show here that a soluble adenylyl cyclase synthesizes the cAMP required for the acrosome reaction. Epac stimulates the exchange of GDP for GTP on Rap1, upstream of a phospholipase C. The Epac-selective cAMP analogue 8-pCPT-2'-O-Me-cAMP induces a phospholipase C-dependent calcium mobilization in human sperm suspensions. In addition, our studies identify a novel connection between cAMP and Rab3A, a secretory granule-associated protein, revealing that the latter functions downstream of soluble adenylyl cyclase/cAMP/Epac but not of Rap1. Challenging sperm with calcium or 8-pCPT-2'-O-Me-cAMP boosts the exchange of GDP for GTP on Rab3A. Recombinant Epac does not release GDP from Rab3A in vitro, suggesting that the Rab3A-GEF activation by cAMP/Epac in vivo is indirect. We propose that Epac sits at a critical point during the exocytotic cascade after which the pathway splits into two limbs, one that assembles the fusion machinery into place and another that elicits intracellular calcium release.
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Affiliation(s)
- María T Branham
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología-Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, CC 56, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
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