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Somanath PR, Chernoff J, Cummings BS, Prasad SM, Homan HD. Targeting P21-Activated Kinase-1 for Metastatic Prostate Cancer. Cancers (Basel) 2023; 15:cancers15082236. [PMID: 37190165 DOI: 10.3390/cancers15082236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/06/2023] [Accepted: 04/09/2023] [Indexed: 05/17/2023] Open
Abstract
Metastatic prostate cancer (mPCa) has limited therapeutic options and a high mortality rate. The p21-activated kinase (PAK) family of proteins is important in cell survival, proliferation, and motility in physiology, and pathologies such as infectious, inflammatory, vascular, and neurological diseases as well as cancers. Group-I PAKs (PAK1, PAK2, and PAK3) are involved in the regulation of actin dynamics and thus are integral for cell morphology, adhesion to the extracellular matrix, and cell motility. They also play prominent roles in cell survival and proliferation. These properties make group-I PAKs a potentially important target for cancer therapy. In contrast to normal prostate and prostatic epithelial cells, group-I PAKs are highly expressed in mPCA and PCa tissue. Importantly, the expression of group-I PAKs is proportional to the Gleason score of the patients. While several compounds have been identified that target group-I PAKs and these are active in cells and mice, and while some inhibitors have entered human trials, as of yet, none have been FDA-approved. Probable reasons for this lack of translation include issues related to selectivity, specificity, stability, and efficacy resulting in side effects and/or lack of efficacy. In the current review, we describe the pathophysiology and current treatment guidelines of PCa, present group-I PAKs as a potential druggable target to treat mPCa patients, and discuss the various ATP-competitive and allosteric inhibitors of PAKs. We also discuss the development and testing of a nanotechnology-based therapeutic formulation of group-I PAK inhibitors and its significant potential advantages as a novel, selective, stable, and efficacious mPCa therapeutic over other PCa therapeutics in the pipeline.
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Affiliation(s)
- Payaningal R Somanath
- Department of Clinical & Administrative Pharmacy, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA
- MetasTx LLC, Basking Ridge, NJ 07920, USA
| | - Jonathan Chernoff
- MetasTx LLC, Basking Ridge, NJ 07920, USA
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Brian S Cummings
- MetasTx LLC, Basking Ridge, NJ 07920, USA
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA
| | - Sandip M Prasad
- Morristown Medical Center, Atlantic Health System, Morristown, NJ 07960, USA
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Barraza-Núñez N, Pérez-Núñez R, Gaete-Ramírez B, Barrios-Garrido A, Arriagada C, Poksay K, John V, Barnier JV, Cárdenas AM, Caviedes P. Pharmacological Inhibition of p-21 Activated Kinase (PAK) Restores Impaired Neurite Outgrowth and Remodeling in a Cellular Model of Down Syndrome. Neurotox Res 2023; 41:256-269. [PMID: 36867391 DOI: 10.1007/s12640-023-00638-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 12/27/2022] [Accepted: 02/10/2023] [Indexed: 03/04/2023]
Abstract
Down syndrome (DS) is characterized by the trisomy of chromosome 21 and by cognitive deficits that have been related to neuronal morphological alterations in humans, as well as in animal models. The gene encoding for amyloid precursor protein (APP) is present in autosome 21, and its overexpression in DS has been linked to neuronal dysfunction, cognitive deficit, and Alzheimer's disease-like dementia. In particular, the neuronal ability to extend processes and branching is affected. Current evidence suggests that APP could also regulate neurite growth through its role in the actin cytoskeleton, in part by influencing p21-activated kinase (PAK) activity. The latter effect is carried out by an increased abundance of the caspase cleavage-released carboxy-terminal C31 fragment. In this work, using a neuronal cell line named CTb, which derived from the cerebral cortex of a trisomy 16 mouse, an animal model of human DS, we observed an overexpression of APP, elevated caspase activity, augmented cleavage of the C-terminal fragment of APP, and increased PAK1 phosphorylation. Morphometric analyses showed that inhibition of PAK1 activity with FRAX486 increased the average length of the neurites, the number of crossings per Sholl ring, the formation of new processes, and stimulated the loss of processes. Considering our results, we propose that PAK hyperphosphorylation impairs neurite outgrowth and remodeling in the cellular model of DS, and therefore we suggest that PAK1 may be a potential pharmacological target.
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Affiliation(s)
- Natalia Barraza-Núñez
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Ramón Pérez-Núñez
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Belén Gaete-Ramírez
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Alejandra Barrios-Garrido
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Christian Arriagada
- Department of Anatomy & Forensic Medicine, Faculty of Medicine, University of Chile, Santiago, Chile
| | | | - Varghese John
- Department of Neurology, Easton Center for Alzheimer's Disease Research, University of California, Los Angeles, CA, USA
| | - Jean-Vianney Barnier
- Neuroscience Paris-Saclay Institute, UMR 9197, CNRS-Université Paris-Saclay, Gif-Sur-Yvette, France
| | | | - Pablo Caviedes
- Program of Molecular & Clinical Pharmacology, ICBM, Faculty of Medicine, University of Chile, Santiago, Chile.
- Center for Biotechnology & Bioengineering (CeBiB), Department of Chemical Engineering, Biotechnology & Materials, Faculty of Physical & Mathematical Sciences, University of Chile, Santiago, Chile.
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Wang X, Xiao Y, Dong Y, Wang Z, Yi J, Wang J, Wang X, Zhou H, Zhang L, Shi Y. A20 interacts with mTORC2 to inhibit the mTORC2/Akt/Rac1 signaling axis in hepatocellular carcinoma cells. Cancer Gene Ther 2023; 30:424-436. [PMID: 36411371 DOI: 10.1038/s41417-022-00562-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 11/01/2022] [Accepted: 11/08/2022] [Indexed: 11/23/2022]
Abstract
A20 acts as a tumor suppressor in hepatocellular carcinoma, especially inhibiting metastasis of the malignant cells. However, the mechanisms whereby A20 plays the inhibitory roles are not understood completely. Rac1 signaling is essential for cell migration in hepatocellular carcinoma metastasis. Nevertheless, it is not known whether and how A20 inhibits Rac1 signaling to suppress the migration of hepatocellular carcinoma cell. Thereby, we analyzed the relationship between A20 and Rac1 activation, as well as the activity of Akt and mTORC2, two signaling components upstream of Rac1, using gain and loss of function experiments. We found that the overexpression of A20 repressed, while the knockdown or knockout of A20 promoted, the activation of Rac1, Akt and mTORC2 in hepatocellular carcinoma cells. Moreover, the inhibitory effect of A20 on the mTORC2/Akt/Rac1 signaling axis was due to the interaction between A20 and mTORC2 complex. The binding of A20 to mTORC2 was mediated by the ZnF7 domain of A20 and M1 ubiquitin chain in the mTORC2 complex. Furthermore, A20 inhibited metastasis of hepatocellular carcinoma cells via restraining mTORC2 in a hepatocellular carcinoma xenograft mouse model. These findings revealed the relationship between A20 and mTORC2, and explained the molecular mechanisms of A20 in inhibition of hepatocellular carcinoma metastasis.
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Affiliation(s)
- Xinyu Wang
- Department of Immunology and Shandong Key Laboratory of Infection and Immunity, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Ying Xiao
- Laboratory of Cellular and Molecular Medicine, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Yanlei Dong
- Department of Immunology and Shandong Key Laboratory of Infection and Immunity, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Zhida Wang
- Department of Clinical Laboratory, Shandong Second Provincial General Hospital, Jinan, China
| | - Jing Yi
- Department of Immunology and Shandong Key Laboratory of Infection and Immunity, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Jianing Wang
- Department of Immunology and Shandong Key Laboratory of Infection and Immunity, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Xiaoyan Wang
- Department of Immunology and Shandong Key Laboratory of Infection and Immunity, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Huaiyu Zhou
- Department of Pathogen Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Lining Zhang
- Department of Immunology and Shandong Key Laboratory of Infection and Immunity, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Yongyu Shi
- Department of Immunology and Shandong Key Laboratory of Infection and Immunity, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.
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Minor Kinases with Major Roles in Cytokinesis Regulation. Cells 2022; 11:cells11223639. [PMID: 36429067 PMCID: PMC9688779 DOI: 10.3390/cells11223639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/07/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022] Open
Abstract
Cytokinesis, the conclusive act of cell division, allows cytoplasmic organelles and chromosomes to be faithfully partitioned between two daughter cells. In animal organisms, its accurate regulation is a fundamental task for normal development and for preventing aneuploidy. Cytokinesis failures produce genetically unstable tetraploid cells and ultimately result in chromosome instability, a hallmark of cancer cells. In animal cells, the assembly and constriction of an actomyosin ring drive cleavage furrow ingression, resulting in the formation of a cytoplasmic intercellular bridge, which is severed during abscission, the final event of cytokinesis. Kinase-mediated phosphorylation is a crucial process to orchestrate the spatio-temporal regulation of the different stages of cytokinesis. Several kinases have been described in the literature, such as cyclin-dependent kinase, polo-like kinase 1, and Aurora B, regulating both furrow ingression and/or abscission. However, others exist, with well-established roles in cell-cycle progression but whose specific role in cytokinesis has been poorly investigated, leading to considering these kinases as "minor" actors in this process. Yet, they deserve additional attention, as they might disclose unexpected routes of cell division regulation. Here, we summarize the role of multifunctional kinases in cytokinesis with a special focus on those with a still scarcely defined function during cell cleavage. Moreover, we discuss their implication in cancer.
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Huang CH, Wang FT, Chan WH. Role of caspase-3-cleaved/activated PAK2 in brusatol-triggered apoptosis of human lung cancer A549 cells. Toxicol Res (Camb) 2022; 11:791-803. [PMID: 36337251 PMCID: PMC9623572 DOI: 10.1093/toxres/tfac057] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 09/01/2023] Open
Abstract
Brusatol, a major quassinoid extract of Bruceae fructus, is an important bioactive component with antineoplastic capacity. Several beneficial pharmacological and biological properties of brusatol have been uncovered to date, including anti-inflammatory, anticolitis, antimalarial, and anticancer activities. To confer anticancer benefits, brusatol is reported to effectively inhibit the Nrf2-mediated antioxidant response and trigger apoptotic signaling. In this study, we investigated the regulatory mechanisms underlying apoptotic processes in brusatol-treated A549 cells in detail. Our experiments showed that brusatol induces cell death through intracellular ROS-triggered mitochondria-dependent apoptotic events and does not involve necrosis. Mechanistically, p21-activated protein kinase 2 (PAK2) was cleaved by caspase-3 to generate an activated p34 fragment involved in brusatol-induced apoptosis of A549 cells. Notably, PAK2 knockdown led to downregulation of caspase-3-mediated PAK2 activity, in turn, effectively attenuating brusatol-induced apoptosis, highlighting a crucial role of caspase-3-activated PAK2 in this process. Moreover, knockdown of PAK2 resulted in significant inhibition of c-Jun N-terminal kinase (JNK) activity in brusatol-treated A549 cells, clearly suggesting that JNK serves as a downstream substrate of caspase-3-cleaved/activated PAK2 in the apoptotic cascade. SP600125, a specific JNK inhibitor, significantly suppressed brusatol-induced JNK activity but only partially prevented apoptosis, implying that JNK serves as only one of a number of substrates for PAK2 in the brusatol-triggered apoptotic cascade. Based on the collective results, we propose a signaling cascade model for brusatol-induced apoptosis in human A549 cells involving ROS, caspases, PAK2, and JNK.
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Affiliation(s)
- Chien-Hsun Huang
- Department of Obstetrics and Gynecology, Taoyuan General Hospital, Ministry of Health & Welfare, Zhongshan Road, Taoyuan District, Taoyuan City 33004, Taiwan
| | - Fu-Ting Wang
- Rehabilitation and Technical Aid Center, Taipei Veterans General Hospital, Section 2, Shipai Road, Beitou District, Taipei City 11217, Taiwan
| | - Wen-Hsiung Chan
- Department of Bioscience Technology and Center for Nanotechnology, Chung Yuan Christian University, Zhongbei Road, Zhongli District, Taoyuan City 32023, Taiwan
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Lakshmanan S, Rajendran R, Jayagandhi S, Rajendran R, Palanisamy T, Manimaran V, Janani Marianne A. Expression of Marker PAK1 in Sinonasal Polyposis. Indian J Otolaryngol Head Neck Surg 2022; 74:1694-1700. [PMID: 36452523 PMCID: PMC9702192 DOI: 10.1007/s12070-021-02822-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 08/15/2021] [Indexed: 10/20/2022] Open
Abstract
Introduction Chronic rhinosinusitis with nasal polyposis involves mucosal lining of nose and paranasal sinuses. Numerous studies studied the mechanism leading to sinonasal polyposis. We attempted study the inflammatory mechanisms responsible for the recruitment and activation of leukocytes. Aim To study and compare the expression of the immunohistochemistry marker PAK1 in sinonasal polyposis and normal nasal mucosa. Material and Methods Prospective observational study done by comparing two groups of 30 each with Group A comprises Sinonasal polyposis and Group B comprises normal nasal mucosa. The specimens were subjected to PAK1 immunohistochemical staining. Results Immunihistrochemical staining showed higher intensity stain in sinonasal polyp when compared to normal nasal mucosa. Conclusion The upregulation of PAK1 in sinonasal polyposis when compared to normal nasal mucosa may indicate an increased cellular proliferation and turnover in the background of chronic inflammation.
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Affiliation(s)
- Somu Lakshmanan
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
| | | | - Sathishkumar Jayagandhi
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
| | | | - Thirunavukarasu Palanisamy
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
| | - Vinoth Manimaran
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
| | - A. Janani Marianne
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
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Li X, Li F. p21-Activated Kinase: Role in Gastrointestinal Cancer and Beyond. Cancers (Basel) 2022; 14:cancers14194736. [PMID: 36230657 PMCID: PMC9563254 DOI: 10.3390/cancers14194736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/23/2022] [Accepted: 09/23/2022] [Indexed: 11/23/2022] Open
Abstract
Simple Summary Gastrointestinal tumors are the most common tumors with a high mortality rate worldwide. Numerous protein kinases have been studied in anticipation of finding viable tumor therapeutic targets, including PAK. PAK is a serine/threonine kinase that plays an important role in the malignant phenotype of tumors. The function of PAK in tumors is highlighted in cell proliferation, survival, motility, tumor cell plasticity and the tumor microenvironment, therefore providing a new possible target for clinical tumor therapy. Based on the current research works of PAK, we summarize and analyze the PAK features and signaling pathways in cells, especially the role of PAK in gastrointestinal tumors, thereby hoping to provide a theoretical basis for both the future studies of PAK and potential tumor therapeutic targets. Abstract Gastrointestinal tumors are the most common tumors, and they are leading cause of cancer deaths worldwide, but their mechanisms are still unclear, which need to be clarified to discover therapeutic targets. p21-activating kinase (PAK), a serine/threonine kinase that is downstream of Rho GTPase, plays an important role in cellular signaling networks. According to the structural characteristics and activation mechanisms of them, PAKs are divided into two groups, both of which are involved in the biological processes that are critical to cells, including proliferation, migration, survival, transformation and metabolism. The biological functions of PAKs depend on a large number of interacting proteins and the signaling pathways they participate in. The role of PAKs in tumors is manifested in their abnormality and the consequential changes in the signaling pathways. Once they are overexpressed or overactivated, PAKs lead to tumorigenesis or a malignant phenotype, especially in tumor invasion and metastasis. Recently, the involvement of PAKs in cellular plasticity, stemness and the tumor microenvironment have attracted attention. Here, we summarize the biological characteristics and key signaling pathways of PAKs, and further analyze their mechanisms in gastrointestinal tumors and others, which will reveal new therapeutic targets and a theoretical basis for the clinical treatment of gastrointestinal cancer.
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Nailwal NP, Doshi GM. Role of intracellular signaling pathways and their inhibitors in the treatment of inflammation. Inflammopharmacology 2021; 29:617-640. [PMID: 34002330 DOI: 10.1007/s10787-021-00813-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/24/2021] [Indexed: 12/11/2022]
Abstract
Inflammation is not only a defense mechanism of the innate immune system against invaders, but it is also involved in the pathogenesis of many diseases such as atherosclerosis, thrombosis, diabetes, epilepsy, and many neurodegenerative disorders. The World Health Organization (WHO) reports worldwide estimates of people (9.6% in males and 18.0% in females) aged over 60 years, suffering from symptomatic osteoarthritis, and around 339 million suffering from asthma. Other chronic inflammatory diseases, such as ulcerative colitis and Crohn's disease are also highly prevalent. The existing anti-inflammatory agents, both non-steroidal and steroidal, are highly effective; however, their prolonged use is marred by the severity of associated side effects. A holistic approach to ensure patient compliance requires understanding the pathophysiology of inflammation and exploring new targets for drug development. In this regard, various intracellular cell signaling pathways and their signaling molecules have been identified to be associated with inflammation. Therefore, chemical inhibitors of these pathways may be potential candidates for novel anti-inflammatory drug approaches. This review focuses on the anti-inflammatory effect of these inhibitors (for JAK/STAT, MAPK, and mTOR pathways) describing their mechanism of action through literature search, current patents, and molecules under clinical trials.
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Affiliation(s)
- Namrata P Nailwal
- Department of Pharmacology, SVKM's Dr. Bhanuben Nanavati College of Pharmacy, Mithibai Campus, Vile Parle (W), V. M. Road, 400056, Mumbai, India
| | - Gaurav M Doshi
- Department of Pharmacology, SVKM's Dr. Bhanuben Nanavati College of Pharmacy, Mithibai Campus, Vile Parle (W), V. M. Road, 400056, Mumbai, India.
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Machin PA, Tsonou E, Hornigold DC, Welch HCE. Rho Family GTPases and Rho GEFs in Glucose Homeostasis. Cells 2021; 10:cells10040915. [PMID: 33923452 PMCID: PMC8074089 DOI: 10.3390/cells10040915] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/11/2021] [Accepted: 04/13/2021] [Indexed: 12/17/2022] Open
Abstract
Dysregulation of glucose homeostasis leading to metabolic syndrome and type 2 diabetes is the cause of an increasing world health crisis. New intriguing roles have emerged for Rho family GTPases and their Rho guanine nucleotide exchange factor (GEF) activators in the regulation of glucose homeostasis. This review summates the current knowledge, focusing in particular on the roles of Rho GEFs in the processes of glucose-stimulated insulin secretion by pancreatic β cells and insulin-stimulated glucose uptake into skeletal muscle and adipose tissues. We discuss the ten Rho GEFs that are known so far to regulate glucose homeostasis, nine of which are in mammals, and one is in yeast. Among the mammalian Rho GEFs, P-Rex1, Vav2, Vav3, Tiam1, Kalirin and Plekhg4 were shown to mediate the insulin-stimulated translocation of the glucose transporter GLUT4 to the plasma membrane and/or insulin-stimulated glucose uptake in skeletal muscle or adipose tissue. The Rho GEFs P-Rex1, Vav2, Tiam1 and β-PIX were found to control the glucose-stimulated release of insulin by pancreatic β cells. In vivo studies demonstrated the involvement of the Rho GEFs P-Rex2, Vav2, Vav3 and PDZ-RhoGEF in glucose tolerance and/or insulin sensitivity, with deletion of these GEFs either contributing to the development of metabolic syndrome or protecting from it. This research is in its infancy. Considering that over 80 Rho GEFs exist, it is likely that future research will identify more roles for Rho GEFs in glucose homeostasis.
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Affiliation(s)
- Polly A. Machin
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; (P.A.M.); (E.T.)
| | - Elpida Tsonou
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; (P.A.M.); (E.T.)
- Bioscience Metabolism, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Cambridge CB22 3AT, UK;
| | - David C. Hornigold
- Bioscience Metabolism, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Cambridge CB22 3AT, UK;
| | - Heidi C. E. Welch
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; (P.A.M.); (E.T.)
- Correspondence: ; Tel.: +44-(0)1223-496-596
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Signaling cross-talk during development: Context-specific networking of Notch, NF-κB and JNK signaling pathways in Drosophila. Cell Signal 2021; 82:109937. [PMID: 33529757 DOI: 10.1016/j.cellsig.2021.109937] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 01/08/2023]
Abstract
Multicellular organisms depend on a handful of core signaling pathways that regulate a variety of cell fate choices. Often these relatively simple signals integrate to form a large and complex signaling network to achieve a distinct developmental fate in a context-specific manner. Various pathway-dependent and independent events control the assembly of signaling complexes. Notch pathway is one such conserved signaling mechanism that integrates with other signaling pathways to exhibit a context-dependent pleiotropic output. To understand how Notch signaling provides a spectrum of distinct outputs, it is important to understand various regulatory switches involved in mediating signaling cross-talk of Notch with other pathways. Here, we review our current understanding as to how Notch signal integrates with JNK and NF-κB signaling pathways in Drosophila to regulate various developmental events such as sensory organ precursor formation, innate immunity, dorsal closure, establishment of planar cell polarity as well as during proliferation and tumor progression. We highlight the importance of conserved signaling molecules during these cross-talks and debate further possibilities of novel switches that may be involved in mediating these cross-talk events.
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Han J, Wu J, Silke J. An overview of mammalian p38 mitogen-activated protein kinases, central regulators of cell stress and receptor signaling. F1000Res 2020; 9. [PMID: 32612808 PMCID: PMC7324945 DOI: 10.12688/f1000research.22092.1] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/18/2020] [Indexed: 12/19/2022] Open
Abstract
The p38 family is a highly evolutionarily conserved group of mitogen-activated protein kinases (MAPKs) that is involved in and helps co-ordinate cellular responses to nearly all stressful stimuli. This review provides a succinct summary of multiple aspects of the biology, role, and substrates of the mammalian family of p38 kinases. Since p38 activity is implicated in inflammatory and other diseases, we also discuss the clinical implications and pharmaceutical approaches to inhibit p38.
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Affiliation(s)
- Jiahuai Han
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - Jianfeng Wu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, 361005, China
| | - John Silke
- The Walter and Eliza Hall Institute, IG Royal Parade, Parkville, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria, 3050, Australia
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Biswal J, Jayaprakash P, Suresh Kumar R, Venkatraman G, Poopandi S, Rangasamy R, Jeyaraman J. Identification of Pak1 inhibitors using water thermodynamic analysis. J Biomol Struct Dyn 2019; 38:13-31. [PMID: 30661460 DOI: 10.1080/07391102.2019.1567393] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
p21-activated kinases (Paks) play an integral component in various cellular diverse processes. The full activation of Pak is dependent upon several serine residues present in the N-terminal region, a threonine present at the activation loop, and finally the phosphorylation of these residues ensure the complete activation of Pak1. The present study deals with the identification of novel potent candidates of Pak1 using computational methods as anti-cancer compounds. A diverse energy based pharmacophore (e-pharmacophore) was developed using four co-crystal inhibitors of Pak1 having pharmacophore features of 5 (DRDRR), 6 (DRHADR), and 7 (RRARDRP and DRRDADH) hypotheses. These models were used for rigorous screening against e-molecule database. The obtained hits were filtered using ADME/T and molecular docking to identify the high affinity binders. These hits were subjected to hierarchical clustering using dendritic fingerprint inorder to identify structurally diverse molecules. The diverse hits were scored against generated water maps to obtain WM/MM ΔG binding energy. Furthermore, molecular dynamics simulation and density functional theory calculations were performed on the final hits to understand the stability of the complexes. Five structurally diverse novel Pak1 inhibitors (4835785, 32198676, 32407813, 76038049, and 32945545) were obtained from virtual screening, water thermodynamics and WM/MM ΔG binding energy. All hits revealed similar mode of binding pattern with the hinge region residues replacing the unstable water molecules in the binding site. The obtained novel hits could be used as a platform to design potent drugs that could be experimentally tested against cancer patients having increased Pak1 expression.
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Affiliation(s)
- Jayashree Biswal
- Department of Bioinformatics, Science Block Alagappa University, Karaikudi Tamil Nadu, India
| | - Prajisha Jayaprakash
- Department of Bioinformatics, Science Block Alagappa University, Karaikudi Tamil Nadu, India
| | - Rayala Suresh Kumar
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
| | - Ganesh Venkatraman
- Department of Human Genetics College of Biomedical Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India
| | - Saritha Poopandi
- Department of Bioinformatics, Science Block Alagappa University, Karaikudi Tamil Nadu, India
| | - Raghu Rangasamy
- Department of Bioinformatics, Science Block Alagappa University, Karaikudi Tamil Nadu, India
| | - Jeyakanthan Jeyaraman
- Department of Bioinformatics, Science Block Alagappa University, Karaikudi Tamil Nadu, India
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Cloning and functional characterization of human Pak1 promoter by steroid hormones. Gene 2017; 646:120-128. [PMID: 29274909 DOI: 10.1016/j.gene.2017.12.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 10/29/2017] [Accepted: 12/20/2017] [Indexed: 12/21/2022]
Abstract
P21-activated kinase 1 (Pak1) is known to be involved in a plethora of functions including cell growth, survival and can lead to cell transformation and tumor progression especially in breast tissue. Multiple studies have shown Pak1 dysregulation as a change in DNA copy number as well as gene expression levels, suggesting many regulatory mechanisms at transcriptional and translational level. However, very little is known about the transcriptional regulation of the human Pak1 promoter. Here, we focus on Pak1 promoter regulation by steroid hormones along with their respective receptors that are also crucial players in breast tissue function and tumorigenesis. Our results show high Pak1 expression in breast cancer cell lines and in breast tumor tissue. It also suggests that Pak1 is hormone responsive, whose expression can be modulated by steroid hormones namely, estrogen in the form of 17β-estradiol (E2) and progesterone (P4). Sequence analysis of a 3.2kb Pak1 proximal promoter region shows the presence of PRE (progesterone response element) and ERE (estrogen response element) half sites, that were further cloned and characterized. Results from promoter analysis showed that Pak1 promoter activity is mediated by PR via its binding to PRE present on the Pak1 promoter that was further reaffirmed in vitro by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation assay (ChIP). Our results together suggest that it is the PR isoform B regulates Pak1 promoter. To our knowledge, this is the first study to report the detailed characterization and transcriptional regulation of the human Pak1 promoter by steroid hormones.
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14
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Kumar R, Sanawar R, Li X, Li F. Structure, biochemistry, and biology of PAK kinases. Gene 2016; 605:20-31. [PMID: 28007610 DOI: 10.1016/j.gene.2016.12.014] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/24/2016] [Accepted: 12/14/2016] [Indexed: 02/07/2023]
Abstract
PAKs, p21-activated kinases, play central roles and act as converging junctions for discrete signals elicited on the cell surface and for a number of intracellular signaling cascades. PAKs phosphorylate a vast number of substrates and act by remodeling cytoskeleton, employing scaffolding, and relocating to distinct subcellular compartments. PAKs affect wide range of processes that are crucial to the cell from regulation of cell motility, survival, redox, metabolism, cell cycle, proliferation, transformation, stress, inflammation, to gene expression. Understandably, their dysregulation disrupts cellular homeostasis and severely impacts key cell functions, and many of those are implicated in a number of human diseases including cancers, neurological disorders, and cardiac disorders. Here we provide an overview of the members of the PAK family and their current status. We give special emphasis to PAK1 and PAK4, the prototypes of groups I and II, for their profound roles in cancer, the nervous system, and the heart. We also highlight other family members. We provide our perspective on the current advancements, their growing importance as strategic therapeutic targets, and our vision on the future of PAKs.
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Affiliation(s)
- Rakesh Kumar
- Department of Biochemistry and Molecular Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC 20037, USA; Cancer Biology Program, Rajiv Gandhi Center of Biotechnology, Thiruvananthapuram 695014, India.
| | - Rahul Sanawar
- Cancer Biology Program, Rajiv Gandhi Center of Biotechnology, Thiruvananthapuram 695014, India
| | - Xiaodong Li
- Department of Cell Biology, Key Laboratory of Medical Cell Biology, Chinese Ministry of Education, China Medical University, Shenyang 110122, China
| | - Feng Li
- Department of Cell Biology, Key Laboratory of Medical Cell Biology, Chinese Ministry of Education, China Medical University, Shenyang 110122, China.
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15
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Choe CP, Crump JG. Eph-Pak2a signaling regulates branching of the pharyngeal endoderm by inhibiting late-stage epithelial dynamics. Development 2015; 142:1089-94. [PMID: 25725065 DOI: 10.1242/dev.115774] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Branching morphogenesis depends on the precise temporal and spatial control of epithelial dynamics. In the vertebrate head, endodermal branches, called pharyngeal pouches, form through the transient stratification, collective migration and reorganization of epithelial cells into bilayers. Here, we report novel requirements for the EphrinB ligands B2a and B3b, the Ephb4a receptor and the Pak2a kinase in the development of pouches and the posterior facial skeleton that depends on pouches for its segmentation. Time-lapse imaging in zebrafish shows that EphB-Pak2a signaling is required to stabilize pouch epithelial cells at the end of branching morphogenesis. Transgenic rescue experiments further demonstrate that endodermal Eph-ephrin signaling promotes pouch integrity by targeting Pak2a to the plasma membrane, where subsequent activation by Wnt4a-Cdc42 signaling increases junctional E-cadherin in maturing pouches. Integration of Eph-ephrin and Wnt4a signaling through Pak2a thus signals the end of branching morphogenesis by increasing intercellular adhesion that blocks further epithelial rearrangements.
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Affiliation(s)
- Chong Pyo Choe
- Broad CIRM Center, Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - J Gage Crump
- Broad CIRM Center, Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
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16
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Zhao ZS, Manser E. PAK family kinases: Physiological roles and regulation. CELLULAR LOGISTICS 2014; 2:59-68. [PMID: 23162738 PMCID: PMC3490964 DOI: 10.4161/cl.21912] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The p21-activated kinases (PAKs) are a family of Ser/Thr protein kinases that are represented by six genes in humans (PAK 1-6), and are found in all eukaryotes sequenced to date. Genetic and knockdown experiments in frogs, fish and mice indicate group I PAKs are widely expressed, required for multiple tissue development, and particularly important for immune and nervous system function in the adult. The group II PAKs (human PAKs 4-6) are more enigmatic, but their restriction to metazoans and presence at cell-cell junctions suggests these kinases emerged to regulate junctional signaling. Studies of protozoa and fungal PAKs show that they regulate cell shape and polarity through phosphorylation of multiple cytoskeletal proteins, including microtubule binding proteins, myosins and septins. This chapter discusses what we know about the regulation of PAKs and their physiological role in different model organisms, based primarily on gene knockout studies.
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Affiliation(s)
- Zhuo-Shen Zhao
- sGSK Group; Astar Neuroscience Research Partnership; Singapore
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17
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Xu HG, Zhai YX, Chen J, Lu Y, Wang JW, Quan CS, Zhao RX, Xiao X, He Q, Werle KD, Kim HG, Lopez R, Cui R, Liang J, Li YL, Xu ZX. LKB1 reduces ROS-mediated cell damage via activation of p38. Oncogene 2014; 34:3848-59. [PMID: 25263448 PMCID: PMC4377312 DOI: 10.1038/onc.2014.315] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 08/05/2014] [Accepted: 08/06/2014] [Indexed: 12/27/2022]
Abstract
Liver kinase B1 (LKB1, also known as serine/threonine kinase 11, STK11) is a tumor suppressor mutated in Peutz-Jeghers syndrome and in a variety of sporadic cancers. Herein, we demonstrate that LKB1 controls the levels of intracellular reactive oxygen species (ROS) and protects the genome from oxidative damage. Cells lacking LKB1 exhibit markedly increased intracellular ROS levels, excessive oxidation of DNA, increased mutation rates, and accumulation of DNA damage, which are effectively prevented by ectopic expression of LKB1 and by incubation with antioxidant N-acetylcysteine (NAC). The role of LKB1 in suppressing ROS is independent of AMPK, a canonical substrate of LKB1. Instead, under the elevated ROS, LKB1 binds to and maintains the activity of cdc42-PAK1 (p21 activated kinase 1) complex, which triggers the activation of p38 and its downstream signaling targets, such as ATF-2, thereby enhancing the activity of SOD-2 and catalase, two antioxidant enzymes that protect the cells from ROS accumulation, DNA damage, and loss of viability. Our results provide a new paradigm for a non-canonical tumor suppressor function of LKB1 and highlight the importance of targeting ROS signaling as a potential therapeutic strategy for cancer cells lacking LKB1.
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Affiliation(s)
- H-G Xu
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Y-X Zhai
- Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - J Chen
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Y Lu
- Department of Endocrinology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - J-W Wang
- Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - C-S Quan
- Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - R-X Zhao
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - X Xiao
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Q He
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - K D Werle
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - H-G Kim
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - R Lopez
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - R Cui
- Department of Dermatology, Boston University, School of Medicine, Boston, MA, USA
| | - J Liang
- Department of Systems Biology, UT MD Anderson Cancer Center, Houston, TX, USA
| | - Y-L Li
- Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - Z-X Xu
- 1] Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA [2] Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
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18
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Taglieri DM, Ushio-Fukai M, Monasky MM. P21-activated kinase in inflammatory and cardiovascular disease. Cell Signal 2014; 26:2060-9. [PMID: 24794532 DOI: 10.1016/j.cellsig.2014.04.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 04/27/2014] [Indexed: 02/09/2023]
Abstract
P-21 activated kinases, or PAKs, are serine-threonine kinases that serve a role in diverse biological functions and organ system diseases. Although PAK signaling has been the focus of many investigations, still our understanding of the role of PAK in inflammation is incomplete. This review consolidates what is known about PAK1 across several cell types, highlighting the role of PAK1 and PAK2 in inflammation in relation to NADPH oxidase activation. This review explores the physiological functions of PAK during inflammation, the role of PAK in several organ diseases with an emphasis on cardiovascular disease, and the PAK signaling pathway, including activators and targets of PAK. Also, we discuss PAK1 as a pharmacological anti-inflammatory target, explore the potentials and the limitations of the current pharmacological tools to regulate PAK1 activity during inflammation, and provide indications for future research. We conclude that a vast amount of evidence supports the idea that PAK is a central molecule in inflammatory signaling, thus making PAK1 itself a promising prospective pharmacological target.
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Affiliation(s)
- Domenico M Taglieri
- Department of Anesthesia and General Intensive Care Unit, Humanitas Research Hospital, Via Manzoni 56, Rozzano, 20089 (Milano), Italy.
| | - Masuko Ushio-Fukai
- Department of Pharmacology, Center for Lung and Vascular Biology, Center for Cardiovascular Research, University of Illinois at Chicago, 835 S. Wolcott Ave. E403 MSB, M/C868, Chicago, IL 60612, USA.
| | - Michelle M Monasky
- Cardiovascular Research Center, Humanitas Research Hospital, Via Manzoni 113, Rozzano, 20089 (Milano), Italy.
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19
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Chen H, Miao J, Li H, Wang C, Li J, Zhu Y, Wang J, Wu X, Qiao H. Expression and prognostic significance of p21-activated kinase 6 in hepatocellular carcinoma. J Surg Res 2014; 189:81-8. [PMID: 24576777 DOI: 10.1016/j.jss.2014.01.049] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 01/15/2014] [Accepted: 01/24/2014] [Indexed: 12/12/2022]
Abstract
BACKGROUND p21-activated protein kinase (PAK) 6 is a serine-threonine kinase belonging to the PAK family. Previous studies have indicated that abnormal expressions of PAK1, PAK2, and PAK5 played critical roles in hepatocellular carcinoma (HCC). Recent studies suggested that deregulation of PAK6 expression played an important role in oncogenesis. To explore the potential roles of PAK6 in HCC, expression of PAK6 was detected in human HCC specimens. METHODS Immunohistochemistry and Western blot analysis were performed for PAK6 in 121 HCC samples. The data were correlated with clinicopathologic features. The univariate and multivariate survival analyses were also performed to determine their clinical prognostic significance. RESULTS PAK6 was overexpressed in HCC as compared with the adjacent noncancerous liver tissues. High expression of PAK6 was associated with Edmondson-Steiner grade (P = 0.006) and number of tumor nodules (P < 0.001), and PAK6 was positively correlated with proliferation marker Ki-67 (P < 0.01). Univariate analysis suggested that PAK6 expression was associated with poor prognosis (P < 0.001). Multivariate analysis indicated that PAK6 and Ki-67 protein expressions were independent prognostic markers for HCC (P = 0.0245 and 0.0331, respectively). CONCLUSIONS Our results suggest that PAK6 overexpression is involved in the pathogenesis of HCC; it may be an independent poor prognostic factor for HCC.
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Affiliation(s)
- Hongwei Chen
- Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China.
| | - Jinlin Miao
- Department of Magnetic Resonance Imaging, The Fourth People's Hospital of Taizhou, Taizhou, China
| | - Hongchen Li
- Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Chunhua Wang
- Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Junliang Li
- Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Yong Zhu
- Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Jianxin Wang
- Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Xia Wu
- Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China
| | - Hongying Qiao
- Department of Clinical Laboratory, The First Hospital of Qinhuangdao, Qinhuangdao, China
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20
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Singhal R, Kandel ES. The response to PAK1 inhibitor IPA3 distinguishes between cancer cells with mutations in BRAF and Ras oncogenes. Oncotarget 2013; 3:700-8. [PMID: 22869096 PMCID: PMC3443253 DOI: 10.18632/oncotarget.587] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
While new drugs aimed at BRAF-mutated cancers are entering clinical practice, cells and tumors with activating Ras mutations are relatively resistant to those and quite a few other anti-cancer agents. This inspires the effort to reverse this resistance or to uncover new vulnerabilities in such resistant cancers. IPA3 has been originally identified as a small molecule inhibitor of p21-activated protein kinase 1 (PAK1), a candidate therapeutic target in human malignancies. We have tested a battery of melanoma and colon carcinoma cell lines that carry mutations in BRAF, NRAS and KRAS genes and have observed that those with NRAS and KRAS mutations are more sensitive to killing by IPA3. Genetic manipulations suggest that the differential response depends not just on these oncogenes, but also on additional events that were co-selected during tumor evolution. Furthermore, sublethal doses of IPA3 or ectopic expression of dominant-negative PAK1 sensitized Ras-mutated cells to GDC-0897 and AZD6244, which otherwise have reduced efficiency against cells with activated Ras. Dominant-negative PAK1 also reduced the growth of NRAS-mutated cells in confluent cultures, but, unlike IPA3, caused no significant toxicity. Although it remains to be proven that all the effects of IPA3 are exclusively due to inhibition of PAK1, our findings point to the existence of selective vulnerabilities, which are associated with Ras mutations and could be useful for better understanding and treatment of a large subset of tumors.
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Affiliation(s)
- Ruchi Singhal
- Roswell Park Cancer Institute, Department of Cell Stress Biology, Elm and Carlton St., Buffalo, NY 142263, USA
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21
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Wang J, Wu JW, Wang ZX. Structural insights into the autoactivation mechanism of p21-activated protein kinase. Structure 2012; 19:1752-61. [PMID: 22153498 DOI: 10.1016/j.str.2011.10.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 09/04/2011] [Accepted: 10/01/2011] [Indexed: 01/21/2023]
Abstract
p21-activated kinases (PAKs) play an important role in diverse cellular processes. Full activation of PAKs requires autophosphorylation of a critical threonine/serine located in the activation loop of the kinase domain. Here we report crystal structures of the phosphorylated and unphosphorylated PAK1 kinase domain. The phosphorylated PAK1 kinase domain has a conformation typical of all active protein kinases. Interestingly, the structure of the unphosphorylated PAK1 kinase domain reveals an unusual dimeric arrangement expected in an authentic enzyme-substrate complex, in which the activation loop of the putative "substrate" is projected into the active site of the "enzyme." The enzyme is bound to AMP-PNP and has an active conformation, whereas the substrate is empty and adopts an inactive conformation. Thus, the structure of the asymmetric homodimer mimics a trans-autophosphorylation complex, and suggests that unphosphorylated PAK1 could dynamically adopt both the active and inactive conformations in solution.
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Affiliation(s)
- Jue Wang
- MOE Key Laboratory for Protein Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
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22
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Fu D, Yang Y, Xiao Y, Lin H, Ye Y, Zhan Z, Liang L, Yang X, Sun L, Xu H. Role of p21-activated kinase 1 in regulating the migration and invasion of fibroblast-like synoviocytes from rheumatoid arthritis patients. Rheumatology (Oxford) 2012; 51:1170-80. [PMID: 22416254 DOI: 10.1093/rheumatology/kes031] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE To investigate the role of p21-activated kinase 1 (PAK1) in regulating migration, invasion and MMP expression in RA fibroblast-like synoviocytes (FLS). METHODS RA FLS migration and invasion in vitro were measured by the Boyden chamber method. Invasion of RA FLS into cartilage was detected in the severe combined immunodeficiency (SCID) mouse co-implantation model of RA in vivo. PAK1 and MT1-MMP expression were examined by western blotting. ELISA was used to measure the production and activity of MMPs. RESULTS Phosphorylated PAK1 (p-PAK1) protein expression was increased in ex vivo synovial membrane cells from RA patients. Stimulation with IL-1β or TNF-α up-regulated p-PAK1 expression. Inhibition of PAK1 by transfection with dominant negative PAK1 mutant (dnPAK1) reduced in vitro migration and invasion of RA FLS. In the SCID mouse model, RA FLS invasion into cartilage was attenuated by transfection with dnPAK1 in vivo. PAK1 regulated IL-1β-induced production and activity of MMP-13 and MT1-MMP. Inhibition of MMP-13 or MT1-MMP activity also reduced RA FLS invasion. Furthermore, dnPAK1 transfection inhibited c-Jun N-terminal kinase (JNK) activation, but did not affect the activities of extracellular signal-regulated kinases and p38. Inhibition of the JNK activity by chemical inhibitor significantly reduced the migration, invasion and production of MMP-13 and MT1-MMP. CONCLUSION PAK1 plays an important role in regulating the migration, invasion and production and activity of MMPs in RA FLS, which is mediated by the JNK pathway. This suggests a novel strategy targeting PAK1 to prevent joint destruction of RA.
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Affiliation(s)
- Di Fu
- Department of Rheumatology, The First Affiliated Hospital, Sun Yat-sen University, No. 58 Zhongshan Road 2, Guangzhou, Guangdong 510080, P.R. China
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23
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Song H, Wohltmann M, Tan M, Bao S, Ladenson JH, Turk J. Group VIA PLA2 (iPLA2β) is activated upstream of p38 mitogen-activated protein kinase (MAPK) in pancreatic islet β-cell signaling. J Biol Chem 2012; 287:5528-41. [PMID: 22194610 PMCID: PMC3285329 DOI: 10.1074/jbc.m111.285114] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 12/21/2011] [Indexed: 01/09/2023] Open
Abstract
Group VIA phospholipase A(2) (iPLA(2)β) in pancreatic islet β-cells participates in glucose-stimulated insulin secretion and sarco(endo)plasmic reticulum ATPase (SERCA) inhibitor-induced apoptosis, and both are attenuated by pharmacologic or genetic reductions in iPLA(2)β activity and amplified by iPLA(2)β overexpression. While exploring signaling events that occur downstream of iPLA(2)β activation, we found that p38 MAPK is activated by phosphorylation in INS-1 insulinoma cells and mouse pancreatic islets, that this increases with iPLA(2)β expression level, and that it is stimulated by the iPLA(2)β reaction product arachidonic acid. The insulin secretagogue D-glucose also stimulates β-cell p38 MAPK phosphorylation, and this is prevented by the iPLA(2)β inhibitor bromoenol lactone. Insulin secretion induced by d-glucose and forskolin is amplified by overexpressing iPLA(2)β in INS-1 cells and in mouse islets, and the p38 MAPK inhibitor PD169316 prevents both responses. The SERCA inhibitor thapsigargin also stimulates phosphorylation of both β-cell MAPK kinase isoforms and p38 MAPK, and bromoenol lactone prevents both events. Others have reported that iPLA(2)β products activate Rho family G-proteins that promote MAPK kinase activation via a mechanism inhibited by Clostridium difficile toxin B, which we find to inhibit thapsigargin-induced β-cell p38 MAPK phosphorylation. Thapsigargin-induced β-cell apoptosis and ceramide generation are also prevented by the p38 MAPK inhibitor PD169316. These observations indicate that p38 MAPK is activated downstream of iPLA(2)β in β-cells incubated with insulin secretagogues or thapsigargin, that this requires prior iPLA(2)β activation, and that p38 MAPK is involved in the β-cell functional responses of insulin secretion and apoptosis in which iPLA(2)β participates.
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Affiliation(s)
- Haowei Song
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, and
| | - Mary Wohltmann
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, and
| | - Min Tan
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, and
| | - Shunzhong Bao
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, and
| | - Jack H. Ladenson
- the Division of Laboratory and Genomic Medicine, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - John Turk
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, and
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24
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Upregulation of p21-activated Kinase 6 in rat brain cortex after traumatic brain injury. J Mol Histol 2011; 42:195-203. [DOI: 10.1007/s10735-011-9324-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 03/28/2011] [Indexed: 12/30/2022]
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25
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Chan WH. Photodynamic treatment induces an apoptotic pathway involving calcium, nitric oxide, p53, p21-activated kinase 2, and c-Jun N-terminal kinase and inactivates survival signal in human umbilical vein endothelial cells. Int J Mol Sci 2011; 12:1041-59. [PMID: 21541041 PMCID: PMC3083688 DOI: 10.3390/ijms12021041] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 01/25/2011] [Accepted: 02/02/2011] [Indexed: 01/24/2023] Open
Abstract
Photodynamic treatment (PDT) elicits a diverse range of cellular responses, including apoptosis. Previously, we showed that PDT stimulates caspase-3 activity, and subsequent cleavage and activation of p21-activated kinase 2 (PAK2) in human epidermal carcinoma A431 cells. In the current study, pretreatment with nitric oxide (NO) scavengers inhibited PDT-induced mitochondrial membrane potential (MMP) changes, activation of caspase-9, caspase-3, p21-activated protein kinase 2 (PAK2) and c-Jun N-terminal kinase (JNK), and gene expression of p53 and p21 involved in apoptotic signaling. Moreover, PAK2 activity was required for PDT-induced JNK activation and apoptosis. Inhibition of p53 mRNA expression using small interfering RNA (siRNA) additionally blocked activation of PAK2 and apoptosis induced by PDT. Importantly, our data also show that PDT triggers cell death via inactivation of ERK-mediated anti-apoptotic pathway. PDT triggers cell death via inactivation of the HSP90/multi-chaperone complex and subsequent degradation of Ras, further inhibiting anti-apoptotic processes, such as the Ras→ERK signal transduction pathway. Furthermore, we did not observe two-stage JNK activation for regulation of PAK2 activity in the PDT-induced apoptotic pathway in HUVECs, which was reported earlier in A431 cells. Based on the collective results, we have proposed a model for the PDT-triggered inactivation of the survival signal and apoptotic signaling cascade with Rose Bengal (RB), which sequentially involves singlet oxygen, Ca2+, NO, p53, caspase-9, caspase-3, PAK2, and JNK.
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Affiliation(s)
- Wen-Hsiung Chan
- Department of Bioscience Technology and Center for Nanotechnology, Chung Yuan Christian University, Chung Li 32023, Taiwan; E-Mail: ; Tel.: +886-3-2653515
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26
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Kichina JV, Goc A, Al-Husein B, Somanath PR, Kandel ES. PAK1 as a therapeutic target. Expert Opin Ther Targets 2010; 14:703-25. [PMID: 20507214 DOI: 10.1517/14728222.2010.492779] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
IMPORTANCE OF THE FIELD P21-activated kinases (PAKs) are involved in multiple signal transduction pathways in mammalian cells. PAKs, and PAK1 in particular, play a role in such disorders as cancer, mental retardation and allergy. Cell motility, survival and proliferation, the organization and function of cytoskeleton and extracellular matrix, transcription and translation are among the processes affected by PAK1. AREAS COVERED IN THIS REVIEW We discuss the mechanisms that control PAK1 activity, its involvement in physiological and pathophysiological processes, the benefits and the drawbacks of the current tools to regulate PAK1 activity, the evidence that suggests PAK1 as a therapeutic target and the likely directions of future research. WHAT THE READER WILL GAIN The reader will gain a better knowledge and understanding of the areas described above. TAKE HOME MESSAGE PAK1 is a promising therapeutic target in cancer and allergen-induced disorders. Its suitability as a target in vascular, neurological and infectious diseases remains ambiguous. Further advancement of this field requires progress on such issues as the development of specific and clinically acceptable inhibitors, the choice between targeting one or multiple PAK isoforms, elucidation of the individual roles of PAK1 targets and the mechanisms that may circumvent inhibition of PAK1.
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Affiliation(s)
- Julia V Kichina
- Roswell Park Cancer Institute, Department of Cell Stress Biology, Elm and Carlton Streets, Buffalo, NY 14263, USA
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27
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Hsu RM, Tsai MH, Hsieh YJ, Lyu PC, Yu JS. Identification of MYO18A as a novel interacting partner of the PAK2/betaPIX/GIT1 complex and its potential function in modulating epithelial cell migration. Mol Biol Cell 2009; 21:287-301. [PMID: 19923322 PMCID: PMC2808764 DOI: 10.1091/mbc.e09-03-0232] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
MYO18A is found as a novel PAK2 binding partner via βPIX/GIT1. MYO18A-depleted cells showed dramatic changes in shape, actin stress fiber and membrane ruffle formation, and displayed increases in the number and size of focal adhesions and a decrease in cell migration, suggesting an important role of MYO18A in regulating epithelial cell migration. The p21-activated kinase (PAK) 2 is known to be involved in numerous biological functions, including the regulation of actin reorganization and cell motility. To better understand the mechanisms underlying this regulation, we herein used a proteomic approach to identify PAK2-interacting proteins in human epidermoid carcinoma A431 cells. We found that MYO18A, an emerging member of the myosin superfamily, is a novel PAK2 binding partner. Using a siRNA knockdown strategy and in vitro binding assay, we discovered that MYO18A binds to PAK2 through the βPIX/GIT1 complex. Under normal conditions, MYO18A and PAK2 colocalized in lamellipodia and membrane ruffles. Interestingly, knockdown of MYO18A in cells did not prevent formation of the PAK2/βPIX/GIT1 complex, but rather apparently changed its localization to focal adhesions. Moreover, MYO18A-depleted cells showed dramatic changes in morphology and actin stress fiber and membrane ruffle formation and displayed increases in the number and size of focal adhesions. Migration assays revealed that MYO18A-depleted cells had decreased cell motility, and reexpression of MYO18A restored their migration ability. Collectively, our findings indicate that MYO18A is a novel binding partner of the PAK2/βPIX/GIT1 complex and suggest that MYO18A may play an important role in regulating epithelial cell migration via affecting multiple cell machineries.
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Affiliation(s)
- Rae-Mann Hsu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China
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28
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Huang YT, Lai CY, Lou SL, Yeh JM, Chan WH. Activation of JNK and PAK2 is essential for citrinin-induced apoptosis in a human osteoblast cell line. ENVIRONMENTAL TOXICOLOGY 2009; 24:343-356. [PMID: 18767140 DOI: 10.1002/tox.20434] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The mycotoxin citrinin (CTN), a natural contaminant in foodstuffs and animal feeds, exerts cytotoxic and genotoxic effects on various mammalian cells. CTN causes cell injury, including apoptosis. Previous studies by our group showed that CTN triggers apoptosis in mouse embryonic stem cells, as well as embryonic developmental injury. Here, we investigated the precise mechanisms governing this apoptotic effect in osteoblasts. CTN induced apoptotic biochemical changes in a human osteoblast cell line, including activation of c-Jun N-terminal kinase (JNK), loss of mitochondrial membrane potential, and caspase-3 and p21-activated protein kinase 2 (PAK2) activation. Experiments using a JNK-specific inhibitor, SP600125, and antisense oligonucleotides against JNK reduced CTN-induced activation of both JNK and caspase-3 in osteoblasts, indicating that JNK is required for caspase activation in this apoptotic pathway. Experiments using caspase-3 inhibitors and antisense oligonucleotides against PAK2 revealed that active caspase-3 is essential for PAK2 activation. Moreover, both caspase-3 and PAK2 require activation for CTN-induced apoptosis of osteoblasts. Interestingly, CTN stimulates two-stage activation of JNK in human osteoblasts. Early-stage JNK activation is solely ROS-dependent, whereas late-stage activation is dependent on ROS-mediated caspase activity, and regulated by caspase-induced activation of PAK2. On the basis of these results, we propose a signaling cascade model for CTN-induced apoptosis in human osteoblasts involving ROS, JNK, caspases, and PAK2.
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Affiliation(s)
- Yu-Ting Huang
- Department of Bioscience Technology, Center for Nanotechnology, Chung Yuan Christian University, Chung Li, Taiwan
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29
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Inhibition of citrinin-induced apoptotic biochemical signaling in human hepatoma G2 cells by resveratrol. Int J Mol Sci 2009; 10:3338-3357. [PMID: 20111678 PMCID: PMC2812821 DOI: 10.3390/ijms10083338] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 07/27/2009] [Accepted: 07/28/2009] [Indexed: 12/25/2022] Open
Abstract
The mycotoxin citrinin (CTN), a natural contaminant in foodstuffs and animal feeds, exerts cytotoxic and genotoxic effects on various mammalian cells. CTN causes cell injury, including apoptosis, but its precise regulatory mechanisms of action are currently unclear. Resveratrol, a member of the phytoalexin family found in grapes and other dietary plants, possesses antioxidant and anti-tumor properties. In the present study, we examined the effects of resveratrol on apoptotic biochemical events in Hep G2 cells induced by CTN. Resveratrol inhibited CTN-induced ROS generation, activation of JNK, loss of mitochondrial membrane potential (MMP), as well as activation of caspase-9, caspase-3 and PAK2. Moreover, resveratrol and the ROS scavengers, NAC and α-tocopherol, abolished CTN-stimulated intracellular oxidative stress and apoptosis. Active JNK was required for CTN-induced mitochondria-dependent apoptotic biochemical changes, including loss of MMP, and activation of caspases and PAK2. Activation of PAK2 was essential for apoptosis triggered by CTN. These results collectively demonstrate that CTN stimulates ROS generation and JNK activation for mitochondria-dependent apoptotic signaling in Hep G2 cells, and these apoptotic biochemical events are blocked by pretreatment with resveratrol, which exerts antioxidant effects.
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30
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Delpire E. The mammalian family of sterile 20p-like protein kinases. Pflugers Arch 2009; 458:953-67. [PMID: 19399514 DOI: 10.1007/s00424-009-0674-y] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2009] [Accepted: 04/15/2009] [Indexed: 12/12/2022]
Abstract
Twenty-eight kinases found in mammalian genomes share similarity to the budding yeast kinase Ste20p. This review article examines the biological function of these mammalian Ste20 kinases. Some of them have conserved the Ste20p function of transducing extracellular signals to mitogen-activated kinases. Others affect ion transport, cell cycle, cytoskeleton organization, and program cell death. A number of molecular details involved in the activation of the kinases are discussed including autophosphorylation, substrate recognition, autoinhibition, dimerization, and substrate binding.
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Affiliation(s)
- Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical Center, T-4202 MCN 1161 21st Avenue South, Nashville, TN 37232-2520, USA.
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31
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Zhou L, Yan C, Gieling RG, Kida Y, Garner W, Li W, Han YP. Tumor necrosis factor-alpha induced expression of matrix metalloproteinase-9 through p21-activated kinase-1. BMC Immunol 2009; 10:15. [PMID: 19298660 PMCID: PMC2669056 DOI: 10.1186/1471-2172-10-15] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 03/19/2009] [Indexed: 11/26/2022] Open
Abstract
Background Expressed in embryonic development, matrix metalloprotein-9 (MMP-9) is absent in most of developed adult tissues, but recurs in inflammation during tissue injury, wound healing, tumor formation and metastasis. Expression of MMP-9 is tightly controlled by extracellular cues including pro-inflammatory cytokines and extracellular matrix (ECM). While the pathologic functions of MMP-9 are evident, the intracellular signaling pathways to control its expression are not fully understood. In this study we investigated mechanism of cytokine induced MMP-9 with particular emphasis on the role of p21-activated-kinase-1 (PAK1) and the down stream signaling. Results In response to TNF-alpha or IL-1alpha, PAK1 was promptly activated, as characterized by a sequential phosphorylation, initiated at threonine-212 followed by at threonine-423 in the activation loop of the kinase, in human skin keratinocytes, dermal fibroblasts, and rat hepatic stellate cells. Ectopic expression of PAK1 variants, but not p38 MAP kinase, impaired the TNF-alpha-induced MMP-9 expression, while other MMPs such as MMP-2, -3 and -14 were not affected. Activation of Jun N-terminal kinase (JNK) and NF-kappaB has been demonstrated to be essential for MMP-9 expression. Expression of inactive PAK1 variants impaired JNK but not NF-kappaB activation, which consequently suppressed the 5'-promoter activities of the MMP-9 gene. After the cytokine-induced phosphorylation, both ectopically expressed and endogenous PAK1 proteins were promptly accumulated even in the condition of suppressing protein synthesis, suggesting the PAK1 protein is stabilized upon TNF-alpha stimulation. Stabilization of PAK1 protein by TNF-alpha treatment is independent of the kinase catalytic activity and p21 GTPase binding capacities. In contrast to epithelial cells, mesenchymal cells require 3-dimensional type-I collagen in response to TNF-alpha to massively express MMP-9. The collagen effect is mediated, in part, by boost JNK activation in a way to cooperate the cytokine signaling. Conclusion We identified a novel mechanism for MMP-9 expression in response to injury signals, which is mediated by PAK1 activation and stabilization leading JNK activation.
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Affiliation(s)
- Ling Zhou
- Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
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32
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Wang PS, Chou FS, Porchia L, Saji M, Pinzone JJ. Troglitazone inhibits cell migration, adhesion, and spreading by modulating cytoskeletal rearrangement in human breast cancer cells. Mol Carcinog 2008; 47:905-15. [PMID: 18314876 DOI: 10.1002/mc.20429] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Metastatic tumors are the primary cause of death in patients with breast cancer. Recent data indicate that the peroxisome proliferator-activated receptor gamma (PPARgamma) ligands, thiazolidinediones (TZDs), possess anti-invasive activities on human breast cancer cells. However, the effects of TZDs on other metastatic properties of breast cancer cells such as adhesion, spreading, and migration are not well established. In this study, we show that troglitazone (TG), a member of the TZD family, inhibits lamellipodia formation or membrane ruffling as well as actin polymerization at these structures in MDA-MB-231 and T47D breast cancer cells. In addition, TG reduces migration, adhesion, and spreading on fibronectin (FN)-coated plates. These phenomena were associated with the dramatic decrease of Tyr397 and Tyr576 phosphorylation of focal adhesion kinase (FAK) and the detergent-insoluble Rac1. We also found that TG upregulates Tyr416 phosphorylation of Src, but downregulates the Src-FAK complex. Moreover, we use a PPARgamma-inactive derivative of TG (STG28) and a PPARgamma antagonist (GW9662) to eliminate PPARgamma-mediated effects. We found that treatment with STG28 or GW9662 plus TG showed similar effects compared to TG treatment alone on tyrosine phosphorylation of FAK and Src, indicating that these effects are not the result of PPARgamma activation. Interestingly, we found that TG upregulates actin filament assembly at the point of cell-cell contact in T47D cells, indicating that TG may also upregulate cell-cell adhesion in breast cancer cells which express E-cadherin. These results suggested that TG should be investigated further for its therapeutic potential in metastatic breast cancer.
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Affiliation(s)
- Pei-Shan Wang
- Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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33
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Higashi T, Ikeda T, Shirakawa R, Kondo H, Kawato M, Horiguchi M, Okuda T, Okawa K, Fukai S, Nureki O, Kita T, Horiuchi H. Biochemical characterization of the Rho GTPase-regulated actin assembly by diaphanous-related formins, mDia1 and Daam1, in platelets. J Biol Chem 2008; 283:8746-55. [PMID: 18218625 DOI: 10.1074/jbc.m707839200] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The diaphanous-related formins are actin nucleating and elongating factors. They are kept in an inactive state by an intramolecular interaction between the diaphanous inhibitory domain (DID) and the diaphanous-autoregulatory domain (DAD). It is considered that the dissociation of this autoinhibitory interaction upon binding of GTP-bound Rho to the GTPase binding domain next to DID induces exposure of the FH1-FH2 domains, which assemble actin filaments. Here, we isolated two diaphanous-related formins, mDia1 and Daam1, in platelet extracts by GTP-RhoA affinity column chromatography. We characterized them by a novel assay, where beads coated with the FH1-FH2-DAD domains of either mDia1 or Daam1 were incubated with platelet cytosol, and the assembled actin filaments were observed after staining with rhodamine-phalloidin. Both formins generated fluorescent filamentous structures on the beads. Quantification of the fluorescence intensity of the beads revealed that the initial velocity in the presence of mDia1 was more than 10 times faster than in the presence of Daam1. The actin assembly activities of both FH1-FH2-DADs were inhibited by adding cognate DID domains. GTP-RhoA, -RhoB, and -RhoC, but not GTP-Rac1 or -Cdc42, bound to both mDia1 and Daam1 and efficiently neutralized the inhibition by the DID domains. The association between RhoA and Daam1 was induced by thrombin stimulation in platelets, and RhoA-bound endogenous formins induced actin assembly, which was inhibited by the DID domains of Daam1 and mDia1. Thus, mDia1 and Daam1 are platelet actin assembly factors having distinct efficiencies, and they are directly regulated by Rho GTPases.
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Affiliation(s)
- Tomohito Higashi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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34
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Crystal Structures of the p21-activated kinases PAK4, PAK5, and PAK6 reveal catalytic domain plasticity of active group II PAKs. Structure 2007; 15:201-13. [PMID: 17292838 PMCID: PMC1885963 DOI: 10.1016/j.str.2007.01.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 01/04/2007] [Accepted: 01/07/2007] [Indexed: 11/26/2022]
Abstract
p21-activated kinases have been classified into two groups based on their domain architecture. Group II PAKs (PAK4–6) regulate a wide variety of cellular functions, and PAK deregulation has been linked to tumor development. Structural comparison of five high-resolution structures comprising all active, monophosphorylated group II catalytic domains revealed a surprising degree of domain plasticity, including a number of catalytically productive and nonproductive conformers. Rearrangements of helix αC, a key regulatory element of kinase function, resulted in an additional helical turn at the αC N terminus and a distortion of its C terminus, a movement hitherto unseen in protein kinases. The observed structural changes led to the formation of interactions between conserved residues that structurally link the glycine-rich loop, αC, and the activation segment and firmly anchor αC in an active conformation. Inhibitor screening identified six potent PAK inhibitors from which a tri-substituted purine inhibitor was cocrystallized with PAK4 and PAK5.
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35
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Chan WH, Wu HJ, Shiao NH. Apoptotic signaling in methylglyoxal-treated human osteoblasts involves oxidative stress, c-Jun N-terminal kinase, caspase-3, and p21-activated kinase 2. J Cell Biochem 2007; 100:1056-69. [PMID: 17131386 DOI: 10.1002/jcb.21114] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Methylglyoxal (MG) is a reactive dicarbonyl compound endogenously produced mainly from glycolytic intermediates. MG is cytotoxic through induction of cell death, and elevated MG levels in diabetes patients are believed to contribute to diabetic complications. In this report, we show for the first time that MG treatment triggers apoptosis in human osteoblasts. We further show that MG-induced apoptosis of osteoblasts involves specific apoptotic biochemical changes, including oxidative stress, c-Jun N-terminal kinase (JNK) activation, mitochondrial membrane potential changes, cytochrome C release, increased Bax/Bcl-2 protein ratios, and activation of caspases (caspase-9, caspase-3) and p21-activated protein kinase 2 (PAK2). Treatment of osteoblasts with SP600125, a JNK-specific inhibitor, led to a reduction in MG-induced apoptosis and decreased activation of caspase-3 and PAK2, indicating that JNK activity is upstream of these events. Experiments using anti-sense oligonucleotides against PAK2 further showed that PAK2 activation is required for MG-induced apoptosis in osteoblasts. Interestingly, we also found that MG treatment triggered nuclear translocation of NF-kappaB, although the precise regulatory role of NF-kappaB activation in MG-induced apoptosis remains unclear. Lastly, we examined the effect of MG on osteoblasts in vivo, and found that exposure of rats to dietary water containing 100-200 microM MG caused bone mineral density (BMD) loss. Collectively, these results reveal for the first time that MG treatment triggers apoptosis in osteoblasts via specific apoptotic signaling, and causes BMD loss in vivo.
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Affiliation(s)
- Wen-Hsiung Chan
- Department of Bioscience Technology and Center for Nanotechnology, Chung Yuan Christian University, Chung Li, Taiwan.
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36
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Zhao J, Pei DS, Zhang QG, Zhang GY. Down-regulation Cdc42 attenuates neuronal apoptosis through inhibiting MLK3/JNK3 cascade during ischemic reperfusion in rat hippocampus. Cell Signal 2007; 19:831-43. [PMID: 17161586 DOI: 10.1016/j.cellsig.2006.10.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2006] [Revised: 10/21/2006] [Accepted: 10/22/2006] [Indexed: 01/11/2023]
Abstract
JNK signaling pathway is activated and involved in the selective neuronal death in the hippocampal CA1 subfield following cerebral ischemia. However, little is known about upstream partner controlling the pathway. Here we reported that ischemia/reperfusion significantly elevated Cdc42 activity, enhanced assembly of the Cdc42-MLK3 complex and activation of JNK pathway. Most importantly, knock-down endogenous Cdc42 selectively suppressed the MLK3/MKK7/JNK3 cascade, and subsequently blocked the phosphorylation of c-Jun and FasL expression. Meanwhile, Bcl-2 was inactivated and the release of cytochrome c was diminished. These alterations eventually perturbed the caspase-3 activation as well as post-ischemic neuronal cell death. Taken together, our findings strongly suggest that Cdc42 serves as an upstream activator and modulates JNK-mediated apoptosis machinery in vivo, which ultimately results in neuronal apoptosis via nuclear and non-nuclear pathways. Thus, Cdc42 may be a potential therapeutic target in ischemic brain injury.
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Affiliation(s)
- Jie Zhao
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical College, Xuzhou, China
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37
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Tsai IC, Hsieh YJ, Lyu PC, Yu JS. Anti-phosphopeptide antibody, P-STM as a novel tool for detecting mitotic phosphoproteins: identification of lamins A and C as two major targets. J Cell Biochem 2005; 94:967-81. [PMID: 15597429 DOI: 10.1002/jcb.20353] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A polyclonal, phospho-epitope-specific antibody (P-STM) was generated to detect the activated p21-activated kinase 2 (PAK2), based on the regulatory autophosphorylation site Thr(402) of PAK2 [Yu et al., 1998]. In this report, we show that this antibody can also recognize many phosphoproteins in mitotic HeLa and A431 cells. Signal of these phosphoproteins emerged after treating the cells with nocodazole and okadaic acid, and was highly detected in G2-M phase transition of HeLa cells released from double thymidine block. Immunofluorescence analysis revealed that P-STM strongly stained HeLa cells at prometaphase and metaphase, but not at interphase and anaphase. Interestingly, this staining pattern was almost identical to that obtained by staining with MPM2, a monoclonal antibody known to react with phosphoproteins in mitotic HeLa cells. However, the phosphoproteins detected by the two antibodies are quite different. Two-dimensional gel electrophoresis (2DE) and tryptic peptide fingerprint analysis by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry were employed to identify lamins A and C as two of the mitotic cell-specific phosphoproteins recognized by P-STM. Lamins A and C immunoprecipitated from nocodazole-treated cells, but not from untreated cells showed strong reactivity to P-STM, and this reactivity lost completely after protein phosphatase 2A treatment. In summary, our results show that P-STM represents a novel tool for detecting mitotic phosphoproteins, which are different from those recognized by MPM2, and that lamins A and C are the two prominent mitotic phosphoproteins detected by P-STM.
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Affiliation(s)
- I-Chen Tsai
- Department of Cell and Molecular Biology, Graduate Institute of Basic Medical Sciences, Medical College of Chang Gung University, Tao-Yuan, Taiwan, Republic of China
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38
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Lee J, Jung ID, Chang WK, Park CG, Cho DY, Shin EY, Seo DW, Kim YK, Lee HW, Han JW, Lee HY. p85 beta-PIX is required for cell motility through phosphorylations of focal adhesion kinase and p38 MAP kinase. Exp Cell Res 2005; 307:315-28. [PMID: 15893751 DOI: 10.1016/j.yexcr.2005.03.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Revised: 02/22/2005] [Accepted: 03/01/2005] [Indexed: 11/25/2022]
Abstract
Lysophosphatidic acid (LPA) mediates diverse biological responses, including cell migration, through the activation of G-protein-coupled receptors. Recently, we have shown that LPA stimulates p21-activated kinase (PAK) that is critical for focal adhesion kinase (FAK) phosphorylation and cell motility. Here, we provide the direct evidence that p85 beta-PIX is required for cell motility of NIH-3T3 cells by LPA through FAK and p38 MAP kinase phosphorylations. LPA induced p85 beta-PIX binding to FAK in NIH-3T3 cells that was inhibited by pretreatment of the cells with phosphoinositide 3-kinase inhibitor, LY294002. Furthermore, the similar inhibition of the complex formation was also observed, when the cells were transfected with either p85 beta-PIX mutant that cannot bind GIT or dominant negative mutants of Rac1 (N17Rac1) and PAK (PAK-PID). Transfection of the cells with specific p85 beta-PIX siRNA led to drastic inhibition of LPA-induced FAK phosphorylation, peripheral redistribution of p85 beta-PIX with FAK and GIT1, and cell motility. p85 beta-PIX was also required for p38 MAP kinase phosphorylation induced by LPA. Finally, dominant negative mutant of Rho (N19Rho)-transfected cells did not affect PAK activation, while the cells stably transfected with p85 beta-PIX siRNA or N17Rac1 showed the reduction of LPA-induced PAK activation. Taken together, the present data suggest that p85 beta-PIX, located downstream of Rac1, is a key regulator for the activations of FAK or p38 MAP kinase and plays a pivotal role in focal complex formation and cell motility induced by LPA.
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Affiliation(s)
- Jangsoon Lee
- Department of Pharmacology, College of Medicine, Konyang University, Nonsan, 320-711, Republic of Korea
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39
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Lei M, Robinson MA, Harrison SC. The active conformation of the PAK1 kinase domain. Structure 2005; 13:769-78. [PMID: 15893667 DOI: 10.1016/j.str.2005.03.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 03/13/2005] [Accepted: 03/14/2005] [Indexed: 11/24/2022]
Abstract
The p21-activated kinases (PAKs) participate in cytoskeletal control networks, downstream of Rho-family GTPases. A structure of PAK1 in an autoregulated, "off" state showed that a regulatory region, N-terminal to the kinase domain, forces the latter into an inactive conformation, prevents phosphorylation of Thr423 in the activation loop, and promotes dimerization. We have now determined structures at 1.8 A resolution for the free PAK1 kinase domain, with a mutation in the active site that blocks enzymatic activity, and for the same domain with a "phosphomimetic" mutation in the activation loop. The two very similar structures show that even in the absence of a phosphorylated Thr423, the kinase has an essentially active conformation. When Cdc42 binds the regulatory region and dissociates the dimer, PAK1 will be in an "intermediate-active" state, with a capacity to phosphorylate itself or other substrates even prior to modification of its activation loop.
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Affiliation(s)
- Ming Lei
- Laboratory of Molecular Medicine, Children's Hospital, 320 Longwood Avenue, Boston, Massachusetts 02115, USA
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40
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Abstract
The family members of the mitogen-activated protein (MAP) kinases mediate a wide variety of cellular behaviors in response to extracellular stimuli. One of the four main sub-groups, the p38 group of MAP kinases, serve as a nexus for signal transduction and play a vital role in numerous biological processes. In this review, we highlight the known characteristics and components of the p38 pathway along with the mechanism and consequences of p38 activation. We focus on the role of p38 as a signal transduction mediator and examine the evidence linking p38 to inflammation, cell cycle, cell death, development, cell differentiation, senescence and tumorigenesis in specific cell types. Upstream and downstream components of p38 are described and questions remaining to be answered are posed. Finally, we propose several directions for future research on p38.
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Affiliation(s)
- Tyler Zarubin
- Department of Immunology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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41
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Keniry ME, Kemp HA, Rivers DM, Sprague GF. The identification of Pcl1-interacting proteins that genetically interact with Cla4 may indicate a link between G1 progression and mitotic exit. Genetics 2004; 166:1177-86. [PMID: 15082539 PMCID: PMC1470798 DOI: 10.1534/genetics.166.3.1177] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In budding yeast, Cla4 and Ste20, two p21-activated kinases, contribute to numerous morphogenetic processes. Loss of Ste20 or Cla4 individually confers distinct phenotypes, implying that they regulate different processes. However, loss of both proteins is lethal, suggesting some functional overlap. To explore the role(s) of Cla4, we and others have sought mutations that are lethal in a cla4 Delta strain. These mutations define >60 genes. Recently, both Ste20 and Cla4 have been implicated in mitotic exit. Here, we identify a genetic interaction between PHO85, which encodes a cyclin-dependent kinase, and CLA4. We further show that the Pho85-coupled G(1) cyclins Pcl1 and Pcl2 contribute to this Pho85 role. We performed a two-hybrid screen with Pcl1. Three Pcl1-interacting proteins were identified: Ncp1, Hms1, and a novel ATPase dubbed Epa1. Each of these proteins interacts with Pcl1 in GST pull-down experiments and is specifically phosphorylated by Pcl1.Pho85 complexes. NCP1, HMS1, and EPA1 also genetically interact with CLA4. Like Cla4, the proteins Hms1, Ncp1, and Pho85 appear to affect mitotic exit, a conclusion that follows from the mislocalization of Cdc14, a key mitotic regulator, in strains lacking these proteins. We propose a model in which the G(1) Pcl1.Pho85 complex regulates mitotic exit machinery.
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Affiliation(s)
- Megan E Keniry
- Department of Biology and Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229, USA
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42
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Menard RE, Mattingly RR. Cell surface receptors activate p21-activated kinase 1 via multiple Ras and PI3-kinase-dependent pathways. Cell Signal 2004; 15:1099-109. [PMID: 14575865 DOI: 10.1016/s0898-6568(03)00087-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
p21-activated kinases (PAKs) were the first identified mammalian members of a growing family of Ste20-like serine-threonine protein kinases. In this study, we show that PAK1 can be stimulated by carbachol, lysophosphatidic acid (LPA), epidermal growth factor (EGF), and phorbol 12-myristate 13-acetate (PMA) by multiple independent and overlapping pathways. Dominant-negative Ras, Rac, and Cdc42 inhibited PAK1 activation by all of these agonists, while active Rac1 and Cdc42 were sufficient to maximally activate PAK1 in the absence of any treatment. Active Ras induced only a weak activation of PAK1 that could be potentiated by muscarinic receptor stimulation. Studies using inhibitors of the EGF receptor tyrosine kinase, phosphatidylinositol 3-kinase (PI3-kinase) and protein kinase C (PKC) revealed that all of the cell surface agonists could activate PAK1 through pathways independent of PKC, that EGF stimulated a PI3-kinase dependent pathway to stimulate PAK1, and that muscarinic receptor stimulation of PAK1 was predominantly mediated through this EGF-R-dependent mechanism. Activation of PAK1 by LPA was independent of PI3-kinase and the EGF receptor, but was inhibited by dominant-negative RhoA. These results identify multiple Ras-dependent pathways to activation of PAK1.
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Affiliation(s)
- Raymond E Menard
- Department of Pharmacology, Wayne State University, 540 E. Canfield, Room 6326, Detroit, MI 48201, USA
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Abstract
Growth and differentiation of the budding yeast Saccharomyces cerevisiae is regulated by six functionally distinct but structurally similar MAP kinase cascades. Three of the protein kinases in the cascade that regulates G1-phase arrest and mating have recently been shown to form a multikinase complex with a LIM-domain-containing protein called Ste5. These studies implicate Ste5 as a tethering protein that physically links protein kinases operating sequentially in a cascade. The significance of this complex for the regulation and specificity of signal transduction is explored in this review.
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Affiliation(s)
- E A Elion
- Dept of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
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Abstract
The p21-activated kinases (PAKs) 1-3 are serine/threonine protein kinases whose activity is stimulated by the binding of active Rac and Cdc42 GTPases. Our understanding of the regulation and biology of these important signaling proteins has increased tremendously since their discovery in the mid-1990s. PAKs 1-3 are activated by a variety of GTPase-dependent and -independent mechanisms. This complexity reflects the contributions of PAK function in many cellular signaling pathways and the need to carefully control PAK action in a highly localized manner. PAKs serve as important regulators of cytoskeletal dynamics and cell motility, transcription through MAP kinase cascades, death and survival signaling, and cell-cycle progression. Consequently, PAKs have also been implicated in a number of pathological conditions and in cell transformation. We propose here a key role for PAK action in coordinating the dynamics of the actin and microtubule cytoskeletons during directional motility of cells, as well as in other functions requiring cytoskeletal polarization.
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Affiliation(s)
- Gary M Bokoch
- Departments of Immunology and Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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Gnesutta N, Minden A. Death receptor-induced activation of initiator caspase 8 is antagonized by serine/threonine kinase PAK4. Mol Cell Biol 2003; 23:7838-48. [PMID: 14560027 PMCID: PMC207651 DOI: 10.1128/mcb.23.21.7838-7848.2003] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2002] [Revised: 03/12/2003] [Accepted: 07/30/2003] [Indexed: 12/11/2022] Open
Abstract
Normal cell growth requires a precisely controlled balance between cell death and survival. This involves activation of different types of intracellular signaling cascades within the cell. While some types of signaling proteins regulate apoptosis, or programmed cell death, other proteins within the cell can promote survival. The serine/threonine kinase PAK4 can protect cells from apoptosis in response to several different types of stimuli. As is the case for other members of the p21-activated kinase (PAK) family, one way that PAK4 may promote cell survival is by phosphorylating and thereby inhibiting the proapoptotic protein Bad. This leads in turn to the inhibition of effector caspases such as caspase 3. Here we show that in response to cytokines which activate death domain-containing receptors, such as the tumor necrosis factor and Fas receptors, PAK4 can inhibit the death signal by a different mechanism. Under these conditions, PAK4 inhibits apoptosis early in the caspase cascade, antagonizing the activation of initiator caspase 8. This inhibition, which does not require PAK4's kinase activity, may involve inhibition of caspase 8 recruitment to the death domain receptors. This role in regulating initiator caspases is an entirely novel role for the PAK proteins and suggests a new mechanism by which these proteins promote cell survival.
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Affiliation(s)
- Nerina Gnesutta
- Biological Sciences, Columbia University, New York, New York 10027, USA
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Abstract
The p21-activated kinases (PAKs) play an important role in diverse cellular processes. PAK2 is activated by autophosphorylation upon binding of small G proteins such as Cdc42 and Rac in the GTP-bound state. However, the mechanism of PAK2 autophosphorylation in vitro is unclear. In the present study, the kinetic theory of the substrate reaction during modification of enzyme activity has been applied to a study of the autoactivation of PAK2. On the basis of the kinetic equation of the substrate reaction during the autophosphorylation of PAK2, the activation rate constants for the free enzyme and enzyme-substrate complex have been determined. The results indicate that 1) in the presence of Cdc42, PAK2 autophosphorylation is a bipartite mechanism, with the regulatory domain autophosphorylated at multiple residues, whereas activation coincides with autophosphorylation of the catalytic domain at Thr-402; 2) the autophosphorylation reactions in regulatory domain are either a nonlimiting step or not required for activation of enzyme; 3) the autophosphorylation at site Thr-402 on the catalytic domain occurs by an intermolecular mechanism and is required for phosphorylation of exogenous substrates examined; 4) binding of the exogenous protein/peptide substrates at the active site of PAK2 has little or no effect on the autoactivation of PAK2, suggesting that multiple regions of PAK2 are involved in the enzyme-substrate recognition. The present method also provides a novel approach for studying autophosphorylation reactions. Since the experimental conditions used resemble more closely the in vivo situation where the substrate is constantly being turned over while the enzyme is being modified, this new method would be particularly useful when the regulatory mechanisms of the reversible phosphorylation reaction toward certain enzymes are being assessed.
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Affiliation(s)
- Hao Wu
- National Laboratory of Biomacromolecules, Center for Molecular Biology, Institute of Biophysics, Academia Sinica, Beijing 100101, China
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Jakobi R, McCarthy CC, Koeppel MA, Stringer DK. Caspase-activated PAK-2 is regulated by subcellular targeting and proteasomal degradation. J Biol Chem 2003; 278:38675-85. [PMID: 12853446 DOI: 10.1074/jbc.m306494200] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p21-activated protein kinases (PAKs) are a family of serine/threonine protein kinases that are activated by binding of the p21 G proteins Cdc42 or Rac. The ubiquitous PAK-2 (gamma-PAK) is unique among the PAK isoforms because it is also activated through proteolytic cleavage by caspases or caspase-like proteases. In response to stress stimulants such as tumor necrosis factor alpha or growth factor withdrawal, PAK-2 is activated as a full-length enzyme and as a proteolytic PAK-2p34 fragment. Activation of full-length PAK-2 stimulates cell survival, whereas proteolytic activation of PAK-2p34 is involved in programmed cell death. Here we provide evidence that the proapoptotic effect of PAK-2p34 is regulated by subcellular targeting and degradation by the proteasome. Full-length PAK-2 is localized in the cytoplasm, whereas the proteolytic PAK-2p34 fragment translocates to the nucleus. Subcellular localization of PAK-2 is regulated by nuclear localization and nuclear export signal motifs. A nuclear export signal motif within the regulatory domain prevents nuclear localization of full-length PAK-2. Proteolytic activation removes most of the regulatory domain and disrupts the nuclear export signal. The activated PAK-2p34 fragment contains a nuclear localization signal and translocates to the nucleus. However, levels of activated PAK-2p34 are tightly regulated through ubiquitination and degradation by the proteasome. Inhibition of degradation by blocking polyubiquitination results in significantly increased levels of PAK-2p34 and as a consequence, in stimulation of programmed cell death. Therefore, nuclear targeting and inhibition of degradation appear to be critical for stimulation of the cell death response by PAK-2p34.
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Affiliation(s)
- Rolf Jakobi
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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Chou MM, Masuda-Robens JM, Gupta ML. Cdc42 promotes G1 progression through p70 S6 kinase-mediated induction of cyclin E expression. J Biol Chem 2003; 278:35241-7. [PMID: 12842876 DOI: 10.1074/jbc.m305246200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The Rho family GTPase Cdc42 is recognized for its role in cellular proliferation and transformation. However, the mechanism by which it promotes cell cycle progression has remained undefined. Using an inducible expression system, we show that constitutively active Cdc42 (Cdc42V12) is sufficient by itself to induce anchorage-independent but not mitogen-independent growth in NIH3T3 cells. However, Cdc42V12 markedly accelerates activation of cyclin E-Cdk2 in response to mitogen. These effects were highly specific, as the kinetics of cyclin D-Cdk4 activation was unaltered. Cdc42V12 promotes Cdk2 activation by selectively inducing cyclin E expression without affecting other regulatory proteins such as the p27 Cdk inhibitor or Cdc25A. Furthermore, Cdc42V12 was able to activate a reporter gene driven by the cyclin E promoter in the absence of exogenous mitogen or adhesion. Cyclin E induction was sensitive to rapamycin but not inhibitors of mitogen-activated protein kinases, implicating p70 S6 kinase (p70S6k) as the relevant mediator. Consistent with this notion, wild type and constitutively active alleles of p70S6k were sufficient to activate the cyclin E promoter. In sum, these studies provide novel insights into the mechanism by which Cdc42 promotes G1 progression.
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Affiliation(s)
- Margaret M Chou
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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Flanders JA, Feng Q, Bagrodia S, Laux MT, Singavarapu A, Cerione RA. The Cbl proteins are binding partners for the Cool/Pix family of p21-activated kinase-binding proteins. FEBS Lett 2003; 550:119-23. [PMID: 12935897 DOI: 10.1016/s0014-5793(03)00853-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Members of the Cool protein family contain SH3, Dbl, and pleckstrin homology domains and are binding partners for the p21-activated kinase (PAK). Using the yeast two-hybrid screen, we identified Cbl-b as a Cool family binding partner. We co-immunoprecipitated endogenous Cool and Cbl-b from a variety of breast cancer cell lines. The Cool-Cbl-b interaction requires the SH3 domain of Cool and competes with the binding of PAK to Cool proteins. Expression of Cbl-b effectively blocks the ability of Cool-2 to stimulate PAK, thus providing an additional mechanism, aside from catalyzing receptor ubiquitination, by which Cbl-b acts as a negative regulator for signaling activities requiring PAK activation.
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Affiliation(s)
- James A Flanders
- Department of Molecular Medicine, Baker Laboratory, Cornell University, Veterinary Medical Center, Ithaca, NY 14853, USA
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50
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McPhie DL, Coopersmith R, Hines-Peralta A, Chen Y, Ivins KJ, Manly SP, Kozlowski MR, Neve KA, Neve RL. DNA synthesis and neuronal apoptosis caused by familial Alzheimer disease mutants of the amyloid precursor protein are mediated by the p21 activated kinase PAK3. J Neurosci 2003; 23:6914-27. [PMID: 12890786 PMCID: PMC6740729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023] Open
Abstract
Apoptotic pathways and DNA synthesis are activated in neurons in the brains of individuals with Alzheimer disease (AD). However, the signaling mechanisms that mediate these events have not been defined. We show that expression of familial AD (FAD) mutants of the amyloid precursor protein (APP) in primary neurons in culture causes apoptosis and DNA synthesis. Both the apoptosis and the DNA synthesis are mediated by the p21 activated kinase PAK3, a serine-threonine kinase that interacts with APP. A dominant-negative kinase mutant of PAK3 inhibits the neuronal apoptosis and DNA synthesis; this effect is abolished by deletion of the PAK3 APP-binding domain or by coexpression of a peptide representing this binding domain. The involvement of PAK3 specifically in FAD APP-mediated apoptosis rather than in general apoptotic pathways is suggested by the facts that a dominant-positive mutant of PAK3 does not alone cause neuronal apoptosis and that the dominant-negative mutant of PAK3 does not inhibit chemically induced apoptosis. Pertussis toxin, which inactivates the heterotrimeric G-proteins Go and Gi, inhibits the apoptosis and DNA synthesis caused by FAD APP mutants; the apoptosis and DNA synthesis are rescued by coexpression of a pertussis toxin-insensitive Go. FAD APP-mediated DNA synthesis precedes FAD APP-mediated apoptosis in neurons, and inhibition of neuronal entry into the cell cycle inhibits the apoptosis. These data suggest that a normal signaling pathway mediated by the interaction of APP, PAK3, and Go is constitutively activated in neurons by FAD mutations in APP and that this activation causes cell cycle entry and consequent apoptosis.
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Affiliation(s)
- Donna L McPhie
- Department of Psychiatry, Harvard Medical School and McLean Hospital, Belmont, Massachusetts 02478, USA.
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