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Somanath PR, Chernoff J, Cummings BS, Prasad SM, Homan HD. Targeting P21-Activated Kinase-1 for Metastatic Prostate Cancer. Cancers (Basel) 2023; 15:2236. [PMID: 37190165 PMCID: PMC10137274 DOI: 10.3390/cancers15082236] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/06/2023] [Accepted: 04/09/2023] [Indexed: 05/17/2023] Open
Abstract
Metastatic prostate cancer (mPCa) has limited therapeutic options and a high mortality rate. The p21-activated kinase (PAK) family of proteins is important in cell survival, proliferation, and motility in physiology, and pathologies such as infectious, inflammatory, vascular, and neurological diseases as well as cancers. Group-I PAKs (PAK1, PAK2, and PAK3) are involved in the regulation of actin dynamics and thus are integral for cell morphology, adhesion to the extracellular matrix, and cell motility. They also play prominent roles in cell survival and proliferation. These properties make group-I PAKs a potentially important target for cancer therapy. In contrast to normal prostate and prostatic epithelial cells, group-I PAKs are highly expressed in mPCA and PCa tissue. Importantly, the expression of group-I PAKs is proportional to the Gleason score of the patients. While several compounds have been identified that target group-I PAKs and these are active in cells and mice, and while some inhibitors have entered human trials, as of yet, none have been FDA-approved. Probable reasons for this lack of translation include issues related to selectivity, specificity, stability, and efficacy resulting in side effects and/or lack of efficacy. In the current review, we describe the pathophysiology and current treatment guidelines of PCa, present group-I PAKs as a potential druggable target to treat mPCa patients, and discuss the various ATP-competitive and allosteric inhibitors of PAKs. We also discuss the development and testing of a nanotechnology-based therapeutic formulation of group-I PAK inhibitors and its significant potential advantages as a novel, selective, stable, and efficacious mPCa therapeutic over other PCa therapeutics in the pipeline.
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Affiliation(s)
- Payaningal R. Somanath
- Department of Clinical & Administrative Pharmacy, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA
- MetasTx LLC, Basking Ridge, NJ 07920, USA
| | - Jonathan Chernoff
- MetasTx LLC, Basking Ridge, NJ 07920, USA
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Brian S. Cummings
- MetasTx LLC, Basking Ridge, NJ 07920, USA
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA
| | - Sandip M. Prasad
- Morristown Medical Center, Atlantic Health System, Morristown, NJ 07960, USA
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2
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Ravindran P, Püschel AW. An isoform-specific function of Cdc42 in regulating mammalian Exo70 during axon formation. Life Sci Alliance 2023; 6:6/3/e202201722. [PMID: 36543541 PMCID: PMC9772827 DOI: 10.26508/lsa.202201722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 12/09/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
The highly conserved GTPase Cdc42 is an essential regulator of cell polarity and promotes exocytosis through the exocyst complex in budding yeast and Drosophila In mammals, this function is performed by the closely related GTPase TC10, whereas mammalian Cdc42 does not interact with the exocyst. Axon formation is facilitated by the exocyst complex that tethers vesicles before their fusion to expand the plasma membrane. This function depends on the recruitment of the Exo70 subunit to the plasma membrane. Alternative splicing generates two Cdc42 isoforms that differ in their C-terminal 10 amino acids. Our results identify an isoform-specific function of Cdc42 in neurons. We show that the brain-specific Cdc42b isoform, in contrast to the ubiquitous isoform Cdc42u, can interact with Exo70. Inactivation of Arhgef7 or Cdc42b interferes with the exocytosis of post-Golgi vesicles in the growth cone. Cdc42b regulates exocytosis and axon formation downstream of its activator Arhgef7. Thus, the function of Cdc42 in regulating exocytosis is conserved in mammals but specific to one isoform.
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Affiliation(s)
- Priyadarshini Ravindran
- Institut für Integrative Zellbiologie und Physiologie, Westfälische Wilhelms-Universität, Münster, Germany
| | - Andreas W Püschel
- Institut für Integrative Zellbiologie und Physiologie, Westfälische Wilhelms-Universität, Münster, Germany .,Cells-in-Motion Interfaculty Center, University of Münster, Münster, Germany
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3
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Minor Kinases with Major Roles in Cytokinesis Regulation. Cells 2022; 11:cells11223639. [PMID: 36429067 PMCID: PMC9688779 DOI: 10.3390/cells11223639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/07/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022] Open
Abstract
Cytokinesis, the conclusive act of cell division, allows cytoplasmic organelles and chromosomes to be faithfully partitioned between two daughter cells. In animal organisms, its accurate regulation is a fundamental task for normal development and for preventing aneuploidy. Cytokinesis failures produce genetically unstable tetraploid cells and ultimately result in chromosome instability, a hallmark of cancer cells. In animal cells, the assembly and constriction of an actomyosin ring drive cleavage furrow ingression, resulting in the formation of a cytoplasmic intercellular bridge, which is severed during abscission, the final event of cytokinesis. Kinase-mediated phosphorylation is a crucial process to orchestrate the spatio-temporal regulation of the different stages of cytokinesis. Several kinases have been described in the literature, such as cyclin-dependent kinase, polo-like kinase 1, and Aurora B, regulating both furrow ingression and/or abscission. However, others exist, with well-established roles in cell-cycle progression but whose specific role in cytokinesis has been poorly investigated, leading to considering these kinases as "minor" actors in this process. Yet, they deserve additional attention, as they might disclose unexpected routes of cell division regulation. Here, we summarize the role of multifunctional kinases in cytokinesis with a special focus on those with a still scarcely defined function during cell cleavage. Moreover, we discuss their implication in cancer.
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Lakshmanan S, Rajendran R, Jayagandhi S, Rajendran R, Palanisamy T, Manimaran V, Janani Marianne A. Expression of Marker PAK1 in Sinonasal Polyposis. Indian J Otolaryngol Head Neck Surg 2022; 74:1694-1700. [PMID: 36452523 PMCID: PMC9702192 DOI: 10.1007/s12070-021-02822-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 08/15/2021] [Indexed: 10/20/2022] Open
Abstract
Introduction Chronic rhinosinusitis with nasal polyposis involves mucosal lining of nose and paranasal sinuses. Numerous studies studied the mechanism leading to sinonasal polyposis. We attempted study the inflammatory mechanisms responsible for the recruitment and activation of leukocytes. Aim To study and compare the expression of the immunohistochemistry marker PAK1 in sinonasal polyposis and normal nasal mucosa. Material and Methods Prospective observational study done by comparing two groups of 30 each with Group A comprises Sinonasal polyposis and Group B comprises normal nasal mucosa. The specimens were subjected to PAK1 immunohistochemical staining. Results Immunihistrochemical staining showed higher intensity stain in sinonasal polyp when compared to normal nasal mucosa. Conclusion The upregulation of PAK1 in sinonasal polyposis when compared to normal nasal mucosa may indicate an increased cellular proliferation and turnover in the background of chronic inflammation.
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Affiliation(s)
- Somu Lakshmanan
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
| | | | - Sathishkumar Jayagandhi
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
| | | | - Thirunavukarasu Palanisamy
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
| | - Vinoth Manimaran
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
| | - A. Janani Marianne
- Department of ENT and Head and Neck Surgery, Sri Ramachandra Medical College and Research Institute, Porur, Chennai, Tamil Nadu India
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5
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Li X, Li F. p21-Activated Kinase: Role in Gastrointestinal Cancer and Beyond. Cancers (Basel) 2022; 14:cancers14194736. [PMID: 36230657 PMCID: PMC9563254 DOI: 10.3390/cancers14194736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/23/2022] [Accepted: 09/23/2022] [Indexed: 11/23/2022] Open
Abstract
Simple Summary Gastrointestinal tumors are the most common tumors with a high mortality rate worldwide. Numerous protein kinases have been studied in anticipation of finding viable tumor therapeutic targets, including PAK. PAK is a serine/threonine kinase that plays an important role in the malignant phenotype of tumors. The function of PAK in tumors is highlighted in cell proliferation, survival, motility, tumor cell plasticity and the tumor microenvironment, therefore providing a new possible target for clinical tumor therapy. Based on the current research works of PAK, we summarize and analyze the PAK features and signaling pathways in cells, especially the role of PAK in gastrointestinal tumors, thereby hoping to provide a theoretical basis for both the future studies of PAK and potential tumor therapeutic targets. Abstract Gastrointestinal tumors are the most common tumors, and they are leading cause of cancer deaths worldwide, but their mechanisms are still unclear, which need to be clarified to discover therapeutic targets. p21-activating kinase (PAK), a serine/threonine kinase that is downstream of Rho GTPase, plays an important role in cellular signaling networks. According to the structural characteristics and activation mechanisms of them, PAKs are divided into two groups, both of which are involved in the biological processes that are critical to cells, including proliferation, migration, survival, transformation and metabolism. The biological functions of PAKs depend on a large number of interacting proteins and the signaling pathways they participate in. The role of PAKs in tumors is manifested in their abnormality and the consequential changes in the signaling pathways. Once they are overexpressed or overactivated, PAKs lead to tumorigenesis or a malignant phenotype, especially in tumor invasion and metastasis. Recently, the involvement of PAKs in cellular plasticity, stemness and the tumor microenvironment have attracted attention. Here, we summarize the biological characteristics and key signaling pathways of PAKs, and further analyze their mechanisms in gastrointestinal tumors and others, which will reveal new therapeutic targets and a theoretical basis for the clinical treatment of gastrointestinal cancer.
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Fa H, Xiao D, Chang W, Ding L, Yang L, Wang Y, Wang M, Wang J. MicroRNA-194-5p Attenuates Doxorubicin-Induced Cardiomyocyte Apoptosis and Endoplasmic Reticulum Stress by Targeting P21-Activated Kinase 2. Front Cardiovasc Med 2022; 9:815916. [PMID: 35321102 PMCID: PMC8934884 DOI: 10.3389/fcvm.2022.815916] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/10/2022] [Indexed: 12/15/2022] Open
Abstract
Objective Many studies have reported that microRNAs (miRs) are involved in the regulation of doxorubicin (DOX)-induced cardiotoxicity. MiR-194-5p has been reported significantly upregulated in patients with myocardial infarction; however, its role in myocardial diseases is still unclear. Various stimuluses can trigger the endoplasmic reticulum (ER) stress and it may activate the apoptosis signals eventually. This study aims to explore the regulatory role of miR-194-5p in DOX-induced ER stress and cardiomyocyte apoptosis. Methods H9c2 was treated with 2 μM DOX to induce apoptosis, which is to stimulate the DOX-induced cardiotoxicity model. The expression of miR-194-5p was detected by quantitative real-time PCR (qRT-PCR); the interaction between miR-194-5p and P21-activated kinase 2 (PAK2) was tested by dual luciferase reporter assay; terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and caspase-3/7 activity were used to assess apoptosis; trypan blue staining was applied to measure cell death; Western blotting was performed to detect protein expressions; and ER-related factors splicing X-box binding protein 1 (XBP1s) was detected by polyacrylamide gel electrophoresis and immunofluorescence to verify the activation of ER stress. Results MiR-194-5p was upregulated in cardiomyocytes and mouse heart tissue with DOX treatment, while the protein level of PAK2 was downregulated. PAK2 was predicted as the target of miR-194-5p; hence, dual luciferase reporter assay indicated that miR-194-5p directly interacted with PAK2 and inhibited its expression. TUNEL assay, caspase-3/7 activity test, and trypan blue stain results showed that either inhibition of miR-194-5p or overexpression of PAK2 reduced DOX-induced cardiomyocyte apoptosis. Silencing of miR-194-5p also improved DOX-induced cardiac dysfunction. In addition, DOX could induce ER stress in H9c2, which led to XBP1 and caspase-12 activation. The expression level of XBP1s with DOX treatment increased first then decreased. Overexpression of XBP1s suppressed DOX-induced caspase-3/7 activity elevation as well as the expression of cleaved caspase-12, which protected cardiomyocyte from apoptosis. Additionally, the activation of XBP1s was regulated by miR-194-5p and PAK2. Conclusion Our findings revealed that silencing miR-194-5p could alleviate DOX-induced cardiotoxicity via PAK2 and XBP1s in vitro and in vivo. Thus, the novel miR-194-5p/PAK2/XBP1s axis might be the potential prevention/treatment targets for cancer patients receiving DOX treatment.
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Affiliation(s)
- Hongge Fa
- School of Basic Medicine, Qingdao University, Qingdao, China
- Qingdao Women and Children’s Hospital, Qingdao University, Qingdao, China
| | - Dandan Xiao
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Wenguang Chang
- Institute for Translational Medicine, Qingdao University, Qingdao, China
| | - Lin Ding
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Lanting Yang
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Yu Wang
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Mengyu Wang
- School of Basic Medicine, Qingdao University, Qingdao, China
| | - Jianxun Wang
- School of Basic Medicine, Qingdao University, Qingdao, China
- *Correspondence: Jianxun Wang,
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7
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Lim SM, Cruz VE, Antoku S, Gundersen GG, Schwartz TU. Structures of FHOD1-Nesprin1/2 complexes reveal alternate binding modes for the FH3 domain of formins. Structure 2021; 29:540-552.e5. [PMID: 33472039 DOI: 10.1016/j.str.2020.12.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/23/2020] [Accepted: 12/21/2020] [Indexed: 12/12/2022]
Abstract
The nuclear position in eukaryotes is controlled by a nucleo-cytoskeletal network, critical in cell differentiation, division, and movement. Forces are transmitted through conserved Linker of Nucleoskeleton and Cytoskeleton (LINC) complexes that traverse the nuclear envelope and engage on either side of the membrane with diverse binding partners. Nesprin-2-giant (Nes2G), a LINC element in the outer nuclear membrane, connects to the actin directly as well as through FHOD1, a formin primarily involved in actin bundling. Here, we report the crystal structure of Nes2G bound to FHOD1 and show that the presumed G-binding domain of FHOD1 is rather a spectrin repeat (SR) binding enhancer for the neighboring FH3 domain. The structure reveals that SR binding by FHOD1 is likely not regulated by the diaphanous-autoregulatory domain helix of FHOD1. Finally, we establish that Nes1G also has one FHOD1 binding SR, indicating that these abundant, giant Nesprins have overlapping functions in actin-bundle recruitment for nuclear movement.
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Affiliation(s)
- Sing Mei Lim
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Victor E Cruz
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Susumu Antoku
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Thomas U Schwartz
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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8
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Kuroda K, Asano T, Horiguchi A, Ito K. Effect of increased expression of both ras-related C3 botulinum toxin substrate 1 and p21-activated kinase 1 in patients with N0M0 upper urinary tract urothelial carcinoma and cancer-free surgical margins. Jpn J Clin Oncol 2020; 50:465-472. [PMID: 32134451 DOI: 10.1093/jjco/hyz155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 09/06/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND As a member of the Rho small guanosine triphosphatase family, ras-related C3 botulinum toxin substrate 1 (RAC1) interacts with various specific effectors, and p21-activated kinase 1 (PAK1), which has a role in both carcinogenesis and cellular invasion, binds to RAC1, after which activated PAK1 regulates cellular functions. There have been few reports about the simultaneous analysis of RAC1 and its downstream effector PAK1 in upper urinary tract urothelial carcinoma (UTUC). We assessed the expressions of both RAC1 and PAK1 and evaluated their association with clinicopathological parameters. METHODS Immunohistochemical studies of RAC1 or PAK1 were performed with specimens from 104 patients with N0M0 UTUC and cancer-free surgical margins. Correlation of the positive expression of RAC1 or PAK1 or both with clinicopathological parameters was evaluated. RESULTS A hazard model showed that the presence of mixed histologic features and moderate or strong positive expression of both RAC1 and PAK1 were independent factors for shortened disease-specific survival time (Ps = 0.041 and 0.016, respectively), and another hazard model revealed that only moderate or strong positive expression of both RAC1 and PAK1 was an independent factor for shortened recurrence-free survival time in the multivariate analysis (P = 0.036). Neither moderate or strong positive expression of RAC1 alone nor moderate or strong positive expression of PAK1 alone was an independent factor for a worse rate of disease-specific or recurrence-free survival in multivariate analysis. CONCLUSIONS Patients with N0M0 UTUC, cancer-free surgical margins and moderate or strong positive expression of both RAC1 and PAK1 should be carefully monitored after surgery.
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Affiliation(s)
- Kenji Kuroda
- Department of Urology, National Defense Medical College, Tokorozawa, Saitama, Japan
| | - Takako Asano
- Department of Urology, National Defense Medical College, Tokorozawa, Saitama, Japan
| | - Akio Horiguchi
- Department of Urology, National Defense Medical College, Tokorozawa, Saitama, Japan
| | - Keiichi Ito
- Department of Urology, National Defense Medical College, Tokorozawa, Saitama, Japan
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9
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Zhang X, Xiao H, Zhang X, E Q, Gong X, Li T, Han Y, Ying X, Cherrington BD, Xu B, Liu X, Zhang X. Decreased microRNA-125b-5p disrupts follicle steroidogenesis through targeting PAK3/ERK1/2 signalling in mouse preantral follicles. Metabolism 2020; 107:154241. [PMID: 32304754 DOI: 10.1016/j.metabol.2020.154241] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 04/08/2020] [Accepted: 04/14/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND Hyperandrogenism is one of the major characteristics of polycystic ovary syndrome (PCOS). Abnormal miR-125b-5p expression has been documented in multiple diseases, but whether miR-125b-5p is associated with aberrant steroidogenesis in preantral follicles remains unknown. METHODS Steriod hormone concentrations and miR-125b-5p expression were measured in clinical serum samples from PCOS patients. Using a mouse preantral follicle culture model and a letrozole-induced PCOS mouse model, we investigated the mechanism underlying miR-125b-5p regulation of androgen and oestrogen secretion. RESULTS The decreased miR-125b-5p expression was observed in the sera from hyperandrogenic PCOS (HA-PCOS) patients. In mouse preantral follicles, inhibiting miR-125b-5p increased the expression of androgen synthesis-related genes and stimulated the secretion of testosterone, while simultaneously downregulating oestrogen synthesis-related genes and decreasing oestradiol release. Ectopically expressed miR-125b-5p reversed the effects on steroidogenesis-related gene expression and hormone release. Mechanistic studies identified Pak3 as a direct target of miR-125b-5p. Furthermore, inhibiting miR-125b-5p facilitated the activation of ERK1/2 in mouse preantral follicles, while inhibiting Pak3 abrogated this activating effect. These results were recapitulated in letrozole-induced PCOS mouse ovaries. Of note, inhibiting PAK3 antagonised the positive effect of miR-125b-5p siRNA on the expressions of androgen synthesis-related enzymes and testosterone secretion. Luteinizing hormone (LH) inhibited miR-125b-5p expression, and stimulated Pak3 expression. CONCLUSION High serum LH concentrations in PCOS patients repress miR-125b-5p expression, which further increases Pak3 expression, leading to activation of ERK1/2 signalling, thus stimulating the expression of androgen synthesis-related enzymes and testosterone secretion in HA-PCOS.
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Affiliation(s)
- Xiaoqian Zhang
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Hua Xiao
- Department of Obstetrics and Gynaecology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xueying Zhang
- Department of Obstetrics and Gynaecology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Qiukai E
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xuefeng Gong
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Tingting Li
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Yun Han
- Department of Obstetrics and Gynaecology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China; Department of Obstetrics and Gynaecology, Nantong First People's Hospital, Nantong, China
| | - Xiaoyan Ying
- Department of Obstetrics and Gynaecology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China; Department of Obstetrics and Gynaecology, the Affiliated Sir Run Run Hospital of Nanjing Medical University, Nanjing, China
| | - Brian D Cherrington
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Boqun Xu
- Department of Obstetrics and Gynaecology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China; Department of Obstetrics and Gynaecology, the Affiliated Sir Run Run Hospital of Nanjing Medical University, Nanjing, China.
| | - Xiaoqiu Liu
- Key Laboratory of Pathogen Biology of Jiangsu Province, Department of Microbiology, Nanjing Medical University, Nanjing, China.
| | - Xuesen Zhang
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China.
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10
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Joseph GA, Hung M, Goel AJ, Hong M, Rieder MK, Beckmann ND, Serasinghe MN, Chipuk JE, Devarakonda PM, Goldhamer DJ, Aldana-Hernandez P, Curtis J, Jacobs RL, Krauss RS. Late-onset megaconial myopathy in mice lacking group I Paks. Skelet Muscle 2019; 9:5. [PMID: 30791960 PMCID: PMC6383276 DOI: 10.1186/s13395-019-0191-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 02/12/2019] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Group I Paks are serine/threonine kinases that function as major effectors of the small GTPases Rac1 and Cdc42, and they regulate cytoskeletal dynamics, cell polarity, and transcription. We previously demonstrated that Pak1 and Pak2 function redundantly to promote skeletal myoblast differentiation during postnatal development and regeneration in mice. However, the roles of Pak1 and Pak2 in adult muscle homeostasis are unknown. Choline kinase β (Chk β) is important for adult muscle homeostasis, as autosomal recessive mutations in CHKβ are associated with two human muscle diseases, megaconial congenital muscular dystrophy and proximal myopathy with focal depletion of mitochondria. METHODS We analyzed mice conditionally lacking Pak1 and Pak2 in the skeletal muscle lineage (double knockout (dKO) mice) over 1 year of age. Muscle integrity in dKO mice was assessed with histological stains, immunofluorescence, electron microscopy, and western blotting. Assays for mitochondrial respiratory complex function were performed, as was mass spectrometric quantification of products of choline kinase. Mice and cultured myoblasts deficient for choline kinase β (Chk β) were analyzed for Pak1/2 phosphorylation. RESULTS dKO mice developed an age-related myopathy. By 10 months of age, dKO mouse muscles displayed centrally-nucleated myofibers, fibrosis, and signs of degeneration. Disease severity occurred in a rostrocaudal gradient, hindlimbs more strongly affected than forelimbs. A distinctive feature of this myopathy was elongated and branched intermyofibrillar (megaconial) mitochondria, accompanied by focal mitochondrial depletion in the central region of the fiber. dKO muscles showed reduced mitochondrial respiratory complex I and II activity. These phenotypes resemble those of rmd mice, which lack Chkβ and are a model for human diseases associated with CHKβ deficiency. Pak1/2 and Chkβ activities were not interdependent in mouse skeletal muscle, suggesting a more complex relationship in regulation of mitochondria and muscle homeostasis. CONCLUSIONS Conditional loss of Pak1 and Pak2 in mice resulted in an age-dependent myopathy with similarity to mice and humans with CHKβ deficiency. Protein kinases are major regulators of most biological processes but few have been implicated in muscle maintenance or disease. Pak1/Pak2 dKO mice offer new insights into these processes.
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Affiliation(s)
- Giselle A Joseph
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA.,Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA.,Present address: Novartis Institutes for BioMedical Research, 181 Massachusetts Ave, Cambridge, MA, 02139, USA
| | - Margaret Hung
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA.,Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA
| | - Aviva J Goel
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA.,Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA
| | - Mingi Hong
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA
| | - Marysia-Kolbe Rieder
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA
| | - Noam D Beckmann
- Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA.,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA
| | - Madhavika N Serasinghe
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Jerry E Chipuk
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Parvathi M Devarakonda
- Department of Molecular & Cell Biology, University of Connecticut, Storrs, CT, 06269, USA
| | - David J Goldhamer
- Department of Molecular & Cell Biology, University of Connecticut, Storrs, CT, 06269, USA
| | - Paulina Aldana-Hernandez
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Jonathan Curtis
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - René L Jacobs
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Robert S Krauss
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA. .,Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1020, New York, NY, 10029, USA.
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11
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Tam J, Hamza T, Ma B, Chen K, Beilhartz GL, Ravel J, Feng H, Melnyk RA. Host-targeted niclosamide inhibits C. difficile virulence and prevents disease in mice without disrupting the gut microbiota. Nat Commun 2018; 9:5233. [PMID: 30531960 PMCID: PMC6286312 DOI: 10.1038/s41467-018-07705-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/19/2018] [Indexed: 12/13/2022] Open
Abstract
Clostridium difficile is the leading cause of nosocomial diarrhea and colitis in the industrialized world. Disruption of the protective gut microbiota by antibiotics enables colonization by multidrug-resistant C. difficile, which secrete up to three different protein toxins that are responsible for the gastrointestinal sequelae. Oral agents that inhibit the damage induced by toxins, without altering the gut microbiota, are urgently needed to prevent primary disease and break the cycle of antibiotic-induced disease recurrence. Here, we show that the anthelmintic drug, niclosamide, inhibits the pathogenesis of all three toxins by targeting a host process required for entry into colonocytes by each toxin. In mice infected with an epidemic strain of C. difficile, expressing all three toxins, niclosamide reduced both primary disease and recurrence, without disrupting the diversity or composition of the gut microbiota. Given its excellent safety profile, niclosamide may address an important unmet need in preventing C. difficile primary and recurrent diseases. Clostridium difficile causes diarrhea and colitis by producing up to three different protein toxins. Here, Tam et al. show that an anthelmintic drug, niclosamide, inhibits the pathogenesis of all three toxins by targeting a host process required for toxin entry into host cells, without disrupting the gut microbiota.
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Affiliation(s)
- John Tam
- Molecular Medicine, Hospital for Sick Children, 686 Bay St., Toronto, ON, M5G 0A4, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Therwa Hamza
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD, 21201, USA
| | - Bing Ma
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kevin Chen
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD, 21201, USA
| | - Greg L Beilhartz
- Molecular Medicine, Hospital for Sick Children, 686 Bay St., Toronto, ON, M5G 0A4, Canada
| | - Jacques Ravel
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD, 21201, USA
| | - Roman A Melnyk
- Molecular Medicine, Hospital for Sick Children, 686 Bay St., Toronto, ON, M5G 0A4, Canada. .,Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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12
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López Tobón A, Suresh M, Jin J, Vitriolo A, Pietralla T, Tedford K, Bossenz M, Mahnken K, Kiefer F, Testa G, Fischer KD, Püschel AW. The guanine nucleotide exchange factor Arhgef7/βPix promotes axon formation upstream of TC10. Sci Rep 2018; 8:8811. [PMID: 29891904 PMCID: PMC5995858 DOI: 10.1038/s41598-018-27081-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/29/2018] [Indexed: 11/10/2022] Open
Abstract
The characteristic six layers of the mammalian neocortex develop sequentially as neurons are generated by neural progenitors and subsequently migrate past older neurons to their final position in the cortical plate. One of the earliest steps of neuronal differentiation is the formation of an axon. Small GTPases play essential roles during this process by regulating cytoskeletal dynamics and intracellular trafficking. While the function of GTPases has been studied extensively in cultured neurons and in vivo much less is known about their upstream regulators. Here we show that Arhgef7 (also called βPix or Cool1) is essential for axon formation during cortical development. The loss of Arhgef7 results in an extensive loss of axons in cultured neurons and in the developing cortex. Arhgef7 is a guanine-nucleotide exchange factor (GEF) for Cdc42, a GTPase that has a central role in directing the formation of axons during brain development. However, active Cdc42 was not able to rescue the knockdown of Arhgef7. We show that Arhgef7 interacts with the GTPase TC10 that is closely related to Cdc42. Expression of active TC10 can restore the ability to extend axons in Arhgef7-deficient neurons. Our results identify an essential role of Arhgef7 during neuronal development that promotes axon formation upstream of TC10.
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Affiliation(s)
- Alejandro López Tobón
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany.,Department of Oncology and Hemato-Oncology, University of Milan, Milan, 20122, Italy.,European Institute of Oncology, Via Adamello 16, 20139, Milan, Italy
| | - Megalakshmi Suresh
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany
| | - Jing Jin
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany
| | - Alessandro Vitriolo
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, 20122, Italy.,European Institute of Oncology, Via Adamello 16, 20139, Milan, Italy
| | - Thorben Pietralla
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany
| | - Kerry Tedford
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Leipziger Str. 44, 39120, Magdeburg, 39120, Germany
| | - Michael Bossenz
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Leipziger Str. 44, 39120, Magdeburg, 39120, Germany
| | - Kristina Mahnken
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany
| | - Friedemann Kiefer
- Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany.,Max-Planck-Institute for Molecular Biomedicine, Mammalian cell signaling laboratory, Röntgenstr. 20, D-48149, Münster, Germany.,European Institute for Molecular Imaging, Westfälische Wilhelms-Universität, Waldeyerstr. 15, D-48149, Münster, Germany
| | - Giuseppe Testa
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, 20122, Italy.,European Institute of Oncology, Via Adamello 16, 20139, Milan, Italy
| | - Klaus-Dieter Fischer
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Leipziger Str. 44, 39120, Magdeburg, 39120, Germany
| | - Andreas W Püschel
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany. .,Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany.
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13
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Lu H, Liu S, Zhang G, Wu B, Zhu Y, Frederick DT, Hu Y, Zhong W, Randell S, Sadek N, Zhang W, Chen G, Cheng C, Zeng J, Wu LW, Zhang J, Liu X, Xu W, Krepler C, Sproesser K, Xiao M, Miao B, Liu J, Song CD, Liu JY, Karakousis GC, Schuchter LM, Lu Y, Mills G, Cong Y, Chernoff J, Guo J, Boland GM, Sullivan RJ, Wei Z, Field J, Amaravadi RK, Flaherty KT, Herlyn M, Xu X, Guo W. PAK signalling drives acquired drug resistance to MAPK inhibitors in BRAF-mutant melanomas. Nature 2017; 550:133-136. [PMID: 28953887 PMCID: PMC5891348 DOI: 10.1038/nature24040] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 08/24/2017] [Indexed: 12/18/2022]
Abstract
Targeted BRAF inhibition (BRAFi) and combined BRAF and MEK inhibition (BRAFi and MEKi) therapies have markedly improved the clinical outcomes of patients with metastatic melanoma. Unfortunately, the efficacy of these treatments is often countered by the acquisition of drug resistance. Here we investigated the molecular mechanisms that underlie acquired resistance to BRAFi and to the combined therapy. Consistent with previous studies, we show that resistance to BRAFi is mediated by ERK pathway reactivation. Resistance to the combined therapy, however, is mediated by mechanisms independent of reactivation of ERK in many resistant cell lines and clinical samples. p21-activated kinases (PAKs) become activated in cells with acquired drug resistance and have a pivotal role in mediating resistance. Our screening, using a reverse-phase protein array, revealed distinct mechanisms by which PAKs mediate resistance to BRAFi and the combined therapy. In BRAFi-resistant cells, PAKs phosphorylate CRAF and MEK to reactivate ERK. In cells that are resistant to the combined therapy, PAKs regulate JNK and β-catenin phosphorylation and mTOR pathway activation, and inhibit apoptosis, thereby bypassing ERK. Together, our results provide insights into the molecular mechanisms underlying acquired drug resistance to current targeted therapies, and may help to direct novel drug development efforts to overcome acquired drug resistance.
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Affiliation(s)
- Hezhe Lu
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Shujing Liu
- Department of Pathology and Laboratory Medicine, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Gao Zhang
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Bin Wu
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Yueyao Zhu
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | | | - Yi Hu
- Department of Biology, Drexel University, Philadelphia, PA19104, U.S.A
| | - Wenqun Zhong
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Sergio Randell
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Norah Sadek
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Wei Zhang
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Gang Chen
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Chaoran Cheng
- Department of Computer Science, New Jersey Institute of Technology, Newark, NJ07102, U.S.A
| | - Jingwen Zeng
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Lawrence W. Wu
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Jie Zhang
- Department of Computer Science, New Jersey Institute of Technology, Newark, NJ07102, U.S.A
| | - Xiaoming Liu
- Department of Pathology and Laboratory Medicine, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Wei Xu
- Abramson Cancer Center and Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, U.S.A
| | - Clemens Krepler
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Katrin Sproesser
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Min Xiao
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Benchun Miao
- Massachusetts General Hospital Cancer Center, Boston, MA02114, U.S.A
| | - Jianglan Liu
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Claire D. Song
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Jephrey Y. Liu
- Abramson Cancer Center and Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, U.S.A
| | - Giorgos C. Karakousis
- Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA19104, U.S.A
| | - Lynn M. Schuchter
- Abramson Cancer Center and Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, U.S.A
| | - Yiling Lu
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX77054, USA
| | - Gordon Mills
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX77054, USA
| | - Yusheng Cong
- Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Jonathan Chernoff
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA19111, U.S.A
| | - Jun Guo
- Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Beijing, 100036, China
| | - Genevieve M. Boland
- Department of Surgical Oncology, Massachusetts General Hospital, Boston, Massachusetts 02114, U.S.A
| | - Ryan J. Sullivan
- Massachusetts General Hospital Cancer Center, Boston, MA02114, U.S.A
| | - Zhi Wei
- Department of Computer Science, New Jersey Institute of Technology, Newark, NJ07102, U.S.A
| | - Jeffrey Field
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA19104, U.S.A
| | - Ravi K. Amaravadi
- Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA19104, U.S.A
| | - Keith T. Flaherty
- Massachusetts General Hospital Cancer Center, Boston, MA02114, U.S.A
| | - Meenhard Herlyn
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, The Wistar Institute, Philadelphia, PA19104, U.S.A
| | - Xiaowei Xu
- Department of Pathology and Laboratory Medicine, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
| | - Wei Guo
- Department of Biology, the Hospital of the University of Pennsylvania, and Department of Dermatology, Perelman School of Medicine, University of Pennsylvania
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14
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Kumar R, Sanawar R, Li X, Li F. Structure, biochemistry, and biology of PAK kinases. Gene 2016; 605:20-31. [PMID: 28007610 DOI: 10.1016/j.gene.2016.12.014] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/24/2016] [Accepted: 12/14/2016] [Indexed: 02/07/2023]
Abstract
PAKs, p21-activated kinases, play central roles and act as converging junctions for discrete signals elicited on the cell surface and for a number of intracellular signaling cascades. PAKs phosphorylate a vast number of substrates and act by remodeling cytoskeleton, employing scaffolding, and relocating to distinct subcellular compartments. PAKs affect wide range of processes that are crucial to the cell from regulation of cell motility, survival, redox, metabolism, cell cycle, proliferation, transformation, stress, inflammation, to gene expression. Understandably, their dysregulation disrupts cellular homeostasis and severely impacts key cell functions, and many of those are implicated in a number of human diseases including cancers, neurological disorders, and cardiac disorders. Here we provide an overview of the members of the PAK family and their current status. We give special emphasis to PAK1 and PAK4, the prototypes of groups I and II, for their profound roles in cancer, the nervous system, and the heart. We also highlight other family members. We provide our perspective on the current advancements, their growing importance as strategic therapeutic targets, and our vision on the future of PAKs.
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Affiliation(s)
- Rakesh Kumar
- Department of Biochemistry and Molecular Medicine, School of Medicine and Health Sciences, George Washington University, Washington, DC 20037, USA; Cancer Biology Program, Rajiv Gandhi Center of Biotechnology, Thiruvananthapuram 695014, India.
| | - Rahul Sanawar
- Cancer Biology Program, Rajiv Gandhi Center of Biotechnology, Thiruvananthapuram 695014, India
| | - Xiaodong Li
- Department of Cell Biology, Key Laboratory of Medical Cell Biology, Chinese Ministry of Education, China Medical University, Shenyang 110122, China
| | - Feng Li
- Department of Cell Biology, Key Laboratory of Medical Cell Biology, Chinese Ministry of Education, China Medical University, Shenyang 110122, China.
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15
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The guanine nucleotide exchange factor Net1 facilitates the specification of dorsal cell fates in zebrafish embryos by promoting maternal β-catenin activation. Cell Res 2016; 27:202-225. [PMID: 27910850 DOI: 10.1038/cr.2016.141] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 09/18/2016] [Accepted: 09/27/2016] [Indexed: 12/14/2022] Open
Abstract
Wnt/β-catenin signaling is essential for the initiation of dorsal-ventral patterning during vertebrate embryogenesis. Maternal β-catenin accumulates in dorsal marginal nuclei during cleavage stages, but its critical target genes essential for dorsalization are silent until mid-blastula transition (MBT). Here, we find that zebrafish net1, a guanine nucleotide exchange factor, is specifically expressed in dorsal marginal blastomeres after MBT, and acts as a zygotic factor to promote the specification of dorsal cell fates. Loss- and gain-of-function experiments show that the GEF activity of Net1 is required for the activation of Wnt/β-catenin signaling in zebrafish embryos and mammalian cells. Net1 dissociates and activates PAK1 dimers, and PAK1 kinase activation causes phosphorylation of S675 of β-catenin after MBT, which ultimately leads to the transcription of downstream target genes. In summary, our results reveal that Net1-regulated β-catenin activation plays a crucial role in the dorsal axis formation during zebrafish development.
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16
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Sullivan CS, Kümper M, Temple BS, Maness PF. The Neural Cell Adhesion Molecule (NCAM) Promotes Clustering and Activation of EphA3 Receptors in GABAergic Interneurons to Induce Ras Homolog Gene Family, Member A (RhoA)/Rho-associated protein kinase (ROCK)-mediated Growth Cone Collapse. J Biol Chem 2016; 291:26262-26272. [PMID: 27803162 DOI: 10.1074/jbc.m116.760017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 10/24/2016] [Indexed: 02/03/2023] Open
Abstract
Establishment of a proper balance of excitatory and inhibitory connectivity is achieved during development of cortical networks and adjusted through synaptic plasticity. The neural cell adhesion molecule (NCAM) and the receptor tyrosine kinase EphA3 regulate the perisomatic synapse density of inhibitory GABAergic interneurons in the mouse frontal cortex through ephrin-A5-induced growth cone collapse. In this study, it was demonstrated that binding of NCAM and EphA3 occurred between the NCAM Ig2 domain and EphA3 cysteine-rich domain (CRD). The binding interface was further refined through molecular modeling and mutagenesis and shown to be comprised of complementary charged residues in the NCAM Ig2 domain (Arg-156 and Lys-162) and the EphA3 CRD (Glu-248 and Glu-264). Ephrin-A5 induced co-clustering of surface-bound NCAM and EphA3 in GABAergic cortical interneurons in culture. Receptor clustering was impaired by a charge reversal mutation that disrupted NCAM/EphA3 association, emphasizing the importance of the NCAM/EphA3 binding interface for cluster formation. NCAM enhanced ephrin-A5-induced EphA3 autophosphorylation and activation of RhoA GTPase, indicating a role for NCAM in activating EphA3 signaling through clustering. NCAM-mediated clustering of EphA3 was essential for ephrin-A5-induced growth cone collapse in cortical GABAergic interneurons, and RhoA and a principal effector, Rho-associated protein kinase, mediated the collapse response. This study delineates a mechanism in which NCAM promotes ephrin-A5-dependent clustering of EphA3 through interaction of the NCAM Ig2 domain and the EphA3 CRD, stimulating EphA3 autophosphorylation and RhoA signaling necessary for growth cone repulsion in GABAergic interneurons in vitro, which may extend to remodeling of axonal terminals of interneurons in vivo.
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Affiliation(s)
- Chelsea S Sullivan
- From the Department of Biochemistry and Biophysics, R. L. Juliano Structural Bioinformatics Core, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7264
| | - Maike Kümper
- From the Department of Biochemistry and Biophysics, R. L. Juliano Structural Bioinformatics Core, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7264
| | - Brenda S Temple
- From the Department of Biochemistry and Biophysics, R. L. Juliano Structural Bioinformatics Core, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7264
| | - Patricia F Maness
- From the Department of Biochemistry and Biophysics, R. L. Juliano Structural Bioinformatics Core, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7264
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17
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Chang JS, Su CY, Yu WH, Lee WJ, Liu YP, Lai TC, Jan YH, Yang YF, Shen CN, Shew JY, Lu J, Yang CJ, Huang MS, Lu PJ, Lin YF, Kuo ML, Hua KT, Hsiao M. GIT1 promotes lung cancer cell metastasis through modulating Rac1/Cdc42 activity and is associated with poor prognosis. Oncotarget 2016; 6:36278-91. [PMID: 26462147 PMCID: PMC4742177 DOI: 10.18632/oncotarget.5531] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 09/28/2015] [Indexed: 01/08/2023] Open
Abstract
G-protein-coupled receptor kinase interacting protein 1 (GIT1) is participated in cell movement activation, which is a fundamental process during tissue development and cancer progression. GIT1/PIX forming a functional protein complex that contributes to Rac1/Cdc42 activation, resulting in increasing cell mobility. Although the importance of Rac1/Cdc42 activation is well documented in cancer aggressiveness, the clinical importance of GIT1 remains largely unknown. Here, we investigated the clinical significance of GIT1 expression in non-small-cell lung cancer (NSCLC) and also verified the importance of GIT1-Rac1/Cdc42 axis in stimulating NSCLC cell mobility. The result indicated higher GIT1 expression patients had significantly poorer prognoses in disease-free survival (DFS) and overall survival (OS) compared with lower GIT1 expression patients. Higher GIT1 expression was an independent prognostic factor by multivariate analysis and associated with migration/invasion of NSCLC cells in transwell assay. In vivo studies indicated that GIT1 promotes metastasis of NSCLC cells. Finally, GIT1 was found to stimulate migration/invasion by altering the activity of Rac1/Cdc42 in NSCLC cells. Together, the GIT1 expression is associated with poor prognosis in patients with NSCLC. GIT1 is critical for the invasiveness of NSCLC cells through stimulating the activity of Rac1/Cdc42.
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Affiliation(s)
- Jeng-Shou Chang
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan.,Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Chia-Yi Su
- Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Wen-Hsuan Yu
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.,Graduate School of Biomedical Sciences, The University of Texas Houston Health Science Center, Houston, Texas, USA
| | - Wei-Jiunn Lee
- Department of Urology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.,Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Yu-Peng Liu
- Institute of Genomic Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Tsung-Ching Lai
- Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Yi-Hua Jan
- Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Yi-Fang Yang
- Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Chia-Ning Shen
- Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Jin-Yuh Shew
- Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Jean Lu
- Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Chih-Jen Yang
- Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ming-Shyan Huang
- Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Pei-Jung Lu
- Institute of Clinical Medicine, Medical College, National Cheng Kung University, Tainan, Taiwan
| | - Yuan-Feng Lin
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Min-Liang Kuo
- Institute of Biochemical Science, National Taiwan University College of Life Science, Taipei, Taiwan
| | - Kuo-Tai Hua
- Graduate Institute of Toxicology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Michael Hsiao
- Medical Biology, Genomics Research Center, Academia Sinica, Taipei, Taiwan
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18
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Guan L, Ma X, Zhang J, Liu JJ, Wang Y, Ding M. The Calponin Family Member CHDP-1 Interacts with Rac/CED-10 to Promote Cell Protrusions. PLoS Genet 2016; 12:e1006163. [PMID: 27415421 PMCID: PMC4944944 DOI: 10.1371/journal.pgen.1006163] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 06/10/2016] [Indexed: 02/02/2023] Open
Abstract
Eukaryotic cells extend a variety of surface protrusions to direct cell motility. Formation of protrusions is mediated by coordinated actions between the plasma membrane and the underlying actin cytoskeleton. Here, we found that the single calponin homology (CH) domain-containing protein CHDP-1 induces the formation of cell protrusions in C. elegans. CHDP-1 is anchored to the cortex through its amphipathic helix. CHDP-1 associates through its CH domain with the small GTPase Rac1/CED-10, which is a key regulator of the actin cytoskeleton. CHDP-1 preferentially binds to the GTP-bound active form of the CED-10 protein and preserves the membrane localization of GTP-CED-10. Hence, by coupling membrane expansion to Rac1-mediated actin dynamics, CHDP-1 promotes the formation of cellular protrusions in vivo.
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Affiliation(s)
- Liying Guan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Xuehua Ma
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jingyan Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jia-Jia Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai, China
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Mei Ding
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai, China
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Kumar R, Li DQ. PAKs in Human Cancer Progression: From Inception to Cancer Therapeutic to Future Oncobiology. Adv Cancer Res 2016; 130:137-209. [PMID: 27037753 DOI: 10.1016/bs.acr.2016.01.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Since the initial recognition of a mechanistic role of p21-activated kinase 1 (PAK1) in breast cancer invasion, PAK1 has emerged as one of the widely overexpressed or hyperactivated kinases in human cancer at-large, allowing the PAK family to make in-roads in cancer biology, tumorigenesis, and cancer therapeutics. Much of our current understanding of the PAK family in cancer progression relates to a central role of the PAK family in the integration of cancer-promoting signals from cell membrane receptors as well as function as a key nexus-modifier of complex, cytoplasmic signaling network. Another core aspect of PAK signaling that highlights its importance in cancer progression is through PAK's central role in the cross talk with signaling and interacting proteins, as well as PAK's position as a key player in the phosphorylation of effector substrates to engage downstream components that ultimately leads to the development cancerous phenotypes. Here we provide a comprehensive review of the recent advances in PAK cancer research and its downstream substrates in the context of invasion, nuclear signaling and localization, gene expression, and DNA damage response. We discuss how a deeper understanding of PAK1's pathobiology over the years has widened research interest to the PAK family and human cancer, and positioning the PAK family as a promising cancer therapeutic target either alone or in combination with other therapies. With many landmark findings and leaps in the progress of PAK cancer research since the infancy of this field nearly 20 years ago, we also discuss postulated advances in the coming decade as the PAK family continues to shape the future of oncobiology.
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Affiliation(s)
- R Kumar
- School of Medicine and Health Sciences, George Washington University, Washington, DC, United States; Rajiv Gandhi Center of Biotechnology, Thiruvananthapuram, India.
| | - D-Q Li
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China; Key Laboratory of Breast Cancer in Shanghai, Shanghai Medical College, Fudan University, Shanghai, China; Key Laboratory of Epigenetics in Shanghai, Shanghai Medical College, Fudan University, Shanghai, China.
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20
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Koval AB, Wuest WM. An optimized synthesis of the potent and selective Pak1 inhibitor FRAX-1036. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2015.12.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Bender KO, Garland M, Ferreyra JA, Hryckowian AJ, Child MA, Puri AW, Solow-Cordero DE, Higginbottom SK, Segal E, Banaei N, Shen A, Sonnenburg JL, Bogyo M. A small-molecule antivirulence agent for treating Clostridium difficile infection. Sci Transl Med 2015; 7:306ra148. [PMID: 26400909 DOI: 10.1126/scitranslmed.aac9103] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/04/2015] [Indexed: 12/22/2022]
Abstract
Clostridium difficile infection (CDI) is a worldwide health threat that is typically triggered by the use of broad-spectrum antibiotics, which disrupt the natural gut microbiota and allow this Gram-positive anaerobic pathogen to thrive. The increased incidence and severity of disease coupled with decreased response, high recurrence rates, and emergence of multiple antibiotic-resistant strains have created an urgent need for new therapies. We describe pharmacological targeting of the cysteine protease domain (CPD) within the C. difficile major virulence factor toxin B (TcdB). Through a targeted screen with an activity-based probe for this protease domain, we identified a number of potent CPD inhibitors, including one bioactive compound, ebselen, which is currently in human clinical trials for a clinically unrelated indication. This drug showed activity against both major virulence factors, TcdA and TcdB, in biochemical and cell-based studies. Treatment in a mouse model of CDI that closely resembles the human infection confirmed a therapeutic benefit in the form of reduced disease pathology in host tissues that correlated with inhibition of the release of the toxic glucosyltransferase domain (GTD). Our results show that this non-antibiotic drug can modulate the pathology of disease and therefore could potentially be developed as a therapeutic for the treatment of CDI.
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Affiliation(s)
- Kristina Oresic Bender
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA
| | - Megan Garland
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA
| | - Jessica A Ferreyra
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA
| | - Andrew J Hryckowian
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA
| | - Matthew A Child
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA
| | - Aaron W Puri
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA
| | - David E Solow-Cordero
- Stanford University High-Throughput Bioscience Center, 1291 Welch Road, Stanford, CA 94305-5174, USA
| | - Steven K Higginbottom
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA
| | - Ehud Segal
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA
| | - Niaz Banaei
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA. Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305-5107, USA
| | - Aimee Shen
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
| | - Justin L Sonnenburg
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA
| | - Matthew Bogyo
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA. Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA.
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22
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Huang HY, Zhang WT, Jiang WY, Chen SZ, Liu Y, Ge X, Li X, Dang YJ, Wen B, Liu XH, Lu HJ, Tang QQ. RhoGDIβ Inhibits Bone Morphogenetic Protein 4 (BMP4)-induced Adipocyte Lineage Commitment and Favors Smooth Muscle-like Cell Differentiation. J Biol Chem 2015; 290:11119-29. [PMID: 25778399 DOI: 10.1074/jbc.m114.608075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Indexed: 12/23/2022] Open
Abstract
The integration of signals involved in deciding the fate of mesenchymal stem cells is largely unknown. We used proteomics profiling to identify RhoGDIβ, an inhibitor of the small G-protein Rho family, as a component that regulates commitment of C3H10T1/2 mesenchymal stem cells to the adipocyte or smooth muscle cell lineage in response to bone morphogenetic protein 4 (BMP4). RhoGDIβ is notably down-regulated during BMP4-induced adipocytic lineage commitment of C3H10T1/2 mesenchymal stem cells, and this involves the cytoskeleton-associated protein lysyl oxidase. Excess RhoGDIβ completely prevents BMP4-induced commitment to the adipocyte lineage and simultaneously stimulates smooth muscle cell commitment by suppressing the activation of Rac1. Overexpression of RhoGDIβ induces stress fibers of F-actin by a process involving phosphomyosin light chain, indicating that cytoskeletal tension regulated by RhoGDIβ contributes to determining adipocyte versus myocyte commitment. Furthermore, the overexpression of RacV12 (constitutively active form of Rac1) totally rescues the inhibition of adipocyte commitment by RhoGDIβ, simultaneously preventing formation of the smooth muscle-like phenotype and disrupting the stress fibers in cells overexpressing RhoGDIβ. Collectively, these results indicate that RhoGDIβ functions as a novel BMP4 signaling target that regulates adipogenesis and myogensis.
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Affiliation(s)
- Hai-Yan Huang
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Wen-Ting Zhang
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Wen-Yan Jiang
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Su-Zhen Chen
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Yang Liu
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Xin Ge
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Xi Li
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Yong-Jun Dang
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Bo Wen
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
| | - Xiao-Hui Liu
- the Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, People's Republic of China
| | - Hao-Jie Lu
- the Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, People's Republic of China
| | - Qi-Qun Tang
- From the Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032 and
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23
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Tam J, Beilhartz GL, Auger A, Gupta P, Therien AG, Melnyk RA. Small molecule inhibitors of Clostridium difficile toxin B-induced cellular damage. ACTA ACUST UNITED AC 2015; 22:175-85. [PMID: 25619932 DOI: 10.1016/j.chembiol.2014.12.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 11/25/2014] [Accepted: 12/06/2014] [Indexed: 02/04/2023]
Abstract
Clostridium difficile causes life-threatening diarrhea through the actions of its homologous toxins TcdA and TcdB on human colonocytes. Therapeutic agents that block toxin-induced damage are urgently needed to prevent the harmful consequences of toxin action that are not addressed with current antibiotic-based treatments. Here, we developed an imaging-based phenotypic screen to identify small molecules that protected human cells from TcdB-induced cell rounding. A series of structurally diverse compounds with antitoxin activity were identified and found to act through one of a small subset of mechanisms, including direct binding and sequestration of TcdB, inhibition of endosomal maturation, and noncompetitive inhibition of the toxin glucosyltransferase activity. Distinct classes of inhibitors were used further to dissect the determinants of the toxin-mediated necrosis phenotype occurring at higher doses of toxin. These findings validate and inform novel targeting strategies for discovering small molecule agents to treat C. difficile infection.
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Affiliation(s)
- John Tam
- Molecular Structure & Function, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Greg L Beilhartz
- Molecular Structure & Function, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Anick Auger
- Molecular Structure & Function, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Pulkit Gupta
- Merck & Co. Inc., 2000 Galloping Hill Road, K15, Kenilworth, NJ 07033, USA
| | - Alex G Therien
- Merck & Co. Inc., 2000 Galloping Hill Road, K15, Kenilworth, NJ 07033, USA
| | - Roman A Melnyk
- Molecular Structure & Function, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
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24
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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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25
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Ribeiro SA, D'Ambrosio MV, Vale RD. Induction of focal adhesions and motility in Drosophila S2 cells. Mol Biol Cell 2014; 25:3861-9. [PMID: 25273555 PMCID: PMC4244196 DOI: 10.1091/mbc.e14-04-0863] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In this study, normally immotile S2 cells are engineered to induce the formation of focal adhesions and cell motility by the transfection of a single gene encoding an integrin subunit. It is demonstrated that the focal adhesions recruit expected components and exhibit mechanosensitive behavior on integrin-ligand substrates of different stiffnesses. Focal adhesions are dynamic structures that interact with the extracellular matrix on the cell exterior and actin filaments on the cell interior, enabling cells to adhere and crawl along surfaces. We describe a system for inducing the formation of focal adhesions in normally non–ECM-adherent, nonmotile Drosophila S2 cells. These focal adhesions contain the expected molecular markers such as talin, vinculin, and p130Cas, and they require talin for their formation. The S2 cells with induced focal adhesions also display a nonpolarized form of motility on vitronectin-coated substrates. Consistent with findings in mammalian cells, the degree of motility can be tuned by changing the stiffness of the substrate and was increased after the depletion of PAK3, a p21-activated kinase. A subset of nonmotile, nonpolarized cells also exhibited focal adhesions that rapidly assembled and disassembled around the cell perimeter. Such cooperative and dynamic fluctuations of focal adhesions were decreased by RNA interference (RNAi) depletion of myosin II and focal adhesion kinase, suggesting that this behavior requires force and focal adhesion maturation. These results demonstrate that S2 cells, a cell line that is well studied for cytoskeletal dynamics and readily amenable to protein manipulation by RNAi, can be used to study the assembly and dynamics of focal adhesions and mechanosensitive cell motility.
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Affiliation(s)
- Susana A Ribeiro
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158
| | - Michael V D'Ambrosio
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158
| | - Ronald D Vale
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158
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26
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Xu HG, Zhai YX, Chen J, Lu Y, Wang JW, Quan CS, Zhao RX, Xiao X, He Q, Werle KD, Kim HG, Lopez R, Cui R, Liang J, Li YL, Xu ZX. LKB1 reduces ROS-mediated cell damage via activation of p38. Oncogene 2014; 34:3848-59. [PMID: 25263448 PMCID: PMC4377312 DOI: 10.1038/onc.2014.315] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 08/05/2014] [Accepted: 08/06/2014] [Indexed: 12/27/2022]
Abstract
Liver kinase B1 (LKB1, also known as serine/threonine kinase 11, STK11) is a tumor suppressor mutated in Peutz-Jeghers syndrome and in a variety of sporadic cancers. Herein, we demonstrate that LKB1 controls the levels of intracellular reactive oxygen species (ROS) and protects the genome from oxidative damage. Cells lacking LKB1 exhibit markedly increased intracellular ROS levels, excessive oxidation of DNA, increased mutation rates, and accumulation of DNA damage, which are effectively prevented by ectopic expression of LKB1 and by incubation with antioxidant N-acetylcysteine (NAC). The role of LKB1 in suppressing ROS is independent of AMPK, a canonical substrate of LKB1. Instead, under the elevated ROS, LKB1 binds to and maintains the activity of cdc42-PAK1 (p21 activated kinase 1) complex, which triggers the activation of p38 and its downstream signaling targets, such as ATF-2, thereby enhancing the activity of SOD-2 and catalase, two antioxidant enzymes that protect the cells from ROS accumulation, DNA damage, and loss of viability. Our results provide a new paradigm for a non-canonical tumor suppressor function of LKB1 and highlight the importance of targeting ROS signaling as a potential therapeutic strategy for cancer cells lacking LKB1.
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Affiliation(s)
- H-G Xu
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Y-X Zhai
- Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - J Chen
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Y Lu
- Department of Endocrinology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - J-W Wang
- Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - C-S Quan
- Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - R-X Zhao
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - X Xiao
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Q He
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - K D Werle
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - H-G Kim
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - R Lopez
- Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - R Cui
- Department of Dermatology, Boston University, School of Medicine, Boston, MA, USA
| | - J Liang
- Department of Systems Biology, UT MD Anderson Cancer Center, Houston, TX, USA
| | - Y-L Li
- Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
| | - Z-X Xu
- 1] Division of Hematology and Oncology, Department of Medicine, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA [2] Key Laboratory of Pathobiology, Ministry of Education, Department of Pathology, Norman Bethune College of Medicine, Jilin University, Changchun, China
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27
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Abstract
p21-Activated protein kinases (PAKs) are centrally involved in a plethora of cellular processes and functions. Their function as effectors of small GTPases Rac1 and Cdc42 has been extensively studied during the past two decades, particularly in the realms of cell proliferation, apoptosis, and hence tumorigenesis, as well as cytoskeletal remodeling and related cellular events in health and disease. In recent years, a large number of studies have shed light onto the fundamental role of group I PAKs, most notably PAK1, in metabolic homeostasis. In skeletal muscle, PAK1 was shown to mediate the function of insulin on stimulating GLUT4 translocation and glucose uptake, while in pancreatic β-cells, PAK1 participates in insulin granule localization and vesicle release. Furthermore, we demonstrated that PAK1 mediates the cross talk between insulin and Wnt/β-catenin signaling pathways and hence regulates gut proglucagon gene expression and the production of the incretin hormone glucagon-like peptide-1 (GLP-1). The utilization of chemical inhibitors of PAK and the characterization of Pak1(-/-) mice enabled us to gain mechanistic insights as well as to assess the overall contribution of PAKs in metabolic homeostasis. This review summarizes our current understanding of PAKs, with an emphasis on the emerging roles of PAK1 in glucose homeostasis.
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28
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Dandekar SN, Park JS, Peng GE, Onuffer JJ, Lim WA, Weiner OD. Actin dynamics rapidly reset chemoattractant receptor sensitivity following adaptation in neutrophils. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130008. [PMID: 24062580 DOI: 10.1098/rstb.2013.0008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Neutrophils are cells of the innate immune system that hunt and kill pathogens using directed migration. This process, known as chemotaxis, requires the regulation of actin polymerization downstream of chemoattractant receptors. Reciprocal interactions between actin and intracellular signals are thought to underlie many of the sophisticated signal processing capabilities of the chemotactic cascade including adaptation, amplification and long-range inhibition. However, with existing tools, it has been difficult to discern actin's role in these processes. Most studies investigating the role of the actin cytoskeleton have primarily relied on actin-depolymerizing agents, which not only block new actin polymerization but also destroy the existing cytoskeleton. We recently developed a combination of pharmacological inhibitors that stabilizes the existing actin cytoskeleton by inhibiting actin polymerization, depolymerization and myosin-based rearrangements; we refer to these processes collectively as actin dynamics. Here, we investigated how actin dynamics influence multiple signalling responses (PI3K lipid products, calcium and Pak phosphorylation) following acute agonist addition or during desensitization. We find that stabilized actin polymer extends the period of receptor desensitization following agonist binding and that actin dynamics rapidly reset receptors from this desensitized state. Spatial differences in actin dynamics may underlie front/back differences in agonist sensitivity in neutrophils.
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Affiliation(s)
- Sheel N Dandekar
- Department of Biophysics, Genentech Hall, University of California, , 600 16th Street, San Francisco, CA 94158, USA
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29
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Rao JS, Gujrati M, Chetty C. Tumor-associated soluble uPAR-directed endothelial cell motility and tumor angiogenesis. Oncogenesis 2013; 2:e53. [PMID: 23797476 PMCID: PMC3740303 DOI: 10.1038/oncsis.2013.19] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The expression of urokinase-type plasminogen activator (uPA) receptor (uPAR) correlates with the malignant phenotype of various cancers. The soluble form of uPAR (s-uPAR) is present in the circulation of cancer patients, but the role of s-uPAR in endothelial cell migration is poorly understood. Therefore, we examined the role of tumor-associated s-uPAR on endothelial cell motility and angiogenesis. Here, we present evidence that tumor-associated s-uPAR augments the migration of human umbilical vein endothelial cells (HUVECs). When grown on tumor-conditioned medium, the membrane fraction of HUVECs had increased localization of s-uPAR onto its cell membrane. Colocalization studies for GM1 ganglioside receptor and uPAR further demonstrated s-uPAR recruitment onto lipid rafts of HUVECs. Immunoblot analysis for uPAR in lipid raft fractions confirmed s-uPAR recruiting onto HUVECs' membrane. Further, s-uPAR induced Rac1-mediated cell migration while either function-blocking uPAR antibodies or dominant-negative mutant Rac1 expression in HUVECs-mitigated s-uPAR-enhanced cell migration. In addition, orthotopic implantation of uPAR-overexpressing cells resulted in a significant increase in circulating s-uPAR in blood serum and invasive nature of tumor and tumor vasculature in mice. Collectively, this data provide insight into tumor-associated s-uPAR-directed migration of endothelial cells and its subsequent influence on tumor angiogenesis.
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Affiliation(s)
- J S Rao
- 1] Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA [2] Department of Neurosurgery, University of Illinois College of Medicine at Peoria, Peoria, IL, USA
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30
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Leoni G, Alam A, Neumann PA, Lambeth JD, Cheng G, McCoy J, Hilgarth RS, Kundu K, Murthy N, Kusters D, Reutelingsperger C, Perretti M, Parkos CA, Neish AS, Nusrat A. Annexin A1, formyl peptide receptor, and NOX1 orchestrate epithelial repair. J Clin Invest 2012; 123:443-54. [PMID: 23241962 DOI: 10.1172/jci65831] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/18/2012] [Indexed: 01/05/2023] Open
Abstract
N-formyl peptide receptors (FPRs) are critical regulators of host defense in phagocytes and are also expressed in epithelia. FPR signaling and function have been extensively studied in phagocytes, yet their functional biology in epithelia is poorly understood. We describe a novel intestinal epithelial FPR signaling pathway that is activated by an endogenous FPR ligand, annexin A1 (ANXA1), and its cleavage product Ac2-26, which mediate activation of ROS by an epithelial NADPH oxidase, NOX1. We show that epithelial cell migration was regulated by this signaling cascade through oxidative inactivation of the regulatory phosphatases PTEN and PTP-PEST, with consequent activation of focal adhesion kinase (FAK) and paxillin. In vivo studies using intestinal epithelial specific Nox1(-/-IEC) and AnxA1(-/-) mice demonstrated defects in intestinal mucosal wound repair, while systemic administration of ANXA1 promoted wound recovery in a NOX1-dependent fashion. Additionally, increased ANXA1 expression was observed in the intestinal epithelium and infiltrating leukocytes in the mucosa of ulcerative colitis patients compared with normal intestinal mucosa. Our findings delineate a novel epithelial FPR1/NOX1-dependent redox signaling pathway that promotes mucosal wound repair.
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Affiliation(s)
- Giovanna Leoni
- Epithelial Pathobiology and Mucosal Inflammation Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
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31
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Staser K, Shew MA, Michels EG, Mwanthi MM, Yang FC, Clapp DW, Park SJ. A Pak1-PP2A-ERM signaling axis mediates F-actin rearrangement and degranulation in mast cells. Exp Hematol 2012; 41:56-66.e2. [PMID: 23063725 DOI: 10.1016/j.exphem.2012.10.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 10/01/2012] [Accepted: 10/06/2012] [Indexed: 01/12/2023]
Abstract
Mast cells coordinate allergy and allergic asthma and are crucial cellular targets in therapeutic approaches to inflammatory disease. Allergens cross-link immunoglobulin E bound at high-affinity receptors on the mast cell's surface, causing release of preformed cytoplasmic granules containing inflammatory molecules, including histamine, a principal effector of fatal septic shock. Both p21 activated kinase 1 (Pak1) and protein phosphatase 2A (PP2A) modulate mast cell degranulation, but the molecular mechanisms underpinning these observations and their potential interactions in common or disparate pathways are unknown. In this study, we use genetic and other approaches to show that Pak1's kinase-dependent interaction with PP2A potentiates PP2A's subunit assembly and activation. PP2A then dephosphorylates threonine 567 of Ezrin/Radixin/Moesin (ERM) molecules that have been shown to couple F-actin to the plasma membrane in other cell systems. In our study, the activity of this Pak1-PP2A-ERM axis correlates with impaired systemic histamine release in Pak1(-/-) mice and defective F-actin rearrangement and impaired degranulation in Ezrin disrupted (Mx1Cre(+)Ezrin(flox/flox)) primary mast cells. This heretofore unknown mechanism of mast cell degranulation provides novel therapeutic targets in allergy and asthma and may inform studies of kinase regulation of cytoskeletal dynamics in other cell lineages.
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Affiliation(s)
- Karl Staser
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
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PAK1 kinase promotes cell motility and invasiveness through CRK-II serine phosphorylation in non-small cell lung cancer cells. PLoS One 2012; 7:e42012. [PMID: 22848689 PMCID: PMC3407072 DOI: 10.1371/journal.pone.0042012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 06/29/2012] [Indexed: 12/20/2022] Open
Abstract
The role of c-Crk (CRK) in promoting metastasis is well described however the role of CRK phosphorylation and the corresponding signaling events are not well explained. We have observed CRK-II serine 41 phosphorylation is inversely correlated with p120-catenin and E-cadherin expressions in non-small cell lung cancer (NSCLC) cells. Therefore, we investigated the role of CRK-II serine 41 phosphorylation in the down-regulation of p120-catenin, cell motility and cell invasiveness in NSCLC cells. For this purpose, we expressed phosphomimetic and phosphodeficient CRK-II serine 41 mutants in NSCLC cells. NSCLC cells expressing phosphomimetic CRK-II seine 41 mutant showed lower p120-catenin level while CRK-II seine 41 phosphodeficient mutant expression resulted in higher p120-catenin. In addition, A549 cells expressing CRK-II serine 41 phosphomimetic mutant demonstrated more aggressive behavior in wound healing and invasion assays and, on the contrary, expression of phosphodeficient CRK-II serine 41 mutant in A549 cells resulted in reduced cell motility and invasiveness. We also provide evidence that PAK1 mediates CRK-II serine 41 phosphorylation. RNAi mediated silencing of PAK1 increased p120-catenin level in A549 and H157 cells. Furthermore, PAK1 silencing decreased cell motility and invasiveness in A549 cells. These effects were abrogated in A549 cells expressing phosphomimetic CRK-II serine 41. In summary, these data provide evidence for the role of PAK1 in the promotion of cell motility, cell invasiveness and the down regulation of p120-catenin through CRK serine 41 phosphorylation in NSCLC cells.
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Faust D, Schmitt C, Oesch F, Oesch-Bartlomowicz B, Schreck I, Weiss C, Dietrich C. Differential p38-dependent signalling in response to cellular stress and mitogenic stimulation in fibroblasts. Cell Commun Signal 2012; 10:6. [PMID: 22404972 PMCID: PMC3352310 DOI: 10.1186/1478-811x-10-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 03/09/2012] [Indexed: 01/07/2023] Open
Abstract
p38 MAP kinase is known to be activated by cellular stress finally leading to cell cycle arrest or apoptosis. Furthermore, a tumour suppressor role of p38 MAPK has been proposed. In contrast, a requirement of p38 for proliferation has also been described. To clarify this paradox, we investigated stress- and mitogen-induced p38 signalling in the same cell type using fibroblasts. We demonstrate that - in the same cell line - p38 is activated by mitogens or cellular stress, but p38-dependent signalling is different. Exposure to cellular stress, such as anisomycin, leads to a strong and persistent p38 activation independent of GTPases. As a result, MK2 and downstream the transcription factor CREB are phosphorylated. In contrast, mitogenic stimulation results in a weaker and transient p38 activation, which upstream involves small GTPases and is required for cyclin D1 induction. Consequently, the retinoblastoma protein is phosphorylated and allows G1/S transition. Our data suggest a dual role of p38 and indicate that the level and/or duration of p38 activation determines the cellular response, i.e either proliferation or cell cycle arrest.
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Affiliation(s)
- Dagmar Faust
- Institute of Toxicology, Medical Center of the Johannes Gutenberg-University, Obere Zahlbacherstr, 67, 55131 Mainz, Germany.
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Abstract
EHDs [EH (Eps15 homology)-domain-containing proteins] participate in different stages of endocytosis. EHD2 is a plasma-membrane-associated EHD which regulates trafficking from the plasma membrane and recycling. EHD2 has a role in nucleotide-dependent membrane remodelling and its ATP-binding domain is involved in dimerization, which creates a membrane-binding region. Nucleotide binding is important for association of EHD2 with the plasma membrane, since a nucleotide-free mutant (EHD2 T72A) failed to associate. To elucidate the possible function of EHD2 during endocytic trafficking, we attempted to unravel proteins that interact with EHD2, using the yeast two-hybrid system. A novel interaction was found between EHD2 and Nek3 [NIMA (never in mitosis in Aspergillus nidulans)-related kinase 3], a serine/threonine kinase. EHD2 was also found in association with Vav1, a Nek3-regulated GEF (guanine-nucleotide-exchange factor) for Rho GTPases. Since Vav1 regulates Rac1 activity and promotes actin polymerization, the impact of overexpression of EHD2 on Rac1 activity was tested. The results indicated that wt (wild-type) EHD2, but not its P-loop mutants, reduced Rac1 activity. The inhibitory effect of EHD2 overexpression was partially rescued by co-expression of Rac1 as measured using a cholera toxin trafficking assay. The results of the present study strongly indicate that EHD2 regulates trafficking from the plasma membrane by controlling Rac1 activity.
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Nekrasova T, Minden A. PAK4 is required for regulation of the cell-cycle regulatory protein p21, and for control of cell-cycle progression. J Cell Biochem 2011; 112:1795-806. [PMID: 21381077 DOI: 10.1002/jcb.23092] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The serine/threonine kinase PAK4 regulates cytoskeletal architecture, and controls cell proliferation and survival. In most adult tissues PAK4 is expressed at low levels, but overexpression of PAK4 is associated with uncontrolled proliferation, inappropriate cell survival, and oncogenic transformation. Here we have studied for the first time, the role for PAK4 in the cell cycle. We found that PAK4 levels peak dramatically but transiently in the early part of G1 phase. Deletion of Pak4 was also associated with an increase in p21 levels, and PAK4 was required for normal p21 degradation. In serum-starved cells, the absence of PAK4 led to a reduction in the amount of cells in G1, and an increase in the amount of cells in G2/M phase. We propose that the transient increase in PAK4 levels at early G1 reduces p21 levels, thereby abrogating the activity of CDK4/CDK6 kinases, and allowing cells to proceed with the cell cycle in a precisely coordinated way.
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Affiliation(s)
- Tanya Nekrasova
- Susan Lehman Cullman Laboratory for Cancer Research, Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey Piscataway, New Jersey 08854, USA
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Thévenot E, Moreau AW, Rousseau V, Combeau G, Domenichini F, Jacquet C, Goupille O, Amar M, Kreis P, Fossier P, Barnier JV. p21-Activated kinase 3 (PAK3) protein regulates synaptic transmission through its interaction with the Nck2/Grb4 protein adaptor. J Biol Chem 2011; 286:40044-59. [PMID: 21949127 DOI: 10.1074/jbc.m111.262246] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in the p21-activated kinase 3 gene (pak3) are responsible for nonsyndromic forms of mental retardation. Expression of mutated PAK3 proteins in hippocampal neurons induces abnormal dendritic spine morphology and long term potentiation anomalies, whereas pak3 gene invalidation leads to cognitive impairments. How PAK3 regulates synaptic plasticity is still largely unknown. To better understand how PAK3 affects neuronal synaptic plasticity, we focused on its interaction with the Nck adaptors that play a crucial role in PAK signaling. We report here that PAK3 interacts preferentially with Nck2/Grb4 in brain extracts and in transfected cells. This interaction is independent of PAK3 kinase activity. Selective uncoupling of the Nck2 interactions in acute cortical slices using an interfering peptide leads to a rapid increase in evoked transmission to pyramidal neurons. The P12A mutation in the PAK3 protein strongly decreases the interaction with Nck2 but only slightly with Nck1. In transfected hippocampal cultures, expression of the P12A-mutated protein has no effect on spine morphogenesis or synaptic density. The PAK3-P12A mutant does not affect synaptic transmission, whereas the expression of the wild-type PAK3 protein decreases the amplitude of spontaneous miniature excitatory currents. Altogether, these data show that PAK3 down-regulates synaptic transmission through its interaction with Nck2.
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Affiliation(s)
- Emmanuel Thévenot
- CNRS, Institut de Neurobiologie Alfred Fessard, Laboratoire de Neurobiologie Cellulaire et Moléculaire, 91190 Gif sur Yvette, France
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Zhou L, Zhang Z, Zheng Y, Zhu Y, Wei Z, Xu H, Tang Q, Kong X, Hu L. SKAP2, a novel target of HSF4b, associates with NCK2/F-actin at membrane ruffles and regulates actin reorganization in lens cell. J Cell Mol Med 2011; 15:783-95. [PMID: 20219016 PMCID: PMC3922667 DOI: 10.1111/j.1582-4934.2010.01048.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
In addition to roles in stress response, heat shock factors (HSFs) play crucial roles in differentiation and development. Heat shock transcription factor 4 (HSF4) deficiency leads to defect in lens epithelial cell (LEC) differentiation and cataract formation. However, the mechanism remains obscure. Here, we identified Src kinase-associated phosphoprotein 2 (SKAP2) as a downstream target of HSF4b and it was highly expressed at the anterior tip of lens elongating fibre cells in vivo. The HSF4-deficient lenses showed reduced SKAP2 expression and defects in actin reorganization. The disassembly of stress fibres and formation of cortical actin fibres are critical for the initiation of LEC differentiation. SKAP2 localized at actin-rich ruffles in human LECs (SRA01/04 cells) and knockdown SKAP2 using RNA interference impaired the disassembly of cellular stress fibres in response to fibroblast growth factor (FGF)-b. Overexpression of SKAP2, but not the N-terminal deletion mutant of SKAP2, induced the actin remodelling. We further found that SKAP2 interacted with the SH2 domain of non-catalytic region of tyrosine kinase adaptor protein 2 (NCK2) via its N-terminus. The complex of SKAP2-NCK2-F-actin accumulated at the leading edge of the lamellipodium, where FGF receptors and focal adhesion were also recruited. These results revealed an essential role for HSF4-mediated SKAP2 expression in the regulation of actin reorganization during lens differentiation, likely through a mechanism that SKAP2 anchors the complex of NCK2/focal adhesion to FGF receptors at the lamellipodium in lens epithelial cells.
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Affiliation(s)
- Li Zhou
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) & Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, People's Republic of China
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Marlin JW, Chang YWE, Ober M, Handy A, Xu W, Jakobi R. Functional PAK-2 knockout and replacement with a caspase cleavage-deficient mutant in mice reveals differential requirements of full-length PAK-2 and caspase-activated PAK-2p34. Mamm Genome 2011; 22:306-17. [PMID: 21499899 DOI: 10.1007/s00335-011-9326-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2011] [Accepted: 03/23/2011] [Indexed: 11/26/2022]
Abstract
p21-Activated protein kinase 2 (PAK-2) has both anti- and pro-apoptotic functions depending on its mechanism of activation. Activation of full-length PAK-2 by the monomeric GTPases Cdc42 or Rac stimulates cell survival, whereas caspase activation of PAK-2 to the PAK-2p34 fragment is involved in the apoptotic response. In this study we use functional knockout of PAK-2 and gene replacement with the caspase cleavage-deficient PAK-2D212N mutant to differentiate the biological functions of full-length PAK-2 and caspase-activated PAK-2p34. Knockout of PAK-2 results in embryonic lethality at early stages before organ development, whereas replacement with the caspase cleavage-deficient PAK-2D212N results in viable and healthy mice, indicating that early embryonic lethality is caused by deficiency of full-length PAK-2 rather than lack of caspase activation to the PAK-2p34 fragment. However, deficiency of caspase activation of PAK-2 decreased spontaneous cell death of primary mouse embryonic fibroblasts and increased cell growth at high cell density. In contrast, stress-induced cell death by treatment with the anti-cancer drug cisplatin was not reduced by deficiency of caspase activation of PAK-2, but switched from an apoptotic to a nonapoptotic, caspase-independent mechanism. Homozygous PAK-2D212N primary mouse embryonic fibroblasts that lack the ability to generate the proapoptotic PAK-2p34 show less activation of the effector caspase 3, 6, and 7, indicating that caspase activation of PAK-2 amplifies the apoptotic response through a positive feedback loop resulting in more activation of effector caspases.
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Affiliation(s)
- Jerry W Marlin
- Department of Biochemistry, Kansas City University of Medicine and Biosciences, 1750 Independence Avenue, Kansas City, MO 64106, USA
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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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Kichina JV, Goc A, Al-Husein B, Somanath PR, Kandel ES. PAK1 as a therapeutic target. Expert Opin Ther Targets 2010; 14:703-25. [PMID: 20507214 DOI: 10.1517/14728222.2010.492779] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
IMPORTANCE OF THE FIELD P21-activated kinases (PAKs) are involved in multiple signal transduction pathways in mammalian cells. PAKs, and PAK1 in particular, play a role in such disorders as cancer, mental retardation and allergy. Cell motility, survival and proliferation, the organization and function of cytoskeleton and extracellular matrix, transcription and translation are among the processes affected by PAK1. AREAS COVERED IN THIS REVIEW We discuss the mechanisms that control PAK1 activity, its involvement in physiological and pathophysiological processes, the benefits and the drawbacks of the current tools to regulate PAK1 activity, the evidence that suggests PAK1 as a therapeutic target and the likely directions of future research. WHAT THE READER WILL GAIN The reader will gain a better knowledge and understanding of the areas described above. TAKE HOME MESSAGE PAK1 is a promising therapeutic target in cancer and allergen-induced disorders. Its suitability as a target in vascular, neurological and infectious diseases remains ambiguous. Further advancement of this field requires progress on such issues as the development of specific and clinically acceptable inhibitors, the choice between targeting one or multiple PAK isoforms, elucidation of the individual roles of PAK1 targets and the mechanisms that may circumvent inhibition of PAK1.
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Affiliation(s)
- Julia V Kichina
- Roswell Park Cancer Institute, Department of Cell Stress Biology, Elm and Carlton Streets, Buffalo, NY 14263, USA
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Liu RX, Wang WQ, Ye L, Bi YF, Fang H, Cui B, Zhou WW, Dai M, Zhang J, Li XY, Ning G. p21-activated kinase 3 is overexpressed in thymic neuroendocrine tumors (carcinoids) with ectopic ACTH syndrome and participates in cell migration. Endocrine 2010; 38:38-47. [PMID: 20960100 DOI: 10.1007/s12020-010-9324-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 03/10/2010] [Indexed: 01/23/2023]
Abstract
Thymic carcinoid is an important component of the tumor spectrum causing Ectopic ACTH Syndrome (EAS) and usually carries a poor prognosis. Efforts have been focused on exploring the mechanism of the excessive ACTH production in non-pituitary tumors, whereas few studies have reported the molecular events underlying the tumor progression. In this study, seven patients with ACTH producing thymic carcinoids were enrolled. Of note is that five of them showed either lymph node metastasis, local invasion or distant metastasis. By using cDNA profiling approach, we evaluated the expression of cell adhesion pathway genes and found a remarkable overexpression of p21-activated kinase 3 (PAK3) in all thymic carcinoids which was further confirmed at both transcriptional and translational level. RAC1, an upstream activator of PAK3, was also overexpressed in thymic carcinoids. Overexpression of PAK3 in NIH3T3 cell enhanced cell migration and invasion. Importantly, we observed c-Jun NH(2)-terminal kinase (JNK) was activated in PAK3 transfected cells, and inhibition of JNK activity by SP600125, a JNK pathway inhibitor, abolished PAK3 mediated cell migration. Activation of JNK pathway was also detected in thymic carcinoid with high level of PAK3 expression. Our findings suggested a potential role of PAK3 in the progression of ACTH-producing thymic carcinoid.
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Affiliation(s)
- Rui-xin Liu
- Shanghai Key Laboratory for Endocrine Tumors, Department of Endocrinology and Metabolism, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China
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Park ER, Pullikuth AK, Bailey EM, Mercante DE, Catling AD. Differential requirement for MEK Partner 1 in DU145 prostate cancer cell migration. Cell Commun Signal 2009; 7:26. [PMID: 19930650 PMCID: PMC2788567 DOI: 10.1186/1478-811x-7-26] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 11/23/2009] [Indexed: 11/10/2022] Open
Abstract
ERK signaling regulates focal adhesion disassembly during cell movement, and increased ERK signaling frequently contributes to enhanced motility of human tumor cells. We previously found that the ERK scaffold MEK Partner 1 (MP1) is required for focal adhesion disassembly in fibroblasts. Here we test the hypothesis that MP1-dependent ERK signaling regulates motility of DU145 prostate cancer cells. We find that MP1 is required for motility on fibronectin, but not for motility stimulated by serum or EGF. Surprisingly, MP1 appears not to function through its known binding partners MEK1 or PAK1, suggesting the existence of a novel pathway by which MP1 can regulate motility on fibronectin. MP1 may function by regulating the stability or expression of paxillin, a key regulator of motility.
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Affiliation(s)
- Electa R Park
- Department of Pharmacology, LSU Health Sciences Center-New Orleans, LA, USA.
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Hsu RM, Tsai MH, Hsieh YJ, Lyu PC, Yu JS. Identification of MYO18A as a novel interacting partner of the PAK2/betaPIX/GIT1 complex and its potential function in modulating epithelial cell migration. Mol Biol Cell 2009; 21:287-301. [PMID: 19923322 PMCID: PMC2808764 DOI: 10.1091/mbc.e09-03-0232] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
MYO18A is found as a novel PAK2 binding partner via βPIX/GIT1. MYO18A-depleted cells showed dramatic changes in shape, actin stress fiber and membrane ruffle formation, and displayed increases in the number and size of focal adhesions and a decrease in cell migration, suggesting an important role of MYO18A in regulating epithelial cell migration. The p21-activated kinase (PAK) 2 is known to be involved in numerous biological functions, including the regulation of actin reorganization and cell motility. To better understand the mechanisms underlying this regulation, we herein used a proteomic approach to identify PAK2-interacting proteins in human epidermoid carcinoma A431 cells. We found that MYO18A, an emerging member of the myosin superfamily, is a novel PAK2 binding partner. Using a siRNA knockdown strategy and in vitro binding assay, we discovered that MYO18A binds to PAK2 through the βPIX/GIT1 complex. Under normal conditions, MYO18A and PAK2 colocalized in lamellipodia and membrane ruffles. Interestingly, knockdown of MYO18A in cells did not prevent formation of the PAK2/βPIX/GIT1 complex, but rather apparently changed its localization to focal adhesions. Moreover, MYO18A-depleted cells showed dramatic changes in morphology and actin stress fiber and membrane ruffle formation and displayed increases in the number and size of focal adhesions. Migration assays revealed that MYO18A-depleted cells had decreased cell motility, and reexpression of MYO18A restored their migration ability. Collectively, our findings indicate that MYO18A is a novel binding partner of the PAK2/βPIX/GIT1 complex and suggest that MYO18A may play an important role in regulating epithelial cell migration via affecting multiple cell machineries.
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Affiliation(s)
- Rae-Mann Hsu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China
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Kahsai AW, Zhu S, Fenteany G. G protein-coupled receptor kinase 2 activates radixin, regulating membrane protrusion and motility in epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1803:300-10. [PMID: 19913059 DOI: 10.1016/j.bbamcr.2009.11.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 11/03/2009] [Accepted: 11/04/2009] [Indexed: 12/11/2022]
Abstract
Ezrin/radixin/moesin (ERM) proteins are membrane-cytoskeleton linkers that also have roles in signal transduction. Here we show that G protein-coupled receptor kinase 2 (GRK2) regulates membrane protrusion and cell migration during wound closure in Madin-Darby canine kidney (MDCK) epithelial cell monolayers at least partly through activating phosphorylation of radixin on a conserved, regulatory C-terminal Thr residue. GRK2 phosphorylated radixin exclusively on Thr 564 in vitro. Expression of a phosphomimetic (Thr-564-to-Asp) mutant of radixin resulted in increased Rac1 activity, membrane protrusion and cell motility in MDCK cells, suggesting that radixin functions "upstream" of Rac1, presumably as a scaffolding protein. Phosphorylation of ERM proteins was highest during the most active phase of epithelial cell sheet migration over the course of wound closure. In view of these results, we explored the mode of action of quinocarmycin/quinocarcin analog DX-52-1, an inhibitor of cell migration and radixin function with considerable selectivity for radixin over the other ERM proteins, finding that its mechanism of inhibition of radixin does not appear to involve binding and antagonism at the site of regulatory phosphorylation.
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Affiliation(s)
- Alem W Kahsai
- Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA
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Aurora-A phosphorylates, activates, and relocalizes the small GTPase RalA. Mol Cell Biol 2009; 30:508-23. [PMID: 19901077 DOI: 10.1128/mcb.00916-08] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The small GTPase Ras, which transmits extracellular signals to the cell, and the kinase Aurora-A, which promotes proper mitosis, can both be inappropriately activated in human tumors. Here, we show that Aurora-A in conjunction with oncogenic Ras enhances transformed cell growth. Furthermore, such transformation and in some cases also tumorigenesis depend upon S194 of RalA, a known Aurora-A phosphorylation site. Aurora-A promotes not only RalA activation but also translocation from the plasma membrane and activation of the effector protein RalBP1. Taken together, these data suggest that Aurora-A may converge upon oncogenic Ras signaling through RalA.
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Rollason R, Korolchuk V, Hamilton C, Jepson M, Banting G. A CD317/tetherin-RICH2 complex plays a critical role in the organization of the subapical actin cytoskeleton in polarized epithelial cells. ACTA ACUST UNITED AC 2009; 184:721-36. [PMID: 19273615 PMCID: PMC2686410 DOI: 10.1083/jcb.200804154] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
CD317/tetherin is a lipid raft–associated integral membrane protein with a novel topology. It has a short N-terminal cytosolic domain, a conventional transmembrane domain, and a C-terminal glycosyl-phosphatidylinositol anchor. We now show that CD317 is expressed at the apical surface of polarized epithelial cells, where it interacts indirectly with the underlying actin cytoskeleton. CD317 is linked to the apical actin network via the proteins RICH2, EBP50, and ezrin. Knocking down expression of either CD317 or RICH2 gives rise to the same phenotype: a loss of the apical actin network with concomitant loss of apical microvilli, an increase in actin bundles at the basal surface, and a reduction in cell height without any loss of tight junctions, transepithelial resistance, or the polarized targeting of apical and basolateral membrane proteins. Thus, CD317 provides a physical link between lipid rafts and the apical actin network in polarized epithelial cells and is crucial for the maintenance of microvilli in such cells.
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Affiliation(s)
- Ruth Rollason
- Department of Biochemistry, University of Bristol, Bristol BS8 1TD, England, UK
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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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Luo S, Rubinsztein DC. Huntingtin promotes cell survival by preventing Pak2 cleavage. J Cell Sci 2009; 122:875-85. [PMID: 19240112 DOI: 10.1242/jcs.050013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Huntington's disease is caused by a polyglutamine expansion in the huntingtin protein. Wild-type huntingtin, by contrast, appears to protect cells from pro-apoptotic insults. Here we describe a novel anti-apoptotic function for huntingtin. When cells are exposed to Fas-related signals, the ubiquitously expressed p21-activated kinase 2 (Pak2) can be activated via cleavage by caspases to release a constitutively active C-terminal fragment, which mediates cell death. Our data show that huntingtin interacts with Pak2. Overexpression of huntingtin significantly inhibits caspase-3-mediated and caspase-8-mediated cleavage of Pak2 in cells. Moreover, huntingtin prevents Pak2 cleavage by caspase-3 and caspase-8 in vitro. Although huntingtin is cytoprotective in wild-type cells that are exposed to TNFalpha, it has no significant benefit in TNFalpha-treated cells with Pak2 knockdown. Thus, huntingtin exerts anti-apoptotic effects by binding to Pak2, which reduces the abilities of caspase-3 and caspase-8 to cleave Pak2 and convert it into a mediator of cell death.
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Affiliation(s)
- Shouqing Luo
- Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
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Lettau M, Pieper J, Janssen O. Nck adapter proteins: functional versatility in T cells. Cell Commun Signal 2009; 7:1. [PMID: 19187548 PMCID: PMC2661883 DOI: 10.1186/1478-811x-7-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Accepted: 02/02/2009] [Indexed: 01/16/2023] Open
Abstract
Nck is a ubiquitously expressed adapter protein that is almost exclusively built of one SH2 domain and three SH3 domains. The two isoproteins of Nck are functionally redundant in many aspects and differ in only few amino acids that are mostly located in the linker regions between the interaction modules. Nck proteins connect receptor and non-receptor tyrosine kinases to the machinery of actin reorganisation. Thereby, Nck regulates activation-dependent processes during cell polarisation and migration and plays a crucial role in the signal transduction of a variety of receptors including for instance PDGF-, HGF-, VEGF- and Ephrin receptors. In most cases, the SH2 domain mediates binding to the phosphorylated receptor or associated phosphoproteins, while SH3 domain interactions lead to the formation of larger protein complexes. In T lymphocytes, Nck plays a pivotal role in the T cell receptor (TCR)-induced reorganisation of the actin cytoskeleton and the formation of the immunological synapse. However, in this context, two different mechanisms and adapter complexes are discussed. In the first scenario, dependent on an activation-induced conformational change in the CD3epsilon subunits, a direct binding of Nck to components of the TCR/CD3 complex was shown. In the second scenario, Nck is recruited to the TCR complex via phosphorylated Slp76, another central constituent of the membrane proximal activation complex. Over the past years, a large number of putative Nck interactors have been identified in different cellular systems that point to diverse additional functions of the adapter protein, e.g. in the control of gene expression and proliferation.
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Affiliation(s)
- Marcus Lettau
- University Hospital Schleswig-Holstein Campus Kiel, Institute of Immunology, Molecular Immunology, Arnold-Heller-Str 3, Bldg 17, D-24105 Kiel, Germany.
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