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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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Zhang W, Bhetwal BP, Gunst SJ. Rho kinase collaborates with p21-activated kinase to regulate actin polymerization and contraction in airway smooth muscle. J Physiol 2018; 596:3617-3635. [PMID: 29746010 DOI: 10.1113/jp275751] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 05/04/2018] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS The mechanisms by which Rho kinase (ROCK) regulates airway smooth muscle contraction were determined in tracheal smooth muscle tissues. ROCK may mediate smooth muscle contraction by inhibiting myosin regulatory light chain (RLC) phosphatase. ROCK can also regulate F-actin dynamics during cell migration, and actin polymerization is critical for airway smooth muscle contraction. Our results show that ROCK does not regulate airway smooth muscle contraction by inhibiting myosin RLC phosphatase or by stimulating myosin RLC phosphorylation. We find that ROCK regulates airway smooth muscle contraction by activating the serine-threonine kinase Pak, which mediates the activation of Cdc42 and neuronal Wiskott-Aldrich syndrome protein (N-WASp). N-WASP transmits signals from Cdc42 to the Arp2/3 complex for the nucleation of actin filaments. These results demonstrate a novel molecular function for ROCK in the regulation of Pak and Cdc42 activation that is critical for the processes of actin polymerization and contractility in airway smooth muscle. ABSTRACT Rho kinase (ROCK), a RhoA GTPase effector, can regulate the contraction of airway and other smooth muscle tissues. In some tissues, ROCK can inhibit myosin regulatory light chain (RLC) phosphatase, which increases the phosphorylation of myosin RLC and promotes smooth muscle contraction. ROCK can also regulate cell motility and migration by affecting F-actin dynamics. Actin polymerization is stimulated by contractile agonists in airway smooth muscle tissues and is required for contractile tension development in addition to myosin RLC phosphorylation. We investigated the mechanisms by which ROCK regulates the contractility of tracheal smooth muscle tissues by expressing a kinase-inactive mutant of ROCK, ROCK-K121G, in the tissues or by treating them with the ROCK inhibitor H-1152P. Our results show no role for ROCK in the regulation of non-muscle or smooth muscle myosin RLC phosphorylation during contractile stimulation in this tissue. We found that ROCK regulates airway smooth muscle contraction by mediating activation of p21-activated kinase (Pak), a serine-threonine kinase, to promote actin polymerization. Pak catalyses paxillin phosphorylation on Ser273 and coupling of the GIT1-βPIX-Pak signalling module to paxillin, which activates the guanine nucleotide exchange factor (GEF) activity of βPIX towards Cdc42. Cdc42 is required for the activation of neuronal Wiskott-Aldrich syndrome protein (N-WASp), which transmits signals from Cdc42 to the Arp2/3 complex for the nucleation of actin filaments. Our results demonstrate a novel molecular function for ROCK in the regulation of Pak and Cdc42 activation that is critical for the processes of actin polymerization and contractility in airway smooth muscle.
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Affiliation(s)
- Wenwu Zhang
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Bhupal P Bhetwal
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Susan J Gunst
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
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Hsiao YC, Chi LM, Chien KY, Chiang WF, Chen SF, Chuang YN, Lin SY, Wu CC, Chang YT, Chu LJ, Chen YT, Chia SL, Chien CY, Chang KP, Chang YS, Yu JS. Development of a Multiplexed Assay for Oral Cancer Candidate Biomarkers Using Peptide Immunoaffinity Enrichment and Targeted Mass Spectrometry. Mol Cell Proteomics 2017; 16:1829-1849. [PMID: 28821604 DOI: 10.1074/mcp.ra117.000147] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Indexed: 01/15/2023] Open
Abstract
Oral cancer is one of the most common cancers worldwide, and there are currently no biomarkers approved for aiding its management. Although many potential oral cancer biomarkers have been discovered, very few have been verified in body fluid specimens in parallel to evaluate their clinical utility. The lack of appropriate multiplexed assays for chosen targets represents one of the bottlenecks to achieving this goal. In the present study, we develop a peptide immunoaffinity enrichment-coupled multiple reaction monitoring-mass spectrometry (SISCAPA-MRM) assay for verifying multiple reported oral cancer biomarkers in saliva. We successfully produced 363 clones of mouse anti-peptide monoclonal antibodies (mAbs) against 36 of 49 selected targets, and characterized useful mAbs against 24 targets in terms of their binding affinity for peptide antigens and immuno-capture ability. Comparative analyses revealed that an equilibrium dissociation constant (KD ) cut-off value < 2.82 × 10-9 m could identify most clones with an immuno-capture recovery rate >5%. Using these mAbs, we assembled a 24-plex SISCAPA-MRM assay and optimized assay conditions in a 25-μg saliva matrix background. This multiplexed assay showed reasonable precision (median coefficient of variation, 7.16 to 32.09%), with lower limits of quantitation (LLOQ) of <10, 10-50, and >50 ng/ml for 14, 7 and 3 targets, respectively. When applied to a model saliva sample pooled from oral cancer patients, this assay could detect 19 targets at higher salivary levels than their LLOQs. Finally, we demonstrated the utility of this assay for quantification of multiple targets in individual saliva samples (20 healthy donors and 21 oral cancer patients), showing that levels of six targets were significantly altered in cancer compared with the control group. We propose that this assay could be used in future studies to compare the clinical utility of multiple oral cancer biomarker candidates in a large cohort of saliva samples.
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Affiliation(s)
- Yung-Chin Hsiao
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan.,§Liver Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Lang-Ming Chi
- ¶Clinical Proteomics Core Laboratory, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Kun-Yi Chien
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan.,¶Clinical Proteomics Core Laboratory, Chang Gung Memorial Hospital, Taoyuan, Taiwan.,‖Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Wei-Fan Chiang
- **Department of Oral & Maxillofacial Surgery, Chi-Mei Medical Center, Liouying, Taiwan.,‡‡School of Dentistry, National Yang Ming University, Taipei, Taiwan
| | - Szu-Fan Chen
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Yao-Ning Chuang
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Shih-Yu Lin
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Chia-Chun Wu
- ‖Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Ya-Ting Chang
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Lichieh Julie Chu
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan.,§Liver Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Yi-Ting Chen
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan.,‖Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,§§Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,¶¶Department of Nephrology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
| | - Shu-Li Chia
- ‖‖Health Promotion Administration, Ministry of Health and Welfare, Taiwan
| | - Chih-Yen Chien
- Department of Otolaryngology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Kai-Ping Chang
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan.,Departments of Otolaryngology-Head & Neck Surgery, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Yu-Sun Chang
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan.,Departments of Otolaryngology-Head & Neck Surgery, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Jau-Song Yu
- From the ‡Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan; .,§Liver Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan.,‖Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
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Lin YT, Chien KY, Wu CC, Chang WY, Chu LJ, Chen MC, Yeh CT, Yu JS. Super-SILAC mix coupled with SIM/AIMS assays for targeted verification of phosphopeptides discovered in a large-scale phosphoproteome analysis of hepatocellular carcinoma. J Proteomics 2017; 157:40-51. [DOI: 10.1016/j.jprot.2017.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 01/23/2017] [Accepted: 02/08/2017] [Indexed: 01/04/2023]
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Zhang W, Huang Y, Gunst SJ. p21-Activated kinase (Pak) regulates airway smooth muscle contraction by regulating paxillin complexes that mediate actin polymerization. J Physiol 2016; 594:4879-900. [PMID: 27038336 DOI: 10.1113/jp272132] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 03/28/2016] [Indexed: 01/01/2023] Open
Abstract
KEY POINTS In airway smooth muscle, tension development caused by a contractile stimulus requires phosphorylation of the 20 kDa myosin light chain (MLC), which activates crossbridge cycling and the polymerization of a pool of submembraneous actin. The p21-activated kinases (Paks) can regulate the contractility of smooth muscle and non-muscle cells, and there is evidence that this occurs through the regulation of MLC phosphorylation. We show that Pak has no effect on MLC phosphorylation during the contraction of airway smooth muscle, and that it regulates contraction by mediating actin polymerization. We find that Pak phosphorylates the adhesion junction protein, paxillin, on Ser273, which promotes the formation of a signalling complex that activates the small GTPase, cdc42, and the actin polymerization catalyst, neuronal Wiskott-Aldrich syndrome protein (N-WASP). These studies demonstrate a novel role for Pak in regulating the contractility of smooth muscle by regulating actin polymerization. ABSTRACT The p21-activated kinases (Pak) can regulate contractility in smooth muscle and other cell and tissue types, but the mechanisms by which Paks regulate cell contractility are unclear. In airway smooth muscle, stimulus-induced contraction requires phosphorylation of the 20 kDa light chain of myosin, which activates crossbridge cycling, as well as the polymerization of a small pool of actin. The role of Pak in airway smooth muscle contraction was evaluated by inhibiting acetylcholine (ACh)-induced Pak activation through the expression of a kinase inactive mutant, Pak1 K299R, or by treating tissues with the Pak inhibitor, IPA3. Pak inhibition suppressed actin polymerization and contraction in response to ACh, but it did not affect myosin light chain phosphorylation. Pak activation induced paxillin phosphorylation on Ser273; the paxillin mutant, paxillin S273A, inhibited paxillin Ser273 phosphorylation and inhibited actin polymerization and contraction. Immunoprecipitation analysis of tissue extracts and proximity ligation assays in dissociated cells showed that Pak activation and paxillin Ser273 phosphorylation triggered the formation of an adhesion junction signalling complex with paxillin that included G-protein-coupled receptor kinase-interacting protein (GIT1) and the cdc42 guanine exchange factor, βPIX (Pak interactive exchange factor). Assembly of the Pak-GIT1-βPIX-paxillin complex was necessary for cdc42 and neuronal Wiskott-Aldrich syndrome protein (N-WASP) activation, actin polymerization and contraction in response to ACh. RhoA activation was also required for the recruitment of Pak to adhesion junctions, Pak activation, paxillin Ser273 phosphorylation and paxillin complex assembly. These studies demonstrate a novel role for Pak in the regulation of N-WASP activation, actin dynamics and cell contractility.
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Affiliation(s)
- Wenwu Zhang
- Department of Cellular and Integrative Physiology, Indiana University School Medicine, Indianapolis, IN, 46202-5120, USA
| | - Youliang Huang
- Department of Cellular and Integrative Physiology, Indiana University School Medicine, Indianapolis, IN, 46202-5120, USA
| | - Susan J Gunst
- Department of Cellular and Integrative Physiology, Indiana University School Medicine, Indianapolis, IN, 46202-5120, USA
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P21-Activated Kinase Inhibitors FRAX486 and IPA3: Inhibition of Prostate Stromal Cell Growth and Effects on Smooth Muscle Contraction in the Human Prostate. PLoS One 2016; 11:e0153312. [PMID: 27071060 PMCID: PMC4829229 DOI: 10.1371/journal.pone.0153312] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 03/28/2016] [Indexed: 12/25/2022] Open
Abstract
Prostate smooth muscle tone and hyperplastic growth are involved in the pathophysiology and treatment of male lower urinary tract symptoms (LUTS). Available drugs are characterized by limited efficacy. Patients' adherence is particularly low to combination therapies of 5α-reductase inhibitors and α1-adrenoceptor antagonists, which are supposed to target contraction and growth simultaneously. Consequently, molecular etiology of benign prostatic hyperplasia (BPH) and new compounds interfering with smooth muscle contraction or growth in the prostate are of high interest. Here, we studied effects of p21-activated kinase (PAK) inhibitors (FRAX486, IPA3) in hyperplastic human prostate tissues, and in stromal cells (WPMY-1). In hyperplastic prostate tissues, PAK1, -2, -4, and -6 may be constitutively expressed in catecholaminergic neurons, while PAK1 was detected in smooth muscle and WPMY-1 cells. Neurogenic contractions of prostate strips by electric field stimulation were significantly inhibited by high concentrations of FRAX486 (30 μM) or IPA3 (300 μM), while noradrenaline- and phenylephrine-induced contractions were not affected. FRAX486 (30 μM) inhibited endothelin-1- and -2-induced contractions. In WPMY-1 cells, FRAX486 or IPA3 (24 h) induced concentration-dependent (1-10 μM) degeneration of actin filaments. This was paralleled by attenuation of proliferation rate, being observed from 1 to 10 μM FRAX486 or IPA3. Cytotoxicity of FRAX486 and IPA3 in WPMY-1 cells was time- and concentration-dependent. Stimulation of WPMY-1 cells with endothelin-1 or dihydrotestosterone, but not noradrenaline induced PAK phosphorylation, indicating PAK activation by endothelin-1. Thus, PAK inhibitors may inhibit neurogenic and endothelin-induced smooth muscle contractions in the hyperplastic human prostate, and growth of stromal cells. Targeting prostate smooth muscle contraction and stromal growth at once by a single compound is principally possible, at least under experimental conditions.
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An in cellulo-derived structure of PAK4 in complex with its inhibitor Inka1. Nat Commun 2015; 6:8681. [PMID: 26607847 PMCID: PMC4674680 DOI: 10.1038/ncomms9681] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 09/21/2015] [Indexed: 01/09/2023] Open
Abstract
PAK4 is a metazoan-specific kinase acting downstream of Cdc42. Here we describe the structure of human PAK4 in complex with Inka1, a potent endogenous kinase inhibitor. Using single mammalian cells containing crystals 50 μm in length, we have determined the in cellulo crystal structure at 2.95 Å resolution, which reveals the details of how the PAK4 catalytic domain binds cellular ATP and the Inka1 inhibitor. The crystal lattice consists only of PAK4–PAK4 contacts, which form a hexagonal array with channels of 80 Å in diameter that run the length of the crystal. The crystal accommodates a variety of other proteins when fused to the kinase inhibitor. Inka1–GFP was used to monitor the process crystal formation in living cells. Similar derivatives of Inka1 will allow us to study the effects of PAK4 inhibition in cells and model organisms, to allow better validation of therapeutic agents targeting PAK4. PAK4 is a metazoan-specific kinase, which acts downstream of the cell polarity regulator Cdc42. Here, Baskaran et al. determine the structure of PAK4 bound to the endogenous inhibitor Inka1 from crystals that form spontaneously in mammalian cells overexpressing both proteins.
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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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Abstract
Shank3, which encodes a scaffolding protein at glutamatergic synapses, is a genetic risk factor for autism. In this study, we examined the impact of Shank3 deficiency on the NMDA-type glutamate receptor, a key player in cognition and mental illnesses. We found that knockdown of Shank3 with a small interfering RNA (siRNA) caused a significant reduction of NMDAR-mediated ionic or synaptic current, as well as the surface expression of NR1 subunits, in rat cortical cultures. The effect of Shank3 siRNA on NMDAR currents was blocked by an actin stabilizer, and was occluded by an actin destabilizer, suggesting the involvement of actin cytoskeleton. Since actin dynamics is regulated by the GTPase Rac1 and downstream effector p21-activated kinase (PAK), we further examined Shank3 regulation of NMDARs when Rac1 or PAK was manipulated. We found that the reducing effect of Shank3 siRNA on NMDAR currents was mimicked and occluded by specific inhibitors for Rac1 or PAK, and was blocked by constitutively active Rac1 or PAK. Immunocytochemical data showed a strong reduction of F-actin clusters after Shank3 knockdown, which was occluded by a PAK inhibitor. Inhibiting cofilin, the primary downstream target of PAK and a major actin depolymerizing factor, prevented Shank3 siRNA from reducing NMDAR currents and F-actin clusters. Together, these results suggest that Shank3 deficiency induces NMDAR hypofunction by interfering with the Rac1/PAK/cofilin/actin signaling, leading to the loss of NMDAR membrane delivery or stability. It provides a potential mechanism for the role of Shank3 in cognitive deficit in autism.
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Chen JT, Ho CW, Chi LM, Chien KY, Hsieh YJ, Lin SJ, Yu JS. Identification of the lamin A/C phosphoepitope recognized by the antibody P-STM in mitotic HeLa S3 cells. BMC BIOCHEMISTRY 2013; 14:18. [PMID: 23870088 PMCID: PMC3727946 DOI: 10.1186/1471-2091-14-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 07/16/2013] [Indexed: 01/24/2023]
Abstract
Background Lamins A and C, two major structural components of the nuclear lamina that determine nuclear shape and size, are phosphoproteins. Phosphorylation of lamin A/C is cell cycle-dependent and is involved in regulating the assembly–disassembly of lamin filaments during mitosis. We previously reported that P-STM, a phosphoepitope-specific antibody raised against the autophosphorylation site of p21-activated kinase 2, recognizes a number of phosphoproteins, including lamins A and C, in mitotic HeLa cells. Results Here, using recombinant proteins and synthetic phosphopeptides containing potential lamin A/C phosphorylation sites in conjunction with in vitro phosphorylation assays, we determined the lamin A/C phosphoepitope(s) recognized by P-STM. We found that phosphorylation of Thr-19 is required for generating the P-STM phosphoepitope in lamin A/C and showed that it could be created in vitro by p34cdc2/cyclin B kinase (CDK1)-catalyzed phosphorylation of lamin A/C immunoprecipitated from unsynchronized HeLa S3 cells. To further explore changes in lamin A/C phosphorylation in living cells, we precisely quantified the phosphorylation levels of Thr-19 and other sites in lamin A/C isolated from HeLa S3 cells at interphase and mitosis using the SILAC method and liquid chromatography-tandem mass spectrometry. The results showed that the levels of phosphorylated Thr-19, Ser-22 and Ser-392 in both lamins A and C, and Ser-636 in lamin A only, increased ~2- to 6-fold in mitotic HeLa S3 cells. Conclusions Collectively, our results demonstrate that P-STM is a useful tool for detecting Thr-19-phosphorylated lamin A/C in cells and reveal quantitative changes in the phosphorylation status of major lamin A/C phosphorylation sites during mitosis.
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Affiliation(s)
- Jeng-Ting Chen
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China
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Fan CW, Chen CY, Chen KT, Shen CR, Kuo YB, Chen YS, Chou YP, Wei WS, Chan EC. Blockade of phospholipid scramblase 1 with its N-terminal domain antibody reduces tumorigenesis of colorectal carcinomas in vitro and in vivo. J Transl Med 2012; 10:254. [PMID: 23259795 PMCID: PMC3551821 DOI: 10.1186/1479-5876-10-254] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 12/19/2012] [Indexed: 12/04/2022] Open
Abstract
Background Membrane-bound phospholipid scramblase 1 (PLSCR1) is involved in both lipid trafficking and cell signaling. Previously, we showed that PLSCR1 is overexpressed in many colorectal carcinomas (CRCs). In the present study, we investigated the tumorigenic role of PLSCR1 in CRC and suggest that it is a potential therapeutic target. Methods To identify PLSCR1 as a therapeutic target, we studied the tumorigenic properties of CRC cell lines treated with a monoclonal antibody (NP1) against the N-terminus of PLSCR1 in vitro and in vivo. We also investigated cell cycle status and epidermal growth factor receptor–related pathways and downstream effectors of PLSCR1 after blocking its function with NP1. Results Treating CRC cells with NP1 in vitro and in vivo decreased cell proliferation, anchorage-independent growth, migration, and invasion. Adding NP1 to the CRC cell line HT29 caused arrest at G1/S. Treating HT29 cells with NP1 significantly decreased the expression of cyclin D1 and phosphorylation levels of Src, the adaptor protein Shc, and Erks. The reduced level of cyclin D1 led to an increase in the activated form of the tumor suppressor retinoblastoma protein via dephosphorylation. These actions led to attenuation of tumorigenesis. Conclusions Therefore, PLSCR1 may serve as a potential therapeutic target for CRC.
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Affiliation(s)
- Chung-Wei Fan
- Department of Colorectal Surgery, Chang Gung Memorial Hospital, Keelung, Taiwan
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Chen G, Dimitriou I, Milne L, Lang KS, Lang PA, Fine N, Ohashi PS, Kubes P, Rottapel R. The 3BP2 adapter protein is required for chemoattractant-mediated neutrophil activation. THE JOURNAL OF IMMUNOLOGY 2012; 189:2138-50. [PMID: 22815290 DOI: 10.4049/jimmunol.1103184] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
3BP2 is a pleckstrin homology and Src homology 2 domain-containing adapter protein mutated in cherubism, a rare autosomal-dominant human bone disorder. Previously, we have demonstrated a functional role for 3BP2 in peripheral B cell development and in peritoneal B1 and splenic marginal zone B cell-mediated Ab responses. In this study, we show that 3BP2 is required for G protein-coupled receptor-mediated neutrophil functions. Neutrophils derived from 3BP2-deficient (Sh3bp2-/-) mice failed to polarize their actin cytoskeleton or migrate in response to a gradient of chemotactic peptide, fMLF. Sh3bp2-/- neutrophils failed to adhere, crawl, and emigrate out of the vasculature in response to fMLF superfusion. 3BP2 is required for optimal activation of Src family kinases, small GTPase Rac2, neutrophil superoxide anion production, and for Listeria monocytogenes bacterial clearance in vivo. The functional defects observed in Sh3bp2-/- neutrophils may partially be explained by the failure to fully activate Vav1 guanine nucleotide exchange factor and properly localize P-Rex1 guanine nucleotide exchange factor at the leading edge of migrating cells. Our results reveal an obligate requirement for the adapter protein 3BP2 in G protein-coupled receptor-mediated neutrophil function.
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Affiliation(s)
- Grace Chen
- Department of Immunology, University of Toronto, Toronto, Ontario M5S 148, Canada
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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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Wang Z, Oh E, Clapp DW, Chernoff J, Thurmond DC. Inhibition or ablation of p21-activated kinase (PAK1) disrupts glucose homeostatic mechanisms in vivo. J Biol Chem 2011; 286:41359-41367. [PMID: 21969371 DOI: 10.1074/jbc.m111.291500] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The p21-activated kinase PAK1 is implicated in tumorigenesis, and efforts to inhibit PAK1 signaling as a means to induce tumor cell apoptosis are underway. However, PAK1 has also been implicated as a positive effector of mechanisms in clonal pancreatic beta cells and skeletal myotubes that would be crucial to maintaining glucose homeostasis in vivo. Of relevance, human islets of Type 2 diabetic donors contained ~80% less PAK1 protein compared with non-diabetics, implicating PAK1 in islet signaling/scaffolding functions. Mimicking this, islets from PAK1(-/-) knock-out mice exhibited profound defects in the second/sustained-phase of insulin secretion. Reiteration of this specific defect by human islets treated with the PAK1 signaling inhibitor IPA3 revealed PAK1 signaling to be of primary functional importance. Analyses of human and mouse islet beta cell signaling revealed PAK1 activation to be 1) dependent upon Cdc42 abundance, 2) crucial for signaling downstream to activate ERK1/2, but 3) dispensable for cofilin phosphorylation. Importantly, the PAK1(-/-) knock-out mice were found to exhibit whole body glucose intolerance in vivo. Exacerbating this, the PAK1(-/-) knock-out mice also exhibited peripheral insulin resistance. Insulin resistance was coupled to ablation of insulin-stimulated GLUT4 translocation in skeletal muscle from PAK1(-/-) knock-out mice, and in sharp contrast to islet beta cells, skeletal muscle PAK1 loss was underscored by defective cofilin phosphorylation but normal ERK1/2 activation. Taken together, these data provide the first human islet and mammalian in vivo data unveiling the key and crucial roles for differential PAK1 signaling in the multi-tissue regulation of whole body glucose homeostasis.
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Affiliation(s)
- Zhanxiang Wang
- Basic Diabetes Group, Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indianapolis, Indiana 46202
| | - Eunjin Oh
- Basic Diabetes Group, Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indianapolis, Indiana 46202
| | - D Wade Clapp
- Basic Diabetes Group, Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indianapolis, Indiana 46202
| | | | - Debbie C Thurmond
- Basic Diabetes Group, Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indianapolis, Indiana 46202.
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15
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Wang J, Wu JW, Wang ZX. Mechanistic studies of the autoactivation of PAK2: a two-step model of cis initiation followed by trans amplification. J Biol Chem 2010; 286:2689-95. [PMID: 21098037 DOI: 10.1074/jbc.m110.156505] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein kinase activation, via autophosphorylation of the activation loop, is a common regulatory mechanism in phosphorylation-dependent signaling cascades. Despite the prevalence of this reaction and its importance in biological regulation, the molecular mechanisms of autophosphorylation are poorly understood. In this study, we developed a kinetic approach to distinguish quantitatively between cis- and trans-pathways in an autocatalytic reaction. Using this method, we have undertaken a detailed kinetic analysis for the autoactivation mechanism of p21-activated protein kinase 2 (PAK2). PAK2 is regulated in vivo and in vitro by small GTP-binding proteins, Cdc42 and Rac. Full activation of PAK2 requires autophosphorylation of the conserved threonine, Thr(402), in the activation loop of its catalytic kinase domain. Analyses of the time courses of substrate reaction during PAK2 autoactivation suggest that autophosphorylation of Thr(402) in PAK2 obeys a two-step mechanism of cis initiation, followed by trans amplification. The unphosphorylated PAK2 undergoes an intramolecular (cis) autophosphorylation on Thr(402) to produce phosphorylated PAK2, and this newly formed active PAK2 then phosphorylates other PAK2 molecules at Thr(402) in an intermolecular (trans) manner. Based on the kinetic equation derived, all microscopic kinetic constants for the cis and trans autophosphorylation have been estimated quantitatively. The advantage of the new method is not only its usefulness in the study of fast activation reactions, but its convenience in the study of substrate effects on modification reaction. It would be particularly useful when the regulatory mechanism of the autophosphorylation reaction toward certain enzymes is being assessed.
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Affiliation(s)
- Jue Wang
- MOE Key Laboratory for Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, PR China
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16
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Why an A-loop phospho-mimetic fails to activate PAK1: understanding an inaccessible kinase state by molecular dynamics simulations. Structure 2010; 18:879-90. [PMID: 20637424 DOI: 10.1016/j.str.2010.04.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 03/30/2010] [Accepted: 04/16/2010] [Indexed: 11/21/2022]
Abstract
Crystal structures of inactive PAK1(K299R) and the activation (A)-loop phospho-mimetic PAK1(T423E) have suggested that the kinase domain is in an active state regardless of activation loop status. Contrary to a large body of literature, we find that neither is PAK1(T423E) active in cells, nor does it exhibit significant activity in vitro. To explain these discrepancies all-atom molecular dynamics (MD) simulations of PAK1(phospho-T423) in complex with ATP and substrate were performed. These simulations point to a key interaction between PAK1 Lys308, at the end of the alphaC helix, and the pThr423 phosphate group, not seen in X-ray structures. The orthologous PAK4 Arg359 fulfills the same role in immobilizing the alphaC helix. These in silico predictions were validated by experimental mutagenesis of PAK1 and PAK4. The simulations explain why the PAK1 A-loop phospho-mimetic is inactive, but also point to a key functional interaction likely found in other protein kinases.
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17
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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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18
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Chi LM, Lee CW, Chang KP, Hao SP, Lee HM, Liang Y, Hsueh C, Yu CJ, Lee IN, Chang YJ, Lee SY, Yeh YM, Chang YS, Chien KY, Yu JS. Enhanced interferon signaling pathway in oral cancer revealed by quantitative proteome analysis of microdissected specimens using 16O/18O labeling and integrated two-dimensional LC-ESI-MALDI tandem MS. Mol Cell Proteomics 2009; 8:1453-74. [PMID: 19297561 PMCID: PMC2709179 DOI: 10.1074/mcp.m800460-mcp200] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Accepted: 03/09/2009] [Indexed: 11/06/2022] Open
Abstract
Oral squamous cell carcinoma (OSCC) remains one of the most common cancers worldwide, and the mortality rate of this disease has increased in recent years. No molecular markers are available to assist with the early detection and therapeutic evaluation of OSCC; thus, identification of differentially expressed proteins may assist with the detection of potential disease markers and shed light on the molecular mechanisms of OSCC pathogenesis. We performed a multidimensional (16)O/(18)O proteomics analysis using an integrated ESI-ion trap and MALDI-TOF/TOF MS system and a computational data analysis pipeline to identify proteins that are differentially expressed in microdissected OSCC tumor cells relative to adjacent non-tumor epithelia. We identified 1233 unique proteins in microdissected oral squamous epithelia obtained from three pairs of OSCC specimens with a false discovery rate of <3%. Among these, 977 proteins were quantified between tumor and non-tumor cells. Our data revealed 80 dysregulated proteins (53 up-regulated and 27 down-regulated) when a 2.5-fold change was used as the threshold. Immunohistochemical staining and Western blot analyses were performed to confirm the overexpression of 12 up-regulated proteins in OSCC tissues. When the biological roles of 80 differentially expressed proteins were assessed via MetaCore analysis, the interferon (IFN) signaling pathway emerged as one of the most significantly altered pathways in OSCC. As many as 20% (10 of 53) of the up-regulated proteins belonged to the IFN-stimulated gene (ISG) family, including ubiquitin cross-reactive protein (UCRP)/ISG15. Using head-and-neck cancer tissue microarrays, we determined that UCRP is overexpressed in the majority of cheek and tongue cancers and in several cases of larynx cancer. In addition, we found that IFN-beta stimulates UCRP expression in oral cancer cells and enhances their motility in vitro. Our findings shed new light on OSCC pathogenesis and provide a basis for the future development of novel biomarkers.
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MESH Headings
- Biomarkers, Tumor/metabolism
- Carcinoma, Squamous Cell/chemistry
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/pathology
- Cell Line, Tumor
- Chromatography, Liquid/methods
- Databases, Protein
- Gene Expression Regulation, Neoplastic
- Humans
- Immunohistochemistry
- Interferons/metabolism
- Male
- Microdissection
- Molecular Sequence Data
- Mouth Neoplasms/chemistry
- Mouth Neoplasms/metabolism
- Mouth Neoplasms/pathology
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Oxygen Isotopes/metabolism
- Proteome/analysis
- Signal Transduction/physiology
- Spectrometry, Mass, Electrospray Ionization/methods
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
- Tandem Mass Spectrometry/methods
- Tissue Array Analysis
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Affiliation(s)
- Lang-Ming Chi
- From the ‡Molecular Medicine Research Center
- Departments of §Medical Research and Development
| | | | | | | | | | - Ying Liang
- From the ‡Molecular Medicine Research Center
| | - Chuen Hsueh
- From the ‡Molecular Medicine Research Center
- ‖Pathology, Chang Gung Memorial Hospital, Tao-Yuan 333, Taiwan
| | - Chia-Jung Yu
- From the ‡Molecular Medicine Research Center
- **Department of Biochemistry and Molecular Biology, and
| | - I-Neng Lee
- From the ‡Molecular Medicine Research Center
| | | | | | - Yuan-Ming Yeh
- ‡‡Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University and
| | - Yu-Sun Chang
- From the ‡Molecular Medicine Research Center
- ‡‡Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University and
| | - Kun-Yi Chien
- From the ‡Molecular Medicine Research Center
- **Department of Biochemistry and Molecular Biology, and
| | - Jau-Song Yu
- From the ‡Molecular Medicine Research Center
- **Department of Biochemistry and Molecular Biology, and
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19
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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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20
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Ni MH, Wu CC, Chan WH, Chien KY, Yu JS. GSK-3 mediates the okadaic acid-induced modification of collapsin response mediator protein-2 in human SK-N-SH neuroblastoma cells. J Cell Biochem 2008; 103:1833-48. [PMID: 17902168 DOI: 10.1002/jcb.21575] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Collapsin response mediator protein-2 (CRMP-2), a phosphoprotein involved in axonal outgrowth and microtubule dynamics, is aberrantly phosphorylated in Alzheimer's disease (AD) brain. Alteration of glycogen synthase kinase-3 (GSK-3) activity is associated with the pathogenesis of AD. Here, we show that CRMP-2 is one of the major substrates for GSK-3 in pig brain extracts. Both GSK-3alpha and 3beta phosphorylate purified pig brain CRMP-2 and significantly alter its mobility in SDS-gels, resembling the CRMP-2 modification observed in AD brain. Interestingly, this modification can be detected in SK-N-SH neuroblastoma cells treated with a phosphatase inhibitor, okadaic acid (OA), and GSK-3 inhibitors completely block this OA-induced event. Knockdown of both GSK-3alpha and 3beta, but not either kinase alone, impairs OA-induced modification of CRMP-2. Mutation of Ser-518 or Ser-522 of CRMP-2, which are highly phosphorylated in AD brain, to Ala blocks the OA-induced modification of CRMP-2 in SK-N-SH cells. Ser-522 prephosphorylated by Cdk5 is required for subsequent GSK-3alpha-mediated phosphorylation of CRMP-2 in vitro. Collectively, our results demonstrate for the first time that OA can induce phosphorylation of CRMP-2 in SK-N-SH cells at sites aberrantly phosphorylated in AD brain, and both GSK-3alpha and 3beta and Ser-522 kinase(s) are involved in this process.
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Affiliation(s)
- Mei-Hui Ni
- Graduate Institute of Basic Medical Sciences, Medical College of Chang Gung University, Tao-Yuan, Taiwan, Republic of China
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21
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Weng LP, Wu CC, Hsu BL, Chi LM, Liang Y, Tseng CP, Hsieh LL, Yu JS. Secretome-Based Identification of Mac-2 Binding Protein as a Potential Oral Cancer Marker Involved in Cell Growth and Motility. J Proteome Res 2008; 7:3765-75. [DOI: 10.1021/pr800042n] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Li-Ping Weng
- Graduate Institute of Biomedical Sciences, Proteomics Core Laboratory, Molecular Medicine Research Center, Department of Cell and Molecular Biology, Department of Public Health, and Graduate Institute of Medical Biotechnology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China, and Department of Medical Research and Development, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
| | - Chih-Ching Wu
- Graduate Institute of Biomedical Sciences, Proteomics Core Laboratory, Molecular Medicine Research Center, Department of Cell and Molecular Biology, Department of Public Health, and Graduate Institute of Medical Biotechnology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China, and Department of Medical Research and Development, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
| | - Bao-Lian Hsu
- Graduate Institute of Biomedical Sciences, Proteomics Core Laboratory, Molecular Medicine Research Center, Department of Cell and Molecular Biology, Department of Public Health, and Graduate Institute of Medical Biotechnology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China, and Department of Medical Research and Development, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
| | - Lang-Ming Chi
- Graduate Institute of Biomedical Sciences, Proteomics Core Laboratory, Molecular Medicine Research Center, Department of Cell and Molecular Biology, Department of Public Health, and Graduate Institute of Medical Biotechnology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China, and Department of Medical Research and Development, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
| | - Ying Liang
- Graduate Institute of Biomedical Sciences, Proteomics Core Laboratory, Molecular Medicine Research Center, Department of Cell and Molecular Biology, Department of Public Health, and Graduate Institute of Medical Biotechnology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China, and Department of Medical Research and Development, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
| | - Ching-Ping Tseng
- Graduate Institute of Biomedical Sciences, Proteomics Core Laboratory, Molecular Medicine Research Center, Department of Cell and Molecular Biology, Department of Public Health, and Graduate Institute of Medical Biotechnology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China, and Department of Medical Research and Development, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
| | - Ling-Ling Hsieh
- Graduate Institute of Biomedical Sciences, Proteomics Core Laboratory, Molecular Medicine Research Center, Department of Cell and Molecular Biology, Department of Public Health, and Graduate Institute of Medical Biotechnology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China, and Department of Medical Research and Development, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
| | - Jau-Song Yu
- Graduate Institute of Biomedical Sciences, Proteomics Core Laboratory, Molecular Medicine Research Center, Department of Cell and Molecular Biology, Department of Public Health, and Graduate Institute of Medical Biotechnology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China, and Department of Medical Research and Development, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
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22
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Abstract
The mycotoxin citrinin (CTN) is a natural contaminant in foodstuffs and animal feeds, and exerts cytotoxic and genotoxic effects on various mammalian cells. CTN causes cell injury, including apoptosis. However, its precise regulatory mechanisms of action, particularly in stem cells and embryos, are currently unclear. Recent studies show that CTN has cytotoxic effects on mouse embryonic stem cells and blastocysts, and is associated with defects in their subsequent development, both in vitro and in vivo. Experiments with the embryonic stem cell line, ESC-B5, disclose that CTN induces apoptosis via several mechanisms, including ROS generation, increased cytoplasmic free calcium levels, intracellular nitric oxide production, enhanced Bax/Bcl-2 ratio, loss of mitochondrial membrane potential, cytochrome c release, activation of caspase-9 and caspase-3, and p21-activated protein kinase 2 and c-Jun N-terminal protein kinase activation. Additional studies show that CTN promotes cell death via inactivation of the HSP90/multi-chaperone complex and subsequent degradation of Ras and Raf-1, further inhibiting anti-apoptotic processes such as the Ras-->ERK signal transduction pathway. On the basis of these findings, we propose a model for CTN-induced cell injury signalling cascades in embryonic stem cells and blastocysts.
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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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23
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Huang WC, Hsu RM, Chi LM, Leu YL, Chang YS, Yu JS. Selective downregulation of EGF receptor and downstream MAPK pathway in human cancer cell lines by active components partially purified from the seeds of Livistona chinensis R. Brown. Cancer Lett 2007; 248:137-46. [PMID: 16919867 DOI: 10.1016/j.canlet.2006.06.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Revised: 06/06/2006] [Accepted: 06/29/2006] [Indexed: 11/16/2022]
Abstract
Deregulation of protein kinase-mediated signaling events is one of the major causes to malignant transformation. In this work, we tried to purify protein kinase inhibitory activity and antitumor activity from ethanol extracts of the seeds of Livistona chinensis R. Brown (LC), a traditional herb used for the treatment of nasopharyngeal carcinoma (NPC). Both activities were found to be co-purified in various chromatography steps, and a highly purified fraction, LC-X, was obtained and its biological effects were characterized further. LC-X inhibited the activities of various protein kinases in vitro, including PAK2, PKA, PKC, GSK-3alpha, CK2, mitogen-activated protein kinase (MAPK), and JNK1, with IC(50) between approximately 1 and 40microg/ml. The proliferation of two NPC (NPC-TW02 and -TW04) and one breast cancer (MCF-7) cell lines, but not the epidermoid (A431) and cervical (HeLa) carcinoma cell lines, were significantly blocked by LC-X at the dose of >50microg/ml. Cell cycle arrested at G(2)/M phase and apoptosis were detected in NPC-TW02 cells treated with LC-X for 24h. Further studies revealed that epidermal growth factor (EGF)-induced activation of epidermal growth factor receptor (EGFR) and MAPK could be potently inhibited by LC-X in both NPC-TW02 and A431cells in a dose-dependent manner. More interestingly, the level of EGFR protein detected by Western blot decreased drastically in LC-X-treated A431 and NPC-TW02 cells in a dose- and time-dependent fashion. Further analysis of the plasma membrane and cytosolic fractions from LC-X-treated and untreated A431 cells showed that a 170kDa protein selectively disappeared from the plasma membrane of LC-X-treated cells. The protein was identified as EGFR by MALDI-TOF mass spectrometry, indicating EGFR as a selective target for LC-X. Moreover, the electrophoretic mobility of purified EGFR in SDS-PAGE was altered dramatically post LC-X treatment, suggesting that LC-X may chemically modify EGFR. In conclusion, the active components with both antitumor and protein kinases inhibitor activities were highly purified from LC, which can inhibit the EGF signaling events mainly through EGFR modification. Blockage of the functions of EGFR may account for the antitumor activity of these active components.
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Affiliation(s)
- Wen-Chuang Huang
- Graduate Institute of Basic Medical Sciences, Medical College of Chang Gung University, Tao-Yuan, Taiwan, Republic of China
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24
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Chen CD, Wang CS, Huang YH, Chien KY, Liang Y, Chen WJ, Lin KH. Overexpression of CLIC1 in human gastric carcinoma and its clinicopathological significance. Proteomics 2007; 7:155-67. [PMID: 17154271 DOI: 10.1002/pmic.200600663] [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: 12/22/2022]
Abstract
Gastric cancer is the second most common cancer worldwide and the fifth leading cause of cancer-related death in Taiwan. Identification of biomarkers is essential to improve patient survival. Fifty aberrantly expressed proteins were identified using 2-DE combined with MALDI TOF MS and were grouped based on their function. The overexpression of proteins was confirmed using real-time quantitative RT-PCR, Western blot, and immunohistochemical analysis. The clinicopathological correlations and prognostic significance of these aberrantly expressed proteins were evaluated to determine the novel gastric cancer biomarkers. In this study, expression of chloride intracellular channel 1 (CLIC1) is significantly up-regulated in 67.9% of gastric patients and was selected for further study. The CLIC1 expression in tumor tissues was increased by 1.95-fold (range, 0.01-6.19-fold) compared with that expressed by adjacent noncancerous mucosa. Elevated CLIC1 expression was strongly correlated with lymph node metastasis, lymphatic invasion, perineural invasion, and pathological staging. Additionally, the 5-year survival rate for the low CLIC1 expression group (n = 28; <1.72-fold) was higher than that for the high CLIC1 expression group (n = 28; >or=1.72-fold) (log rank, p = 0.0300). Experimental results indicate that overexpression of CLIC1 is a potential prognostic marker for gastric cancer.
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Affiliation(s)
- Chi-De Chen
- Department of Biochemistry, Chang Gung University, Taoyuan, Taiwan, Republic of China
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25
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Wang Z, Oh E, Thurmond DC. Glucose-stimulated Cdc42 signaling is essential for the second phase of insulin secretion. J Biol Chem 2007; 282:9536-9546. [PMID: 17289663 PMCID: PMC2396332 DOI: 10.1074/jbc.m610553200] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The small Rho family GTPases Cdc42 and Rac1 have each been shown to function in insulin exocytosis and are presumed to function in actin remodeling and insulin granule mobilization. However, whether either GTPase is required for the mobilization phase of insulin release (second phase) and are linked in a common signaling pathway has remained unknown. Here we demonstrate that small interfering RNA-mediated depletion of Cdc42 from isolated islets results in the selective loss of second phase insulin release. Consistent with a role in this nutrient-dependent phase, Cdc42 activation was detected exclusively in response to D-glucose and was unresponsive to KCl or non-metabolizable glucose analogs in MIN6 beta-cells. Cdc42 activation occurred early in secretion (3 min), whereas Rac1 activation required approximately 15-20 min, suggesting Cdc42 as proximal and Rac1 as distal regulators of second-phase secretion. Importantly, Rac1 activation and function was linked in a common pathway downstream of Cdc42; Cdc42 depletion ablated glucose-induced Rac1 activation, and expression of constitutively active Rac1 in Cdc42-depleted cells functionally restored glucose-stimulated insulin secretion. Occurring at a time midway between Cdc42 and Rac1 activations was the phosphorylation of p21-activated-kinase 1 (Pak1), and this phosphorylation event required Cdc42. Moreover, small interfering RNA-mediated Pak1 depletion abolished Rac1 activation and glucose-stimulated insulin release, suggesting that Pak1 may mediate the link between Cdc42 and Rac1 in this pathway. Taken together, these data substantiate the existence of a novel signaling pathway in the islet beta-cell whereby Cdc42 functions as a key proximal transmitter of the glucose signal early in stimulus-secretion coupling to support the later stage of insulin release.
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Affiliation(s)
- Zhanxiang Wang
- Department of Biochemistry and Molecular Biology and Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Eunjin Oh
- Department of Biochemistry and Molecular Biology and Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Debbie C Thurmond
- Department of Biochemistry and Molecular Biology and Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, Indiana 46202.
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26
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Lu TJ, Lai WY, Huang CYF, Hsieh WJ, Yu JS, Hsieh YJ, Chang WT, Leu TH, Chang WC, Chuang WJ, Tang MJ, Chen TY, Lu TL, Lai MD. Inhibition of cell migration by autophosphorylated mammalian sterile 20-like kinase 3 (MST3) involves paxillin and protein-tyrosine phosphatase-PEST. J Biol Chem 2006; 281:38405-17. [PMID: 17046825 DOI: 10.1074/jbc.m605035200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MST3 is a member of the sterile-20 protein kinase family with a unique preference for manganese ion as a cofactor in vitro; however, its biological function is largely unknown. Suppression of endogenous MST3 by small interference RNA enhanced cellular migration in MCF-7 cells with reduced expression of E-cadherin at the edge of migrating cells. The alteration of cellular migration and protruding can be rescued by RNA interference-resistant MST3. The expression of surface integrin and Golgi apparatus was not altered, but phosphorylation on tyrosine 118 and tyrosine 31 of paxillin was attenuated by MST3 small interfering RNA (siRNA). Threonine 178 was determined to be one of the two main autophosphorylation sites of MST3 in vitro. Mutant T178A MST3, containing alanine instead of threonine at codon 178, lost autophosphorylation and kinase activities. Overexpression of wild type MST3, but not the T178A mutant MST3, inhibited migration and spreading in Madin-Darby canine kidney cells. MST3 could phosphorylate the protein-tyrosine phosphatase (PTP)-PEST and inhibit the tyrosine phosphatase activity of PTP-PEST. We conclude that MST3 inhibits cell migration in a fashion dependent on autophosphorylation and may regulate paxillin phosphorylation through tyrosine phosphatase PTP-PEST.
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Affiliation(s)
- Te-Jung Lu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan
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27
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Abstract
The pivotal role of kinases in signal transduction and cellular regulation has lent them considerable appeal as pharmacological targets across a broad spectrum of cancers. p21-activated kinases (Paks) are serine/threonine kinases that function as downstream nodes for various oncogenic signalling pathways. Paks are well-known regulators of cytoskeletal remodelling and cell motility, but have recently also been shown to promote cell proliferation, regulate apoptosis and accelerate mitotic abnormalities, which results in tumour formation and cell invasiveness. Alterations in Pak expression have been detected in human tumours, which makes them an attractive new therapeutic target.
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Affiliation(s)
- Rakesh Kumar
- The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030-4009, USA.
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28
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Wu CC, Chien KY, Tsang NM, Chang KP, Hao SP, Tsao CH, Chang YS, Yu JS. Cancer cell-secreted proteomes as a basis for searching potential tumor markers: nasopharyngeal carcinoma as a model. Proteomics 2005; 5:3173-82. [PMID: 16035111 DOI: 10.1002/pmic.200401133] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Nasopharyngeal carcinoma (NPC) is commonly diagnosed late due to its deep location and vague symptoms. To identify biomarkers for early NPC diagnosis, secreted proteomes of two NPC cell lines were analyzed. Proteins in the NPC cell-line cultured media were systematically identified by SDS-PAGE combined with MALDI-TOF MS. Twenty-three proteins were found in cultured media from both NPC cell lines. Among them, fibronectin, Mac-2 binding protein (Mac-2 BP), and plasminogen activator inhibitor 1 (PAI-1) were further confirmed by Western blot analysis. These three proteins were highly expressed in NPC biopsies, but weakly or not expressed in normal nasopharyngeal tissues. The serum levels of the three proteins were significantly higher in NPC patients (n = 46) than in normal controls (n = 47) (p < 0.01). NPC nude mice model (n = 9) also showed elevated levels of serum Mac-2 BP and PAI-1 compared with tumor-free mice (n = 9) (p < 0.01). Systematic analysis of cancer cell-secreted proteomes combined with animal tumor models can be a feasible, convenient strategy for searching multiple potential tumor markers. Furthermore, our work shows that fibronectin, Mac-2 BP, and PAI-1 may be potential markers for diagnosis of NPC.
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Affiliation(s)
- Chih-Ching Wu
- Department of Cell and Molecular Biology, Chang Gung University, Tao-Yuan, Taiwan, Republic of China
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29
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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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30
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Zhao ZS, Manser E. PAK and other Rho-associated kinases--effectors with surprisingly diverse mechanisms of regulation. Biochem J 2005; 386:201-14. [PMID: 15548136 PMCID: PMC1134783 DOI: 10.1042/bj20041638] [Citation(s) in RCA: 201] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 11/09/2004] [Accepted: 11/17/2004] [Indexed: 11/17/2022]
Abstract
The Rho GTPases are a family of molecular switches that are critical regulators of signal transduction pathways in eukaryotic cells. They are known principally for their role in regulating the cytoskeleton, and do so by recruiting a variety of downstream effector proteins. Kinases form an important class of Rho effector, and part of the biological complexity brought about by switching on a single GTPase results from downstream phosphorylation cascades. Here we focus on our current understanding of the way in which different Rho-associated serine/threonine kinases, denoted PAK (p21-activated kinase), MLK (mixed-lineage kinase), ROK (Rho-kinase), MRCK (myotonin-related Cdc42-binding kinase), CRIK (citron kinase) and PKN (protein kinase novel), interact with and are regulated by their partner GTPases. All of these kinases have in common an ability to dimerize, and in most cases interact with a variety of other proteins that are important for their function. A diversity of known structures underpin the Rho GTPase-kinase interaction, but only in the case of PAK do we have a good molecular understanding of kinase regulation. The ability of Rho GTPases to co-ordinate spatial and temporal phosphorylation events explains in part their prominent role in eukaryotic cell biology.
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Key Words
- cdc42
- mlk (mixed-lineage kinase)
- pak (p21-activated kinase)
- rac
- rho
- rok (rho-kinase)
- acc, anti-parallel coiled-coil
- crib, cdc42 and rac interactive binding
- crik, citron kinase
- crmp, collapsin response mediator protein
- dmpk, myotonic dystrophy kinase
- gef, guanine nucleotide exchange factor
- git1, g-protein-coupled receptor kinase-interacting target 1
- hsp90, heat shock protein 90
- jnk, c-jun n-terminal kinase
- ki, kinase inhibitory
- kim, ki motif
- limk, lim domain kinase
- mapk, mitogen-activated protein kinase
- mbs, myosin-binding subunit
- mekk, mapk/erk (extracellular-signal-regulated kinase) kinase kinase
- mkk, mapk kinase
- mlk, mixed-lineage kinase
- mrck, myotonin-related cdc42-binding kinase
- pak, p21-activated kinase
- pbd, p21-binding domain
- pdk1, 3-phosphoinositide-dependent kinase 1
- ph, pleckstrin homology
- pix, pak-interacting exchange factor
- pkc, protein kinase c
- pkn, protein kinase novel
- pp1, protein phosphatase type 1
- r-mlc, regulatory myosin light chain
- rok, rho-kinase
- sh3, src homology 3
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Affiliation(s)
- Zhou-shen Zhao
- GSK-IMCB Laboratory, Institute of Molecular and Cell Biology, Proteos Building, 61 Biopolis Drive, Singapore 138673
| | - Ed Manser
- GSK-IMCB Laboratory, Institute of Molecular and Cell Biology, Proteos Building, 61 Biopolis Drive, Singapore 138673
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31
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Mishima W, Suzuki A, Yamaji S, Yoshimi R, Ueda A, Kaneko T, Tanaka J, Miwa Y, Ohno S, Ishigatsubo Y. The first CH domain of affixin activates Cdc42 and Rac1 through alphaPIX, a Cdc42/Rac1-specific guanine nucleotide exchanging factor. Genes Cells 2004; 9:193-204. [PMID: 15005707 DOI: 10.1111/j.1356-9597.2004.00717.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Rho GTPases, Cdc42 and Rac1, play pivotal roles in cell migration by efficiently integrating cell-substrate adhesion and actin polymerization. Although it has been suggested that integrins stimulate these Rho GTPases via some of integrin binding proteins such as focal adhesion kinase (FAK) and paxillin, the precise molecular mechanism is largely unknown. In this study, we showed that the over-expression of RP1 corresponding to the first CH domain (CH1) of affixin, an integrin-linked kinase (ILK)-binding protein, induced a significant actin reorganization in MDCK cells by activating Cdc42/Rac1. Affixin full length and RP1 co-immunoprecipitated with alphaPIX, a Cdc42/Rac1-specific guanine nucleotide exchanging factor (GEF), and they co-localized at the tips of lamellipodia in motile cells. The involvement of alphaPIX in the RP1-induced Cdc42 activation was demonstrated by the significant dominant negative effect of a point mutant of alphaPIX, alphaPIX (L383R, L384S), lacking GEF activity. Our data strongly support that ILK and affixin provide a novel signalling pathway that links integrin signalling to Cdc42/Rac1 activation.
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Affiliation(s)
- Wataru Mishima
- Department of Internal Medicine and Clinical Immunology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura Kanazawa-ku, Yokohama 236-0004 Japan
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32
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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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33
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Schrantz N, da Silva Correia J, Fowler B, Ge Q, Sun Z, Bokoch GM. Mechanism of p21-activated kinase 6-mediated inhibition of androgen receptor signaling. J Biol Chem 2003; 279:1922-31. [PMID: 14573606 DOI: 10.1074/jbc.m311145200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
PAK6 was first identified as an androgen receptor (AR)-interacting protein able to inhibit AR-mediated transcriptional responses. PAK6 is a serine/threonine kinase belonging to the p21-activated kinase (PAK) family implicated in actin reorganization and cell motility, gene transcription, apoptosis, and cell transformation. We investigated the biochemical basis for inhibition of AR signaling by PAK6. We compared the kinase activity of PAK6 with two other well characterized members of the PAK family, PAK1 and PAK4. Like PAK4, PAK6 possesses a constitutive basal kinase activity that, unlike PAK1, is not modulated by the binding of active Rac or Cdc42 GTPases. In order to test the involvement of PAK6 kinase activity in suppression of AR-mediated transcription, we generated kinase-dead (K436A) and kinase-active (S531N) mutants of PAK6. We show that PAK6 kinase activity is required for effective PAK6-induced repression of AR signaling. Suppression does not depend upon GTPase binding to PAK6 and is not mimicked by the closely related PAK1 and PAK4 isoforms. Kinase-dependent inhibition by PAK6 extended to the enhanced AR-mediated transcription seen in the presence of coactivating molecules and to the action of AR coinhibitors. Active PAK6 inhibited nuclear translocation of the stimulated AR, suggesting a possible mechanism for inhibition of AR responsiveness. Finally, we observe that autophosphorylated, active PAK6 protein is differently expressed among prostate cancer cell lines. Modulation of PAK6 activity may be responsible for regulation of AR signaling in various forms of prostate cancer.
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Affiliation(s)
- Nicolas Schrantz
- Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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34
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Chi LM, Yu JS, Chang YS. Identification of protein kinase CK2 as a potent kinase of Epstein-Barr virus latent membrane protein 1. Biochem Biophys Res Commun 2002; 294:586-91. [PMID: 12056807 DOI: 10.1016/s0006-291x(02)00515-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The C-terminus of latent membrane protein 1 (LMP1) can be phosphorylated in vivo. However, the protein kinase responsible for LMP1 phosphorylation has not yet been identified. In this study, GST fusion proteins containing the C-terminus of LMP1 were generated and used as substrates to survey the kinases that phosphorylate LMP1. Among several purified protein kinases tested, only protein kinase CK2 (CK2) could specifically phosphorylate LMP1. Using the in-gel kinase assay in the absence and presence of a selective CK2 inhibitor, 4,5,6,7-tetrabromobenzotriazole, CK2 was determined to be the major kinase to phosphorylate LMP1 in lymphoma and epithelial cell lines. This is the first study to show that CK2 is a potent kinase to phosphorylate LMP1 in vitro.
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Affiliation(s)
- Lang-Ming Chi
- Department of Medical Technology, Yuan-Pei Institute of Science and Technology, Hsinchu, Taiwan, ROC.
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35
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Huang HC, Yu JS, Tsay CC, Lin JH, Huang SY, Fang WT, Liu YC, Tzang BS, Lee WC. Purification and characterization of porcine testis 90-kDa heat shock protein (HSP90) as a substrate for various protein kinases. JOURNAL OF PROTEIN CHEMISTRY 2002; 21:111-21. [PMID: 11934275 DOI: 10.1023/a:1014528328673] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We purified a large quantity of HSP90 from porcine testis by hydroxylapatite (HA-HSP90) and SDS-PAGE/electroelution (eluted-HSP90) to explore the molecular mechanism of HSP90 phosphorylation affecting its metabolism. The purified HSP90 was used as an antigen to raise polyclonal antibodies in rabbits. Immunoblot analysis revealed that most purified HSP90 was HSP90alpha. Compared with the commercial anti-HSP90 antibody, the polyclonal antibody raised in this study could specifically detect the testis HSP90 and immunoprecipitate HSP90 from tissue homogenates or cell extracts. Incubation of the purified HSP90 or HSP90 immunoprecipitated from extracts of human A431 cells, Balb/c 3T3 fibroblasts, and porcine testis with [gamma-32P]ATP/Mg2+ resulted in phosphorylation of HSP90. However, the eluted-HSP90 lost its phosphorylation ability when incubated with [gamma-32P]ATP x Mg2+ alone but could be phosphorylated by various protein kinases, including PKA, CKII, kinase FA/GSK-3 alpha, and AK. The order of phosphorylation of HSP90 by these kinases is PKA = CKII > AK >> kinase FA/GSK-3 alpha.
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Affiliation(s)
- Hsiu-Chin Huang
- Division of Biotechnology, Animal Technology Institute Taiwan, ROC
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36
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Buchwald G, Hostinova E, Rudolph MG, Kraemer A, Sickmann A, Meyer HE, Scheffzek K, Wittinghofer A. Conformational switch and role of phosphorylation in PAK activation. Mol Cell Biol 2001; 21:5179-89. [PMID: 11438672 PMCID: PMC87242 DOI: 10.1128/mcb.21.15.5179-5189.2001] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
p21-activated protein kinases (PAKs) are involved in signal transduction processes initiating a variety of biological responses. They become activated by interaction with Rho-type small GTP-binding proteins Rac and Cdc42 in the GTP-bound conformation, thereby relieving the inhibition of the regulatory domain (RD) on the catalytic domain (CD). Here we report on the mechanism of activation and show that proteolytic digestion of PAK produces a heterodimeric RD-CD complex consisting of a regulatory fragment (residues 57 to 200) and a catalytic fragment (residues 201 to 491), which is active in the absence of Cdc42. Cdc42-GppNHp binds with low affinity (K(d) 0.6 microM) to intact kinase, whereas the affinity to the isolated regulatory fragment is much higher (K(d) 18 nM), suggesting that the difference in binding energy is used for the conformational change leading to activation. The full-length kinase, the isolated RD, and surprisingly also their complexes with Cdc42 behave as dimers on a gel filtration column. Cdc42-GppNHp interaction with the RD-CD complex is also of low affinity and does not dissociate the RD from the CD. After autophosphorylation of the kinase domain, Cdc42 binds with high (14 nM) affinity and dissociates the RD-CD complex. Assuming that the RD-CD complex mimics the interaction in native PAK, this indicates that the small G protein may not simply release the RD from the CD. It acts in a more subtle allosteric control mechanism to induce autophosphorylation, which in turn induces the release of the RD and thus full activation.
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Affiliation(s)
- G Buchwald
- Max-Planck-Institut für Molekulare Physiologie, 44227 Dortmund, Germany
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37
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Apoptotic signalling cascade in photosensitized human epidermal carcinoma A431 cells: involvement of singlet oxygen, c-Jun N-terminal kinase, caspase-3 and p21-activated kinase 2. Biochem J 2001. [PMID: 10998365 DOI: 10.1042/bj3510221] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Photodynamic treatment (PDT) elicits diverse cellular responses and can also cause apoptosis. In the present study the cascade of signalling events involved in PDT-induced apoptosis was investigated using Rose Bengal (RB) as the photosensitizer, and human epidermal carcinoma A431 cells as the cell model. We show that a 36-kDa kinase detected by an in-gel kinase assay is markedly activated during PDT-triggered apoptosis. Immunoblot analysis revealed that this 36-kDa kinase represents the C-terminal catalytic fragment of p21-activated kinase (PAK)2. Generation of this active fragment of PAK2 is mediated by the caspase family of proteases, which are activated by PDT. The specific caspase inhibitors (acetyl-Asp-Glu-Val-Asp-aldehyde and acetyl-Tyr-Val-Ala-Asp-chloromethylketone) block the PDT-induced caspase-3 activation and subsequent PAK2 cleavage/activation, indicating a major role for the caspase family proteases in PDT-induced apoptosis. Both PDT-induced caspase-3 activation and PAK2 cleavage/activation can be inhibited by the singlet oxygen scavengers, L-histidine and alpha-tocopherol, but not the hydroxyl radical scavenger, mannitol, demonstrating that singlet oxygen is an immediate early-apoptotic signal generated by PDT. In addition, PDT can induce a two-stage activation of the c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) in A431 cells; the early-stage JNK activation is singlet oxygen-dependent, whereas the late-stage JNK activation is mediated by the singlet oxygen-triggered caspase activation. Experiments using anti-sense oligonucleotides against JNK1 and PAK2 further show that during PDT-induced apoptosis the early-stage JNK activation is required for caspase activation, and that the late-stage JNK activation is regulated by the caspase-mediated cleavage/activation of PAK2. Collectively, a model for the PDT-triggered apoptotic signalling cascade with RB is proposed, which involves singlet oxygen, JNK, caspase-3 and PAK2, sequentially.
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38
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King CC, Reilly AM, Knaus UG. Purification and in vitro activities of p21-activated kinases. Methods Enzymol 2001; 325:155-66. [PMID: 11036601 DOI: 10.1016/s0076-6879(00)25440-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- C C King
- Department of Immunology, Scripps Research Institute, La Jolla, California 92037, USA
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39
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Chan WH, Yu JS, Yang SD. Apoptotic signalling cascade in photosensitized human epidermal carcinoma A431 cells: involvement of singlet oxygen, c-Jun N-terminal kinase, caspase-3 and p21-activated kinase 2. Biochem J 2000; 351:221-32. [PMID: 10998365 PMCID: PMC1221353 DOI: 10.1042/0264-6021:3510221] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Photodynamic treatment (PDT) elicits diverse cellular responses and can also cause apoptosis. In the present study the cascade of signalling events involved in PDT-induced apoptosis was investigated using Rose Bengal (RB) as the photosensitizer, and human epidermal carcinoma A431 cells as the cell model. We show that a 36-kDa kinase detected by an in-gel kinase assay is markedly activated during PDT-triggered apoptosis. Immunoblot analysis revealed that this 36-kDa kinase represents the C-terminal catalytic fragment of p21-activated kinase (PAK)2. Generation of this active fragment of PAK2 is mediated by the caspase family of proteases, which are activated by PDT. The specific caspase inhibitors (acetyl-Asp-Glu-Val-Asp-aldehyde and acetyl-Tyr-Val-Ala-Asp-chloromethylketone) block the PDT-induced caspase-3 activation and subsequent PAK2 cleavage/activation, indicating a major role for the caspase family proteases in PDT-induced apoptosis. Both PDT-induced caspase-3 activation and PAK2 cleavage/activation can be inhibited by the singlet oxygen scavengers, L-histidine and alpha-tocopherol, but not the hydroxyl radical scavenger, mannitol, demonstrating that singlet oxygen is an immediate early-apoptotic signal generated by PDT. In addition, PDT can induce a two-stage activation of the c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) in A431 cells; the early-stage JNK activation is singlet oxygen-dependent, whereas the late-stage JNK activation is mediated by the singlet oxygen-triggered caspase activation. Experiments using anti-sense oligonucleotides against JNK1 and PAK2 further show that during PDT-induced apoptosis the early-stage JNK activation is required for caspase activation, and that the late-stage JNK activation is regulated by the caspase-mediated cleavage/activation of PAK2. Collectively, a model for the PDT-triggered apoptotic signalling cascade with RB is proposed, which involves singlet oxygen, JNK, caspase-3 and PAK2, sequentially.
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Affiliation(s)
- W H Chan
- Department of Cell and Molecular Biology, Institute of Basic Medicine, Medical College of Chang Gung University, Tao-Yuan, Taiwan, Republic of China
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40
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Zenke FT, King CC, Bohl BP, Bokoch GM. Identification of a central phosphorylation site in p21-activated kinase regulating autoinhibition and kinase activity. J Biol Chem 1999; 274:32565-73. [PMID: 10551809 DOI: 10.1074/jbc.274.46.32565] [Citation(s) in RCA: 203] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p21-activated kinases (Pak)/Ste20 kinases are regulated in vitro and in vivo by the small GTP-binding proteins Rac and Cdc42 and lipids, such as sphingosine, which stimulate autophosphorylation and phosphorylation of exogenous substrates. The mechanism of Pak activation by these agents remains unclear. We investigated Pak kinase activation in more detail to gain insight into the interplay between the GTPase/sphingosine binding, an intramolecular inhibitory interaction, and autophosphorylation. We present biochemical evidence that an autoinhibitory domain (ID) contained within amino acid residues 67-150 of Pak1 interacts with the carboxyl-terminal kinase domain and that this interaction is regulated in a GTPase-dependent fashion. Cdc42- and sphingosine-stimulated Pak1 activity can be inhibited in trans by recombinant ID peptide, indicating similarities in their mode of activation. However, Pak1, which was autophosphorylated in response to either GTPase or sphingosine, is highly active and is insensitive to inhibition by the ID peptide. We identified phospho-acceptor site threonine 423 in the kinase activation loop as a critical determinant for the sensitivity to autoinhibition and enzymatic activity. Phosphorylation studies suggested that the stimulatory effect of both GTPase and sphingosine results in exposure of the activation loop, making it accessible for intermolecular phosphorylation.
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Affiliation(s)
- F T Zenke
- Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA
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41
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Gatti A, Huang Z, Tuazon PT, Traugh JA. Multisite autophosphorylation of p21-activated protein kinase gamma-PAK as a function of activation. J Biol Chem 1999; 274:8022-8. [PMID: 10075701 DOI: 10.1074/jbc.274.12.8022] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p21-activated protein kinase (PAK) is a family of serine/threonine kinases whose activity is stimulated by binding to small G-proteins such as Cdc42 and subsequent autophosphorylation. Focusing on the ubiquitous gamma-isoform of PAK in this study, baculovirus-infected insect cells were used to obtain recombinant gamma-PAK, while native gamma-PAK was isolated from rabbit reticulocytes. Two-dimensional gel electrophoresis of gamma-PAK followed by immunoblot analysis revealed a similar profile for native and recombinant gamma-PAK, both consisting of multiple protein spots. Following Cdc42-stimulated autophosphorylation, the two-dimensional profiles of native and recombinant gamma-PAK were characterized by a similar acidic shift, suggesting a common response to Cdc42. To understand the effect of differential phosphorylation on its activation status, gamma-PAK autophosphorylation was conducted in the presence or absence of activators such as Cdc42 and histone II-AS, followed by tryptic digestion and comparative two-dimensional phosphopeptide mapping. The major phosphopeptides were subjected to a combination of manual and automated amino acid sequencing. Overall, eight autophosphorylation sites were identified in Cdc42-activated gamma-PAK, six of which are in common with those previously reported in alpha-PAK, while Ser-19 and Ser-165 appear to be uniquely phosphorylated in the gamma-form. Further, the phosphorylation of Ser-141, Ser-165, and Thr-402 was found to correlate with gamma-PAK activation.
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Affiliation(s)
- A Gatti
- Department of Biochemistry, University of California, Riverside, California 92521, USA
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Chan WH, Yu JS, Yang SD. PAK2 is cleaved and activated during hyperosmotic shock-induced apoptosis via a caspase-dependent mechanism: evidence for the involvement of oxidative stress. J Cell Physiol 1999; 178:397-408. [PMID: 9989786 DOI: 10.1002/(sici)1097-4652(199903)178:3<397::aid-jcp14>3.0.co;2-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hyperosmotic shock elicits a stress response in mammalian cells and can lead to apoptotic cell death. In the present study, we report that hyperosmotic shock can induce activation of a 36 kDa kinase detected by an in-gel kinase assay in several cell types, including mouse Balb/c 3T3 fibroblasts, and human Hep 3B and A431 cells. This 36 kDa kinase can be recognized by an antibody against the C-terminal region of a family of p21Cdc42/Rac-activated kinases (PAKs) on immunoblot. Further studies with this antibody and a PAK2-specific antibody against the N-terminal region of PAK2 demonstrate that hyperosmotic shock can induce cleavage of PAK2 to generate a 36 kDa C-terminal catalytic fragment in cells. The cleavage and activation of PAK2 was found to be closely associated with both DNA fragmentation and activation of an ICE/CED-3 family cysteine protease termed caspase-3 in hyperosmotically shocked cells. Furthermore, pretreating the cells with two caspase inhibitors (Ac-DEVD-cho and Ac-YVAD-cmk) could inhibit both cleavage/activation of PAK2 and DNA fragmentation induced by hyperosmotic shock. Moreover, all these hyperosmotic shock-induced changes (i.e., activation of caspase-3, cleavage/activation of PAK2, and DNA fragmentation) in cells could be blocked by antioxidants such as ascorbic acid (vitamine C), alpha-tocopherol (vitamine E), dithiothreitol, beta-mercaptoethanol, and glutathione. Taken together, our results show that PAK2 is cleaved and activated via a caspase-dependent mechanism during hyperosmotic shock-induced apoptosis and suggest the involvement of antioxidant-preventable oxidative stress in inducing this process.
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Affiliation(s)
- W H Chan
- Department of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan, Republic of China
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Brzeska H, Young R, Knaus U, Korn ED. Myosin I heavy chain kinase: cloning of the full-length gene and acidic lipid-dependent activation by Rac and Cdc42. Proc Natl Acad Sci U S A 1999; 96:394-9. [PMID: 9892644 PMCID: PMC15147 DOI: 10.1073/pnas.96.2.394] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Acanthamoeba myosin I heavy chain kinase (MIHCK) phosphorylates the heavy chains of amoeba myosins I, increasing their actin-activated ATPase activities. The activity of MIHCK is increased by binding to acidic phospholipids or membranes and by autophosphorylation at multiple sites. Phosphorylation at a single site is necessary and sufficient for full activation of the expressed catalytic domain. The rate of autophosphorylation of native MIHCK is controlled by a region N-terminal to the catalytic domain. By its substrate specificity and the sequence of its C-terminal catalytic domain, MIHCK was identified as a p21-activated kinase (PAK). We have now cloned the full-length genomic DNA and cDNA of MIHCK and have shown it to contain the conserved p21-binding site common to many members of the PAK family. Like some mammalian PAKs, MIHCK is activated by Rac and Cdc42, and this activation is GTP-dependent and accompanied by autophosphorylation. In contrast to mammalian PAKs, activation of MIHCK by Rac and Cdc42 requires the presence of acidic lipids. Also unlike mammalian PAK, MIHCK is not activated by sphingosine or other non-negatively charged lipids. The acidic lipid-binding site is near the N terminus followed by the p21-binding region. The N-terminal regulatory domain of MIHCK contains alternating strongly positive and strongly negative regions. and the extremely Pro-rich middle region of MIHCK has a strongly acidic N-terminal segment and a strongly basic C-terminal segment. We propose that autophosphorylation activates MIHCK by neutralizing the basic segment of the Pro-rich region, thus unfolding the regulatory domain and abolishing its inhibition of the catalytic domain.
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Affiliation(s)
- H Brzeska
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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