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Han KA, Ko J. Orchestration of synaptic functions by WAVE regulatory complex-mediated actin reorganization. Exp Mol Med 2023; 55:1065-1075. [PMID: 37258575 PMCID: PMC10318009 DOI: 10.1038/s12276-023-01004-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/13/2023] [Accepted: 03/13/2023] [Indexed: 06/02/2023] Open
Abstract
The WAVE regulatory complex (WRC), composed of five components-Cyfip1/Sra1, WAVE/Scar, Abi, Nap1/Nckap1, and Brk1/HSPC300-is essential for proper actin cytoskeletal dynamics and remodeling in eukaryotic cells, likely by matching various patterned signals to Arp2/3-mediated actin nucleation. Accumulating evidence from recent studies has revealed diverse functions of the WRC in neurons, demonstrating its crucial role in dictating the assembly of molecular complexes for the patterning of various trans-synaptic signals. In this review, we discuss recent exciting findings on the physiological role of the WRC in regulating synaptic properties and highlight the involvement of WRC dysfunction in various brain disorders.
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Affiliation(s)
- Kyung Ah Han
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, Korea
- Center for Synapse Diversity and Specificity, DGIST, Daegu, 42988, Korea
| | - Jaewon Ko
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu, 42988, Korea.
- Center for Synapse Diversity and Specificity, DGIST, Daegu, 42988, Korea.
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Hogestyn JM, Salois G, Xie L, Apa C, Youngyunpipatkul J, Pröschel C, Mayer-Pröschel M. Expression of the human herpesvirus 6A latency-associated transcript U94A impairs cytoskeletal functions in human neural cells. Mol Cell Neurosci 2022; 123:103770. [PMID: 36055520 PMCID: PMC10124163 DOI: 10.1016/j.mcn.2022.103770] [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: 05/04/2022] [Revised: 08/12/2022] [Accepted: 08/20/2022] [Indexed: 12/30/2022] Open
Abstract
Many neurodegenerative diseases have a multifactorial etiology and variable course of progression that cannot be explained by current models. Neurotropic viruses have long been suggested to play a role in these diseases, although their exact contributions remain unclear. Human herpesvirus 6A (HHV-6A) is one of the most common viruses detected in the adult brain, and has been clinically associated with multiple sclerosis (MS), and, more recently, Alzheimer's disease (AD). HHV-6A is a ubiquitous viral pathogen capable of infecting glia and neurons. Primary infection in childhood is followed by the induction of latency, characterized by expression of the U94A viral transcript in the absence of viral replication. Here we examine the effects of U94A on cells of the central nervous system. We found that U94A expression inhibits the migration and impairs cytoplasmic maturation of human oligodendrocyte precursor cells (OPCs) without affecting their viability, a phenotype that may contribute to the failure of remyelination seen in many patients with MS. A subsequent proteomics analysis of U94A expression OPCs revealed altered expression of genes involved in tubulin associated cytoskeletal regulation. As HHV-6A seems to significantly be associated with early AD pathology, we extended our initially analysis of the impact of U94A on human derived neurons. We found that U94A expression inhibits neurite outgrowth of primary human cortical neurons and impairs synapse maturation. Based on these data we suggest that U94A expression by latent HHV-6A in glial cells and neurons renders them susceptible to dysfunction and degeneration. Therefore, latent viral infections of the brain represent a unique pathological risk factor that may contribute to disease processes.
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Affiliation(s)
- Jessica M Hogestyn
- Department of Biomedical Genetics, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA; Department of Neuroscience, School of Medicine and Dentistry, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA
| | - Garrick Salois
- Department of Biomedical Genetics, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA; Department of Neuroscience, School of Medicine and Dentistry, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA
| | - Li Xie
- Department of Biomedical Genetics, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA
| | - Connor Apa
- Department of Biomedical Genetics, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA; Stem cell and Regenerative Medicine Institute, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA
| | - Justin Youngyunpipatkul
- Department of Biomedical Genetics, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA
| | - Christoph Pröschel
- Department of Biomedical Genetics, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA; Stem cell and Regenerative Medicine Institute, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA
| | - Margot Mayer-Pröschel
- Department of Biomedical Genetics, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA; Department of Neuroscience, School of Medicine and Dentistry, 601 Elmwood Avenue, Box 633, University of Rochester, Rochester, NY 14642, USA,.
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Circular dorsal ruffles disturb the growth factor-induced PI3K-AKT pathway in hepatocellular carcinoma Hep3B cells. Cell Commun Signal 2022; 20:102. [PMID: 35799301 PMCID: PMC9264614 DOI: 10.1186/s12964-022-00911-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 06/05/2022] [Indexed: 11/10/2022] Open
Abstract
Background Circular dorsal ruffles (CDRs) are rounded membrane ruffles induced on the dorsal surfaces of cells stimulated by growth factors (GF). They can serve as signal platforms to activate AKT protein kinase. After GF stimulation, phosphatidylinositol 3-kinase (PI3K) generates phosphatidylinositol (3,4,5)-triphosphate (PIP3) in the plasma membrane. PIP3 accumulates inside CDRs, recruits AKT into the structures, and phosphorylates them (pAKT). Given the importance of the PI3K-AKT pathway in GF signaling, CDRs are likely involved in cell growth. Interestingly, some cancer cell lines express CDRs. We hypothesized that CDRs contribute to carcinogenesis by modulating the AKT pathway. In the present study, we identified CDR-expressing cancer cell lines and investigated their cellular functions. Methods CDR formation was examined in six cancer cell lines in response to epidermal growth factor (EGF) and insulin. The morphology of the CDRs was characterized, and the related signaling molecules were observed using confocal and scanning electron microscopy. The role of CDRs in the AKT pathway was studied using biochemical analysis. The actin inhibitor cytochalasin D (Cyto D) and the PI3K inhibitor TGX221 were used to block CDRs. Results GF treatment induced CDRs in the hepatocellular carcinoma (HCC) Hep3B cell line, but not in others, including HCC cell lines HepG2 and Huh7, and the LO2 hepatocyte cell line. Confocal microscopy and western blot analysis showed that the PI3K-PIP3-AKT pathway was activated at the CDRs and that receptor proteins were recruited to the structures. Cyto D and TGX221 completely blocked CDRs and partially attenuated GF-induced pAKT. These results indicate that CDRs regulate the receptor-mediated PI3K-AKT pathway in Hep3B cells and the existence of CDR-independent pAKT mechanisms. Conclusions Our results showed that CDRs modulate the AKT pathway in Hep3B cells. Since CDRs were not observed in other HCC and hepatocyte cell lines, we propose that CDRs in Hep3B would determine the carcinoma characteristic of the cell by aberrantly triggering the AKT pathway. Signaling molecules involved in CDR formation are promising therapeutic targets for some types of HCC. Video abstract
Supplementary Information The online version contains supplementary material available at 10.1186/s12964-022-00911-6.
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Kramer DA, Piper HK, Chen B. WASP family proteins: Molecular mechanisms and implications in human disease. Eur J Cell Biol 2022; 101:151244. [PMID: 35667337 PMCID: PMC9357188 DOI: 10.1016/j.ejcb.2022.151244] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 05/25/2022] [Accepted: 05/27/2022] [Indexed: 02/08/2023] Open
Abstract
Proteins of the Wiskott-Aldrich syndrome protein (WASP) family play a central role in regulating actin cytoskeletal dynamics in a wide range of cellular processes. Genetic mutations or misregulation of these proteins are tightly associated with many diseases. The WASP-family proteins act by transmitting various upstream signals to their conserved WH2-Central-Acidic (WCA) peptide sequence at the C-terminus, which in turn binds to the Arp2/3 complex to stimulate the formation of branched actin networks at membranes. Despite this common feature, the regulatory mechanisms and cellular functions of distinct WASP-family proteins are very different. Here, we summarize and clarify our current understanding of WASP-family proteins and how disruption of their functions is related to human disease.
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Affiliation(s)
- Daniel A Kramer
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA
| | - Hannah K Piper
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA
| | - Baoyu Chen
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, 2437 Pammel Drive, Ames, IA 50011, USA.
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The Role of WAVE2 Signaling in Cancer. Biomedicines 2021; 9:biomedicines9091217. [PMID: 34572403 PMCID: PMC8464821 DOI: 10.3390/biomedicines9091217] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 11/18/2022] Open
Abstract
The Wiskott–Aldrich syndrome protein (WASP) and WASP family verprolin-homologous protein (WAVE)—WAVE1, WAVE2 and WAVE3 regulate rapid reorganization of cortical actin filaments and have been shown to form a key link between small GTPases and the actin cytoskeleton. Upon receiving upstream signals from Rho-family GTPases, the WASP and WAVE family proteins play a significant role in polymerization of actin cytoskeleton through activation of actin-related protein 2/3 complex (Arp2/3). The Arp2/3 complex, once activated, forms actin-based membrane protrusions essential for cell migration and cancer cell invasion. Thus, by activation of Arp2/3 complex, the WAVE and WASP family proteins, as part of the WAVE regulatory complex (WRC), have been shown to play a critical role in cancer cell invasion and metastasis, drawing significant research interest over recent years. Several studies have highlighted the potential for targeting the genes encoding either part of or a complete protein from the WASP/WAVE family as therapeutic strategies for preventing the invasion and metastasis of cancer cells. WAVE2 is well documented to be associated with the pathogenesis of several human cancers, including lung, liver, pancreatic, prostate, colorectal and breast cancer, as well as other hematologic malignancies. This review focuses mainly on the role of WAVE2 in the development, invasion and metastasis of different types of cancer. This review also summarizes the molecular mechanisms that regulate the activity of WAVE2, as well as those oncogenic pathways that are regulated by WAVE2 to promote the cancer phenotype. Finally, we discuss potential therapeutic strategies that target WAVE2 or the WAVE regulatory complex, aimed at preventing or inhibiting cancer invasion and metastasis.
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Sreelekshmi M, Raghu KG. Vanillic acid mitigates the impairments in glucose metabolism in HepG2 cells through BAD-GK interaction during hyperinsulinemia. J Biochem Mol Toxicol 2021; 35:1-8. [PMID: 33651899 DOI: 10.1002/jbt.22750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 12/02/2020] [Accepted: 02/18/2021] [Indexed: 11/09/2022]
Abstract
Glucokinase (GK), a key regulator of hepatic glucose metabolism in the liver and glucose sensor and mediator in the secretion of insulin in the pancreas, is not studied in detail for its therapeutic application in diabetes. Herein, we study the alteration in GK activity during hyperinsulinemia-induced insulin resistance in HepG2 cells. We also investigated the link between GK and Bcl-2-associated death receptor (BAD) during hyperinsulinemia. There are emerging demands for GK activators from natural resources, and we selected vanillic acid (VA) to evaluate its potential as GK activators during hyperinsulinemia in HepG2 cells. VA is a phenolic compound and a commonly used food additive in many food industries. We found that VA safeguarded GK inhibition during hyperinsulinemia significantly in HepG2 cells. VA also prevented the depletion of glycogen synthesis during hyperinsulinemia, which is evident from protein expression studies of phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, glycogen synthase, and glycogen synthase kinase-3β. This was associated with activation of BAD activity, which was also confirmed by Western blotting. Molecular docking revealed strong binding between GK active site and VA, supporting their strong interaction. These are the first in vitro data to indicate the beneficial properties of VA with respect to insulin resistance induced by hyperinsulinemia by GK activation. Since it is activated via BAD, the hypoglycemia associated with general GK activation is not expected here and therefore has significant implications for future therapies against diabetes.
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Affiliation(s)
- Mohan Sreelekshmi
- Biochemistry and Molecular Mechanism Laboratory, Agro-processing and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, Kerala, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Kozhiparambil Gopalan Raghu
- Biochemistry and Molecular Mechanism Laboratory, Agro-processing and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, Kerala, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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Di Benedetto G, Lefkimmiatis K, Pozzan T. The basics of mitochondrial cAMP signalling: Where, when, why. Cell Calcium 2020; 93:102320. [PMID: 33296837 DOI: 10.1016/j.ceca.2020.102320] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/16/2020] [Accepted: 11/16/2020] [Indexed: 12/15/2022]
Abstract
Cytosolic cAMP signalling in live cells has been extensively investigated in the past, while only in the last decade the existence of an intramitochondrial autonomous cAMP homeostatic system began to emerge. Thanks to the development of novel tools to investigate cAMP dynamics and cAMP/PKA-dependent phosphorylation within the matrix and in other mitochondrial compartments, it is now possible to address directly and in intact living cells a series of questions that until now could be addressed only by indirect approaches, in isolated organelles or through subcellular fractionation studies. In this contribution we discuss the mechanisms that regulate cAMP dynamics at the surface and inside mitochondria, and its crosstalk with organelle Ca2+ handling. We then address a series of still unsolved questions, such as the intramitochondrial localization of key elements of the cAMP signaling toolkit, e.g., adenylate cyclases, phosphodiesterases, protein kinase A (PKA) and Epac. Finally, we discuss the evidence for and against the existence of an intramitochondrial PKA pool and the functional role of cAMP increases within the organelle matrix.
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Affiliation(s)
- Giulietta Di Benedetto
- Neuroscience Institute, National Research Council of Italy (CNR), 35121 Padova, Italy; Veneto Institute of Molecular Medicine, Foundation for Advanced Biomedical Research, 35129 Padova, Italy.
| | - Konstantinos Lefkimmiatis
- Veneto Institute of Molecular Medicine, Foundation for Advanced Biomedical Research, 35129 Padova, Italy; Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy
| | - Tullio Pozzan
- Neuroscience Institute, National Research Council of Italy (CNR), 35121 Padova, Italy; Veneto Institute of Molecular Medicine, Foundation for Advanced Biomedical Research, 35129 Padova, Italy; Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy
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Qasim H, McConnell BK. AKAP12 Signaling Complex: Impacts of Compartmentalizing cAMP-Dependent Signaling Pathways in the Heart and Various Signaling Systems. J Am Heart Assoc 2020; 9:e016615. [PMID: 32573313 PMCID: PMC7670535 DOI: 10.1161/jaha.120.016615] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Heart failure is a complex clinical syndrome, represented as an impairment in ventricular filling and myocardial blood ejection. As such, heart failure is one of the leading causes of death in the United States. With a mortality rate of 1 per 8 individuals and a prevalence of 6.2 million Americans, it has been projected that heart failure prevalence will increase by 46% by 2030. Cardiac remodeling (a general determinant of heart failure) is regulated by an extensive network of intertwined intracellular signaling pathways. The ability of signalosomes (molecular signaling complexes) to compartmentalize several cellular pathways has been recently established. These signalosome signaling complexes provide an additional level of specificity to general signaling pathways by regulating the association of upstream signals with downstream effector molecules. In cardiac myocytes, the AKAP12 (A‐kinase anchoring protein 12) scaffolds a large signalosome that orchestrates spatiotemporal signaling through stabilizing pools of phosphatases and kinases. Predominantly upon β‐AR (β2‐adrenergic‐receptor) stimulation, the AKAP12 signalosome is recruited near the plasma membrane and binds tightly to β‐AR. Thus, one major function of AKAP12 is compartmentalizing PKA (protein kinase A) signaling near the plasma membrane. In addition, it is involved in regulating desensitization, downregulation, and recycling of β‐AR. In this review, the critical roles of AKAP12 as a scaffold protein in mediating signaling downstream GPCRs (G protein–coupled receptor) are discussed with an emphasis on its reported and potential roles in cardiovascular disease initiation and progression.
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Affiliation(s)
- Hanan Qasim
- Department of Pharmacological and Pharmaceutical Sciences College of Pharmacy University of Houston TX
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences College of Pharmacy University of Houston TX
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Cuentas-Condori A, Mulcahy B, He S, Palumbos S, Zhen M, Miller DM. C. elegans neurons have functional dendritic spines. eLife 2019; 8:e47918. [PMID: 31584430 PMCID: PMC6802951 DOI: 10.7554/elife.47918] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 10/03/2019] [Indexed: 12/15/2022] Open
Abstract
Dendritic spines are specialized postsynaptic structures that transduce presynaptic signals, are regulated by neural activity and correlated with learning and memory. Most studies of spine function have focused on the mammalian nervous system. However, spine-like protrusions have been reported in C. elegans (Philbrook et al., 2018), suggesting that the experimental advantages of smaller model organisms could be exploited to study the biology of dendritic spines. Here, we used super-resolution microscopy, electron microscopy, live-cell imaging and genetics to show that C. elegans motor neurons have functional dendritic spines that: (1) are structurally defined by a dynamic actin cytoskeleton; (2) appose presynaptic dense projections; (3) localize ER and ribosomes; (4) display calcium transients triggered by presynaptic activity and propagated by internal Ca++ stores; (5) respond to activity-dependent signals that regulate spine density. These studies provide a solid foundation for a new experimental paradigm that exploits the power of C. elegans genetics and live-cell imaging for fundamental studies of dendritic spine morphogenesis and function.
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Affiliation(s)
| | - Ben Mulcahy
- Lunenfeld-Tanenbaum Research InstituteUniversity of TorontoTorontoCanada
| | - Siwei He
- Neuroscience ProgramVanderbilt UniversityNashvilleUnited States
| | - Sierra Palumbos
- Neuroscience ProgramVanderbilt UniversityNashvilleUnited States
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research InstituteUniversity of TorontoTorontoCanada
| | - David M Miller
- Department of Cell and Developmental BiologyVanderbilt UniversityNashvilleUnited States
- Neuroscience ProgramVanderbilt UniversityNashvilleUnited States
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Bledzka K, Schiemann B, Schiemann WP, Fox P, Plow EF, Sossey-Alaoui K. The WAVE3-YB1 interaction regulates cancer stem cells activity in breast cancer. Oncotarget 2017; 8:104072-104089. [PMID: 29262622 PMCID: PMC5732788 DOI: 10.18632/oncotarget.22009] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 09/29/2017] [Indexed: 12/12/2022] Open
Abstract
Resistance to therapy is the main cause of tumor recurrence and metastasis and cancer stem cells (CSCs) play a crucial role in this process, especially in triple-negative breast cancers (TNBCs). Unfortunately, no FDA-approved treatment is currently available for this subtype of BC, which explains the high rate of mortality in patients with TNBC tumors. WAVE3, a member of the WASP/WAVE actin-cytoskeleton remodeling family of protein, has been established as a major driver of tumor progression and metastasis of several solid tumors, including those originating in the breast. Our recently published studies found WAVE3 to mediate the process of chemoresistance in TNBCs. The molecular mechanisms whereby WAVE3 regulates chemoresistance in TNBC tumors remains largely unknown, as does the role of WAVE3 in CSC maintenance. Here we show that WAVE3 promotes CSC self-renewal and regulates transcription of CSC-specific genes, which, in part, provides a mechanistic explanation for the function of WAVE3 in chemoresistance in TNBCs. Our data show that WAVE3 is enriched in the CSC-subpopulation of TNBC cell lines. Knockout of WAVE3 via CRISPR/Cas9 significantly attenuates the CSC-subpopulation and inhibits transcription of CSC transcription factors. Mechanistically, we established a link between WAVE3 and the Y-box-binding protein-1 (YB1), a transcription factor and CSC-maintenance gene. Indeed, the interaction of WAVE3 with YB1 is required for YB1 translocation to the nucleus of cancer cells, and activation of transcription of CSC-specific genes. Our findings identify a new WAVE3/YB1 signaling axis that regulates the CSC-mediated resistance to therapy and opens a new therapeutic window for TNBCs treatment.
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Affiliation(s)
- Kamila Bledzka
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | | | | | - Paul Fox
- Department of Cellular and Molecular Medicine, Cleveland, Ohio, USA
| | - Edward F Plow
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Khalid Sossey-Alaoui
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
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The Arp2/3 Complex Is Essential for Distinct Stages of Spine Synapse Maturation, Including Synapse Unsilencing. J Neurosci 2017; 36:9696-709. [PMID: 27629719 DOI: 10.1523/jneurosci.0876-16.2016] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/02/2016] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED Dendritic filopodia are actin-rich structures that are thought to contribute to early spine synapse formation; however, the actin regulatory proteins important for early synaptogenesis are poorly defined. Using organotypic hippocampal slice cultures and primary neuron hippocampal cultures from Arp2/3 conditional knock-out mice, we analyze the roles of the Arp2/3 complex, an actin regulator that creates branched actin networks, and demonstrate it is essential for distinct stages of both structural and functional maturation of excitatory spine synapses. Our data show that initially the Arp2/3 complex inhibits the formation of dendritic filopodia but that later during development, the Arp2/3 complex drives the morphological maturation from filopodia to typical spine morphology. Furthermore, we demonstrate that although the Arp2/3 complex is not required for key spine maturation steps, such as presynaptic contact and recruitment of MAGUK (membrane-associated guanylate kinase) scaffolding proteins or NMDA receptors, it is necessary for the recruitment of AMPA receptors. This latter process, also known as synapse unsilencing, is a final and essential step in the neurodevelopment of excitatory postsynaptic synaptogenesis, setting the stage for neuronal interconnectivity. These findings provide the first evidence that the Arp2/3 complex is directly involved in functional maturation of dendritic spines during the developmental period of spinogenesis. SIGNIFICANCE STATEMENT Excitatory spine synapse formation (spinogenesis) is a poorly understood yet pivotal period of neurodevelopment that occurs within 2-3 weeks after birth. Neurodevelopmental disorders such as intellectual disability and autism are characterized by abnormal spine structure, which may arise from abnormal excitatory synaptogenesis. The initial stage of spinogenesis is thought to begin with the emergence of actin-rich dendritic filopodia that initiate contact with presynaptic axonal boutons. However, it remains enigmatic how actin cytoskeletal regulation directs dendritic filopodial emergence or their subsequent maturation into dendritic spines during development and on into adulthood. In this study, we provide the first evidence that the Arp2/3 complex, a key actin nucleator, is involved in distinct stages of spine formation and is required for synapse unsilencing.
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12
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Pseudoscaffolds and anchoring proteins: the difference is in the details. Biochem Soc Trans 2017; 45:371-379. [PMID: 28408477 DOI: 10.1042/bst20160329] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/18/2017] [Accepted: 01/20/2017] [Indexed: 12/18/2022]
Abstract
Pseudokinases and pseudophosphatases possess the ability to bind substrates without catalyzing their modification, thereby providing a mechanism to recruit potential phosphotargets away from active enzymes. Since many of these pseudoenzymes possess other characteristics such as localization signals, separate catalytic sites, and protein-protein interaction domains, they have the capacity to influence signaling dynamics in local environments. In a similar manner, the targeting of signaling enzymes to subcellular locations by A-kinase-anchoring proteins (AKAPs) allows for precise and local control of second messenger signaling events. Here, we will discuss how pseudoenzymes form 'pseudoscaffolds' and compare and contrast this compartment-specific regulatory role with the signal organization properties of AKAPs. The mitochondria will be the focus of this review, as they are dynamic organelles that influence a broad range of cellular processes such as metabolism, ATP synthesis, and apoptosis.
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Uezu A, Kanak DJ, Bradshaw TWA, Soderblom EJ, Catavero CM, Burette AC, Weinberg RJ, Soderling SH. Identification of an elaborate complex mediating postsynaptic inhibition. Science 2017; 353:1123-9. [PMID: 27609886 DOI: 10.1126/science.aag0821] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/25/2016] [Indexed: 12/13/2022]
Abstract
Inhibitory synapses dampen neuronal activity through postsynaptic hyperpolarization. The composition of the inhibitory postsynapse and the mechanistic basis of its regulation, however, remain poorly understood. We used an in vivo chemico-genetic proximity-labeling approach to discover inhibitory postsynaptic proteins. Quantitative mass spectrometry not only recapitulated known inhibitory postsynaptic proteins but also revealed a large network of new proteins, many of which are either implicated in neurodevelopmental disorders or are of unknown function. Clustered regularly interspaced short palindromic repeats (CRISPR) depletion of one of these previously uncharacterized proteins, InSyn1, led to decreased postsynaptic inhibitory sites, reduced the frequency of miniature inhibitory currents, and increased excitability in the hippocampus. Our findings uncover a rich and functionally diverse assemblage of previously unknown proteins that regulate postsynaptic inhibition and might contribute to developmental brain disorders.
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Affiliation(s)
- Akiyoshi Uezu
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Daniel J Kanak
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Tyler W A Bradshaw
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Erik J Soderblom
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA. Duke Proteomics and Metabolomics Shared Resource and Duke Center for Genomic and Computational Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Christina M Catavero
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Alain C Burette
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA. Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Richard J Weinberg
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA. Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Scott H Soderling
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA. The Department of Neurobiology, Duke University Medical School, Durham, NC 27703, USA.
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Oliveros A, Starski P, Lindberg D, Choi S, Heppelmann CJ, Dasari S, Choi DS. Label-Free Neuroproteomics of the Hippocampal-Accumbal Circuit Reveals Deficits in Neurotransmitter and Neuropeptide Signaling in Mice Lacking Ethanol-Sensitive Adenosine Transporter. J Proteome Res 2017; 16:1445-1459. [PMID: 27998058 DOI: 10.1021/acs.jproteome.6b00830] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The neural circuit of the dorsal hippocampus (dHip) and nucleus accumbens (NAc) contributes to cue-induced learning and addictive behaviors, as demonstrated by the escalation of ethanol-seeking behaviors observed following deletion of the adenosine equilibrative nucleoside transporter 1 (ENT1-/-) in mice. Here we perform quantitative LC-MS/MS neuroproteomics in the dHip and NAc of ENT1-/- mice. Using Ingenuity Pathway Analysis, we identified proteins associated with increased long-term potentiation, ARP2/3-mediated actin cytoskeleton signaling and protein expression patterns suggesting deficits in glutamate degradation, GABAergic signaling, as well as significant changes in bioenergetics and energy homeostasis (oxidative phosphorylation, TCA cycle, and glycolysis). These pathways are consistent with previously reported behavioral and biochemical phenotypes that typify mice lacking ENT1. Moreover, we validated decreased expression of the SNARE complex protein VAMP1 (synaptobrevin-1) in the dHip as well as decreased expression of pro-dynorphin (PDYN), neuroendocrine convertase (PCSK1), and Leu-Enkephalin (dynorphin-A) in the NAc. Taken together, our proteomic approach provides novel pathways indicating that ENT1-regulated signaling is essential for neurotransmitter release and neuropeptide processing, both of which underlie learning and reward-seeking behaviors.
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Affiliation(s)
- Alfredo Oliveros
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Phillip Starski
- Neurobiology of Disease Program, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Daniel Lindberg
- Neurobiology of Disease Program, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Sun Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Carrie J Heppelmann
- Proteomics Research Center, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Surendra Dasari
- Division of Biomedical Statistics and Informatics, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Rochester, Minnesota 55905, United States.,Neurobiology of Disease Program, Mayo Clinic , Rochester, Minnesota 55905, United States.,Department of Psychiatry and Psychology, Mayo Clinic , Rochester, Minnesota 55905, United States
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15
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Huang GH, Sun ZL, Li HJ, Feng DF. Rho GTPase-activating proteins: Regulators of Rho GTPase activity in neuronal development and CNS diseases. Mol Cell Neurosci 2017; 80:18-31. [PMID: 28163190 DOI: 10.1016/j.mcn.2017.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 01/06/2017] [Accepted: 01/29/2017] [Indexed: 12/22/2022] Open
Abstract
The Rho family of small GTPases was considered as molecular switches in regulating multiple cellular events, including cytoskeleton reorganization. The Rho GTPase-activating proteins (RhoGAPs) are one of the major families of Rho GTPase regulators. RhoGAPs were initially considered negative mediators of Rho signaling pathways via their GAP domain. Recent studies have demonstrated that RhoGAPs also regulate numerous aspects of neuronal development and are related to various neurodegenerative diseases in GAP-dependent and GAP-independent manners. Moreover, RhoGAPs are regulated through various mechanisms, such as phosphorylation. To date, approximately 70 RhoGAPs have been identified; however, only a small portion has been thoroughly investigated. Thus, the characterization of important RhoGAPs in the central nervous system is crucial to understand their spatiotemporal role during different stages of neuronal development. In this review, we summarize the current knowledge of RhoGAPs in the brain with an emphasis on their molecular function, regulation mechanism and disease implications in the central nervous system.
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Affiliation(s)
- Guo-Hui Huang
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Zhao-Liang Sun
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Hong-Jiang Li
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Dong-Fu Feng
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China; Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China.
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16
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Hung WC, Yang JR, Yankaskas CL, Wong BS, Wu PH, Pardo-Pastor C, Serra SA, Chiang MJ, Gu Z, Wirtz D, Valverde MA, Yang JT, Zhang J, Konstantopoulos K. Confinement Sensing and Signal Optimization via Piezo1/PKA and Myosin II Pathways. Cell Rep 2016; 15:1430-1441. [PMID: 27160899 PMCID: PMC5341576 DOI: 10.1016/j.celrep.2016.04.035] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/07/2016] [Accepted: 04/04/2016] [Indexed: 12/01/2022] Open
Abstract
Cells adopt distinct signaling pathways to optimize cell locomotion in different physical microenvironments. However, the underlying mechanism that enables cells to sense and respond to physical confinement is unknown. Using microfabricated devices and substrate-printing methods along with FRET-based biosensors, we report that, as cells transition from unconfined to confined spaces, intracellular Ca2+ level is increased, leading to phosphodiesterase 1 (PDE1)-dependent suppression of PKA activity. This Ca2+ elevation requires Piezo1, a stretch-activated cation channel. Moreover, differential regulation of PKA and cell stiffness in unconfined versus confined cells is abrogated by dual, but not individual, inhibition of Piezo1 and myosin II, indicating that these proteins can independently mediate confinement sensing. Signals activated by Piezo1 and myosin II in response to confinement both feed into a signaling circuit that optimizes cell motility. This study provides a mechanism by which confinement-induced signaling enables cells to sense and adapt to different physical microenvironments.
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Affiliation(s)
- Wei-Chien Hung
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jessica R Yang
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Christopher L Yankaskas
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Bin Sheng Wong
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Pei-Hsun Wu
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Carlos Pardo-Pastor
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Carrera del Doctor Aiguader 88, Barcelona 08003, Spain
| | - Selma A Serra
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Carrera del Doctor Aiguader 88, Barcelona 08003, Spain
| | - Meng-Jung Chiang
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zhizhan Gu
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Denis Wirtz
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Miguel A Valverde
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Carrera del Doctor Aiguader 88, Barcelona 08003, Spain
| | - Joy T Yang
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Jin Zhang
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Konstantinos Konstantopoulos
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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17
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Li M, Quan C, Toth R, Campbell DG, MacKintosh C, Wang HY, Chen S. Fasting and Systemic Insulin Signaling Regulate Phosphorylation of Brain Proteins That Modulate Cell Morphology and Link to Neurological Disorders. J Biol Chem 2015; 290:30030-41. [PMID: 26499801 PMCID: PMC4705965 DOI: 10.1074/jbc.m115.668103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Indexed: 12/20/2022] Open
Abstract
Diabetes is strongly associated with cognitive decline, but the molecular reasons are unknown. We found that fasting and peripheral insulin promote phosphorylation and dephosphorylation, respectively, of specific residues on brain proteins including cytoskeletal regulators such as slit-robo GTPase-activating protein 3 (srGAP3) and microtubule affinity-regulating protein kinases (MARKs), in which deficiency or dysregulation is linked to neurological disorders. Fasting activates protein kinase A (PKA) but not PKB/Akt signaling in the brain, and PKA can phosphorylate the purified srGAP3. The phosphorylation of srGAP3 and MARKs were increased when PKA signaling was activated in primary neurons. Knockdown of PKA decreased the phosphorylation of srGAP3. Furthermore, WAVE1, a protein kinase A-anchoring protein, formed a complex with srGAP3 and PKA in the brain of fasted mice to facilitate the phosphorylation of srGAP3 by PKA. Although brain cells have insulin receptors, our findings are inconsistent with the down-regulation of phosphorylation of target proteins being mediated by insulin signaling within the brain. Rather, our findings infer that systemic insulin, through a yet unknown mechanism, inhibits PKA or protein kinase(s) with similar specificity and/or activates an unknown phosphatase in the brain. Ser858 of srGAP3 was identified as a key regulatory residue in which phosphorylation by PKA enhanced the GAP activity of srGAP3 toward its substrate, Rac1, in cells, thereby inhibiting the action of this GTPase in cytoskeletal regulation. Our findings reveal novel mechanisms linking peripheral insulin sensitivity with cytoskeletal remodeling in neurons, which may help to explain the association of diabetes with neurological disorders such as Alzheimer disease.
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Affiliation(s)
- Min Li
- From the State Key Laboratory of Pharmaceutical Biotechnology and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Pukou District, Nanjing 210061, China
| | - Chao Quan
- From the State Key Laboratory of Pharmaceutical Biotechnology and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Pukou District, Nanjing 210061, China
| | - Rachel Toth
- the Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom, and
| | - David G Campbell
- the Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom, and
| | - Carol MacKintosh
- the Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Hong Yu Wang
- From the State Key Laboratory of Pharmaceutical Biotechnology and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Pukou District, Nanjing 210061, China,
| | - Shuai Chen
- From the State Key Laboratory of Pharmaceutical Biotechnology and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Pukou District, Nanjing 210061, China,
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18
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Samelson BK, Gore BB, Whiting JL, Nygren PJ, Purkey AM, Colledge M, Langeberg LK, Dell'Acqua ML, Zweifel LS, Scott JD. A-kinase Anchoring Protein 79/150 Recruits Protein Kinase C to Phosphorylate Roundabout Receptors. J Biol Chem 2015; 290:14107-19. [PMID: 25882844 DOI: 10.1074/jbc.m115.637470] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Indexed: 01/08/2023] Open
Abstract
Anchoring proteins direct protein kinases and phosphoprotein phosphatases toward selected substrates to control the efficacy, context, and duration of neuronal phosphorylation events. The A-kinase anchoring protein AKAP79/150 interacts with protein kinase A (PKA), protein kinase C (PKC), and protein phosphatase 2B (calcineurin) to modulate second messenger signaling events. In a mass spectrometry-based screen for additional AKAP79/150 binding partners, we have identified the Roundabout axonal guidance receptor Robo2 and its ligands Slit2 and Slit3. Biochemical and cellular approaches confirm that a linear sequence located in the cytoplasmic tail of Robo2 (residues 991-1070) interfaces directly with sites on the anchoring protein. Parallel studies show that AKAP79/150 interacts with the Robo3 receptor in a similar manner. Immunofluorescent staining detects overlapping expression patterns for murine AKAP150, Robo2, and Robo3 in a variety of brain regions, including hippocampal region CA1 and the islands of Calleja. In vitro kinase assays, peptide spot array mapping, and proximity ligation assay staining approaches establish that human AKAP79-anchored PKC selectively phosphorylates the Robo3.1 receptor subtype on serine 1330. These findings imply that anchored PKC locally modulates the phosphorylation status of Robo3.1 in brain regions governing learning and memory and reward.
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Affiliation(s)
- Bret K Samelson
- From the Howard Hughes Medical Institute, Department of Pharmacology, and
| | - Bryan B Gore
- the Departments of Pharmacology and Psychiatry, University of Washington, Seattle, Washington 98195-7290
| | - Jennifer L Whiting
- From the Howard Hughes Medical Institute, Department of Pharmacology, and
| | - Patrick J Nygren
- From the Howard Hughes Medical Institute, Department of Pharmacology, and
| | - Alicia M Purkey
- the Department of Pharmacology, University of Colorado, Aurora, Colorado 80045, and
| | | | - Lorene K Langeberg
- From the Howard Hughes Medical Institute, Department of Pharmacology, and
| | - Mark L Dell'Acqua
- the Department of Pharmacology, University of Colorado, Aurora, Colorado 80045, and
| | - Larry S Zweifel
- the Departments of Pharmacology and Psychiatry, University of Washington, Seattle, Washington 98195-7290
| | - John D Scott
- From the Howard Hughes Medical Institute, Department of Pharmacology, and
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19
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Sweeney MO, Collins A, Padrick SB, Goode BL. A novel role for WAVE1 in controlling actin network growth rate and architecture. Mol Biol Cell 2014; 26:495-505. [PMID: 25473116 PMCID: PMC4310740 DOI: 10.1091/mbc.e14-10-1477] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
A novel functional role for WAVE1 is found that is lacking in N-WASP and WAVE2. Through its unique WH2 domain, WAVE1 dramatically reduces the rate of actin filament elongation independently of its interactions with the Arp2/3 complex. These findings help explain how cells build actin networks with distinct geometries and growth rates. Branched actin filament networks in cells are assembled through the combined activities of Arp2/3 complex and different WASP/WAVE proteins. Here we used TIRF and electron microscopy to directly compare for the first time the assembly kinetics and architectures of actin filament networks produced by Arp2/3 complex and dimerized VCA regions of WAVE1, WAVE2, or N-WASP. WAVE1 produced strikingly different networks from WAVE2 or N-WASP, which comprised unexpectedly short filaments. Further analysis showed that the WAVE1-specific activity stemmed from an inhibitory effect on filament elongation both in the presence and absence of Arp2/3 complex, which was observed even at low stoichiometries of WAVE1 to actin monomers, precluding an effect from monomer sequestration. Using a series of VCA chimeras, we mapped the elongation inhibitory effects of WAVE1 to its WH2 (“V”) domain. Further, mutating a single conserved lysine residue potently disrupted WAVE1's inhibitory effects. Taken together, our results show that WAVE1 has unique activities independent of Arp2/3 complex that can govern both the growth rates and architectures of actin filament networks. Such activities may underlie previously observed differences between the cellular functions of WAVE1 and WAVE2.
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Affiliation(s)
- Meredith O Sweeney
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454
| | - Agnieszka Collins
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454
| | - Shae B Padrick
- Howard Hughes Medical Institute and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Bruce L Goode
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454;
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20
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Steering cell migration: lamellipodium dynamics and the regulation of directional persistence. Nat Rev Mol Cell Biol 2014; 15:577-90. [PMID: 25145849 DOI: 10.1038/nrm3861] [Citation(s) in RCA: 394] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Membrane protrusions at the leading edge of cells, known as lamellipodia, drive cell migration in many normal and pathological situations. Lamellipodial protrusion is powered by actin polymerization, which is mediated by the actin-related protein 2/3 (ARP2/3)-induced nucleation of branched actin networks and the elongation of actin filaments. Recently, advances have been made in our understanding of positive and negative ARP2/3 regulators (such as the SCAR/WAVE (SCAR/WASP family verprolin-homologous protein) complex and Arpin, respectively) and of proteins that control actin branch stability (such as glial maturation factor (GMF)) or actin filament elongation (such as ENA/VASP proteins) in lamellipodium dynamics and cell migration. This Review highlights how the balance between actin filament branching and elongation, and between the positive and negative feedback loops that regulate these activities, determines lamellipodial persistence. Importantly, directional persistence, which results from lamellipodial persistence, emerges as a critical factor in steering cell migration.
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21
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Burgers PP, van der Heyden MAG, Kok B, Heck AJR, Scholten A. A Systematic Evaluation of Protein Kinase A–A-Kinase Anchoring Protein Interaction Motifs. Biochemistry 2014; 54:11-21. [DOI: 10.1021/bi500721a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Pepijn P. Burgers
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- Netherlands Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
| | - Marcel A. G. van der Heyden
- Department
of Medical Physiology, Division of Heart and Lungs, University Medical Centre Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Bart Kok
- Department
of Medical Physiology, Division of Heart and Lungs, University Medical Centre Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- Netherlands Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
| | - Arjen Scholten
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- Netherlands Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
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22
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Looi CY, Sasahara Y, Watanabe Y, Satoh M, Hakozaki I, Uchiyama M, Wong WF, Du W, Uchiyama T, Kumaki S, Tsuchiya S, Kure S. The open conformation of WASP regulates its nuclear localization and gene transcription in myeloid cells. Int Immunol 2014; 26:341-52. [DOI: 10.1093/intimm/dxt072] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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23
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Abstract
The WAVE regulatory complex (WRC) is a 400-kDa heteropentameric protein assembly that plays a central role in controlling actin cytoskeletal dynamics in many cellular processes. The WRC acts by integrating diverse cellular cues and stimulating the actin nucleating activity of the Arp2/3 complex at membranes. Biochemical and biophysical studies of the underlying mechanisms of these processes require large amounts of purified WRC. Recent success in recombinant expression, reconstitution, purification, and crystallization of the WRC has greatly advanced our understanding of the inhibition, activation, and membrane recruitment mechanisms of this complex. But many important questions remain to be answered. Here, we summarize and update the methods developed in our laboratory, which allow reliable and flexible production of tens of milligrams of recombinant WRC of crystallographic quality, sufficient for many biochemical and structural studies.
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Affiliation(s)
- Baoyu Chen
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Shae B Padrick
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Lisa Henry
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Michael K Rosen
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA.
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24
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Sato K, Suzuki T, Yamaguchi Y, Kitade Y, Nagase T, Ueda H. PLEKHG2/FLJ00018, a Rho family-specific guanine nucleotide exchange factor, is tyrosine phosphorylated via the EphB2/cSrc signaling pathway. Cell Signal 2014; 26:691-6. [PMID: 24378532 DOI: 10.1016/j.cellsig.2013.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 12/18/2013] [Indexed: 10/25/2022]
Abstract
PLEKHG2/FLJ00018, a Rho family-specific guanine nucleotide exchange factor (RhoGEF), is activated by heterotrimeric GTP-binding protein (G protein) Gβγ subunits, and in turn activates the small G protein Rac and Cdc42, which have been shown to mediate signaling pathways leading to actin cytoskeletal reorganization. In the present study, we show that co-expression of the constitutively active mutant of cSrc, a non-receptor tyrosine kinase, and PLEKHG2 induced the tyrosine phosphorylation of PLEKHG2 in HEK293 cells. Through deletion and base substitution mutagenesis we have identified Tyr489 of PLEKHG2 as the site phosphorylated by cSrc. Furthermore, using a high-throughput src homology 2 (SH2) domain binding assay, the SH2 domain of ABL1 and the PI 3-kinse regulator subunit (PIK3R3) were identified as candidates for the binding partner of tyrosine-phosphorylated PLEKHG2. The interaction between PLEKHG2 and the full-length of PIK3R3, but not ABL1, occurs in a tyrosine-phosphorylation-dependent manner. Furthermore, PLEKHG2 is tyrosine phosphorylated at Tyr489 by ephrinB2 receptor signaling via cSrc. Investigation of the physiological function of tyrosine phosphorylation at Tyr489 in PLEKHG2 remains a subject for future studies.
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Affiliation(s)
- Katsuya Sato
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Yanagido, Gifu 501-1193, Japan
| | - Takahiro Suzuki
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan
| | | | - Yukio Kitade
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Yanagido, Gifu 501-1193, Japan; Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan
| | - Takahiro Nagase
- Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
| | - Hiroshi Ueda
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Yanagido, Gifu 501-1193, Japan; Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan.
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25
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Jessick VJ, Xie M, Pearson AN, Torrey DJ, Ashley MD, Thompson S, Meller R. Investigating the role of the actin regulating complex ARP2/3 in rapid ischemic tolerance induced neuro-protection. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2013; 5:216-227. [PMID: 24379906 PMCID: PMC3867699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 10/27/2013] [Indexed: 06/03/2023]
Abstract
Neuronal morphology is highly sensitive to ischemia, although some re-organization may promote neuroprotection. In this study we investigate the role of actin regulating proteins (ARP2, ARP3 and WAVE-1) and their role in rapid ischemic tolerance. Using an established in vitro model of rapid ischemic tolerance, we show that WAVE-1 protein levels are stabilized following brief tolerance inducing ischemia (preconditioning). The stabilization appears to be due to a reduction in the ubiquitination of WAVE-1. Levels of ARP2, ARP3 and N-WASP were not affected by ischemic preconditioning. Immunocytochemical studies show a relocalization of ARP2 and ARP3 proteins in neurons following preconditioning ischemia, as well as a re-organization of actin. Blocking the protein kinase CK2 using emodin blocks ischemic tolerance, and our data suggests CK2 binds to WAVE-1 in neurons. We observe an increase in binding of the ARP2 subunit with WAVE-1. The neuroprotection observed following preconditioning is inhibited when cells are transduced with an N-WASP CA domain that blocks the activation of ARP2/3. Together these data show that ischemia affects actin regulating enzymes, and that the ARP2/3 pathway plays a role in rapid ischemic tolerance induced neuroprotection.
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Affiliation(s)
- Veronica J Jessick
- Neuroscience Institute, Morehouse School of Medicine720 Westview Drive SW, Atlanta, GA, 30310, USA
| | - Mian Xie
- Neuroscience Institute, Morehouse School of Medicine720 Westview Drive SW, Atlanta, GA, 30310, USA
| | - Andrea N Pearson
- Neuroscience Institute, Morehouse School of Medicine720 Westview Drive SW, Atlanta, GA, 30310, USA
- Robert S. Dow Neurobiology Laboratories, Legacy ResearchPortland, Oregon, USA
| | - Dan J Torrey
- Neuroscience Institute, Morehouse School of Medicine720 Westview Drive SW, Atlanta, GA, 30310, USA
| | - Michelle D Ashley
- Neuroscience Institute, Morehouse School of Medicine720 Westview Drive SW, Atlanta, GA, 30310, USA
| | - Simon Thompson
- Neuroscience Institute, Morehouse School of Medicine720 Westview Drive SW, Atlanta, GA, 30310, USA
| | - Robert Meller
- Neuroscience Institute, Morehouse School of Medicine720 Westview Drive SW, Atlanta, GA, 30310, USA
- Robert S. Dow Neurobiology Laboratories, Legacy ResearchPortland, Oregon, USA
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26
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Rangamani P, Lipshtat A, Azeloglu EU, Calizo RC, Hu M, Ghassemi S, Hone J, Scarlata S, Neves SR, Iyengar R. Decoding information in cell shape. Cell 2013; 154:1356-69. [PMID: 24034255 DOI: 10.1016/j.cell.2013.08.026] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 05/30/2013] [Accepted: 08/14/2013] [Indexed: 12/28/2022]
Abstract
Shape is an indicator of cell health. But how is the information in shape decoded? We hypothesize that decoding occurs by modulation of signaling through changes in plasma membrane curvature. Using analytical approaches and numerical simulations, we studied how elongation of cell shape affects plasma membrane signaling. Mathematical analyses reveal transient accumulation of activated receptors at regions of higher curvature with increasing cell eccentricity. This distribution of activated receptors is periodic, following the Mathieu function, and it arises from local imbalance between reaction and diffusion of soluble ligands and receptors in the plane of the membrane. Numerical simulations show that transient microdomains of activated receptors amplify signals to downstream protein kinases. For growth factor receptor pathways, increasing cell eccentricity elevates the levels of activated cytoplasmic Src and nuclear MAPK1,2. These predictions were experimentally validated by changing cellular eccentricity, showing that shape is a locus of retrievable information storage in cells.
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Affiliation(s)
- Padmini Rangamani
- Department of Pharmacology and Systems Therapeutics and Systems Biology Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
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Zhou S, Tang L, Wang H, Dai J, Zhang J, Shen L, Ng SW, Berkowitz RS. Overexpression of c-Abl predicts unfavorable outcome in epithelial ovarian cancer. Gynecol Oncol 2013; 131:69-76. [PMID: 23820113 DOI: 10.1016/j.ygyno.2013.06.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 06/21/2013] [Accepted: 06/23/2013] [Indexed: 12/18/2022]
Abstract
OBJECTIVES Abelson tyrosine kinase (c-Abl) has been shown to promote solid tumor invasion and metastasis. However, little is known regarding whether c-Abl contributes to the development or progression of epithelial ovarian cancer (EOC). The aims of this study are to determine the expression of c-Abl and investigate a possible relationship between c-Abl and prognosis in EOC. METHODS c-Abl protein level was evaluated in 137 EOC specimens by immunohistochemical staining and 32 EOC specimens by Western blot analysis. Expression of c-Abl in ovarian cancer cell lines was measured by Western blot analysis and immunofluorescence. Survival analysis was performed to assess the correlation between c-Abl expression and survival. RESULTS Immunohistochemical staining and Western blot analysis revealed that c-Abl was overexpressed in EOC compared with samples from a non-invasive ovarian tumor and normal ovaries (P<0.05). Furthermore, expression of c-Abl was significantly associated with advanced FIGO stage, poor grade, serum Ca-125 and residual tumor size (P<0.05). By Western blot analysis, c-Abl expression was examined in four ovarian cancer cell lines. Meanwhile, immunofluorescence was performed to show c-Abl expression in SKOV3 and 3AO cell lines. Survival analysis demonstrated that patients with low c-Abl staining had a significantly better survival compared to patients with high c-Abl staining (P<0.05). In multivariate analysis, c-Abl overexpression, poor grade, advanced stage and suboptimal surgical debulking were independent prognostic factors of poor survival. CONCLUSIONS Our present study finds that c-Abl overexpression is associated with an unfavorable outcome. c-Abl may be a crucial predictor for EOC metastasis.
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Affiliation(s)
- Suiyang Zhou
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, People's Republic of China
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Matt U, Sharif O, Martins R, Furtner T, Langeberg L, Gawish R, Elbau I, Zivkovic A, Lakovits K, Oskolkova O, Doninger B, Vychytil A, Perkmann T, Schabbauer G, Binder CJ, Bochkov VN, Scott JD, Knapp S. WAVE1 mediates suppression of phagocytosis by phospholipid-derived DAMPs. J Clin Invest 2013; 123:3014-24. [PMID: 23934128 DOI: 10.1172/jci60681] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 05/02/2013] [Indexed: 01/20/2023] Open
Abstract
Clearance of invading pathogens is essential to preventing overwhelming inflammation and sepsis that are symptomatic of bacterial peritonitis. Macrophages participate in this innate immune response by engulfing and digesting pathogens, a process called phagocytosis. Oxidized phospholipids (OxPL) are danger-associated molecular patterns (DAMPs) generated in response to infection that can prevent the phagocytic clearance of bacteria. We investigated the mechanism underlying OxPL action in macrophages. Exposure to OxPL induced alterations in actin polymerization, resulting in spreading of peritoneal macrophages and diminished uptake of E. coli. Pharmacological and cell-based studies showed that an anchored pool of PKA mediates the effects of OxPL. Gene silencing approaches identified the A-kinase anchoring protein (AKAP) WAVE1 as an effector of OxPL action in vitro. Chimeric Wave1(-/-) mice survived significantly longer after infection with E. coli and OxPL treatment in vivo. Moreover, we found that endogenously generated OxPL in human peritoneal dialysis fluid from end-stage renal failure patients inhibited phagocytosis via WAVE1. Collectively, these data uncover an unanticipated role for WAVE1 as a critical modulator of the innate immune response to severe bacterial infections.
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Affiliation(s)
- Ulrich Matt
- Research Center for Molecular Medicine of Austrian Academy of Sciences, Vienna, Austria
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29
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Predicting protein-protein interactions in the post synaptic density. Mol Cell Neurosci 2013; 56:128-39. [PMID: 23628905 DOI: 10.1016/j.mcn.2013.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 04/09/2013] [Accepted: 04/19/2013] [Indexed: 12/27/2022] Open
Abstract
The post synaptic density (PSD) is a specialization of the cytoskeleton at the synaptic junction, composed of hundreds of different proteins. Characterizing the protein components of the PSD and their interactions can help elucidate the mechanism of long-term changes in synaptic plasticity, which underlie learning and memory. Unfortunately, our knowledge of the proteome and interactome of the PSD is still partial and noisy. In this study we describe a computational framework to improve the reconstruction of the PSD network. The approach is based on learning the characteristics of PSD protein interactions from a set of trusted interactions, expanding this set with data collected from large scale repositories, and then predicting novel interaction with proteins that are suspected to reside in the PSD. Using this method we obtained thirty predicted interactions, with more than half of which having supporting evidence in the literature. We discuss in details two of these new interactions, Lrrtm1 with PSD-95 and Src with Capg. The first may take part in a mechanism underlying glutamatergic dysfunction in schizophrenia. The second suggests an alternative mechanism to regulate dendritic spines maturation.
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30
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Sossey-Alaoui K. Surfing the big WAVE: Insights into the role of WAVE3 as a driving force in cancer progression and metastasis. Semin Cell Dev Biol 2013; 24:287-97. [PMID: 23116924 PMCID: PMC4207066 DOI: 10.1016/j.semcdb.2012.10.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/16/2012] [Accepted: 10/17/2012] [Indexed: 02/06/2023]
Abstract
WAVE3 belongs to the WASP/WAVE family of actin cytoskeleton remodeling proteins. These proteins are known to be involved in several biological functions ranging from controlling cell shape and movement, to being closely associated with pathological conditions such as cancer progression and metastasis. Last decade has seen an explosion in the literature reporting significant scientific advances on the molecular mechanisms whereby the WASP/WAVE proteins are regulated both in normal physiological as well as pathological conditions. The purpose of this review is to present the major findings pertaining to how WAVE3 has become a critical player in the regulation of signaling pathways involved in cancer progression and metastasis. The review will conclude with suggesting options for the potential use of WAVE3 as a therapeutic target to prevent the progression of cancer to the lethal stage that is the metastatic disease.
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Affiliation(s)
- Khalid Sossey-Alaoui
- Department of Molecular Cardiology, Cleveland Clinic Lerner Research Institute, 9500 Euclid Ave., NB-50, Cleveland, OH 44195, USA.
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31
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Mendoza MC. Phosphoregulation of the WAVE regulatory complex and signal integration. Semin Cell Dev Biol 2013; 24:272-9. [PMID: 23354023 DOI: 10.1016/j.semcdb.2013.01.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Accepted: 01/16/2013] [Indexed: 01/19/2023]
Abstract
The WAVE2 regulatory complex (WRC) induces actin polymerization by activating the actin nucleator Arp2/3. Polymerizing actin pushes against the cell membrane and induces dramatic edge protrusions. In order to properly control such changes in cell morphology and function, cells have evolved multiple methods to tightly regulate WRC and Arp2/3 activity in space and time. Of these mechanisms, phosphorylation plays a fundamental role in transmitting extracellular and intracellular signals to the WRC and the actin cytoskeleton. This review discusses the phosphorylation-based regulatory inputs into the WRC. Signaling pathways that respond to growth factors, chemokines, hormones, and extracellular matrix converge upon the WAVE and ABI components of the WRC. The Abl, Src, ERK, and PKA kinases promote complex activation through a WRC conformation change that permits interaction with the Arp2/3 complex and through WRC translocation to the cell edge. The neuron-specific CDK5 and constitutively active CK2 kinases inhibit WRC activation. These regulatory signals are integrated in space and time as they coalesce upon the WRC. The combination of WRC phosphorylation events and WRC activity is controlled by stimulus, cell type, and cell cycle-specific pathway activation and via pathway cross-inhibition and cross-activation.
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Affiliation(s)
- Michelle C Mendoza
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, United States.
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32
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Itoh T, Hasegawa J. Mechanistic insights into the regulation of circular dorsal ruffle formation. J Biochem 2012; 153:21-9. [PMID: 23175656 DOI: 10.1093/jb/mvs138] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Growth factor stimulations induce dynamic changes in the cytoskeleton beneath the plasma membrane. Among them is the formation of membrane ruffles organized in a circular array, called 'circular dorsal ruffles' (CDRs). Physiological functions of CDRs include downregulation of cell growth by desensitizing the signalling from growth factor receptors as well as rearrangement of adhesion sites at the onset of cell migration. For the formation of CDRs, not only the activators of actin polymerization, such as N-WASP and the Arp2/3-complex, but also membrane deforming proteins with BAR/F-BAR domains are necessary. Small GTPases are also involved in the formation of CDRs by controlling intracellular trafficking through endosomes. Moreover, recent analyses of another circular cytoskeletal structure, podosome rosettes, have revealed common molecular features shared with CDRs. Among them, the roles of PI3-kinase and phosphoinositide 5-phosphatase may hold the key to the induction of these circular structures.
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Affiliation(s)
- Toshiki Itoh
- Division of Membrane Biology, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe 650-0017, Japan.
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Modified SH2 domain to phototrap and identify phosphotyrosine proteins from subcellular sites within cells. Proc Natl Acad Sci U S A 2012; 109:E2929-38. [PMID: 23027962 DOI: 10.1073/pnas.1207358109] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Spatial regulation of tyrosine phosphorylation is important for many aspects of cell biology. However, phosphotyrosine accounts for less than 1% of all phosphorylated substrates, and it is typically a very transient event in vivo. These factors complicate the identification of key tyrosine kinase substrates, especially in the context of their extraordinary spatial organization. Here, we describe an approach to identify tyrosine kinase substrates based on their subcellular distribution from within cells. This method uses an unnatural amino acid-modified Src homology 2 (SH2) domain that is expressed within cells and can covalently trap phosphotyrosine proteins on exposure to light. This SH2 domain-based photoprobe was targeted to cellular structures, such as the actin cytoskeleton, mitochondria, and cellular membranes, to capture tyrosine kinase substrates unique to each cellular region. We demonstrate that RhoA, one of the proteins associated with actin, can be phosphorylated on two tyrosine residues within the switch regions, suggesting that phosphorylation of these residues might modulate RhoA signaling to the actin cytoskeleton. We conclude that expression of SH2 domains within cellular compartments that are capable of covalent phototrapping can reveal the spatial organization of tyrosine kinase substrates that are likely to be important for the regulation of subcellular structures.
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Abstract
Cells construct a number of plasma membrane structures to meet a range of physiological demands. Driven by juxtamembrane actin machinery, these actin-based membrane protrusions are essential for the operation and maintenance of cellular life. They are required for diverse cellular functions, such as directed cell motility, cell spreading, adhesion, and substrate/matrix degradation. Circular dorsal ruffles (CDRs) are one class of such structures characterized as F-actin-rich membrane projections on the apical cell surface. CDRs commence their formation minutes after stimulation as flat, open, and immature ruffles and progressively develop into fully enclosed circular ruffles. These "rings" then mature and contract centrifugally before subsiding. Serving a critical function in receptor internalization and cell migration, CDRs are thus highly dynamic but transient formations. Here, we review the current state of knowledge concerning the regulation of circular dorsal ruffles. We focus specifically on the biochemical pathways leading to CDR formation in order to better define the roles and functions of these enigmatic structures.
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Functional mechanisms and roles of adaptor proteins in abl-regulated cytoskeletal actin dynamics. JOURNAL OF SIGNAL TRANSDUCTION 2012; 2012:414913. [PMID: 22675626 PMCID: PMC3362954 DOI: 10.1155/2012/414913] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 03/16/2012] [Indexed: 01/20/2023]
Abstract
Abl is a nonreceptor tyrosine kinase and plays an essential role in the modeling and remodeling of F-actin by transducing extracellular signals. Abl and its paralog, Arg, are unique among the tyrosine kinase family in that they contain an unusual extended C-terminal half consisting of multiple functional domains. This structural characteristic may underlie the role of Abl as a mediator of upstream signals to downstream signaling machineries involved in actin dynamics. Indeed, a group of SH3-containing accessory proteins, or adaptor proteins, have been identified that bind to a proline-rich domain of the C-terminal portion of Abl and modulate its kinase activity, substrate recognition, and intracellular localization. Moreover, the existence of signaling cascade and biological outcomes unique to each adaptor protein has been demonstrated. In this paper, we summarize functional roles and mechanisms of adaptor proteins in Abl-regulated actin dynamics, mainly focusing on a family of adaptor proteins, Abi. The mechanism of Abl's activation and downstream signaling mediated by Abi is described in comparison with those by another adaptor protein, Crk.
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36
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Okada H, Uezu A, Soderblom EJ, Moseley MA, Gertler FB, Soderling SH. Peptide array X-linking (PAX): a new peptide-protein identification approach. PLoS One 2012; 7:e37035. [PMID: 22606326 PMCID: PMC3351392 DOI: 10.1371/journal.pone.0037035] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 04/12/2012] [Indexed: 12/19/2022] Open
Abstract
Many protein interaction domains bind short peptides based on canonical sequence consensus motifs. Here we report the development of a peptide array-based proteomics tool to identify proteins directly interacting with ligand peptides from cell lysates. Array-formatted bait peptides containing an amino acid-derived cross-linker are photo-induced to crosslink with interacting proteins from lysates of interest. Indirect associations are removed by high stringency washes under denaturing conditions. Covalently trapped proteins are subsequently identified by LC-MS/MS and screened by cluster analysis and domain scanning. We apply this methodology to peptides with different proline-containing consensus sequences and show successful identifications from brain lysates of known and novel proteins containing polyproline motif-binding domains such as EH, EVH1, SH3, WW domains. These results suggest the capacity of arrayed peptide ligands to capture and subsequently identify proteins by mass spectrometry is relatively broad and robust. Additionally, the approach is rapid and applicable to cell or tissue fractions from any source, making the approach a flexible tool for initial protein-protein interaction discovery.
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Affiliation(s)
- Hirokazu Okada
- Department of Cell Biology, Duke University Medical School, Durham, North Carolina, United States of America
| | - Akiyoshi Uezu
- Department of Cell Biology, Duke University Medical School, Durham, North Carolina, United States of America
| | - Erik J. Soderblom
- Institute for Genome Science & Policy Proteomics Core Facility, Duke University Medical School, Durham, North Carolina, United States of America
| | - M. Arthur Moseley
- Institute for Genome Science & Policy Proteomics Core Facility, Duke University Medical School, Durham, North Carolina, United States of America
| | - Frank B. Gertler
- Koch Institute for Integrative Cancer Research at MIT, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Scott H. Soderling
- Department of Cell Biology, Duke University Medical School, Durham, North Carolina, United States of America
- * E-mail:
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Okada H, Uezu A, Mason FM, Soderblom EJ, Moseley MA, Soderling SH. SH3 domain-based phototrapping in living cells reveals Rho family GAP signaling complexes. Sci Signal 2011; 4:rs13. [PMID: 22126966 DOI: 10.1126/scisignal.2002189] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Rho family GAPs [guanosine triphosphatase (GTPase) activating proteins] negatively regulate Rho family GTPase activity and therefore modulate signaling events that control cytoskeletal dynamics. The spatial distribution of these GAPs and their specificity toward individual GTPases are controlled by their interactions with various proteins within signaling complexes. These interactions are likely mediated through the Src homology 3 (SH3) domain, which is abundant in the Rho family GAP proteome and exhibits a micromolar binding affinity, enabling the Rho family GAPs to participate in transient interactions with multiple binding partners. To capture these elusive GAP signaling complexes in situ, we developed a domain-based proteomics approach, starting with in vivo phototrapping of SH3 domain-binding proteins and the mass spectrometry identification of associated proteins for nine representative Rho family GAPs. After the selection of candidate binding proteins by cluster analysis, we performed peptide array-based high-throughput in vitro binding assays to confirm the direct interactions and map the SH3 domain-binding sequences. We thereby identified 54 SH3-mediated binding interactions (including 51 previously unidentified ones) for nine Rho family GAPs. We constructed Rho family GAP interactomes that provided insight into the functions of these GAPs. We further characterized one of the predicted functions for the Rac-specific GAP WRP and identified a role for WRP in mediating clustering of the postsynaptic scaffolding protein gephyrin and the GABA(A) (γ-aminobutyric acid type A) receptor at inhibitory synapses.
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Affiliation(s)
- Hirokazu Okada
- Department of Cell Biology, Duke University Medical School, Durham, NC 27710, USA
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Darie CC, Deinhardt K, Zhang G, Cardasis HS, Chao MV, Neubert TA. Identifying transient protein-protein interactions in EphB2 signaling by blue native PAGE and mass spectrometry. Proteomics 2011; 11:4514-28. [PMID: 21932443 DOI: 10.1002/pmic.201000819] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 08/23/2011] [Accepted: 08/31/2011] [Indexed: 11/11/2022]
Abstract
Receptor tyrosine kinases (RTKs) are proteins that upon ligand stimulation undergo dimerization and autophosphorylation. Eph receptors (EphRs) are RTKs that are found in different cell types, from both tissues that are developing and from mature tissues, and play important roles in the development of the central nervous system and peripheral nervous system. EphRs also play roles in synapse formation, neural crest formation, angiogenesis and in remodeling the vascular system. Interaction of EphRs with their ephrin ligands lead to activation of signal transduction pathways and formation of many transient protein-protein interactions that ultimately leads to cytoskeletal remodeling. However, the sequence of events at the molecular level is not well understood. We used blue native PAGE and MS to analyze the transient protein-protein interactions that resulted from the stimulation of EphB2 receptors by their ephrinB1-Fc ligands. We analyzed the phosphotyrosine-containing protein complexes immunoprecipitated from the cell lysates of both unstimulated (-) and ephrinB1-Fc-stimulated (+) NG108 cells. Our experiments allowed us to identify many signaling proteins, either known to be part of EphB2 signaling or new for this pathway, which are involved in transient protein-protein interactions upon ephrinB1-Fc stimulation. These data led us to investigate the roles of proteins such as FAK, WAVEs and Nischarin in EphB2 signaling.
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Affiliation(s)
- Costel C Darie
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York, NY, USA.
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Dyachok J, Zhu L, Liao F, He J, Huq E, Blancaflor EB. SCAR mediates light-induced root elongation in Arabidopsis through photoreceptors and proteasomes. THE PLANT CELL 2011; 23:3610-26. [PMID: 21972261 PMCID: PMC3229138 DOI: 10.1105/tpc.111.088823] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 09/09/2011] [Accepted: 09/17/2011] [Indexed: 05/18/2023]
Abstract
The ARP2/3 complex, a highly conserved nucleator of F-actin, and its activator, the SCAR complex, are essential for growth in plants and animals. In this article, we present a pathway through which roots of Arabidopsis thaliana directly perceive light to promote their elongation. The ARP2/3-SCAR complex and the maintenance of longitudinally aligned F-actin arrays are crucial components of this pathway. The involvement of the ARP2/3-SCAR complex in light-regulated root growth is supported by our finding that mutants of the SCAR complex subunit BRK1/HSPC300, or other individual subunits of the ARP2/3-SCAR complex, showed a dramatic inhibition of root elongation in the light, which mirrored reduced growth of wild-type roots in the dark. SCAR1 degradation in dark-grown wild-type roots by constitutive photomorphogenic 1 (COP1) E3 ligase and 26S proteasome accompanied the loss of longitudinal F-actin and reduced root growth. Light perceived by the root photoreceptors, cryptochrome and phytochrome, suppressed COP1-mediated SCAR1 degradation. Taken together, our data provide a biochemical explanation for light-induced promotion of root elongation by the ARP2/3-SCAR complex.
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Affiliation(s)
- Julia Dyachok
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Ling Zhu
- Section of Molecular Cell and Developmental Biology and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712
| | - Fuqi Liao
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Ji He
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Enamul Huq
- Section of Molecular Cell and Developmental Biology and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712
| | - Elison B. Blancaflor
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
- Address correspondence to
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Okunishi K, Sisson TH, Huang SK, Hogaboam CM, Simon RH, Peters-Golden M. Plasmin overcomes resistance to prostaglandin E2 in fibrotic lung fibroblasts by reorganizing protein kinase A signaling. J Biol Chem 2011; 286:32231-43. [PMID: 21795691 DOI: 10.1074/jbc.m111.235606] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Collagen deposition by fibroblasts contributes to scarring in fibrotic diseases. Activation of protein kinase A (PKA) by cAMP represents a pivotal brake on fibroblast activation, and the lipid mediator prostaglandin E(2) (PGE(2)) exerts its well known anti-fibrotic actions through cAMP signaling. However, fibrotic fibroblasts from the lungs of patients with idiopathic pulmonary fibrosis, or of mice with bleomycin-induced fibrosis, are resistant to the normal collagen-inhibiting action of PGE(2). In this study, we demonstrate that plasminogen activation to plasmin restores PGE(2) sensitivity in fibrotic lung fibroblasts from human and mouse. This involves amplified PKA signaling resulting from the promotion of new interactions between AKAP9 and PKA regulatory subunit II in the perinuclear region as well as from the inhibition of protein phosphatase 2A. This is the first report to show that an extracellular mediator can dramatically reorganize and amplify the intracellular PKA-A-kinase anchoring protein signaling network and suggests a new strategy to control collagen deposition by fibrotic fibroblasts.
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Affiliation(s)
- Katsuhide Okunishi
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, Michigan 48109, USA
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Cross-talk between calcium and protein kinase A in the regulation of cell migration. Curr Opin Cell Biol 2011; 23:554-61. [PMID: 21665456 DOI: 10.1016/j.ceb.2011.05.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 05/16/2011] [Accepted: 05/17/2011] [Indexed: 12/31/2022]
Abstract
Calcium (Ca(2+)) and the cAMP-dependent protein kinase (PKA) are pleiotropic cellular regulators and both exert powerful, diverse effects on cytoskeletal dynamics, cell adhesion, and cell migration. Localization, by A-kinase-anchoring proteins (AKAPs), of PKA activity to the protrusive leading edge, integrins, and other regulators of cytoskeletal dynamics has emerged as an important facet of its role in cell migration. Additional recent work has firmly established the importance of Ca(2+) influx through mechanosensitive transient receptor potential (TRP) channels and through store-operated Ca(2+) entry (SOCE) in cell migration. Finally, there is considerable evidence showing that these mechanisms of Ca(2+) influx and PKA regulation intersect--and often interact--and thus may work in concert to translate complex extracellular cues into the intracellular biochemical anisotropy required for directional cell migration.
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Hou T, Li Y, Wang W. Prediction of peptides binding to the PKA RIIalpha subunit using a hierarchical strategy. ACTA ACUST UNITED AC 2011; 27:1814-21. [PMID: 21586518 DOI: 10.1093/bioinformatics/btr294] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
MOTIVATION Favorable interaction between the regulatory subunit of the cAMP-dependent protein kinase (PKA) and a peptide in A-kinase anchoring proteins (AKAPs) is critical for translocating PKA to the subcellular sites where the enzyme phosphorylates its substrates. It is very hard to identify AKAPs peptides binding to PKA due to the high sequence diversity of AKAPs. RESULTS We propose a hierarchical and efficient approach, which combines molecular dynamics (MD) simulations, free energy calculations, virtual mutagenesis (VM) and bioinformatics analyses, to predict peptides binding to the PKA RIIα regulatory subunit in the human proteome systematically. Our approach successfully retrieved 15 out of 18 documented RIIα-binding peptides. Literature curation supported that many newly predicted peptides might be true AKAPs. Here, we present the first systematic search for AKAP peptides in the human proteome, which is useful to further experimental identification of AKAPs and functional analysis of their biological roles.
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Affiliation(s)
- Tingjun Hou
- Institute of Functional Nano & Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, PR China.
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Logue JS, Whiting JL, Tunquist B, Langeberg LK, Scott JD. Anchored protein kinase A recruitment of active Rac GTPase. J Biol Chem 2011; 286:22113-21. [PMID: 21460214 PMCID: PMC3121355 DOI: 10.1074/jbc.m111.232660] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Protein kinase A-anchoring proteins (AKAPs) influence fundamental cellular processes by directing the cAMP-dependent protein kinase (PKA) toward its intended substrates. In this report we describe the identification and characterization of a ternary complex of AKAP220, the PKA holoenzyme, and the IQ domain GTPase-activating protein 2 isoform (IQGAP2) that is enriched at cortical regions of the cell. Formation of an IQGAP2-AKAP220 core complex initiates a subsequent phase of protein recruitment that includes the small GTPase Rac. Biochemical and molecular biology approaches reveal that PKA phosphorylation of Thr-716 on IQGAP2 enhances association with the active form of the Rac GTPase. Cell-based experiments indicate that overexpression of an IQGAP2 phosphomimetic mutant (IQGAP2 T716D) enhances the formation of actin-rich membrane ruffles at the periphery of HEK 293 cells. In contrast, expression of a nonphosphorylatable IQGAP2 T716A mutant or gene silencing of AKAP220 suppresses formation of membrane ruffles. These findings imply that IQGAP2 and AKAP220 act synergistically to sustain PKA-mediated recruitment of effectors such as Rac GTPases that impact the actin cytoskeleton.
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Affiliation(s)
- Jeremy S Logue
- Howard Hughes Medical Institute, University of Washington School of Medicine, Seattle, Washington 98195, USA
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Sossey-Alaoui K, Downs-Kelly E, Das M, Izem L, Tubbs R, Plow EF. WAVE3, an actin remodeling protein, is regulated by the metastasis suppressor microRNA, miR-31, during the invasion-metastasis cascade. Int J Cancer 2011; 129:1331-43. [PMID: 21105030 DOI: 10.1002/ijc.25793] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 10/26/2010] [Indexed: 12/21/2022]
Abstract
WAVE3, an actin cytoskeleton remodeling protein, is highly expressed in advanced stages of breast cancer and influences tumor cell invasion. Loss of miR-31 has been associated with cancer progression and metastasis. Here, we show that the activity of WAVE3 to promote cancer cell invasion is regulated by miR-31. An inverse correlation was demonstrated between expression levels of WAVE3 and miR-31 in invasive versus noninvasive breast cancer cell lines. miR-31 directly targeted the 3'-UTR of the WAVE3 mRNA and inhibited its expression in the invasive cancer cells, i.e., miR-31-mediated down-regulation of WAVE3 resulted in a significant reduction in the invasive phenotype of cancer cells. This relationship was specific to the loss of WAVE3 expression because re-expression of a miR-31-resistant form of WAVE3 reversed miR-31-mediated inhibition of cancer cell invasion. Furthermore, expression of miR-31 correlates inversely with breast cancer progression in humans, where an increase in expression of miR-31 target genes was observed as the tumors progressed to more aggressive forms. In conclusion, a novel mechanism for the regulation of WAVE3 expression in cancer cells has been identified, which controls the invasive properties of cancer cells. The study also identifies a critical role for WAVE3, downstream of miR-31, in the invasion-metastasis cascade.
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Affiliation(s)
- Khalid Sossey-Alaoui
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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Wessler S, Backert S. Abl family of tyrosine kinases and microbial pathogenesis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 286:271-300. [PMID: 21199784 DOI: 10.1016/b978-0-12-385859-7.00006-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Abl nonreceptor tyrosine kinases are activated by multiple stimuli and regulate cytoskeletal reorganization, cell proliferation, survival, and stress responses. Several downstream pathways have direct impact on physiological processes, including development and maintenance of the nervous and immune systems and epithelial morphogenesis. Recent studies also indicated that numerous viral and bacterial pathogens highjack Abl signaling for different purposes. Abl kinases are activated to reorganize the host actin cytoskeleton and promote the direct tyrosine phosphorylation of viral surface proteins and injected bacterial type-III and type-IV effector molecules. However, Abl kinases also play other roles in infectious processes of bacteria, viruses, and prions. These activities have crucial impact on microbial invasion and release from host cells, actin-based motility, pedestal formation, as well as cell-cell dissociation involved in epithelial barrier disruption and other responses. Thus, Abl kinases exhibit important functions in pathological signaling during microbial infections. Here, we discuss the different signaling pathways activated by pathogens and highlight possible therapeutic intervention strategies.
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Affiliation(s)
- Silja Wessler
- Department of Molecular Biology, Division of Microbiology, Paris-Lodron University of Salzburg, Billrothstrasse, Salzburg, Austria
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Mason FM, Heimsath EG, Higgs HN, Soderling SH. Bi-modal regulation of a formin by srGAP2. J Biol Chem 2010; 286:6577-86. [PMID: 21148482 DOI: 10.1074/jbc.m110.190397] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The maintenance of rapid and efficient actin dynamics in vivo requires coordination of filament assembly and disassembly. This regulation requires temporal and spatial integration of signaling pathways by protein complexes. However, it remains unclear how these complexes form and then regulate the actin cytoskeleton. Here, we identify a srGAP2 and formin-like 1 (FMNL1, also known as FRL1 or FRLα) complex whose assembly is regulated by Rac signaling. Our data suggest srGAP2 regulates FMNL1 in two ways; 1) Rac-mediated activation of FMNL1 leads to the recruitment of srGAP2, which contains a Rac-specific GAP domain; 2) the SH3 domain of srGAP2 binds the formin homology 1 domain of FMNL1 to inhibit FMNL1-mediated actin severing. Thus, srGAP2 can efficiently terminate the upstream activating Rac signal while also opposing an important functional output of FMNL1, namely actin severing. We also show that FMNL1 and srGAP2 localize to the actin-rich phagocytic cup of macrophage-derived cells, suggesting the complex may regulate this Rac- and actin-driven process in vivo. We propose that after Rac-dependent activation of FMNL1, srGAP2 mediates a potent mechanism to limit the duration of Rac action and inhibit formin activity during rapid actin dynamics.
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Affiliation(s)
- Frank M Mason
- Department of Cell Biology, Duke University Medical School, Durham, North Carolina 27710, USA
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Yamashita H, Ueda K, Kioka N. WAVE2 forms a complex with PKA and is involved in PKA enhancement of membrane protrusions. J Biol Chem 2010; 286:3907-14. [PMID: 21119216 DOI: 10.1074/jbc.m110.145409] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PKA contributes to many physiological processes, including glucose homeostasis and cell migration. The substrate specificity of PKA is low compared with other kinases; thus, complex formation with A-kinase-anchoring proteins is important for the localization of PKA in specific subcellular regions and the phosphorylation of specific substrates. Here, we show that PKA forms a complex with WAVE2 (Wiskott-Aldrich syndrome protein family verprolin-homologous protein 2) in MDA-MB-231 breast cancer cells and mouse brain extracts. Two separate regions of WAVE2 are involved in WAVE2-PKA complex formation. This complex localizes to the leading edge of MDA-MB-231 cells. PKA activation results in enlargement of the membrane protrusion. WAVE2 depletion impairs PKA localization at membrane protrusions and the enlargement of membrane protrusion induced by PKA activation. Together, these results suggest that WAVE2 works as an A-kinase-anchoring protein that recruits PKA at membrane protrusions and plays a role in the enlargement of membrane protrusions induced by PKA activation.
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Affiliation(s)
- Hiroshi Yamashita
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan
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Abstract
ABL-family proteins comprise one of the best conserved branches of the tyrosine kinases. Each ABL protein contains an SH3-SH2-TK (Src homology 3-Src homology 2-tyrosine kinase) domain cassette, which confers autoregulated kinase activity and is common among nonreceptor tyrosine kinases. This cassette is coupled to an actin-binding and -bundling domain, which makes ABL proteins capable of connecting phosphoregulation with actin-filament reorganization. Two vertebrate paralogs, ABL1 and ABL2, have evolved to perform specialized functions. ABL1 includes nuclear localization signals and a DNA binding domain through which it mediates DNA damage-repair functions, whereas ABL2 has additional binding capacity for actin and for microtubules to enhance its cytoskeletal remodeling functions. Several types of posttranslational modifications control ABL catalytic activity, subcellular localization, and stability, with consequences for both cytoplasmic and nuclear ABL functions. Binding partners provide additional regulation of ABL catalytic activity, substrate specificity, and downstream signaling. Information on ABL regulatory mechanisms is being mined to provide new therapeutic strategies against hematopoietic malignancies caused by BCR-ABL1 and related leukemogenic proteins.
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Affiliation(s)
- John Colicelli
- Department of Biological Chemistry, Molecular Biology Institute and Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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Hermo L, Pelletier RM, Cyr DG, Smith CE. Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 3: developmental changes in spermatid flagellum and cytoplasmic droplet and interaction of sperm with the zona pellucida and egg plasma membrane. Microsc Res Tech 2010; 73:320-63. [PMID: 19941287 DOI: 10.1002/jemt.20784] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Spermiogenesis constitutes the steps involved in the metamorphosis of spermatids into spermatozoa. It involves modification of several organelles in addition to the formation of several structures including the flagellum and cytoplasmic droplet. The flagellum is composed of a neck region and middle, principal, and end pieces. The axoneme composed of nine outer microtubular doublets circularly arranged to form a cylinder around a central pair of microtubules is present throughout the flagellum. The middle and principal pieces each contain specific components such as the mitochondrial sheath and fibrous sheath, respectively, while outer dense fibers are common to both. A plethora of proteins are constituents of each of these structures, with each playing key roles in functions related to the fertility of spermatozoa. At the end of spermiogenesis, a portion of spermatid cytoplasm remains associated with the released spermatozoa, referred to as the cytoplasmic droplet. The latter has as its main feature Golgi saccules, which appear to modify the plasma membrane of spermatozoa as they move down the epididymal duct and hence may be partly involved in male gamete maturation. The end product of spermatogenesis is highly streamlined and motile spermatozoa having a condensed nucleus equipped with an acrosome. Spermatozoa move through the female reproductive tract and eventually penetrate the zona pellucida and bind to the egg plasma membrane. Many proteins have been implicated in the process of fertilization as well as a plethora of proteins involved in the development of spermatids and sperm, and these are high lighted in this review.
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Affiliation(s)
- Louis Hermo
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada H3A 2B2.
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Mechanisms of protein kinase A anchoring. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 283:235-330. [PMID: 20801421 DOI: 10.1016/s1937-6448(10)83005-9] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The second messenger cyclic adenosine monophosphate (cAMP), which is produced by adenylyl cyclases following stimulation of G-protein-coupled receptors, exerts its effect mainly through the cAMP-dependent serine/threonine protein kinase A (PKA). Due to the ubiquitous nature of the cAMP/PKA system, PKA signaling pathways underlie strict spatial and temporal control to achieve specificity. A-kinase anchoring proteins (AKAPs) bind to the regulatory subunit dimer of the tetrameric PKA holoenzyme and thereby target PKA to defined cellular compartments in the vicinity of its substrates. AKAPs promote the termination of cAMP signals by recruiting phosphodiesterases and protein phosphatases, and the integration of signaling pathways by binding additional signaling proteins. AKAPs are a heterogeneous family of proteins that only display similarity within their PKA-binding domains, amphipathic helixes docking into a hydrophobic groove formed by the PKA regulatory subunit dimer. This review summarizes the current state of information on compartmentalized cAMP/PKA signaling with a major focus on structural aspects, evolution, diversity, and (patho)physiological functions of AKAPs and intends to outline newly emerging directions of the field, such as the elucidation of AKAP mutations and alterations of AKAP expression in human diseases, and the validation of AKAP-dependent protein-protein interactions as new drug targets. In addition, alternative PKA anchoring mechanisms employed by noncanonical AKAPs and PKA catalytic subunit-interacting proteins are illustrated.
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