1
|
Hsu MF, Koike S, Chen CS, Najjar SM, Meng TC, Haj FG. Pharmacological inhibition of the Src homology phosphatase 2 confers partial protection in a mouse model of alcohol-associated liver disease. Biomed Pharmacother 2024; 175:116590. [PMID: 38653109 DOI: 10.1016/j.biopha.2024.116590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 04/06/2024] [Accepted: 04/10/2024] [Indexed: 04/25/2024] Open
Abstract
Alcohol-associated liver disease (ALD) is a leading factor of liver-related death worldwide. ALD has various manifestations that include steatosis, hepatitis, and cirrhosis and is currently without approved pharmacotherapies. The Src homology phosphatase 2 (Shp2) is a drug target in some cancers due to its positive regulation of Ras-mitogen-activated protein kinase signaling and cell proliferation. Shp2 pharmacological inhibition yields beneficial outcomes in animal disease models, but its impact on ALD remains unexplored. This study aims to investigate the effects of Shp2 inhibition and its validity using a preclinical mouse model of ALD. We report that the administration of SHP099, a potent and selective allosteric inhibitor of Shp2, partially ameliorated ethanol-induced hepatic injury, inflammation, and steatosis in mice. Additionally, Shp2 inhibition was associated with reduced ethanol-evoked activation of extracellular signal-regulated kinase (ERK), oxidative, and endoplasmic reticulum (ER) stress in the liver. Besides the liver, excessive alcohol consumption induces multi-organ injury and dysfunction, including the intestine. Notably, Shp2 inhibition diminished ethanol-induced intestinal inflammation and permeability, abrogated the reduction in tight junction protein expression, and the activation of ERK and stress signaling in the ileum. Collectively, Shp2 pharmacological inhibition mitigates the deleterious effects of ethanol in the liver and intestine in a mouse model of ALD. Given the multifactorial aspects underlying ALD pathogenesis, additional studies are needed to decipher the utility of Shp2 inhibition alone or as a component in a multitherapeutic regimen to combat this deadly malady.
Collapse
Affiliation(s)
- Ming-Fo Hsu
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, USA.
| | - Shinichiro Koike
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Chang-Shan Chen
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
| | - Sonia M Najjar
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA; Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
| | - Fawaz G Haj
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, USA; Comprehensive Cancer Center, University of California Davis, Sacramento, CA 95817, USA; Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, University of California Davis, Sacramento, CA 95817, USA.
| |
Collapse
|
2
|
Hsu MF, Ito Y, Singh JP, Hsu SF, Wells A, Jen KY, Meng TC, Haj FG. Protein tyrosine phosphatase 1B is a regulator of alpha-actinin4 in the glomerular podocyte. Biochim Biophys Acta Mol Cell Res 2024; 1871:119590. [PMID: 37730132 PMCID: PMC11060668 DOI: 10.1016/j.bbamcr.2023.119590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 09/12/2023] [Accepted: 09/14/2023] [Indexed: 09/22/2023]
Abstract
Glomerular podocytes are instrumental for the barrier function of the kidney, and podocyte injury contributes to proteinuria and the deterioration of renal function. Protein tyrosine phosphatase 1B (PTP1B) is an established metabolic regulator, and the inactivation of this phosphatase mitigates podocyte injury. However, there is a paucity of data regarding the substrates that mediate PTP1B actions in podocytes. This study aims to uncover novel substrates of PTP1B in podocytes and validate a leading candidate. To this end, using substrate-trapping and mass spectroscopy, we identified putative substrates of this phosphatase and investigated the actin cross-linking cytoskeletal protein alpha-actinin4. PTP1B and alpha-actinin4 co-localized in murine and human glomeruli and transiently transfected E11 podocyte cells. Additionally, podocyte PTP1B deficiency in vivo and culture was associated with elevated tyrosine phosphorylation of alpha-actinin4. Conversely, reconstitution of the knockdown cells with PTP1B attenuated alpha-actinin4 tyrosine phosphorylation. We demonstrated co-association between alpha-actinin4 and the PTP1B substrate-trapping mutant, which was enhanced upon insulin stimulation and disrupted by vanadate, consistent with an enzyme-substrate interaction. Moreover, we identified alpha-actinin4 tandem tyrosine residues 486/487 as mediators of its interaction with PTP1B. Furthermore, knockdown studies in E11 cells suggest that PTP1B and alpha-actinin4 are modulators of podocyte motility. These observations indicate that PTP1B and alpha-actinin4 are likely interacting partners in a signaling node that modulates podocyte function. Targeting PTP1B and plausibly this one of its substrates may represent a new therapeutic approach for podocyte injury that warrants additional investigation.
Collapse
Affiliation(s)
- Ming-Fo Hsu
- Department of Nutrition, University of California Davis, Davis, CA, USA
| | - Yoshihiro Ito
- Department of Nutrition, University of California Davis, Davis, CA, USA
| | - Jai Prakash Singh
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
| | - Shu-Fang Hsu
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
| | - Alan Wells
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Kuang-Yu Jen
- Department of Pathology and Laboratory Medicine, University of California Davis, Sacramento, CA, USA
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
| | - Fawaz G Haj
- Department of Nutrition, University of California Davis, Davis, CA, USA; Comprehensive Cancer Center, University of California Davis, Sacramento, CA, USA; Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, University of California Davis, Sacramento, CA, USA.
| |
Collapse
|
3
|
Chien YC, Wang YS, Sridharan D, Kuo CW, Chien CT, Uchihashi T, Kato K, Angata T, Meng TC, Hsu STD, Khoo KH. High Density of N- and O-Glycosylation Shields and Defines the Structural Dynamics of the Intrinsically Disordered Ectodomain of Receptor-type Protein Tyrosine Phosphatase Alpha. JACS Au 2023; 3:1864-1875. [PMID: 37502146 PMCID: PMC10369406 DOI: 10.1021/jacsau.3c00124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/01/2023] [Accepted: 06/01/2023] [Indexed: 07/29/2023]
Abstract
The intracellular phosphatase domain of the receptor-type protein tyrosine phosphatase alpha (PTPRA) is known to regulate various signaling pathways related to cell adhesion through c-Src kinase activation. In contrast, the functional significance of its relatively short, intrinsically disordered, and heavily glycosylated ectodomain remains unclear. Through detailed mass spectrometry analyses of a combination of protease and glycosidase digests, we now provide the first experimental evidence for its site-specific glycosylation pattern. This includes the occurrence of O-glycan at the N-glycosylation sequon among the more than 30 O-glycosylation sites confidently identified beside the 7 N-glycosylation sites. The closely spaced N- and O-glycans appear to have mutually limited the extent of further galactosylation and sialylation. An immature smaller form of full-length PTPRA was found to be deficient in O-glycosylation, most likely due to failure to transit the Golgi. N-glycosylation, on the other hand, is dispensable for cell surface expression and contributes less than the extensive O-glycosylation to the overall solution structure of the ectodomain. The glycosylation information is combined with the overall structural features of the ectodomain derived from small-angle X-ray scattering and high-speed atomic force microscopy monitoring to establish a dynamic structural model of the densely glycosylated PTPRA ectodomain. The observed high structural flexibility, as manifested by continuous transitioning from fully to partially extended and fold-back conformations, suggests that the receptor-type phosphatase is anchored to the membrane and kept mostly at a monomeric state through an ectodomain shaped and fully shielded by glycosylation.
Collapse
Affiliation(s)
- Yu-Chun Chien
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
| | - Yong-Sheng Wang
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
| | - Deepa Sridharan
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Chu-Wei Kuo
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Chih-Ta Chien
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Takayuki Uchihashi
- Department
of Physics, Nagoya University, Nagoya 464-8602, Japan
- Exploratory
Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
| | - Koichi Kato
- Exploratory
Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
- Institute
for Molecular Science, National Institutes
of Natural Sciences, Okazaki 444-8787, Japan
- Graduate
School of Pharmaceutical Sciences, Nagoya
City University, Nagoya 467-8603, Japan
| | - Takashi Angata
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
| | - Tzu-Ching Meng
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
| | - Shang-Te Danny Hsu
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
- International
Institute for Sustainability with Knotted Chiral Meta Matter, Hiroshima University, Higashihiroshima 739-8527, Japan
| | - Kay-Hooi Khoo
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
- Exploratory
Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
| |
Collapse
|
4
|
Singh JP, Chen YY, Huang YT, Hsu STD, Meng TC. Application of hybrid biophysical-biochemical methods to unravel the molecular basis for auto-inhibition and activation of protein tyrosine phosphatase TCPTP/PTPN2. Methods Enzymol 2023; 682:351-374. [PMID: 36948707 DOI: 10.1016/bs.mie.2022.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Since the discovery of protein tyrosine phosphorylation as one of the critical post-translational modifications, it has been well known that the activity of protein tyrosine kinases (PTKs) is tightly regulated. On the other hand, protein tyrosine phosphatases (PTPs) are often regarded to act constitutively active, but recently we and others have shown that many PTPs are expressed in an inactive form due to allosteric inhibition by their unique structural features. Furthermore, their cellular activity is highly regulated in a spatiotemporal manner. In general, PTPs share a conserved catalytic domain comprising about 280 residues that is flanked by either an N-terminal or a C-terminal non-catalytic segment, which differs significantly in size and structure from each other and is known to regulate specific PTP's catalytic activity. The well-characterized non-catalytic segments can be globular or intrinsically disordered. In this work, we have focused on the T-Cell Protein Tyrosine Phosphatase (TCPTP/PTPN2) and demonstrated how the hybrid biophysical-biochemical methods can be applied to unravel the underlying mechanism through which TCPTP's catalytic activity is regulated by the non-catalytic C-terminal segment. Our analysis showed that TCPTP is auto-inhibited by its intrinsically disordered tail and trans-activated by Integrin alpha-1's cytosolic region.
Collapse
Affiliation(s)
| | - Yi-Yun Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Academia Sinica Common Mass Spectrometry Facilities for Proteomics and Protein Modification Analysis, Taipei, Taiwan
| | - Yu-Ting Huang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
| |
Collapse
|
5
|
Yang CY, Yang CF, Tang XF, Machado LESF, Singh JP, Peti W, Chen CS, Meng TC. Active-site cysteine 215 sulfonation targets protein tyrosine phosphatase PTP1B for Cullin1 E3 ligase-mediated degradation. Free Radic Biol Med 2023; 194:147-159. [PMID: 36462629 DOI: 10.1016/j.freeradbiomed.2022.11.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/14/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022]
Abstract
Reactive oxygen species (ROS), released as byproducts of mitochondrial metabolism or as products of NADPH oxidases and other processes, can directly oxidize the active-site cysteine (Cys) residue of protein tyrosine phosphatases (PTPs) in a mammalian cell. Robust degradation of irreversibly oxidized PTPs is essential for preventing accumulation of these permanently inactive enzymes. However, the mechanism underlying the degradation of these proteins was unknown. In this study, we found that the active-site Cys215 of endogenous PTP1B is sulfonated in H9c2 cardiomyocytes under physiological conditions. The sulfonation of Cys215 led PTP1B to exhibit a conformational change, and drive the subsequent ubiquitination and degradation of this protein. We then discovered that Cullin1, an E3 ligase, interacts with the Cys215-sulfonated PTP1B. The functional impairment of Cullin1 prevented PTP1B from oxidation-dependent ubiquitination and degradation in H9c2 cells. Moreover, delivery of the terminally oxidized PTP1B resulted in proteotoxicity-caused injury in the affected cells. In conclusion, we elucidate how sulfonation of the active-site Cys215 can direct turnover of endogenous PTP1B through the engagement of ubiquitin-proteasome system. These data highlight a novel mechanism that maintains PTP homeostasis in cardiomyocytes with constitutive ROS production.
Collapse
Affiliation(s)
- Chun-Yi Yang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, 115, Taiwan
| | - Chiu-Fen Yang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan; Department of Cardiology, Cardiovascular Research Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, 970, Taiwan
| | - Xiao-Fang Tang
- Graduate Institute of Systems Biology and Bioinformatics, National Central University, 300 Jhongda Road, Jhongli, 320, Taiwan
| | - Luciana E S F Machado
- Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo, SP, 05508-090, Brazil
| | - Jai Prakash Singh
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan
| | - Wolfgang Peti
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Chien-Sheng Chen
- Graduate Institute of Systems Biology and Bioinformatics, National Central University, 300 Jhongda Road, Jhongli, 320, Taiwan; Department of Biomedical Science and Engineering, National Central University, Jongli District, Taoyuan City, 32001, Taiwan; Department of Food Safety / Hygiene and Risk Management, National Cheng Kung University, Tainan, Taiwan
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, 115, Taiwan.
| |
Collapse
|
6
|
Singh JP, Lin MJ, Hsu SF, Peti W, Lee CC, Meng TC. Crystal Structure of TCPTP Unravels an Allosteric Regulatory Role of Helix α7 in Phosphatase Activity. Biochemistry 2021; 60:3856-3867. [PMID: 34910875 DOI: 10.1021/acs.biochem.1c00519] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The T-cell protein tyrosine phosphatase (TCPTP/PTPN2) targets a broad variety of substrates across different subcellular compartments. In spite of that, the structural basis for the regulation of TCPTP's activity remains elusive. Here, we investigated whether the activity of TCPTP is regulated by a potential allosteric site in a comparable manner to its most similar PTP family member (PTP1B/PTPN1). We determined two crystal structures of TCPTP at 1.7 and 1.9 Å resolutions that include helix α7 at the TCPTP C-terminus. Helix α7 has been functionally characterized in PTP1B and was identified as its allosteric switch. However, its function is unknown in TCPTP. Here, we demonstrate that truncation or deletion of helix α7 reduced the catalytic efficiency of TCPTP by ∼4-fold. Collectively, our data supports an allosteric role of helix α7 in regulation of TCPTP's activity, similar to its function in PTP1B, and highlights that the coordination of helix α7 with the core catalytic domain is essential for the efficient catalytic function of TCPTP.
Collapse
Affiliation(s)
- Jai Prakash Singh
- Institute of Biological Chemistry, Academia Sinica, 128, Academia Road Sec. 2, Nankang, Taipei 115, Taiwan.,Chemical Biology and Molecular Biophysics, Taiwan International Graduate Program, Academia Sinica, 128, Academia Road Sec. 2, Nankang, Taipei 115, Taiwan.,Department of Chemistry, National Tsing Hua University, 101, Kuang-Fu Road, Sec. 2, Hsinchu 300, Taiwan
| | - Meng-Jung Lin
- Institute of Biological Chemistry, Academia Sinica, 128, Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Shu-Fang Hsu
- Institute of Biological Chemistry, Academia Sinica, 128, Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Wolfgang Peti
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut 06030, United States
| | - Cheng-Chung Lee
- Institute of Biological Chemistry, Academia Sinica, 128, Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, 128, Academia Road Sec. 2, Nankang, Taipei 115, Taiwan.,Chemical Biology and Molecular Biophysics, Taiwan International Graduate Program, Academia Sinica, 128, Academia Road Sec. 2, Nankang, Taipei 115, Taiwan.,Institute of Biochemical Sciences, National Taiwan University, 1 Roosevelt Road Sec. 4, Taipei 106, Taiwan
| |
Collapse
|
7
|
Chen YJ, Liu YC, Liu YW, Lee YB, Huang HC, Chen YY, Shih YH, Lee YC, Cheng CF, Meng TC. Nitrite Protects Neurons Against Hypoxic Damage Through S-nitrosylation of Caspase-6. Antioxid Redox Signal 2019; 31:109-126. [PMID: 30417658 DOI: 10.1089/ars.2018.7522] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Aims: The coordination of neurons to execute brain functions requires plenty of oxygen. Thus, it is not surprising that the chronic hypoxia resulting from chronic obstructive pulmonary diseases (COPD) can cause neuronal damage. Injury in the cortex can give rise to anxiety and cognitive dysfunction. This study investigated what causes hypoxia-induced neuronal injury and what strategies might be used to protect neurons against such damage. Results: This study found that hypoxia in primary cortical neurons caused neurite retraction, a caspase-6-dependent process. The hypoxic stress activated caspase-6 within the neurite, leading to microtubule disassembly and neurite retraction. The effect of hypoxia on caspase-6 activation, microtubule disassembly, and neurite retraction was alleviated by nitrite treatment. The protective role of nitrite was further supported by the observation that the active-site Cys146 of caspase-6 was S-nitrosylated in hypoxic neuro-2a cells treated with nitrite. We further validated the beneficial effect of nitrite on neuronal function against hypoxic stress in vivo. Using the wild-type or Apo E-/- mice exposed to chronic hypoxia as a model, we demonstrated that supplementing drinking water with nitrite suppressed active caspase-6 in the cortex of the brain, concomitant with the prevention of hypoxia-induced anxiety in the animals. Innovation: These results are the first evidence of a new pathway for the activation of caspase-6 and the first to indicate that nitrite can protect neurons against chronic hypoxic insult. Conclusion: Our findings suggest that nitrite holds great potential for the treatment of diseases such as COPD associated with hypoxia-induced neuronal injury.
Collapse
Affiliation(s)
- Yen-Jung Chen
- 1 Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.,2 Institutes of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yun-Chung Liu
- 1 Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.,2 Institutes of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yu-Wen Liu
- 2 Institutes of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yu-Bin Lee
- 2 Institutes of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hsin-Chieh Huang
- 2 Institutes of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yi-Yun Chen
- 2 Institutes of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | | | - Ying-Chu Lee
- 2 Institutes of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Ching-Feng Cheng
- 4 Department of Medical Research, Tzu Chi University, Hualien, Taiwan.,5 Department of Pediatrics, Tzu Chi General Hospital, Hualien, Taiwan.,6 Institutes of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Tzu-Ching Meng
- 1 Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.,2 Institutes of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| |
Collapse
|
8
|
Yang CF, Chen YY, Singh JP, Hsu SF, Liu YW, Yang CY, Chang CW, Chen SN, Shih RH, Hsu STD, Jou YS, Cheng CF, Meng TC. Targeting protein tyrosine phosphatase PTP-PEST (PTPN12) for therapeutic intervention in acute myocardial infarction. Cardiovasc Res 2019. [DOI: 10.1093/cvr/cvz165] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Abstract
Abstract
Aims
The myocardial ischaemia/reperfusion (I/R) injury is almost inevitable since reperfusion is the only established treatment for acute myocardial infarction (AMI). To date there is no effective strategy available for reducing the I/R injury. Our aim was to elucidate the mechanisms underlying myocardial I/R injury and to develop a new strategy for attenuating the damage it causes.
Methods and results
Using a mouse model established by ligation of left anterior descending artery, we found an increase in activity of protein tyrosine phosphatases (PTPs) in myocardium during I/R. Treating the I/R-mice with a pan-PTP inhibitor phenyl vinyl sulfone attenuated I/R damage, suggesting PTP activation to be harmful in I/R. Through analysing RNAseq data, we showed PTPs being abundantly expressed in mouse myocardium. By exposing primary cardiomyocytes ablated with specific endogenous PTPs by RNAi to hypoxia/reoxygenation (H/R), we found a role that PTP-PEST (PTPN12) plays to promote cell death under H/R stress. Auranofin, a drug being used in clinical practice for treating rheumatoid arthritis, may target PTP-PEST thus suppressing its activity. We elucidated the molecular basis for Auranofin-induced inactivation of PTP-PEST by structural studies, and then examined its effect on myocardial I/R injury. In the mice receiving Auranofin before reperfusion, myocardial PTP activity was suppressed, leading to restored phosphorylation of PTP-PEST substrates, including ErbB-2 that maintains the survival signalling of the heart. In line with the inhibition of PTP-PEST activity, the Auranofin-treated I/R-mice had smaller infarct size and better cardiac function.
Conclusions
PTP-PEST contributes to part of the damages resulting from myocardial I/R. The drug Auranofin, potentially acting through the PTP-PEST-ErbB-2 signalling axis, reduces myocardial I/R injury. Based on this finding, Auranofin could be used in the development of new treatments that manage I/R injury in patients with AMI.
Collapse
Affiliation(s)
- Chiu-Fen Yang
- Department of Cardiology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, 707 Chung-Yang Road Sec. 3, Hualien 970, Taiwan
- Doctoral Degree Program in Translational Medicine, Tzu Chi University and Academia Sinica
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Yi-Yun Chen
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Jai Prakash Singh
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
- Chemical Biology and Molecular Biophysics, Taiwan International Graduate program, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
- Institute of Chemistry, National Tsing-Hua University, 101 Kuang-Fu Road Sec. 2, Hsinchu 300, Taiwan
| | - Shu-Fang Hsu
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Yu-Wen Liu
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Chun-Yi Yang
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, 1 Roosevelt Road Sec. 4, Taipei 106, Taiwan
| | - Chia-Wei Chang
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Szu-Ni Chen
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Rou-Ho Shih
- Institute of Biomedical Sciences, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
- Chemical Biology and Molecular Biophysics, Taiwan International Graduate program, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, 1 Roosevelt Road Sec. 4, Taipei 106, Taiwan
| | - Yuh-Shan Jou
- Institute of Biomedical Sciences, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
| | - Ching-Feng Cheng
- Doctoral Degree Program in Translational Medicine, Tzu Chi University and Academia Sinica
- Institute of Biomedical Sciences, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
- Department of Pediatrics, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, 289 Jianguo Road, Xindian Dist., New Taipei City 231, Taiwan
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
- Chemical Biology and Molecular Biophysics, Taiwan International Graduate program, Academia Sinica, 128 Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, 1 Roosevelt Road Sec. 4, Taipei 106, Taiwan
| |
Collapse
|
9
|
Bottini A, Wu DJ, Ai R, Le Roux M, Bartok B, Bombardieri M, Doody KM, Zhang V, Sacchetti C, Zoccheddu M, Lonic A, Li X, Boyle DL, Hammaker D, Meng TC, Liu L, Corr M, Stanford SM, Lewis M, Wang W, Firestein GS, Khew-Goodall Y, Pitzalis C, Bottini N. PTPN14 phosphatase and YAP promote TGFβ signalling in rheumatoid synoviocytes. Ann Rheum Dis 2019; 78:600-609. [PMID: 30808624 DOI: 10.1136/annrheumdis-2018-213799] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 01/28/2019] [Accepted: 01/30/2019] [Indexed: 11/04/2022]
Abstract
OBJECTIVE We aimed to understand the role of the tyrosine phosphatase PTPN14-which in cancer cells modulates the Hippo pathway by retaining YAP in the cytosol-in fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA). METHODS Gene/protein expression levels were measured by quantitative PCR and/or Western blotting. Gene knockdown in RA FLS was achieved using antisense oligonucleotides. The interaction between PTPN14 and YAP was assessed by immunoprecipitation. The cellular localisation of YAP and SMAD3 was examined via immunofluorescence. SMAD reporter studies were carried out in HEK293T cells. The RA FLS/cartilage coimplantation and passive K/BxN models were used to examine the role of YAP in arthritis. RESULTS RA FLS displayed overexpression of PTPN14 when compared with FLS from patients with osteoarthritis (OA). PTPN14 knockdown in RA FLS impaired TGFβ-dependent expression of MMP13 and potentiation of TNF signalling. In RA FLS, PTPN14 formed a complex with YAP. Expression of PTPN14 or nuclear YAP-but not of a non-YAP-interacting PTPN14 mutant-enhanced SMAD reporter activity. YAP promoted TGFβ-dependent SMAD3 nuclear localisation in RA FLS. Differences in epigenetic marks within Hippo pathway genes, including YAP, were found between RA FLS and OA FLS. Inhibition of YAP reduced RA FLS pathogenic behaviour and ameliorated arthritis severity. CONCLUSION In RA FLS, PTPN14 and YAP promote nuclear localisation of SMAD3. YAP enhances a range of RA FLS pathogenic behaviours which, together with epigenetic evidence, points to the Hippo pathway as an important regulator of RA FLS behaviour.
Collapse
Affiliation(s)
- Angel Bottini
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA.,Division of Cellular Biology, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Dennis J Wu
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA
| | - Rizi Ai
- Dept. of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Michelle Le Roux
- Division of Cellular Biology, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Beatrix Bartok
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA
| | - Michele Bombardieri
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Karen M Doody
- Division of Cellular Biology, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Vida Zhang
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA.,Division of Cellular Biology, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Cristiano Sacchetti
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA.,Division of Cellular Biology, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Martina Zoccheddu
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA
| | - Ana Lonic
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, South Australia, Australia
| | - Xiaochun Li
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, South Australia, Australia
| | - David L Boyle
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA
| | - Deepa Hammaker
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA
| | - Tzu-Ching Meng
- Institute for Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Lin Liu
- Dept. of Family Medicine and Public Health, University of California San Diego, La Jolla, CA, USA
| | - Maripat Corr
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA
| | - Stephanie M Stanford
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA.,Division of Cellular Biology, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Myles Lewis
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Wei Wang
- Dept. of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA.,Dept. of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | - Gary S Firestein
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA
| | - Yeesim Khew-Goodall
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, South Australia, Australia
| | - Costantino Pitzalis
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Nunzio Bottini
- Dept. of Medicine, University of California San Diego, La Jolla, California, USA .,Division of Cellular Biology, La Jolla Institute for Immunology, La Jolla, CA, USA
| |
Collapse
|
10
|
Hsu SF, Lee YB, Lee YC, Chung AL, Apaya MK, Shyur LF, Cheng CF, Ho FM, Meng TC. Dual specificity phosphatase DUSP6 promotes endothelial inflammation through inducible expression of ICAM-1. FEBS J 2018; 285:1593-1610. [PMID: 29493888 DOI: 10.1111/febs.14425] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 02/12/2018] [Accepted: 02/23/2018] [Indexed: 12/30/2022]
Abstract
Tumor necrosis factor (TNF)-α activates a diverse array of signaling pathways in vascular endothelial cells (ECs), leading to the inflammatory phenotype that contributes to the vascular dysfunction and neutrophil emigration in patients with sepsis. To date, it is not well understood what key regulator might coordinate signaling pathways to achieve inflammatory response in TNF-α-stimulated ECs. This study investigated the role of dual specificity phosphatase-6 (DUSP6) in the regulation of endothelial inflammation. Using knockout mice, we found that DUSP6 is important for TNF-α-induced endothelial intercellular adhesion molecule-1 (ICAM-1) expression in aorta and in vein. Moreover, genetic deletion of Dusp6 in pulmonary circulation significantly alleviated the susceptibility of mice to lung injury caused by neutrophil recruitment during experimental sepsis induced by TNF-α or lipopolysaccharide (LPS). The role of DUSP6 was further investigated in primary human umbilical vein endothelial cells (HUVECs). Employing RNAi approach in which endogenous DUSP6 was ablated, we showed a critical function of DUSP6 to facilitate TNF-α-induced ICAM-1 expression and endothelial leukocyte interaction. Interestingly, DUSP6-promoted endothelial inflammation is independent of extracellular signaling-regulated kinase (ERK) signaling. On the other hand, inducible DUSP6 leads to activation of canonical nuclear factor (NF)-κB-mediated transcription of ICAM-1 gene in TNF-α-stimulated human ECs. These results are the first to demonstrate a positive role of DUSP6 in endothelial inflammation-mediated pathological process and the underlying mechanism through which DUSP6 promotes NF-κB signaling in the inflamed ECs. Our findings suggest that manipulation of DUSP6 holds great potential for the treatment of acute inflammatory diseases.
Collapse
Affiliation(s)
- Shu-Fang Hsu
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.,Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yu-Bin Lee
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Ying-Chu Lee
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Ai-Ling Chung
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | | | - Lie-Fen Shyur
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Ching-Feng Cheng
- Department of Medical Research, Tzu Chi University, Hualien, Taiwan.,Department of Pediatrics, Tzu Chi General Hospital, Hualien, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Feng-Ming Ho
- Department of Internal Medicine, Taipei Medical University, Taiwan.,Division of Cardiology, Department of Internal Medicine, Taoyuan General Hospital, Ministry of Health and Welfare, Taoyuan, Taiwan.,R&D Center for Membrane Technology, Department of Chemical Engineering, Chung Yuan Christian University, Taoyuan, Taiwan
| | - Tzu-Ching Meng
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.,Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| |
Collapse
|
11
|
Willoughby LF, Manent J, Allan K, Lee H, Portela M, Wiede F, Warr C, Meng TC, Tiganis T, Richardson HE. Differential regulation of protein tyrosine kinase signalling by Dock and the PTP61F variants. FEBS J 2017; 284:2231-2250. [PMID: 28544778 DOI: 10.1111/febs.14118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 04/12/2017] [Accepted: 05/19/2017] [Indexed: 01/01/2023]
Abstract
Tyrosine phosphorylation-dependent signalling is coordinated by the opposing actions of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). There is a growing list of adaptor proteins that interact with PTPs and facilitate the dephosphorylation of substrates. The extent to which any given adaptor confers selectivity for any given substrate in vivo remains unclear. Here we have taken advantage of Drosophila melanogaster as a model organism to explore the influence of the SH3/SH2 adaptor protein Dock on the abilities of the membrane (PTP61Fm)- and nuclear (PTP61Fn)-targeted variants of PTP61F (the Drosophila othologue of the mammalian enzymes PTP1B and TCPTP respectively) to repress PTK signalling pathways in vivo. PTP61Fn effectively repressed the eye overgrowth associated with activation of the epidermal growth factor receptor (EGFR), PTK, or the expression of the platelet-derived growth factor/vascular endothelial growth factor receptor (PVR) or insulin receptor (InR) PTKs. PTP61Fn repressed EGFR and PVR-induced mitogen-activated protein kinase signalling and attenuated PVR-induced STAT92E signalling. By contrast, PTP61Fm effectively repressed EGFR- and PVR-, but not InR-induced tissue overgrowth. Importantly, coexpression of Dock with PTP61F allowed for the efficient repression of the InR-induced eye overgrowth, but did not enhance the PTP61Fm-mediated inhibition of EGFR and PVR-induced signalling. Instead, Dock expression increased, and PTP61Fm coexpression further exacerbated the PVR-induced eye overgrowth. These results demonstrate that Dock selectively enhances the PTP61Fm-mediated attenuation of InR signalling and underscores the specificity of PTPs and the importance of adaptor proteins in regulating PTP function in vivo.
Collapse
Affiliation(s)
| | - Jan Manent
- Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Kirsten Allan
- Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Han Lee
- Institute of Biochemical Sciences, National Taiwan University, and Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Marta Portela
- Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Florian Wiede
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Department of Biochemistry & Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Coral Warr
- School of Biomedical Sciences, Monash University, Clayton, Victoria, Australia
| | - Tzu-Ching Meng
- Institute of Biochemical Sciences, National Taiwan University, and Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Tony Tiganis
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Department of Biochemistry & Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Helena E Richardson
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.,Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia.,Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia.,Department of Biochemistry & Molecular Biology, University of Melbourne, Victoria, Australia.,Department of Anatomy & Neuroscience, University of Melbourne, Victoria, Australia
| |
Collapse
|
12
|
Huang YJ, Yang CK, Wei PL, Huynh TT, Whang-Peng J, Meng TC, Hsiao M, Tzeng YM, Wu AT, Yen Y. Ovatodiolide suppresses colon tumorigenesis and prevents polarization of M2 tumor-associated macrophages through YAP oncogenic pathways. J Hematol Oncol 2017; 10:60. [PMID: 28241877 PMCID: PMC5329923 DOI: 10.1186/s13045-017-0421-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 02/14/2017] [Indexed: 02/06/2023] Open
Abstract
Background An increased expression of Yes-associated protein (YAP1) has been shown to promote tumorigenesis in many cancer types including colon. However, the role of YAP1 in promoting colon tumorigenesis remains unclear. Here, we demonstrate that YAP1 expression is associated with M2 tumor-associated macrophage polarization and the generation of colon cancer stem-like cells. YAP1 downregulation by gene silencing or a phytochemical, ovatodiolide, not only suppresses colon cancer tumorigenesis but also prevents M2 TAM polarization. Methods Human monocytic cells, THP-1, and colon cancer cell lines, HCT116 and DLD-1, were co-cultured to mimic the interactions between tumor and its microenvironment. M2 polarization of the THP-1 cells were examined using both flow cytometry and q-PCR technique. The inhibition of YAP1 signaling was achieved by gene-silencing technique or ovatodiolide. The molecular consequences of YAP1 inhibition was demonstrated via colony formation, migration, and colon-sphere formation assays. 5-FU and ovatodiolide were used in drug combination studies. Xenograft and syngeneic mouse models were used to investigate the role of YAP1 in colon tumorigenesis and TAM generation. Results An increased YAP1 expression was found to be associated with a poor prognosis in patients with colon cancer using bioinformatics approach. We showed an increased YAP1 expression in the colon spheres, and colon cancer cells co-cultured with M2 TAMs. YAP1-silencing led to the concomitant decreased expression of major oncogenic pathways including Kras, mTOR, β-catenin, and M2-promoting IL-4 and tumor-promoting IL-6 cytokines. TAM co-cultured colon spheres showed a significantly higher tumor-initiating ability in vivo. Ovatodiolide treatment alone and in combination with 5-FU significantly suppressed in vivo tumorigenesis and less TAM infiltration in CT26 syngeneic mouse model. Conclusions We have identified the dual function of YAP1 where its suppression not only inhibited tumorigenesis but also prevented the generation of cancer stem-like cells and M2 TAM polarization. Ovatodiolide treatment suppressed YAP1 oncogenic pathways to inhibit colon tumorigenesis and M2 TAM generation both in vitro and in vivo. Ovatodiolide should be considered for its potential for adjuvant therapeutic development. Electronic supplementary material The online version of this article (doi:10.1186/s13045-017-0421-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Yan-Jiun Huang
- The PhD Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.,Division of Colorectal Surgery, Department of Surgery, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan.,Department of Surgery, College of Medicine, Taipei Medical University, Taipei, Taiwan, People's Republic of China
| | - Ching-Kuo Yang
- Division of Colorectal Surgery, Department of Surgery, Mackay Memorial Hospital, Taipei, Taiwan
| | - Po-Li Wei
- Division of Colorectal Surgery, Department of Surgery, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan.,Department of Surgery, College of Medicine, Taipei Medical University, Taipei, Taiwan, People's Republic of China
| | - Thanh-Tuan Huynh
- Center for Molecular Biomedicine, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam
| | - Jacqueline Whang-Peng
- Division of Cancer Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.,Center of Excellence for Cancer Research, Taipei Medical University, Taipei, Taiwan
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Michael Hsiao
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Yew-Ming Tzeng
- Center for General Education, National Taitung University, Taitung, 95092, Taiwan.,Department of Life Science, National Taitung University, Taitung, Taiwan
| | - Alexander Th Wu
- The PhD Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Yun Yen
- The PhD Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan. .,The PhD Program of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.
| |
Collapse
|
13
|
Hsu MF, Pan KT, Chang FY, Khoo KH, Urlaub H, Cheng CF, Chang GD, Haj FG, Meng TC. S-nitrosylation of endogenous protein tyrosine phosphatases in endothelial insulin signaling. Free Radic Biol Med 2016; 99:199-213. [PMID: 27521458 PMCID: PMC5514559 DOI: 10.1016/j.freeradbiomed.2016.08.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 08/03/2016] [Accepted: 08/09/2016] [Indexed: 01/08/2023]
Abstract
Nitric oxide (NO) exerts its biological function through S-nitrosylation of cellular proteins. Due to the labile nature of this modification under physiological condition, identification of S-nitrosylated residue in enzymes involved in signaling regulation remains technically challenging. The present study investigated whether intrinsic NO produced in endothelium-derived MS-1 cells response to insulin stimulation might target endogenous protein tyrosine phosphatases (PTPs). For this, we have developed an approach using a synthetic reagent that introduces a phenylacetamidyl moiety on S-nitrosylated Cys, followed by detection with anti-phenylacetamidyl Cys (PAC) antibody. Coupling with sequential blocking of free thiols with multiple iodoacetyl-based Cys-reactive chemicals, we employed this PAC-switch method to show that endogenous SHP-2 and PTP1B were S-nitrosylated in MS-1 cells exposed to insulin. The mass spectrometry detected a phenylacetamidyl moiety specifically present on the active-site Cys463 of SHP-2. Focusing on the regulatory role of PTP1B, we showed S-nitrosylation to be the principal Cys reversible redox modification in endothelial insulin signaling. The PAC-switch method in an imaging format illustrated that a pool of S-nitrosylated PTP1B was colocalized with activated insulin receptor to the cell periphery, and that such event was endothelial NO synthase (eNOS)-dependent. Moreover, ectopic expression of the C215S mutant of PTP1B that mimics the active-site Cys215 S-nitrosylated form restored insulin responsiveness in eNOS-ablated cells, which was otherwise insensitive to insulin stimulation. This work not only introduces a new method that explores the role of physiological NO in regulating signal transduction, but also highlights a positive NO effect on promoting insulin responsiveness through S-nitrosylation of PTP1B's active-site Cys215.
Collapse
Affiliation(s)
- Ming-Fo Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Kuan-Ting Pan
- Bioanalytical Mass Spectrometry Group, Max Plank Institute for Biophysical Chemistry, Göttingen, Germany
| | - Fan-Yu Chang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, College of Life Sciences, National Taiwan University, Taipei, Taiwan
| | - Kay-Hooi Khoo
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, College of Life Sciences, National Taiwan University, Taipei, Taiwan
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Plank Institute for Biophysical Chemistry, Göttingen, Germany; Bioanalytics Research Group, Department of Clinical Chemistry, University Medical Center, Göttingen, Germany
| | - Ching-Feng Cheng
- Department of Medical Research, Tzu Chi University and Department of Pediatrics, Tzu Chi General Hospital, Hualien, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Geen-Dong Chang
- Institute of Biochemical Sciences, College of Life Sciences, National Taiwan University, Taipei, Taiwan.
| | - Fawaz G Haj
- Department of Nutrition, University of California Davis, Davis, CA, USA.
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, College of Life Sciences, National Taiwan University, Taipei, Taiwan.
| |
Collapse
|
14
|
Wang AH, Chen KE, Lin SY, Ho MR, Chou CC, Meng TC. An integrative approach targeting phosphatase-substrate complexes for new cancer drug design strategy. Acta Crystallogr A Found Adv 2015. [DOI: 10.1107/s2053273315099581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
15
|
Chen KE, Li MY, Chou CC, Ho MR, Chen GC, Meng TC, Wang AJ. Substrate Specificity and Plasticity of FERM-Containing Protein Tyrosine Phosphatases. Structure 2015; 23:653-64. [DOI: 10.1016/j.str.2015.01.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Revised: 01/18/2015] [Accepted: 01/24/2015] [Indexed: 10/23/2022]
|
16
|
Hatzihristidis T, Desai N, Hutchins AP, Meng TC, Tremblay ML, Miranda-Saavedra D. A Drosophila-centric view of protein tyrosine phosphatases. FEBS Lett 2015; 589:951-66. [PMID: 25771859 DOI: 10.1016/j.febslet.2015.03.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/02/2015] [Accepted: 03/02/2015] [Indexed: 12/30/2022]
Abstract
Most of our knowledge on protein tyrosine phosphatases (PTPs) is derived from human pathologies and mouse knockout models. These models largely correlate well with human disease phenotypes, but can be ambiguous due to compensatory mechanisms introduced by paralogous genes. Here we present the analysis of the PTP complement of the fruit fly and the complementary view that PTP studies in Drosophila will accelerate our understanding of PTPs in physiological and pathological conditions. With only 44 PTP genes, Drosophila represents a streamlined version of the human complement. Our integrated analysis places the Drosophila PTPs into evolutionary and functional contexts, thereby providing a platform for the exploitation of the fly for PTP research and the transfer of knowledge onto other model systems.
Collapse
Affiliation(s)
- Teri Hatzihristidis
- Goodman Cancer Research Centre, McGill University, 1160 Pine Avenue, Montreal, Québec H3A 1A3, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada
| | - Nikita Desai
- Goodman Cancer Research Centre, McGill University, 1160 Pine Avenue, Montreal, Québec H3A 1A3, Canada; Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Andrew P Hutchins
- Key Laboratory of Regenerative Biology and Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong 510530, China
| | - Tzu-Ching Meng
- Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan; Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Michel L Tremblay
- Goodman Cancer Research Centre, McGill University, 1160 Pine Avenue, Montreal, Québec H3A 1A3, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, Quebec, Canada; Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
| | - Diego Miranda-Saavedra
- World Premier International (WPI) Immunology Frontier Research Center (IFReC), Osaka University, 3-1 Yamadaoka, Suita 565-0871, Osaka, Japan; Centro de Biología Molecular Severo Ochoa, CSIC/Universidad Autónoma de Madrid, 28049 Madrid, Spain; IE Business School, IE University, María de Molina 31 bis, 28006 Madrid, Spain.
| |
Collapse
|
17
|
Meng TC, Chen YJ. Therapeutic potential of nitrite in obstructive sleep apnea: Targeting caspase-6 by nitrite-generated no for intervention in hypoxia-induced neuronal injury. Nitric Oxide 2014. [DOI: 10.1016/j.niox.2014.09.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
18
|
Chen KE, Lin SY, Wu MJ, Ho MR, Santhanam A, Chou CC, Meng TC, Wang AHJ. Reciprocal allosteric regulation of p38γ and PTPN3 involves a PDZ domain-modulated complex formation. Sci Signal 2014; 7:ra98. [PMID: 25314968 DOI: 10.1126/scisignal.2005722] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The mitogen-activated protein kinase p38γ (also known as MAPK12) and its specific phosphatase PTPN3 (also known as PTPH1) cooperate to promote Ras-induced oncogenesis. We determined the architecture of the PTPN3-p38γ complex by a hybrid method combining x-ray crystallography, small-angle x-ray scattering, and chemical cross-linking coupled to mass spectrometry. A unique feature of the glutamic acid-containing loop (E-loop) of the phosphatase domain defined the substrate specificity of PTPN3 toward fully activated p38γ. The solution structure revealed the formation of an active-state complex between p38γ and the phosphatase domain of PTPN3. The PDZ domain of PTPN3 stabilized the active-state complex through an interaction with the PDZ-binding motif of p38γ. This interaction alleviated autoinhibition of PTPN3, enabling efficient tyrosine dephosphorylation of p38γ. Our findings may enable structure-based drug design targeting the PTPN3-p38γ interaction as an anticancer therapeutic.
Collapse
Affiliation(s)
- Kai-En Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan
| | - Shu-Yu Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan
| | - Mei-Ju Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan
| | - Meng-Ru Ho
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan
| | - Abirami Santhanam
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan
| | - Chia-Cheng Chou
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan. National Core Facility for Protein Structural Analysis, Academia Sinica, Taipei 11581, Taiwan
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan. Institute of Biochemical Sciences, National Taiwan University, Taipei 10717, Taiwan.
| | - Andrew H J Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan. National Core Facility for Protein Structural Analysis, Academia Sinica, Taipei 11581, Taiwan. Institute of Biochemical Sciences, National Taiwan University, Taipei 10717, Taiwan. Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 11047, Taiwan.
| |
Collapse
|
19
|
Abstract
The kinase p38γ and the phosphatase PTPN3 allosterically regulate one another's activity.
Collapse
Affiliation(s)
- Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10717, Taiwan
| | - Kai-En Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan
| | - Andrew H. -J. Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11581, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10717, Taiwan
| | - Annalisa M. VanHook
- Web Editor, Science Signaling, American Association for the Advancement of Science, 1200 New York Avenue, NW, Washington, DC 20005, USA
| |
Collapse
|
20
|
Tchankouo-Nguetcheu S, Udinotti M, Durand M, Meng TC, Taouis M, Rabinow L. Negative regulation of MAP kinase signaling in Drosophila by Ptp61F/PTP1B. Mol Genet Genomics 2014; 289:795-806. [DOI: 10.1007/s00438-014-0852-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 04/01/2014] [Indexed: 01/19/2023]
|
21
|
Pan KT, Chen YY, Pu TH, Chao YS, Yang CY, Bomgarden RD, Rogers JC, Meng TC, Khoo KH. Mass spectrometry-based quantitative proteomics for dissecting multiplexed redox cysteine modifications in nitric oxide-protected cardiomyocyte under hypoxia. Antioxid Redox Signal 2014; 20:1365-81. [PMID: 24152285 PMCID: PMC3936484 DOI: 10.1089/ars.2013.5326] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Revised: 08/22/2013] [Accepted: 09/07/2013] [Indexed: 11/13/2022]
Abstract
AIMS Distinctive states of redox-dependent cysteine (Cys) modifications are known to regulate signaling homeostasis under various pathophysiological conditions, including myocardial injury or protection in response to ischemic stress. Recent evidence further implicates a dynamic interplay among these modified forms following changes in cellular redox environment. However, a precise delineation of multiplexed Cys modifications in a cellular context remains technically challenging. To this end, we have now developed a mass spectrometry (MS)-based quantitative approach using a set of novel iodoacetyl-based Cys-reactive isobaric tags (irreversible isobaric iodoacetyl Cys-reactive tandem mass tag [iodoTMT]) endowed with unique irreversible Cys-reactivities. RESULTS We have established a sequential iodoTMT-switch procedure coupled with efficient immunoenrichment and advanced shotgun liquid chromatography-MS/MS analysis. This workflow allows us to differentially quantify the multiple redox-modified forms of a Cys site in the original cellular context. In one single analysis, we have identified over 260 Cys sites showing quantitative differences in multiplexed redox modifications from the total lysates of H9c2 cardiomyocytes experiencing hypoxia in the absence and presence of S-nitrosoglutathione (GSNO), indicative of a distinct pattern of individual susceptibility to S-nitrosylation or S-glutathionylation. Among those most significantly affected are proteins functionally implicated in hypoxic damage from which we showed that GSNO would protect. INNOVATION We demonstrate for the first time how quantitative analysis of various Cys-redox modifications occurring in biological samples can be performed precisely and simultaneously at proteomic levels. CONCLUSION We have not only developed a new approach to map global Cys-redoxomic regulation in vivo, but also provided new evidences implicating Cys-redox modifications of key molecules in NO-mediated ischemic cardioprotection.
Collapse
Affiliation(s)
- Kuan-Ting Pan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Yi-Yun Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Tsung-Hsien Pu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei, Taiwan
| | - Yu-Shu Chao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chun-Yi Yang
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | | | | | - Tzu-Ching Meng
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Kay-Hooi Khoo
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| |
Collapse
|
22
|
Chang YC, Tang HW, Liang SY, Pu TH, Meng TC, Khoo KH, Chen GC. Evaluation of Drosophila Metabolic Labeling Strategies for in Vivo Quantitative Proteomic Analyses with Applications to Early Pupa Formation and Amino Acid Starvation. J Proteome Res 2013; 12:2138-50. [DOI: 10.1021/pr301168x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Ying-Che Chang
- Institute
of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical
Sciences, National Taiwan University, Taipei,
Taiwan
- Clinical Proteomics
Center, Chang Gung Memorial Hospital, Taoyuan,
Taiwan
| | - Hong-Wen Tang
- Institute
of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical
Sciences, National Taiwan University, Taipei,
Taiwan
| | - Suh-Yuen Liang
- NRPB
Core Facilities for Protein
Structural Analysis, Academia Sinica, Taipei,
Taiwan
| | - Tsung-Hsien Pu
- NRPB
Core Facilities for Protein
Structural Analysis, Academia Sinica, Taipei,
Taiwan
| | - Tzu-Ching Meng
- Institute
of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical
Sciences, National Taiwan University, Taipei,
Taiwan
| | - Kay-Hooi Khoo
- Institute
of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical
Sciences, National Taiwan University, Taipei,
Taiwan
| | - Guang-Chao Chen
- Institute
of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical
Sciences, National Taiwan University, Taipei,
Taiwan
| |
Collapse
|
23
|
|
24
|
Santhanam A, Liang SY, Chen DY, Chen GC, Meng TC. Midgut-enriched receptor protein tyrosine phosphatase PTP52F is required forDrosophiladevelopment during larva-pupa transition. FEBS J 2012; 280:476-88. [DOI: 10.1111/j.1742-4658.2012.08696.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
25
|
Chen DY, Li MY, Wu SY, Lin YL, Tsai SP, Lai PL, Lin YT, Kuo JC, Meng TC, Chen GC. The Bro1 domain-containing Myopic/HDPTP coordinates with Rab4 to regulate cell adhesion and migration. J Cell Sci 2012; 125:4841-52. [DOI: 10.1242/jcs.108597] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Protein tyrosine phosphatases (PTPs) are a group of tightly regulated enzymes that coordinate with protein tyrosine kinases to control protein phosphorylation during various cellular processes. Using genetic analysis in Drosophila non-transmembrane PTPs, we identified one role that Myopic (Mop), the Drosophila homolog of the human His domain phosphotyrosine phosphatase (HDPTP), plays in cell adhesion. Depletion of Mop results in aberrant integrin distribution and border cell dissociation during Drosophila oogenesis. Interestingly, Mop phosphatase activity is not required for its role in maintaining border cell cluster integrity. We further identified Rab4 GTPase as a Mop interactor in a yeast two-hybrid screen. Expression of the Rab4 dominant negative mutant leads to border cell dissociation and suppresses Mop-induced wing-blade adhesion defects, suggesting a critical role of Rab4 in Mop-mediated signaling. In mammals, it has been shown that Rab4-dependent recycling of integrins is necessary for cell adhesion and migration. We found that human HDPTP regulates the spatial distribution of Rab4 and integrin trafficking. Depletion of HDPTP resulted in actin reorganization and increased cell motility. Together, our findings suggest an evolutionarily conserved function of HDPTP-Rab4 in the regulation of endocytic trafficking, cell adhesion and migration.
Collapse
|
26
|
Lai YC, Pan KT, Chang GF, Hsu CH, Khoo KH, Hung CH, Jiang YJ, Ho FM, Meng TC. Nitrite-mediated S-nitrosylation of caspase-3 prevents hypoxia-induced endothelial barrier dysfunction. Circ Res 2011; 109:1375-86. [PMID: 22021929 DOI: 10.1161/circresaha.111.256479] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
RATIONALE Hypoxia is a significant perturbation that exacerbates endothelial barrier dysfunction, contributing to the disruption of vascular homeostasis and the development of various diseases such as atherosclerosis and metastasis of tumors. To date, it is not known what strategy might be used to counter the effect of hypoxia on endothelial permeability. OBJECTIVE This study investigated the role of nitrite in regulating vascular integrity under hypoxic conditions. METHODS AND RESULTS We found denitrosylation and the resulting activation of caspase-3 to be critical for hypoxia-induced endothelial permeability. Nitrite treatment led to S-nitrosylation and the inactivation of caspase-3, suppressing the barrier dysfunction of endothelia caused by hypoxia. This process required the conversion of nitrite to bioactive nitric oxide in a nitrite reductase-dependent manner. Using primary human umbilical vein endothelial cells as a model, we showed that in the presence of nitrite, the S-nitrosylated and inactivated form of caspase-3 was unable to cleave β-catenin, a key component in the VE-cadherin complex. Therefore, nitrite treatment led to the maintenance of VE-cadherin-mediated adherens junctions under hypoxic conditions. In in vivo experiments using a zebrafish model, nitrite was found to protect blood vessels from hypoxia-induced vascular leakage. CONCLUSIONS These results are the first to demonstrate that nitrite plays a critical role in the protection of endothelial barrier function against hypoxic insult. Our findings show that nitrite holds great potential for the treatment of diseases associated with hypoxia-induced disorder of vascular homeostasis.
Collapse
Affiliation(s)
- Yen-Chun Lai
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Fishelevich R, Zhao Y, Tuchina P, Liu H, Nakazono A, Tammaro A, Meng TC, Lee J, Gaspari AA. Imiquimod-induced TLR7 signaling enhances repair of DNA damage induced by ultraviolet light in bone marrow-derived cells. J Immunol 2011; 187:1664-73. [PMID: 21765012 PMCID: PMC3150393 DOI: 10.4049/jimmunol.1100755] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Imiquimod is a TLR7/8 agonist that has anticancer therapeutic efficacy in the treatment of precancerous skin lesions and certain nonmelanoma skin cancers. To test our hypothesis that imiquimod enhances DNA repair as a mechanism for its anticancer activity, the nucleotide excision repair genes were studied in bone marrow-derived cells. Imiquimod enhanced the expression of xeroderma pigmentosum (XP) A and other DNA repair genes (quantitative real-time PCR analysis) and resulted in an increased nuclear localization of the DNA repair enzyme XPA. This was dependent on MyD88, as bone marrow-derived cells from MyD88(-/-) mice did not increase XPA gene expression and did not enhance the survival of MyD88(-/-)-derived bone marrow-derived cells after UV B exposure as was observed in bone marrow-derived cells from MyD88(+/+) mice. Imiquimod also enhanced DNA repair of UV light (UVL)-irradiated gene expression constructs and accelerated the resolution of cyclobutane pyrimidine dimers after UVL exposures in P388 and XS52. Lastly, topical treatment of mouse skin with 5% imiquimod cream prior to UVL irradiation resulted in a decrease in the number of cyclobutane pyridimine dimer-positive APC that were found in local lymph nodes 24 h after UVL irradiation in both wild-type and IL-12 gene-targeted mice. In total, these data support the idea that TLR7 agonists such as imiquimod enhance DNA repair in bone marrow-derived cells. This property is likely to be an important mechanism for its anticancer effects because it protects cutaneous APC from the deleterious effects of UVL.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Jim Lee
- Graceway Pharmaceutical Company, Exton, PA
| | - Anthony A. Gaspari
- Department of Dermatology, Exton, PA
- Department of Microbiology/Immunology, University of Maryland Baltimore, School of Medicine, Baltimore, MD
| |
Collapse
|
28
|
Lai YC, Pan KT, Khoo KH, Meng TC. P50. Nitrite-mediated S-nitrosylation of caspase-3 prevents hypoxia-induced endothelial barrier dysfunction. Nitric Oxide 2011. [DOI: 10.1016/j.niox.2011.03.281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
29
|
Abstract
NO synthesis is a prerequisite for proper insulin sensitivity in insulin-targeted tissues; however, the molecular basis for this process remains unclear. Using a gain-of-function model of endothelial nitric-oxide synthase (eNOS)-transfected COS-7 cells, we have shown a critical role of NO in insulin responsiveness, as evidenced by an NO-dependent increase of tyrosine phosphorylation levels of the insulin receptor and its downstream effectors insulin receptor substrate-1 and PKB/AKT. We hypothesized that NO-induced inactivation of endogenous protein-tyrosine phosphatases (PTPs) would enhance insulin receptor-mediated signaling. To test this hypothesis, we devised a new method of the PTP labeling using a cysteine sulfhydryl-reacted probe. Under the acidic conditions employed in this study, the probe recognized the reduced and active forms but not the S-nitrosylated and inactive forms of endogenous PTPs. Our data suggest that phosphatases SHP-1, SHP-2, and PTP1B, but not TC-PTP, are likely S-nitrosylated at the active site cysteine residue concomitantly with a burst of NO production in signaling response to insulin stimulation. These results were further confirmed by phosphatase activity assays. We investigated further the role of NO as a regulator of insulin signaling by RNA interference that ablates endogenous eNOS expression in endothelial MS-1 cells. We have shown that eNOS-dependent NO production is essential for the activation of insulin signaling. Our findings demonstrate that NO mediates enhancement of insulin responsiveness via the inhibition of insulin receptor phosphatases.
Collapse
Affiliation(s)
- Ming-Fo Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | | |
Collapse
|
30
|
Chen YY, Chu HM, Pan KT, Teng CH, Wang DL, Wang AHJ, Khoo KH, Meng TC. Cysteine S-nitrosylation protects protein-tyrosine phosphatase 1B against oxidation-induced permanent inactivation. J Biol Chem 2008; 283:35265-72. [PMID: 18840608 DOI: 10.1074/jbc.m805287200] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein S-nitrosylation mediated by cellular nitric oxide (NO) plays a primary role in executing biological functions in cGMP-independent NO signaling. Although S-nitrosylation appears similar to Cys oxidation induced by reactive oxygen species, the molecular mechanism and biological consequence remain unclear. We investigated the structural process of S-nitrosylation of protein-tyrosine phosphatase 1B (PTP1B). We treated PTP1B with various NO donors, including S-nitrosothiol reagents and compound-releasing NO radicals, to produce site-specific Cys S-nitrosylation identified using advanced mass spectrometry (MS) techniques. Quantitative MS showed that the active site Cys-215 was the primary residue susceptible to S-nitrosylation. The crystal structure of NO donor-reacted PTP1B at 2.6 A resolution revealed that the S-NO state at Cys-215 had no discernible irreversibly oxidized forms, whereas other Cys residues remained in their free thiol states. We further demonstrated that S-nitrosylation of the Cys-215 residue protected PTP1B from subsequent H(2)O(2)-induced irreversible oxidation. Increasing the level of cellular NO by pretreating cells with an NO donor or by activating ectopically expressed NO synthase inhibited reactive oxygen species-induced irreversible oxidation of endogenous PTP1B. These findings suggest that S-nitrosylation might prevent PTPs from permanent inactivation caused by oxidative stress.
Collapse
Affiliation(s)
- Yi-Yun Chen
- Institute of Biological Chemistry, National Core Facility for Proteomics Research, Academia Sinica, Taipei 11529, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Chang YC, Lin SY, Liang SY, Pan KT, Chou CC, Chen CH, Liao CL, Khoo KH, Meng TC. Tyrosine phosphoproteomics and identification of substrates of protein tyrosine phosphatase dPTP61F in Drosophila S2 cells by mass spectrometry-based substrate trapping strategy. J Proteome Res 2008; 7:1055-66. [PMID: 18281928 DOI: 10.1021/pr700801p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent biochemical and genetic approaches have clearly defined the functional role of critical components in tyrosine phosphorylation-dependent signal transduction. These signaling modulators often exhibit evolutionarily conserved functions across various species. It has been proposed that if protein tyrosine kinases (PTKs), protein tyrosine phosphatases (PTPs), and thousands of their substrates could be identified and characterized, it would significantly advance our understanding of the underlying mechanisms that control animal development and physiological homeostasis. The fruit fly Drosophila melanogester has been used extensively as a model organism for investigating the developmental processes, but the state of its tyrosine phosphorylation is poorly characterized. In the current study, we used advanced mass spectrometry (MS)-based shotgun analyses to profile the tyrosine phosphoproteome of Drosophila S2 cells. Using immunoaffinity isolation of the phosphotyrosine (pTyr) subproteome from cells treated with pervanadate followed by enrichment of phosphopeptides, we identified 562 nonredundant pTyr sites in 245 proteins. Both this predefined pTyr proteome subset and the total cell lysates were then used as sample sources to identify potential substrates of dPTP61F, the smallest member in terms of amino acid number and molecular weight in the Drosophila PTP family and the ortholog of human PTP1B and T Cell-PTP, by substrate trapping. In total, 20 unique proteins were found to be specifically associated with the trapping mutant form of dPTP61F, eluted by vanadate (VO4(3-)), and identified by MS analyses. Among them, 16 potential substrates were confirmed as tyrosine phosphorylated proteins, including a receptor PTK PDGF/VEGF receptor, a cytosolic PTK Abl, and several components of SCAR/WAVE complex, which may work in coordination to control actin dynamics. Thus, our data suggest that dPTP61F plays a central role in counteracting PTK-mediated signaling pathways as well as in regulating actin reorganization and remodeling through tyrosine dephosphorylation of critical substrates in Drosophila cells.
Collapse
Affiliation(s)
- Ying-Che Chang
- Institute of Biochemical Sciences, College of Life Sciences, National Taiwan University, Taipei 106, Taiwan
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
The oxidation and inactivation of protein tyrosine phosphatases is one mechanism by which reactive oxygen species influence tyrosine phosphorylation-dependent signaling events and exert their biological functions. In the present study, we determined the redox status of endogenous protein tyrosine phosphatases in HepG2 and A431 human cancer cells, in which reactive oxygen species are produced constitutively. We used mass spectrometry to assess the state of oxidation of the catalytic cysteine residue of endogenous PTP1B and show that this residue underwent both reversible and irreversible oxidation to high stoichiometry in response to intrinsic reactive oxygen species production. In addition, our data show that the oxidation of PTP1B is specific to the active site Cys, with the other Cys residues in the protein remaining in a reduced state. Treatment of these cells with diphenyleniodonium, an inhibitor of NADPH oxidases, decreased reactive oxygen species levels. This resulted in inhibition of protein tyrosine phosphatase oxidation, concomitant with decreased tyrosine phosphorylation of cellular proteins and inhibition of anchorage-independent cell growth. Therefore, our data also suggest that the high level of intrinsic reactive oxygen species may contribute to the transformed phenotype of HepG2 and A431 cells via constitutive inactivation of cellular protein tyrosine phosphatases.
Collapse
Affiliation(s)
- Yi-Wei Lou
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Abstract
Apoptosis is a precisely controlled physiological mechanism that is required for the elimination of cells during embryonic development, in response to stress and infection as well as in the maintenance of homeostasis. Since the outcome of several of these biological processes is regulated by signaling events involving tyrosine phosphorylation, members of the protein tyrosine phosphatase (PTP) gene family are expected to be of primary importance. Here, we summarize the current literature linking the activities of classical PTPs with the regulation of apoptosis. The recent discovery of caspase-cleavage mediated modulation of a member of this family, PTP-PEST, indicates that other PTPs could be modulated in a similar manner. In light of this, we present an analysis of all murine and human PTPs gene for the presence of putative caspase cleavage motifs. Additional studies linking the activity of PTPs to their own regulation during programmed cell death initiation should provide important insight into the understanding of this fundamental physiological phenomenon.
Collapse
Affiliation(s)
- Maxime Hallé
- The McGill Cancer Center and the Department of Biochemistry, McGill University, Montréal, Québec, Canada
| | | | | |
Collapse
|
34
|
Teng CH, Huang WN, Meng TC. Several dual specificity phosphatases coordinate to control the magnitude and duration of JNK activation in signaling response to oxidative stress. J Biol Chem 2007; 282:28395-28407. [PMID: 17681939 DOI: 10.1074/jbc.m705142200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitogen-activated protein kinases (MAPKs) are important mediators that integrate signaling from upstream pathways in response to various environmental cues. In order to control appropriate gene expression through phosphorylation of transcription factors, the activity of MAPKs must be tightly regulated by the actions coordinated between protein kinases and phosphatases. In this study, we explore the underlying mechanism through which the oxidative stress-activated c-Jun N-terminal kinases (JNKs), members of MAPKs, are regulated by dual specificity phosphatases (DUSPs). DUSPs are a group of enzymes that belong to the superfamily of protein-tyrosine phosphatases. They are able to recognize phospho-Ser/Thr and phospho-Tyr residues in substrates. Using quantitative real time PCR, we found that stimulation of human embryonic kidney 293T cells with H(2)O(2) or xanthine/xanthine oxidase led to inducible expression of multiple DUSPs. We used RNA interference to characterize the functional role of these DUSPs and found rapid and transient induction of DUSP1 and DUSP10 to be essential for determining the appropriate magnitude of JNK activation in response to oxidative stress. The transcription factor ATF2, which is phosphorylated and activated by JNK, is a critical mediator for inducible expression of DUSP1 and DUSP10 in this signaling pathway. We further demonstrated that DUSP4 and DUSP16, both showing significant late phase induction, dephosphorylate JNK effectively, causing the down-regulation of the signaling cascade. Thus, this study provides new insights into the role of several DUSPs that coordinate with each other to control the magnitude and duration of JNK activity in response to oxidative stress.
Collapse
Affiliation(s)
- Chun-Hung Teng
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Rd., Section 2, Taipei 11529, Taiwan
| | - Wen-Nin Huang
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Rd., Section 2, Taipei 11529, Taiwan
| | - Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Rd., Section 2, Taipei 11529, Taiwan.
| |
Collapse
|
35
|
Chen YY, Huang YF, Khoo KH, Meng TC. Mass spectrometry-based analyses for identifying and characterizing S-nitrosylation of protein tyrosine phosphatases. Methods 2007; 42:243-9. [PMID: 17532511 DOI: 10.1016/j.ymeth.2007.03.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Accepted: 03/09/2007] [Indexed: 11/25/2022] Open
Abstract
All members in the protein tyrosine phosphatase (PTP) family of enzymes contain an invariant Cys residue which is absolutely indispensable for catalysis. Due to the unique microenvironment surrounding the active center of PTPs, this Cys residue exhibits an unusually low pKa characteristic, thus being highly susceptible to oxidation or S-nitrosylation. While oxidation-dependent regulation of PTP activity has been extensively examined, the molecular details and biological consequences of PTP S-nitrosylation remain unexplored. We hypothesized that the catalytic Cys residue is targeted by proximal nitric oxide (NO) and its derivatives collectively termed reactive nitrogen species (RNS), leading to nitrosothiol formation concomitant with reversible inactivation of PTPs. To test this hypothesis, we have developed novel strategies to examine the redox status of Cys residues of purified PTP1B that was exposed to NO donor S-Nitroso-N-penicillamine (SNAP). A gel-based method in conjunction with mass spectrometry (MS) analysis revealed that the catalytic Cys215 of PTP1B was reversibly modified when PTP1B was briefly treated with SNAP. In order to further identify the exact mode of NO-induced modification, we employed an online LC-ESI-MS/MS analysis incorporating a mass difference-based, data-dependent acquisition function that effectively mapped the S-nitrosylated Cys residues. Our results demonstrated that treating PTP1B with SNAP led to S-nitrosothiol formation of the catalytic Cys215. Interestingly, SNAP-induced modifications were strictly reversible as highly oxidized Cys derivatives (Cys-SO(2)H or Cys-SO(3)H) were not identified by MS analyses. Thus, the methods introduced in this study provide direct evidence to prove the direct link between S-nitrosylation of the catalytic Cys residue and reversible inactivation of PTPs.
Collapse
Affiliation(s)
- Yi-Yun Chen
- National Core Facility for Proteomics Research, Academia Sinica, Taipei, Taiwan
| | | | | | | |
Collapse
|
36
|
Hallé M, Liu YC, Hardy S, Théberge JF, Blanchetot C, Bourdeau A, Meng TC, Tremblay ML. Caspase-3 regulates catalytic activity and scaffolding functions of the protein tyrosine phosphatase PEST, a novel modulator of the apoptotic response. Mol Cell Biol 2006; 27:1172-90. [PMID: 17130234 PMCID: PMC1800677 DOI: 10.1128/mcb.02462-05] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protein tyrosine phosphatase PEST (PTP-PEST) is involved in the regulation of the actin cytoskeleton. Despite the emerging functions attributed to both PTPs and the actin cytoskeleton in apoptosis, the involvement of PTP-PEST in apoptotic cell death remains to be established. Using several cell-based assays, we showed that PTP-PEST participates in the regulation of apoptosis. As apoptosis progressed, a pool of PTP-PEST localized to the edge of retracting lamellipodia. Expression of PTP-PEST also sensitized cells to receptor-mediated apoptosis. Concertedly, specific degradation of PTP-PEST was observed during apoptosis. Pharmacological inhibitors, immunodepletion experiments, and in vitro cleavage assays identified caspase-3 as the primary regulator of PTP-PEST processing during apoptosis. Caspase-3 specifically cleaved PTP-PEST at the (549)DSPD motif and generated fragments, some of which displayed increased catalytic activity. Moreover, caspase-3 regulated PTP-PEST interactions with paxillin, leupaxin, Shc, and PSTPIP. PTP-PEST acted as a scaffolding molecule connecting PSTPIP to additional partners: paxillin, Shc, Csk, and activation of caspase-3 correlated with the modulation of the PTP-PEST adaptor function. In addition, cleavage of PTP-PEST facilitated cellular detachment during apoptosis. Together, our data demonstrate that PTP-PEST actively contributes to the cellular apoptotic response and reveal the importance of caspases as regulators of PTPs in apoptosis.
Collapse
Affiliation(s)
- Maxime Hallé
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang 115, Taipei, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Nelson KK, Subbaram S, Connor KM, Dasgupta J, Ha XF, Meng TC, Tonks NK, Melendez JA. Redox-dependent matrix metalloproteinase-1 expression is regulated by JNK through Ets and AP-1 promoter motifs. J Biol Chem 2006; 281:14100-10. [PMID: 16569638 DOI: 10.1074/jbc.m601820200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Reactive oxygen species have been shown to play an important role in the regulation of distinct signaling cascades, many of which act upon the production of matrix metalloproteinases (MMP). Using a series of redox-engineered cell lines we have previously demonstrated that MMP-1 expression is sensitive to the alterations in the steady state production of H2O2 (Ranganathan, A. C., Nelson, K. K., Rodriguez, A. M., Kim, K. H., Tower, G. B., Rutter, J. L., Brinckerhoff, C. E., Epstein, C. J., Huang, T. T., Jeffrey, J. J., and Melendez, J. A. (2001) J. Biol. Chem. 276, 14264-14270). In the present study, we investigate the molecular mechanisms involved in the H2O2-mediated induction of MMP-1. Mutational analysis of an MMP-1 promoter indicates that both the single nucleotide polymorphism creating an Ets binding site at -1607 and a proximal AP-1 site at -1602 are required for maximal H2O2-dependent transcription. The redox-sensitive MMP-1 protein expression requires activation of both ERK1/2 and JNK pathways. Importantly, JNK signaling is largely responsible for the H2O2 sensitivity of the MMP-1 promoter, whereas ERK1/2 contributes to both its basal and H2O2 dependence. H2O2 control of Ets-1 expression was ERK1/2-dependent whereas that of c-Jun requires both ERK1/2 and JNK signaling. Chromatin immunoprecipitation assays indicate that binding of the histone acetyltransferase, p300, and the transcription factors Ets-1 and c-Jun to the MMP-1 promoter is redox sensitive. The redox sensitivity of MMP-1 expression is also associated with an increase in the abundance of oxidatively inactivated protein-tyrosine phosphatases. Targeted cytosolic or mitochondrial scavenging of H2O2 prevented all of the aforementioned signals. These studies provide substantial insight into the mechanisms underlying the redox-dependent control of MMP-1 and may lead to the development of novel targeted antioxidant-based inhibitory therapies for controlling MMP-1 expression during degenerative disease processes.
Collapse
Affiliation(s)
- Kristin K Nelson
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208, USA
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Chen CH, Cheng TH, Lin H, Shih NL, Chen YL, Chen YS, Cheng CF, Lian WS, Meng TC, Chiu WT, Chen JJ. Reactive Oxygen Species Generation Is Involved in Epidermal Growth Factor Receptor Transactivation through the Transient Oxidization of Src Homology 2-Containing Tyrosine Phosphatase in Endothelin-1 Signaling Pathway in Rat Cardiac Fibroblasts. Mol Pharmacol 2006; 69:1347-55. [PMID: 16391241 DOI: 10.1124/mol.105.017558] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Endothelin-1 (ET-1) is implicated in fibroblast proliferation, which results in cardiac fibrosis. Both reactive oxygen species (ROS) generation and epidermal growth factor receptor (EGFR) transactivation play critical roles in ET-1 signal transduction. In this study, we used rat cardiac fibroblasts treated with ET-1 to investigate the connection between ROS generation and EGFR transactivation. ET-1 treatment was found to stimulate the phosphorylation of EGFR and ROS generation, which were abolished by ETA receptor antagonist N-(N-(N-((hexahydro-1H-azepin-1-yl)carbonyl)-L-leucyl)-D-tryptophyl)-D-tryptophan (BQ485). NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI), ROS scavenger N-acetyl cysteine (NAC), and p47phox small interfering RNA knockdown all inhibited the EGFR transactivation induced by ET-1. In contrast, EGFR inhibitor 4-(3'-chloroanilino)-6,7-dimethoxyquinazoline (AG-1478) cannot inhibit intracellular ROS generation induced by ET-1. Src homology 2-containing tyrosine phosphatase (SHP-2) was shown to be associated with EGFR during ET-1 treatment by EGFR coimmunoprecipitation. ROS have been reported to transiently oxidize the catalytic cysteine of phosphotyrosine phosphatases to inhibit their activity. We examined the effect of ROS on SHP-2 in cardiac fibroblasts using a modified malachite green phosphatase assay. SHP-2 was transiently oxidized during ET-1 treatment, and this transient oxidization could be repressed by DPI or NAC treatment. In SHP-2 knockdown cells, ET-1-induced phosphorylation of EGFR was dramatically elevated and is not influenced by NAC and DPI. However, this elevation was suppressed by GM6001 [a matrix metalloproteinase (MMP) inhibitor] and heparin binding (HB)-epidermal growth factor (EGF) neutralizing antibody. Our data suggest that ET-1-ETA-mediated ROS generation can transiently inhibit SHP-2 activity to facilitate the MMP-dependent and HB-EGF-stimulated EGFR transactivation and mitogenic signal transduction in rat cardiac fibroblasts.
Collapse
Affiliation(s)
- Cheng-Hsien Chen
- Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan, Republic of China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Meng TC, Hsu SF, Tonks NK. Development of a modified in-gel assay to identify protein tyrosine phosphatases that are oxidized and inactivated in vivo. Methods 2005; 35:28-36. [PMID: 15588983 DOI: 10.1016/j.ymeth.2004.07.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2004] [Indexed: 11/27/2022] Open
Abstract
Protein tyrosine phosphatases (PTPs) comprise a superfamily of enzymes that control a diverse array of signal transduction pathways. However, the function and regulation of many of these enzymes remain undefined. Previous studies have shown that the optimal tyrosine phosphorylation response to various exogenous stimuli requires the production of reactive oxygen species (ROS). It has been proposed that ROS might transiently inactivate inhibitory PTPs, thus facilitating tyrosine phosphorylation-dependent signaling. Interestingly, the unique chemistry of the invariant, active site Cys residue located in the signature motif renders it highly susceptible to oxidation, leading to the inactivation of PTPs. We have developed a novel strategy to identify those PTPs that are oxidized and therefore, inactivated in response to extracellular stimuli. Iodoacetic acid (IAA) was used to alkylate selectively the thiolate anion of the active site Cys in the reduced PTPs. In contrast, any PTPs in which the active site Cys had been oxidized in response to the stimulus were resistant to alkylation. Following this key step to differentiate between the two pools of PTPs, the oxidized phosphatases were reduced back to the active state during the process of a standard in-gel PTP activity assay. This novel technique revealed, for the first time, that multiple cellular PTPs were indeed oxidized and inactivated in response to exogenous hydrogen peroxide. We have used this technique extensively to show that the ligand-stimulated production of intracellular hydrogen peroxide reversibly regulates the activity of specific PTPs in vivo. By defining the precise PTP targets of intracellular oxidants, the mechanistic details of signal transduction can be delineated. Due to the potential use of this method in finding the molecular targets of intracellular oxidants in diverse signaling pathways, we describe here the theoretical background and the detailed protocols of the modified in-gel PTP assay.
Collapse
Affiliation(s)
- Tzu-Ching Meng
- Institute of Biological Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, 105 Taipei, Taiwan, ROC.
| | | | | |
Collapse
|
40
|
Meng TC, Buckley DA, Galic S, Tiganis T, Tonks NK. Regulation of insulin signaling through reversible oxidation of the protein-tyrosine phosphatases TC45 and PTP1B. J Biol Chem 2004; 279:37716-25. [PMID: 15192089 DOI: 10.1074/jbc.m404606200] [Citation(s) in RCA: 207] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many studies have illustrated that the production of reactive oxygen species (ROS) is important for optimal tyrosine phosphorylation and signaling in response to diverse stimuli. Protein-tyrosine phosphatases (PTPs), which are important regulators of signal transduction, are exquisitely sensitive to inhibition after generation of ROS, and reversible oxidation is becoming recognized as a general physiological mechanism for regulation of PTP function. Thus, production of ROS facilitates a tyrosine phosphorylation-dependent cellular signaling response by transiently inactivating those PTPs that normally suppress the signal. In this study, we have explored the importance of reversible PTP oxidation in the signaling response to insulin. Using a modified ingel PTP assay, we show that stimulation of cells with insulin resulted in the rapid and transient oxidation and inhibition of two distinct PTPs, which we have identified as PTP1B and TC45, the 45-kDa spliced variant of the T cell protein-tyrosine phosphatase. We investigated further the role of TC45 as a regulator of insulin signaling by combining RNA interference and the use of substrate-trapping mutants. We have shown that TC45 is an inhibitor of insulin signaling, recognizing the beta-subunit of the insulin receptor as a substrate. The data also suggest that this strategy, using ligand-induced oxidation to tag specific PTPs and using interference RNA and substrate-trapping mutants to illustrate their role as regulators of particular signal transduction pathways, may be applied broadly across the PTP family to explore function.
Collapse
Affiliation(s)
- Tzu-Ching Meng
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | | | | | | | | |
Collapse
|
41
|
Affiliation(s)
- Tzu-Ching Meng
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
| | | |
Collapse
|
42
|
Salmeen A, Andersen JN, Myers MP, Meng TC, Hinks JA, Tonks NK, Barford D. Redox regulation of protein tyrosine phosphatase 1B involves a sulphenyl-amide intermediate. Nature 2003; 423:769-73. [PMID: 12802338 DOI: 10.1038/nature01680] [Citation(s) in RCA: 706] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2003] [Accepted: 04/07/2003] [Indexed: 11/09/2022]
Abstract
The second messenger hydrogen peroxide is required for optimal activation of numerous signal transduction pathways, particularly those mediated by protein tyrosine kinases. One mechanism by which hydrogen peroxide regulates cellular processes is the transient inhibition of protein tyrosine phosphatases through the reversible oxidization of their catalytic cysteine, which suppresses protein dephosphorylation. Here we describe a structural analysis of the redox-dependent regulation of protein tyrosine phosphatase 1B (PTP1B), which is reversibly inhibited by oxidation after cells are stimulated with insulin and epidermal growth factor. The sulphenic acid intermediate produced in response to PTP1B oxidation is rapidly converted into a previously unknown sulphenyl-amide species, in which the sulphur atom of the catalytic cysteine is covalently linked to the main chain nitrogen of an adjacent residue. Oxidation of PTP1B to the sulphenyl-amide form is accompanied by large conformational changes in the catalytic site that inhibit substrate binding. We propose that this unusual protein modification both protects the active-site cysteine residue of PTP1B from irreversible oxidation to sulphonic acid and permits redox regulation of the enzyme by promoting its reversible reduction by thiols.
Collapse
Affiliation(s)
- Annette Salmeen
- Section of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK
| | | | | | | | | | | | | |
Collapse
|
43
|
Galic S, Klingler-Hoffmann M, Fodero-Tavoletti MT, Puryer MA, Meng TC, Tonks NK, Tiganis T. Regulation of insulin receptor signaling by the protein tyrosine phosphatase TCPTP. Mol Cell Biol 2003; 23:2096-108. [PMID: 12612081 PMCID: PMC149470 DOI: 10.1128/mcb.23.6.2096-2108.2003] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The human protein tyrosine phosphatase TCPTP exists as two forms: an endoplasmic reticulum-targeted 48-kDa form (TC48) and a nuclear 45-kDa form (TC45). Although targeted to the nucleus, TC45 can exit in response to specific stimuli to dephosphorylate cytoplasmic substrates. In this study, we investigated the downregulation of insulin receptor (IR) signaling by TCPTP. In response to insulin stimulation, the TC48-D182A and TC45-D182A "substrate-trapping" mutants formed stable complexes with the endogenous tyrosine-phosphorylated IR beta-subunit in 293 cells. Moreover, in response to insulin stimulation, the TC45-D182A mutant accumulated in the cytoplasm of cells overexpressing the IR and in part colocalized with the IR beta-subunit at the cell periphery. These results indicate that the IR may serve as a cellular substrate for both TC48 and TC45. In immortalized TCPTP(-/-) murine embryo fibroblasts, insulin-induced IR beta-subunit tyrosine phosphorylation and protein kinase PKB/Akt activation were enhanced relative to the values in TCPTP(+/+) cells. Importantly, the expression of TC45 or TC48 to physiological levels suppressed the enhanced insulin-induced signaling in TCPTP(-/-) cells. These results indicate that the differentially localized variants of TCPTP may dephosphorylate the IR and downregulate insulin-induced signaling in vivo.
Collapse
MESH Headings
- Animals
- CHO Cells/drug effects
- CHO Cells/enzymology
- Cattle
- Cell Line, Transformed/drug effects
- Cell Line, Transformed/enzymology
- Cell Nucleus/enzymology
- Cells, Cultured/drug effects
- Cells, Cultured/enzymology
- Cricetinae
- Cricetulus
- Cytoplasm/enzymology
- Endoplasmic Reticulum/enzymology
- Enzyme Activation
- Fibroblasts/drug effects
- Fibroblasts/enzymology
- Genetic Complementation Test
- Humans
- Insulin/pharmacology
- Isoenzymes/chemistry
- Isoenzymes/genetics
- Isoenzymes/physiology
- MAP Kinase Signaling System
- Macromolecular Substances
- Mice
- Mice, Knockout
- Mutagenesis, Site-Directed
- Phosphorylation
- Protein Interaction Mapping
- Protein Processing, Post-Translational
- Protein Serine-Threonine Kinases
- Protein Tyrosine Phosphatase, Non-Receptor Type 2
- Protein Tyrosine Phosphatases/chemistry
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/physiology
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-akt
- Receptor, Insulin/drug effects
- Receptor, Insulin/metabolism
- Recombinant Fusion Proteins/metabolism
- Signal Transduction/drug effects
Collapse
Affiliation(s)
- Sandra Galic
- Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | | | | | | | | | | | | |
Collapse
|
44
|
Abstract
We have investigated the regulation of protein tyrosine phosphatases (PTPs) by reactive oxygen species (ROS) in a cellular environment. We demonstrate that multiple PTPs were reversibly oxidized and inactivated following treatment of Rat-1 cells with H(2)O(2) and that inhibition of PTP function was important for ROS-induced mitogenesis. Furthermore, we show transient oxidation of the SH2 domain containing PTP, SHP-2, in response to PDGF that requires association with the PDGFR. Our results indicate that SHP-2 inhibits PDGFR signaling and suggest a mechanism by which autophosphorylation of the PDGFR occurs despite its association with SHP-2. The data suggest that several PTPs may be regulated by oxidation and that characterization of this process may define novel links between specific PTPs and particular signaling pathways in vivo.
Collapse
Affiliation(s)
- Tzu-Ching Meng
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | | | | |
Collapse
|
45
|
Arevalo I, Ward B, Miller R, Meng TC, Najar E, Alvarez E, Matlashewski G, Llanos-Cuentas A. Successful treatment of drug-resistant cutaneous leishmaniasis in humans by use of imiquimod, an immunomodulator. Clin Infect Dis 2001; 33:1847-51. [PMID: 11692295 DOI: 10.1086/324161] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2001] [Revised: 06/28/2001] [Indexed: 11/04/2022] Open
Abstract
Treatment failures for leishmaniasis with pentavalent antimonials, including meglumine antimonate, are increasingly common in many endemic areas. Imiquimod (Aldara; 3M Pharmaceuticals) is a novel immune response-activating compound, approved by the United States Food and Drug Administration, that is currently used to treat cervical warts and has been shown to activate macrophage killing of Leishmania species. Therefore, an open-label, prospective study was conducted of combined imiquimod plus meglumine antimonate therapy in 12 patients with cutaneous leishmaniasis who had previously not responded to meglumine antimonate therapy. All of the patients responded well to this combination therapy, and 90% were found to be cured at the 6-month follow-up period.
Collapse
Affiliation(s)
- I Arevalo
- Department of Microbiology and Immunology, McGill University, and Department of Tropical Medicine, McGill University Hospital Complex, Montreal, Canada
| | | | | | | | | | | | | | | |
Collapse
|
46
|
Lin MF, Lee MS, Zhou XW, Andressen JC, Meng TC, Johansson SL, West WW, Taylor RJ, Anderson JR, Lin FF. Decreased expression of cellular prostatic acid phosphatase increases tumorigenicity of human prostate cancer cells. J Urol 2001; 166:1943-50. [PMID: 11586265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
PURPOSE Understanding cell proliferation regulation in hormone refractory prostate cancer may provide answers for novel solutions. Protein tyrosine phosphatases have been thought to have key roles in regulating cell proliferation and be involved in oncogenesis, although to our knowledge their functional roles in human prostate cancer remain unknown. Human prostatic acid phosphatase (PAcP), a major phosphatase in prostate epithelium, has been shown to function as a neutral protein tyrosine phosphatase in these cells. We evaluated the biological significance of cellular prostatic acid phosphatase expression in human prostate cancer cells. MATERIALS AND METHODS Immunohistochemical testing of human prostate cancer archival specimens was done to evaluate the expression of cellular PAcP. Immunoprecipitation and immunoblotting were performed to determine cellular PAcP and SH2 domain-bearing tyrosine phosphatase-1 levels as well as tyrosine phosphorylation of c-ErbB-2/neu in different human prostate cancer cells. The biological behavior of LNCaP derivative sublines was characterized in vitro and in vivo by soft agar analysis and xenograft animal inoculation. RESULTS Immunohistochemical staining of human prostate clearly showed that cellular levels of PAcP significantly decreases in prostate cancer cells (p <0.001). The results of biochemical characterization revealed that the cellular level of PAcP but not SHP-1, another differentiation associated protein tyrosine phosphatase, consistently correlated negatively with the growth of several human prostate cancer cell lines. Reintroducing cellular PAcP activity in prostate cancer cells by PAcP complementary DNA transfection resulted in decreased tyrosine phosphorylation of c-ErbB-2/neu, decreased proliferation rates in culture as well as decreased anchorage independent growth in soft agar. The xenograft animal model demonstrated that a higher tumor growth rate as well as larger size is associated with a lower level of cellular PAcP. CONCLUSIONS Cellular PAcP can down-regulate prostate cancer cell growth, at least partially by dephosphorylating c-ErbB-2/neu. Therefore, decreased cellular PAcP expression in cancer cells may be involved in prostate cancer progression.
Collapse
Affiliation(s)
- M F Lin
- Department of Biochemistry, College of Medicine, University of Nebraska Medical Center and Omaha Veterans Administration Medical Center, Omaha, Nebraska, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Spruance SL, Tyring SK, Smith MH, Meng TC. Application of a topical immune response modifier, resiquimod gel, to modify the recurrence rate of recurrent genital herpes: a pilot study. J Infect Dis 2001; 184:196-200. [PMID: 11424018 DOI: 10.1086/322007] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2000] [Revised: 03/27/2001] [Indexed: 11/04/2022] Open
Abstract
Resiquimod (R-848), a topically active immune response modifier, induced production of interferon-alpha and interleukin-12 in cultured blood mononuclear cells and decreased genital herpes recurrences in an animal model. In this study, 52 patients with frequently recurrent genital herpes applied topical resiquimod gel 0.01% (twice or thrice weekly) or 0.05% (once or twice weekly) or vehicle gel to herpes lesions for 3 weeks. During the 6-month observation period after treatment, median days to first recurrence in the pooled resiquimod group was 169 days, compared with 57 days for the vehicle group (P=.0058). In all, 32% of resiquimod-treated patients completed the observation period without a recurrence, compared with 6% of vehicle-treated patients (P=.039). Resiquimod 0.05% twice weekly produced dose-limiting inflammation at the lesion sites, but the other regimens were well tolerated. Application of resiquimod to genital herpes lesions appeared to reduce the frequency of recurrences.
Collapse
Affiliation(s)
- S L Spruance
- Department of Medicine, School of Medicine, University of Utah, Salt Lake City, UT 84132, USA
| | | | | | | |
Collapse
|
48
|
Meng TC, Lee MS, Lin MF. Interaction between protein tyrosine phosphatase and protein tyrosine kinase is involved in androgen-promoted growth of human prostate cancer cells. Oncogene 2000; 19:2664-77. [PMID: 10851066 DOI: 10.1038/sj.onc.1203576] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Steroid hormones play key roles in regulating cell proliferation and differentiation in targeting tissues. However, in advanced cancers, the steroid hormone regulation is frequently attenuated through a yet unknown mechanism even in the presence of functional steroid hormone receptors. We investigate the functional role of tyrosine phosphorylation signaling in the hormone-refractory growth of human prostate tumors. Initial studies demonstrate that the androgen-responsive phenotype of human prostate cancer cells associates with a low phosphotyrosine (p-Tyr) level of ErbB-2, which is regulated by cellular prostatic acid phosphatase (PAcP), a protein tyrosine phosphatase. In prostate cancer cells, the p-Tyr level, but not the protein level, of ErbB-2 inversely correlates with the androgen-responsiveness of cell proliferation. Androgen-stimulated cell growth concurs with a down-regulation of cellular PAcP, an elevated p-Tyr level of ErbB-2, and the activation of mitogen-activated protein kinases. Furthermore, only the ErbB-2 inhibitor AG 879, but not the EGFR inhibitor AG 1478, abolishes androgen-induced cell proliferation. Forced expression of ErbB-2 can also attenuate androgen promotion of cell growth. Data taken collectively conclude that in human prostate cancer cells, the tyrosine phosphorylation of ErbB-2 regulated by cellular PAcP plays a key role in regulating androgen-mediated proliferation signaling. Oncogene (2000).
Collapse
Affiliation(s)
- T C Meng
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, NE 68198, USA
| | | | | |
Collapse
|
49
|
Abstract
Encystation of Giardia lamblia is required for survival outside the host, whereas excystation initiates infection. The dormant cyst was considered an adaptation to external survival and passage through the stomach. However, we found previously that trophozoites which had recovered after completion of the life cycle had switched their major variant surface protein (VSP), called TSA 417, but neither the timing nor the molecular mechanism of switching had been elucidated. Here we demonstrate that TSA 417 predominates in cysts, but is downregulated during the stage of excystation that models cyst arrival in the small intestine. Transcripts of new VSPs appear late in encystation, and during and after excystation. Trophozoites appear to prepare for switching during encystation, when the major VSP on the cell surface diminishes and is internalized in lysosome-like vacuoles. As short-range DNA rearrangements were not detected, giardial VSP switching during differentiation appears to resemble the in situ switching of surface glycoproteins in African trypanosomes. We also report a unique extended 15 nucleotide polyadenylation signal in all VSP transcripts, but not in other known giardial genes. Antigenic variation during encystation-excystation may be a novel form of immune evasion that could help explain the common occurrence of reinfection by Giardia and other parasites with similar life cycles.
Collapse
Affiliation(s)
- S G Svärd
- Department of Pathology, University of California at San Diego, 92103-8416, USA
| | | | | | | | | |
Collapse
|
50
|
Meng TC, Lin MF. Tyrosine phosphorylation of c-ErbB-2 is regulated by the cellular form of prostatic acid phosphatase in human prostate cancer cells. J Biol Chem 1998; 273:22096-104. [PMID: 9705354 DOI: 10.1074/jbc.273.34.22096] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human prostatic acid phosphatase (PAcP) is a prostate epithelium-specific differentiation antigen. In prostate carcinomas, the cellular PAcP is decreased. We investigated its functional role in these cells. Several lines of evidence support the hypothesis that cellular PAcP functions as a neutral protein-tyrosine phosphatase and is involved in regulating prostate cell growth. In this study, we identify its in vivo substrate. Our results demonstrated that, in different human prostate cancer cell lines, the phosphotyrosine (Tyr(P)) level of a 185-kDa phosphoprotein (pp185) inversely correlates with the cellular activity of PAcP. On SDS-PAGE, this pp185 co-migrates with the c-ErbB-2 oncoprotein. Immunodepletion experiments revealed that c-ErbB-2 protein is the major pp185 in cells. Results from subclones of LNCaP cells indicated the lower the cellular PAcP activity, the higher the Tyr(P) levels of c-ErbB-2. This inverse correlation was further observed in PAcP cDNA-transfected cells. In clone 33 LNCaP cells, L-(+)-tartrate suppresses the cellular PAcP activity and causes an elevated Tyr(P) level of c-ErbB-2 protein. Epidermal growth factor stimulates the proliferation of LNCaP cells, which concurs with a decreased cellular PAcP activity as well as an increased Tyr(P) level of c-ErbB-2. Biochemically, PAcP dephosphorylates c-ErbB-2 at pH 7.0. The results thus suggest that cellular PAcP down-regulates prostate cell growth by dephosphorylating Tyr(P) on c-ErbB-2 oncoprotein in those cells.
Collapse
Affiliation(s)
- T C Meng
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA
| | | |
Collapse
|